Merge remote-tracking branch 'origin/master' into codex/pr199-merge-master-20260717

# Conflicts:
#	docs/rfc/INDEX.md
This commit is contained in:
Tianyi Cui
2026-07-17 21:13:43 +08:00
1348 changed files with 117238 additions and 23882 deletions

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@@ -8,25 +8,28 @@ Generated by `pnpm run gen-rfc-index` from the RFC tree — never edit by hand;
| Title | First proposed |
|---|---|
| [Agent Client Protocol (ACP) support — drive the coding agent from external editors](proposed/feature/2026-06-14-acp-agent-client-protocol.md) | 2026-06-14 |
| [Multiplex concurrent ACP sessions over one connection](proposed/feature/2026-06-14-acp-multi-session.md) | 2026-06-14 |
| [Optional Code Mode — model writes TypeScript against an SDK of all tools](proposed/feature/2026-06-15-optional-code-mode.md) | 2026-06-15 |
| [Pre-tool input rewrite — a consistent design](proposed/feature/2026-06-30-pre-tool-input-rewrite.md) | 2026-06-30 |
| [Recallable compaction — index checkpoints, a state checkpoint, and in-session history recall](proposed/feature/2026-07-06-recallable-compaction.md) | 2026-07-06 |
| [Claude Code and Codex subagent backends (out-of-process delegation to external coding agents)](proposed/feature/2026-07-07-claude-code-and-codex-subagent-backends.md) | 2026-07-07 |
| [Interactive side sessions and merge-back](proposed/feature/2026-07-08-interactive-side-sessions.md) | 2026-07-08 |
| [SQLite FTS5 session search](proposed/feature/2026-07-10-sqlite-session-query-provider.md) | 2026-07-10 |
| [Stream workflow progress through tool calls](proposed/feature/2026-07-13-stream-workflow-progress-through-tool-calls.md) | 2026-07-13 |
| [Developer-owned SDK projects](proposed/feature/2026-07-14-sdk-developer-projects.md) | 2026-07-14 |
### Simplification
| Title | First proposed |
|---|---|
| [Unify the agent id and the session id](proposed/simplification/2026-06-20-unify-agent-and-session-id.md) | 2026-06-20 |
| [Prune dead core-spine surface — `SurfaceManager.invalidate()`, the loop-internal exports, `ToolExecutionResult.callId`](proposed/simplification/2026-07-04-prune-dead-core-spine-surface.md) | 2026-07-04 |
| [Prune dead public and result surface](proposed/simplification/2026-07-04-prune-dead-core-spine-surface.md) | 2026-07-04 |
| [Simplify session-log representation](proposed/simplification/2026-07-12-simplify-session-log-representation.md) | 2026-07-12 |
### Architecture
| Title | First proposed |
|---|---|
| [Runtime schemas for the event vocabulary (Zod vs the merge-extensible-map pattern)](proposed/architecture/2026-06-16-typed-event-schemas.md) | 2026-06-16 |
| [Extract a generic long-running tool runtime](proposed/architecture/2026-06-20-generic-long-running-tool-runtime.md) | 2026-06-20 |
| [SDK project editing architecture](proposed/architecture/2026-07-15-sdk-project-editing-architecture.md) | 2026-07-15 |
### Process
@@ -36,6 +39,7 @@ Generated by `pnpm run gen-rfc-index` from the RFC tree — never edit by hand;
| [Architectural conformance — dependency rules and the adapter kit](proposed/process/2026-06-11-architectural-conformance.md) | 2026-06-11 |
| [Supply chain checks and vendor drift verification](proposed/process/2026-06-11-supply-chain-and-vendor-drift.md) | 2026-06-11 |
| [Discover package inventories instead of maintaining static lists](proposed/process/2026-06-20-discover-package-inventory.md) | 2026-06-20 |
| [Periodic human-review maintenance for dsh-code-review](proposed/process/2026-07-13-human-review-skill-maintenance.md) | 2026-07-13 |
### Testing
@@ -50,17 +54,39 @@ Generated by `pnpm run gen-rfc-index` from the RFC tree — never edit by hand;
| Title | First proposed |
|---|---|
| [Agent Client Protocol (ACP) support — drive the coding agent from external editors](implemented/feature/2026-06-14-acp-agent-client-protocol.md) | 2026-06-14 |
| [Multiplex concurrent ACP sessions over one connection](implemented/feature/2026-06-14-acp-multi-session.md) | 2026-06-14 |
| [Code Mode — the model writes TypeScript against the tool registry](implemented/feature/2026-06-15-code-mode.md) | 2026-06-15 |
| [Filesystem tool schemas — model-facing read/write/edit shapes](implemented/feature/2026-06-17-filesystem-tool-schemas.md) | 2026-06-17 |
| [Rich ACP bash rendering — the terminal card via the `_meta` convention](implemented/feature/2026-06-18-acp-terminal-and-tool-rendering.md) | 2026-06-18 |
| [Compaction as a capability seam (abstract contract + basic backend)](implemented/feature/2026-06-18-compaction-capability-seam.md) | 2026-06-18 |
| [Subagent capability seam](implemented/feature/2026-06-21-subagent-capability-seam.md) | 2026-06-21 |
| [ACP subagent backend (out-of-process delegation)](implemented/feature/2026-06-22-acp-subagent-backend.md) | 2026-06-22 |
| [Workspace context instruction files](implemented/feature/2026-06-24-workspace-context.md) | 2026-06-24 |
| [Ask-user question capability](implemented/feature/2026-06-25-ask-user-question.md) | 2026-06-25 |
| [The `todo_write` tool — model task list as event-sourced session state](implemented/feature/2026-06-29-todo-write-tool.md) | 2026-06-29 |
| [dsh-hooks-claude + dsh-hooks-codex — the Claude Code / Codex hook bridges](implemented/feature/2026-06-30-hook-bridges.md) | 2026-06-30 |
| [dsh-hook-protocol — the shared Claude Code / Codex hook wire-protocol core](implemented/feature/2026-06-30-hook-protocol-lib.md) | 2026-06-30 |
| [Interception seams — the typed-Decision surface a hook programs against](implemented/feature/2026-06-30-interception-seams.md) | 2026-06-30 |
| [SessionStore fork API](implemented/feature/2026-06-30-session-store-fork-api.md) | 2026-06-30 |
| [Subagent lifecycle enrichment — lastAssistantMessage (observe-only)](implemented/feature/2026-06-30-subagent-observe-enrich.md) | 2026-06-30 |
| [Dynamic workflows — a script-driven multi-agent orchestration seam](implemented/feature/2026-07-05-dynamic-workflows.md) | 2026-07-05 |
| [Skill system — progressive disclosure instructions for agents](implemented/feature/2026-07-05-skill-system.md) | 2026-07-05 |
| [The approval seam — one-shot permission decisions over a waterfall of answerers](implemented/feature/2026-07-06-approval-seam.md) | 2026-07-06 |
| [Explicit model-facing tool order](implemented/feature/2026-07-06-explicit-tool-order.md) | 2026-07-06 |
| [The subprocess sandbox — confinement seam, native runners, escalation, and per-session modes](implemented/feature/2026-07-06-sandbox.md) | 2026-07-06 |
| [MCP client plugin — connect to external MCP servers and bridge their tools](implemented/feature/2026-07-07-mcp-client-plugin.md) | 2026-07-07 |
| [The session prefix — request-only messages in front of the derived history](implemented/feature/2026-07-07-session-prefix.md) | 2026-07-07 |
| [Background subagent tasks](implemented/feature/2026-07-08-background-subagent-tasks.md) | 2026-07-08 |
| [Repeat-tool-call guard plugin](implemented/feature/2026-07-08-repeat-tool-guard.md) | 2026-07-08 |
| [The self-referential cordis toolset](implemented/feature/2026-07-08-self-referential-cordis-toolset.md) | 2026-07-08 |
| [Bash-backed grep and glob discovery tools](implemented/feature/2026-07-09-bash-backed-grep-glob-discovery.md) | 2026-07-09 |
| [Expose agent session identity and JSONL location to tools and hooks](implemented/feature/2026-07-10-agent-session-identity-and-log-location.md) | 2026-07-10 |
| [Exact session query service](implemented/feature/2026-07-10-session-query-service.md) | 2026-07-10 |
| [Configure subagent persona, tool visibility, and depth](implemented/feature/2026-07-12-subagent-persona-tool-filter-and-depth.md) | 2026-07-12 |
| [Session query relationship tracing](implemented/feature/2026-07-13-session-query-tracing.md) | 2026-07-13 |
| [Optional time-context plugin](implemented/feature/2026-07-14-time-context-plugin.md) | 2026-07-14 |
| [Durable per-step time context](implemented/feature/2026-07-16-durable-per-step-time-context.md) | 2026-07-16 |
### Simplification
@@ -85,6 +111,8 @@ Generated by `pnpm run gen-rfc-index` from the RFC tree — never edit by hand;
| [Share the app bins' boot glue instead of maintaining twin copies](implemented/simplification/2026-07-04-share-app-bin-boot-glue.md) | 2026-07-04 |
| [Tighten the hook-protocol contract — dialect, discarded fields, double defaults, and lib-owned `hook/result` semantics](implemented/simplification/2026-07-04-tighten-hook-protocol-contract.md) | 2026-07-04 |
| [Trim unreachable ACP bridge surface — the branding knobs and the kind-sniffing fallback](implemented/simplification/2026-07-04-trim-acp-bridge-unreachable-surface.md) | 2026-07-04 |
| [Drop unconsumed skill provider events](implemented/simplification/2026-07-12-drop-unconsumed-skill-provider-events.md) | 2026-07-12 |
| [Prune unused web seam fields](implemented/simplification/2026-07-12-prune-unused-web-seam-fields.md) | 2026-07-12 |
### Architecture
@@ -92,7 +120,7 @@ Generated by `pnpm run gen-rfc-index` from the RFC tree — never edit by hand;
|---|---|
| [Provider-neutral content-block vocabulary owned by dsh-llm](implemented/architecture/2026-06-11-content-block-vocabulary.md) | 2026-06-11 |
| [Custom typed tool-schema DSL instead of schemastery](implemented/architecture/2026-06-11-custom-schema-dsl.md) | 2026-06-11 |
| [Dev-mode invariants over compile-time deep-readonly](implemented/architecture/2026-06-11-dev-invariants-over-deep-readonly.md) | 2026-06-11 |
| [Source-owned session immutability and dev-mode invariants](implemented/architecture/2026-06-11-dev-invariants-over-deep-readonly.md) | 2026-06-11 |
| [Event-sourced sessions with derived message history](implemented/architecture/2026-06-11-event-sourced-sessions.md) | 2026-06-11 |
| [Microkernel — extension via Cordis event taxonomy, one concrete loop](implemented/architecture/2026-06-11-microkernel-event-taxonomy.md) | 2026-06-11 |
| [Runtime arg validation at the model boundary](implemented/architecture/2026-06-11-runtime-arg-validation.md) | 2026-06-11 |
@@ -108,6 +136,7 @@ Generated by `pnpm run gen-rfc-index` from the RFC tree — never edit by hand;
| [Shared persistence write coordinator](implemented/architecture/2026-06-18-shared-persistence-write-coordinator.md) | 2026-06-18 |
| [Branded IDs everywhere they belong](implemented/architecture/2026-06-20-branded-ids.md) | 2026-06-20 |
| [Extract example apps into packages](implemented/architecture/2026-06-20-extract-example-app-packages.md) | 2026-06-20 |
| [The background task runtime (`ctx.tasks`) and generic task control tools](implemented/architecture/2026-06-20-generic-long-running-tool-runtime.md) | 2026-06-20 |
| [Reorganize packages into a modular hierarchy](implemented/architecture/2026-06-20-package-hierarchy.md) | 2026-06-20 |
| [Mandatory `User-Agent` attribution for provider requests](implemented/architecture/2026-06-21-mandatory-app-attribution-headers.md) | 2026-06-21 |
| [Web capability seam - stable tools over multiple providers](implemented/architecture/2026-06-24-web-capability-seam.md) | 2026-06-24 |
@@ -121,6 +150,13 @@ Generated by `pnpm run gen-rfc-index` from the RFC tree — never edit by hand;
| [Prompt variables and tool-guidance ownership](implemented/architecture/2026-07-05-prompt-variables-and-tool-guidance-ownership.md) | 2026-07-05 |
| [Every LLM request is reconstructable from the session log](implemented/architecture/2026-07-05-reconstructable-requests.md) | 2026-07-05 |
| [Subagent provider-lifecycle events — `subagent/provider-added` / `subagent/provider-removed`](implemented/architecture/2026-07-05-subagent-provider-lifecycle-events.md) | 2026-07-05 |
| [A shared timeout/deadline primitive, with hard-kill left to each capability](implemented/architecture/2026-07-06-timeout-deadline-library.md) | 2026-07-06 |
| [Tool result retention library](implemented/architecture/2026-07-06-tool-result-retention-library.md) | 2026-07-06 |
| [Tool-call timeout policy as a plugin](implemented/architecture/2026-07-07-tool-call-timeout-policy.md) | 2026-07-07 |
| [The agent is a registration scope](implemented/architecture/2026-07-08-agent-scope-contexts.md) | 2026-07-08 |
| [Tool output spill policy](implemented/architecture/2026-07-08-tool-output-spill-files.md) | 2026-07-08 |
| [Single-file executable SDK runtime distribution (single-exe)](implemented/architecture/2026-07-10-single-file-executable-sdk-runtime-distribution.md) | 2026-07-10 |
| [Agent-scope runtime design and correctness](implemented/architecture/2026-07-12-agent-scope-runtime-design.md) | 2026-07-12 |
### Process
@@ -146,8 +182,12 @@ Generated by `pnpm run gen-rfc-index` from the RFC tree — never edit by hand;
| [One gated in-file format for RFCs](implemented/process/2026-07-05-uniform-rfc-format.md) | 2026-07-05 |
| [Export-surface JSDoc gate](implemented/process/2026-07-06-export-surface-jsdoc-gate.md) | 2026-07-06 |
| [Generated plugin config catalog](implemented/process/2026-07-06-generated-config-catalog.md) | 2026-07-06 |
| [Raise the Node LTS engine floor to 22.19](implemented/process/2026-07-06-node-engine-floor.md) | 2026-07-06 |
| [Parallel GitHub CI gates](implemented/process/2026-07-06-parallel-github-ci-gates.md) | 2026-07-06 |
| [Parallel pre-push gates](implemented/process/2026-07-06-parallel-pre-push-gates.md) | 2026-07-06 |
| [A gated Known-Limitations section in every package README](implemented/process/2026-07-10-readme-known-limitations-gate.md) | 2026-07-10 |
| [Package Model Experience contract](implemented/process/2026-07-12-package-model-experience-contract.md) | 2026-07-12 |
| [TypeScript Program-backed semantic gates](implemented/process/2026-07-14-typescript-program-backed-semantic-gates.md) | 2026-07-14 |
### Testing
@@ -163,6 +203,7 @@ Generated by `pnpm run gen-rfc-index` from the RFC tree — never edit by hand;
| [Hook snapshot matrix — end-to-end goldens for both bridges](implemented/testing/2026-07-04-hook-snapshot-matrix.md) | 2026-07-04 |
| [Single-source the acp-agent replay config](implemented/testing/2026-07-04-single-source-acp-replay-config.md) | 2026-07-04 |
| [Pin request-header content in one snapshot scenario](implemented/testing/2026-07-06-pin-request-header-content-in-one-scenario.md) | 2026-07-06 |
| [Extract the ACP snapshot suite into a support package](implemented/testing/2026-07-08-shared-acp-snapshot-package.md) | 2026-07-08 |
## Rejected
@@ -182,6 +223,8 @@ Generated by `pnpm run gen-rfc-index` from the RFC tree — never edit by hand;
| [Return the ACP bridge to one live session per connection](rejected/simplification/2026-06-20-single-session-acp-bridge.md) | 2026-06-20 |
| [Truncate interrupted final turns on load](rejected/simplification/2026-06-20-truncate-interrupted-turns.md) | 2026-06-20 |
| [Prune the unimplemented subagent seam vocabulary](rejected/simplification/2026-07-04-prune-unimplemented-subagent-vocabulary.md) | 2026-07-04 |
| [Collapse workflows to the exercised foreground core](rejected/simplification/2026-07-12-collapse-workflow-to-foreground-core.md) | 2026-07-12 |
| [Prune unused skill registry surface](rejected/simplification/2026-07-12-prune-unused-skill-registry-surface.md) | 2026-07-12 |
### Architecture

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@@ -16,7 +16,7 @@ The date in the filename is when the topic was **first proposed** (per git histo
## Classification
Each RFC is filed under exactly one **class** — the kind of decision it records. The class is encoded in the path (the folder *is* the label, so a file's location declares its class) and the set is **closed**: `scripts/rfc-index.ts` owns the canonical set, `scripts/verify-rfc-classification.ts` rejects any folder outside it, and [INDEX.md](INDEX.md) is **generated** from the tree in full (`pnpm run gen-rfc-index` rewrites it from each RFC's path, H1 title, and filename date; the gate fails when it is stale, and rejects an index-shaped row in this file). Adding a new class means amending that `const` and this section, not just dropping a new folder. See [the classification RFC](implemented/process/2026-06-20-rfc-classification.md) for why the taxonomy is path-encoded and gated, and [the index-generation RFC](implemented/process/2026-07-04-generate-rfc-index-tables.md) for why the index is generated while this prose stays curated.
Each RFC belongs to one path-encoded class from the closed set in `scripts/rfc-index.ts`; the classification gate rejects other folders. [INDEX.md](INDEX.md) is generated from paths, titles, and filename dates, and its freshness is gated. Adding a class requires updating the canonical set and this section. See the [classification](implemented/process/2026-06-20-rfc-classification.md) and [index-generation](implemented/process/2026-07-04-generate-rfc-index-tables.md) RFCs.
| Class | What it covers |
|---|---|

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@@ -1,15 +1,11 @@
# AGENTS.md — Implemented RFCs
These are RFCs whose decision has **shipped**. The repo-wide and docs-wide rules still apply ([root AGENTS.md](../../../AGENTS.md) § "Type safety and documentation", [docs/AGENTS.md](../../AGENTS.md)), and the in-file skeleton — including the proposal→implemented rewrite a lifecycle move owes — is [README.md § The file format](../README.md#the-file-format), gated by `verify-rfc-format`; this file adds one rule specific to this folder.
These RFCs describe shipped decisions. Follow the [root instructions](../../../AGENTS.md), [documentation standard](../../AGENTS.md), and [RFC format](../README.md#the-file-format); `verify-rfc-format` gates the lifecycle-specific structure.
## Keep an implemented RFC current with what actually shipped
An RFC in `implemented/` describes a decision that is now **live code**. Keep its description of the shipped reality accurate: when the implementation later moves a file, renames a package or symbol, changes a config key/default/error code, or relocates a plugin, update the RFC in the **same change** that touches the code — exactly as you would a package README. A stale implemented RFC (pointing at a path that no longer exists, naming a package that was renamed, describing a structure that was refactored) is worse than no RFC: a future reader trusts it and is misled.
Update it **in place** to state the current truth. Do **not** leave the outdated text in and bolt on a "superseded / now actually…" note — that makes the document a changelog of its own drift and forces the reader to reconstruct the present from a pile of corrections. Write what is true now.
Keep paths, symbols, defaults, and mechanisms current in the same change that alters them. Rewrite stale facts in place; do not append change history.
### This is not a license to rewrite the *decision*
Keeping the shipped-state description current is about **facts** (paths, names, structure, defaults) — not about silently flipping the **decision and its rationale** into a different one. The "new RFC" escape hatch is for **macro** changes — a genuine reversal of *what was decided* or its rationale — NOT for renames, moves, or structural relocations. A rename is always a fact to fix **in place**: leaving a package/symbol/path at its old name (even with a "was renamed to…" aside) only confuses a reader who greps the current tree for a name that no longer exists. So: the package was renamed, a symbol changed, a plugin moved, the decision is now realized through a different mechanism → edit this RFC to state the current names and structure. Only a reversal of *what was decided* a new RFC and cross-link, per [rfc/README.md](../README.md) ("An RFC is never edited into a different decision").
When in doubt, ask whether a reader following this RFC to the code would land on something real. If not, it needs updating.
Update factual realization in place. A reversal of the decision or its rationale requires a new RFC and cross-link; see [rfc/README.md](../README.md).

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@@ -10,7 +10,7 @@ The harness needs one internal language for messages that the loop, session log,
Own the vocabulary: messages are arrays of typed content blocks (`text`, `reasoning`, `tool-call`, `tool-result`), with the union derived from the merge-extensible `ContentBlockMap` so plugins add block types via declaration merging. The same merge-extensible-map pattern types every "stringly" field (`MessageSource`, `FinishReason`, `TurnTrigger`, `TurnEndReason`). Streaming is a raw chunk protocol; `BlockAssembler` is the single shared assembly implementation. Adapters translate to provider wire formats — mapping cost lives in adapters, where it belongs.
In-session context injection (`context/message`, `steering/message`) renders as tagged user-role envelopes (the system-reminder pattern) rather than a new role, so adapters carry zero burden. Live-adapter review has since validated the tagged-envelope rendering against current DeepSeek behavior; a future provider-specific mismatch should be handled in that adapter rather than by adding a new role to the canonical content vocabulary.
In-session context injection (`context/message`, `steering/message`) renders as tagged user-role envelopes (the system-reminder pattern) rather than a new role, so adapters carry zero burden. Live-adapter validation confirms this rendering for current DeepSeek behavior; a future provider-specific mismatch belongs in that adapter rather than a new canonical role.
## Alternatives considered
@@ -19,6 +19,8 @@ In-session context injection (`context/message`, `steering/message`) renders as
## Consequences
- Reasoning has a home without provider contortions. Multimodal content deliberately has NO core block type: the core set is limited to blocks every shipping path honors, and a multimodal feature adds its block type through the merge-extensible map in the same coordinated change that maps it in the adapters, surfaces it in the UI bridges, and prices it in compaction — see [the drop-image RFC](../simplification/2026-07-04-drop-image-content-block.md). Block cache hints likewise have no core field: DeepSeek prompt caching is automatic, so no shipping adapter can transmit a hint; a caching feature adds a `cache` field together with the adapter that honors it — see [the producer-less-variants RFC](../simplification/2026-07-04-prune-producerless-vocabulary-variants.md). Assistant-prefix continuation (prefill) likewise has no request field: DeepSeek's chat-prefix completion is a Beta feature on a base URL neither shipping adapter targets, so a prefill feature adds `GenerateOptions.prefill` together with the adapter that honors it — see [the inert-request-knobs RFC](../simplification/2026-07-04-drop-inert-request-knobs.md).
- Reasoning has a core home without provider-specific shapes.
- Multimodal blocks return only with coordinated adapter, UI, and compaction support; see [the drop-image RFC](../simplification/2026-07-04-drop-image-content-block.md).
- Cache hints and assistant prefill remain absent until a shipping adapter can honor them; see the [producer-less variants](../simplification/2026-07-04-prune-producerless-vocabulary-variants.md) and [inert request knobs](../simplification/2026-07-04-drop-inert-request-knobs.md) RFCs.
- Every adapter pays a translation cost; the first real adapters have since validated the streaming protocol, and new adapters should continue proving their provider-specific mapping in adapter-local tests.
- IDs that cross package boundaries are branded (`CallId`, `SessionId`, `AgentId`) — nominal typing at zero runtime cost.

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@@ -4,7 +4,7 @@ Status: implemented
## Problem
Tool parameters must reach the model as standard JSON Schema (the wire format), and tool authors deserve typed `execute(args)` without casts. The repo already vendors schemastery (used for plugin Config), so reusing it was the obvious candidate. The user also explicitly preferred per-property `required: true` booleans over JSON Schema's separate `required` array.
Tool parameters must reach the model as standard JSON Schema while giving tool authors typed `execute(args)` without casts. Schemastery already serves plugin config, but the tool-author API needs per-property `required: true` booleans rather than JSON Schema's separate `required` array.
## Decision
@@ -18,4 +18,4 @@ A small custom DSL in dsh-tools: `SchemaSpec` (per-property specs with `required
- First-party tool authors get zero-cast typed args; the type gymnastics cost stays inside the core package (sanctioned by the AGENTS.md type-safety policy).
- The DSL is deliberately small (string/number/boolean/object/array, enum, default, nested properties/items). Gaps vs full JSON Schema (unions, formats, constraints) are accepted until real tools demand them.
- The InferArgs mapping is regression-tested at the type level (expectTypeOf) after an early optionality bug shipped and was caught by review.
- The `InferArgs` mapping is regression-tested at the type level after an early optionality bug.

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@@ -1,29 +1,58 @@
# RFC: Dev-mode invariants over compile-time deep-readonly
# RFC: Source-owned session immutability and dev-mode invariants
Status: implemented
## Problem
The session log is append-only by contract, but the types don't enforce it: `session.events` returns `readonly SessionEvent[]` whose *elements* are mutable, and `deriveMessages()` handed the logged `content` arrays/blocks out by reference. The loop then passes those derived messages into the `agent/request` waterfall and on to adapters, where mutating the request is sanctioned — so a request middleware could reach back and rewrite history, silently breaking replay equivalence and the derived-history guarantee. Separately, the event taxonomy (turn/step nesting, seq monotonicity, tool-call/result pairing, legal status transitions) was asserted only where individual tests happened to look.
The session log needs two different protections: immutable ownership of each stored fact, and checks for relationships among facts across time and service seams. Conflating them in an optional development plugin would leave production history vulnerable; trying to express both through TypeScript readonly types would not create a runtime boundary or describe relational rules.
Two ways to defend the log: make immutability part of the type (`DeepReadonly<SessionEvent>` on the way out), or catch corruption at runtime in dev. The runtime-validation proposal took the runtime route; [the deep-readonly proposal](../../rejected/architecture/2026-06-11-immutable-public-surfaces.md) took the type route.
The session log is the durable source of truth for replay, request reconstruction, persistence, and user-visible history. Code outside the session package must be able to inspect that history without retaining a reference that can rewrite it later, and inputs accepted from callers must not remain connected to caller-owned mutable objects.
Immutability of individual values is only half of the contract. A log can contain perfectly immutable records whose sequence, turn/step nesting, tool-call pairing, scoped delivery, or reconstructed model request is wrong. Those rules relate multiple records or services and cannot be established by freezing one object.
TypeScript readonly types are not a sufficient runtime boundary. They disappear when the program runs, a cast can bypass them, and a recursive `DeepReadonly<T>` would spread through every log and message consumer even though some downstream request-processing APIs intentionally work with mutable values.
## Decision
Reject the pervasive `DeepReadonly<T>` type flip. Instead:
Responsibility is split between an always-on storage boundary and optional development assertions.
1. **Always-on:** `deriveMessages()` deep-clones the content it emits (one `structuredClone` per derived message). In-flight mutation of a request can no longer reach the log — this is the real fix, and it costs nothing meaningful next to a model call.
2. **Dev-mode:** a new `dsh-invariants` plugin (pure listeners, off in production, on in tests and demos) asserts the event contract and `Object.freeze`s logged event data so any *other* code that mutates a logged event throws instead of corrupting silently. Seeded sessions are frozen and checked on `session/created` (the constructor copies the seed without emitting `session/event`).
### Session owns immutable history
The invariants encode the *real* contract, not an idealized one: a `tool/call` may have no `tool/result` (a thrown tool-execution pipeline step ends the turn), and both `idle→disposed` and `running→disposed` are legal.
`Session` accepts an event only after one recursive pass has materialized a lossless JSON snapshot. That pass rejects unsupported values and produces the exact detached record that enters the log, so validation and storage cannot observe different values from a stateful getter or retain caller-owned nested references.
The accepted event and all of its descendants are deep-frozen before publication. `append()` returns that owned frozen event, `session/event` observers receive the same record, and `session.events` returns a frozen array snapshot. A previously returned array does not grow after a later append. Seed records pass through the same validation, snapshot, and freeze boundary before construction succeeds.
This guarantee belongs in `Session`, not in an optional listener, because every composition relies on trustworthy history. A production deployment, a focused test, or a custom embedding receives the same storage semantics whether or not development support plugins are registered.
### Derived requests remain detached
`deriveMessages()` projects logged surface events into detached, deep-frozen `Message` objects and returns a fresh array snapshot. Request assembly can therefore combine derived history with other inputs without exposing a path back into the log. The cache reuses safe immutable projections rather than recloning the complete history for each model call.
### The invariants plugin checks relationships
`dsh-invariants` is a pure-listener development plugin. It does not freeze records and has no configuration; disposal removes only its assertions. It checks rules that require trace state or observation of another seam, including monotonic sequence numbers, turn and step nesting, tool-call/result pairing, legal agent-status transitions, subject-correct scoped dispatch, and equality between a loop-built request and the request reconstructed from its session-log prefix.
When the plugin attaches to an existing or seeded session, it replays the immutable log to rebuild trace state. This makes hot reload safe in the middle of a turn without giving the plugin ownership of session storage.
## Alternatives considered
**The pervasive `DeepReadonly<T>` type flip** ([the rejected proposal](../../rejected/architecture/2026-06-11-immutable-public-surfaces.md)) — compile-time only (a plugin casts straight through it), high type-noise across every log/message consumer and adapter, and it would force readonly types through code where mutation is the sanctioned API. The clone draws the mutable/immutable boundary exactly at "logged vs in-flight" without any of that noise.
### Pervasive deep-readonly types
[The rejected immutable-public-surfaces proposal](../../rejected/architecture/2026-06-11-immutable-public-surfaces.md) would apply a recursive readonly type across public log and message surfaces. That provides editor feedback but not a runtime guarantee: TypeScript types are erased and plugin code can cast through them. It also pushes readonly types into consumers where mutation is intentional. Runtime ownership at the `Session` boundary protects every caller without that type propagation.
### Development-only freezing
Freezing history only when an invariants plugin is installed would make the core guarantee composition-dependent. Code could pass development tests and still corrupt history in production or in a focused composition that omits the plugin. Storage immutability is therefore always on, while the more expensive relational checks remain opt-in development support.
### Clone only when deriving messages
Detaching `deriveMessages()` would protect the most common request path but leave other readers of `session.events`, append return values, and session-event observers able to mutate durable history. The log must protect its own boundary; derived projections are an additional isolation boundary, not a substitute.
## Consequences
- History corruption is caught loudly in tests and demos, at zero production cost and zero type noise. The trade-off is that the guarantee is dynamic (a dev-mode tripwire) rather than static.
- The invariants plugin doubles as executable documentation of the event taxonomy — the assertions are the contract.
- `Session.events` keeps its `readonly SessionEvent[]` type; no consumer churn.
- This folds in [the deep-readonly proposal](../../rejected/architecture/2026-06-11-immutable-public-surfaces.md) — there is no separate deep-readonly record; this records the decision to *not* pursue that approach. `InvariantError` is a plain `Error` with a `code` for now; a later taxonomy change can promote it.
- Every accepted live or seeded session event is detached from caller-owned inputs and deeply immutable before any observer can receive it.
- `session.events` exposes stable immutable snapshots instead of the private growing array.
- Request-side mutation cannot reach stored history through derived messages.
- Development builds can enable relational assertions without changing storage behavior, and disposing or omitting the plugin does not weaken log immutability.
- `dsh-invariants` has no `Config` surface because it has no behavior to tune.
- The runtime boundary carries a recursive snapshot-and-freeze cost once per accepted event; later readers and cached projections reuse the owned immutable records.

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@@ -12,7 +12,7 @@ A `Session` is an append-only log of typed `SessionEvent`s — the single source
Appends are synchronous (the hot path never blocks on I/O); `session/event` is a sync notification; persistence plugins buffer write-behind and drain at the awaited `session/flush` checkpoint fired at every turn end.
Ordering contract: the loop appends to the session *before* emitting the corresponding Cordis event, and the `agent/step-result` waterfall runs before the `assistant/message` append so the log records what tool dispatch actually used (post-review fix; regression-tested).
Ordering contract: the loop appends to the session *before* emitting the corresponding Cordis event, and the `agent/step-result` waterfall runs before the `assistant/message` append so the log records the message tool dispatch actually used. Regression tests pin that ordering.
## Alternatives considered

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@@ -10,9 +10,10 @@ The product principle is "everything is a plugin": hooks, /goal, /loop, dynamic
Pure Cordis event taxonomy. The loop's extension seams are typed events with deliberate dispatch modes:
- **waterfall** (around-middleware) where plugins mutate or veto: `agent/prompt-submit`, `agent/request`, `agent/step-result`, `agent/turn-continuation`, `tools/pre-execute`, `tools/post-execute`, `llm/stream`, `system-prompt/assemble`.
- **emit** (sync fire-and-forget) for notifications: turn/step boundaries, stream chunks, lifecycle, errors.
- **parallel** (awaited) for the one durability checkpoint: `session/flush`.
- **waterfall** (around-middleware) where plugins transform, veto, or wrap: `agent/prompt-submit`, `agent/request`, `agent/step-result`, `agent/turn-continuation`, `tools/pre-execute`, `tools/execute`, `tools/post-execute`, `llm/stream`, `system-prompt/assemble`.
- **serial** (awaited in listener order; a bail value stops later listeners) for ordered checkpoints: every `agent/pre-step` listener runs when all abstain, while the first stop returned from `agent/turn-stop` makes the terminal decision final.
- **parallel** (awaited fan-out) where every listener must get an independent chance: the `session/flush` durability checkpoint.
- **emit** (synchronous fire-and-forget) for notifications: turn/step boundaries, stream chunks, lifecycle, errors, and the contained immutable `tools/result` observation.
The event vocabulary lives in interface packages (dsh-agent declares the agent/* events); `@deepseek-ai/dsh-agent-loop` is the only concrete loop plugin and is itself swappable — nothing outside it may depend on it.

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@@ -6,8 +6,6 @@ Status: implemented
Failures crossed seams as bare strings. A tool error flattened to a text block — name, code, and stack lost — so a future sandbox/retry plugin couldn't tell ENOENT from EACCES, and the model got less actionable feedback than it could. A non-Error throw degraded further: the loop wrapped it in `new Error(String(x))`, dropping any code. And `LlmError` was the only typed error in the system, with no shared base, so there was nothing for a consumer to `instanceof` against generically.
This is the last of the runtime-validation / error-taxonomy pieces and the one the user was most skeptical of, so it was deliberately built **last and in isolation**: the earlier PRs (arg validation, dev invariants) threw plain `Error`s with a `code` field, decoupled from any shared base, so this change is a pure upgrade and is independently revertible without unpicking them.
## Decision
A single `HarnessError extends Error` base in `dsh-llm` (the leaf package every other imports — no new dependency edge): a stable `code` distinct from `message`, `cause` chaining via `ErrorOptions`, and `name` defaulting to the subclass. `isHarnessError` narrows at seams.
@@ -21,6 +19,6 @@ A single `HarnessError extends Error` base in `dsh-llm` (the leaf package every
- Errors are machine-routable end-to-end: a plugin can branch on `error.code` rather than substring-matching a message.
- One base class is imported widely, but it lives in the package everyone already depends on, so the cost is a single import, not a new edge.
- `deriveMessages` does not surface `error` into model history — the model still sees the text block; the structured field is for code and replay.
- Reverting this PR returns the earlier errors to plain `Error`+`code` form; nothing else in the stack depends on the shared base.
- Argument validation and dev invariants retain their existing codes and behavior; the shared base adds cross-seam routing metadata without changing model-facing text.
<!-- rfc-format: alternatives-not-recorded (pre-format RFC) -->

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@@ -12,9 +12,9 @@ This is distinct from "who provides vs. needs a capability at runtime", which Co
A swappable capability is **three packages**:
1. **Interface** — an abstract service + the vocabulary types, owning the `ctx.<key>` and depending only on cordis (e.g. `dsh-bash`: `BashExecutor`, `BashRunResult`, `BashTask`).
1. **Interface** — an abstract service + the vocabulary types, owning the `ctx.<key>` and depending only on its vocabulary dependencies (e.g. `dsh-bash`: `BashExecutor`, `BashRunResult`, `BashProcess`).
2. **Implementation** — a concrete subclass loaded as a plugin (e.g. `dsh-bash-local`: subprocesses, process-group kills, spill-file truncation). Sandboxed/remote backends are sibling packages implementing the same interface.
3. **Consumer** — what the model and plugins see (e.g. `dsh-tool-bash`: the `bash`/`bash_output`/`bash_kill` tool schemas). Consumers `inject` the interface key and never import implementation types.
3. **Consumer** — what the model and plugins see (e.g. `dsh-tool-bash`: the `bash` schema, with background handles registered into the generic task runtime). Consumers `inject` the interface key and never import implementation types.
Implementation and consumer then evolve independently: a sandboxed executor replaces `dsh-bash-local` without touching a tool schema.

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@@ -22,4 +22,4 @@ The rule they enforce: **anything the StreamChunk vocabulary cannot express for
## Consequences
Double the adapter maintenance and double the key-gated e2e surface (both adapters cover V4 Flash and Pro across representative thinking/effort modes). Bought: a continuously-verified neutrality guarantee for the most leak-prone abstraction in the codebase, and a worked second example for adapter authors. The two share the core Config shape (`apiKey`/`baseURL`/`models`) so a deployment swaps mostly one line, but the reasoning knob differs — `dsh-llm-deepseek` takes `thinking`/`reasoningEffort`, `dsh-llm-pi-ai` takes a single `reasoning` level — so a swap translates that field. If the maintenance cost ever outweighs the verification value (e.g. once conformance tests from [architectural conformance](../../proposed/process/2026-06-11-architectural-conformance.md) cover the contract mechanically), retiring the twin to a single adapter + the conformance kit would be a new RFC superseding this one.
The twin doubles adapter and key-gated e2e maintenance—both cover V4 Flash and Pro across representative reasoning modes—in exchange for continuous seam-neutrality validation and a second implementation example. Both use `apiKey`, `baseURL`, and `models`; the hand-rolled adapter exposes `thinking`/`reasoningEffort`, while pi-ai exposes one `reasoning` level. A future conformance suite could justify retiring one adapter through a superseding RFC.

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@@ -2,11 +2,9 @@
Status: implemented
> Merges the original proposal and the decision record for one topic. The proposal's full method-surface and write-path detail lives in git history; this records the decision and the durable, contested choices.
## Problem
Sessions lived only in memory. The example `session-jsonl.ts` plugin (duplicated byte-for-byte in both examples) was write-only telemetry: it buffered `session/event` and appended JSON lines, with no read/replay path, no crash-safety (no fsync, no atomic write, a fire-and-forget dispose drain), no listing, and no format versioning. Nothing could rehydrate a past session from disk into a live agent, so durable resume ("continue yesterday's task"), durable forking, and the ACP `session/load` method ([ACP support](../../proposed/feature/2026-06-14-acp-agent-client-protocol.md)) were all impossible.
Sessions lived only in memory. The example `session-jsonl.ts` plugin (duplicated byte-for-byte in both examples) was write-only telemetry: it buffered `session/event` and appended JSON lines, with no read/replay path, no crash-safety (no fsync, no atomic write, a fire-and-forget dispose drain), no listing, and no format versioning. Nothing could rehydrate a past session from disk into a live agent, so durable resume ("continue yesterday's task"), durable forking, and the ACP `session/load` method ([ACP support](../../implemented/feature/2026-06-14-acp-agent-client-protocol.md)) were all impossible.
The [event-sourced model](2026-06-11-event-sourced-sessions.md) makes the append-only log the single source of truth and derives LLM history from it. Persistence had to stay faithful to that: persist the existing `SessionEvent` directly, with no parallel "persisted message" type that the log is converted to and from. The backend also had to be swappable — a file store now, a database store later — behind one interface.
@@ -20,10 +18,10 @@ Persistence is an abstract **capability seam** ([capability seams](2026-06-13-ca
Key choices recorded here because they are durable, contested, and surprising:
- **The canonical durable log persists every `SessionEvent` verbatim, including `assistant/chunk`.** `deriveMessages()` skips chunks, and a chunk-filtered rollout (Codex's `policy.rs`) is tempting — but `seq = log.length` and the load-validation `events[i].seq === i` require a *contiguous* log; filtering chunks out would leave holes and break both the contract and resume. A chunk-filtered projection is possible later as a derived view with its own renumbering, but it is NOT the canonical log.
- **Append-only; a crashed turn is closed, never truncated.** Committed events — those at or below a flushed `turn/end` are never rewritten. The loop only flushes at `turn/end`, so a crash can leave a durable log whose final turn never closed: real, fully-written events sit after the last `turn/end`. **A single turn can be huge in a long-horizon task** (many steps, large tool output spanning a long autonomous run), so discarding the interrupted turn would silently destroy a large amount of real work — truncating a turn is wrong. Instead, on reload `load` PRESERVES those events and CLOSES the orphaned turn by durably appending the minimal synthetic boundary events: an error `tool/result` for every `tool-call` the crash left unanswered, then a `step/end` if a step was still open, then a `turn/end` carrying the merge-extensible `{ kind: 'interrupted' }` reason (a marker that records the turn was cut short by a crash, not completed by the model — no loop ever emits it). The synthetic tool results matter for resume correctness: the loop logs the `assistant/message` (carrying the `tool-call` blocks) BEFORE running the tools, so a crash mid-tool leaves calls without results; `deriveMessages()` would then replay a dangling assistant tool-call, which every provider rejects as an invalid transcript on the next request. Answering each orphaned call with an error result keeps the rehydrated history valid. `load` returns the balanced log, so a resumed session is immediately usable. The ONLY thing discarded is a never-fully-written **torn tail fragment** — a final record whose bytes (JSONL) or row were never completely flushed; that fragment is not a valid event and is dropped before the synthetic closers are written. A parse error or `seq` gap in the COMMITTED region (at or before the last real `turn/end`) is genuine corruption and makes the session unloadable.
- **Append-only; a crashed turn is closed, never truncated.** Events through a flushed `turn/end` are never rewritten, and the loop flushes only at turn end. Because one interrupted turn may contain substantial valid work, `load` preserves its contiguous, parseable events and appends error results for unanswered tool calls, a missing `step/end`, and `turn/end` with `{ kind: 'interrupted' }`. The synthetic results keep resumed provider transcripts valid. Only an incomplete final record is discarded; a parse error or sequence gap at or before the last real `turn/end` is corruption and makes the session unloadable.
- **File backend canonical, DB backend a proven drop-in.** `SessionEvent` maps 1:1 onto a row `(session_id, seq, type, time, data)``append` is INSERT (in a transaction asserting the contiguous-seq contract), `load` is SELECT … ORDER BY seq. `dsh-session-persistence-sqlite` is exactly this: a `SessionPersistence` subclass with no interface change (opencode runs this exact shape on SQLite/WAL), and it passes the same `runPersistenceContract` suite as the JSONL backend — so the contract holds both backends to identical semantics (lazy materialization, interrupted-turn close on load, contiguous-seq), expressed once over file bytes and once over rows.
- **Metadata is out-of-log.** Format version, cwd, and lineage are storage concerns, not replayable conversation state, so they live in a `SessionHeader` owned by `dsh-session` and attached to a `Session` via a new readonly `session.header` — never in `SessionEventMap`, never reaching `deriveMessages()`. The alternative (a merge-extensible `session/meta` event as log line 0) was rejected: an in-log event would ride along with a seeded/forked session for free, but metadata is not replayable state, so the explicit out-of-log header seam is the cleaner cost. (The header was originally split into an immutable `SessionHeader` plus a mutable `SessionSummary` whose union was `SessionMeta`; the mutable summary was later removed as dead state — see [Drop the mutable session summary](../simplification/2026-06-19-drop-mutable-session-summary.md).)
- **Resume is an async factory, not a change to synchronous create.** `ctx.agents.resume({ resumeSessionId })` awaits `ctx.sessionPersistence.load`, recreates the live session with the loaded events (so `lastTurnNumber`/`deriveMessages` continue), and starts a fresh agent on the resumed id (NOT `${agentId}-session`). The agent-loop does NOT hard-inject `sessionPersistence` (that would pend non-persistent demos forever); `resume` rejects with a clear error when it is absent.
- **`ctx.agents.create()` and `ctx.agents.resume()` are async factories; resume additionally crosses the persistence boundary.** `ctx.agents.resume({ resumeSessionId })` awaits `ctx.sessionPersistence.load`, recreates the live session with the loaded events (so `lastTurnNumber`/`deriveMessages` continue), and starts a fresh agent on the resumed id (NOT `${agentId}-session`). The agent-loop does NOT hard-inject `sessionPersistence` (that would pend non-persistent demos forever); `resume` rejects with a clear error when it is absent.
## Alternatives considered
@@ -33,4 +31,4 @@ Format versioning: the header carries a `version`; `load` rejects any non-curren
## Consequences
Two new packages and the metadata seam in `dsh-session` (`session.header`, the `create(id?, options?)` signature). Bought: durable resume/fork, a read/replay path, crash tolerance, and the foundation the ACP `session/load` ([ACP support](../../proposed/feature/2026-06-14-acp-agent-client-protocol.md)) needs — all over the existing event-sourced log, with the backend swappable behind one interface. The reusable `runPersistenceContract` suite holds every backend to the same append-only / contiguous-seq / lazy-materialization / serializability semantics. This completes [event-sourced sessions](2026-06-11-event-sourced-sessions.md)'s deferred "real persistence backend" and resolves its `TODO(review)` on the event vocabulary: persisting the log freezes its shape, and the `assistant/chunk` fidelity question is answered above (persist verbatim).
Two new packages and the metadata seam in `dsh-session` (`session.header`, the `create(id?, options?)` signature). Bought: durable resume/fork, a read/replay path, crash tolerance, and the foundation the ACP `session/load` ([ACP support](../../implemented/feature/2026-06-14-acp-agent-client-protocol.md)) needs — all over the existing event-sourced log, with the backend swappable behind one interface. The reusable `runPersistenceContract` suite holds every backend to the same append-only, contiguous-seq, lazy-materialization, and serializability semantics. Persisting the full log also settles event fidelity: `assistant/chunk` remains verbatim.

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@@ -37,4 +37,4 @@ Costs: `agent.inject()` while idle now writes three log lines instead of one, an
The rule is intentionally producer-enforced and dev-checked rather than reader-tolerated: a future backend (SQLite/WAL) inherits the same clean boundary for free, and a plugin that records an event outside a turn fails loudly in dev instead of silently losing data on the next reload.
The invariant also constrains where the loop may record an `error` event. A failure detected while a turn is open is appended INSIDE the turn (before `turn/end`); but a failure that surfaces once the turn is already closed — a rejecting `session/flush`, which runs as the post-`turn/end` durability checkpoint — has no in-turn position left. Appending an `error` there would land it past the last `turn/end`, exactly the crash-tail position a backend discards. So that post-turn failure is reported via the `agent/error` event and the logger only, never as a `SessionEvent`; the turn stays balanced and persistence keeps its buffered events for the next checkpoint. If durable operational diagnostics are ever needed, they belong on a separate telemetry channel, not the replayable session log.
Failures detected during a turn are logged before `turn/end`. A later flush failure has no valid in-turn position, so it is reported through `agent/error` and logging rather than appended as a session event. This preserves a balanced replay log; durable operational diagnostics require a separate telemetry channel.

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@@ -34,7 +34,7 @@ The first consumer is deliberately text-file-only: `dsh-tool-fs` exposes model-f
Filesystem permissions and sandboxing are not implied by this split. The local backend resolves relative paths from its configured base directory, but containment policy is a separate decision: either a stricter `ctx.fs` implementation enforces it, or a permission/sandbox plugin wraps `tools/execute` and vetoes calls before they reach the consumer.
Read-before-write/edit and observed-state are policy, contributed by the `dsh-fs-policy` plugin through the `fs/*` event gate — NOT stored on `ctx.fs`. The provider seam offers an optional version guard on its mutations (`writeText`/`editText` take an optional expectation); the policy plugin decides that guard by listening on `fs/write-intent`/`fs/edit-intent` and records observed versions on `fs/observed`. The executor (`dsh-tool-fs`) passes the current tool execution context as the opaque event actor; the policy plugin derives the observed-state owner from it, normally `exec.agent.session`. `dsh-fs` treats the actor as opaque and never reads it; `dsh-tool-fs` never reaches into the policy plugin. Authorization is version freshness: any read records the file's version, and a later write/edit is authorized as long as the file is unchanged. (This RFC first placed the observed-state store on `ctx.fs`; the split to `dsh-fs-policy` on the `fs/*` event gate is decided by [the split-fs-seam](../simplification/2026-06-26-fsspec-style-fs-seam.md) and [event-gate](2026-06-26-file-context-as-event-gate.md) RFCs.)
Read-before-write/edit and observed state belong to `dsh-fs-policy`, not `ctx.fs`. Through the `fs/*` event gate, the policy records versions per opaque actor and supplies optional mutation expectations; the provider enforces freshness atomically. `dsh-tool-fs` emits the events without depending on the policy. See the [split-seam](../simplification/2026-06-26-fsspec-style-fs-seam.md) and [event-gate](2026-06-26-file-context-as-event-gate.md) RFCs.
## Package topology
@@ -81,7 +81,7 @@ Resolved targets must expose at least three concepts:
- An opaque `targetKey`, used for stale guards and file-state lookup. The local backend might use a realpath-like key; a remote backend might use a workspace URI or file id. Consumers must not parse or assume this is a local absolute path.
- A `displayPath`, used for model/UI-facing output. It may be a local absolute path, workspace-relative path, or remote URI depending on the backend.
Read and mutation results must include an opaque file `version`. A local backend can use mtime/size or a hash-like token; a remote backend can use a revision id. The `dsh-fs-policy` plugin records versions for stale checks; consumers may display related metadata but must not interpret the version token.
Read and mutation results must include an opaque file `version`. The local backend derives its token from bigint stat metadata (`dev`, `ino`, `size`, `mtimeNs`, and `ctimeNs`) so same-size rewrites and inode replacement invalidate consumers reliably; a remote backend can use a revision id or hash-like token. The `dsh-fs-policy` plugin records versions for stale checks; consumers may display related metadata but must not interpret the version token.
The provider hands back decoded text: `readText` returns a whole regular text file, `streamText` streams the same text semantics for large files. Both own regular-file checks, bounded line/output handling is NOT theirs — line windowing, numbered-line rendering, and total-line accounting live in the executor (`dsh-tool-fs`), which reads through `ctx.fs` and renders the model-facing window. The provider owns UTF-8 decoding and binary/NUL rejection; it does not know about line windows or views.

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@@ -12,37 +12,33 @@ Three seams: the queue-aware cancel, the `AgentHandle` disposer, and the bash ow
### 1. Queue-aware `Agent.cancel(reason?)`
A new `cancel()` verb on the `Agent` interface — the single public stop primitive. (It originally shipped alongside a narrower step-only `abort()`; that verb was later removed as unused, leaving `cancel()` the only public way to stop work.) It clears the inbox's queued + steering FIFOs, aborts the in-flight step if any, and drives a **turn-scoped cancellation marker** the driver loop checks at every turn-decision point — so a prompt that is queued-but-not-yet-started never runs, a cancel landing in the pre-step / continuation window drops the about-to-run turn (ending it `aborted`), and a later prompt cannot be batched into the cancelled turn. `whenIdle()` reaches post-cancel quiescence. ACP `session/cancel` maps to `cancel()`. The marker is armed ONLY when there is something to cancel, so an idle no-op cancel cannot strand the next prompt.
`cancel()` is the single public stop primitive. It clears queued and steering input, aborts an in-flight step, and arms a turn-scoped marker checked at each turn boundary. A queued prompt therefore cannot start after cancellation or absorb later input. `whenIdle()` waits for post-cancel quiescence, and ACP `session/cancel` maps to this method. An idle cancel does not arm the marker.
### 2. `AgentHandle` async disposer
`ctx.agents.create`/`resume` (and the `AgentFactory` interface) return `AgentHandle = { agent: Agent; dispose(): Promise<void> }`. The disposer is a **capability** — only the holder can tear down exactly this agent: stop its loop, `await` the loop's exit (true quiescence, not just the `disposed` status flip), unregister it, and remove its session from the store. `ctx.agents.get(id)` still returns a bare `Agent`. Config-created agents stay owned by the `AgentLoop` fiber (the handle is discarded). ACP holds each session's disposer in its `SessionRecord` and runs it on disconnect/teardown, so a bare client disconnect leaves no registered agent and no session-store entry — even when `session/load` races teardown (the just-resumed handle is disposed before the closed-guard throw).
`ctx.agents.create`/`resume` and `AgentFactory` return `AgentHandle = { agent, dispose() }`. Disposal is a consumer capability; an observer holding only `Agent` cannot tear it down. The caller fiber and factory provider also own the instance, and every path shares one memoized teardown: stop the loop, await quiescence and flushes, detach the agent and session, then unwind its scope. IDs become reusable when their registry entries detach. Config-created agents belong to the loop fiber; ACP stores and disposes each session handle.
**Teardown ORDER is load-bearing for durability**, and the implementation folds the session lifecycle into the agent's SINGLE composite cordis effect (`SessionStore.prepare`/`enter`/`announce`, replacing a sibling-effect split). A fiber unload disposes sibling effects concurrently (`Promise.all`), which would race the session's `onAppend` detach against the loop's closing `session/flush` and drop the closing `turn/end`; inside one effect the disposers run as an ordered LIFO chain (loop stopped + `await agent.done` BEFORE the session detaches), so the loop's final flush is captured on BOTH the handle's `dispose()` and a fiber unload. The register disposer's `agent/disposed` emit is contained (a throwing listener must not reject the chain and skip the later session detach).
Teardown order is load-bearing for durability. The session lifecycle and loop share one composite Cordis effect so LIFO disposal stops the loop and awaits `agent.done` before detaching the session. Sibling effects would dispose concurrently and could remove append hooks before the closing flush. Disposal notifications are contained so they cannot interrupt the chain.
### 3. Bash owner token in the seam
Background-task ownership moved from a `tool-bash` plugin-local `Map<string, Agent>` into the executor. `BashExecRequest` gains an optional `owner?: string`; the resolved `BashExecSpec` carries it as required-but-nullable `owner: string | undefined` (a forgotten owner is a visible `undefined`, never a silently-absent property). The executor stores the token on its task and exposes it via a new `BashExecutor.ownerOf(id): string | undefined` seam (NOT on the public `BashTask` — one read path, no redundant API). `tool-bash` deletes its `Map` entirely: it stamps `exec.agent?.session.header.id` as the owner at `start`, and `bash_output`/`bash_kill` compare `ctx.bash.ownerOf(id)` to the caller's token with `!== undefined` semantics (an empty-string token is still a real owner). The completion notice finds the live agent by scanning `ctx.get('agents')?.list()` for `agent.session.header.id === ownerToken` (read via `ctx.get``onTaskDone` runs on the bash fiber, a foreign fiber, where the `ctx.agents` proxy would throw). Because ownership now lives on the task in the executor (disposed with the `dsh-bash` fiber), it SURVIVES a `tool-bash` HMR reload — closing the old `XXX(tool-bash-owner-hmr)` gap. (The `onTaskDone` listener is still effect-scoped to `tool-bash`'s `apply`, so a completion landing during the reload gap still drops its one notice — the pre-existing reload-gap drop — but the ownership fence itself is HMR-proof.)
Background task ownership belongs to the executor. `BashExecSpec.owner` carries an optional opaque token, `ownerOf(id)` reads it, and `dsh-tool-bash` stamps the calling session token at start. `bash_output` and `bash_kill` reject mismatched callers; completion notices locate the live agent by session token through the registry. Keeping ownership on the task preserves the fence across tool-plugin reloads. The completion listener remains effect-scoped, so a notice that settles during the reload gap may still be dropped.
## Verification
These invariants hold and are pinned by tests:
- ACP disconnect or session close leaves no registered agent or session-store entry, including when `session/load` races teardown.
- Cancelling before a queued prompt starts prevents that prompt from running or absorbing the next prompt.
- Reloading `dsh-tool-bash` does not let another session read or kill an existing background task because ownership remains on the executor.
- Config-created agents remain loop-fiber-owned, so non-ACP demos need not manage handles explicitly.
- ACP disconnect/session close leaves no registered agent AND no session-store entry for that session, even when `session/load` races teardown.
- `session/cancel` before a queued prompt starts prevents that prompt from running and cannot batch the next prompt into the cancelled turn.
- A `tool-bash` HMR reload does NOT make an existing background task readable or killable by a different session (ownership survives on the executor).
- Existing non-ACP demos still work without managing handles explicitly; config-created agents remain owned by the `AgentLoop` plugin fiber.
## Session owner tokens are unique among live agents
## Seam precondition (recorded)
The bash owner-token comparison relies on `session.header.id` being unique among live agents. The agent registry does NOT enforce this — it rejects a duplicate *agentId*, not a duplicate session id, and `createAgent` accepts an arbitrary `sessionId`. This is NOT reachable via ACP (UUID sessionId, `agentId === sessionId`, duplicate-load rejected), so it is not a live product hole, but a programmatic caller that registers two agents with the same session id would break bash isolation and mis-route the completion notice. The access *policy* (token comparison) stays in `tool-bash` (the consumer); the bash seam stores only an opaque `owner` string and never interprets it — the correct interface/impl/consumer split.
The planned resolution is to remove the precondition by construction — see [unify the agent id and the session id](../../proposed/simplification/2026-06-20-unify-agent-and-session-id.md): once an agent IS its session (one id), the registry's existing unique-`agentId` check is a unique-session-id guarantee and no two live agents can share a session token.
The bash owner token relies on `session.header.id` being unique among live agents. Concurrent same-ID operations may prepare privately, but `SessionStore.enter()` rejects duplicate publication and the losing transaction rolls back. `tool-bash` owns the comparison policy; the bash seam stores an opaque `owner` string without interpreting it.
## Alternatives considered
- **A public `BashTask.owner` field** instead of the `BashExecutor.ownerOf(id)` seam — rejected: one read path, no redundant API.
- **Sibling cordis effects for the agent's session lifecycle** — rejected: a fiber unload disposes sibling effects concurrently (`Promise.all`), racing the session's `onAppend` detach against the loop's closing `session/flush`; the single composite effect's ordered LIFO chain is what captures the closing `turn/end` on both disposal paths.
- **Sibling cordis effects for the agent's session lifecycle** — rejected: a fiber unload disposes sibling effects concurrently (`Promise.all`), racing removal of the store-owned append publication hooks against the loop's closing `session/flush`; the single composite effect's ordered LIFO chain is what captures the closing `turn/end` on both disposal paths.
- **A separate step-only `abort()` beside `cancel()`** — shipped originally, then removed as unused; `cancel()` is the single public stop primitive ([the public-stop-surface RFC](../simplification/2026-06-20-public-agent-stop-surface.md)).
## Consequences

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@@ -4,7 +4,7 @@ Status: implemented
## Problem
The `Session` event log is the single source of truth ([event-sourced sessions](2026-06-11-event-sourced-sessions.md)), but the only view over it was `deriveMessages()` — a linear scan that filtered and transformed raw events into `Message[]`. This creates problems for session-history-manipulating plugins (compaction, tool-call result pruning, etc.). Without a central mechanism, each plugin would need to wrap `agent/request` to rewrite the message list — a pattern that suffers from listener-ordering fragility, provides no durable record of what was changed, and forces repeated changes to the core `deriveMessages()` whenever a new manipulation is added. A central hub in the `session` package, with a provenance-recording mechanism and enough flexibility for future plugins to manipulate session history through a stable API, lays a solid foundation for plugin development.
The event log is authoritative, but history manipulation had no durable shared mechanism. Plugins such as compaction would otherwise rewrite derived requests through order-sensitive listeners, leave no provenance, and require repeated changes to `deriveMessages()`.
## Decision
@@ -31,7 +31,7 @@ export type SurfaceOp =
### SurfaceManager: delta-based, not full rebuild
A `SurfaceManager` class (private to `Session`) maintains the cached linked list. It tracks `_lastProcessedSeq` and processes only the **delta** (new events since the last access) rather than rescanning the entire log. Because the log is append-only, prior events never change — full rebuild is only needed after a wholesale log replacement (e.g., seeding).
A `SurfaceManager` class (private to `Session`) maintains the cached linked list. It tracks `_lastProcessedSeq` and processes only the **delta** (new events since the last access) rather than rescanning the entire log. Because the log is append-only, prior events never change; a seeded log is simply the initial delta folded on first access.
Delta processing is O(1) when no new events and O(new events) when new events arrive.
@@ -49,7 +49,7 @@ The `repair.ts` module synthesizes `tool/result` closers for orphaned tool calls
The dev-mode invariants plugin validates: `sourceEventSeqs` references (non-empty, no duplicates, references earlier events, references known seqs) and `surfaceOp` (replace `start ≤ end`, both endpoints are on the tracked surface, the range is non-reversed in surface position, and `sourceEventSeqs` includes every node the range shadows).
Because the surface is the SOLE derivation path, a surface-eligible event that carries no `surfaceOp` marker is invisible to `deriveMessages()` — it would land in the log yet silently drop from history on resume/fork. `append`'s typed overload makes the marker mandatory for `SurfaceEventType` events at compile time, but only when the type argument is a SPECIFIC literal; when it widens to the `SessionEventType` union (a caller iterating raw events, e.g. `for (const e of log) append(e.type, e.data)`) the conditional rest collapses to optional and the compiler stops enforcing it. The marker requirement is therefore ALSO checked at runtime in two places: `append` itself throws on a marker-less surface-eligible event (covering the union-widening loophole), and the `Session` seed constructor re-checks the same invariant (alongside its seq-contiguity and JSON-serializability checks) so a seed/load/fork — which arrives as raw `SessionEvent[]`, bypassing `append` — is REJECTED rather than constructing a session that resumes with missing history. (No backward-compat path for surface-less logs: per the pre-release stance there is no persisted user data to preserve, so such a log is rejected, not upgraded.)
Every surface-eligible event must carry `surfaceOp` or it would disappear from derived history. Typed `append` overloads enforce this for literal event types; runtime checks in `append` and the seed constructor cover widened unions and loaded logs. Invalid seeds are rejected rather than upgraded under the pre-release format policy.
## Alternatives considered

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@@ -39,4 +39,4 @@ The shared `runPersistenceContract` (public-API contract) keeps running for ever
## Consequences
The pre-extraction duplication was verbose but explicit — each backend read top-to-bottom. The coordinator adds one indirection (the hook seam) and one new concept (the opaque torn marker). This clears the bar because the centralized logic is the correctness-heavy part that was already being fixed twice, and the hook set is narrow (six methods, no inheritance). The hook surface was deliberately held to the minimum: the create-collision probe is NOT a separate hook — it folds into `loadStored(id) !== undefined`; there is no separate `materialize` hook (folded into `appendBatch` for atomicity); `list()` stays a backend method with no coordinator pass-through (listing needs none of the orchestration). The net effect is a reduction: one orchestration copy instead of two, the backends shrank by ~1200 lines of duplicated churn, and a future backend implements a handful of small primitives instead of copying the entire `session/event`bufferflush machinery.
The coordinator adds one indirection and an opaque torn marker, but centralizes correctness-heavy orchestration previously duplicated by every backend. Its hook surface stays narrow: collision checks reuse `loadStored`, materialization stays atomic inside `appendBatch`, and listing bypasses the coordinator. New backends implement storage primitives rather than copy the event-buffer-flush lifecycle.

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@@ -6,11 +6,11 @@ Status: implemented
The harness already brands three identifiers — `CallId` (`packages/llm/llm/src/brand.ts`), `SessionId` (`packages/core/session/src/types.ts`), and `AgentId` (`packages/core/agent/src/types.ts`) — using the `Branded<B> = string & { readonly [BRAND]: B }` machinery (owned by the type-only `@deepseek-ai/dsh-brand` package at `packages/util/brand/` — see its [README](../../../../packages/util/brand/README.md)) and a zero-cost cast factory per type. `dsh-brand` also states the governing policy: *"Branding is for ids that cross package boundaries and could plausibly be confused; not every string needs a brand."* That policy is right; the problem is that it is only half-applied. Two gaps let a structurally-identical-but-semantically-wrong string slip through the type checker today.
**Gap 1 — unbranded cross-boundary IDs in the bash seam.** The background-task id is a plain `string`: `BashTask.id: string` (`packages/bash/bash/src/types.ts`), carried as `string` through the whole executor seam (`BashExecutor.get`/`ownerOf`/`readOutput`/`kill(id: string)` in `packages/bash/bash/src/index.ts`) and validated/passed as `string` by the model-facing tools (`validateTaskId`, `assertTaskAccess`, the `task_id` schema arg in `packages/bash/tool-bash/src/index.ts`). It is generated by a per-executor counter — `` `bash-${this.nextTaskId++}` `` in `packages/bash/bash-local/src/index.ts` — which gives it **exactly the same `name-N` shape as `SessionId`'s default** (`` `session-${++counter}` `` in `packages/core/session/src/index.ts`). A bash task id and a session id are trivially swappable at a call site and the compiler says nothing. This is the headline case the user asked about, and it is a model-facing id (the model passes `task_id` back to `bash_output`/`bash_kill`), so a confusion here is reachable from untrusted input.
**Gap 1 — unbranded IDs in the bash seam.** `BashTask.id` and every executor/tool boundary used bare `string`, even though the generated value has the same `name-N` shape as default session ids. The model also returns this value through `task_id`, so confusing task and session ids was both type-correct and reachable.
The bash **owner token** is the related sub-case: `BashExecRequest.owner?: string` and `BashExecSpec.owner: string | undefined` (`packages/bash/bash/src/types.ts`) are documented as a deliberately *opaque* isolation key, but in every live caller the value IS the owning agent's `session.header.id` (`callerToken = (exec) => exec.agent?.session.header.id` in `packages/bash/tool-bash/src/index.ts`) — i.e. a `SessionId` wearing a `string` disguise. It is compared for access control (`owner !== callerToken(exec)`), so a mismatched-but-well-typed string here is a cross-session isolation bug the type system currently cannot catch. This is the same `session.header.id`-as-owner alias that the [unify-the-agent-id-and-the-session-id](../../proposed/simplification/2026-06-20-unify-agent-and-session-id.md) proposal calls the "bash owner-token alias hole".
**Gap 2 — brand erosion at the seams of the *already-branded* IDs.** Even `CallId`/`SessionId`/`AgentId` decay back to bare `string` at exactly the places confusion is most likely: the registry/store `Map` key types and most public method params. Representative sites: `SessionStore.store = new Map<string, Session>()` and `create`/`prepare(id?: string)`/`get(id: string)` (`packages/core/session/src/index.ts`); `AgentRegistry.store = new Map<string, Agent>()` and `register`/`get(id: string)` (`packages/core/agent/src/index.ts`); `ToolPresenter.pending = new Map<string, …>()` keyed by call id and `call(callId: string)`/`result(callId: string)` (`packages/ui/acp/src/index.ts`); the ACP session-id surface beyond the store map — `SessionRecord.sessionId: string`, `bySession = new WeakMap<Agent, string>()`, `loadingIds = new Set<string>()`, `requireSession(sessionId: string)`, and the exported `streamSessionEventUpdate(sessionId: string, …)` (`packages/ui/acp/src/index.ts`); and the persistence coordinator's `Map<string, …>` keyed by session id (`packages/session-persistence/session-persistence/src/coordinator.ts`). A brand that is dropped at the `Map` key buys nothing on lookups — the value of the existing brands is partly unrealized.
**Gap 2 — erosion of existing brands.** `CallId`, `SessionId`, and `AgentId` became bare strings in registry maps, public lookup parameters, ACP session tracking, and the persistence coordinator. Dropping a brand at a lookup boundary defeats its main protection.
## Decision
@@ -44,7 +44,7 @@ export function OwnerToken(id: string): OwnerToken {
### Why not typing `owner` as `SessionId`?
The obvious shortcut is to type `owner` as `SessionId` directly — it always *is* one. We reject that. The bash executor seam is a capability seam (interface `dsh-bash`, implementation `dsh-bash-local`, consumer `dsh-tool-bash`) and its owner token is *documented as deliberately opaque*: the executor "never interprets it (no access policy lives in the seam — that is the consumer's job)" (`packages/bash/bash/src/types.ts`). Typing the seam's field as `SessionId` would import `dsh-session`'s vocabulary into a package that must not know what an owner token *means* — it would couple a generic execution backend to the session model and contradict the opaque-token design. A sandboxed or remote executor that replaces `dsh-bash-local` should not inherit a session dependency. The distinct `OwnerToken` brand keeps the seam decoupled: `dsh-bash` knows only "an owner is some opaque branded token," and the `dsh-tool-bash` consumer — which already decides the access policy — is the single boundary that casts its `SessionId` into an `OwnerToken`. The brand still delivers the safety win (you cannot pass a `BashTaskId` or a raw string where an owner is expected) without the coupling.
The executor treats ownership as opaque and must not depend on the session model. A distinct `OwnerToken` preserves that boundary while preventing raw strings or task ids from being passed as owners. `dsh-tool-bash`, which owns the access policy, performs the single conversion from `SessionId`.
## Out of scope / possible extensions
@@ -58,7 +58,7 @@ Kept deliberately narrow per the "not every string needs a brand" policy. Each o
## Verification
The landed invariants: `BashTaskId` and `OwnerToken` are defined in `dsh-bash` and threaded end-to-end (executor seam, the `dsh-bash-local` generation site, the `dsh-tool-bash` model-facing surface) with no `dsh-bash` dependency on `dsh-session`; no collection keyed by an in-scope branded id (`CallId`/`SessionId`/`AgentId`/`BashTaskId`) is keyed by bare `string` — `Map` keys, `WeakMap` value slots, `Set` membership (the ACP `bySession`/`loadingIds`), public method params, and exported signatures (`streamSessionEventUpdate`) all take the brand; and brands are constructed via the cast factory at each boundary where a raw string enters (provider call id, ACP session id, model-supplied `task_id`), never as scattered `as` casts.
`BashTaskId` and `OwnerToken` are defined in `dsh-bash` and threaded through the executor, local implementation, and model-facing tool without adding a `dsh-session` dependency. Collections, public parameters, and exported signatures use the applicable brand for `CallId`, `SessionId`, `AgentId`, or `BashTaskId` rather than bare `string`; raw provider, ACP, and model inputs enter through the brand factory instead of scattered casts.
## Consequences

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@@ -6,24 +6,24 @@ Status: implemented
An example folder is supposed to be *thin* — the variable wiring of a demo, not the demo's machinery. Before this change it was thick. Each example carried a hand-rolled `start.ts` boot bootstrap, an infra preamble (`timer`, and — for the stdio demos — `logger` + `hmr`), nested includes of three shared YAML fragments (`base.yml` / `base-core.yml` / `acp-agent/acp-tail.yml`), and per-example `agent-loop`/persistence/system-prompt config. The actual app — the spine of services every agent needs — was spread across the leaf and those includes.
The deeper problem was a **coupled front-door cluster** that lived at the leaf with nothing enforcing it. Choosing the ACP bridge over `ui-stdio` was not one swappable line: an ACP server must **drop the stdout console logger** (stdout is the JSON-RPC channel — a stray log corrupts the frames) and pre-create **no** agents (ACP `session/new` creates them on demand), whereas the stdio app needs a console logger and a pre-created `main`. (`timer` is the one infra plugin common to both — it writes nothing to stdout — so it belongs in the shared spine, not the cluster.) That coupling was enforced only by prose warnings in the leaf YAML. A leaf that wired a console logger into the ACP config was a one-line, comment-only mistake away — exactly the [stdout-purity footgun](../feature/2026-06-18-acp-terminal-and-tool-rendering.md) the examples guarded by hand. The three `start.ts` files also duplicated the Loader-boot tail, the `.env` loader, and (for ACP) snapshot-mode branching and the stdin-dispose lifecycle.
The leaf configs also owned a coupled front door. ACP requires stdout purity and creates agents through `session/new`; stdio requires a console logger and a pre-created `main`. Prose warnings were the only guard against combining these incorrectly, while three `start.ts` files duplicated the Loader bootstrap and lifecycle code.
## Decision
Each example is now **mostly an invocation of an app package**, splitting the wiring along the existing [interface / implementation / consumer seam](2026-06-13-capability-seams.md): the **app package owns the composition**, the leaf `cordis.yml` owns only the **swappable choices** (which LLM adapter, which bash executor, model, prompt, persistence root).
- **`@deepseek-ai/dsh-agent-core`** ([packages/core/agent-core](../../../../packages/core/agent-core)) — a Cordis bundle plugin for the providerless, executor-less, UI-less spine: `timer` + `llm` + sessions + system-prompt + tools + agents + invariants + `tool-bash` + `agent-loop`, mounted as child plugins inside its `apply(ctx)` via `ctx.plugin(...)`. This is the old `base-core.yml` **minus** `bash-local`, **plus** `timer` and the loop, as code instead of a YAML include. The bundle **forwards** `agent-loop`'s `agents` list as its own config (`export const Config = AgentLoop.Config`, default `[]`, the existing `AgentLoop.Config` shape in [packages/core/agent-loop/src/index.ts](../../../../packages/core/agent-loop/src/index.ts)) — so each app supplies its own pre-created agents. This is precisely the reason the old `base-core.yml` gave for keeping `agent-loop` *out* of the shared core ("the examples disagree — stdio needs a pre-created `main`, acp needs none"); forwarding the config dissolves that objection — the loop is shared, the agents list is per-app. The bundle children register into the root service store, so a leaf-mounted sibling (the adapter, the executor) sees them exactly as a nested `plugin-include` subtree's services were seen before. Depending on the CONCRETE `dsh-agent-loop` (not just the `dsh-agent` interface) is deliberate and is the sanctioned exception to the "extension plugins depend on interfaces, never on the concrete loop" rule (packages/README.md, docs/architecture.md § Service map): the rule constrains plugins that EXTEND the system, whereas this bundle's whole job is to COMPOSE the concrete spine. Swapping the loop means publishing a different bundle, not rewiring every extension.
- **`@deepseek-ai/dsh-stdio-agent`** ([packages/ui/stdio-agent](../../../../packages/ui/stdio-agent)) and **`@deepseek-ai/dsh-acp-agent`** ([packages/ui/acp-agent](../../../../packages/ui/acp-agent)) — app packages, each consuming `dsh-agent-core` and **baking in its coupled front-door cluster**: stdio = `ui-stdio` + console logger + a pre-created `main`; acp = the `acp` bridge + JSONL persistence + **no stdout logger** + no pre-created agents. The leaf no longer carries the cluster, so it has no logger entry to copy wrong by default — the common stdout-purity mistake loses its foothold. (A leaf can still *add* a sibling logger entry — a package cannot forbid what a leaf author writes — so the rule "never add a stdout logger to an ACP leaf" stays documented at the leaf; what changed is that the default leaf has nothing to get wrong.) They land under the existing `ui` group alongside `acp`, so no new package group (and no `tsconfig`/`packages/README` group plumbing) was needed.
- **`start.ts` is gone.** Each app package exposes a `bin` (`dsh-stdio-agent` / `dsh-acp-agent`); the `demo:*` scripts invoke it (e.g. `dsh-stdio-agent ./cordis.yml`). The Loader-boot tail, `.env` loading, and fail-loud guards live in the shared [`@deepseek-ai/dsh-app-boot`](../../../../packages/ui/app-boot) package (unit-tested under the per-file coverage gate — see [share the app bins' boot glue](../simplification/2026-07-04-share-app-bin-boot-glue.md)); each bin is a thin self-executing composition over those helpers plus its app-specific lifecycle (the ACP bin: snapshot-mode selection and stdin-dispose). The `bin.ts` files themselves stay coverage-excluded (self-executing CLI entries, like the old `start.ts`) and are driven by the keyless Loader-path tests.
- **`@deepseek-ai/dsh-agent-spine-demo`** ([packages/examples/agent-spine-demo](../../../../packages/examples/agent-spine-demo)) composes the providerless, executor-less, UI-less spine and forwards the loop's agent-list config. Its dependency on the concrete loop is intentional because this package composes the spine rather than extending it; swapping the loop means supplying another bundle.
- **`@deepseek-ai/dsh-stdio-demo`** ([packages/examples/stdio-demo](../../../../packages/examples/stdio-demo)) and **`@deepseek-ai/dsh-acp-demo`** ([packages/examples/acp-demo](../../../../packages/examples/acp-demo)) bake in their front doors. Stdio includes `ui-stdio`, a console logger, and `main`; ACP includes the bridge and JSONL persistence but no stdout logger or pre-created agent. Leaves may add plugins, but the safe composition is now the default artifact.
- **`start.ts` is gone.** Each app package exposes a `bin` (`dsh-stdio-demo` / `dsh-acp-demo`); the `demo:*` scripts invoke it (e.g. `dsh-stdio-demo ./cordis.yml`). The Loader-boot tail, `.env` loading, and fail-loud guards live in the shared [`@deepseek-ai/dsh-app-boot`](../../../../packages/ui/app-boot) package (unit-tested under the per-file coverage gate — see [share the app bins' boot glue](../simplification/2026-07-04-share-app-bin-boot-glue.md)); each bin is a thin self-executing composition over those helpers plus its app-specific lifecycle (the ACP bin: snapshot-mode selection and stdin-dispose). The `bin.ts` files themselves stay coverage-excluded (self-executing CLI entries, like the old `start.ts`) and are driven by the keyless Loader-path tests.
- **Each leaf `cordis.yml` collapses** to backends + config: the LLM adapter (`llm-deepseek` with apiKey/models, or `llm-replay`), the bash executor (`bash-local`), `hmr` for the stdio demos (see the amendment below), and one app entry carrying the app's config (model, system prompt, persistence root — surfaced as the app package's own `Config`, which routes each value to wherever the app wires it: stdio onto its pre-created agent, acp onto the bridge plugin).
- **echo-agent folds onto `dsh-stdio-agent`**, swapping the LLM backend to the local `mock-llm` and adding the local `echo-tool` (plus `bash-local`, which the spine's `tool-bash` injects) at the leaf — the clean demonstration of "swap the backend, keep the app". `mock-llm.ts` / `echo-tool.ts` stay as example-local teaching plugins.
- **`base.yml`, `base-core.yml`, and `acp-agent/acp-tail.yml` are retired** — the spine they shared now lives in `dsh-agent-core`.
- **echo-agent folds onto `dsh-stdio-demo`**, swapping the LLM backend to the local `mock-llm` and adding the local `echo-tool` (plus `bash-local`, which the spine's `tool-bash` injects) at the leaf — the clean demonstration of "swap the backend, keep the app". `mock-llm.ts` / `echo-tool.ts` stay as example-local teaching plugins.
- **`base.yml`, `base-core.yml`, and `acp-agent/acp-tail.yml` are retired** — the spine they shared now lives in `dsh-agent-spine-demo`.
`bash-local` and the LLM adapter stay **leaf choices**: the bundle ships `tool-bash` (the consumer schema), the leaf picks the executor implementation, so a sandboxed executor or replay adapter swaps in without touching the app.
### Amendment on implementation: `hmr` stays a leaf entry
The proposal listed `hmr` among the stdio app's baked-in front-door cluster. Validating against the code, baking `hmr` into the `dsh-stdio-agent` package fights cordis in two ways, so it ships as a **leaf `cordis.yml` entry** instead:
The proposal listed `hmr` among the stdio app's baked-in front-door cluster. Validating against the code, baking `hmr` into the `dsh-stdio-demo` package fights cordis in two ways, so it ships as a **leaf `cordis.yml` entry** instead:
1. `@cordisjs/plugin-hmr` is a Loader-only, subprocess-only dev plugin — its constructor throws without `node --expose-internals` + a live `loader` service, so it can only run in the real `demo:*`/bin subprocess, never in the in-process unit/coverage tier.
2. The in-process test tier (vitest) cannot even *import* the vendored `hmr` module (its class-decorator `@Inject` form fails under Vite's transform), so a package whose `apply` statically imported it could never satisfy the per-file 100% coverage gate on its headline function.
@@ -38,18 +38,18 @@ The old `base*.yml`/`acp-tail.yml` includes already deduped the *config*, but a
## Verification
- Each example directory is `cordis.yml` (+ the acp `cordis.snapshot.yml`) + `README.md` + tests only — no `start.ts`, no infra preamble; `base.yml`/`base-core.yml`/`acp-tail.yml` are gone.
- `demo:echo` / `demo:repl` / `demo:acp` run via the app-package `bin`s.
- The new packages carry the per-file 100% coverage gate and a README like every `@deepseek-ai/dsh-*`. Each app package has a keyless **real-load-path** smoke that boots it through its `bin` + the cordis Loader (not a hand-built `ctx.plugin({...})` mount), guarding the `unwrapExports` export-shape bug class ([postmortem 0001](../../../postmortem/0001-acp-default-export-drops-inject.md)).
- The ACP snapshot **replay** transcript is unchanged: the boot restructuring preserved the plugin set + load order, so `pnpm run test:snapshot` stays green against the committed goldens with no re-record.
- Example directories contain only their config, README, and tests: `start.ts`, the infrastructure preamble, and the shared YAML includes are gone.
- `demo:echo`, `demo:repl`, and `demo:acp` invoke the app-package bins.
- Each new package has a README and per-file 100% coverage; each app package also has a keyless real-Loader-path bin smoke that catches export-shape failures described in [postmortem 0001](../../../postmortem/0001-acp-default-export-drops-inject.md).
- The ACP replay transcript remains unchanged because the plugin set and load order did not change.
## Consequences
- **The bare-plugin-tree pedagogy.** echo-agent's inlined `cordis.yml` showed every plugin at once; the spine now lives behind a bundle, so seeing the whole tree means opening `dsh-agent-core`. The app package's README carries that teaching weight.
- **The bare-plugin-tree pedagogy.** echo-agent's inlined `cordis.yml` showed every plugin at once; the spine now lives behind a bundle, so seeing the whole tree means opening `dsh-agent-spine-demo`. The app package's README carries that teaching weight.
- **A layer of indirection.** "What does this demo load?" becomes a package read, not a single YAML scan.
## Related
- Supersedes [Make the shared example base providerless](../../rejected/architecture/2026-06-20-providerless-example-base.md): renaming `base.yml` to the providerless core is moot once the spine moves into `dsh-agent-core` and the `base*.yml` files are deleted.
- Supersedes [Make the shared example base providerless](../../rejected/architecture/2026-06-20-providerless-example-base.md): renaming `base.yml` to the providerless core is moot once the spine moves into `dsh-agent-spine-demo` and the `base*.yml` files are deleted.
- Builds on the [capability-seams](2026-06-13-capability-seams.md) interface/implementation/consumer split — backends and presentation stay leaf choices; the spine is the shared bundle.
- Complements [Reorganize packages into a modular hierarchy](2026-06-20-package-hierarchy.md): the new app/core packages slot into existing groups under that hierarchy (`core` for the reusable spine bundle, `ui` for the app-specific front doors).

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@@ -0,0 +1,128 @@
# RFC: The background task runtime (`ctx.tasks`) and generic task control tools
Status: implemented
## Problem
Background bash originally combined two responsibilities: the bash executor ran processes and also managed task ids, ownership, incremental reads, cancellation, completion listeners, and model-facing control tools. Adding background subagents required the same lifecycle and interaction contract. Implementing that contract independently for every long-running capability would duplicate isolation, cleanup, notification, and prompt behavior while teaching the model a different collect-and-stop protocol for each producer.
The task registry, control tools, and completion notices form one harness capability. Bash and subagents should supply execution-specific hooks without owning generic task behavior.
## Decision
The `tasks/` package group owns background-task semantics:
- `@deepseek-ai/dsh-tasks` registers running work as `ctx.tasks` and owns task ids, authorization, snapshots, reads, cancellation, waiting, completion listeners, and cleanup.
- `@deepseek-ai/dsh-tool-tasks` exposes `task_output`, `task_list`, and `task_kill`, injects completion notices, and supplies the background-task system-prompt guidance.
Long-running tools are producers. `dsh-tool-bash` adapts a `BashProcess` into incremental output and process cancellation; `dsh-tool-subagent` adapts a child run into final output and child disposal. The execution seams remain independent of sessions and the task registry.
`TaskService` is a concrete, process-local service. TODO(task-service-backend): separate its public contract from the implementation when a second backend defines the required lifecycle; a systemd-backed runtime is one plausible driver, but this PR does not speculate about its durability, reconnect, ownership, or observation semantics.
## Runtime contract
The literal types live in the [task data-structure catalog](../../../core-data-structures/tasks.md). A producer calls `ctx.tasks.start()` with a kind, label, optional owning `Agent`, and a `run()` function. The runtime completes all failable preflight work before calling `run()` and invokes it once. After `run()` returns hooks, registration commits without another failable step; a producer cannot start work that lacks a collectable task id.
The producer hooks define three responsibilities:
- `cancel(reason?)` synchronously requests termination, is idempotent, and must cause `done` to settle.
- `done` never rejects and settles only after the producer has released the task's resources.
- Optional `readOutput()` returns the next consuming output delta. Omitting it declares a final-output task whose terminal result comes from `TaskOutcome.output`.
Statuses are `running`, `stopping`, `completed`, `killed`, and `failed`. Producer-specific information such as an exit code or stop reason belongs in `detail`; the registry does not interpret it. Task kinds form a merge-extensible string union, and task ids are branded and generated as `<kind>-N`, with a counter per kind.
The runtime attaches one continuation to `done`, records the first terminal outcome, resolves waiters, and invokes completion listeners with per-listener error containment. First-wins settlement matters during teardown: if `cancel` throws, the runtime force-fails the record and warns that work may be orphaned rather than waiting forever for a promise that may never settle. A later producer outcome cannot overwrite that diagnosis or notify twice. A `cancel` that returns without eventually settling `done` still blocks teardown because the runtime cannot distinguish it from a slow, valid stop.
Task registrations are not effects of the producer tool fiber. Reloading a tool or control-surface plugin therefore does not kill work owned by an agent and backend. The task service's own disposal cancels all live tasks and awaits contract-compliant producers.
## Authorization and owner lifecycle
Task ids are runtime-global and predictable, so every access is authorized by the registry. `get`, `read`, `wait`, and `kill` accept the calling `Agent`; `list` returns only tasks visible to that caller. An owned task is accessible only to the exact owning session. Unowned tasks are open to non-agent callers and die with the task service.
The snapshot stores the owner's branded `SessionId` for authorization, while lifecycle operations retain the exact live `Agent` instance. These identities serve different purposes: session equality grants access, but exact object identity selects cleanup and completion delivery. Reusing an agent or session id cannot redirect an old scope's cleanup or notices to a replacement.
The first task for an owner attaches one asynchronous effect to `owner.ctx`. Agent-scope disposal cancels that owner's live tasks, awaits their terminal records, and removes their snapshots. This effect survives producer reloads and joins the agent's existing quiescence boundary. The task service retains the effect disposer so service reload can detach callbacks from still-live agent scopes after global teardown.
For contract-compliant producers, `AgentHandle.dispose()` resolves only after owned background work has stopped. Work intended to outlive an agent must be started unowned; survival across runtime restarts requires a separate durable-job design.
## Service surface
`TaskService` provides:
- `start(spec)` for preflighted, atomic registration.
- `get(id, caller?)` and `list(caller?)` for non-consuming snapshots.
- `read(id, caller?)` for a consuming stream delta or an idempotent final result.
- `kill(id, caller?, reason?)` for cancellation.
- `wait(id, timeoutMs, caller?, signal?)` for bounded terminal waiting.
- `onTaskDone(listener)` for effect-scoped observation with exact-owner delivery and listener containment.
- `attachSurface(name)` for the control-surface availability fence.
`wait` returns the terminal snapshot when the task settles or the live snapshot when its timeout expires. Aborting a wait cancels only that wait. If settlement has already assigned terminal delivery to the waiter, the terminal snapshot still wins. Waiters unregister synchronously on abort so a same-tick settlement cannot suppress a completion notice on behalf of a reader that receives nothing.
A producer loaded without any control surface would let callers start work they cannot collect or stop. `dsh-tool-tasks` therefore calls `attachSurface()` for its lifetime, and `start()` fails before producer execution when no surface is attached. This check occurs at start rather than plugin load because sibling plugins may activate concurrently. Custom non-model surfaces can attach themselves without teaching the registry tool names.
## Model-facing control surface
`dsh-tool-tasks` registers three kind-independent tools with generic ACP cards:
- `task_output(task_id, wait?, timeout_ms?)` reads output and always appends `[status: ...]`. Stream tasks return only output since the previous read; final-output tasks return their result after settlement. Reads are non-blocking unless `wait: true`, whose timeout is defaulted and capped by plugin config. A wait timeout reports the still-running status and does not stop the task.
- `task_list()` returns caller-visible tasks as `<id> [<kind>] <status> — <label>`, or `(no background tasks)`.
- `task_kill(task_id, reason?)` requests cancellation immediately. The optional logged reason is forwarded to the producer. Terminal tasks report their existing status; a throwing producer cancel fails the call and leaves the task running.
Stream reads share one task-scoped consuming cursor because the owning model is the intended reader. A UI or multiple independent readers need a separate non-consuming observation API; sharing this cursor would let readers consume one another's output.
The system prompt tells the model to retain task ids, continue independent work instead of busy-polling or duplicating a running task, collect relevant tasks before its final answer, and kill work that no longer matters. Completion injects a logged `context/message` into the exact owner's session; it becomes durable context for the next request but does not wake an idle agent.
The runtime marks a terminal task `reported` when a read or wait delivers it, when a live waiter has claimed delivery at settlement, or when the model explicitly kills it. Reported tasks do not inject redundant completion notices. Listener failures are logged independently, do not stop later listeners, and are not awaited by waiters or teardown.
## Producer opt-in
Each producer owns whether its schema exposes `run_in_background` through defaulted config. `dsh-tool-bash` and each `dsh-tool-subagent` instance use `enableRunInBackground`, defaulting to true. A disabled instance omits the parameter and also rejects a forced background argument at execution because the generic argument validator permits undeclared keys. Schema omission advertises the capability; the execution check enforces it.
`ctx.tasks` does not rewrite producer schemas. A bundle forwards configuration only for producers it owns. If a background call reaches `start()` without an attached surface, the runtime fence fails before execution.
## Producer integrations
The bash seam exposes `resolve`, `run`, and `start`. `start(spec)` returns a `BashProcess` with incremental reads, cancellation, exit facts, and a non-rejecting quiescence promise. The local executor retains live handles only so its own disposal can kill and join processes. Foreground callers continue to use `resolve` and `run` directly.
For background bash, `dsh-tool-bash` registers the calling agent as owner. Its hooks map `kill()` to cancellation, `done` to a completed or killed `TaskOutcome`, and `readOutput()` to the process's bounded incremental output plus spill and sandbox notices. Generic task tools own ids, status lines, listing, waiting, and completion notices.
For background subagents, `dsh-tool-subagent` creates a task-owned `AbortController` and begins provider startup inside the task starter. Cancellation aborts the same signal before or after provider readiness. `done` awaits both the child result and child disposal, maps completed output to a final result, maps abort to `killed`, and maps other stop reasons or infrastructure failures to `failed`. Intermediate child history remains in the child session and is not exposed through `readOutput()`.
## Alternatives considered
### Per-capability control tools
Separate bash and subagent output/stop tools duplicate ids, isolation, cleanup, notification, and guidance while increasing the model's schema and protocol burden. One runtime keeps execution-specific behavior in producers without cloning the task lifecycle.
### An immediate abstract task-runtime backend
The current `TaskStart.run()` contract passes in-process callbacks and exact `Agent` objects. A durable backend changes identity, restart, ownership, and observation semantics, so extracting an interface before a second implementation exists would freeze the wrong boundary.
### Consumer-owned authorization or cleanup events
Consumer-owned checks invite inconsistent or missing isolation on each new surface. A broadcast cleanup event makes every listener filter every agent and provides no registration disposer. Central authorization plus one owner-scoped effect gives every consumer the same fence and an awaited, removable lifecycle hook.
### Blocking output or a separate wait tool
Blocking by default would serialize the parent while background work runs. Waiting without reading would add another model call and schema without returning useful information. `task_output(wait: true)` makes blocking explicit and combines it with result delivery.
The wait uses the shared deadline primitives but not the generic tool-timeout policy. A wait timeout is a successful observation that returns `[status: running]`; the generic policy would replace it with a timeout error. No tool-call timeout controls task lifetime after a task id has been returned.
### Runtime-owned output sinks
A push sink would centralize buffering, but bash already owns bounded buffers, truncation, and spill files behind its executor seam. Pulling formatted deltas preserves that ownership. A durable backend that owns storage may justify revisiting the producer interface.
### Random ids, promotion, or lifecycle session events
Authorization, not unguessability, is the access boundary, and ids do not derive filesystem paths; sequential branded ids keep transcripts readable. Foreground-to-background promotion requires a user interaction contract the SDK does not prescribe. Starts, reads, and notices are already logged as tool and context events, so dedicated task session events would duplicate model-visible facts.
## Testing
Unit coverage pins preflight atomicity, per-kind ids, stream and final reads, wait timeout and abort races, cancellation, first-wins settlement, listener containment, notice suppression, owner isolation, stale owner instances, owner cleanup, service teardown, and the no-surface fence. Producer tests cover bash process mapping, subagent startup cancellation, terminal mapping, and disposal. Snapshot coverage pins the control-tool schemas and prompt guidance.
## Consequences
Bash commands and subagents share one id vocabulary, listing, notice format, prompt habit, and set of control tools. New long-running producers implement execution hooks instead of another registry and tool family. The [tool cookbook](../../../cookbook/adding-a-tool.md) points producers to this contract.
Owned background bash now stops with its agent instead of surviving it. Background processes have no executor timeout; callers must kill irrelevant work or rely on owner/service disposal. Stream reads support one consuming reader, completion notices do not wake idle agents, and a producer that returns from `cancel` without settling `done` can still stall teardown. Durable jobs, independent observation cursors, and foreground promotion remain separate designs.

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@@ -12,7 +12,7 @@ The immediate prompt came from OpenRouter's [App Attribution](https://openrouter
- **OpenRouter's mechanism is provider-specific.** Their current docs say app attribution is tracked through `HTTP-Referer` (required), `X-OpenRouter-Title`, and `X-OpenRouter-Categories`; `X-Title` is only accepted for backward compatibility. Their API reference calls the headers optional and says they make the app discoverable on OpenRouter. This is a concrete OpenRouter contract, not an IETF or OpenAI-compatible API standard.
- **In agent tooling, `HTTP-Referer` is an OpenRouter-aware convention, not a general agent convention.** It is common enough that OpenRouter SDKs and OpenRouter examples expose it directly, and frameworks that target OpenRouter usually need a way to pass it through. But agent protocols such as ACP negotiate names, versions, and capabilities in their own initialize messages, while model-provider requests still need HTTP-level identity. "Accepted in the agent world" therefore means "recognized by OpenRouter integrations," not "portable across agent runtimes or providers."
- **Observed coding agents use product/version `User-Agent` strings, sometimes with environment context.** A non-exhaustive public-code survey found OpenAI Codex building `{originator}/{version} ({os} {os_version}; {arch}) ...` and carrying an `originator` header; Google Gemini CLI sending `GeminiCLI[-clientName]/{version}/{model} ({platform}; {arch}; {surface})` or a Cloud Code VS Code variant; Cline's Codex backend client sending `cline/{version} ({platform} {release}; {arch}) node/{nodeVersion}` plus `originator: cline`; SWE-agent setting `swe-agent/{version}` unless the user already supplied a header; Continue setting `Continue/{version}` for its ClawRouter provider plus `X-Continue-Provider`. Aider also appends `Aider/{version} +{website}` to browser-like user agents for web scraping, but that is not a model-provider request path. The pattern is not one exact format; it is product identity in `User-Agent`, with provider-specific side headers only where a provider/backend asks for them.
- **Coding agents identify the product and version in `User-Agent`.** Public implementations vary in environment detail and provider-specific side headers, but product identity is the common contract; there is no universal exact format.
- **The standards-track general client identity header is `User-Agent`.** RFC 9110 section 10.1.5 defines `User-Agent` as the user-agent software identity, says it is used for interoperability reports and analytics, and says a user agent SHOULD send it on each request unless configured not to. This is the only standard header that directly matches "what product is making this HTTP request."
- **`Referer` is standard, but OpenRouter's `HTTP-Referer` is not the standard field.** RFC 9110 section 10.1.3 defines `Referer` as the URI from which the target URI was obtained and spends significant text on privacy restrictions. OpenRouter instead asks for `HTTP-Referer`, using it as an app URL identifier. That name and meaning are OpenRouter-specific even though it resembles the CGI environment variable form of the standard `Referer` header.
- **`From` is standard but not suitable as a mandatory default.** RFC 9110 section 10.1.2 defines `From` as an email address for the human responsible for a user agent. Robotic agents SHOULD send it so servers can contact an operator, but non-robotic agents should not send it without explicit user configuration because of privacy and security policy concerns. The harness can support an operator contact later, but must not invent one or require it globally.

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@@ -22,7 +22,7 @@ Web access is a first-class capability seam following [the capability-seam RFC](
Providers do not register tools. Providers register capabilities. `dsh-tool-web` is the only owner of model-facing names, descriptions, prompt guidance, JSON schemas, and presentation.
Search and fetch are separate capabilities and separate model-facing tools, but they are deliberately one seam. `ctx.web` is a single web-access middle layer between provider packages on one side and the tool consumer on the other: one service to inject, one provider-selection policy owner, one abort/error vocabulary, one place a product configures "how this harness reaches the web." The two halves do not share a request schema and have no shared business logic — search normalizes provider-backed discovery into a portable result with optional answer text and citeable sources, while fetch retrieves a concrete public HTTP(S) URL and returns a status code plus bounded decoded content — but they are parallel registries on one capability surface, not two surfaces. The cost is a `WebService` whose registry/exec methods come in `Search`/`Fetch` pairs; that parallelism is intentional, not a missed extraction. Splitting into `dsh-search` and `dsh-fetch` is the rejected alternative below.
Search and fetch are separate tools but one web-access seam. `ctx.web` owns provider selection, abort/error vocabulary, and deployment configuration for both parallel registries. Their request schemas and provider logic remain separate; the shared service is the product boundary for reaching the web.
`dsh-tool-web` registers model-facing web tools when the product has enabled those tools and the `ctx.web` seam is present. Backend availability is an execution-time concern, not a schema-registration concern:
@@ -64,9 +64,9 @@ flowchart LR
toolWeb -->|ctx.tools.register| webFetch["tool: web_fetch"]
```
`@deepseek-ai/dsh-web` depends only on Cordis and low-level harness support. It declares `ctx.web`, provider interfaces, request/result types, the provider status type, and error codes. It does not import tool, agent, session, LLM, or provider packages.
`@deepseek-ai/dsh-web` depends only on Cordis and low-level harness support. It declares `ctx.web`, provider interfaces, request/result types, the provider availability contract, and error codes. It does not import tool, agent, session, LLM, or provider packages.
Provider packages depend on `@deepseek-ai/dsh-web` and Cordis. They own credentials, endpoint config, provider-specific request mapping, provider-specific response parsing, and provider-specific error translation into `WebError`. They issue network requests with the platform-native `fetch` (Node 24), mirroring `@deepseek-ai/dsh-llm-deepseek`'s adapter, NOT a cordis HTTP-client service (`ctx.http`/`@cordisjs/plugin-http`) — even where a Perplexity provider's request is shaped like an OpenAI-compatible chat completion, that wire shape is a provider-private detail and does not make the provider depend on `ctx.llm`. A provider does NOT own the `ctx.web` key (two search providers cannot both own it): like `dsh-llm-deepseek`, each provider package is a function/namespace plugin (`inject: ['web']`) whose `apply` constructs the backend and calls `ctx.web.registerSearchProvider` / `registerFetchProvider`. `@deepseek-ai/dsh-web` is the `export default` service that owns the key.
Provider packages depend only on `dsh-web` and Cordis. They own credentials, endpoints, wire mapping, parsing, and `WebError` translation, using platform `fetch`. Each provider injects the shared service and registers a backend; only `dsh-web` owns the `ctx.web` key. Provider-private protocol shapes do not create dependencies on `ctx.llm` or a Cordis HTTP service.
`@deepseek-ai/dsh-tool-web` depends on `@deepseek-ai/dsh-web`, `@deepseek-ai/dsh-tools`, `@deepseek-ai/dsh-system-prompt`, and Cordis. It never imports concrete provider packages.
@@ -77,52 +77,42 @@ Provider packages depend on `@deepseek-ai/dsh-web` and Cordis. They own credenti
```ts
interface WebSearchProvider {
readonly id: string
status(): WebProviderStatus
search(request: WebSearchRequest, exec?: WebExecContext): Promise<WebSearchResult>
available(): boolean
search(request: WebSearchRequest, signal?: AbortSignal): Promise<WebSearchResult>
}
interface WebFetchProvider {
readonly id: string
status(): WebProviderStatus
fetch(request: WebFetchRequest, exec?: WebExecContext): Promise<WebFetchResult>
available(): boolean
fetch(request: WebFetchRequest, signal?: AbortSignal): Promise<WebFetchResult>
}
interface WebService {
registerSearchProvider(provider: WebSearchProvider): () => void
registerFetchProvider(provider: WebFetchProvider): () => void
search(request: WebSearchRequest, exec?: WebExecContext): Promise<WebSearchResult>
fetch(request: WebFetchRequest, exec?: WebExecContext): Promise<WebFetchResult>
}
interface WebExecContext {
readonly signal?: AbortSignal
search(request: WebSearchRequest, signal?: AbortSignal): Promise<WebSearchResult>
fetch(request: WebFetchRequest, signal?: AbortSignal): Promise<WebFetchResult>
}
```
`WebExecContext` is execution control, not business input. It carries only `signal`, so `tool-web` propagates turn cancellation, tool timeout, and agent disposal into provider network requests, SSE readers, and expensive decoding. It does not pass `ToolExecution` through the seam — that would make `dsh-web` depend on `dsh-tools`.
The optional signal is execution control, not business input: `tool-web` passes `exec.signal` directly so turn cancellation, tool timeout, and agent disposal reach provider network requests, stream readers, and expensive decoding. The seam does not pass `ToolExecution` through — that would make `dsh-web` depend on `dsh-tools`.
Provider ids are stable strings and unique within their capability kind. Registering a duplicate search provider id or duplicate fetch provider id fails rather than silently replacing the old provider. Provider registration returns a disposer and follows the existing `ctx.tools.register()` / `ctx.systemPrompt.section()` pattern: the mutation is wrapped in `ctx.effect()` so the registration is torn down with the contributing fiber.
## Provider status and selection
## Provider availability and selection
Provider status and capability selection are separate concepts, but both stay minimal. A provider reports only whether that concrete implementation is usable by cheap local checks such as credential presence or parseable endpoint config. A provider `status()` must not make network calls.
Provider availability and capability selection are separate concepts, but both stay minimal. A provider reports only whether that concrete implementation is usable by cheap local checks such as credential presence or parseable endpoint config. A provider `available()` must not make network calls.
`LlmService` has no status type at all: availability is expressed as registry membership plus a resolution-time throw. `ctx.web` follows the same discipline. The seam exposes no aggregated capability-status query — `search()` / `fetch()` derive the selection on each call from the configured provider id, the registered providers, and each provider's cheap local `status()`, and a selection failure is the structured `WebError` thrown at execution time, whose code answers "in which broad category does this capability fail" and whose message answers "exactly which provider/ids/reason." A caller that needs to know whether a capability can run executes and routes that error; nothing is stored as mutable service state.
`LlmService` has no status type at all: availability is expressed as registry membership plus a resolution-time throw. `ctx.web` follows the same discipline. The seam exposes no aggregated capability-status query — `search()` / `fetch()` derive the selection on each call from the configured provider id, the registered providers, and each provider's cheap local `available()` boolean, and a selection failure is the structured `WebError` thrown at execution time. A caller that needs to know whether a capability can run executes and routes that error; nothing is stored as mutable service state.
`WebProviderStatus` is an input to selection, not a health system. `tool-web` never calls a provider's `status()` directly — its only path into the seam is `search()` / `fetch()` — so selection policy has one owner.
```ts
type WebProviderStatus =
| { readonly available: true }
| { readonly available: false; readonly reason: 'missing-credential' | 'misconfigured' }
```
The boolean is an input to selection, not a health system. `tool-web` never calls a provider's `available()` directly — its only path into the seam is `search()` / `fetch()` — so selection policy has one owner.
Selection must not depend on registration order. Cordis load order, config ordering, and HMR timing are not product semantics.
| Situation | Execution behavior |
|---|---|
| A configured provider id is registered and `status().available === true` | runs that provider |
| A configured provider id is registered and `available() === true` | runs that provider |
| A configured provider id is not registered | fails with `WEB_PROVIDER_CONFIGURED_MISSING` |
| A configured provider id is registered but unavailable | fails with `WEB_PROVIDER_CONFIGURED_UNAVAILABLE` |
| No provider id is configured and exactly one provider for that kind is registered and available | runs that single provider |
@@ -184,8 +174,6 @@ interface WebSearchRequest {
}
interface WebSearchResult {
readonly providerId: string
readonly query: string
readonly content?: string
readonly sources: readonly WebSearchSource[]
readonly truncated: boolean
@@ -212,20 +200,17 @@ The `web_fetch` implementation is an anonymous public HTTP(S) fetch provider, `l
The seam request stays smaller than OpenCode's model-facing tool:
- `url`: required HTTP(S) URL.
- `timeoutMs`: optional positive number capped by the provider.
The seam request deliberately does not include `format`, `prompt`, or provider-specific extraction controls. `format` is a presentation decision over a fetched resource; `prompt` is a higher-level LLM summarization instruction; extraction APIs such as Firecrawl, Exa, Tavily, or Parallel may not expose a concrete HTTP response. If the product later needs provider-backed page extraction, that is a separate `web_extract` capability or a deliberate widening of this seam — extract semantics are never smuggled into `web_fetch` by making every HTTP field optional.
The seam request deliberately does not include a per-call timeout, `format`, `prompt`, or provider-specific extraction controls. Cancellation is the direct optional execution signal, while the fetch provider owns one deployment-configured timeout backstop. `format` is a presentation decision over a fetched resource; `prompt` is a higher-level LLM summarization instruction; extraction APIs such as Firecrawl, Exa, Tavily, or Parallel may not expose a concrete HTTP response. If the product later needs provider-backed page extraction, that is a separate `web_extract` capability or a deliberate widening of this seam — extract semantics are never smuggled into `web_fetch` by making every HTTP field optional.
HTTP status is part of the fetched resource state, not automatically a tool failure. A successful network fetch of a `404` or `500` response returns `WebFetchResult` with the status code and a bounded decoded body when the content type is supported. `WebError` is for failures to safely retrieve or represent the resource: invalid or blocked URL, redirect policy violation, timeout, abort, response too large, unsupported content type, provider failure, or network failure.
```ts
interface WebFetchRequest {
readonly url: string
readonly timeoutMs?: number
}
interface WebFetchResult {
readonly providerId: string
readonly url: string
readonly statusCode: number
readonly body: WebFetchBody
@@ -239,7 +224,7 @@ type WebFetchBody =
`WebFetchResult.url` is the final URL after allowed redirects. The request URL is already present in `WebFetchRequest`, so there is no separate `requestedUrl`/`finalUrl` pair.
`WebFetchBody` is a CLOSED discriminated union owned by `dsh-web`, not a merge-extensible map. The merge-extensible pattern (`ContentBlockMap`) exists for variants that independent plugins introduce and the seam cannot foresee; body kinds are not that — `dsh-web` declares the kind, the fetch provider decodes it, and `dsh-tool-web` renders it, so a new kind is a coordinated change across three known packages, not a plugin extension. Keeping it closed buys compile-time exhaustiveness: consumers `switch` on `kind` ending in `default: assertNever(body, …)`, so adding a kind breaks compilation at every consumer that must render it (e.g. `tool-web`'s `html`→markdown vs `text` passthrough) until that arm is written. Each arm stays its own object literal even when the fields coincide today, leaving room for arm-specific fields (a future `pdf` body's `pageCount`, a `json` body's parsed value) without reshaping the type. Since the harness is unreleased, extending this closed union later is free (no migration, no compat shim).
`WebFetchBody` is a closed discriminated union because body kinds require coordinated changes to the seam, provider, and tool rather than independent plugin extension. Exhaustive switches make a new kind fail compilation at every renderer until handled. Separate object arms leave room for kind-specific fields.
The provider owns safe resource retrieval: URL validation, HTTP transport, redirect policy, timeout, abort propagation, byte caps, charset decoding, content-type classification, and binary rejection. `dsh-tool-web` owns presentation: HTML-to-markdown, HTML-to-text, truncation formatting for the model, and future summaries.
@@ -257,11 +242,11 @@ SSRF / private-network protection (blocking private, loopback, link-local, multi
`dsh-tool-web` owns two `ToolDefinition`s: `web_search` and `web_fetch`. It owns model-facing JSON schemas, snake_case argument names, prompt sections, result rendering to `ContentBlock[]`, `presentCall`, and `presentResult`.
`dsh-tool-web` must not enumerate providers or call provider `status()` directly. Its only path into the seam is `ctx.web.search()` / `ctx.web.fetch()`. That keeps provider selection in one layer; otherwise the tool package could decide one provider is usable while execution resolves a different state.
`dsh-tool-web` must not enumerate providers or call provider `available()` directly. Its only path into the seam is `ctx.web.search()` / `ctx.web.fetch()`. That keeps provider selection in one layer; otherwise the tool package could decide one provider is usable while execution resolves a different state.
Tool registration is a minimal stable sync: on plugin startup the `dsh-tool-web` `Config` (`search?: boolean`, `fetch?: boolean`, both default `true`) enables or disables each web tool; an enabled tool is registered with a fiber-scoped disposer via the effect-based registry; neither tool is disposed merely because its selected provider is missing, unusable, or ambiguous; disposing the `tool-web` fiber tears down its registrations automatically.
Provider status changes affect execution results and diagnostics, not whether the model-facing schema exists. If a product wants no web tools at all, it disables `dsh-tool-web` or the individual web tool in config; if it wants web tools but the backend is misconfigured, the model sees a structured tool error at execution time.
Provider availability changes affect execution results and diagnostics, not whether the model-facing schema exists. If a product wants no web tools at all, it disables `dsh-tool-web` or the individual web tool in config; if it wants web tools but the backend is misconfigured, the model sees a structured tool error at execution time.
The prompt guidance explains the semantic split — `web_search` for discovery and current information, `web_fetch` when the model needs the content of a specific URL — and the prompt and tool result tell the model to cite relevant URLs with markdown links.

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@@ -29,7 +29,7 @@ provider seam dsh-fs ctx.fs: text IO + ATOMIC mutation primitives who
provider dsh-fs-local local implementation of ctx.fs
```
The model is **additive, not subtractive**: `ctx.fs` on its own is a complete, unconstrained text-storage seam — `read` reads, `write` unconditionally creates-or-overwrites, `edit` unconditionally replaces literal text in the current content. There is no "先读后写", no version check, nothing to remove; the bare provider just does the I/O atomically. `dsh-fs-policy` is a plugin that *adds* constraints on top: observed-state, read-before-edit, and "write/edit must be based on the version you read". So removing `dsh-fs-policy` does not break `dsh-tool-fs` at the service-injection boundary; it removes the policy gate and leaves the bare provider behavior. The intended deployment stance is that a config loading the fs tools also loads `dsh-fs-policy`, so the user-facing behavior and prompt discipline are read-before-write/edit (the `coding-agent` and `acp-agent` demos wire the full stack). The bare-provider mode exists because the tool should not be method-coupled to the policy plugin, not because an unconstrained filesystem is the normal product stance.
The model is additive: bare `ctx.fs` performs atomic, unconstrained text I/O, while `dsh-fs-policy` adds observed state, read-before-edit, and version guards. Removing the policy therefore leaves the tools usable but unconstrained. Shipped agent configs load the policy; the bare mode exists to keep policy optional at the service boundary, not as the normal deployment stance.
`dsh-tool-fs` no longer injects `fileContext`. It injects `fs` and `tools`/`systemPrompt`.
@@ -68,9 +68,7 @@ The events live in `@deepseek-ai/dsh-fs`, not in `dsh-fs-policy`. This is forced
These events carry existing `dsh-fs` vocabulary (`FsTarget`, `FsVersion`, `FsWriteIntent`) plus an opaque actor — not model-facing concepts (no line windows, numbered lines, or rendered footers leak down).
**The two `fs/*` decision events are single-slot decision points, NOT a composable interception chain.** A waterfall listener that does not call `next()` short-circuits the rest of the chain (verified in [vendor/cordis/src/events.ts](../../../../vendor/cordis/src/events.ts) — `waterfall` runs listeners around the final `next` thunk, and a listener that returns without calling `next()` reaches neither later listeners nor the tool's default thunk). `dsh-fs-policy` fully decides the write/edit expectation and does not call `next()`, so it occupies that one decision slot in the default deployment. This is deliberate: "what version basis does this mutation guard against" is a single decision, not an accumulation. The names (`fs/write-intent`, `fs/edit-intent`) say "produce the value", not "authorize", so they do not imply a stackable authorization chain. Genuinely composable interception (permission, audit, sandbox) belongs on the existing `tools/execute` waterfall, which every tool call already flows through — not on this fs version-decision slot.
**The occupant is decided by registration order — first-registered (or `prepend`ed) wins.** cordis dispatches waterfall listeners in registration order (`push`, or `unshift` for `prepend` — [vendor/cordis/src/events.ts](../../../../vendor/cordis/src/events.ts)), and the first non-`next()` decider short-circuits the rest. So the slot is **first-wins**, and `dsh-fs-policy` owning it rests on the default deployment convention: it is the decider registered for these events. The event shape does NOT itself guarantee "an unread edit is rejected" — a plugin that registers a looser `fs/edit-intent` decider BEFORE `dsh-fs-policy` (or with `prepend`) would decide first and bypass the `FS_NOT_OBSERVED` gate. That is the inherent property of a first-wins single slot, stated here so it is not mistaken for an enforced invariant. This RFC does not add a multi-policy composition mechanism; the implementation requirement is that `dsh-tool-fs` dispatches these waterfalls on every write/edit path and that a config wiring the fs tools loads `dsh-fs-policy` as the policy decider.
**The two `fs/*` decision events are single-slot, first-wins waterfalls.** `dsh-fs-policy` returns without calling `next()`, so it owns the slot in the default deployment; a listener registered earlier or with `prepend` would replace that policy. Permission, audit, and sandbox concerns remain on the composable `tools/execute` waterfall.
The actor is typed `object` in `dsh-fs` — a pure opaque carrier the provider seam never reads or narrows. The owner-derivation (`actor.agent?.session`) and the `{ agent?: { session? } }` structural shape stay entirely inside `dsh-fs-policy`, which narrows the `object` actor to that shape in its listeners. `dsh-fs` owns the event names and the fs vocabulary; it does NOT own the policy layer's runtime owner structure.
@@ -124,7 +122,7 @@ The tool keeps its model-facing schemas (`read`/`write`/`edit`, byte-for-byte un
The tool passes `exec` (the tool-execution context) as the `actor` argument on every dispatch, so `dsh-fs-policy` can derive its observed-state owner. The tool does not know whether the policy plugin is present: it always provides the bare default behavior in the `next` thunk, and `dsh-fs-policy` short-circuits the thunk before it runs in the default deployment.
**`fs/observed` fires AFTER the mutation already succeeded**, via a plain `ctx.emit`. The event contract is intentionally narrow: an `fs/observed` listener MUST be synchronous and side-effect-only — `dsh-fs-policy`'s listener is a `WeakMap.set`, which cannot throw under normal operation and returns no promise. The tool does not guard the emit, so a listener that violates the contract by throwing would surface as the tool's `isError` result ([tools/index.ts](../../../../packages/core/tools/src/index.ts) — `ToolRegistry.execute` catches a tool throw into an error result) — reporting failure for a write/edit that actually happened. That is the price of keeping the event a plain fire-and-forget recorder: cordis `emit` does not await listener promises, so async or fallible audit/telemetry/listener work does not belong on this event. If layered or async observation is ever wanted, that is a new event with its own dispatch story.
**`fs/observed` fires after a successful operation.** Its listeners must be synchronous, non-throwing recorders; the tool does not guard the plain emit, so a throwing listener would report failure after a mutation already succeeded. Async or fallible observation needs a separate event contract.
## Policy plugin contract (`dsh-fs-policy`)
@@ -154,7 +152,7 @@ This amends — does not reverse — [the split-fs-seam RFC](../simplification/2
## Verification
The decoupling and its semantics are pinned by tests: a bare-provider config (no `dsh-fs-policy`) boots the `dsh-tool-fs` root plugin and `read`/`write` (create and overwrite)/`edit` work against the real `dsh-fs-local` an unread edit and an unread overwrite both succeed, proving the tool carries no `fileContext` dependency, while the same operations with `dsh-fs-policy` present are rejected `FS_NOT_OBSERVED` / gated `createIfAbsent`. A second `fs/edit-intent` listener registered after `dsh-fs-policy` is asserted NOT reached (first-wins short-circuit). A stale-read edit reports `FS_STALE_VERSION` through provider CAS, with `dsh-fs-policy` performing no `stat`; the tool's `stat` budget (read = 1, write = 0, edit = 0, on both paths) is asserted directly. Model-facing schemas stayed byte-for-byte unchanged, so snapshot transcript goldens are unaffected.
Tests pin both paths: without `dsh-fs-policy`, the root tool plugin boots against `dsh-fs-local`, and read, create, overwrite, and unread edit succeed; with the policy, unread edit returns `FS_NOT_OBSERVED` and unread overwrite is gated by `createIfAbsent`. A later intent listener is not reached after the policy decides. Stale edits fail through provider CAS while the policy performs no `stat`; the tool budgets remain one `stat` for read and zero for write or edit on either path. Model-facing schemas remain byte-for-byte unchanged, so snapshots do not change.
## Alternatives considered

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@@ -6,7 +6,7 @@ Status: implemented
The hooks subsystem runs external hook commands the way Claude Code and Codex do: a hook is a shell command that receives its event payload as **JSON on stdin** and reads context from a handful of **environment variables** (`CLAUDE_PROJECT_DIR`, `CLAUDE_PLUGIN_ROOT`, `PLUGIN_ROOT`, …). The harness already has a perfectly good command runner behind the `ctx.bash` capability seam ([dsh-bash](../../../../packages/bash/bash) → [dsh-bash-local](../../../../packages/bash/bash-local)), with process-group kills, output truncation/spill, and a credential scrub. Reusing it for hook execution means a hook bridge does not re-implement subprocess plumbing — but the seam had no way to write stdin or set extra env. This RFC adds those two inputs.
**These fields are NOT a new security boundary.** It is tempting to frame arbitrary-stdin / arbitrary-env as "dangerous, so gate who may use them" — but that framing is wrong, because a model driving the `bash` tool **already** has equivalent power through ordinary shell syntax: `FOO=bar cmd` sets an env var, a heredoc or `printf … | cmd` feeds arbitrary stdin. Adding `env`/`stdin` as seam fields grants the model no capability it lacks. In particular they cannot exfiltrate the harness's ambient credentials: the real control for that is the **credential scrub** in [dsh-bash-local](../../../../packages/bash/bash-local)'s `childEnv()`, which strips `*KEY*`/`*SECRET*`/`*TOKEN*` from `process.env` before the child sees it (see [docs/defensive-patterns.md](../../../defensive-patterns.md) § "Never hand untrusted output the ambient environment or predictable paths"). The scrub works regardless of these fields — a model cannot read a value that is not in the environment, and tool-call arguments are static JSON, never shell-evaluated, so a model cannot write `env: {LEAK: $DEEPSEEK_API_KEY}` and have it expand. So the security question is already answered by the scrub; this RFC is only about giving trusted in-process callers a clean way to pass a JSON payload + `CLAUDE_*` vars without routing them through model-visible shell text.
`stdin` and `env` do not create a new model capability because ordinary shell syntax already supplies both. Ambient credentials are protected by `dsh-bash-local`'s child-environment scrub, not by hiding these seam fields; model tool arguments are static JSON and do not expand shell variables. The fields therefore serve trusted in-process callers, such as hook bridges, that need to pass structured input and `CLAUDE_*` variables without embedding them in model-visible shell text. See [defensive-patterns.md](../../../defensive-patterns.md) for the ambient-environment rule.
## Decision
@@ -14,18 +14,18 @@ Add `stdin?: string` and `env?: Record<string, string>` to **both** `BashExecReq
Three deliberate choices:
1. **The model-facing `bash` tool simply does NOT expose `stdin`/`env` as parameters** — not as a security wall, but because bash syntax already covers the model's needs, so duplicating them as tool params would be redundant surface. [dsh-tool-bash](../../../../packages/bash/tool-bash)'s `bash` tool builds its `BashExecRequest` from `command`/`workdir`/`timeoutMs`/`signal`/`owner` only; a model that includes `env`/`stdin` keys in its tool-call arguments simply has them ignored. A regression guard (`tool-bash` "does not forward env/stdin" tests) drives the real tool with those extra args and asserts the recorded request carries neither field — its purpose is to catch a future refactor that blindly spreads `...args` into the request and silently starts forwarding model input into the post-scrub `env` merge, NOT to defend a trust boundary. In-process plugins (the hooks bridges, native plugins) that construct a `BashExecRequest` directly set the fields; the seam imposes no access policy (consistent with how `owner` works — the executor stores but never interprets it).
1. **The model-facing tool omits `stdin` and `env`.** Shell syntax already covers those needs, so duplicate parameters would add surface without authority separation. The tool builds requests only from declared model arguments, signal, and owner; trusted in-process callers may set the seam fields directly. Harness-owned variables use the separate `dshEnv` channel from the [managed environment decision](../feature/2026-07-10-agent-session-identity-and-log-location.md), so ordinary `env` cannot replace them.
2. **`env` merges AFTER the credential scrub, so an explicit caller entry always wins** — even a credential-shaped name. This is correct because the scrub's job is narrow: stop the harness's *ambient* `process.env` credentials from leaking into a spawned command. A caller that explicitly sets a var has named a value it already holds (not the ambient secret), so the scrub is not a constraint on it. `childEnv(extra?)` layers `scrub(process.env)``ENV_OVERRIDES` (the model-friendly `TERM=dumb` etc.) → `extra`, last-wins.
2. **`env` merges AFTER the credential scrub, so an explicit caller entry wins even on a credential-shaped name.** The later managed-namespace decision reserves `DSH_*`: ambient entries are removed, ordinary `env` cannot set them, and trusted `dshEnv` merges last. The complete order is `scrub(process.env, including DSH_*)``ENV_OVERRIDES` → ordinary `env``dshEnv`.
3. **`stdin`/`env` are required-absent-OK (plain optional) on the resolved spec, NOT required-but-nullable like `owner`.** `owner` is required-but-nullable because a *silently* missing owner yields an unowned, cross-session-readable task — a security footgun that a visible `undefined` guards against. `stdin`/`env` have no such hazard: a missing one means "no stdin / no extra env", which is the safe, ordinary case (every model-driven call). So they stay plain optionals, matching `signal`.
`dsh-bash-local` spawns stdin as a `'pipe'` (writing the supplied bytes, then closing) ONLY when a caller set `stdin`; with none supplied it uses `'ignore'` — fd 0 → `/dev/null` — the exact pre-seam default. This distinction is observable and deliberate: a closed empty pipe and `/dev/null` are NOT the same file type (node's spawn pipe is an `AF_UNIX` socket, so `test -c /dev/stdin` holds for `/dev/null` but not for an empty pipe), so the no-stdin path — every model-driven call — must keep `/dev/null` rather than regress to an always-open pipe. Each branch's `stdio` tuple is a literal, which preserves the typed `spawn` overload that guarantees non-null `stdout`/`stderr`. When stdin IS written, a child that exits without reading makes the write fail EPIPE; that error is swallowed (the command's outcome rides on its exit code/output, not the write) so it never crashes the host or rejects `done`.
`dsh-bash-local` creates a stdin pipe only when bytes are supplied; otherwise fd 0 remains `/dev/null`, preserving prior behavior. It writes the bytes and closes the pipe. `EPIPE` from a child that exits without reading is ignored because command exit and output determine the result.
## Alternatives considered
An earlier sketch of this work also proposed making `SENSITIVE_ENV_PATTERN` configurable. Validating against the code, that is **speculative and already subsumed**: `run.ts` documents a configurable whitelist as future work, and the new explicit `env` field — merged after the scrub — already gives a caller full control, including over credential-shaped vars. There is no current caller that needs to *broaden* the ambient scrub (the hazard runs the other way). Adding a config knob now would be a speculative surface with no consumer. If a real workflow ever needs to forward a specific ambient credential, the explicit `env` field is the supported path; a configurable scrub can be reconsidered then.
**Configurable ambient-secret scrub.** Rejected as speculative. Trusted callers can explicitly provide required values after the scrub without weakening the default ambient protection.
## Consequences
A hook bridge builds a `BashExecRequest` with the hook's JSON payload as `stdin` and its `CLAUDE_*`/`PLUGIN_ROOT` vars as `env`, and runs it through the same `ctx.bash` everything else uses — no bespoke subprocess code, and the full process-group-kill / truncation / spill machinery for free. The model-facing attack surface is unchanged (the credential scrub, not these fields, is what bounds it), and the `bash` tool's request-building stays the single place that decides which fields a model call carries — guarded by a test that fails if a refactor starts forwarding model input. The vocabulary addition is documented in [docs/core-data-structures/bash.md](../../../core-data-structures/bash.md) (the `type-equiv` request/spec blocks) and the three bash-package READMEs.
Hook bridges pass JSON payloads and hook-specific variables through the existing bash seam, retaining its process-group, truncation, and spill behavior. The model surface remains unchanged, and the bash tool remains the sole owner of model-call request construction. The vocabulary lives in [the bash data-structure reference](../../../core-data-structures/bash.md).

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@@ -12,7 +12,7 @@ The harness extends the agent loop through a Cordis event taxonomy (see [the mic
Two problems motivated pinning the semantics down. First, several turn/step boundaries existed BOTH as a durable `SessionEvent` (`turn/start`, `turn/end`, `step/start`, `step/end`) AND as a mirrored `agent/*` emit (`agent/turn-start`, `agent/turn-end`, `agent/step-start`, `agent/step-end`). A consumer had two sources of truth for the same fact, and every lifecycle change had to update both. Second, the upcoming Hooks subsystem needs ONE coherent, documented surface to subscribe to — a plugin author (and the Claude Code / Codex hook bridges built on top) must know, without reading the loop, whether to listen on a session event or an agent event, and why.
This is the foundational change in a stack that adds a Hooks subsystem; it establishes the vocabulary the later PRs (interception-Decision reshape, the `hook/*` durable log, the bridges) build on.
This vocabulary is the foundation for interception decisions, the durable `hook/*` log, and the Claude Code and Codex bridges.
## Decision
@@ -28,9 +28,9 @@ This is the foundational change in a stack that adds a Hooks subsystem; it estab
## Consequences
- The loop no longer emits any boundary mirror; `closeStep` appends `step/end` only and `closeTurn` appends `turn/end` only. A throwing `step/end`/`turn/end` session-event listener is the surviving boundary-listener failure path (contained inside `closeStep`/`closeTurn``Session.append` pushes the event before notifying listeners, so the boundary is durable and the turn closes balanced regardless).
- The loop no longer emits any boundary mirror; `closeStep` appends `step/end` only and `closeTurn` appends `turn/end` only. `Session.append` owns post-commit observer containment, so a throwing boundary observer cannot change the turn outcome or starve later consumers; an acceptance or internal validation failure still escapes before the boundary enters the log.
- Tests that observed boundaries via the removed emits now observe the durable `turn/start`/`turn/end`/`step/start`/`step/end` session events — the behavior they pin (boundary ordering, step counting) is unchanged; only the feed they read moved to the canonical one. The tests that exercised a *throwing turn-boundary emit listener* were deleted, because that code path no longer exists (there is no emit to throw from). Per [AGENTS.md "tests document behavior, not golden truth"](../../../../AGENTS.md), the behavior and its test moved (or died) together.
- The loop marks the step open (`stepOpen = true`) BEFORE appending `step/start`, because `Session.append` pushes the event to the log before notifying `session/event` listeners (validation throws happen earlier, before the push — see [the session append contract](../../../core-data-structures/session.md)). So a throwing `step/start` session-event listener runs with the step already open and the event already in the log: the loop's outer catch then calls `closeStep()`, which appends the balancing `step/end`, and the turn closes balanced with an error (`turn/start → step/start → step/end → turn/end` — verified by the invariants oracle in the regression test). Closing the open step is owed precisely because the marker is set first.
- The loop marks the step open (`stepOpen = true`) only after `append('step/start')` returns. Internal dispatch validation runs before the log push and may reject without opening a step; post-commit `session/event` observer failures are contained inside `Session.append`. The marker therefore represents exactly the committed boundary that owes a later `step/end`.
- The full realization of this is [the simplification RFC "Stop mirroring durable boundaries as agent events"](../simplification/2026-06-20-remove-agent-boundary-mirror-events.md): all four boundary mirrors are removed and every consumer reads boundaries off `session/event`. `agent/steering` (not a boundary mirror) stayed outside that RFC's scope and was removed by its own follow-up, [Remove the `agent/steering` mirror emit](../simplification/2026-07-04-remove-agent-steering-mirror.md) — it mirrored the durable `steering/message`.
- The cordis events catalog (`docs/cordis-catalog/events.md`) is regenerated to drop the mirror events.

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@@ -6,13 +6,13 @@ Status: implemented
The ACP bridge gives every session its own workspace: `session/new` records the editor's project directory as `SessionHeader.cwd`, and `dsh-tool-bash` defaults each bash call's `workdir` to the calling agent's `session.header.cwd` (see [the per-session cwd RFC work in `packages/ui/acp`](../../../../packages/ui/acp) and `resolveWorkdir` in `dsh-tool-bash`). So a bash command in session A runs in A's project, and in session B runs in B's — one server process, N workspaces.
The filesystem tools did NOT honor this. `ctx.fs.resolve(path)` took no caller context, and `dsh-fs-local` resolved every relative path against a single `config.cwd` fixed at plugin load (`process.cwd()`). In the ACP demo that means `write foo.txt` and `bash cat foo.txt` resolve `foo.txt` against **different** directories — the fs tools against the server's launch dir, bash against the session's project dir. The two tools disagree about what "the current directory" is, which is a correctness bug the moment an editor opens any project other than the server's launch dir. It only appeared to work in the snapshot harness because that harness launches the child process in the same temp dir it passes as the session cwd, so the two coincide.
Filesystem resolution used one plugin-load cwd while bash used the session project directory. Relative paths therefore disagreed whenever the editor project differed from the server launch directory; snapshots hid the bug by making those paths identical.
## Decision
Thread the caller's session cwd into path resolution, exactly as `dsh-tool-bash` already does for `workdir`. The **caller** (the tool) supplies the cwd; the provider does not read a session or agent.
- `FileSystem.resolve` widens to `resolve(path: string, opts?: { cwd?: string }): Promise<FsTarget>`. `opts.cwd` is the base a RELATIVE `path` resolves against; an absolute `path` ignores it; omitting `opts.cwd` uses the backend's own default. An options object (not a positional `cwd?`) leaves room for future resolution hints without another signature change.
- `FileSystem.resolve` accepts `resolve(path: string, opts?: { cwd?: string; signal?: AbortSignal }): Promise<FsTarget>`. `opts.cwd` is the base a RELATIVE `path` resolves against; an absolute `path` ignores it; omitting `opts.cwd` uses the backend's own default. `opts.signal` cancels resolution when the backend performs I/O. The options object keeps both caller-owned resolution controls together without positional growth.
- `dsh-fs-local.resolve` uses `resolveLocalTarget(opts?.cwd ?? this.config.cwd, path)`. `config.cwd` stays the default for a caller that supplies none (non-ACP / no-session use, and the single-session stdio demo where `process.cwd()` IS the workspace).
- `dsh-tool-fs`'s `read`/`write`/`edit` derive the session cwd through a shared `sessionCwd(exec)` helper (`exec.agent?.session.header.cwd`, mirroring bash's `resolveWorkdir`) and pass it to `resolve`. A non-agent / headerless caller yields `undefined`, so the backend applies its default.

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@@ -22,7 +22,7 @@ Add a **persisted, tool-private presentation channel** so a tool's `execute` can
type ToolExecuteReturn = ContentBlock[] | { content: ContentBlock[]; meta?: unknown }
```
`meta` is an opaque payload the core never interprets — typed `unknown` at every seam (the tool that produced it owns and narrows its shape). It MUST be JSON-serializable: the registry threads it onto the `tool/result` **session event**, and `Session.append` runtime-validates all event data with the existing `isJsonValue` predicate, so a non-serializable `meta` is rejected at the source. On replay the same `meta` is read back and handed to `presentResult` via a widened `ToolResult` (`{ content, isError, meta? }`). Because the payload lives in the event log, the diff reproduces on session reload / snapshot replay **for free** — the event-sourcing guarantee, not a re-computation. Typing `meta` as `unknown` (rather than a shared serializable-value type) keeps the tools core free of a dependency it would otherwise take just to name the type, and the runtime `isJsonValue` gate — not the static type — is what actually enforces serializability.
`meta` is tool-owned `unknown` that the core persists without interpretation. `Session.append` rejects non-JSON values, and replay passes the stored payload back to `presentResult`; presentations therefore reproduce without I/O or recomputation. Runtime validation avoids adding a shared serializable-value dependency to the tools core.
This is the general shape ("a tool attaches durable result presentation"), not an fs-specific one — any tool can use it.
@@ -31,7 +31,7 @@ This is the general shape ("a tool attaches durable result presentation"), not a
Per the [capability-seam split](2026-06-13-capability-seams.md), the storage backend returns only **storage facts** and the model-facing tool owns **presentation**:
- `dsh-fs` widens `FsEditOutcome` with `{ before: string; after: string }` and `FsWriteOutcome` with `{ before: string | null; after: string }` (`before: null` ⇒ a create, or an existing-but-undiffable binary/non-UTF-8 file). The local backend already holds both texts at write time; it returns them as raw LF-normalized text, with **no diff/UI concept** entering the seam.
- `dsh-tool-fs` computes the contextual hunk from before/after and attaches it as `meta: { diffs: FileDiff[] }`. A contextual hunk is computed only when a before-version exists — edit always; write on overwrite; a create has no before, matching `claude-agent-acp`'s empty `structuredPatch` on create. But the completed `tool_call_update` is ALWAYS a `diff` card for a successful mutation: an ACP `tool_call_update.content` REPLACES the call's content, so rendering the model-facing result text would clobber the pending diff. So `write`'s result falls back to an args-derived whole-file diff (`oldText: null`) when it has no contextual hunk (a create, or an overwrite whose content is unchanged), and `edit` — which always changes content — always has a hunk. A failed/aborted/policy-rejected mutation applied nothing, so it carries no `meta` and falls through to the generic error rendering (its message must show).
- `dsh-tool-fs` stores contextual hunks in `meta: { diffs: FileDiff[] }`. Successful mutations always complete with a diff card because ACP result content replaces the pending card: creates or unchanged overwrites fall back to an args-derived whole-file diff, while edits use applied hunks. Failed mutations carry no diff metadata and render their error normally.
### 3. The bridge renders a `diff` result card
@@ -39,7 +39,7 @@ Per the [capability-seam split](2026-06-13-capability-seams.md), the storage bac
## Alternatives considered
**Hand-rolling or vendoring the diff algorithm.** Computing hunks-with-context is a solved problem with sharp edge cases (grouping, context coalescing, the trailing-newline marker). Rather than hand-roll it, `dsh-tool-fs` takes a runtime dependency on the npm [`diff`](https://www.npmjs.com/package/diff) package (a `^9.0.0` range, exact-pinned by the lockfile; it ships its own types) and uses its `structuredPatch`. The repo's default is to vendor Cordis-framework source, but that policy is about the *framework*; a leaf tool package taking a small, well-known, self-typed utility dependency is the same shape as `dsh-acp` depending on `@agentclientprotocol/sdk`. Vendoring a diff algorithm would be re-implementing a battle-tested one for no benefit — the [pre-release "foundation over blast radius"](../../../../AGENTS.md) reasoning does not argue for re-deriving standard algorithms. The dependency's output is normalized in one small module (`packages/fs/tool-fs/src/diff.ts`).
**Hand-rolling or vendoring the diff algorithm.** Contextual hunks have established edge cases, so `dsh-tool-fs` uses the typed [`diff`](https://www.npmjs.com/package/diff) package and normalizes `structuredPatch` output in one module. The repository's vendoring policy applies to its framework source, not every leaf utility.
## Consequences

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@@ -43,7 +43,7 @@ interface TerminalResultView { card: 'terminal'; title?: string; output?: string
### Producer mapping
- `dsh-tool-fs` read → `generic` (`kind:'read'`, a follow-along `location`); write → `diff` (`oldText:null`); edit → `diff` (`oldText:old_string || null`, `newText:new_string ?? ''`). This mirrors `claude-agent-acp`'s `toolInfoFromToolUse` Read/Write/Edit arms field-for-field.
- `dsh-tool-bash` foreground → `terminal` call + `terminal` result; `run_in_background` and `bash_output`/`bash_kill` → `generic`.
- `dsh-tool-bash` foreground → `terminal` call + `terminal` result; `run_in_background` → `generic`. The generic `task_*` controls own their own generic cards.
- `dsh-tool-todo` → `generic`.
### Terminal fallback ownership

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@@ -8,7 +8,7 @@ Status: implemented
The immediate pressure came from skill loading: reading an individual `SKILL.md` can already go through `ctx.get('fs')`, but discovering which skill roots contain `<name>/SKILL.md` or `<name>.md` still needs directory enumeration. Adding directory listing only in `dsh-skill` would either keep a direct Node dependency there or invent a one-off local helper outside the filesystem provider stack.
This branch deliberately lands the provider capability first and does not add a model-facing `ls`/`list` tool or change skill discovery. The follow-up consumer can validate UX and prompt shape separately, while this PR establishes the backend seam and local implementation.
This decision adds the provider capability without a model-facing `ls`/`list` tool or skill-discovery change. Those consumers require separate UX, prompt, and policy decisions.
## Decision
@@ -36,7 +36,7 @@ Broken or disappeared children may be represented as `type: 'other'` without `ve
## Alternatives considered
**Add a model-facing list tool now.** Rejected for this PR. The immediate request is the provider seam, and the user explicitly asked not to change skill loading or other upper layers in this branch. A model-facing tool needs prompt/schema/rendering decisions that should be reviewed separately.
**Add a model-facing list tool with the seam.** Rejected because its prompt, schema, and rendering contracts are independent of the provider primitive.
**Keep directory enumeration in each consumer.** Rejected. That would bind product packages such as `dsh-skill` to Node/local filesystem behavior and bypass policy/remote/sandboxed backends.

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@@ -16,29 +16,29 @@ The assembled system prompt had four defects, all of one family: facts the harne
## Decision
**One principle: every fact in the prompt has exactly one owner.** The model name and workspace are config/session facts → the harness exposes them as variables and the persona references them. Per-tool semantics and when-to-use → the tool's `description`. Cross-call habits a description cannot carry → the tool package's prompt section. Identity and behavior → the deployment's persona, and nothing else.
**One principle: every fact in the prompt has exactly one owner.** The model name and workspace are config/session facts → the harness exposes them as variables and the persona references them. Per-tool semantics and when-to-use → the tool's `description`. Cross-call habits a description cannot carry → the tool package's prompt section. Harness provenance → the static `harness:identity` section. Deployment role and behavior → the deployment's persona.
### Assemble context
`SystemPrompt.assemble(context)` takes an `AssembleContext` — declared EMPTY and merge-extensible in `dsh-system-prompt` (the package stays agnostic of who assembles); `dsh-agent` declaration-merges `agent?: Agent` onto it (a new type-level edge `agent → system-prompt`, no cycle — `tools` already depends on both). The loop passes `{ agent }` each step; section text providers become `string | ((context) => string)` (zero-arg providers stay valid), and the `system-prompt/assemble` waterfall gains the context parameter so a listener can filter or extend per agent.
`SystemPrompt.assemble(context)` takes a merge-extensible `AssembleContext`. `dsh-system-prompt` declares the optional `scope` selector used for scoped routing, while `dsh-agent` declaration-merges the optional typed `agent` field onto it (a type-level edge `agent → system-prompt`, with no runtime dependency cycle). The loop calls `assembleContextFor(agent)` each step so both fields identify the same agent; section text providers may read that context, and the `system-prompt/assemble` waterfall receives it so a listener can filter or extend per agent.
### Prompt variables
Plugins contribute named values via `ctx.systemPrompt.variable(name, provider)`; prompt text references them as `{{name}}`. Providers are functions of the `AssembleContext` and may return `undefined` — "no value for THIS assembly". `assemble()` resolves every registered variable into `PromptAssembly.variables` (waterfall listeners can see, add, or override); `renderPrompt` interpolates. Rendering is STRICT — fail loud beats shipping a malformed prompt: a reference to an unregistered name throws (listing what exists; lookup is `Object.hasOwn`, so a prototype property like `{{constructor}}` is unknown, not a function spliced into the prompt), a registered-but-valueless reference throws, a complete `{{…}}` group that is not a well-formed name (`[a-z][a-z0-9_]*`, e.g. `{{ model }}`) throws, and a `{{` that opens no complete group while a `}}` still follows (`{{{model}}}`, `{{a{b}}`) throws. A lone `{{` with no `}}` anywhere after it is ordinary prose and passes through verbatim; substituted values are never re-scanned. Registration rejects duplicate and unreferenceable names, mirroring the tool registry — and `section()` now rejects duplicate section names, making the documented dedup real.
Plugins register `{{name}}` values through `ctx.systemPrompt.variable(name, provider)`. Assembly resolves them into the waterfall-visible variable map. Rendering rejects unknown own-property references, registered providers that return `undefined`, malformed complete references, and unbalanced references that still contain a closing `}}`; a lone unmatched `{{` remains prose, and substituted values are not rescanned. Registration rejects invalid or duplicate variable names, and section names are unique.
`dsh-agent-loop` registers the two built-ins, both pure projections of the context agent: `model` (= `options.model`) and `cwd` (= `session.header.cwd`). The example personas write `powered by the {{model}} model` — the model name is stated once, in the `model:` config key. `{{cwd}}` is demonstrated in the ACP example only: every ACP session carries the client's cwd, while config-pre-created stdio agents have none (a persona claiming `{{cwd}}` there fails the turn — by design). The variables stay on the loop plugin (unlike the sections below): they are runtime facts of the agents THIS loop drives, and a replacement loop supplies its own.
### Persona as the order-0 section
`dsh-system-prompt` itself registers the two harness-owned sections (they must survive a swapped loop plugin, so they do NOT live on `dsh-agent-loop`): the static `harness:identity` at order `-100` — every prompt opens by stating the agent is powered by the DeepSeek Harness SDK — and `deployment:persona` at order 0, whose text is the plugin's own `persona` config. The persona is per-DEPLOYMENT, not per-agent: every agent in the context (subagents included) renders the same one, `AgentOptions.systemPrompt` is deleted along with the per-agent forwarding plumbing (the app configs' `systemPrompt` keys become a `persona` key routed to this plugin through `dsh-agent-core`), and the ACP bridge and `dsh-tool-subagent` stop carrying persona configuration entirely. The loop's special-case join is deleted: `fullSystemPrompt ≡ renderPrompt(assembly)`, one ordered pipeline for everything the model sees, and `agent/pre-step` (compaction's token-pressure input) measures exactly the real prompt. Order bands are now convention: harness identity `-100`, persona `0`, tool guidance `100199`; other negative orders also render before the persona.
`dsh-system-prompt` owns `harness:identity` at order `-100` and the configured `deployment:persona` at order 0, so both survive a replacement loop. Prompt rendering has one path, `renderPrompt(assembly)`, and `agent/pre-step` therefore measures the exact prompt used for compaction. An agent-scoped `deployment:persona` shadows the global default and lets subagent providers install a persona before publication. The conventional order bands are identity `-100`, persona `0`, and tool guidance `100199`.
### Tool guidance ownership
Per-tool semantics and when-to-use live in tool DESCRIPTIONS, which already ship in every request — the YAML prose was ~fully redundant with them. Sections carry only the cross-call habits a single call's description cannot: `dsh-tool-bash` contributes `tool:bash` (order 105) — check the `[exit code: N]` marker on every result; `dsh-tool-fs`'s read section gains the "not shell commands like cat" contrast. `todo_write` and the subagent tools need NO section their descriptions already carry the whole contract. The leaf personas shrink to identity + behavior (verify your work; keep answers brief), and the welcome banner stops enumerating tools.
Per-tool semantics and selection guidance live in tool descriptions. Prompt sections carry only cross-call habits, such as checking bash exit markers or preferring filesystem tools over shell commands. `todo_write` and subagent tools need no section because their descriptions contain the full contract. Deployment personas contain only role and behavior.
### The subagent context contract
### The subagent conversation-history descriptor
`SubagentProvider` gains `readonly inheritsParentContext: boolean` — a DESCRIPTIVE fact beside `capabilities`, not in it (capabilities are start-time validation; nothing validates against this flag). Spawn and ACP declare `false`, fork declares `true`. `dsh-tool-subagent` derives both the tool description and the `prompt` parameter description from the flag (`providerWording`): the fork instance now tells the model the child inherits the conversation's completed turns (not the in-flight turn) and that its prompt should state only what is new. Deriving the description from a provider that arrives on its own fiber is what forced the provider-lifecycle events and the tool's reactive registration that mechanism, its Loader-concurrency rationale, and its rejected alternatives are recorded in [the provider-lifecycle-events RFC](2026-07-05-subagent-provider-lifecycle-events.md).
`SubagentProvider.inheritsParentContext` describes conversation seeding, not scope, services, tools, or authority. Spawn and ACP set it to `false`; fork sets it to `true`. `dsh-tool-subagent` derives its tool and prompt-parameter descriptions from the flag, including that fork inherits completed turns but not the in-flight turn. Provider lifecycle events keep that wording synchronized with reactive provider registration; their rationale lives in the [provider-lifecycle-events RFC](2026-07-05-subagent-provider-lifecycle-events.md).
## Alternatives considered
@@ -56,10 +56,10 @@ Per-tool semantics and when-to-use live in tool DESCRIPTIONS, which already ship
## Shipped invariants
- `renderPrompt(assemble({ agent }))` for the coding-agent example renders the persona FIRST (with the agent's model name interpolated), then the fs/bash/web guidance sections; the loop has no other prompt-composition path.
- The `subagent_fork` schema description says the child inherits the conversation; the `subagent` one says it does not. The tool follows its provider: absent before the backend activates, present after, gone when the backend unloads, re-worded from the fresh provider on reload.
- Unknown/valueless/malformed/unbalanced `{{…}}` references throw with the section name in the message; duplicate section, variable, and tool-name registrations all throw.
- Snapshot goldens are prompt-independent by construction: llm-replay keys replay on (turn, step) chunk streams and never re-verifies the outgoing request.
- The coding-agent prompt renders identity, persona with the interpolated model, then fs/bash/web guidance through one assembly path.
- Fork and fresh subagent descriptions reflect whether the provider inherits completed conversation turns; the tool appears, disappears, and is reworded with provider lifecycle changes.
- Unknown, valueless, malformed, or unbalanced variable references name the section and throw; duplicate section, variable, and tool registrations also throw.
- Snapshot replay is prompt-independent: it keys recorded chunk streams by turn and step without comparing the outgoing request.
## Consequences

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@@ -4,7 +4,7 @@ Status: implemented
## Problem
Two gaps shared one root. First, provider KV caching (DeepSeek context caching) is prefix-based — a request pays full price only for the tokens after the longest stored prefix it matches — yet nothing in the request pipeline stated, checked, or measured prefix stability: every registered [`PromptSection`](../../../../packages/core/system-prompt/src/index.ts) happened to be static, the tool set happened not to change mid-session, no listener happened to rewrite requests. A single time-interpolating section would have silently multiplied context cost, and no test or metric would have moved. Second, and deeper: the session log — the system's single source of truth — could not actually answer *what the model saw*. It recorded every message but never the system prompt, the tool schemas, or even which model; the mutable `agent/request` waterfall handed listeners the whole `GenerateOptions` to rewrite per call; replay equivalence was therefore a property of the plugin population, not of the design.
The request pipeline did not guarantee prefix stability for provider caching, and the session log could not reconstruct what the model saw. It omitted model, system prompt, and tool schemas while allowing per-call request rewrites. Cache behavior and replay equivalence therefore depended on whichever plugins happened to be loaded.
The reference shape for the happy path is MiniCode's `LLMClient`: a stateful conversation client, appended to — never rebuilt — as the conversation advances, resetting only when the system prompt, tool set, or compaction genuinely changes what the model must see. The design question this RFC answers is how to get that discipline without giving up event-sourcing.
@@ -20,22 +20,22 @@ Prefix-cache stability is corollary #1, not the headline: an append-only log pro
**Messages.** `Session.deriveMessages()` is cached: each surface node is projected exactly once, when first seen, through the public per-node function `deriveEventMessage(event)`; a surface rewrite (a compaction `replace``SurfaceManager.replaceGeneration`) rebuilds. Callers get a fresh array per call over shared, deep-frozen messages: mutating logged history through a projection is unrepresentable (it throws), replacing the old clone-per-call isolation. External reconstructors fold the same public function over a log prefix, so no two paths can disagree.
**The header.** The request's non-content half — `EpochHeader`: call config (`LlmCallConfig`: model + sampling scalars), rendered system prompt, assembled tool schemas — is logged session state, in canonical form (empty system/tools ≡ absent). Two log-only, turn-enclosed events in dsh-session carry it: `request/header`, a full snapshot with reason `'initial' | 'resume' | 'fallback'`, and `request/header-delta`, an amendment (`SystemDelta`: a common-prefix/suffix line trim; `ToolsDelta`: name-keyed added/removed/changed; `config`: replaced whole). The pure trio `foldRequestHeader` / `diffHeader` / `applyHeaderDelta` reconstructs; the live session tracks the fold with the same lazy cursor as the message cache. Snapshots anchor the fold where a fold needs anchors — conversation birth and process boundaries — and each loop instance appends one on its first request (`'initial'` when the log has none, `'resume'` otherwise, even when nothing changed: the boundary itself is a recorded fact, and cross-restart drift becomes attributable while an unchanged header resumes byte-identical). Deltas are an encoding optimization with a safety valve, never a correctness dependency: the writer verifies `applyHeaderDelta(prev, delta)` reproduces the new header exactly and records a `'fallback'` snapshot when the encoding cannot express a change (a pure tool reordering), so a well-formed log always folds.
`EpochHeader` records the request's non-history state: call config, rendered system prompt, tool schemas, and session prefix, with empty values canonicalized to absence. `request/header` writes a full initial, resume, or fallback snapshot. `request/header-delta` encodes system changes by common-prefix/suffix line trim, tools by name-keyed additions/removals/changes, and config or prefix by full replacement. `foldRequestHeader`, `diffHeader`, and `applyHeaderDelta` are the pure codec. Each loop instance writes a snapshot on its first request to anchor process boundaries. Deltas are only an optimization: the writer verifies round-trip equality and falls back to a full snapshot for unrepresentable changes such as pure tool reordering.
**The loop, transmission-stateless.** Per step: render assembly (every step — value comparison needs no change-signal discipline, and a section that varies per step surfaces as a *logged* header event per step instead of a silent bust) → `agent/pre-step` (compaction's surface mutations land before derivation) → **messages snapshot, then `step/start` appended as the next operation in the same synchronous frame** → seed the call config (first request of the instance: from `AgentOptions`, so explicit options always beat the logged baseline — fork model-overrides and resume reconfiguration stay correct; afterwards: from the folded header) → the `agent/request` waterfall, re-typed `(agent, turn, step, config: LlmCallConfig, next) → LlmCallConfig` — a frozen seed and a returned replacement are ALL a listener shapes; content flows through the log channels (`inject()`, steering, prompt-submit `additionalContext`, sections via `system-prompt/assemble`) — → the header event the request owes the log → build `GenerateOptions` from the snapshot + header, deep-freeze (`deepFreeze` exempts the `AbortSignal`, the one live control channel — freezing one breaks `AbortController.abort()`), dispatch. The loop's only in-process bookkeeping is one boolean: whether this instance has logged its anchoring snapshot.
Each step rebuilds prompt assembly. On the instance's first step, `agent/session-prefix` extends a frozen empty seed with request-only opener messages; the result is frozen and cached for that loop instance. `agent/pre-step` then receives the composed prefix before messages are snapshotted immediately ahead of `step/start`. The first call config starts from explicit `AgentOptions`, preserving fork overrides and resume reconfiguration; later calls start from the folded header. `agent/request` may replace only that frozen config seed, while model-visible content enters through logged channels. The loop records the owed header eventthe prefix's only durable home—builds `GenerateOptions` from prefix, snapshot, and header, and deep-freezes it while leaving `AbortSignal` live. Per-instance state is only the cached prefix and whether its anchoring snapshot has been written.
**The reconstruction boundary is `step/start`, unconditionally.** A step's messages are the derivation over `events[0..stepStartSeq)`. Because the snapshot precedes the `step/start` append in the same synchronous frame, nothing can enter this request past the boundary: an `agent.inject()` from an `agent/request` listener (or any concurrent task, or a `session/event` listener firing on `step/start` itself) lands in the log after the boundary and joins the NEXT request. For waterfall-window appends this matches the prior loop (it also derived before its waterfall); for a synchronous `step/start` listener it is a deliberate change — such a listener could previously reach the current request — and `agent/pre-step` is the sanctioned seam for content that must affect the CURRENT request. A step's header for reconstruction is the fold after its own `request/header*` event (which sits between its `step/start` and first response event) or the fold carried forward.
**`step/start` is the reconstruction boundary.** A step derives messages from events before that sequence. Injection after the snapshot joins the next request, and reentrant appends are rejected during event publication. `agent/pre-step` is the seam for content needed by the current request. Header reconstruction folds through the step's own `request/header*` event, or carries the prior fold when no new header is written.
**Enforcement.** Dev-mode ([dsh-invariants](../../../../packages/support/invariants/src/index.ts)), on `llm/stream`: a frozen request with a live `sessionId` — the loop-built marker; hand-built one-shots are unfrozen and skipped — must carry messages deep-equal to the boundary derivation, rebuilt through a FRESH `Session` over `events[0..stepStartSeq)` so the live cache cannot vouch for itself, and header fields equal to `foldRequestHeader` over the log. There is no divergence allowance and nothing to allow: no seam can put unlogged content into a request. `prepend: true` only defends against the replay adapter's short-circuit (an append-registered listener); two prepended listeners have no defined mutual order in cordis, so correctness rests on the seq-bounded fold, never on listener timing. Measurement stays lean: the with-key e2e ([request-cache.e2e.ts](../../../../packages/core/agent-loop/tests/request-cache.e2e.ts)) proves `usage.cacheReadTokens > 0` on every request after the first against the live API, and per-step usage in the log is the production observable — a header event or compaction shows up as a cache-read collapse on the next step.
**Enforcement.** In development, `dsh-invariants` independently rebuilds each loop request through a fresh `Session`, so the live cache cannot vouch for itself, then compares messages and folded header fields at `llm/stream`. Loop requests are identified by their frozen shape and session id; direct one-shots are excluded. Correctness depends on sequence-bounded reconstruction rather than listener order. A with-key e2e requires positive cache-read tokens after the first request; per-step usage is the production signal, and a header change or compaction appears as a cache-read drop on the next step.
### The MiniCode shape: adopted, with the provenance arrow inverted
What survives from `LLMClient`: the conversation is maintained, not rebuilt — one projection per message, ever; requests advance append-only; resets happen only for a system-prompt/tool change, a config change, or compaction, each now a *logged* fact. What is deliberately inverted: MiniCode's client is the source of truth and its event stream derives from client appends (`on_event(MessageAdded)`), which suits an advisory event stream. Here the log is contractual — persistence, crash recovery, fork seeding, transcript rendering, and the snapshot harness all replay it — and it carries strictly more than a message list (turn/step boundaries, raw chunk streams, tool-call pairing, provenance, log-only records), so a message-list client cannot generate it. The arrow therefore points log → client: the conversation state IS the log plus two cached folds inside `Session` (messages, header), and the "client" the loop talks to is the session itself. What the inversion buys over the original: the reconstruction is *checkable* against an independent record on every request — MiniCode's client has nothing to check itself against.
Like MiniCode, the conversation advances append-only and resets only when model-visible state changes. Unlike MiniCode, the event log remains the source of truth because it also owns persistence, recovery, boundaries, tool pairing, and provenance. `Session` caches message and header folds derived from that log, making every request independently checkable.
## Alternatives considered
- **Client as source of truth** (literal MiniCode): a second operative truth beside the log — the two drift and nothing notices; see the section above.
- **A stateful transmission client mirroring the log** (a `PromptPrefix` class holding committed/open message zones with an append/editTail/reset vocabulary, the log pushed into it per event): behaviorally equivalent on the happy path, but it duplicates conversation state outside the session, needs transactional rollback around listener seams, keeps an unlogged content-shaping surface (`editTail`) whose divergence the invariant must specially allow, and still cannot answer "what header did the model see" from the log. Dissolving it into the session's own caches plus logged header events made every one of those problems unrepresentable instead of guarded. (PR #162 is the archaeology of this alternative, three designs deep.)
- **A stateful transmission client mirroring the log** — duplicates conversation state, needs rollback around listeners, leaves an unlogged edit surface, and still cannot reconstruct request headers. Session-owned caches plus logged headers avoid those split truths.
- **Per-call request scalars** (a freely mutable config handed to each `agent/request` dispatch): a listener flips the model per call with zero accounting, silently abandoning the provider cache this design exists to protect. Config is per-conversation logged state; the waterfall proposes, the log records.
- **Detect-and-report** (compare consecutive requests, warn on divergence): catches violations after the fact; a violating request is still constructible and ships. Rejected for interface-level unrepresentability.
- **Event-driven assembly** (re-render only on change signals): a missed-signal bug class — a tool registered mid-session emits `tools/change`, not `system-prompt/change`, and a third-party provider may emit nothing. Per-step render + value compare is robust with zero signal discipline.
@@ -44,6 +44,7 @@ What survives from `LLMClient`: the conversation is maintained, not rebuilt —
## Consequences
- A request that is not explained by the log cannot be constructed by accident — not by the loop, not by a listener; mutating a built request throws; every header change is a durable, diffable log event.
- Choosing between the advisory channels is a change-frequency decision, and the design makes the stable one structural: an `agent/session-prefix` contribution is composed once per loop instance and reused verbatim, so it extends the cacheable prefix at zero marginal cost and CANNOT bust the provider cache mid-session; content that changes mid-session flows through the append-only history channels — `agent.inject()` and tool/prompt-submit `additionalContexts` — each a durable `context/message` paid once and prefix-cached thereafter, at the price of accumulating in history and the log. Route session-frozen openers to the prefix and change notices to the history channels; a per-step request-only tail slot was deliberately dropped (no consumer, and a durable append covers every current update pattern).
- What still costs full price at the provider is inherent and logged: compaction (its `compact/*` events and replace node), a real prompt/tool change (`request/header-delta`), a config switch (ditto), a process boundary with drift (`'resume'` snapshot differing from its predecessor). The provider's own reasoning-content exclusion is managed server-side.
- The `step/start`-listener behavior change (above) is the one observable semantics change for plugins; `agent/pre-step` is the current-request seam.
- Tool-result trimming (planned) needs no new mechanism: a logged single-node surface replace (`start === end`) carrying a trimmed `tool/result` under the same `callId` — compaction-family, replay-correct, cache-bust batched by the same pressure logic.

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@@ -6,7 +6,7 @@ Status: implemented
[The prompt-variables RFC](2026-07-05-prompt-variables-and-tool-guidance-ownership.md) makes `dsh-tool-subagent` DERIVE its model-facing wording from its provider: `SubagentProvider.inheritsParentContext` (spawn/ACP `false`, fork `true`) drives both the tool description and the `prompt` parameter description (`providerWording`), so the fork tool stops lying about context inheritance. That fix created a cross-fiber data dependency: a tool's description is fixed at TOOL REGISTRATION (deliberately — the description is where tool-choice guidance lives), but the provider arrives on its own plugin fiber, on no particular schedule.
The first implementation resolved the provider at the tool plugin's `apply` time and threw when it was absent — an implicit load-order requirement ("list the backend before the tool in cordis.yml"). Review reproduced the failure that requirement hides: the cordis Loader starts sibling entries CONCURRENTLY (`Promise.all` over the group) and `Entry.init()` does not await activation, so a backend whose activation is delayed leaves the tool's fiber permanently failed even when "listed first". The ordering the requirement leaned on is not a contract the Loader offers — "async state is not synchronous state" ([defensive patterns](../../../defensive-patterns.md)).
Resolving the provider at the tool plugin's `apply` time creates an implicit load-order requirement ("list the backend before the tool in cordis.yml"). That requirement fails because the Cordis Loader starts sibling entries concurrently and `Entry.init()` does not await activation: a delayed backend can leave the tool fiber failed even when listed first. The Loader offers no sibling-order guarantee — "async state is not synchronous state" ([defensive patterns](../../../defensive-patterns.md)).
## Decision
@@ -21,7 +21,7 @@ The events also complete the seam's vocabulary: `ctx.subagents` is a named regis
## Alternatives considered
- **Resolving the provider at `apply` time and throwing when absent (a load-order requirement)** — the first implementation, rejected after review reproduced the failure above. Documenting the requirement ("list backends first") would pin a guarantee the Loader does not make.
- **Resolve the provider at `apply` time and throw when absent** — rejected because "list backends first" would claim a Loader ordering guarantee that does not exist.
- **Retrying the lookup (poll until the provider appears)** — converges eventually but invents a private readiness protocol beside the one the framework already has (effect registration + disposal); it also cannot notice a provider LEAVING, so HMR would strand a tool whose wording describes a disposed backend.
- **Section-only subagent wording, lazily resolved at assemble time** — tolerates any load order too, but moves tool-choice guidance out of the DESCRIPTION, contradicting the ownership rule the prompt-variables RFC establishes (per-tool semantics and when-to-use belong in the description). Reactive registration keeps the description authoritative AND order-free.
- **Keying wording off the provider NAME instead of the provider object** — `providerName` is itself config, so a renamed provider silently gets the wrong words; deriving from the resolved provider's own `inheritsParentContext` cannot drift.
@@ -29,6 +29,6 @@ The events also complete the seam's vocabulary: `ctx.subagents` is a named regis
## Consequences
- Consumers deriving state from a named provider react to `subagent/provider-added`/`-removed` instead of reading the registry at `apply` time; `dsh-tool-subagent` is the reference implementation.
- **The two emits carry asymmetric failure semantics, deliberately.** `provider-removed` fires inside the registration's disposer and is delivered with PER-LISTENER containment (the service's `emitLifecycle`, not raw `ctx.emit`, which halts dispatch on the first throw): a throwing subscriber is logged, never starves a later mirror into holding a stale tool, and never disrupts the backend fiber's teardown — dispose reaches quiescence. `provider-added` propagates: it fires at registration time, where a throwing listener unwinds the yielded rollback — the same fail-loud register-time semantics as the system-prompt registries. The run-time backstop bounds what a stale mirror could cost anyway: `start()` re-resolves the provider by name per run, so a tool that outlived its provider fails that call cleanly instead of dispatching into a dead backend. The [events catalog](../../../cordis-catalog/events.md) carries the exact signatures, and the [producer/consumer map](../../../event-producer-consumer.md) shows `dsh-subagent` emitting and `dsh-tool-subagent` consuming both events.
- **Addition fails loud; removal is contained per listener.** An addition listener may unwind registration. Removal runs during disposal, so one throwing listener is logged without starving later mirrors or disrupting teardown. `start()` still resolves the provider by name for every run, preventing stale tools from calling a removed backend. See the [events catalog](../../../cordis-catalog/events.md) and [producer/consumer map](../../../event-producer-consumer.md).
- **A window where the tool is absent.** Between backend disposal and re-registration (an HMR reload), the model sees no subagent tool. This is the honest state — the alternative is a tool that dispatches into nothing — and the tool registry's `tools/change` emit keeps prompt assembly current.
- **Two waiting fibers sharing a `toolName` is an invalid config caught late.** If two loads of `dsh-tool-subagent` name different providers but the same `toolName`, both wait, and whichever provider arrives first registers; the second registration throws only when ITS provider arrives. `TODO(subagent-dup-toolname)` in the plugin records this blast radius; the tool registry's duplicate-name rejection remains the backstop.

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@@ -0,0 +1,96 @@
# RFC: A shared timeout/deadline primitive, with hard-kill left to each capability
Status: implemented
## Problem
Timeout handling was drifting apart across the tool-bearing capabilities, and the divergence was not superficial — it was the same logic re-implemented three ways, each with its own subtle correctness burden.
- **bash** ([packages/bash/bash-local/src/run.ts](../../../../packages/bash/bash-local/src/run.ts)) had a full, correct timeout inside the process plumbing: a config-clamped `timeoutMs`, two independent triggers — a `killTimer` for the timeout and an `onAbort` listener for upstream cancellation — each calling one `kill()` closure that escalates SIGTERM→grace→SIGKILL on the process group, and two orthogonal outcome booleans (`timedOut`, `aborted`) latched independently.
- **web_fetch** ([packages/web/web-fetch-local/src/provider.ts](../../../../packages/web/web-fetch-local/src/provider.ts)) had a correct but *hand-rolled* timeout: it constructed an `AbortController`, wired `setTimeout(() => controller.abort(new WebError(…, 'WEB_FETCH_TIMEOUT')))`, manually added and removed the upstream-signal listener, cleared the timer in a `finally`, and recovered the timeout reason from `signal.reason` in a `translateAbortOrNetwork` helper because the reader surfaces a bare `AbortError`.
- **web_search** ([packages/web/tool-web/src/search.ts](../../../../packages/web/tool-web/src/search.ts)) had **no timeout at all**: `WebSearchRequest` ([packages/web/web/src/types.ts](../../../../packages/web/web/src/types.ts)) carries no `timeoutMs` field, and each provider's `search()` only forwards `exec.signal`. (web_search stays untimed here — see Consequences.)
Each new external-process or network tool re-derived the same four things — clamp the requested value, start a timer, fuse the timeout with upstream cancellation, and distinguish "timed out" from "cancelled" on the way out — and the fusion and reason-recovery are exactly the parts that are easy to get subtly wrong (web_fetch's `signal.reason` dance is evidence). At the same time, the *termination* each performs is irreducibly different: bash kills an OS process group (work runs in a child process, outside this runtime, reachable only by signal), while web aborts an in-process `fetch` (undici tears down the socket). There is no single mechanism that can stop all of them.
## Decision
`@deepseek-ai/dsh-timeout` lives under `packages/util/` (peer to `dsh-brand`) and owns the *timing and classification* half of timeout; the *termination* half — the hard kill — stays in each capability's implementation. It is a library of pure functions, **not** a cordis service or plugin: it takes no `ctx`, registers nothing, holds no cross-call state, and emits no events. There is deliberately no central "timeout service" that would have to know how to stop every capability's work — that knowledge is exactly what a microkernel keeps out of shared layers, and what Codex's exec-only `ExecExpiration` scope demonstrates.
### The library surface
Three functions plus one reason type:
```ts ignore-check
/** The internal reason attached to a timeout abort, so consumers can classify it after the fact. */
export class TimeoutReason extends Error {
override name = 'TimeoutReason'
constructor(readonly code: string, readonly timeoutMs: number) {
super(`${code} after ${timeoutMs}ms`)
}
}
/** Validate/fill a caller's optional positive hint from the backend's default, then cap at its max. */
export function clampTimeout(
requested: number | undefined,
def: number,
max: number,
name = 'timeoutMs',
): number
/**
* Build a deadline signal that aborts on upstream cancellation OR on timeout,
* with the timeout carrying a `TimeoutReason`. `timeoutMs <= 0` means "no
* timeout" (background tasks): forward only the upstream signal, arm no timer.
* The returned object's `[Symbol.dispose]` clears the timer — `using` for a
* scope-lifetime consumer, a manual call for an event-lifetime one.
*/
export function deadline(
upstream: AbortSignal | undefined,
timeoutMs: number,
code: string,
): { signal: AbortSignal; [Symbol.dispose](): void }
/** Recover the TimeoutReason from an aborted signal (or error); `code` scopes the match to this deadline's timer. */
export function timeoutOf(x: AbortSignal | { reason?: unknown }, code?: string): TimeoutReason | undefined
```
`deadline` fuses an upstream signal with a timer through `AbortSignal.any`, adds a typed `TimeoutReason`, and exposes disposable timer cleanup. Non-positive timeouts are an internal no-timeout sentinel for backend-owned background work; external hints pass through `clampTimeout` and must be positive and finite. Without a timer or upstream signal, the function returns a never-aborting signal with the same disposal shape. Providers translate timeout reasons into seam-specific results. `timeoutOf(signal, code)` scopes classification so an outer nested deadline is treated as upstream cancellation rather than the inner capability's timeout.
### The division of labor
| Concern | Owner |
|---|---|
| Validate request hint and clamp default/max | `dsh-timeout` (`clampTimeout`) — pure arithmetic plus the shared positive-finite request contract |
| Arm timer, abort on deadline, carry reason, fuse with upstream cancel | `dsh-timeout` (`deadline`) |
| Clear the timer | `dsh-timeout` (`[Symbol.dispose]`) |
| Classify the first abort reason after abort | `dsh-timeout` (`timeoutOf`) |
| **Actually terminate the work** | the capability's implementation |
| The default/max *values* | the capability's config |
| The timeout `code` string | the capability (`WEB_FETCH_TIMEOUT` ≠ `BASH_TIMEOUT`) |
The signal only *notifies*; termination is always the listener's job, and the listener differs by capability. bash writes its own `addEventListener('abort', kill)` because the OS process lives outside this runtime and nothing else will kill it; web hands `d.signal` to `fetch` and undici tears down the socket. This is why file read/write/edit take **no** `timeoutMs`: a local syscall is best-effort-abortable at most, a timeout could not force `fsync`/`rename` to stop, and adding one would be an implicit default that violates explicit-over-implicit. Both reference agents leave file I/O untimed for the same reason.
### How each capability consumes it
- **web_fetch** — the tool stays validate-and-forward; the provider's hand-rolled controller + `setTimeout` + manual listener + `finally` + `signal.reason` recovery is replaced by provider-owned `deadline`/`timeoutOf`. A pre-aborted upstream signal still throws `WEB_ABORTED` up front; otherwise `fetch` runs against the fused `d.signal`, and `translateAbortOrNetwork` classifies a thrown error by the signal (`timeoutOf` → `WEB_FETCH_TIMEOUT`, else aborted → `WEB_ABORTED`, else network → `WEB_PROVIDER_ERROR`). The public error-code contract is unchanged, and `TimeoutReason` never crosses the web seam as the public error.
- **bash** — `resolve()` clamps the request into an explicit spec. Foreground `run()` creates the deadline and passes its signal to process execution, whose existing abort listener performs the process-group kill. The executor classifies the first abort as timeout or cancellation. Background starts remain timeout-free and forward only upstream cancellation.
## Consequences
- `runBash`'s outcome no longer independently latches `timedOut` and `aborted`; a timeout and a user abort racing before process close now report a single first-abort cause instead of both being true. The uniform SIGTERM→grace→SIGKILL kill is unchanged, and the seam type `BashRunResult` keeps both booleans (now mutually exclusive), so `dsh-tool-bash`'s result rendering is untouched.
- `SpawnSpec.timeoutMs` and `SpawnOutcome.timedOut`/`aborted` were removed rather than kept as always-zero/always-false vestiges: with `runBash` owning no timer and the executor owning classification, they were read nowhere. This is the one deviation from the literal proposal shape (which passed `timeoutMs: 0` into `runBash`); an always-0 field read by nothing is dead weight under the per-file coverage gate.
- web_fetch shed its bespoke controller/timer/listener/reason-recovery; the classifier now keys off the deadline signal (`timeoutOf` + `aborted`) rather than the thrown error's shape, which is robust across both the request-phase reject-with-reason and the read-phase bare-`AbortError`.
- `AbortSignal.any` and `using`/`Symbol.dispose` enter the repo for the first time here (Node ≥ 24 baseline, already met).
Out of scope, named to mark the boundary: `web_search` can gain an optional model-facing `timeout_ms` once its tool-schema/snapshot coverage is planned; future ripgrep-backed fs discovery tools can consume the same provider-owned deadline shape once they exist; a `tools/execute` waterfall middleware could arm a default deadline for every tool call by driving `exec.signal` — that would be a plugin that *consumes* this library and still only notifies, the hard kill remaining each capability's job.
## Alternatives considered
**A unified timeout *plugin* / `ctx.timeout` service.** Rejected on microkernel grounds. A service that could stop any tool's work would have to understand every capability's termination mechanism (process-group SIGKILL, socket teardown, syscall-boundary checks) — the "kernel knows too much" the architecture forbids. Codex's `ExecExpiration` is scoped to the exec family precisely because the kill it drives (`killpg`) is process-family-specific; MCP and model-stream keep their own. There is no coherent middle layer that owns termination for everything, so the shared piece can only be the pure timing/classification half — a library, not a service.
**Per-tool ad-hoc timeout, no shared code (the prior status quo, and Claude Code's choice).** Rejected because it was already producing divergence and duplicated correctness burden: web_fetch hand-rolled the exact controller/reason logic that future network/process-backed tools would each have to re-derive, and the fusion + `signal.reason` recovery are the error-prone parts. Claude Code tolerates full duplication; this repo has a single shared abort channel (`exec.signal` on every `execute`) that makes a small shared primitive strictly cleaner, so the cost/benefit differs.
**A `withTimeout(promise, ms)` wrapper instead of a signal factory.** Rejected because racing a promise against a timer resolves the *tool-call* promise on deadline without stopping the underlying work — the child process or fetch socket leaks on. Handing out a signal and requiring the capability to listen is what forces a real termination path to exist. This mirrors the "dispose must reach quiescence, not just request it" defensive rule.
**Keep separate bash timeout and cancellation triggers.** Rejected because one deadline signal removes the bespoke timer and standardizes classification. Racing causes report whichever abort arrived first, while the existing SIGTERM-to-SIGKILL termination path remains unchanged.

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# RFC: Tool result retention library
Status: implemented
## Problem
Several model-facing tools already bound the amount of context they return, but each one owns a different local mechanism and vocabulary: bash keeps a tail plus spill files, web search caps source lists, web fetch caps body content, and `glob` / `grep` discovery needs an inline first page while keeping exact omission metadata for the full result set. A single `truncate(text)` helper cannot cover those cases: item tools need item counts and grouping outside the primitive, while text tools need byte budgets and UTF-8-safe head/tail cuts.
The shared abstraction the tools need is **retention**, not generic collection. A caller feeds items or text chunks into a bounded object and later receives the retained content plus exact omission metadata. Tool-specific code still owns business semantics: file grouping, line numbering, exit codes, provider error states, spill files, and model-facing prose. The common library owns only the mechanical question "what did we keep, and what did we omit?"
## Decision
`@deepseek-ai/dsh-retention` lives under `packages/util/` (peer to `dsh-brand` and `dsh-timeout`) and owns bounded model-facing output. It is a library of pure classes and functions, **not** a Cordis service or plugin: it takes no `ctx`, registers nothing, holds no cross-call state, and emits no events. Tool packages import it directly when they need bounded output.
The library has two independent retainers:
- `ItemRetainer<T>` handles ordered logical units such as paths, grep matches, or search sources. It supports `head` retention only in v1, while keeping the retainer shape open to additional retention strategies later.
- `TextRetainer` handles byte-oriented text streams such as bash stdout/stderr or web response bodies. It supports `head`, `tail`, and `headTail` retention while preserving UTF-8 boundaries at `finish()`.
Both retainers return a small `PushDecision` after each `push()` so callers can tell whether that unit/chunk was fully retained and whether the accumulated result is now truncated. Omission counts are exact because callers keep feeding every observed item/chunk.
```ts ignore-check
/**
* How much content the retainer omitted.
*
* `unknown` is reserved for callers that omit without a count; the retainers
* themselves return `none` or `exact`.
*/
type Omitted =
| { kind: 'none' }
| { kind: 'exact'; count: number }
| { kind: 'unknown' }
interface PushDecision {
kept: boolean
truncated: boolean
}
/**
* Final result for ordered logical units.
*/
interface RetainedItems<T> {
items: T[]
truncated: boolean
seen: number
kept: number
omitted: Omitted
}
/**
* Final result for text streams.
*
* The returned `text` is safe to send to a formatter; the retainer does not add
* tool-specific headers, exit markers, XML tags, or recovery instructions.
*/
interface RetainedText {
text: string
truncated: boolean
omittedBytes: Omitted
}
```
### Strategies
Item retention supports a head window. Text retention supports head, tail, and headTail byte windows.
```ts ignore-check
type ItemRetentionStrategy =
| {
/** Keep the first `maxItems` units. Use for `glob`, `grep`, and web sources. */
kind: 'head'
maxItems: number
}
type TextRetentionStrategy =
| {
/** Keep the first `maxBytes` bytes. */
kind: 'head'
maxBytes: number
}
| {
/** Keep the final `maxBytes` bytes. Requires reading to the end. */
kind: 'tail'
maxBytes: number
}
| {
/** Keep a stable prefix and suffix, omitting the middle. Requires reading to the end. */
kind: 'headTail'
headBytes: number
tailBytes: number
}
```
### Tool mapping
`read` is intentionally outside the v1 retention library. Its `read-render` helper owns a file-specific pagination contract: `offset` / `limit`, line numbers, `totalLines`, offset-out-of-range errors, per-line preview truncation, and a selected-output byte cap that can stop scanning mid-window. That is a line-window renderer, not a generic retention primitive. It may share future neutral notice helpers, but it should not pass its already-selected window through `ItemRetainer`.
`FsGlobEntry` and `FlatGrepMatch` below are the intended discovery-tool item shapes, not existing retention-library exports. `FsGlobEntry` is one backend-derived path, and `FlatGrepMatch` is one ungrouped grep match before the backend groups retained matches by file.
`glob` uses `ItemRetainer<FsGlobEntry>` with `{ kind: 'head', maxItems: globMaxResults }` after collecting the full sorted path list. The tool keeps the retained first page inline and may save the full list through the spill seam. Path mapping, skipped candidates, and `incomplete` stay outside the retainer.
`grep` uses `ItemRetainer<FlatGrepMatch>` with `{ kind: 'head', maxItems: grepMaxMatches }` before grouping. The executor parses ripgrep output, maps paths, applies per-line preview truncation, and pushes flat matches. After `finish()`, the tool groups retained matches by file and can save the full match list through the spill seam when the inline result is capped. Grouping is not part of the retainer because the cap is total matches, not files; per-match preview truncation and `incomplete` are also separate from result-level retention.
`bash` can use `TextRetainer` with `tail` or `headTail` and reads to process completion. The bash executor still owns spill files, exit status, signal, timeout, and background-task behavior; the retention helper only replaces ad hoc in-memory head/tail accounting where that behavior is desired. Long-running task ownership remains orthogonal to the [generic long-running tool runtime](2026-06-20-generic-long-running-tool-runtime.md).
`web_fetch` can use `TextRetainer` with `head` or `headTail`, or keep provider-owned body caps when the provider must read and decode internally. Either way, the fetch result's `truncated` remains a provider/tool fact, and the library only supplies retained text and omission metadata.
`web_search` can use `ItemRetainer<WebSearchSource>` with `head`. Current providers often return an array, so this is post-hoc but still standardizes notices.
### Notices
The library exposes a neutral notice shape and a tiny formatter hook, but tools provide the user-facing words. A grep footer says "Narrow the pattern, path, or include"; a web fetch footer says "Fetch a more specific URL or section"; bash may point to a spill file. The retainer cannot know those recovery actions.
```ts ignore-check
interface RetentionNotice {
scope: string
strategy: 'head' | 'tail' | 'headTail'
unit: 'items' | 'bytes' | 'chars' | 'lines'
limit: number | { head: number; tail: number }
kept: number
omitted: Omitted
}
const formatGrepNotice = (notice: RetentionNotice): string =>
formatRetentionNotice(
notice,
({ kept }) => `Results capped at ${kept}. Narrow the pattern, path, or include to see more.`,
)
```
The formatter hook is deliberately small: a tool turns a `RetentionNotice` into its own footer text. The helper may standardize omission wording, but it does not own recovery guidance.
`truncated` means the retainer omitted otherwise-available content because of a budget. It does not mean the upstream was incomplete. Tools keep separate fields for permission failures, skipped binary files, provider partial failures, unreadable candidates, invalid UTF-8, and any other "could not inspect" condition.
## Consequences
**What shipped.** `@deepseek-ai/dsh-retention` exports `ItemRetainer`, `TextRetainer`, the result types (`RetainedItems`, `RetainedText`), the strategy types (`ItemRetentionStrategy`, `TextRetentionStrategy`), `Omitted`, `PushDecision`, `RetentionNotice`, and the neutral notice helpers `describeOmitted` / `formatRetentionNotice` — with no dependency on Cordis or any tool package. Unit tests cover item-head retention with exact omission counts, text-head retention, text-tail retention, head-tail byte retention, zero budgets, UTF-8 boundary handling (2-, 3-, and 4-byte codepoints and invalid lead bytes at each cut), and unknown omission wording.
**What is documented but not yet migrated.** `glob`, `grep`, `bash`, `web_fetch`, and `web_search` have their mappings documented in the [package README](../../../../packages/util/retention/README.md), but not every tool has been migrated onto the library in this change; migration is deliberately separate follow-up work. `read` is documented as intentionally out of scope: its `read-render` line-window contract (`offset`/`limit`, `totalLines`, offset-range errors, per-line preview truncation, a byte cap over the selected window) is not generic retention, and one `Omitted` count cannot represent both sides of a line window.
**Boundaries the library holds.** `truncated` means the retainer omitted otherwise-available content because of a budget; it never means the upstream was incomplete. Tool-specific states — `incomplete`, permission failures, provider partial failures, binary skips, bash spill-path recovery, invalid UTF-8 — stay in tool-domain fields, outside the retainer. When a future change migrates a tool, that package's README and tests must prove the model-facing result text is unchanged except for deliberate notice wording.
**Tradeoffs accepted.** The v1 surface deliberately supports only item `head` retention and text `head` / `tail` / `headTail`; windows, grouped budgets, sort-aware caps, and upstream-stop control wait until a second consumer proves the need. Text retention counts bytes for process/body safety, leaving character- and line-level preview budgets as separate tool-owned concerns.
## Alternatives considered
**Post-hoc `truncate(text)` only.** Rejected: it matches Codex's history/tool-output truncation use case but loses item counts, grouping boundaries, UTF-8-safe byte windows, and exact omission metadata.
**One generic `Collector<T>` with pluggable callbacks.** Rejected for v1: it hides the two important resource modes. Logical item retention counts items; text retention counts bytes and preserves UTF-8 boundaries. Separate `ItemRetainer` and `TextRetainer` names make that difference explicit while keeping the API small.
**Put `read` windowing behind `ItemRetainer`.** Rejected for v1: `read` is the only current window consumer, and its semantics are file pagination rather than generic retention. A single `Omitted` count cannot represent both sides of a line window, and `read` also carries `totalLines`, offset-range errors, per-line preview truncation, and a byte cap over selected output. Keeping `read-render` tool-owned avoids growing the shared library around one special case.
**Make truncation part of `ToolExecutionResult`.** Rejected: the tool registry would have to understand tool-specific recovery guidance, grouping, line numbering, exit status, and provider semantics. Retention is a library used before a tool returns `ContentBlock[]`; the model-facing result remains tool-owned.
**Expose limits in every model-facing tool schema.** Rejected as the default: Claude Code's grep exposes `head_limit` / `offset`, but this harness keeps routine budgets as deployment config unless the model genuinely needs pagination control. A future read-like continuation field can be added per tool; it does not belong in the shared retention primitive.

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# RFC: Tool-call timeout policy as a plugin
Status: implemented
## Problem
The [timeout/deadline RFC](2026-07-06-timeout-deadline-library.md) extracted the timing-and-classification primitive into `@deepseek-ai/dsh-timeout`, but timeout policy was still attached to individual capabilities and model-facing schemas. `bash` exposed `timeoutMs`; `web_fetch` exposed `timeout_ms`; `web_search` had no model-facing timeout even though providers already honor `exec.signal`; a future grep/glob tool would either import the timeout library directly or invent its own timeout policy. That is the wrong authoring shape for a plugin SDK: a tool author should normally forward `exec.signal` to the implementation it calls, and deployment policy should decide the budget.
At the same time, not every timeout in the repo is a model-facing tool-call budget. Hooks execute command hooks by calling `ctx.bash` directly, not through `ctx.tools.execute()`, and the `bash` model tool multiplexes foreground execution, background start, background polling, and hook reuse through the same backend. Moving every timeout into a tool plugin in one step would conflate those paths and risk breaking hook timeout semantics.
## Decision
Tool-call timeout is a policy that applies only to model-facing tool execution, in three parts:
- `@deepseek-ai/dsh-timeout` remains the shared library that owns `deadline()` and `timeoutOf()`.
- `@deepseek-ai/dsh-tools` has an around-dispatch waterfall, `tools/execute`, between `tools/pre-execute` and `tools/post-execute`.
- `@deepseek-ai/dsh-timeout-policy` reads each tool's declared `timeoutMs` from the registry and wraps a call that has one by deriving a new `exec.signal`.
The execution pipeline is:
```text
ctx.tools.execute(exec)
-> tools/pre-execute
-> tools/execute
-> registry dispatch (the base next())
-> tool.execute(args, exec)
-> thrown tool errors normalize to ToolExecutionResult
-> tools/post-execute
```
The default behavior is conservative: a tool that declares no `timeoutMs` receives no `TOOL_TIMEOUT` deadline from the plugin.
### The `tools/execute` around seam
`@deepseek-ai/dsh-tools` declares a `tools/execute` waterfall whose base `next()` is the dispatch-with-normalization thunk — the same inner `try`/`catch` that turns a thrown tool (or unknown tool) into an `isError` `ToolExecutionResult`. A listener receives `(exec, next)`: it calls `next()` to delegate to dispatch (returning its result, optionally wrapped) or returns a replacement result to short-circuit dispatch. The whole pipeline still sits inside `execute`'s outer try/catch, so a throwing listener becomes an `isError` result, never a turn failure.
That the catch is the base `next` — not something outside the waterfall — is load-bearing: when a provider sees the timeout signal and throws its own upstream-abort error, registry dispatch first converts it to a normal error result, and only then can `timeout-policy` replace the final result with `TOOL_TIMEOUT`.
### The `timeout-policy` plugin
The plugin is `@deepseek-ai/dsh-timeout-policy`, a zero-config function/namespace plugin (`name` / `inject` / `apply`) in the `packages/timeout/` group. The per-tool budget is DECLARED on the tool, not on this plugin: a `ToolDefinition` carries an optional `timeoutMs`, which the owning tool plugin sets from its own config. `dsh-tool-web`, for example, resolves `fetchTimeoutMs` / `searchTimeoutMs` (default 30000) onto the `web_fetch` / `web_search` definitions:
```yaml
- id: timeout-policy
name: '@deepseek-ai/dsh-timeout-policy'
- id: tool-web
name: '@deepseek-ai/dsh-tool-web'
config:
fetchTimeoutMs: 30000
searchTimeoutMs: 30000
```
Timeouts live on tool definitions rather than a free-text name map, eliminating misspelled unused policy. `defineTool` validates a positive finite budget. During dispatch the enforcer derives a deadline signal, restores the caller signal afterward, and converts its own expiry into `TOOL_TIMEOUT`; tools without a budget pass through unchanged.
Signal replacement is by **in-place mutation of `exec.signal`**, not by passing a new object to `next()`. Cordis's waterfall `next()` ignores any arguments handed to it and re-invokes downstream listeners with the shared payload array (`vendor/cordis/src/events.ts`), so the documented cordis idiom — mutate the shared object, then delegate — is the only mechanism that reaches dispatch. The plugin restores `exec.signal` to the caller's original in a `finally` so `tools/post-execute` never sees this plugin's (possibly already-aborted) deadline signal.
`timeout-policy` owns both uses of the `TOOL_TIMEOUT` code: the internal deadline code passed to `deadline()`/`timeoutOf()` (scoped so a nested outer deadline reads as an ordinary cancel) and the structured tool-result error code. Its replacement result is:
```ts ignore-check
function toolTimeoutResult(timeoutMs: number): ToolExecutionResult {
return {
content: [{ type: 'text', text: `Error: tool call timed out after ${timeoutMs}ms` }],
isError: true,
error: { name: 'ToolTimeoutError', code: 'TOOL_TIMEOUT' },
}
}
```
This is a cooperative deadline. It does not kill arbitrary work by racing the tool promise; the tool or the capability it calls must honor `exec.signal` and reach quiescence. Declaring `timeoutMs` therefore MEANS "this tool is cooperative with `exec.signal`", which the plugin README states as its contract.
No new session event is needed for reconstructability: `TOOL_TIMEOUT` is the final model-facing `tool/result` for that call, so the existing session log already records the content and structured `{ name, code }` error the next model request sees.
### Existing tool adaptation
`web_fetch` and `web_search` are migrated. `dsh-tool-web` keeps ownership of their model-facing schemas, and those schemas expose no timeout knob: `web_fetch` dropped its `timeout_ms` parameter to match the reference-agent shape, and `web_search` stays query-only. The tool bodies do not import `@deepseek-ai/dsh-timeout`; they forward `exec.signal` to `ctx.web`.
`dsh-web-fetch-local` keeps one configured provider-level `timeoutMs` as a large resource backstop for direct `ctx.web.fetch()` callers and misconfigured deployments; it owns no model-facing timeout. When a `TOOL_TIMEOUT` signal reaches the fetch provider first, provider-scoped classification treats it as upstream `WEB_ABORTED`, and the outer `tools/execute` wrapper replaces the final tool result with `TOOL_TIMEOUT`. A shipped web-tool deployment configures the provider backstop above the `timeout-policy` budget so the tool-call policy normally wins for model calls.
`bash` stays on the current backend timeout path. `dsh-tool-bash` continues to expose `timeoutMs` and `run_in_background`; `dsh-bash-local` continues to use `@deepseek-ai/dsh-timeout` for `BASH_TIMEOUT`; hook bridges continue to call `runHook()` and pass `timeoutMs` through `ctx.bash`. This keeps foreground/background/hook behavior stable.
`read`, `write`, `edit`, `todo_write`, `task_list`, and `task_kill` do not opt into tool-call timeout. `task_output` owns its bounded wait because a wait timeout is a successful live-status result, not a tool failure.
A future model-facing grep/glob tool can be implemented on top of `ctx.bash` without importing `@deepseek-ai/dsh-timeout`: it forwards `exec.signal` to `ctx.bash`, and declares its own `timeoutMs` (from its plugin's config) for the enforcer to apply. If bash-local's backend timeout becomes a problem for such a tool, the bash seam can later add a caller-owned-deadline mode; that is outside this cut.
## Alternatives considered
**Name the plugin `tool-timeout`.** The literal RFC name matched the `gen-tool-catalog` completeness guard's `packages/*/tool-*` glob, which requires every match to register a model-facing tool. This plugin registers none — it is a `tools/execute` wrapper — so a `tool-*` name would either fail `verify-tool-catalog` or force a misleading boot entry. The package is `@deepseek-ai/dsh-timeout-policy` in a new `packages/timeout/` group; the cordis.yml `id` can still be `timeout-policy`.
**Keep per-tool timeout handling only.** This was the shape for `bash` and `web_fetch`, and it matches Claude Code and Codex for shell commands. It loses for web-style tools because every new timeout-capable tool must choose validation, cap semantics, docs, snapshots, and classification. The plugin centralizes policy and classification while leaving each tool's schema focused on business input.
**Move all timeout policy out of bash-local immediately.** Cleaner long-term — bash-local would become a pure subprocess executor and all callers would own their deadlines. It loses as the first step because hooks call `ctx.bash` directly and the bash model tool has foreground/background semantics that are not the same tool-call lifetime. Keeping `BASH_TIMEOUT` preserves those paths while tool-call timeout proves itself on simpler tools.
**Use a global default budget for every tool.** Convenient, but it surprises tool authors: any tool that accidentally runs longer than the global budget would start failing once the plugin loads. A per-tool declared budget makes adoption deliberate.
**Expose a model-facing `timeout_ms` override.** Claude Code's `WebFetch`/`WebSearch` and Codex's web tools keep timeout out of the model-call shape. A model override would make timeout part of prompt semantics and force schema/argument-stripping rules into `timeout-policy`. Web timeout stays deployment policy only.
**Let `timeout-policy` match tool arguments itself.** A rule engine such as "disable timeout when `bash.run_in_background` is true" would make the policy plugin know tool-specific argument semantics. Avoided by not migrating bash to tool-call timeout.
**Use `tools/pre-execute` plus `tools/post-execute` instead of a new around seam.** A pre listener could arm a deadline and mutate `exec.signal`; a post listener could classify and replace. That loses because the deadline lifetime would cross two independent waterfalls: a call-id map, cleanup on every pre-deny/tool-throw/post-throw/dispose path, and ordering rules with every other listener. `tools/pre-execute` is also the allow/deny gate, not an execution wrapper. `tools/execute` gives the timeout one lexical scope: arm, delegate, classify, dispose.
**Use `Promise.race` to enforce timeouts for non-cooperative tools.** Rejected for the same reason as the timeout-library RFC: it returns control to the caller while the underlying process, fetch, or provider operation may still be running. The plugin only sends a signal; termination remains the implementation's responsibility.
## Consequences
- `@deepseek-ai/dsh-tools` gains an around-dispatch surface after the interception seams deliberately split pre/post tool hooks. Its contract is narrow — wrap registry dispatch, not replace the pre-gate or post-result policy — and the base `next()` is dispatch-with-normalization so a wrapper never sees a raw tool throw.
- Multiple `tools/execute` listeners compose by ordinary Cordis waterfall order: a listener that calls `next()` wraps downstream listeners plus dispatch; one that returns without `next()` short-circuits them. A deployment combining timeout with a future retry/sandbox/metrics wrapper chooses semantics by registration order ("timeout covers the whole retry" vs "timeout covers each attempt").
- Opt-in by declaration is a deliberate misconfiguration risk: a tool can declare a `timeoutMs` without honoring `exec.signal`, and that tool will not stop on timeout. The plugin contract states that declaring a budget means cooperative; the web tools prove the pattern on tools that already forward the signal.
- During the transition `bash` and the migrated web tools use different timeout paths on purpose: `TOOL_TIMEOUT` is the model-facing tool-call budget, while `BASH_TIMEOUT` remains the bash backend timeout used by bash and hooks.
- Deviation from the literal proposal, recorded per the implemented-RFC rule: the plugin package is `@deepseek-ai/dsh-timeout-policy` (not `tool-timeout`), signal replacement is in-place `exec.signal` mutation before `next()` (not `next({ ...exec, signal })`, which cordis ignores), and the per-tool budget is declared on the `ToolDefinition` (`timeoutMs`, set by the owning tool plugin from its config) rather than mapped by tool name in this plugin's config — so the enforcer is zero-config and a mistyped tool name is impossible. All three are described in `## Decision` above.

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# RFC: The agent is a registration scope
Status: implemented
## Problem
One application needs to share infrastructure across many agents while letting each agent have its own tools, prompt contributions, policies, and listeners. Shared adapters, persistence, and user interfaces belong to the deployment; a persona, tool variant, or listener often belongs to one agent.
A separate service graph per agent duplicates shared infrastructure. One global registration graph has the opposite failure: an agent-specific contribution can leak into unrelated agents. Contributors need one ordinary registration mechanism that determines both who can see a contribution and when it is cleaned up.
The mechanism also needs a publication boundary. An agent must not become visible before its local world is complete, and teardown must retain that world until final work has stopped.
## Decision
Every live agent owns one flat registration layer exposed as `agent.ctx`. Code registers through the context that owns a contribution; scope-aware services combine deployment-global registrations with exactly one matching agent layer; operations choose that layer from their real agent; and the layer exists for the agent's complete published lifetime.
Cordis is the plugin framework underneath the SDK. A Cordis **context** is the object plugins use to access services and register effects whose cleanup follows that context. The [Cordis primer](../../../cordis-primer.md) explains the framework in more detail.
For most contributors, the complete contract is four rules:
| Question | Rule |
|---|---|
| Where do I register behavior for one agent? | Call the ordinary registration API through `agent.ctx` |
| What does an operation for an agent see? | Deployment globals plus that agent's layer, using the owning service's merge rules |
| Which scoped listeners run? | Unscoped listeners plus listeners registered for the operation's agent |
| How long does the layer exist? | Setup completes before publication; disposal keeps it until work reaches quiescence |
The scope is flat. Resolution never walks parent or sibling scopes, and lifetime ownership does not imply registration inheritance.
```mermaid
flowchart LR
plain["Plain plugin context<br/>cleanup follows the plugin"] -->|"registers into"| globalLayer["Deployment-global layer"]
agentAContext["agentA.ctx<br/>cleanup follows Agent A"] -->|"registers into"| agentALayer["Agent A layer"]
agentBContext["agentB.ctx<br/>cleanup follows Agent B"] -->|"registers into"| agentBLayer["Agent B layer"]
operationA["Operation for Agent A"] -->|"selects"| agentAView["Agent A view<br/>globals plus A local"]
globalLayer --> agentAView
agentALayer --> agentAView
operationB["Operation for Agent B"] -->|"selects"| agentBView["Agent B view<br/>globals plus B local"]
globalLayer --> agentBView
agentBLayer --> agentBView
```
The missing cross-edges are the isolation rule: Agent A's local registrations do not enter Agent B's view, and a parent's registrations do not enter a child merely because the parent owns the child's lifetime.
The companion [runtime-design RFC](2026-07-12-agent-scope-runtime-design.md) explains the implementation and correctness reasoning. The [subagent composition-controls RFC](../feature/2026-07-12-subagent-persona-tool-filter-and-depth.md) owns the separate `persona`, `toolFilter`, and `maxDepth` feature.
### Registration origin chooses visibility and cleanup
A registration made through a plain plugin context is deployment-global and is disposed with that plugin. The same method called through `agent.ctx` contributes to one agent and is disposed with that agent's scope.
| Registration origin | Default visibility | Disposed with |
|---|---|---|
| Plain plugin context | Every eligible agent view | Registering plugin |
| `agent.ctx` | Exactly that agent's view | Agent scope |
Tools, prompt sections and variables, tool restrictions, guards, and scoped event listeners adopt this contract. Named local values ordinarily shadow a same-named global value for that agent; each owning service documents exceptions and merge behavior.
The ordinary contributor pattern is to register the complete local world during agent setup:
```js
const handle = await ctx.agents.create({
agentId: AgentId('reviewer'),
sessionId: SessionId('reviewer-session'),
agentOptions: { model: 'model-name' },
setup(agentCtx) {
agentCtx.systemPrompt.section({
name: 'deployment:persona',
order: 0,
text: 'Review code, but do not modify files.',
})
agentCtx.tools.register({
name: 'review_summary',
description: 'Return the review summary.',
parameters: { type: 'object', properties: {} },
async execute() {
return [{ type: 'text', text: 'review complete' }]
},
})
},
})
ctx.tools.get('review_summary') // undefined: not global
ctx.tools.get('review_summary', handle.agent) // the reviewer-local tool
await handle.dispose()
ctx.tools.get('review_summary', handle.agent) // undefined: scope is gone
```
Setup receives a full trusted Cordis context so it can compose ordinary plugins and services. Its contract is composition-only: driving or publishing the in-flight agent through casts or internal registry calls is unsupported.
### The operation chooses the view
Registration origin and operation subject are separate facts. Calling a service through `agent.ctx` selects where a new registration belongs; it does not bind later reads to that agent.
Tool lookup and execution receive the agent they act for. Prompt assembly receives an assembly context for the agent whose request is being built. Event dispatch receives its domain subject. This keeps shared service instances reusable across agents while making each operation's view explicit.
Only services that adopt the scope contract resolve an agent layer. `agent.ctx` does not automatically change arbitrary Cordis service calls.
### Scoped events keep routing separate from event data
An event about Agent A normally reaches unscoped listeners and A-scoped listeners, not B-scoped listeners. An event without an agent subject reaches only unscoped listeners.
At the Cordis level, `Scoped<T>` is an opaque routing receiver. It carries the filter used to choose listeners but is not the domain object. Event signatures therefore keep the real `Agent`, tool execution, approval request, or other subject as an explicit argument that listeners can inspect.
A listener registered with `{ global: true }` deliberately bypasses contextual audience filtering while its cleanup still follows the registering context. Registry-membership notifications remain unfiltered because they describe shared registry state rather than one agent's operation. The generated [event catalog](../../../cordis-catalog/events.md) is the exhaustive event reference.
### Creation publishes last and disposal revokes last
`ctx.agents.create()` and `resume()` build an unpublished session, scope, agent, and driver. They await `setup`, admit the final session and agent entries, announce them in order, start the loop, and only then return a handle.
An optional creation signal cancels work only while create or resume is pending. After the promise resolves, the returned `AgentHandle` owns explicit disposal.
If loading, setup, admission, or publication fails, the private transaction rolls back everything it prepared. Concurrent operations using the same caller-supplied live ID may both reach setup, but final registry entry admits only one; every loser rejects and cleans its private resources. Sequential reuse after awaited disposal remains valid.
`AgentHandle.dispose()` reverses the boundary. It deactivates creation or driving, waits for synchronous publication to unwind, stops and drains the driver and final session flushes, detaches the agent and session, and finally disposes the scope. Repeated or racing disposal requests join one completion promise.
The calling Cordis context and the concrete AgentLoop factory are structural co-owners. Unloading either disposes the transaction or live agent.
```mermaid
flowchart TB
request["Create or resume"] --> privateWorld["Build private session, scope, agent, and driver"]
privateWorld --> setup["Await composition through agent.ctx"]
setup --> admission["Admit final session and agent entries"]
admission --> publish["Announce lifecycle and start the driver"]
publish --> live["Return AgentHandle"]
privateWorld -->|"failure, cancellation, or owner loss"| rollback["Rollback private work"]
setup -->|"failure, cancellation, or owner loss"| rollback
admission -->|"duplicate or owner loss"| rollback
publish -->|"listener failure or owner loss"| rollback
live -->|"handle or owner disposal"| quiesce["Stop and drain work"]
rollback --> quiesce
quiesce --> detach["Detach agent, then session"]
detach --> revoke["Dispose the agent scope"]
```
## Security and authority are non-goals
Agent scopes compose trusted same-process registrations. They do not sandbox plugins, define a parent-to-child authority lattice, freeze grants at creation, or guarantee that a child can do no more than its parent.
A parent may own a child whose visible tools are wider than its own because lifetime ownership does not donate or cap registrations. A plugin holding a Cordis context also runs in the same process and can call available services directly.
Deployments that need non-escalation require a separate authority representation, propagation rule, and execution check. Parent-subset grants, creation-time authorization snapshots, explicit future-grant APIs, and generic capability/output/termination tags are outside this decision.
## Alternatives considered
The rejected designs either separate visibility from cleanup, cover only one registration family, duplicate shared infrastructure, or conflate lifetime ownership with inheritance.
### Pass an agent option to every registration
An API such as `tools.register(definition, { agent })` repeats scope plumbing in every registry and permits visibility ownership to drift from cleanup ownership. Registering through `agent.ctx` makes both facts follow one Cordis effect owner.
### Filter events while keeping registries global
Listener filtering prevents the wrong hook from running but does not scope tool schemas, executable lookup, prompt sections, variables, or other registered data. Agent-local composition would still require temporary global mutation.
### Create one service graph per agent
The required view is shared deployment services plus one local registration layer. Per-agent graphs duplicate adapters and complicate shared persistence, provider registries, and application boot.
### Inherit parent registration scopes
Parentage describes lifetime and conversation lineage, not a universal merge policy. Hierarchical lookup makes unrelated services inherit accidentally and cannot define security without a separate authority model.
## Consequences
Contributors use one familiar pattern: register shared behavior through a plugin context, register local behavior through `agent.ctx`, select the real agent on operations, and dispose the returned handle. Setup is atomic from an observer's perspective, and teardown preserves local behavior until work stops.
The cost is explicit subject selection, asynchronous programmatic creation, and service-specific scope adoption. Flat registration scope is intentionally not authority, and subagent composition controls remain a separate feature rather than hidden scope semantics.

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# RFC: Tool output spill policy
Status: implemented
## Problem
Tool outputs need bounded model-facing previews, but some oversized results are still useful later. A fetched page body or a verbose tool response should not consume the next model request in full, but the model should be able to inspect the complete formatted result later with existing file-reading tools.
Before this change the behavior was uneven. `dsh-bash-local` already writes complete stdout/stderr streams to private temp spill files when its in-memory tail overflows, but ordinary text tool results were returned inline unless the tool hand-rolled its own cap. The [tool result retention library](./2026-07-06-tool-result-retention-library.md) owns preview mechanics, but it does not own storage or an execution-pipeline policy that applies those mechanics to final tool results.
The shape matches the timeout policy design: a tool author normally returns the text result, and a policy plugin enforces the deployment's default context budget. Tool-specific early spill remains possible later for outputs that do not survive to the final `ToolExecutionResult`; the first cut proves the default final-result path.
## Decision
A thin spill storage seam plus a default spill policy plugin, in a new `packages/spill/` group:
| Package | Role |
|---|---|
| `@deepseek-ai/dsh-spill` | Interface: `ctx.spillStore`, vocabulary types, no storage implementation. |
| `@deepseek-ai/dsh-spill-local` | Local backend: private, session-scoped file storage on the host filesystem. |
| `@deepseek-ai/dsh-spill-policy` | Tool-result policy plugin: wraps final text results after dispatch and replaces oversized results with a retained preview plus a spill locator. |
There is no dedicated model-facing consumer package. The consumer is the existing `ctx.tools` execution pipeline: `dsh-spill-policy` consumes final tool results through the `tools/post-execute` waterfall, and the model follows the backend-supplied retrieval hint for the returned locator.
### Spill seam
The storage seam is minimal: save text and return a locator plus retrieval hint.
```ts ignore-check
interface SpillStore {
saveText(input: SaveTextSpill): Promise<SpillRef>
}
interface SpillSource {
toolName: string
callId: CallId
label: string
}
interface SaveTextSpill {
owner: { sessionId: SessionId }
source: SpillSource
suggestedName: string
content: string
}
type SpillLocator = Branded<'SpillLocator'>
interface SpillRef {
locator: SpillLocator
bytes: number
retrievalHint: string
}
```
`SpillLocator` is a [branded](../../../../packages/util/brand) model-facing handle returned by the backend. The local backend renders it as a filesystem path; a remote or database backend can render a URI, key, or command token. Consumers treat it as opaque and render it with `retrievalHint` instead of assuming `read` is always the right retrieval mechanism. `SpillOwner.sessionId` is the save-time storage namespace: forked sessions inherit existing spill locators from the seeded log without copying or re-owning them, and new spills after the fork use the child session id. A retention-period cleanup may expire old locators with other old session artifacts; the spill seam does not define a per-session cleanup policy.
`dsh-spill-local` owns only storage details: session-scoped directory selection, safe names, path-traversal protection, the write, and returning `{ locator, bytes, retrievalHint }`. It does not own retention policy, tool-result replacement, search, or file inspection. Files land at `<root>/session-<hash>/<random>-<safeName>`, where `root` is a configured path or a lazily-created private (0700) per-process temp dir, the session subdir is a short `sha256(sessionId)` prefix, and the leaf is a random hex prefix plus the caller's `suggestedName` sanitized to one path segment (mirrors the JSONL backend's `encodeSegment`). The write is `open(path, 'wx', 0o600)` — exclusive and owner-only, so a planted symlink cannot redirect it. The locator is the path, and the retrieval hint tells the model it can use `read` or `grep` on that path.
### Spill policy
`dsh-spill-policy` is a `tools/post-execute` result transformer with one configuration knob:
```ts ignore-check
interface Config {
/** Omitted means no automatic spill policy. Present means apply to oversized plain text tool results. */
maxInlineBytes?: number
}
```
When `maxInlineBytes` is omitted the plugin registers nothing (a true no-op). When set, it applies a default policy to final plain-text tool results:
1. Let the tool run normally, delegating via `next()` so a downstream listener settles the result first.
2. Flatten the accepted final `ContentBlock[]` only when it is entirely plain text; a result with any non-text block is left untouched.
3. If its UTF-8 byte size is at or below `maxInlineBytes`, leave it unchanged.
4. If it is larger, call `ctx.spillStore.saveText()` with the full final text.
5. Replace the model-facing result with a retained head/tail preview plus the spill reference.
The preview is an implementation default owned by the policy: a head/tail split of `maxInlineBytes` via the retention library's `TextRetainer`. Future config can expose preview sizing only after a second deployment needs it.
The replacement text is intentionally generic because the policy only knows the final formatted tool result, not the tool's internal resource:
```text
<retained preview>
(Omitted N bytes. Full formatted result stored at: /.../session-.../....txt. Use read with offset/limit, or grep this path to search within it.)
```
If `ctx.spillStore.saveText()` fails (permissions, ENOSPC, backend unavailable), or the call has no session owner, or no backend is loaded, the plugin logs the reason and returns the original result unchanged. Spill failure never turns a successful tool call into an `isError` result or hides the inline result.
The policy skips `read` to avoid a circular `read -> spill file -> read again` loop. Additional opt-out configuration is deferred until a real second tool needs it.
## Showcase: web_fetch
`web_fetch` is the first showcase because it returns a naturally large text result and needs no tool-specific spill code. The tool is ordinary:
```ts ignore-check
ctx.tools.register(defineTool({
name: 'web_fetch',
async execute(args, exec) {
const result = await ctx.web.fetch({ url: args.url }, exec.signal ? { signal: exec.signal } : undefined)
return [{ type: 'text', text: formatFetchOutput(result) }]
},
}))
```
With `dsh-spill-policy` configured, a large formatted fetch result is automatically retained and spilled. A deployment demonstrates the behavior by setting the provider resource cap higher than the policy cap:
```yaml
- id: web-fetch-local
name: '@deepseek-ai/dsh-web-fetch-local'
config:
maxBodyChars: 500000
- id: spill-local
name: '@deepseek-ai/dsh-spill-local'
- id: spill-policy
name: '@deepseek-ai/dsh-spill-policy'
config:
maxInlineBytes: 50000
```
This separation is important. `web-fetch-local` still owns resource caps (`maxResponseBytes`, `maxBodyChars`) to protect network, memory, and decoding work. `spill-policy` owns only the model-facing context cap after the result already exists. If the provider already returned `truncated: true`, the spill file contains the full formatted result the tool returned, not the full original webpage; the policy does not claim otherwise.
## Relationship to retention and early spill
Retention is separate from spill storage:
- `@deepseek-ai/dsh-retention` owns preview mechanics (`TextRetainer`, `ItemRetainer`, and omitted metadata).
- `@deepseek-ai/dsh-spill` owns saving final text and returning a locator plus retrieval hint.
- `@deepseek-ai/dsh-spill-policy` applies the default final-result policy in the tool pipeline, composing the two.
The final-result policy cannot replace tool-owned early spill. Some useful content is not present in final `ToolExecutionResult.content`:
- `bash` final output is already a tail plus a temp spill path; the complete stdout/stderr streams live in executor files.
- `subagent` final output is the child final answer, not the child rollout.
- Future tools may produce runtime artifacts that are never represented by their final `ToolExecutionResult.content`.
Those cases can consume `ctx.spillStore` directly in later work. They are not part of the first showcase.
## Non-goals
- No new model-facing `artifact_read` or `artifact_search` tool in v1.
- No per-tool retention configuration in v1.
- No model-facing timeout/truncation arguments.
- No migration of `read` output into spill files.
- No replacement for provider/resource caps such as `web-fetch-local.maxBodyChars`.
- No bash temp-file normalization or subagent rollout capture in the first cut.
## Deferred
- `saveFile()` / `linkOrCopy` for existing executor spill files, needed for bash normalization.
- Tool-owned spill for subagent rollouts (`await run.result`, read in-process child session before `run.dispose()`, save JSONL).
- Per-tool opt-out or per-tool policy declarations if the built-in `read` skip is insufficient.
- Remote or database storage backends for ACP or remote environments where a local path is not meaningful.
- Cleanup and retention policy for old spill files, likely tied to session cleanup.
## Testing
- `dsh-spill` unit tests pin the seam contract: registration as `ctx.spillStore`, one-implementation-per-context, and disposal release.
- `dsh-spill-local` unit tests cover `saveText`, `encodeSegment` sanitization (separators/tilde/whole-segment dots/empty), the session-hash directory, owner-only permissions, distinct paths per save, the configured/private root, and a storage-failure rejection.
- `dsh-spill-policy` unit tests drive real tools through `ctx.tools.execute`: disabled-mode no-op, oversized-text replacement, small/non-text passthrough, `read` skip, best-effort fallback (save failure / no backend / no owner), and downstream-composition (bounding a replaced result, preserving `additionalContexts`).
- `dsh-tool-web` integration drives `web_fetch` through `ctx.tools.execute` with the real `spill-local` backend + policy, proving the model-facing text changes only by the deliberate spill notice while the spill file holds the full formatted result.
- The `coding-agent` example loads `spill-local` + `spill-policy`, so its keyless Loader smoke exercises the real load path (the namespace-plugin export shape + `inject`).
## Consequences
The default policy only sees final formatted text. It cannot preserve provider-internal content that was already capped or runtime artifacts that were never part of the result. This is acceptable for the first cut because the showcase is final-result spill, not early spill; tool-owned early spill remains deferred work.
Returning real paths from the local backend keeps v1 simple and matches proven agent-tool behavior, while the seam itself only promises an opaque locator plus retrieval hint so remote backends can return non-file locators.
The local-backend value proposition depends on the existing `read`/`grep` tools being able to inspect the returned local path, even when the spill directory is outside the session cwd. That holds today because the filesystem policy records observations and write guards but does not confine reads to the workspace. A future workspace-confinement policy must either allow local spill paths explicitly or use a non-file spill backend whose retrieval hint points at a supported reader.
**Snapshot gap.** No ACP snapshot scenario covers the transcript-visible `web_fetch` spill notice yet. The ACP snapshot harness replays keyless and cannot hit the live web, and a `web_fetch` spill requires a real over-cap HTTP body; a deterministic scenario would need a seeded loopback fetch target the replay tree does not currently wire (the examples do not load `tool-web` at all). The behavior is covered instead by the `dsh-tool-web` integration test against a loopback server. Closing the gap is follow-up work: wire `tool-web` + a seeded fetch target into the ACP example, then record a `web-fetch-spill` scenario.
The policy can become too large if it starts owning tool-specific semantics. It stays narrow: plain-text final results only. Tool-owned early spill remains future work.
## Alternatives considered
**Require each tool to opt in with a retention declaration.** Rejected for v1: the goal is a default behavior similar to Claude Code's generic tool-result persistence. A single `maxInlineBytes` deployment knob is enough to prove the shape.
**Make `tool-results` a broad tool-result platform.** Rejected: a broad package name invites retention policy, result replacement, preview wording, search, and early spill into one seam. The shared storage part is smaller: save text and return a locator plus retrieval hint.
**Use `ctx.fs.writeText` or the model-facing `write` tool.** Rejected: workspace filesystem writes carry project-file semantics, write/edit policy, observation state, and user-facing side effects. Spill files are runtime artifacts, not model-authored workspace edits. The existing `read` tool may inspect them later, but creation belongs to the runtime spill seam.
**Let `web-fetch-local` fetch without caps and rely on spill-policy.** Rejected: spill-policy runs after the final tool result exists and cannot protect network, memory, or decoding resources. Provider resource caps stay mandatory.
**Merge retention into spill.** Rejected: retention and spill have different responsibilities. `TextRetainer`/`ItemRetainer` decide what preview is kept and what was omitted; spill storage only saves the final text the policy asks it to save.

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# Bilingual-pair consistency record (docs/i18n/README.md): the git blob hash of each
# side as of the last confirmed-consistent state. Both languages carry equal authority;
# after editing either side, bring the other along and re-record with:
# pnpm run verify-translation-pairing --write
2026-07-10-single-file-executable-sdk-runtime-distribution.md: b177af24e988c6a314db522b8de0d1c09e30464f
2026-07-10-single-file-executable-sdk-runtime-distribution.zh.md: 0b964e8a748e4adcc32c017957e5294a3f258365

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# RFC: Single-file executable SDK runtime distribution (single-exe)
Status: implemented
English | [中文](2026-07-10-single-file-executable-sdk-runtime-distribution.zh.md)
## Problem
DeepSeek Harness needs a dedicated SDK distribution form for the Python library — no Node installation, runs directly on the target platform: a single-file executable (hereafter "the exe") that exposes a stdio JSON-RPC serving surface (`HarnessSdkServer`, the Python SDK's peer), where the plugins and configuration actually booted are decided entirely by a `cordis.yml` supplied from outside the exe.
- The JSONRPC protocol for talking to the Python SDK is already validated
- A standardized way for cordis.yml to load every plugin (ESModule) is needed
- The distribution must carry the Node runtime, and support a locally linked source debugging mode
## Decision
### Packaging route: @yao-pkg/pkg's `--sea` mode
The exe is packaged with the **`--sea` (enhanced SEA) mode** of [@yao-pkg/pkg](https://github.com/yao-pkg/pkg) (the actively maintained fork after vercel/pkg was archived). Relative to Node's native SEA, pkg adds a `/snapshot` VFS and runtime module hooks on top, hands the ESM entry to Node's default ESM loader unchanged, and depends on no ESM→CJS transpilation.
> Measured (macos-arm64, node24 target, pkg 6.21.0): bare-specifier ESM dynamic import inside the VFS (including top-level await), CJS interop, `node:sqlite`, fail-loud on package names outside the set, and on-disk ESM import outside the VFS all pass; `import.meta.url` comes through unchanged as `file:///snapshot/...`.
`--sea` requires target ≥ node22; the exe uniformly targets node24. One pkg invocation packages exactly one target; multi-platform builds invoke it once per platform.
Terminology reminder: pkg's `/snapshot` VFS has nothing to do with this repo's testing-system "snapshot" (ACP replay goldens, `$DSH_SNAPSHOT`); this document says "VFS" for the former.
### The serving surface is a plugin: the two packages ui/jsonrpc + examples/jsonrpc-demo
The deterministic protocol implementation (`server.ts` / `transport.ts`) lands as two packages on the existing `ui/acp` + `examples/acp-demo` pattern — the serving surface is itself a plugin:
- [`packages/ui/jsonrpc`](../../../../packages/ui/jsonrpc/README.md) (`@deepseek-ai/dsh-jsonrpc`): the pure protocol plugin; on apply it mounts `HarnessSdkServer` plus a line-delimited JSON-RPC transport on the process stdio, with disposal through `ctx.effect()`. Whether to serve is decided by `cordis.yml`; a yml that does not mount it is a legitimate process that does not serve. Protocol-level exit belongs to the plugin (after answering the `shutdown` request it disposes its own fiber, then `exit(0)`; an HMR-style unload only stops the service without exiting the process).
- [`packages/examples/jsonrpc-demo`](../../../../packages/examples/jsonrpc-demo/README.md) (`@deepseek-ai/dsh-jsonrpc-demo`): a thin app bin — `installFailLoud` + `loadEnv` + config discovery + `boot()` from [`dsh-app-boot`](../../../../packages/ui/app-boot/src/index.ts), done once boot completes; the server is brought up by the `dsh-jsonrpc` entry in the yml. Its only dependency is app-boot. Process-level exit belongs to the bin (stdin EOF/SIGTERM → dispose then 0, SIGINT → 130).
Config discovery has two channels and fails loudly when both are missing: the `DSH_CORDIS_CONFIG` environment variable first (the SDK client convention), then an argv positional argument; no default path and no built-in fallback whatsoever — "the plugins actually booted are decided by an external cordis.yml" is a hard semantic.
### Plugin resolution: the VFS holds a real package tree, the closure manifest IS the deploy root
Inside the exe's VFS sits a **real package tree in build-artifact form** (each package's `lib/` plus a real `node_modules`); the Loader resolves plugin names through standard dynamic `import()`: bare specifiers resolve upward along `node_modules` from the Loader's position inside the VFS, and land inside the VFS naturally. The closed set needs no allowlist code — the set is whatever the VFS has installed, and importing a name outside the set fails.
The deploy root is [`python/sdk-runtime/package.json`](../../../../python/sdk-runtime/package.json) (`dsh-jsonrpc-agent-pkg`, a pnpm workspace member and a zero-code pure dependency manifest) — the unified source of truth for "which plugins the exe ships" and "what the Python runtime distributes". Adding a plugin to the exe = adding one dependency line to the manifest and repackaging. [`scripts/verify-runtime-closure.ts`](../../../../scripts/verify-runtime-closure.ts) traverses every workspace package covered by that manifest and requires every non-optional workspace peer at the runtime root, reporting the complete referencing-package → missing-peer chain; CI static, pre-push, and the single-exe build run it before packaging. Deploy also packs by each package's `files`, so the shared chunks tsdown splits out must be covered by `files`.
### Build pipeline and artifacts
[`scripts/build-exe-for-python-sdk.ts`](../../../../scripts/build-exe-for-python-sdk.ts): runtime closure verification → `pnpm run build` → (after clearing) `pnpm --filter dsh-jsonrpc-agent-pkg deploy --legacy --prod --config.node-linker=hoisted --config.auto-install-peers=false --config.link-workspace-packages=true` **directly into** `python/sdk-runtime/src/deepseek_harness_runtime/runtime/node/` → inject the pkg configuration (`bin` points at `node_modules/@deepseek-ai/dsh-jsonrpc-demo/lib/bin.js` inside the closure, `assets` is a full glob — dynamic import is invisible to pkg's static analysis, so everything must be packed in explicitly) → one `pkg --sea` per target → the executables `dsh-jsonrpc-agent-pkg-<platform>-<arch>` land in `dist-exe/` and are copied back into the runtime directory. CI treats them as intermediate test inputs and retains their platform wheels. All four deploy flags are grounded in measurement: `--legacy` is the mandatory path with inject-workspace-packages off; hoisted yields a zero-symlink file tree (most stable for the pkg VFS, physically guaranteeing a single cordis instance); disabling automatic peer installation keeps unpublished package names from triggering registry resolution; link-workspace-packages points the closure at workspace/vendor sources.
CI: [`.github/workflows/build-exe-for-python-sdk.yml`](../../../../.github/workflows/build-exe-for-python-sdk.yml), triggered explicitly only — `workflow_dispatch`, or the `build-exe` label on a pull request; native builds on the three platforms linux-x64 / linux-arm64 (`ubuntu-24.04-arm`) / macos-arm64, with `~/.pkg-cache` cached; macOS ad-hoc signing is handled by pkg. Each leg drives a mock SSE model through the SDK with the default config and a custom `cordis.yml`, drives the exe directly over NDJSON JSON-RPC, verifies the JSONL and final response, and installs release-shaped wheels into a clean venv without `runtime_bin`; Linux additionally inspects GLIBC requirements and runs in a manylinux 2.28 container. A full three-target run retains four artifacts, each containing one release file: the platform-independent SDK wheel and three native runtime wheels; a subset dispatch retains the SDK wheel and selected runtime wheels. Bare executables and source bundles remain intermediate test inputs. [`.gitlab-ci.yml`](../../../../.gitlab-ci.yml) accepts only `python-vX.Y.Z` tag pipelines whose version matches the root `package.json`, builds one SDK wheel and three native runtime wheels, then a single serialized job checks and publishes all four to the project PyPI registry. Windows is a non-goal.
### Python SDK distribution: two carriers, exe for production, node for development
The Python SDK lives at [`python/`](../../../../python/README.md): `python/sdk` (the client) + `python/sdk-runtime` (the runtime carrier package). The runtime package's data directory holds three kinds of content: the checked-in default `runtime/cordis.yml`, the build-injected platform exe, and the build-injected `runtime/node/` closure tree. `resolve_bundled_launch_args()` automatic resolution **finds the exe only**; the node carrier is enabled only by an explicit `DSH_RUNTIME_MODE=node` (running `runtime/node/node_modules/@deepseek-ai/dsh-jsonrpc-demo/lib/bin.js`, requiring a system node ≥22.19), positioned as the development-verification channel for members of this repo, and does not enter wheel distributions.
[`scripts/build-python-release.py`](../../../../scripts/build-python-release.py) reads the authoritative stable `X.Y.Z` from the repository root `package.json` and stages both packages at that version, with the SDK depending exactly on `deepseek-harness-runtime-bin==X.Y.Z`. An optional `python-vX.Y.Z` release tag is a consistency assertion and is rejected when it differs from the repository version; the source `pyproject.toml` development sentinel never determines a release version. The SDK is a `py3-none-any` wheel; the wheel-only runtime package contains exactly one exe and uses one of `py3-none-manylinux_2_28_x86_64`, `py3-none-manylinux_2_28_aarch64`, or `py3-none-macosx_11_0_arm64`. Its Hatch hook rejects sdists, universal tags, mixed executable payloads, and unsupported platforms.
The exe's "must be explicitly configured" hard semantic is unchanged; the zero-config experience is restored by the wrapper: when the caller gave no `cordis`, named no explicit runtime, and the environment has no `DSH_CORDIS_CONFIG`, the client explicitly injects the checked-in default `cordis.yml` (agent-core + preloaded llm-deepseek + JSONL persistence + bash-local + the `dsh-jsonrpc` serving entry, with `!!js` environment-variable fallbacks) via `DSH_CORDIS_CONFIG`.
### Naming lineage
`@deepseek-ai/dsh-jsonrpc-demo` (the package) → `dsh-jsonrpc-agent` (the bin) → `dsh-jsonrpc-agent-pkg` (the closure manifest; no scope prefix, deliberately sidestepping the constraints' package-shape rules for `@deepseek-ai/dsh-*`) → `dsh-jsonrpc-agent-pkg-<platform>-<arch>` (the exe artifacts). The wire `serverInfo.name` stays `deepseek-harness-sdk-runtime` (a protocol-stable value); the Python dist names are `deepseek-harness` / `deepseek-harness-runtime-bin`.
## Disposition of worker-style plugins
`dsh-workflow-workerthread` and `dsh-code-runtime-worker` are supported inside the exe. Their built hosts convert the sibling `lib/worker.cjs` URL with `fileURLToPath()` and pass the resulting filesystem string to `Worker`, which is the form pkg's Worker hook resolves inside the VFS. The worker entries are CommonJS because that hook compiles VFS worker files as CommonJS. The workflow engine keeps its data-URL bootstrap for unbuilt source execution; only its built sibling entry uses the filesystem string. The custom-config executable smoke loads both backends, invokes a real `run_code` call and a zero-agent `workflow` call, and requires each worker to return `42` from inside pkg's VFS.
## Testing
The verification surface has three tiers. Mechanism tier: the measured conclusions for the `--sea` chain are embedded in the Decision sections (ESM dynamic import inside the VFS, single cordis instance, fail-loud config chain, `node:sqlite`, macOS ad-hoc signing runs). SDK tier: the complete keyless pytest suite covers the client protocol against a fake runtime peer, subprocess cleanup, absolute cwd propagation, dual-carrier launch, and carrier resolution; root CI runs it on Python 3.10. End-to-end tier: every platform build completes a turn against a mock endpoint through the default SDK path, a custom config, and the direct binary protocol, with final text and JSONL checked. The custom config additionally drives `run_code` and a zero-agent `workflow` through their real worker files inside the packaged VFS. The same build leg runs a committed executable-specific snapshot through the Python SDK: a keyless scripted model mounts a Cordis plugin that registers a tool, invokes that tool from `run_code`, runs a direct spawn subagent and a workflow that starts a second spawn child, then unmounts the plugin. The comparison normalizes the SDK result and notification stream plus the parent and two child JSONL logs. This harness stays separate from ACP's `pnpm run test:snapshot` because the protocols and build artifacts differ. The platform wheel is then installed in a clean venv and run without `runtime_bin`.
Manual-driving caveat: the bin treats stdin EOF as "the client is gone" and disposes immediately, so a short-lived pipe aborts an in-flight turn — pipe-driven runs must keep stdin open until the turn ends.
## Alternatives considered
**Bare Node native SEA.** The injected main script must be a single CJS file, and the blob carries no filesystem and no module resolution, so a dynamic import of a bare specifier has nothing to resolve against; the only option is compiling plugins statically into the main script and registering them by hand — bypassing standard module resolution and hardcoding the plugin set, contrary to "configuration decides everything". The final route is in fact "the official SEA foundation + pkg's VFS/module-hook layer"; what was rejected is the bare use, not SEA itself.
**pkg standard mode.** Killed by the PoC, not a trade-off: it turns ESM into CJS + V8 bytecode via esbuild, the runtime vm compilation wires up no dynamic-import callback, every `import()` throws `ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING`, and `--options experimental-require-module` has no effect; it also depends on community-patched Node binaries (no macos-arm64 prebuilt; compiling from source on the spot takes about 10 minutes). Zero viability for this repo's architecture.
**Pre-bundling each package ESM→CJS into the VFS.** The compromise that keeps real resolution semantics and only downgrades the module format; `--sea` passed measurement outright, so this layer of build complexity never needed introducing.
**jsonrpc-agent carrying the full closure dependencies.** The app bin would declare 53+ dependencies it never imports — a "packaging manifest" masquerading as real dependency relationships — and would force constraints to open two exceptions for it, cordis-in-dependencies and a files wildcard. With the closure manifest landing on the python-side manifest package, constraints needs no exception at all and the bin keeps the normal package shape isomorphic to acp-agent.
**An open plugin set (loading user plugins from disk).** This round ships a closed set; the PoC incidentally confirmed that on-disk ESM import outside the VFS works (through the `ctx.baseUrl` relative-path channel). It is listed as a future evolution, which must separately solve sharing the cordis instance inside the exe with external plugins.
## Consequences
**Bought**: zero-dependency single-file distribution on target platforms; plugin semantics strictly identical to running from source (the same real package tree, no transpilation, no registry); the serving surface, the plugin set, and the configuration all converge on two sources of truth — `cordis.yml` plus one dependency manifest; the exe and node carriers share one tree and one semantics, so development verification never waits for packaging; official Node binaries remove the patched-binary supply-chain concern.
**Paid**: artifacts on the order of 174MB with source entering the blob as-is (no bytecode obfuscation; a closed-source distribution requirement needs a separate evaluation); pkg's VFS/module-hook layer remains community-maintained (the build script pins `@yao-pkg/pkg@6.21.0`; upgrading is an explicit change); `--sea` is one invocation per target (matching CI's one leg per platform; local multi-platform builds are serial).

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# RFC: 单文件可执行的 SDK 运行时分发single-exe
Status: implemented
[English](2026-07-10-single-file-executable-sdk-runtime-distribution.md) | 中文
## 问题
DeepSeek Harness 需要为 Python 库专门提供一种无需安装 Node、可直接在目标平台运行的 SDK 分发形态:一个单文件可执行程序(下称 exe通过 stdio 提供 JSON-RPC 对外服务接口(`HarnessSdkServer`Python SDK 的对端),且实际启动的插件与配置完全由 exe 外部输入的 `cordis.yml` 决定。
- 与 Python SDK 通信的 JSON-RPC 协议已经过验证
- 需要提供通过标准化 `cordis.yml` 加载所有插件ES 模块)的能力
- 分发物要自带 Node 运行时,并支持本地源码链接的调试模式
## 决策
### 打包路线:@yao-pkg/pkg 的 `--sea` 模式
exe 使用 [@yao-pkg/pkg](https://github.com/yao-pkg/pkg)vercel/pkg 归档后的活跃维护 fork**`--sea`enhanced SEA模式**打包。相比 Node 原生 SEApkg 在其上增加 `/snapshot` 虚拟文件系统VFS与运行时模块钩子将 ESM 入口原样交给 Node 默认的 ESM loader不依赖任何 ESM→CJS 转译。
> 实测macos-arm64、node24 构建目标、pkg 6.21.0VFS 内裸包名 ESM 动态 `import()`(含顶层 `await`、CJS 互操作、`node:sqlite`、集合外包名明确报错、VFS 外磁盘 ESM `import()` 全部通过,`import.meta.url` 原样为 `file:///snapshot/...`。
`--sea` 要求构建目标 ≥ node22exe 统一以 node24 为构建目标;每次 pkg 调用只打包一个构建目标,多平台各调用一次。
术语提醒pkg 的 `/snapshot` VFS 与本仓库测试体系的“快照”ACP 回放 golden、`$DSH_SNAPSHOT`无关本文用“VFS”指前者。
### 对外服务接口也是插件ui/jsonrpc + examples/jsonrpc-demo 两包
确定性协议实现(`server.ts` / `transport.ts`)按 `ui/acp` + `examples/acp-demo` 的既有模式落为两包——对外服务接口本身也是插件:
- [`packages/ui/jsonrpc`](../../../../packages/ui/jsonrpc/README.md)`@deepseek-ai/dsh-jsonrpc`):纯协议插件;执行 `apply` 时,在进程 stdio 上挂载 `HarnessSdkServer` 与按行传输的 JSON-RPC 层,资源释放走 `ctx.effect()`。是否提供服务由 `cordis.yml` 决定;未挂载该插件的配置会启动一个不提供此服务的合法进程。协议级退出归插件所有(应答 `shutdown` 请求后 dispose 自身 fiber再调用 `exit(0)`HMR 式卸载只停止服务,不退出进程)。
- [`packages/examples/jsonrpc-demo`](../../../../packages/examples/jsonrpc-demo/README.md)`@deepseek-ai/dsh-jsonrpc-demo`):轻量应用入口——`installFailLoud` + `loadEnv` + 配置发现 + [`dsh-app-boot`](../../../../packages/ui/app-boot/src/index.ts) 的 `boot()``boot()` 完成后入口即完成,服务器由 `cordis.yml` 中的 `dsh-jsonrpc` 条目启动。它只依赖 `app-boot`。进程级退出归 `bin` 所有stdin EOF/SIGTERM → dispose 后返回 0SIGINT → 130
配置发现有两个通道,均缺失时立即报错:优先使用 `DSH_CORDIS_CONFIG` 环境变量SDK 客户端约定),其次使用 argv 位置参数;没有默认路径或内置回退——“实际启动的插件由外部 `cordis.yml` 决定”是硬语义。
### 插件解析VFS 装载真实包树,闭包清单就是部署根目录
exe 的 VFS 内是**构建产物形态的真实包树**(各包的 `lib/` + 真实 `node_modules`。loader 通过标准动态 `import()` 解析插件名:裸包名从 VFS 内 loader 所在位置沿 `node_modules` 向上解析,自然落在 VFS 内。封闭集不需要白名单代码——VFS 中安装了什么,集合中就有什么;`import()` 集合外的名称会失败。
部署根目录是 [`python/sdk-runtime/package.json`](../../../../python/sdk-runtime/package.json)`dsh-jsonrpc-agent-pkg`pnpm 工作区成员、零代码纯依赖清单也是“exe 安装哪些插件”与“Python 运行时分发什么”的统一事实源。向 exe 添加插件,就是在清单中增加一行依赖后重新打包。[`scripts/verify-runtime-closure.ts`](../../../../scripts/verify-runtime-closure.ts) 遍历该清单覆盖的全部工作区包要求每个非可选的工作区对等依赖peer dependency都显式列在运行时根目录并报告“引用包 → 缺失对等依赖”的完整链路CI 静态检查、pre-push 与 single-exe 构建都会在打包前运行该门禁。部署还会依据各包的 `files` 字段打包,因此 tsdown 拆出的共享分片必须被 `files` 覆盖。
### 构建管线与产物
[`scripts/build-exe-for-python-sdk.ts`](../../../../scripts/build-exe-for-python-sdk.ts):运行时闭包校验 → `pnpm run build` →(清空后)`pnpm --filter dsh-jsonrpc-agent-pkg deploy --legacy --prod --config.node-linker=hoisted --config.auto-install-peers=false --config.link-workspace-packages=true` **直接写入** `python/sdk-runtime/src/deepseek_harness_runtime/runtime/node/` → 注入 pkg 配置(`bin` 指向闭包内的 `node_modules/@deepseek-ai/dsh-jsonrpc-demo/lib/bin.js``assets` 使用全量 glob因为动态 `import()` 对 pkg 静态分析不可见,必须显式打入全部内容)→ 每个构建目标调用一次 `pkg --sea` → 可执行文件 `dsh-jsonrpc-agent-pkg-<platform>-<arch>` 写入 `dist-exe/`并拷回运行时目录。CI 将这些文件作为测试中间输入,只保留对应平台的 wheel 包。四个部署标志都有实测依据:未启用 `inject-workspace-packages` 时必须使用 `--legacy``hoisted` 产出无符号链接的文件树(对 pkg VFS 最稳定,并从物理上保证只有一个 Cordis 实例);关闭对等依赖自动安装可避免未发布包名触发注册表解析;`link-workspace-packages` 让闭包指向工作区/vendor 源码。
CI 使用 [`.github/workflows/build-exe-for-python-sdk.yml`](../../../../.github/workflows/build-exe-for-python-sdk.yml),且只允许显式触发:手动派发 `workflow_dispatch`,或给 PR 添加 `build-exe` 标签。linux-x64、linux-arm64`ubuntu-24.04-arm`)和 macos-arm64 三个平台分别进行原生构建,并缓存 `~/.pkg-cache`macOS 的 ad-hoc 签名由 pkg 处理。每个平台都使用模拟 SSE 模型,分别通过默认配置和自定义 `cordis.yml` 驱动 SDK再通过 NDJSON JSON-RPC 直接驱动 exe校验 JSONL 与最终响应;最后把发布形态的 wheel 包安装到干净的 venv 中,并在不传 `runtime_bin` 的情况下运行。Linux 还会检查 GLIBC 依赖,并在 manylinux 2.28 容器中运行。完整构建三个目标时保留 4 个产物,每个产物只含一个发布文件:平台无关的 SDK wheel 包与 3 个原生运行时 wheel 包;手动选择部分目标时保留 SDK wheel 与所选运行时 wheel。裸 exe 与源码包只作为测试中间输入。[`.gitlab-ci.yml`](../../../../.gitlab-ci.yml) 只接受版本与根目录 `package.json` 匹配的 `python-vX.Y.Z` 标签流水线,构建一个 SDK wheel 包和 3 个原生运行时 wheel 包,再由单个串行任务校验并将这 4 个文件发布到项目的 PyPI 注册表。Windows 不在目标范围内。
### Python SDK 分发双载体exe 用于生产,`node` 用于开发
Python SDK 位于 [`python/`](../../../../python/README.md)`python/sdk` 是客户端,`python/sdk-runtime` 是运行时载体包。运行时包的数据目录包含三类内容:检入的默认 `runtime/cordis.yml`、构建注入的平台 exe以及构建注入的 `runtime/node/` 闭包树。`resolve_bundled_launch_args()` 的自动解析**只查找 exe**`node` 载体仅在显式设置 `DSH_RUNTIME_MODE=node` 时启用(运行 `runtime/node/node_modules/@deepseek-ai/dsh-jsonrpc-demo/lib/bin.js`,需要系统 Node ≥22.19),定位为本仓库成员的开发验证通道,不随 wheel 包分发。
[`scripts/build-python-release.py`](../../../../scripts/build-python-release.py) 从仓库根目录的 `package.json` 读取权威的稳定版本 `X.Y.Z`,以该版本暂存两个包,并让 SDK 精确依赖 `deepseek-harness-runtime-bin==X.Y.Z`。可选的 `python-vX.Y.Z` 发布标签只是一项一致性断言,与仓库版本不同时会被拒绝;源码 `pyproject.toml` 中的开发占位版本从不决定发布版本。SDK 是 `py3-none-any` wheel 包;只提供 wheel 包的运行时包恰好包含一个 exe标签为 `py3-none-manylinux_2_28_x86_64``py3-none-manylinux_2_28_aarch64``py3-none-macosx_11_0_arm64`。其 Hatch 钩子拒绝 sdist、通用标签、混合可执行载荷以及不支持的平台。
exe“必须显式配置”的硬语义不变零配置体验由包装层恢复调用方没有提供 `cordis`、没有显式指定运行时,且环境中没有 `DSH_CORDIS_CONFIG` 时,客户端将检入的默认 `cordis.yml``agent-core` + 预载的 `llm-deepseek` + JSONL 持久化 + `bash-local` + `dsh-jsonrpc` 对外服务条目,并通过 `!!js` 使用环境变量兜底)显式注入 `DSH_CORDIS_CONFIG`
### 命名血统
`@deepseek-ai/dsh-jsonrpc-demo`(包)→ `dsh-jsonrpc-agent``bin`)→ `dsh-jsonrpc-agent-pkg`(闭包清单;没有作用域前缀,刻意避开 `constraints``@deepseek-ai/dsh-*` 的包形状规则)→ `dsh-jsonrpc-agent-pkg-<platform>-<arch>`exe 产物)。协议字段 `serverInfo.name` 保持为 `deepseek-harness-sdk-runtime`协议稳定值Python 分发名为 `deepseek-harness` / `deepseek-harness-runtime-bin`
## 工作线程插件
exe 内支持 `dsh-workflow-workerthread``dsh-code-runtime-worker`。两个后端构建后的宿主都通过 `fileURLToPath()` 转换相邻 `lib/worker.cjs` 的 URL再将所得文件系统字符串传给 `Worker`pkg 的 Worker 钩子可以用这种形式解析 VFS 内文件。该钩子会把 VFS 内的工作线程文件作为 CommonJS 编译,所以工作线程入口采用 CommonJS。工作流引擎在未构建的源码执行中仍保留 `data:` URL 引导程序,只有构建后的相邻入口使用文件系统字符串。自定义配置的可执行文件冒烟测试会加载两个后端,实际调用 `run_code` 与不启动 agent 的 `workflow`,并要求两个工作线程都从 pkg 的 VFS 内返回 `42`
## 测试
验证面分三层。机制层:`--sea` 链路的实测结论内嵌在“决策”各节VFS 内 ESM 动态 `import()`、单一 Cordis 实例、明确报错的配置链路、`node:sqlite`、macOS ad-hoc 签名可运行。SDK 层:完整的无密钥 pytest 套件以假运行时对端覆盖客户端协议、子进程清理、绝对 `cwd` 传递、双载体启动与载体解析;根 CI 在 Python 3.10 上运行全部用例。端到端层:每个平台构建都通过默认 SDK 路径、自定义配置和直接二进制协议,对模拟端点完成一个轮次,并校验最终文本与 JSONL。自定义配置还会通过打包进 VFS 的真实工作线程文件执行 `run_code` 和不启动 agent 的 `workflow`。同一构建任务还会经 Python SDK 运行一组检入的 exe 专用快照:无密钥脚本化模型挂载一个会注册工具的 Cordis 插件,从 `run_code` 调用该工具,运行一个由 spawn 提供方直接启动的 subagent子 agent和一个会通过 spawn 启动第二个子 agent 的工作流,随后卸载该插件。比较时会规范化 SDK 结果与通知流,以及父会话和两个子会话的 JSONL 日志。该 harness 与 ACP 的 `pnpm run test:snapshot` 保持独立,因为二者的协议和构建产物不同。随后把平台 wheel 包安装进干净的 venv并在不传 `runtime_bin` 的情况下运行。
手工驱动注意:`bin` 将 stdin EOF 视为“客户端已离开”并立即 dispose短命管道会中止进行中的轮次——管道驱动必须保持 stdin 打开,直到轮次结束。
## 曾考虑的替代方案
**裸用 Node 原生 SEA。** 注入的主脚本必须是 CJS 单文件blob 内没有文件系统与模块解析,因此动态 `import()` 无法解析裸包名;只能把插件静态编译进主脚本并手工注册。这会绕过标准模块解析并硬编码插件集合,与“配置决定一切”相悖。最终路线实际是“官方 SEA 基础 + pkg 的 VFS/模块钩子层”;否决的是裸用方式,而不是 SEA 本身。
**pkg 标准模式。** PoC 证明该模式不可行,而非权衡后放弃:它通过 esbuild 将 ESM 转为 CJS + V8 字节码,但运行时 VM 编译没有接入动态 `import()` 回调,任何 `import()` 都会抛出 `ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING``--options experimental-require-module` 也无效;此外,它依赖社区补丁版 Node 二进制macos-arm64 没有预编译版本,现场从源码编译约需 10 分钟)。该模式不适用于本仓库架构。
**每包 ESM→CJS 预打包进 VFS。** 保持真实解析语义、只降级模块格式的折中;`--sea` 直接通过实测,这层构建复杂度无需引入。
**让 jsonrpc-agent 承担完整闭包依赖。** 应用入口将声明 53 个以上自身并不 `import()` 的依赖,使“打包清单”伪装成真实依赖关系,还会迫使 `constraints` 为其增加 `cordis-in-dependencies``files` 通配符两个例外。将闭包清单放在 Python 侧的清单包后,`constraints` 不需要任何例外,`bin` 也能保持与 acp-agent 同构的正常包形状。
**开放插件集(从磁盘加载用户插件)。** 本期采用封闭集PoC 同时证实,可以通过 `ctx.baseUrl` 相对路径通道从 VFS 外的磁盘 `import()` ESM。该能力列为后续演进届时还需解决外部插件与 exe 内 Cordis 实例的共享问题。
## 后果
**买到的**:目标平台零依赖的单文件分发;插件语义与源码运行严格一致(同一棵真实包树,无转译、无注册表);对外服务接口、插件集与配置全部收敛到 `cordis.yml` 和一份依赖清单这两个事实源exe 与 `node` 双载体使用同一棵树和相同语义,开发验证无需等待打包;官方 Node 二进制消除了补丁版二进制的供应链顾虑。
**付出的**:产物约 174MB且源码原样进入 blob没有字节码混淆闭源分发诉求需要另行评估pkg 的 VFS/模块钩子层仍由社区维护(构建脚本钉死 `@yao-pkg/pkg@6.21.0`,升级需要显式改动);`--sea` 每个构建目标调用一次(与 CI 每个平台一个任务相匹配,本地多平台构建串行执行)。

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# RFC: Agent-scope runtime design and correctness
Status: implemented
## Problem
The [agent-scope contract](2026-07-08-agent-scope-contexts.md) is simple for contributors: register through `agent.ctx`, resolve one global-plus-agent view, publish only after setup, and retain the scope until work stops. The runtime must preserve that contract across a cooperative plugin framework, asynchronous creation, reentrant listeners, durable session commits, and worker or process failure.
The main design risk is adding a second mechanism for every race. Separate reservations, readiness sentinels, cancellation relays, snapshot layers, and protection registries can mirror the same fact until no reader can tell which one is authoritative. That machinery also encourages the runtime to treat trusted typed calls as hostile serialization boundaries.
The implementation needs enough state to preserve real ownership and settlement boundaries, but no more. A correctness reviewer must be able to follow one fact from acceptance through publication and teardown without reconciling parallel representations.
## Decision
The runtime uses one mechanism per independent fact. Scope routing has an opaque carrier; each live registry object has one entry record; each create or resume operation has one transaction; typed same-process calls borrow readonly values; real data boundaries materialize once; the cooperative prompt-assembly result is authoritative; and worker/process code retains separate terminal and quiescence state only where different owners can genuinely race.
The design can be skimmed as seven choices:
| Problem | Authoritative mechanism |
|---|---|
| Select global plus one agent's registrations | Opaque scope key and routing carrier |
| Own one live agent or session | One registry entry captured by its disposer |
| Coordinate create/resume | One `AgentCreationTransaction` |
| Protect durable, queued, model, or wire data | Materialize once at that boundary |
| Pass typed values inside one process | Readonly borrowed contract |
| Compose the model-visible prompt and tool surface | One shared tool view plus the authoritative assembly-waterfall result |
| Coordinate subagent, worker, and process shutdown | One cancellation signal plus the independent terminal/quiescence facts of that boundary |
The rest of this RFC expands those choices in dependency order: Cordis mechanics, scope routing, creation and session commit, tools and prompts, subagents and workflows, then executable checks.
The [July 8 RFC](2026-07-08-agent-scope-contexts.md) remains the contributor contract. The separate [subagent composition-controls RFC](../feature/2026-07-12-subagent-persona-tool-filter-and-depth.md) owns `persona`, `toolFilter`, and `maxDepth`; this document discusses only how their setup fits the lifecycle.
## Cordis model: context, fiber, effect, receiver, and waterfall
Five Cordis ideas are required to understand the implementation. A context selects services and registration ownership; a fiber is one live plugin or child lifecycle; an effect attaches cleanup to a fiber; an event receiver selects listeners; and a waterfall lets listeners transform or veto an operation in sequence.
### A context is an ownership path through one service graph
All agents share one Cordis service graph. A derived context does not clone `ToolRegistry`, `SystemPrompt`, persistence, or model adapters; it changes how registrations made through that context are tagged and which effects own their cleanup.
`agent.ctx` is such a derived context. Service calls still reach the shared instances, while a registration can inspect its calling context and store a contribution under the nearest scope key. Ordinary plugin contexts carry no scope key and therefore register globally.
### Fibers and effects make cleanup structural
A Cordis fiber is the live instance created when a plugin or child context is activated. Its state records whether that lifecycle is active, unloading, failed, or disposed. `ctx.effect()` and `ctx.on()` return disposers and also attach those disposers to the registering fiber, so unloading a plugin or agent scope removes everything registered through that context without a separate inventory.
The vendored Cordis fiber implementation establishes ownership before arbitrary setup or `internal/plugin` observers run. A reentrant unload can see the child fiber or effect that has started, reject effects added after unload begins, and join cleanup already started through a public single-shot disposer. Teardown observers are contained individually so one callback cannot prevent structural cleanup.
These are framework lifecycle guarantees rather than agent-specific policy. Agent creation depends on them because setup can activate arbitrary plugins and synchronously reenter owner disposal.
### Receivers route listeners; waterfalls compose decisions
Cordis filters listeners using the dispatch receiver (`this`), while harness listeners need an explicit agent, execution, request, or other subject. `Scoped<T>` marks the receiver expected by a scoped event declaration, but the runtime carrier deliberately exposes no subject API.
Product helpers therefore construct the carrier and pass the domain subject separately. This prevents listener routing from becoming an alternate object model and keeps event signatures understandable without knowledge of carrier internals.
A Cordis waterfall is middleware-style dispatch. Each listener receives `next()`: calling it delegates to the remaining listeners and base operation, while returning without it vetoes or replaces the downstream result. Waterfalls power prompt assembly and tool policy; ordinary emit events notify synchronously, and parallel events await all listeners without a veto result.
## Scope routing: one opaque key selects one layer
The scope package implements the smallest object needed for Cordis routing. Its carrier holds only a composed service filter and scope predicate, while the package records the opaque key privately and exposes the scope fiber's quiescent disposer separately.
### Scope identity uses object identity
A `ScopeKey` is an opaque object compared by identity. The harness uses the live `Agent` as its own key, but the primitive is domain-neutral and supports other scoped owners.
`createScope(parent, key)` returns a scope whose `ctx` shares the parent's services and whose effects are tagged with that key. `scopeOf(ctx)` reads the nearest registration key. `scopeTarget(base, key)` creates the event receiver whose filter preserves the base receiver's Cordis service filter, then admits unscoped listeners and listeners with that exact key.
The receiver is a small carrier rather than a transparent proxy for the domain object. Code that needs the agent receives the explicit event argument; code that needs registration ownership receives `agent.ctx`.
### Registry reads overlay one exact map
Scope-aware registries store global contributions separately from identity-keyed local contributions. A read resolves the global layer and at most one local layer; it never traverses parentage.
Each service retains its domain rule. Named prompt values and tools use local shadowing, tool restrictions filter globals before local tools are added, and events select listener audiences rather than registered data. Scope supplies identity and ownership, not a universal merge algorithm.
### Fused dispatch helpers prevent subject drift
`agentEvents(context, agent)` constructs the agent's carrier and injects the same agent as the event subject. Session, tool, approval, prompt, and subagent services likewise derive routing from the object they already own instead of accepting an unrelated key.
The type marker rejects ordinary bare-receiver mistakes, and development invariants cover direct JavaScript or casted dispatch. The subject remains explicit because routing correctness and useful event data are different concerns.
## Agent creation: one transaction owns the complete operation
Create and resume are one asynchronous lifecycle with several phases, not several lifecycles. `AgentCreationTransaction` owns caller and factory liveness, optional cancellation, private resources, publication, rollback, and the memoized teardown observed by every owner.
### Registry entries are the only live identity records
AgentRegistry and SessionStore each keep one entry per live object. The entry holds the stable ID, object, scoped carrier, and the small amount of publication or append state that belongs to that object.
A detach closure captures its exact entry. It deletes only when the map still points to that entry, so an old disposer cannot delete a later object that reuses the same ID. No registry rereads a mutable caller object to decide identity.
There is no reservation API. Caller-supplied IDs are admitted at final entry. Concurrent same-ID operations may both complete private setup; exactly one final `enter()` succeeds, and every loser rolls its private resources back. Sequential reuse is valid after the earlier disposer reaches quiescence.
### The transaction owns preparation before awaiting it
The transaction is installed under both the calling Cordis context and the concrete AgentLoop factory before persistence load or setup can suspend. It also observes an optional create/resume signal until the public operation settles.
Create prepares a new Session. Resume loads and validates the persisted Session before preparing the same live session identity. Both paths then build the scope, agent, and driver and invoke the same setup/publication algorithm.
The factory stores concrete trace targets but invokes them through a caller-bound Cordis trace. This preserves dependency origin and caller ownership without stacking trace proxies.
### Setup is trusted composition inside a private world
Setup receives the full child context and may await plugin activation. It can register tools, prompt sections, restrictions, listeners, and other effects, but the public contract does not support driving or publishing the in-flight agent through casts or internal registry calls.
The transaction races asynchronous load and setup against deactivation rather than waiting forever for a promise owned by external code. If cancellation or owner unload wins, public creation rejects after transaction-owned cleanup even when the external promise never settles.
### Publication has one ordered commit path
Publication admits and announces resources in the order required by observers:
1. Enter the session.
2. Enter the agent.
3. Announce `session/created`.
4. Announce `agent/created`.
5. Enable public driving.
6. Emit `agent/session-start`.
7. Start the driver.
The agent never drives before both registries and creation notifications agree. A synchronous listener may veto or dispose an owner; the transaction records publication in progress and waits for that callback stack to unwind before teardown continues. Every creation announcement that begins has a matching disposal announcement during rollback.
The sequence diagram isolates the non-obvious race: a synchronous creation listener can request disposal while the publication call stack still owns both registry entries. Teardown must deactivate immediately but wait for that stack to unwind before stopping and detaching anything.
```mermaid
sequenceDiagram
participant Tx as AgentCreationTransaction
participant Registries
participant Listener as Synchronous listener
participant Driver
Tx->>Tx: mark publication in progress
Tx->>Registries: announce agent/created
Registries->>Listener: invoke inside the same call stack
Listener->>Tx: dispose reentrantly
Tx->>Tx: deactivate, teardown waits for publication
Tx-->>Listener: disposal request accepted
Listener-->>Registries: return
Registries-->>Tx: announcement unwound
Tx->>Tx: resolve publication settlement
Tx->>Driver: stop and drain
Tx->>Registries: detach agent, then session
Tx->>Tx: dispose scope and resolve teardown
```
### Teardown preserves work before revoking registrations
Every teardown request joins one memoized path. The order is:
1. Deactivate creation or driving and let synchronous publication finish.
2. Stop and drain the driver, including idle injection flushes.
3. Detach the agent.
4. Detach the session.
5. Dispose the agent scope.
6. Retire transaction ownership tracking.
This order lets final agent and session events use the matching scoped listeners and keeps persistence observers attached through the final flush. Scope disposal comes last because registration revocation is the externally visible lifetime boundary.
## Session append: materialize, validate, commit, notify
Session events cross a durable boundary, so append owns their data. The rest of the algorithm uses one attached entry and one commit point.
### Durable data is materialized once
Session headers, seeds, and appended events are lossless JSON data. The Session constructor or append path materializes and validates them before storage and exposes frozen snapshots, so later caller mutation cannot change persistence, replay, or model reconstruction.
This is a real ownership boundary: the values leave the caller, may be persisted, and must reconstruct the same request later. It is intentionally stricter than a typed same-process callback or registry definition.
### Pre-commit listeners can veto; post-commit observers cannot
Append follows one sequence:
1. Materialize the durable event and surface intent.
2. Claim the SessionEntry and reject reentrant append on that entry.
3. Resolve scoped callbacks and run internal invariant validation.
4. Push exactly once; this is the commit point.
5. Notify each observer independently, containing synchronous and asynchronous failures.
6. Release append state and honor a detach requested during publication.
No observer error makes a committed event look uncommitted, and one bad listener cannot starve later listeners. Session invariants stage their transition before commit and apply it only when the same event reaches the contained post-commit observer.
`flush()` starts every persistence listener and awaits every result before reporting failure. This deliberate all-settled behavior prevents a synchronous failure from starving another backend or final flush.
## Trust boundaries: copy only when ownership actually changes
The runtime distinguishes typed in-process contracts from serialization and durability boundaries. This is the main simplification rule for values and callbacks.
| Boundary | Ownership rule |
|---|---|
| Typed service/plugin call in the same process | Borrow readonly values and callbacks |
| Parsed plugin configuration or external file | Validate semantic and structural input |
| Queued inbox message | Materialize before asynchronous consumption |
| Model/tool JSON input or output | Materialize at the model/tool boundary |
| Durable session or persistence data | Materialize and validate before commit |
| Worker, process, or wire message | Serialize, validate, and own the decoded value |
Tests that fabricate hostile getters, replace typed callbacks after handoff, or cast fake service objects do not define a production contract by themselves. The runtime keeps checks where data crosses a parser, queue, model, durable, file, worker, process, or wire boundary and relies on readonly types plus plugin discipline inside the trusted process.
Callback containment is separate from data ownership. Listeners are arbitrary extension code and can throw even when their arguments are trusted; publication and post-commit paths still contain failures according to their event contract.
## Tools and prompts: one view, authoritative assembly, committed outcomes
Tool presentation and execution share one private resolver. Prompt assembly remains trusted cooperative composition: registries supply the ordered input, and the assembly waterfall's returned value is exactly what the loop logs and sends. Execution uses separate one-way boundaries only where policy or outcome settlement must be monotonic.
### One resolver defines the tool view
The private resolver applies the current presentation mode, live global restrictions, exact local overlay, and local shadowing. Schemas, lookup, execution, Code Mode SDK generation, and restriction validation all use that resolver or its pre-restriction global-name view.
The [subagent composition-controls RFC](../feature/2026-07-12-subagent-persona-tool-filter-and-depth.md#tool-filtering-is-one-live-global-view-rule) owns the user-visible allow/deny semantics. The implementation requirement is agreement: a filtered-away global cannot remain executable through a different lookup path, and a locally shadowed definition is the same definition presented and executed.
`ToolRestriction` accepts readonly allow/deny names and compiles them into internal sets. Multiple restrictions intersect. Public `visible()` and `knownNames()` methods are unnecessary because only the registry needs the intermediate views.
### Tool execution owns identity and boundary materialization
The registry assigns every execution a fresh branded `Symbol` token. Nested Code Mode calls carry the outer token as `parent`, so structured output can correlate an inner capture with its enclosing `run_code` result by identity.
A fresh registry-assigned Symbol provides collision-free execution identity without a WeakSet membership registry. Callers cannot supply the execution's own token through `ToolExecutionInput`; they only receive the pipeline-owned `ToolExecution` after the registry creates it. This is a trusted typed contract, not a runtime defense against arbitrary casts or JavaScript callers.
Arguments are materialized once where model/tool JSON enters the pipeline. Pre-, around-, and post-execute listeners operate on the typed execution and decisions. Call ID correlation, approval, monotonic guards, and Code Mode nesting remain explicit relational checks.
After the last post-execute listener, the registry materializes and freezes the accepted final result once. Every synchronous `tools/result` observer receives that exact committed object, and observer failures are contained individually. An outer pipeline failure is normalized into a committed error result, so observers can discard staged work against the same authoritative boundary.
### The assembly waterfall owns the final model-visible composition
SystemPrompt first resolves the global-plus-agent sections, variables, and tool providers into a deterministic registry contribution. The scope-filtered `system-prompt/assemble` waterfall may then reorder, replace, add, or remove any section, variable, or schema. Its returned assembly is authoritative; there is no later restoration pass and no finality metadata on ordinary prompt sections, tool definitions, or provider results.
This is a trusted same-process extension seam, not an authority boundary. A listener that changes Code Mode's `run_code` schema or `tools:sdk` instructions, or a structured child's capture schema or instruction, owns preserving a coherent protocol in the assembly it returns. ToolRegistry still reserves `run_code` against ordinary tool registration and restriction because those are registry invariants, but assembly middleware remains free to transform the final model-visible surface.
Scope solves the real isolation problem directly. Structured-output contributions register in the child's exact scope, while Code Mode derives its transport and SDK from the same resolved tool view. A second named-protection system would need another ownership and collision rule across arbitrary schema providers—including providers that intentionally contribute duplicate names—without creating a new trust boundary.
### Structured output commits only authoritative outcomes
Structured output combines child-scoped composition with a two-phase execution commit. The child registers its `structured_output` tool and instruction before publication; a trusted assembly listener may transform those ordinary contributions and is responsible for preserving the protocol if the child is expected to complete. The tool body validates a candidate and stages it by the current `ToolExecution`, but successful capture is decided only by immutable `tools/result` observations.
For a native call, the observer deletes the stage and commits its value only when that exact execution's final result succeeds. A post-execute block or outer pipeline failure therefore cannot leave a captured value behind.
For a Code Mode SDK call, the inner successful result records `{ parentToken, value }` rather than committing. The observer waits for the `run_code` execution whose token matches `parentToken` and commits only if that outer final result also succeeds. Program failure, runtime abort, or outer post-policy denial discards the pending value.
Once a value is pending or committed, a scoped monotonic guard denies later tool calls. After commit, the ordinary serial `agent/turn-stop` listener returns a stop decision after continuation and steering have already folded. A schema-validation failure remains an ordinary `INVALID_ARGS` tool error and leaves the child able to retry within the same turn.
Pure Code Mode's registry contribution omits `structured_output` from native wire schemas and exposes it through the generated SDK. The assembly waterfall may deliberately change that presentation; execution still validates against the child-scoped definition, and the listener owns the consistency of any alternate model-visible route it creates.
### Three execution boundaries are deliberately one-way
Prompt assembly is intentionally cooperative, but three execution facts need one-way settlement after their extensible stages:
| Boundary | Final power | Why ordinary listener order is insufficient |
|---|---|---|
| Tool pre-policy | Deny monotonically | A later listener must not re-allow an already denied call |
| Tool result | Observe the immutable committed outcome | Structured output must commit only the result that actually escaped the pipeline |
| Turn continuation | Stop after ordinary continuation folding | A committed terminal output must end the turn |
`ToolGuard` is the monotonic policy registry. Committed tool observation is the contained `tools/result` point described above. Terminal structured output listens on the ordinary serial `agent/turn-stop` fold after normal continuation and steering decisions; no public `strictSerial()` dispatcher is needed for the typed listener contract.
### Skill and approval services trust typed callers
Skill registry definitions and approval policies are readonly same-process contracts. Their services do not clone callback objects or defend against post-handoff callback replacement.
Skill still validates external skill files and parsed provider output, routes catalogs through the calling agent's tool view, and disposes registrations exactly. Approval still resolves policy, observes cancellation, routes `approval/request` by `request.agent`, records the durable audit pair, and contains answerer and post-commit observer failures.
## Subagents: readiness is the start promise
Subagent startup has one ownership transfer. The provider owns partial resources until its start promise fulfills with a ready published run; the caller owns the returned run and must dispose it.
### The service contract has one cancellation channel
`SubagentProvider.start()` and `SubagentService.start()` return `Promise<SubagentRun>`. The promise fulfills only after the backend has established the child it promises, so callers and `subagent/start` observers never need a second `run.started` readiness promise.
`SubagentStartRequest.signal` is required. Aborting it requests cancellation during startup and after readiness. `SubagentRun.dispose()` also requests cancellation and awaits quiescence. There is no separate public `run.cancel()` channel.
Optional `sendMessage()` supports a live backend that can accept steering. Optional `resume()` returns `Promise<SubagentRun>` because the resumed child has the same asynchronous readiness boundary.
The service validates provider capabilities and request semantics before calling the provider. A provider rejection cleans any partial resources before the rejection escapes and emits no `subagent/start`/`subagent/end` pair. After fulfillment, the service attaches result observation, emits scoped start, and returns the run. Provider removal prevents later starts but does not revoke a run already accepted by the provider.
### In-process providers reuse the core transaction
Spawn and fork share one in-process driver. It creates the child through `parent.ctx`, passes the required signal into the core creation transaction, and installs persona, tool restriction, and structured-output contributions during unpublished setup.
The provider awaits creation and returns only the published run. At the handoff, core creation detaches its creation-only abort listener; the provider immediately rechecks the signal before installing the live-run listener, so an abort in that narrow interval disposes the new handle instead of escaping cancellation. Parent teardown follows the child because the operation belongs to `parent.ctx`; provider unload blocks new starts but does not become a second revocation owner for accepted runs. The run disposer cancels the child and awaits the AgentHandle's ordered teardown.
Spawn uses an empty session seed. Fork uses a validated completed-turn prefix. Conversation seeding changes history only and does not import scope, tools, services, or authority.
### ACP providers own the process until readiness or cleanup
An ACP provider crosses a real process and wire boundary, so it retains validation, environment scrubbing, message serialization, abort/process races, and kill-to-exit quiescence.
Start resolves only after `initialize` and `newSession` succeed. Abort, spawn failure, RPC failure, or invalid startup response reaps the process before rejection. After readiness, result maps the ACP prompt outcome and streamed output; dispose requests cancellation, closes the connection, and awaits process exit through one memoized path.
## Workflows and ACP UI: retain only independent async facts
Worker and editor bridges need more state than same-process registries because messages, process death, and rendering can settle independently. Their state is organized around those real facts rather than duplicate cancellation protocols.
### Workflow children are pending starts or published records
The workflow host keeps pending provider-start promises and published child records. A child moves from pending to published only when async `SubagentService.start()` fulfills; rejected starts clean their partial provider work and produce no child lifecycle pair.
One host-owned AbortController supplies the required signal to pending and live children. Closing workflow admission aborts that signal, so there is no duplicate `ChildCancel` worker RPC or explicit host-side `run.cancel()` fanout. Quiescence waits for both pending starts and published child disposal.
The worker boundary still serializes requests and outcomes. The host retains first-terminal-outcome arbitration, exact child accounting, worker-death handling, grace termination, late/duplicate message rejection, and bounded cleanup because result receipt, worker exit, and child quiescence are genuinely independent facts.
### Terminal result and physical cleanup remain separate
The workflow result records the first accepted terminal outcome according to the public precedence rules. Cleanup can continue after that result is chosen: live children still need disposal, a worker still needs termination, and a slow external backend may outlive the configured grace bound.
Public disposal claims its memoized promise before invoking callbacks. Worker death closes admission before processing any queued late child request, synthesizes missing lifecycle ends, and starts child/process cleanup without rewriting an outcome already claimed.
### ACP prompt settlement does not depend on rendering success
The ACP UI correlates a prompt with its observed turn directly. It does not scan from a `logWatermark` or use session status as a second reconciliation oracle.
Prompt handling settles correlation in a `finally` around transcript rendering. A rendering failure can fail presentation, but it cannot skip prompt settlement or leave the session permanently in flight. Concurrent loads of the same persisted caller-supplied session ID remain excluded because that is a real persistence identity race, not a UUID collision concern.
## Correctness enforcement
The design is enforced at types, runtime escape points, generated contracts, and behavioral tests. No one layer is asked to prove what it cannot observe.
### Types make the ordinary path hard to misuse
Readonly contracts describe borrowed same-process values. `Scoped<T>` marks event receivers, `agentEvents()` fuses carrier and subject, tool inputs omit registry-owned tokens, and subagent async return types expose readiness directly.
TypeScript cannot govern JavaScript casts, direct Cordis dispatch, process messages, or durable files, so runtime enforcement remains at those escape points.
### Runtime invariants cover cross-service facts
The invariants plugin verifies that every declared scoped event uses a marked carrier and that event families exposing a subject use the matching key. Session trace validation stages before append commit and advances after the same event commits.
The plugin does not police trusted setup by scanning registries or reject prompt assembly objects fabricated through casts. Those checks would turn composition contracts into speculative runtime machinery without protecting a real external boundary.
### Generated artifacts keep public contracts aligned
The event catalog, service catalog, producer/consumer matrix, configuration catalog, module graph, tool catalog, type-equivalence blocks, and scoped-event resolver map are generated or freshness-gated from source. The [TypeScript semantic-gates RFC](../process/2026-07-14-typescript-program-backed-semantic-gates.md) owns Program construction, semantic event discovery, and resolver-generation rules.
Behavioral tests pin scoped routing and disposal, final-entry collision cleanup, publication rollback, ordered quiescence, durable pre/post-commit behavior, live tool filtering across presentation and execution, cooperative prompt assembly, structured-output commit in native and Code Mode, async subagent startup and signal cancellation, worker terminal arbitration, ACP settlement, and process teardown.
## Alternatives considered
The [July 8 RFC](2026-07-08-agent-scope-contexts.md#alternatives-considered) owns alternatives to the public flat-scope contract. The alternatives here concern implementation shape.
### Use a transparent proxy as the scope carrier
A proxy that impersonates the subject must preserve property, callable, constructable, private-field, descriptor, and proxy-invariant behavior that listener routing never needs. A small opaque carrier keeps the filter and key while the explicit event argument carries the subject.
### Reserve agent and session IDs before setup
Reservations prevent duplicate private setup work but require cross-service capabilities, release ordering, abandoned-reservation cleanup, and prepared-object binding. IDs are caller-supplied and concurrent reuse is caller error; final entry can choose the winner while the losing transaction rolls back cleanly.
### Snapshot every typed same-process argument
Universal copying defends against stateful getters and callers that violate readonly contracts, but it adds allocation, duplicated validators, and paths that can forget to copy. Materialization belongs at parser, queue, model, durable, worker, process, and wire boundaries where ownership actually changes.
### Give readiness, cancellation, and disposal separate controllers
Parallel sentinels can all mirror whether one operation is live. One transaction or start promise owns the operation; separate promises remain only where publication unwind, external work, terminal result, and physical quiescence can settle independently.
### Keep synchronous subagent start plus `run.started`
This splits provider acceptance from readiness and forces every consumer to register a partial run, attach result observation, await readiness, and clean up readiness failure. An async start promise makes provider-to-caller ownership transfer the readiness boundary itself.
### Restore selected prompt or tool contributions after assembly
A post-waterfall restoration pass would create a second composition rule after the documented cooperative seam. Correctly assigning canonical presence or absence would also require provider ownership and collision rules for arbitrary tool-schema providers, whose ordinary output may contain duplicate names. Scoped registration already supplies the required per-agent isolation, and trusted assembly listeners own the protocol consistency of what they return, so named restoration adds machinery without establishing an independent boundary.
### Remove worker/process lifecycle guards with same-process hardening
Worker messages, process death, and durable input do cross ownership and serialization boundaries. First-outcome arbitration, validation, environment scrubbing, and quiescent process cleanup remain necessary even though hostile same-process callback machinery does not.
## Consequences
The implementation is smaller and its proof follows the same shape as its ownership graph. One key selects a layer, one entry owns a live registry object, one transaction owns creation, one resolver owns a tool view, and one async promise transfers subagent ownership.
### What the design guarantees
- A scoped contribution is visible only in its exact agent view and is disposed with that scope.
- Create and resume expose no partially configured handle; final-entry losers and publication failures clean every prepared resource.
- Disposal retains scoped listeners and persistence through driver drain and final session work, then revokes the scope.
- Durable, queued, model, worker, process, and wire values are owned at their real boundary; typed same-process values follow readonly contracts.
- ToolRegistry's presentation, lookup, and execution resolve the same live view before expert assembly transforms, and committed results have one immutable observation point.
- Registry contributions are deterministic inputs, while the trusted assembly waterfall owns the final model-visible composition.
- Subagent start returns only a ready run, required signals cancel pending or live work, and disposal reaches the backend's quiescence contract.
- Worker/process result precedence and cleanup remain correct under death, late messages, and bounded teardown.
### Costs and limits
Scope-aware services still maintain global and identity-keyed maps, and operations must carry their real agent explicitly. Async create/resume and subagent start require callers to await ownership transfer and dispose returned handles.
A trusted `system-prompt/assemble` listener can remove or replace Code Mode and structured-output protocol pieces. This is deliberate: the listener owns final composition and must preserve any protocol the deployment expects to remain usable.
The design trusts typed plugins in the same process. It does not defend against arbitrary casts, stateful getters, mutation that violates readonly contracts, or a plugin deliberately using ambient service access outside the supported composition API.
The [security and authority non-goal](2026-07-08-agent-scope-contexts.md#security-and-authority-are-non-goals) remains fundamental. These mechanisms prove registration composition, publication, and lifetime ownership; they do not prove confinement or parent-to-child non-escalation.

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# RFC: Agent Client Protocol (ACP) support — drive the coding agent from external editors
Status: implemented
## Problem
The harness originally exposed agents only through a readline loop. That surface could carry text, but it gave an editor no structured way to create or resume sessions, correlate prompt completion, stream reasoning and tool activity, render tool-specific UI, ask for permission, or cancel one conversation without disturbing another. ACP defines those interactions as JSON-RPC over stdio, and Zed is the target client used to make concrete compatibility decisions.
The bridge must preserve the harness's existing ownership boundaries. It cannot depend on the concrete agent loop, bypass the tool registry, execute shell commands in the editor, or invent a second source of session truth. stdout is also the protocol transport, so any accidental log output corrupts the connection.
## Decision
`@deepseek-ai/dsh-acp` is a UI/client-driver plugin under `packages/ui/acp`. It uses `@agentclientprotocol/sdk`'s `AgentSideConnection` over stdin/stdout and programs only interface services: the agent create/resume factory, session persistence, tool registry, user interaction, and optional approval/bash capabilities. It does not change the agent loop and is not a capability-seam implementation.
The bridge implements the following stable session path:
- `initialize` negotiates the protocol version, advertises text plus `resource_link` prompts, and advertises `loadSession`.
- `session/new` validates an absolute `cwd`, stores it in `SessionHeader`, creates an agent through `ctx.agents`, and returns any composition-backed config options.
- `session/load` validates the requested cwd against persisted metadata before constructing an agent, reserves the id across the asynchronous resume, replays user/assistant/tool events as ACP updates, and reports the resumed config-option fold.
- `session/prompt` accepts text and resource links, rejects unsupported or empty content, allows one in-flight prompt per session, and settles against that prompt's owning `turn/end`. An error turn rejects the RPC; other closed turn reasons map through a total ACP stop-reason codec.
- `session/cancel` calls the queue-aware agent cancel path and settles only the addressed session's prompt.
Tool-call presentation remains tool-owned. A tool's `presentCall` and `presentResult` return the `generic`, `terminal`, or `diff` render-intent variants; the bridge switches on that union and maps it to ACP. Presenter-less tools receive a generic fallback. Bash terminal cards use Zed's capability-gated `_meta.terminal_info`, `_meta.terminal_output`, and `_meta.terminal_exit` convention; the harness still executes the command through `ctx.bash`, preserving sandbox, environment scrub, ownership, and cwd. Clients without that extension receive ordinary text content. Filesystem tools provide diff cards and file locations without hard-coded tool-name branches in the bridge.
Permission handling is an answerer on the [user-approval seam](2026-07-06-approval-seam.md), not an ask-every-tool policy in ACP. An `approval/request` for a bridge-owned agent with a call id becomes `session/request_permission` on that agent's editor session, with one-shot allow/reject choices. Foreign or call-less requests delegate; a missing or failed answerer remains fail-closed. The plugin that asks—such as a pre-execute policy or bash escalation—owns the decision to ask.
When `ctx.permission` is composed, the bridge exposes one `permission` select from the deployment's preset table. The shipped `workspace-write` and `danger-full-access` presets each bundle a sandbox mode with an approval policy; unmatched effective knobs produce the switch-away-only `custom` state. `session/set_config_option` validates through `PermissionService.set()` and writes both owning knob events. A switch during an open turn appends immediately; an idle switch is overlaid in responses and anchored at the next `agent/prompt-submit`, before request assembly. Until then it is memory-only, so a crash restores the durable fold. ACP session modes are not modeled because config options are the forward protocol surface; `AcpConfig.model` remains connection-wide.
The bridge also provides the ACP-backed `UserInteractionProvider`: `ask_user_question` requests become form elicitations on the owning session. Select, multi-select, option descriptions, and custom-answer override semantics are preserved.
Lifecycle ownership is explicit. The bridge holds an `AgentHandle` per live session. Disconnect and Cordis disposal cancel pending prompts, dispose every handle in parallel, await loop quiescence and persistence flush, and then remove the records. Stream notification failures are contained so a vanished client cannot corrupt an agent turn. The ACP app composition loads no stdout logger; a test guards stdout as framed JSON-RPC only.
The precise supported and deferred protocol rows live in [`packages/ui/acp/acp-feature-support.md`](../../../../packages/ui/acp/acp-feature-support.md); the package README is the operational contract.
## Alternatives considered
**A prepended `tools/execute` listener that asks on every ACP-owned call** — rejected. It would hard-code permission policy into the UI bridge, ask even when no policy requires it, and could not serve approval requests that arise after execution begins. The shared user-approval seam keeps mechanism, asking policy, and UI answerer separate.
**Inject the concrete `agentLoop`** — rejected. Agent creation, resume, idle observation, and disposal are interface-level ownership operations on `dsh-agent`; a UI plugin does not need a dependency-rule exception.
**Execute bash through ACP `terminal/*`** — rejected. That would move execution outside the harness and bypass its sandbox, credential scrub, task ownership, cwd resolution, and session log. Terminal metadata is presentation only.
**Represent permission presets as ACP session modes** — rejected. The deployment-defined preset is already one config-option select, while session modes are the legacy surface slated for removal in ACP v2.
**Hijack stdout defensively** — rejected. Process-wide monkey-patching is outside Cordis effect ownership and races the protocol transport. The app composition owns stdout purity.
## Consequences
Editors can create, load, prompt, cancel, render, ask, and reconfigure multiple harness sessions over one ACP connection without a loop-specific dependency. The session event log remains the durable source for replay, prompt settlement, cwd, and per-session configuration. Tool presentation and human-answer channels remain extensible plugin contracts instead of ACP-specific behavior.
The bridge deliberately does not implement session list/delete/resume/close capabilities, MCP passthrough, additional directories, image/audio/embedded-resource prompts, runtime model selection, plans, slash commands, usage updates, editor filesystem delegation, or the ACP terminal execution sub-protocol. The feature checklist records these as unsupported rather than silently accepting them.
An idle config selection is truthful in the live response but not durable until the next `agent/prompt-submit` anchors it inside the open turn. Crashing before that boundary loses the pending selection; this is the cost of keeping session events turn-enclosed and replay-safe.
## Verification
The ACP suites cover the in-memory protocol codec, create/load replay, exact prompt settlement, cancellation races, unsupported content, tool presentation, terminal capability fallback, permission outcome mapping, config-option validation and persistence, multi-session isolation, disconnect/disposal quiescence, and HMR cleanup. Snapshot and built-bin tests exercise the app composition, while the real-API e2e self-skips without a key.

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# RFC: Multiplex concurrent ACP sessions over one connection
Status: implemented
## Problem
An ACP editor can keep several conversations alive over one agent subprocess. A single-active-session bridge would force extra processes and would not match Zed's client model, which tracks multiple session ids and concurrent loads. Multiplexing introduces isolation risks: events, prompt completion, cancellation, permission prompts, config selections, and predictable background-task ids must never cross session boundaries.
## Decision
The ACP bridge stores live sessions in `Map<SessionId, SessionRecord>` and keeps a `WeakMap<Agent, SessionId>` reverse index for agent-scoped callbacks. A record owns its agent handle, in-flight prompt, live tool-call presentation state, pending idle config switches, session cwd, and client capability snapshot. A separate loading-id set reserves each id before asynchronous resume so two pipelined loads cannot construct duplicate agents; distinct ids may load concurrently.
Every `session/event` and `agent/status` callback resolves the owning record before sending or settling anything. Each session permits one in-flight prompt independently. The prompt records a log watermark, captures its own `turn/start`, and settles only on the matching `turn/end`; a late end from a cancelled prior turn cannot resolve a newer prompt. `session/cancel` addresses one record and calls only that agent's queue-aware cancel path.
Permission ownership uses the same reverse index. The ACP `approval/request` answerer prompts only the editor session that owns the requesting agent and delegates foreign requests. User-interaction elicitations likewise route by agent ownership. Per-session sandbox and approval config values fold only that session's events, with pending idle switches stored on that record until the next turn anchors them.
Background bash tasks carry an opaque owner token equal to the owning session id. `bash_output` and `bash_kill` compare the caller's token with the executor's task ownership before reading or killing; a predictable task id alone grants no access. Ownership is stored with the executor task, so a tool plugin reload does not erase it.
Connection teardown clears the live map, settles each pending prompt as cancelled, and disposes all `AgentHandle`s in parallel. Each handle stops and awaits its loop, flushes the session while attached, unregisters the agent, and removes the session. Teardown is memoized and shared by client disconnect and plugin disposal.
## Alternatives considered
**One live session per connection** — rejected. It adds process overhead and contradicts the target client's multi-session shape without removing multiplexing needs from the editor.
**A per-session `ctx.extend()`** — rejected. A child context does not by itself create a child plugin fiber, so listeners would still belong to the bridge fiber. The implemented bridge instead uses global listeners with explicit O(1) demultiplexing and per-session owned records; agent lifecycle is owned by `AgentHandle`.
**Agent object identity as bash-task ownership** — rejected. A resumed or replaced agent object may legitimately represent the same durable session. The opaque session token is the cross-boundary identity that should survive plugin reloads.
## Consequences
N sessions can stream, prompt, request permission, switch config, and run background tasks concurrently without interleaving or cross-settling. A cancel or dispose in one session does not affect its neighbors. The bridge pays for explicit maps and isolation tests, but it does not add one listener set per session and therefore avoids listener fan-out during long-lived connections.
The bridge still exposes no protocol method to close one live session independently. Today records leave together on connection teardown; session close/resume lifecycle capabilities remain deferred in the ACP feature checklist.
## Verification
The multi-session suite drives concurrent sessions through interleaved updates, independent in-flight prompts, targeted cancellation, same-id and distinct-id load races, permission routing, config isolation, and teardown. Tool-bash tests prove one session cannot read or kill another session's background task.

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# RFC: Code Mode — the model writes TypeScript against the tool registry
Status: implemented
## Problem
In the registry's native presentation, the agent loop advertises every visible capability as a JSON-schema function definition. `ToolRegistry` contributes its schemas to the system-prompt assembly, the assembly's `tools` land on the wire (and in the logged request header), the model invokes one `tool-call` block per step, and the loop dispatches each call through `ctx.tools.execute()` **sequentially** (parallel tool execution is an explicit open TODO in `dsh-tools` and [docs/architecture.md](../../../architecture.md)), with **every** intermediate `tool-result` re-entering the model's context on the next request.
For multi-step tool work this is token-heavy and serial. The model cannot compose tools — loop over a result set, branch on an intermediate value, fan out, post-process — without a full model round-trip per call, and each round-trip drags the entire intermediate result back into context whether the model needs it or not.
Cloudflare's [Code Mode](https://blog.cloudflare.com/code-mode/) proposes an alternative grounded in a simple observation: LLMs are better at writing code than at emitting tool calls, because they have seen millions of lines of real code and comparatively few contrived tool-calling traces. Instead of one tool call per step, the model writes a TypeScript program against a generated API over the tools, the program executes in a sandboxed runtime, and the model curates what comes back — only what it prints or returns — instead of every intermediate result.
Tool presentation belongs to the registry that owns tool visibility: implementing a second presentation as an after-the-fact waterfall transform would make correctness depend on listener order and fight [reconstructable requests](../../implemented/architecture/2026-07-05-reconstructable-requests.md). The execution substrate is also part of the foundation rather than a placeholder: Node `worker_threads` provides a separate isolate, an empty environment, heap caps, and termination of a hot synchronous loop, while fitting the harness's existing trust model (§Trust posture).
## Decision
Three decisions, each elaborated in its own section below:
1. **Code Mode is a first-class presentation mode of `ToolRegistry`** (`dsh-tools`), selected by a validated `mode` config: `'native'` (the default, contributing the visible capability schemas), `'code'` (the registry contributes only its reserved `run_code` transport plus a generated SDK `.d.ts` in the system prompt), or `'both'` (native schemas and the transport + SDK). The registry shapes its canonical contribution at the source; the cooperative prompt-assembly result remains authoritative, and the logged request header records exactly that returned presentation.
2. **Code execution is a capability seam**`packages/code-runtime/` contains the interface package `@deepseek-ai/dsh-code-runtime`, which owns `ctx.codeRuntime` ([capability seams](../../implemented/architecture/2026-06-13-capability-seams.md); consumer = `dsh-tools`, with core-consumes-a-seam precedent in `agent-loop``dsh-llm`). The runtime knows nothing about tools: it is handed a program and named async bindings, runs the program, and reports `{ value, logs, error? }`. Language and substrate are backend properties, so a future Python or container backend is another implementation package, not a redesign.
3. **The shipped implementation is `@deepseek-ai/dsh-code-runtime-worker`**: one fresh Node worker thread per run, executing the model's TypeScript after type-strip, with bindings bridged over the message port, an empty environment, configurable heap/output/time caps, and hard termination. Its trust posture is bash-equivalent by design — no unsafe-acknowledgement flags — because the harness already ships `dsh-bash-local`, which executes arbitrary model-written shell commands with strictly *more* ambient authority.
### The registry owns the mode
`ToolRegistry` gains a schemastery-validated config (`static Config`), its first: `mode: 'native' | 'code' | 'both'`, default `'native'`. A deployment flips it from `cordis.yml` (`tools: { mode: code }`) — no code edit, per the no-hardcoded-tunables convention.
**Wire tool list.** The registry contributes visible capabilities in `'native'`, only `run_code` in `'code'`, and both in `'both'`. The final `PromptAssembly.tools` list is logged in the request header. `run_code` is a reserved presentation transport outside registration and restriction layers; direct prompt providers and the assembly waterfall remain responsible for their own contributions.
**Interaction with `toolOrder`, stated up front:** a configured `systemPrompt.toolOrder` naming native capabilities rejects every assembly under `mode: 'code'`, because those names are outside that mode's wire-validation universe. This is correct behavior, not a bug: a deployment using Code Mode updates its order config or drops it.
**SDK prompt section.** In `'code'` and `'both'`, the lazy `tools:sdk` section in the tool-guidance order band renders TypeScript declarations plus fixed usage instructions for the scope's visible capabilities. It shares lookup and execution visibility, excludes `run_code`, and sorts tools lexicographically for byte-stable output.
**Assembly ownership.** `run_code` and `tools:sdk` enter the trusted `system-prompt/assemble` waterfall as normal assembly inputs. A scoped `tools:sdk` section may shadow the global default before dispatch, and a listener may remove or replace either contribution. The waterfall's returned assembly is final, so whoever changes these inputs owns preserving a viable Code Mode protocol when the deployment expects Code Mode to remain usable; no restoration pass overrides deliberate composition.
**Codegen.** `jsonSchemaToTs()` maps the `defineTool` JSON-Schema subset to TypeScript, carries schema descriptions into JSDoc, and degrades unsupported constructs to `unknown`. The SDK exposes tools as quoted object keys, supporting arbitrary names without aliases or collisions. Typing is advisory because the runtime strips types before execution.
### The run_code tool and the dispatch bridge
Under `'code'` and `'both'` the registry owns `run_code` as a reserved presentation transport with one required parameter, `{ code: string }`. It is represented by a normal `ToolDefinition` for dispatch but stays outside the filterable capability layers, so restrictions cannot accidentally remove Code Mode's only entry point. Calls traverse the complete tool pipeline — `tools/pre-execute` → monotonic guards → `tools/execute` around dispatch → `tools/post-execute` → immutable `tools/result` notification — exactly like native calls; a permission plugin can inspect the program text before it runs, and final-result observers see the normalized outer outcome. Its `execute(args, exec)`:
1. **Build bindings.** One run-scoped signal follows outer cancellation and is aborted whenever the run settles. Each visible tool binding JSON-normalizes its arguments—rejecting lossy values before dispatch—waits on the serialization queue, executes with a deterministic call id and the outer token as `parent`, defers returned contexts through the outer execution, and logs `tool/code-dispatch`. Successful text becomes a string and non-text blocks become placeholders; tool errors reject the binding promise. Every sub-call retains its own immutable execution identity and traverses the full tool pipeline.
2. **Runs the program**: `ctx.codeRuntime.run({ program: args.code, bindings: [{ global: 'tools', functions }], signal: runController.signal })`. The runtime receives the run-scoped signal, not only the caller's outer signal, so any way the outer run settles also aborts work inside the runtime.
3. **Settle after quiescence.** When the runtime settles, the bridge aborts outstanding work and drains the dispatch queue before returning. Success returns captured output and presentation metadata. A runtime failure becomes `CodeRunFailedError`; backend rejection uses the registry's normal error boundary. Both produce structured error results, and no sub-call can append after `run_code` settles.
**Sub-call contexts are deferred through the parent.** Injecting inside `run_code` would break parent call/result adjacency, so `ToolRunContext.deferContext()` collects every sub-result `additionalContexts` entry in dispatch order. The registry carries that array even when the program later throws, and the loop appends each entry only after the outer result and every sibling result in the step. An outer post-execute block discards tool-deferred entries and exposes only contexts explicitly attached by the blocking decision.
**Concurrency is serialized.** Each run owns a dispatch queue, so even `Promise.all` executes tool calls in submission order. Settlement abandons queued calls that have not started. Parallelism requires per-tool concurrency-safety metadata.
**Presentation.** `run_code`'s render intent is decided here per the [render-intent RFC](../../implemented/architecture/2026-07-02-tool-render-intent-union.md): `presentCall` → a `generic` card, `kind: 'execute'`, title = the program text, `rawInput` = the same program text; `presentResult` → a `generic` card whose content is the captured output (from `meta`). The program is the title because ACP execute cards reliably render that field while some clients omit body and raw-input content. This is not a `terminal` card: that card's semantics are "a shell command in a working directory", which a program is not.
### Observability: `tool/code-dispatch`
Each sub-dispatch appends a log-only `tool/code-dispatch` event containing parent and child call ids, tool identity, normalized arguments, and result summary. It remains outside model history but available to persistence and UIs. Appends occur inside the open `run_code` turn. Direct executions without an agent still run but cannot log the event.
### The code-runtime seam
`packages/code-runtime/code-runtime/``@deepseek-ai/dsh-code-runtime`, depending only on `cordis`. An abstract `CodeRuntime extends Service` (`super(ctx, 'codeRuntime')`) plus the vocabulary:
- `CodeRunRequest = { program: string; bindings: CodeBindingNamespace[]; signal?: AbortSignal }`
- `CodeBindingNamespace = { global: string; functions: Record<string, (args: unknown) => Promise<unknown>> }` — the runtime exposes each namespace as a global object of async functions inside the program; binding arguments and resolutions must be structured-cloneable (a runtime may cross a serialization boundary; ours does).
- `CodeRunResult = { value?: unknown; logs: CodeLogEntry[]; error?: CodeRunFailure }` — program execution outcomes, including exception, timeout, abort, and worker exit, resolve as the `error` field. `run()` may reject only for caller/seam misuse (for example a duplicate binding namespace); consumers still contain a non-conforming backend rejection at their own error boundary.
- `CodeLogEntry = { source: 'console' | 'stdout' | 'stderr'; level?: 'log' | 'info' | 'warn' | 'error' | 'debug'; text: string }`
- `CodeRunFailure = { kind: 'exception' | 'timeout' | 'abort' | 'worker-exit'; message: string }` — orthogonal outcomes reported independently per [defensive patterns](../../../defensive-patterns.md); a timed-out run is not an exception, an abort is not a timeout.
- Two readonly backend descriptors, informational not gating: `language` (what the program must be written in — `'typescript'` for the shipped backend; a Python backend would say so, and pair with its own SDK generator on the presentation side) and `isolation` (`'worker-thread'` for the shipped backend; `'process'`, `'container'`, … for future ones). `dsh-tools` requires `language === 'typescript'` in the MVP — its codegen emits TS — and fails the assembly loudly otherwise, the same misconfiguration idiom as `toolOrder` violations (as when `mode` is non-native with no `ctx.codeRuntime` loaded at all).
Requests contain every runtime input; implementations own validated timeout and cap defaults. The registry looks up the optional runtime only when Code Mode is assembled, so native mode does not depend on one. Missing or language-incompatible runtimes fail loudly. Alternate substrates or languages can replace the implementation behind the same seam, paired with the appropriate SDK generator.
### The worker-thread runtime
`@deepseek-ai/dsh-code-runtime-worker`, the second package of the `packages/code-runtime/` group. Per `run()`:
1. **Type-strip host-side** with Node's built-in `stripTypeScriptTypes` (`node:module`; present across the repo's whole engines range, `^22.19.0 || >=24.0.0`, and position-preserving, so runtime error line numbers match the model's source). Strip-only mode rejects non-erasable syntax (`enum`, namespaces) — that rejection returns as `error.kind: 'exception'` with Node's message, the SDK instructions say "erasable TypeScript only", and the model self-corrects like any other program error. A syntax-level failure never spawns a worker.
2. **Spawn one fresh `Worker` per run** from the package's own bootstrap module: `env: {}` (truly empty — stronger than the scrubbed-env rule for spawned commands), `resourceLimits` from config, `stdout`/`stderr` captured into `logs` rather than inherited. No pooling and no cross-run state: a program's world dies with its worker, which keeps runs reconstructable from the log alone and makes state bleed unrepresentable.
3. **Execute** in the bootstrap: the stripped program becomes the body of an `AsyncFunction` whose parameters are the binding globals and a capturing `console` shim, so top-level `await` and `return` work and the program's completion value is the run's `value` (structured-cloneable values cross as-is; anything else is replaced by its `util.inspect` rendering, documented).
4. **Bridge bindings over the message port**: each binding function in the worker posts `{ id, global, name, args }` and awaits the reply; the host validates the name against the request's bindings, invokes, and replies `{ id, ok, value }` or `{ id, ok: false, message }` (a host-side binding rejection becomes a program-side rejection). The worker-side namespace objects are built null-prototype via `defineProperty`, so a binding named `__proto__`, `constructor`, or `toString` is an ordinary own property, not a prototype collision. Unknown names, duplicate ids, and post-settlement messages are rejected or ignored — the port protocol assumes a hostile peer, because the peer runs model code.
5. **Enforce independent budgets.** `computeMs` meters worker busy time, allowing slow awaited tools without excusing a hot loop. `maxWallMs` bounds total elapsed time, including unresolved waits. Expiry, cancellation, and completion terminate the worker. Heap exits and truncation are reported explicitly; compute, wall, heap, log, and return-value caps are validated configuration.
6. **Dispose to quiescence**: the service's own disposal terminates in-flight workers and *awaits* their exits before resolving, per [defensive patterns](../../../defensive-patterns.md).
### Trust posture
The worker runtime provides containment, not a security boundary: model code can reach Node APIs and has authority comparable to the bash tool. `worker.terminate()` stops the thread but not OS processes it spawned. Code Mode uses the same `tools/pre-execute` policy gate as bash and adds an empty environment, heap limits, a separate isolate, and hard termination of the program itself. Deployments that need a hard multi-tenant boundary need a container-class backend for both code and bash; the runtime's isolation descriptor lets them distinguish that backend.
### What the model sees
The SDK instructs the model to write an async erasable-TypeScript body, call tools through `await tools.name(args)`, catch rejected tool calls when needed, and return or log only the output that should re-enter context. Calls remain sequential even under `Promise.all`. The declaration prefix can be as large as native schemas, especially in `'both'`, but remains stable for provider caching.
## Consequences
Deployments switching to `'code'` must update any native-only `toolOrder`. Assembly listeners own the integrity of any rewritten protocol surface. Sub-dispatch remains serialized, while per-call contexts retain their source, envelope, and metadata through the outer result.
## Testing
- **Worker runtime:** Real-worker tests cover output and value capture, failure kinds, compute and wall budgets, hostile binding traffic, empty environment, structured-clone fallback, output caps, and disposal to quiescence. A built-package test runs the worker entry under plain Node.
- **Registry integration:** Tests cover code generation, all presentation modes, reserved-name and restriction rules, scoped visibility, authoritative assembly rewrites, `toolOrder`, runtime compatibility failures, full-pipeline sub-dispatch, parent-token correlation, serialization, cancellation and queue drain, JSON normalization, error propagation, log events, ordered context deferral across successful and failed programs, outer-block suppression, and HMR cleanup.
- **With-key e2e:** A real model composes two bash calls in one program; another discovers nested workspace instructions through a Code Mode fs dispatch. The tests verify collapsed request headers, correlated dispatch events, resulting files, deferred context, and model behavior.
- **Snapshot:** The `code-mode-turn`, `both-mode-turn`, and `code-mode-workspace-context` fixtures pin SDK text, header tool lists, dispatch events, deferred context, and result cards.
## Alternatives considered
**An add-on consumer plugin with zero core changes.** Rejected because `agent/request` is call-config-only under [reconstructable requests](../../implemented/architecture/2026-07-05-reconstructable-requests.md), while transforming an assembled tool list would have to undo `toolOrder` canonicalization without owning its config and would depend on listener order. Which tools the model is offered, and in which representation, is the registry's single concern: native schemas and the SDK are two projections of one visible store.
**`node:vm` as the reference runtime, with hardening deferred.** Rejected: `node:vm` is not isolation (prototype-chain escapes reach the host realm) and cannot interrupt a hot loop. A worker thread provides a separate isolate, empty environment, `resourceLimits`, and reliable `terminate()` at bash-equivalent trust, so the reference and production implementation are one package without an unsafe-acknowledgement ceremony.
**Result elision / summarization over native tool-calling.** Addresses only the context-bloat half of the problem: trimming old `tool-result`s is cheap to add as a logged surface replacement under reconstructable requests, but still pays one model round-trip per call and cannot express loops, branches, or joins. Complementary, not competing; it can layer under Code Mode for residual native calls.
**Parallel native dispatch in the loop.** The other answer to round-trip cost; still valid future work (the open TODO), still blocked on concurrency-safety metadata, and still no composition — it parallelizes calls the model already decided on in one step. Code Mode's serialized-queue decision keeps the two compatible: when the metadata lands, both native parallel dispatch and per-tool binding parallelism unlock together.
**Always-exclusive (Cloudflare-faithful, no mode).** Rejected for this SDK's primary consumer: a coding agent's bread-and-butter single calls (`bash`, `read`, `edit`) are already ideal as native calls, and forcing every edit through a program taxes the common case. The mode config keeps the faithful form (`'code'`) one line away without imposing it.
**Per-tool visibility tiers (this tool native, that tool code-only).** Deferred: it needs per-tool metadata and a presentation split that `'native' | 'code' | 'both'` does not, and its design depends on evidence about how models split usage under `'both'`.
**Sanitized identifier aliases in the SDK** (`my-tool``my_tool`, Cloudflare's approach). Rejected: quoted keys on a `declare const` make every name reachable with zero alias-collision logic; models handle `tools["my-tool"](…)` fine.
**A REPL-style persistent kernel** (state survives across `run_code` calls). Rejected for the MVP: cross-call state would be invisible to the session log, breaking the reconstructability guarantee that every request is a pure function of the log; fresh-per-run keeps it. A kernel-style backend remains expressible behind the seam later, with its own logging story.
## Risks
**The worker is not a hard security boundary.** Deliberate and documented (§Trust posture): posture equals the existing bash tool, containment exceeds it, gating uses the same seams. Deployments needing more need a future `isolation: 'container'` backend — tracked as the seam's designed extension, not a TODO on this design.
**`stripTypeScriptTypes` is marked experimental.** It is the same engine (amaro/swc) behind Node's own native `.ts` execution, exposed as an API across this repo's whole engines range. Mitigations: the runtime's unit suite pins the behaviors relied on (position preservation, erasable-only rejection message shape loosely), the call sits behind one private function, and `amaro`/`sucrase` are drop-in replacements if the API shifts. The erasable-only subset is a model-facing contract line, and the error path is a working feedback loop, not a dead end.
**Prompt cost of the SDK, especially under `'both'`.** The `.d.ts` can rival the native schemas it complements; `'both'` carries two representations. Prefix stability + provider caching amortize per-session cost; the mode is per-deployment; the RFC makes no unconditional-savings claim. Measured guidance (when to prefer which mode) is explicitly post-ship learning.
**Registry scope growth.** `dsh-tools` absorbs codegen, a tool, a bridge, and an event. Contained by module boundaries inside the package (`ts-types.ts`, `code-mode.ts` beside `schema.ts`/`json-schema.ts`/`presentation.ts`) and by the seam: everything substrate-shaped lives behind `ctx.codeRuntime`.
**Structured-clone values can exceed JSON.** Tool bindings therefore JSON-normalize arguments before dispatch, ensuring every executed call can be logged. The lower-level runtime keeps its wider port contract, while stricter consumers validate at their boundary. Non-text sub-results become placeholders.
**Serialized-only sub-dispatch.** `Promise.all` gains no wall-clock parallelism yet, only fewer round-trips; models may over-expect. The instructions state it; lifting it is tied to the same concurrency-safety metadata the native parallel-dispatch TODO needs.
**Budget metering reads the event loop, not a flag.** Busy-time polling (`eventLoopUtilization()`) is coarser than an exact CPU meter — a budget expires up to one poll interval late — and its correctness claim ("a pending dispatch cannot pause it") is load-bearing against a hostile program. Both sides are unit-tested (hot loop with a pending decoy dispatch dies at `computeMs`; idle-on-slow-binding survives to `maxWallMs`), and the poll interval is an internal constant, not config — nothing a deployment could mis-tune into a bypass.

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@@ -4,9 +4,9 @@ Status: implemented
## Problem
The ACP bridge lets each tool own its call rendering via `presentCall`/`presentResult` (see [tool-call UI presentation](../../proposed/feature/2026-06-14-acp-agent-client-protocol.md) and `packages/core/tools`). For `bash` we surface the exact command as the `tool_call` title, the model's `description` as a content text block, `kind: 'execute'`, and the completed output wrapped in a fenced ` ```console ` text block.
The ACP bridge lets each tool own its call rendering via `presentCall`/`presentResult` (see [tool-call UI presentation](../../implemented/feature/2026-06-14-acp-agent-client-protocol.md) and `packages/core/tools`). For `bash` we surface the exact command as the `tool_call` title, the model's `description` as a content text block, `kind: 'execute'`, and the completed output wrapped in a fenced ` ```console ` text block.
That is a correct, capability-free baseline, but not how the reference editors render a *terminal* tool at its best. An editor like Zed has a dedicated terminal tool-call card — a header showing the working directory, the command as the label, the command output rendered as a terminal, and an exit-status pill — but it only builds that card when the `tool_call` carries terminal metadata (below). With a plain text block the output appears as static markdown and there is no cwd header. (Zed also HIDES `rawInput` for `kind: 'execute'`, which is why the command IS the title — both reference adapters do the same. The human-readable description rides as a separate content block above the card; note this is a DELIBERATE divergence — claude-agent-acp DROPS the description in terminal mode and renders only the card — we keep the summary visible alongside.)
Reference editors render terminal metadata as a dedicated card with cwd, command, live-style output, and exit status; plain text loses that structure. The command is the title because execute cards hide raw input, while the human-readable description remains a separate block above the card.
## Key finding: agent-executed terminals use a `_meta` convention, NOT `terminal/create`

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@@ -34,7 +34,7 @@ An earlier draft put the full algorithm (the retention walk, token-summing, text
### Auto-compaction runs on `agent/pre-step`, a dedicated surface-mutation seam
Compaction is a **surface mutation**, not a request transform — and that distinction is the seam it belongs on. The loop's request lifecycle, per step, is: assemble the system prompt → open the step → derive the message history from the surface → run the `agent/request` waterfall → call the model. An earlier cut wedged compaction into the `agent/request` waterfall, which forced two problems: (1) the loop had already derived `messages` from the *stale* surface, so the listener had to mutate the surface and then *re-derive* and overwrite `request.messages` — a double-derive whose only purpose was to undo the premature first derive; and (2) `agent/request` also carries downstream-injected context a listener might have added to `request.messages`, which compaction cannot act on (it can only compact the surface), inviting the confusion of measuring tokens compaction can't shed.
Compaction mutates the session surface, so it runs before the step opens and before messages are derived. `agent/request` remains a call-config transform and never needs to rebuild history after a surface change.
The fix is a dedicated loop seam, **`agent/pre-step`** (`@mode serial`), fired by the loop *after* system assembly and *before* the step opens (`step/start`):
@@ -46,15 +46,13 @@ messages = session.deriveMessages() ⟵ single derive, reflects the compaction
request = waterfall agent/request ⟵ pure request transform (hooks, model switch)
```
This makes the layering correct *by construction*: compaction mutates the surface, the loop derives **once** from the result (no double-derive), and at `pre-step` the assembled `messages` do not yet exist — so a listener structurally *cannot* see or be expected to act on downstream-injected context. `agent/request` reverts to a pure request transformer. Firing the seam **before** `step/start` (not inside the open step) is load-bearing for crash-safety: compaction's log-only `compact/*` records and its replacement node land *outside* any step, so the honest log structure a crash leaves (a dangling `compact/start` sitting before the synthetic `turn/end` that turn-repair appends) holds without a half-open step to reconcile. The seam is `serial` (awaited, in registration order), not `parallel`: a listener mutates the surface as a side effect — there is nothing to transform or return — and serial isolates listeners from each other so two surface-mutating listeners can never interleave their `session.append`s. Cordis `serial` does bail early if a listener returns a bail value, so `agent/pre-step` listeners are typed/documented to return `void` and must not use that bail channel as a semantic veto surface.
This **amends** the original RFC's claim of "NO changes to `dsh-agent-loop`; compaction is a pure plugin." That claim was load-bearing for a wrong design — reusing `agent/request` was the mistake. Per the pre-release "foundation over blast radius" stance, adding the correct seam (one event declaration in `dsh-agent`, one awaited emit in the loop) beats preserving a no-change boast that locked in the double-derive.
The loop derives messages once after `agent/pre-step`. Running before `step/start` keeps compaction records outside any half-open step, simplifying crash repair. The seam is awaited and serial so surface mutations cannot interleave; listeners return `void` and do not use Cordis bail values as vetoes.
### Retention is turn-agnostic; tool-pairing balance is the only structural guard
Auto-compaction fires before **every** step, not once per turn. This is **load-bearing for runaway-turn survival**: a tool-heavy ReAct turn appends an `assistant/message` + a `tool/result` per step, so the surface grows *within* a turn. A single turn can grow past the window on its own (a "runaway turn") — and the only moment to rescue it before the next model call overflows is the next step's `pre-step` checkpoint. Gating compaction to a turn's first step (or, worse, retaining the whole in-flight turn verbatim) re-opens exactly the hole compaction exists to close: the harness would die when compaction is most needed.
So retention does **not** protect the in-flight turn, and turn boundaries play no role in it. `compactIfNeeded` walks the surface nodes tail→head, summing per-node token estimates, and retains the smallest tail-run of **whole units** whose total reaches `retainTokens`; everything older is compacted (head-anchored — see below). A *unit* is either a whole closed step (its `assistant/message` plus its `tool/result`s) or a single no-step node (a pre-step `user/message`, inter-step `steering/message`, or injection `context/message`). The walk rounds toward retaining *more*: when the raw token cutoff lands mid-step, it extends the retained side head-ward until the cut before the retained node is **tool-pairing balanced**. The single structural guard is therefore **tool-pairing balance** — a region's edges are balanced cuts on the *surface* (no unanswered `tool-call` crosses either edge), so a compacted region never splits a step's tool-calls from their `tool/result`s (which would produce a transcript every provider rejects). The check is decided over the surface linked list, **not** the log's `step/*` markers: a compaction lands a replacement node at a high log seq whose surface position is the head, so a log-position scan mis-reads its neighbours — `dsh-session` exports `isToolPairingBalanced(nodes, events, beforeSeq)` for the surface-anchored check. `compactRegion` enforces it strictly, throwing on a boundary that would split a step.
`compactIfNeeded` retains the smallest tail of whole surface units whose estimated size reaches `retainTokens` and compacts older nodes. A unit is a complete closed step or one no-step message. If the token cutoff lands inside a step, retention expands until the cut is tool-pairing balanced. Balance is checked on surface order, not log sequence, because replacement summaries have new sequence numbers at old surface positions. `compactRegion` rejects boundaries that split a tool call from its result. The in-flight turn receives no special retention.
A runaway turn thus compacts exactly like any other history: its early *closed* steps get summarized while its recent steps stay verbatim. When the only compactable content left is an un-splittable open tail step (its tool-calls have no results yet), compaction declines (`null`) and retries once that step closes.
@@ -62,7 +60,7 @@ A runaway turn thus compacts exactly like any other history: its early *closed*
### Head-anchoring: one auto checkpoint, always at the head
`compactIfNeeded` always anchors the compacted range at the surface **head** (`nodes[0]`). After a first compaction lands a summary node at the head, the *second* compaction's range starts at that summary node and re-summarizes it together with the steps accumulated since — so the surface holds **at most one** auto-generated checkpoint, always at the head, re-consolidated each cycle (the backend's checkpoint-merge prompt makes this a cheap incremental merge — see below). This is *why* `CompactionResult.shadowedRange` is a **surface-position span, not a numeric seq interval**: after a replace lands a fresh high-seq summary node at an older range's position, `start` can be numerically **greater** than `end`. The range is resolved positionally (index into the ordered node list and slice), and `shadowedSeqs` is the authoritative set in surface order. (Manual `compactRegion` may target any aligned mid-range and so *can* leave several checkpoints; the checkpoint framing does not claim everything after it is recent.)
Auto-compaction always starts at the surface head, merging the prior checkpoint with newly compacted history so only one automatic checkpoint remains. `shadowedRange` is therefore positional rather than a numeric sequence interval: a newer summary sequence may occupy an older surface position. `shadowedSeqs` records the authoritative surface order. Manual mid-range compaction may leave multiple checkpoints.
### Approximate convergence invariant
@@ -85,7 +83,7 @@ compact/end → log-only. Releases the lock (carries `error` on a recoverab
### Checkpoint framing + incremental merge (backend-private)
The landed `user/message` is not the raw summary: the backend wraps it in a checkpoint preamble (so a resuming model reads it as established background, not a fresh request) and `<compacted-summary>…</compacted-summary>` tags. The tags make a prior checkpoint detectable on the next cycle, and the summarization prompt then instructs the model to *merge it in place* (preserve still-true facts, drop stale) rather than re-summarize verbatim — a cheap incremental merge that needs no extra log/event machinery. The raw, unframed summary stays on the `compact/summary` provenance event. This framing is entirely a **backend HOW decision** — the contract only promises "a single replace `user/message` carries the (possibly framed) summary; the raw summary lives on `compact/summary`." A template or remote backend may frame differently or not at all.
The basic backend wraps the summary as established checkpoint context and tags it for incremental merging on the next cycle. The raw summary remains on `compact/summary`. Framing is backend policy; the seam promises only that one replacement user message carries the possibly framed summary.
### Blocking via a log-recorded lock, plus a crash/recoverable failure taxonomy
@@ -121,7 +119,7 @@ Two failure paths, both documented:
## Testing
- **Unit** (`dsh-compact-basic`): the whole-unit retention walk, the convergence-invariant throw, both failure paths (`compact/end` with/without `error`), head-anchoring producing a non-monotonic `shadowedRange`, decline-on-open-tail, crash-orphan inertness, and the **runaway-turn regression** — a single oversized open turn compacts its early closed steps (proven to fail on the layer-2 protection it replaced). Driven through the real `dsh-invariants` plugin and the real Loader/inject path.
- **Loop** (`dsh-agent-loop`): `agent/pre-step` fires once per step, after `turn/start` and before `step/start`, awaited; a surface mutation in a `pre-step` listener lands outside the step and is reflected in the single derived request.
- **With-key e2e** (`examples/coding-agent`): a real model + real bash session with a lowered `contextWindow`/`retainTokens` triggers compaction mid-session; the test verifies the WORLD (a `compact/start…end` pair landed, the surface shrank, the agent still completed the task after compaction). This is compaction's first real-world exercise and the runaway-survival net.
- **Snapshot (deferred, named gap)**: a full-transcript snapshot of a runaway-turn compaction is NOT yet possible — `dsh-llm-replay` derives one model call per `(turn, step)` from `assistant/chunk` events, but the summarization call records no `assistant/chunk`s and carries no `sessionId` (it binds to the anonymous cursor and claims a non-existent extra script). Covering it needs net-new replay infrastructure (record/replay an interleaved summarization call) and is scheduled as a follow-up rather than discovered mid-build.
- **Unit:** Real Loader and invariant plugins cover whole-unit retention, convergence failure, both `compact/end` outcomes, head anchoring, open-tail refusal, inert crash orphans, and compacting closed steps inside one oversized open turn.
- **Loop:** Tests pin one awaited `agent/pre-step` per step between `turn/start` and `step/start`; a surface mutation there lands outside the step and appears in the single derived request.
- **With-key e2e:** A real model and bash session with lowered limits triggers compaction, records a complete `compact/start…end` pair, shrinks the surface, and finishes the task.
- **Snapshot gap:** Runaway-turn compaction cannot yet replay because the summarization call records no `assistant/chunk` events or `sessionId`; interleaved summarization-call replay remains follow-up work.

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@@ -35,18 +35,18 @@ A new package group `packages/subagent/`:
| `@deepseek-ai/dsh-subagent-mock` | support: a scripted provider for testing the seam through the real load path |
| `@deepseek-ai/dsh-tool-subagent` | consumer: the model-facing `subagent` tool over `ctx.subagents` |
### The primitive: `start → SubagentRun`
### The primitive: async `start → SubagentRun`
A provider exposes `start(request) → SubagentRun`. The run carries a `result` promise (the terminal `SubagentResult`), `cancel()`, and `dispose()`. The transport-neutral verb is **`start`**; "spawn" is reserved for the in-process `dsh-subagent-spawn` backend's identity, not the service verb. The service's `start(name, request)` resolves the named provider, validates capabilities, delegates, and emits `subagent/start` / `subagent/end` around the run.
A provider exposes `start(request) → Promise<SubagentRun>`. Fulfillment publishes a ready child and transfers its run handle to the caller. One signal covers cancellation before and after readiness; `dispose()` cancels remaining work and awaits quiescence. A rejected start cleans partial resources and emits no lifecycle event. `start` is transport-neutral; `spawn` names only the fresh in-process backend.
### Two kinds of optional capability, discovered two ways
- **Start-time features** (`outputSchema`, `depthLimit`, `toolFilter`) ride on a static `provider.capabilities` descriptor. The service checks every requested one BEFORE delegating and **rejects loud** (`SubagentError('UNSUPPORTED_CAPABILITY')`) if the provider lacks it — never accepted-then-ignored. They must be checked before a run exists, which is why they cannot be runtime methods.
- **Start-time features** (`outputSchema`, `depthLimit`, `toolFilter`, `persona`) ride on a static `provider.capabilities` descriptor. The service checks every requested one BEFORE delegating and **rejects loud** (`SubagentError('UNSUPPORTED_CAPABILITY')`) if the provider lacks it — never accepted-then-ignored. They must be checked before a run exists, which is why they cannot be runtime methods.
- **Runtime features** (steering via `sendMessage`, follow-up via `resume`) are **optional methods** on `SubagentRun`. The method's presence IS the capability, and TypeScript narrowing is the discovery mechanism: a consumer cannot call an absent method without narrowing first, so there is no silent-degradation path and no separate flags object to keep in sync.
### Fork vs. fresh are separate backends, not a flag
Rather than a `context: 'fresh' | 'fork'` request field, the distinction is the provider's identity: `dsh-subagent-spawn` (fresh, isolated, own system prompt) and `dsh-subagent-fork` (seeded from the parent's log) are two registered providers. You pick behavior by picking a provider — consistent with the registry being the selection mechanism. The fork backend seeds only a **balanced, completed-turn prefix** of the parent log: at tool-execute time the parent's turn is open (it holds the `assistant/message` and the dangling spawn `tool/call` with no `tool/result`), and seeding that raw prefix would give the child an unbalanced turn the [invariants](../../../../packages/support/invariants/src/index.ts) freeze-check rejects.
Fresh and forked children are separate providers, not a request flag. `dsh-subagent-spawn` starts an isolated child; `dsh-subagent-fork` seeds a balanced prefix containing only completed parent turns. The in-flight turn is excluded because its subagent call has no result yet and cannot form valid replay history.
### Child isolation and the parent log
@@ -54,7 +54,7 @@ Each subagent runs in its **own `Session`** (own id, `parentSession` lineage), p
### Synchronous collect (first cut)
The `dsh-tool-subagent` consumer awaits `run.result` and returns the child's final output as the tool result, blocking the parent's turn until the child finishes. It does so inside a `try/finally` that always `dispose()`s the run (no leaked idle child/session on any path), bridges `exec.signal` to `run.cancel()`, and maps a non-`completed` stop reason to an `isError` result rather than returning partial output as success. Steering (`sendMessage`) is part of the contract but **intentionally unused** this cut.
`dsh-tool-subagent` passes its execution signal to `start()`, awaits the child result, and disposes the run in `finally`. Non-completed outcomes become error results rather than successful partial output. This foreground consumer does not use the run's optional steering method.
### Provider selection is config, not model-facing
@@ -62,12 +62,11 @@ The `dsh-tool-subagent` consumer awaits `run.result` and returns the child's fin
## Testing
The seam is tested through the real cordis Loader / export path, not a hand-built `ctx.plugin` mount (which bypasses `unwrapExports` and cannot catch a broken export shape — [postmortem 0001](../../../postmortem/0001-acp-default-export-drops-inject.md)); the registry pins HMR-safety, duplicate-name rejection, and start-time capability rejection; the nested-agent snapshot scenarios replay keyless in the default gate ([per-session snapshot replay](../testing/2026-06-22-subagent-snapshot-replay.md)); in-process backends carry real-loop unit tests plus a with-key e2e.
The seam is tested through the real Cordis Loader/export path, which catches the export-shape failure described in [postmortem 0001](../../../postmortem/0001-acp-default-export-drops-inject.md). Registry tests cover reload safety, duplicate names, and start-time capability rejection; nested-agent scenarios replay keylessly through [per-session snapshot replay](../testing/2026-06-22-subagent-snapshot-replay.md); in-process backends also have real-loop unit tests and a with-key e2e.
## Consequences
- **Recursion.** Without a guard, an in-process child inherits the spawn tool and can spawn unboundedly. Depth-limit is an optional capability (the in-process backends enforce it; ACP advertises it off and rejects a `maxDepth` request); tool-filtering is likewise optional. Tool-filtering, when implemented, needs a `tools/pre-execute` deny in the child context — schema filtering alone is insufficient because a model can hallucinate a denied tool name.
- **Blocking the parent turn.** Synchronous collect holds the parent's `runStep` open for the child's full duration. This is acceptable for the first cut; **background / poll / spill semantics are deferred to a future redesign that unifies long-running-tool handling across subagents AND bash** (a sub-agent and a long `bash` background task pose the same "the model started something slow, how does it collect later" problem, and should share one mechanism rather than each inventing its own).
- **Recursion.** Without a bound, an in-process child can see the delegation tool and recurse. The in-process backends implement the optional absolute depth limit and scoped live-global `toolFilter`; ACP advertises both capabilities off and rejects such a request. The [subagent composition-controls RFC](2026-07-12-subagent-persona-tool-filter-and-depth.md) owns their exact semantics and security limits.
- **Blocking the parent turn.** Foreground collection holds the parent's step open for the child's full duration. Background delegation uses the shared `ctx.tasks` runtime and generic `task_*` tools, the same collection mechanism as background bash; the subagent seam itself remains task-agnostic.
- **Live progress.** This cut surfaces only lifecycle + final result; a per-chunk child→parent update stream is deferred with the background redesign.
- **ACP client surface.** Proxying `fs`/`terminal` from the ACP child back to the parent (a shared-workspace mode) is future work; the first cut advertises neither, so the child self-serves in its own process.
- **Snapshot coverage of nested agents.** The snapshot tier (`pnpm run test:snapshot`) replays a recorded session through `dsh-llm-replay`. It was built single-session: a single GLOBAL positional cursor (the Nth `llm/stream` call serves the Nth recorded entry) and a harness that harvested a single session log file. A subagent runs as a *second* agent with its own session log, so a parent→child scenario needed per-session-keyed replay plus harvest-all-logs and plural-session-id plumbing — self-contained infrastructure orthogonal to the backends, scheduled as a dedicated stacked follow-up rather than folded into the in-process-backends PR. That follow-up has **landed**: see [Per-session snapshot replay for nested agents](../../implemented/testing/2026-06-22-subagent-snapshot-replay.md). Replay now keys each call by its calling session (`GenerateOptions.sessionId`) and binds live sessions to recorded scripts by first-call order; the harness harvests every log; and two nested scenarios (`subagent-spawn`, `subagent-multi`) replay keyless in the default gate. In-process subagents remain covered by real-loop unit tests and a with-key e2e in addition to the snapshot tier.

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@@ -32,17 +32,15 @@ The child is a separate process, so it inherits an environment. Credential-shape
## Testing
Designed at every tier the backend touches, per the root AGENTS.md rule that a new capability shape names its coverage at every tier at plan time:
- **Keyless unit/integration** (`subagent-acp.spec.ts`): spawns a scripted mock ACP server subprocess (`tests/mock-acp-server.ts`) and drives it through the real backend over real ACP stdio. Covers: the prompt round-trip + output accumulation; every StopReason mapping; cancellation via `run.cancel()` and via the request signal; the already-aborted-before-start case; the cancel-races-ahead-of-newSession case; a torn-pipe-after-cancel (child crashes on cancel) settling `aborted`; permission auto-answer under both policies (including the allow-policy-no-allow-option fallback); a non-message update consumed but not accumulated; a nonexistent-command spawn failure settling `error`; HMR provider cleanup; and the namespace export shape. 100% per-file coverage.
- **With-key e2e** (`subagent-acp.e2e.ts`): the harness drives ITSELF — the backend spawns the real `acp-agent` example process and a real model in that child answers a prompt (PONG) and does real file work (writes `proof.txt`, verified on disk). Self-skips without `DEEPSEEK_API_KEY`. This is the "talk to our own process" smoke and the out-of-process analogue of the in-process spawn e2e.
- **Snapshot**: deferred as `TODO(acp-subagent-replay)`. An ACP child is a distinct replay shape — each child is its own PROCESS with its own single-agent replay (booted under `DSH_SNAPSHOT=replay` with its own sessions-root + fixture), unlike the in-process per-session keying that [the per-session replay RFC](../testing/2026-06-22-subagent-snapshot-replay.md) added. The keyless mock-server tests give deterministic coverage of the backend in the meantime; the snapshot follow-up would record the parent driving a real-but-replayed ACP child.
- **Keyless unit/integration:** A scripted ACP subprocess exercises real stdio for prompt/output flow, every stop-reason mapping, signal and disposal cancellation (including pre-abort, pre-session race, and torn-pipe cases), both permission policies, ignored non-message updates, missing-command cleanup, provider reload, and namespace exports.
- **With-key e2e:** The backend spawns the real ACP example; its model answers `PONG`, writes `proof.txt`, and the parent verifies the file.
- **Snapshot gap:** Each ACP child is a separate process with its own replay session, unlike in-process per-session replay. Deterministic mock-server coverage exists, while `TODO(acp-subagent-replay)` tracks parent replay against a replaying child.
## Alternatives considered
### Why not the 0.28.x SDK bump?
### Why stay on SDK 0.25.1?
The plan proposed bumping `@agentclientprotocol/sdk` 0.25.1 → 0.28.x for the new fluent `acp.client()` / `ActiveSession.nextUpdate()` API. Validating that against the code (the AGENTS.md "RFC is a proposal, not golden truth" discipline) reversed the decision: the backend only needs `ClientSideConnection` + `ndJsonStream` + `PROTOCOL_VERSION` + the `Client`/`Agent`/`StopReason` types, **all present and non-deprecated in 0.25.1**. The fluent API and `unstable_forkSession` that motivated the bump are never used here, so the "cleaner client code" benefit did not materialize. Worse, 0.28.x **deprecates both** `ClientSideConnection` AND `AgentSideConnection` (it wants all callers on the fluent builders), which turns the `no-deprecated` lint red across the entire existing ACP layer — 33 usages including the server bridge this backend has no business rewriting. That cross-cutting connection-API migration is its own change, not baggage for "add an ACP subagent backend". So the bump was reverted and the backend is written against 0.25.1 (the plan's own fallback clause: "if the bump proves disruptive, fall back to `ClientSideConnection` (0.25.1), which is sufficient"). Migrating the whole ACP layer to the fluent API on a later 0.28.x bump is a worthwhile standalone follow-up.
The backend needs only `ClientSideConnection`, `ndJsonStream`, `PROTOCOL_VERSION`, and the client protocol types, all supported in 0.25.1. The 0.28 fluent API would require migrating both client and server connection classes across the ACP layer without improving this backend, so that upgrade remains a separate change.
### Why not a persistent child process?

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@@ -0,0 +1,87 @@
# RFC: Workspace context instruction files
Status: implemented
## Problem
Repository guidance such as `AGENTS.md` belongs in a coding session's effective context so project conventions, build commands, and review rules arrive without repeated user pasting. The stdio and ACP products need the same behavior, isolated by session cwd: a global system-prompt section leaks one workspace's files into another live ACP session.
Neighboring products establish useful conventions but differ in details. Codex treats `AGENTS.md` as native, Claude Code uses `CLAUDE.md` and familiar system-reminder-style user context, and opencode supports both names with one winner per directory plus lazy nested discovery. The harness needs cross-tool compatibility without loading duplicate or contradictory files from the same scope.
The lifecycle has two distinct classes of content. The initial applicable chain is stable enough to live in the request prefix and benefit from provider prefix caching. Nested files, edits, candidate switches, and removals happen after the session starts and belong in durable append-only history rather than the frozen prefix.
## Decision
The implementation lives in `packages/context/workspace-context` as `@deepseek-ai/dsh-workspace-context`. It is a request-context extension, not a core service or a filesystem backend. `@deepseek-ai/dsh-agent-core` mounts it for both product front doors and forwards its config. The plugin consumes `agent/session-prefix`, `tools/post-execute`, and the optional `ctx.fs` capability.
The plugin does not statically inject `fs`. Providerless product trees therefore boot normally and the plugin no-ops until a filesystem provider exists. All production reads go through that provider. Candidate probes call `lstat` before `resolve`, so a repository-owned final-component symlink is rejected rather than followed outside the workspace. The session-prefix signal and dynamic tool execution signal propagate through resolution, metadata probes, and streaming reads, so cancellation does not wait for an unrelated filesystem scan. Once `lstat` identifies a regular-file winner, a provider exception or disagreement during resolve/stat is classified as unavailable: it is neither interpreted as a deletion nor allowed to fall through to a lower-priority candidate.
### File Names And Precedence
The default per-directory candidate list is `['AGENTS.md', 'CLAUDE.md']`. The list is configurable as `instructionFileCandidates`, and `AGENTS.md` is an ordinary first candidate rather than a hidden priority. In one directory, only the first existing regular-file candidate loads. With defaults, `AGENTS.md` is native and `CLAUDE.md` is a compatibility fallback.
Candidate entries are same-directory file names. Empty entries, `.`/`..`, and entries containing `/` or `\` are ignored. Lowercase names, local variants, and other same-directory names can be opted into explicitly; rule directories and import semantics are outside this contract.
The user-global file is fixed at `$DSH_HOME/AGENTS.md` and is not affected by `instructionFileCandidates`. `$DSH_HOME` defaults to `~/.dsh`, matching the harness-level home role of `~/.codex` or `~/.claude` rather than introducing a plugin-specific home. Tilde expansion and the default live in `dsh-paths` so future harness features share the same convention.
### Baseline Prefix
On the first request of an agent-loop instance, the plugin contributes one user-role message through `agent/session-prefix`. It loads the user-global file first, then finds the project root by walking upward from `agent.session.header.cwd` to a configured root marker (default `.git`), then loads one candidate from each directory from the root to the cwd. A `.git` file and a `.git` directory are both valid markers, covering linked worktrees and submodules. Without a marker, the cwd itself is the root.
The plugin prepends its contribution before `await next()` returns, so session-prefix contributions appear in plugin registration order. In the product spine workspace instructions are registered before a skills catalog and therefore appear first. The loop deep-freezes the composed prefix, logs it in `EpochHeader.messagePrefix`, and reuses it verbatim for that instance. It is request state, not `Session.deriveMessages()` history.
A resumed agent creates a new loop instance and recomposes the baseline from current files, with the new prefix anchored by the resume request header. This permits current baseline content on resume without mutating a prefix already used by an earlier instance.
The baseline is a user-role `<system-reminder>` with `Instructions from: <path>` sections and explicit authority and precedence language. This familiar model-facing frame avoids a harness-specific XML vocabulary. Project paths are root-relative and the user-global path is `~/.dsh/AGENTS.md` for the default home or `$DSH_HOME/AGENTS.md` for a configured home. A literal `</system-reminder>` inside file content is escaped. The package README owns the exact current [prompt shape](../../../../packages/context/workspace-context/README.md#prompt-shape).
### Dynamic Discovery And Refresh
After a successful first-party `read`, `write`, or `edit` call, the `tools/post-execute` listener reconciles the touched descendant chain and every scope already known to the session. A newly reached scope is returned through `additionalContexts` for the next request using an `Additional instructions from: <path>` system-reminder. Under Code Mode, `run_code` defers sub-dispatch contexts onto its outer result, so the same update is appended only after the parent result rather than being injected mid-call.
A content edit appends `Updated instructions from: <path>`, states that the new content replaces the previous content, and includes the complete current file. If precedence changes from one candidate to another, the message also names the previous path and says it no longer applies. If no candidate remains, the plugin appends `Instructions removed: <path>` and states that the previously loaded instructions no longer apply.
Dynamic messages use a raw `context/message` envelope because the plugin owns the complete system-reminder framing. Core context injection therefore supports `envelope: 'raw'`; callers that omit it retain the canonical `<context source="...">` wrapper. `context/message.meta` carries opaque JSON state that is persisted but never rendered to the model.
Shell commands are not discovery triggers. Local bash calls start fresh shells, and inferring reached paths from arbitrary command strings would require shell semantics the prompt plugin does not own.
### Duplicate Suppression And Change Detection
Every dynamic workspace context event stores versioned metadata with `{ action, scope, path, previousPath?, digest? }`, where `digest` is SHA-1 over the loaded content. The model-facing prompt has no HTML comments, hidden markers, or headings that are parsed back into state.
At reconciliation time the plugin scans plugin-owned `context/message` events and derives the latest state for each visible scope. A short per-session pending map begins only after the immutable top-level `tools/result` proves an `additionalContexts` entry survived every post-execute listener, then covers the interval before the loop appends that context to the log. Each entry records the open `{ turn, step }`: an equal durable `context/message` at or after its sequence boundary confirms and removes it, while a matching `step/end` arriving first means the loop discarded its context buffer, so the plugin removes both the pending entry and its version-cache fast path. A nested Code Mode result stages its changes under the parent's opaque execution token so repeated sub-dispatches in one run do not duplicate them; the parent result rolls that provisional state back and commits only contexts retained by outer policy.
An unchanged path and digest is suppressed. A logged removal is a tombstone, so a reappearing candidate becomes a new `set`. Resume works from persisted metadata. If compaction removes an instruction event from the visible surface, that state no longer suppresses a later load, matching the fact that the model can no longer see it. Only changes actually included under the byte budget enter metadata or pending state, so an omitted file remains eligible on a later touch.
The frozen baseline keeps an in-memory path/digest map for comparison. A later successful filesystem touch appends baseline edits or removals as dynamic messages; it never rewrites the prefix. During resumed prefix composition the plugin also reconciles visible dynamic scopes, so nested changes made while the agent was offline can append an update before the first resumed request.
There is intentionally no watcher. Detection occurs at the next successful structured filesystem touch or resumed prefix composition. A provider failure produces no removal; absence is only accepted when all configured candidates in that scope were probed successfully.
### Byte Budget And Bounded Reads
`maxBytes` is required and applies separately to a rendered baseline or one dynamic reconciliation batch; there is no implicit or unbounded render budget. Non-positive and non-finite values disable loading. When content exceeds the budget, broader files are omitted before the most-specific file is truncated. A visible `Workspace instruction budget ...` notice names omitted and truncated paths and byte counts, and output never exceeds the configured bytes.
`maxSourceBytes` is a positive per-file cap with a 1 MiB default. The loader checks reported size before reading and still consumes content through `streamText()` with a running UTF-8 byte count, so missing/stale metadata cannot force an unbounded allocation. An oversized winning candidate is unavailable rather than a reason to fall through to another same-directory name. The plugin deliberately keeps no process-wide cache and never retains instruction prose. It keeps only `{ path, version, digest }` per effective scope in a `WeakMap<Session, Map<scope, state>>`: a matching provider `FsVersion` plus matching effective prompt state skips the read, while a changed version triggers a bounded read and SHA-1 confirmation. SHA-1 remains the cross-provider content identity persisted in visible structured metadata; provider versions are only an in-memory invalidation fast path. Cache transitions for model-visible changes commit only when the corresponding context survives the complete tool-result policy chain, and are invalidated if that accepted context is later dropped with its aborted step before reaching the log.
## Alternatives considered
**Use a global `ctx.systemPrompt.section()`.** Rejected because one Cordis context can host sessions with different cwd values, while repository-owned text is lower-authority context rather than top-authority provider system content.
**Inject the baseline on every `agent/pre-step`.** Rejected because repeated history injection wastes tokens, complicates duplicate state, and prevents a structurally stable provider prefix. Prefix composition gives a frozen, logged, per-instance baseline while dynamic append-only messages handle changes.
**Load both `AGENTS.md` and `CLAUDE.md` in one directory.** Rejected because repositories in transition commonly duplicate guidance across both files. Ordered candidates make precedence explicit and configurable.
**Parse rendered headings or hidden comments to recover loaded state.** Rejected because instruction prose can contain the same text, causing silent false positives. Persisted JSON metadata provides an unambiguous state channel that is invisible to the model.
**Summarize files with a model.** Rejected because instruction files are already curated summaries; another model call is nondeterministic and can erase edge-case requirements. Deterministic full text with byte budgeting is simpler.
## Consequences
Workspace guidance is isolated per session and shared by both product front doors and every tool presentation mode. Initial instructions benefit from stable prefix caching, while nested and changed content remains durable and replayable. The generic session/agent context contract includes optional raw framing and JSON metadata, both propagated through prompt-submit and post-tool `additionalContexts` arrays without flattening entries.
Repository text remains untrusted input. Lower-authority user-role framing, explicit precedence language, delimiter escaping, and symlink rejection reduce risk but do not eliminate prompt injection. Permission and sandbox layers treat workspace files as data rather than authority.
The system is event-driven rather than watch-driven. Edits are not visible at the exact filesystem mutation instant unless that mutation goes through a structured tool; externally changed files are noticed on the next successful structured touch or resume. This keeps the design deterministic and provider-neutral.
## Deferred
Bash-derived path reporting, recursive startup scans, file watchers, lowercase defaults, `.claude/CLAUDE.md`, `.claude/rules/*.md`, import directives, ACP `additionalDirectories`, trust acknowledgements, and model-generated summaries are deferred. Same-directory private variants can be configured today; directory rule systems and imports need their own precedence and trust designs.

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@@ -0,0 +1,49 @@
# RFC: Ask-user question capability
Status: implemented
## Problem
The agent sometimes cannot proceed safely from model inference alone: it needs the human to choose a path, confirm a risky/default action, or provide missing information. Before this change, the only way to get that answer was for the model to ask in assistant text and then stop, which broke the normal tool-call loop: the agent had no structured way to pause, no option metadata for UIs, no abort/error taxonomy, and no way for non-stdio front doors to present the question consistently.
This is a user-facing capability, but it also crosses package boundaries. A model-facing tool needs a provider-neutral request vocabulary; each UI surface needs to decide how to show and collect the answer; the agent loop should remain unchanged because a tool call already has the right async shape.
## Decision
Introduce `dsh-user-interaction` as the provider-neutral interface package for `ctx.userInteraction`, colocated with the model-facing consumer `dsh-tool-ask-user` under `packages/ui`. The grouping is intentional: asking a human is a UI-backed product affordance, not part of the providerless core spine. The seam still owns the stable request/answer/error vocabulary, while UI product surfaces provide the concrete provider that collects the answer. The tool registers `ask_user_question`, forwards `{ questions, agent, signal }`, and returns the provider-computed structured answers as the tool result.
The model-facing request vocabulary is deliberately aligned with the product-research schema: `ask_user_question({ questions: [{ id, question, header?, options?: [{ label, description? }], multi_select? }] })`. `id` is supplied per question and echoed in the result so a batch can be routed without relying on question text. `label` is both user-facing display text and the selected value returned to the model; there is no separate `value`, no `recommended`, no `allow_custom`, and no `desc` alias.
Providers return `{ answers: [{ id, selected, custom? }] }`. `selected` is always an array of selected option labels, so single-select and `multi_select` answers share one result shape. `custom` carries a free-text "Other" answer; optionless questions collect `custom` directly. When `custom` is present, it overrides any selected choices and `selected` is empty.
`UserInteractionError` extends `HarnessError`, so failures such as `NO_PROVIDER`, `ASK_ABORTED`, ACP cancellation, or missing session routing survive `ctx.tools.execute()` as machine-routable `{ name, code }` tool errors. This matches the structured-error taxonomy and lets the model or a wrapping plugin distinguish "user cancelled" from a generic thrown exception.
## UI mappings
`dsh-stdio-demo`'s in-package readline module renders each question, shows each option's `description` on the next line, supports comma/space-separated numeric choices for `multi_select`, accepts free-form custom answers, and rejects pending questions on abort, provider disposal, or stdin EOF. A batched request is asked in order and resolved as one answer object. The stdio provider serializes simultaneous requests with an internal queue so only one prompt owns stdin at a time.
`dsh-acp` provides the same seam for ACP sessions. It routes an ask request from the calling `Agent` through the bridge's `agent→sessionId` reverse map and calls ACP `unstable_createElicitation` with a session-scoped form for each question. Single-select options become a `choice` string enum; `multi_select` options become a `choice` array enum; optionless questions use a required `custom` text field. If the client returns both `choice` and non-empty `custom`, the custom answer wins. ACP `decline`/`cancel`, a missing answer, a missing session, and a client without elicitation support all become structured `UserInteractionError`s.
The ACP mapping deliberately uses elicitation, not `session/request_permission`. `request_permission` is still reserved for the separate permission gate: it is a yes/no-or-policy authorization protocol around tool execution. `ask_user_question` is a general information-gathering tool with optional free-form answers, so ACP form elicitation is the closer protocol fit. The bridge's session routing is shared with the future permission gate, but the user intent is different.
## Alternatives considered
**Assistant text followed by a stopped turn.** The model could ask the user in plain assistant text and then stop. That loses the structured option metadata, gives UIs no provider-neutral way to render a choice, and forces the next human answer to arrive as a new user prompt rather than as the result of the operation that needed the answer.
**Core-owned ask-user packages.** The first implementation split the seam and the model-facing tool across `packages/core` and `packages/ui`, but both names describe one UI-backed human-interaction affordance. The seam remains provider-neutral, but it is not providerless core infrastructure like sessions, tools, or the agent registry. Keeping `dsh-user-interaction` and `dsh-tool-ask-user` together under `packages/ui` makes the package map match the product boundary: apps and bridges provide the human-answer provider, and the stdio app opts into the model-facing tool.
**ACP `session/request_permission`.** Permission requests are authorization around tool execution; `ask_user_question` is information gathering with optional free-form answers. Using permission for general questions would collapse two different product concepts and make the future permission gate harder to reason about.
**A loop-level pause primitive.** The agent loop already knows how to await a tool call and resume from a tool result. Adding a new loop special case would duplicate that async shape and make every loop implementation learn about a UI concern.
## Consequences
ACP elicitation is currently marked unstable in the SDK. The fallback is still structured: if a client does not implement it, the tool returns `ASK_FAILED` rather than hanging. A later ACP stabilization may rename or reshape the method; that migration should stay inside `dsh-acp` because the core `ctx.userInteraction` vocabulary is provider-neutral.
The feature gives the model a powerful pause primitive, so prompt guidance matters. The tool description tells the model to ask concise questions and use options when possible. Product policy can later wrap `tools/execute` to restrict when the tool is allowed, but the loop should not special-case it.
`dsh-user-interaction` and `dsh-tool-ask-user` both live in `packages/ui` because they form one product-facing human-interaction capability. `agent-core` does not load either the tool or a provider. `stdio-agent` opts into the seam, its readline provider, and the model-facing tool. `acp-agent` keeps only the `userInteraction` seam/provider by default: ACP elicitation support is still client-dependent, so an ACP leaf must opt into the model-facing tool deliberately once its client can complete elicitation requests.
## Testing
Unit coverage pins provider registration/disposal, duplicate-provider rejection, abort-before-provider, empty-question rejection, structured tool errors through `ctx.tools.execute()`, batched answers, multi-select answers, custom answers, and the model schema including the removal of `value`, `recommended`, `allow_custom`, and `desc`. `dsh-stdio-demo` tests cover option descriptions, queued requests, EOF/abort cleanup, optionless free-form input, invalid option reprompts, duplicate multi-select numbers, and batched question flows. ACP bridge tests drive a real in-memory ACP connection with the real `ask_user_question` tool and verify selected-option, custom-overrides-choice, multi-select, and optionless free-form elicitation paths continue the agent loop.

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@@ -32,7 +32,7 @@ claude-code V1's item is `{ content, status, activeForm }`; later (V2) it grew i
### Single owner — no swarm machinery (YAGNI)
The list belongs to the ONE agent session that called the tool (`exec.agent.session`); a non-agent caller is rejected. There is deliberately no shared/multi-owner scope, no capability seam (interface/impl/consumer), no scope resolver, and no delta protocol. The harness does have subagents, and a shared cross-agent list is conceivable — but building that now means designing for a form the product does not yet have. The whole-list-replace + single-owner shape is what claude-code V1, opencode, and codex all ship; if a shared list is ever needed, the on-log representation would change to per-item deltas (so concurrent writers can't clobber each other) and a scope resolver would choose the target log. That is a future RFC, not speculative scaffolding today.
Each list belongs to the calling agent session, and non-agent calls are rejected. There is no shared scope, resolver, or delta protocol. Cross-agent lists would require per-item log deltas and explicit scope selection, so they remain a separate future design.
### Validation: the cheap middle

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@@ -6,14 +6,14 @@ Status: implemented
The harness's extension surface is its typed interception seams ([the interception-seams RFC](2026-06-30-interception-seams.md)): a "native hook" is just an ordinary cordis plugin subscribing to `agent/session-start`, `agent/prompt-submit`, `tools/pre-execute`, `tools/post-execute`, `agent/turn-continuation`, `subagent/start`, `subagent/end`. But users arrive with **existing** Claude Code (CC) and Codex hook configs — a `hooks.json` (or a settings file's `hooks` key) full of shell-command hooks — and want those to run unmodified. This RFC introduces the two **bridge plugins** that translate that external shell-hook protocol onto the typed seams, built on the shared wire-protocol library ([the hook-protocol-lib RFC](2026-06-30-hook-protocol-lib.md)).
The framing that shapes the whole design: **a bridge is a faithfulness adapter, not a power tool.** Anything a bridge does (block a tool, inject context, force continuation, observe a subagent) a native cordis plugin does more powerfully — typed returns, full `ctx`, no serialization boundary. The bridge's only reason to exist is to run an UNMODIFIED external CC/Codex hook with byte-faithful semantics. That keeps each bridge thin: parse the config, pick a matcher mode, build the per-event payload, call `runHook` + `mergeHookOutputs` from the shared lib, map the neutral outcome onto a seam Decision.
The framing that shapes the whole design: **a bridge is a compatibility adapter, not a power tool.** Anything a bridge does (block a tool, inject context, force continuation, observe a subagent) a native cordis plugin does more powerfully — typed returns, full `ctx`, no serialization boundary. The bridge's reason to exist is to run the explicitly supported subset of external CC/Codex command hooks. That keeps each bridge thin: parse the config, pick a matcher mode, build the per-event payload, call `runHook` + `mergeHookOutputs` from the shared lib, and map the neutral outcome onto a seam Decision. The package READMEs own the exact current unsupported-event and partial-field inventory against the official protocols.
## Decision
Two independent plugins in the `packages/hooks/` group, each a function/namespace plugin (`name`/`inject`/`Config`/`apply`, NO default export — see [postmortem 0001](../../../postmortem/0001-acp-default-export-drops-inject.md)) injecting only `bash`:
- **`dsh-hooks-claude`** — the CC dialect. Seven hook points: `SessionStart`, `UserPromptSubmit`, `PreToolUse`, `PostToolUse`, `Stop`, `SubagentStart`, `SubagentStop`. Owns CC's per-event stdin payloads (a base of `session_id`/`cwd`/`hook_event_name` plus per-event fields), CC's env + `${CLAUDE_PLUGIN_ROOT}`/`${CLAUDE_PROJECT_DIR}` substitution, and the literal-or-regex matcher mode. A CC hook's stdin carries a **trailing newline**.
- **`dsh-hooks-codex`** — the Codex dialect: a deliberate SUBSET. Five hook points (`PreToolUse`, `PostToolUse`, `SessionStart`, `UserPromptSubmit`, `Stop` — no subagent/notification/compaction), an always-regex matcher, snake_case payloads with `turn_id`/`model`/`permission_mode` extras written WITHOUT a trailing newline, no env and no `${…}` substitution, and a block-only decision model (a Codex hook can never pre-approve, so `allow`/`ask` are not honored). A tool call's payload carries the real `tool_name` (the value the matcher tests, so a config's tool matcher fires) in Codex's `tool_input: { command }` shape.
- **`dsh-hooks-claude`** — the CC dialect. Seven of Claude Code's current hook points: `SessionStart`, `UserPromptSubmit`, `PreToolUse`, `PostToolUse`, `Stop`, `SubagentStart`, and `SubagentStop`. Owns CC-shaped per-event stdin payloads (a base of `session_id`/`transcript_path`/`cwd`/`hook_event_name` plus per-event fields), `CLAUDE_PROJECT_DIR` plus `${CLAUDE_PLUGIN_ROOT}`/`${CLAUDE_PROJECT_DIR}` substitution, and the literal-or-regex matcher mode. `transcript_path` is the persistence locator result or `''`; stdin carries a **trailing newline**.
- **`dsh-hooks-codex`** — five of Codex's current hook points: `PreToolUse`, `PostToolUse`, `SessionStart`, `UserPromptSubmit`, and `Stop`. It uses an always-regex matcher, Codex-shaped snake_case payloads with `turn_id`/`model`/`permission_mode` extras written WITHOUT a trailing newline, no Codex plugin-env injection or config-time placeholder substitution, and no pre-tool approval or rewrite path. `transcript_path` is the same locator result or `null`; tool payloads carry the real `tool_name` in the reduced `tool_input: { command }` shape.
### Outcome → Decision mapping
@@ -26,16 +26,18 @@ Each bridge maps the neutral `MergedHookOutcome` from the shared lib onto the se
| `tools/pre-execute` | `deny``deny`; `ask``ask` | `block``deny` (no allow/ask) |
| `tools/post-execute` | `deny``block`+feedback; context-only→delegate+fold | same |
| `agent/turn-continuation` | blocking Stop → `continue` (reason = next-step steering) | same |
| `subagent/start` (emit) | additionalContext → inject into the live child | — (not a Codex event) |
| `subagent/end` (emit) | observe-only | |
| `subagent/start` (emit) | additionalContext → inject into a live in-process child; a remote child has no local injection target | unsupported by this bridge |
| `subagent/end` (emit) | observe-only | unsupported by this bridge |
The CC bridge's `ask` result is a real permission path, not a terminal bridge decision: `dsh-tools` resolves it through the optional [approval seam](2026-07-06-approval-seam.md). A composed ACP answerer prompts the owning editor session and `allowed-once` proceeds; without an ApprovalService or answerer, the call fails closed to `deny`.
### Context source is always the plugin (the mislabel guard)
`agent.inject()` defaults a missing `MessageSource` to `{ kind: 'user' }` — which would record plugin-injected context as if the user had typed it. So every bridge `inject()` and every `HookContext` passes an explicit `{ kind: 'plugin', plugin: 'hooks-claude' | 'hooks-codex' }` source. A test asserts the resulting `context/message.source` is the plugin, never `user`.
`agent.inject()` defaults a missing `MessageSource` to `{ kind: 'user' }`, so every bridge `inject()` and `HookContext` passes `{ kind: 'plugin', plugin: 'hooks-claude' | 'hooks-codex' }`. Unit coverage pins the resulting `context/message.source` as the plugin rather than the user.
### Adding context is not a veto — delegate, then fold
### Adding context is not a veto — delegate, then prepend
A hook that only attaches `additionalContext` (no block/deny) is NOT a decision the bridge should return on its own: returning `allow`/`accept` from a waterfall listener WITHOUT calling `next()` short-circuits every later `agent/prompt-submit` / `tools/post-execute` listener, so a policy/sandbox plugin registered after the bridge would never see the prompt. So on the context-only path each bridge **delegates via `next()`** and then **folds** its `additionalContext` onto the downstream decision (`concatContext`). The fold differs by seam because the two Decision unions differ: `tools/post-execute` — a downstream `block`/`accept` both carry an `additionalContext` field, so the bridge context rides along either way (a downstream block wins AND keeps the context; a downstream accept keeps its content rewrite and gains the context). `agent/prompt-submit` — a downstream `allow` gains the bridge context (and keeps its own content rewrite / additionalContext), but `PromptDecision.block` carries no context field, so a downstream block drops the bridge context — which is correct: a blocked prompt never reaches the model, so context attached to it is moot. Only a real `deny`/`block` from the hook itself short-circuits. Tests assert a later listener can still block a prompt a context-only hook allowed, and that both contexts survive when the downstream also adds one.
A hook that only attaches `additionalContext` (no block/deny) is NOT a decision the bridge should return on its own: returning `allow`/`accept` from a waterfall listener WITHOUT calling `next()` short-circuits every later `agent/prompt-submit` / `tools/post-execute` listener, so a policy/sandbox plugin registered after the bridge would never see the prompt. Each bridge therefore delegates via `next()` before adding its context to the downstream decision. Both seams carry ordered `additionalContexts` arrays, so the bridge prepends its separately sourced entry while preserving every downstream source, envelope, and metadata field; a downstream prompt block still drops all context because the prompt never reaches the model, while post-tool block semantics may explicitly retain contexts. Code Mode ferries the same array through the outer `run_code` result. Only a real `deny`/`block` from the hook itself short-circuits. Tests assert a later listener can still block a prompt a context-only hook allowed and that retained prompt and post-tool contexts remain separate.
### CLAUDE_PROJECT_DIR defaults to the session workspace
@@ -43,20 +45,19 @@ Claude Code always exports `CLAUDE_PROJECT_DIR`, and common unmodified hooks ref
### Containment
The config is parsed ONCE at load; a read/parse failure logs and registers nothing rather than crashing boot (a typo'd path must not take the agent down). Only `type: 'command'` hooks run — a `prompt`/`agent`/HTTP hook (CC) or an `async: true` / non-command hook (Codex) is parsed-and-skipped with a warning. The emit-listener paths (`session-start`, `subagent/start`) run detached, with their `inject` contained in a `.catch` that logs (a throwing inject must not break session boot or the loop).
The config is parsed ONCE at load; a read/parse failure logs and registers nothing rather than crashing boot (a typo'd path must not take the agent down). Only shell-form `type: 'command'` hooks run for CC; `http`, `mcp_tool`, `prompt`, and `agent` handlers are parsed-and-skipped. Codex runs only synchronous command handlers and skips `async: true` or non-command entries. The emit-listener paths (`session-start`, `subagent/start`) run detached, with their `inject` contained in a `.catch` that logs (a throwing inject must not break session boot or the loop).
### Where hooks run, and where their config comes from
Two different cwds, kept distinct on purpose. The hooks **themselves** run in the agent's **session workspace**: for the agent-scoped points the bridge threads the session's `cwd` (`session/new.cwd`, on the session header) to `runHook` as the process working directory, so a hook's `pwd` / relative-file read / marker write operates in the user's project tree, not the server's launch directory. The **config path**, by contrast, is **process-level**: `configPath` is resolved and parsed once at load against the process launch cwd, so a single `hooks.json` applies to the whole process — there is no per-session config discovery that reads a project-local `hooks.json` from each `session/new.cwd` (`TODO(per-session-hook-config)`). This is an honest limitation of the current cut: the example `cordis.yml` documents that its `./hooks.json` is process-level, not per-project.
Hooks run in the agent's session workspace, so relative paths target the user's project. `configPath` is resolved once against the process launch cwd and applies to every session. Per-session project-local discovery remains deferred under `TODO(per-session-hook-config)`.
## Deferred (faithful-but-degraded)
## Deferred compatibility gaps
- **Tool-input rewrite.** A CC/Codex `updatedInput` is logged + warned, not honored — input rewrite is a deferred consistency-design problem ([the pre-tool-input-rewrite RFC](../../proposed/feature/2026-06-30-pre-tool-input-rewrite.md)), because the pre-execution args are read by `tool/call` audit + `assistant/message` history + ACP/tool-bash presentation, so an honest rewrite is a design unit, not a field.
- **Stop loop-guard** (`TODO(stop-loop-guard)`). CC/Codex break an infinite force-continue with `stop_hook_active` (true once a Stop hook fired this run) plus a max-consecutive cap; both are deferred. Today `stop_hook_active` is always `false`, so a Stop hook that unconditionally blocks would force-continue every step — a hook author must self-limit until the guard lands.
- **Permission `ask`** degrades to `deny` at the `tools/pre-execute` seam (`FIXME(permissions)` in the interception-seams RFC) — there is no interactive permission prompt yet.
- **Stop loop-guard** (`TODO(stop-loop-guard)`). Claude Code supplies `stop_hook_active` and overrides a hook after eight consecutive blocks; Codex supplies `stop_hook_active` but documents no equivalent cap. Both bridges always report `false`, so a Stop hook that unconditionally blocks force-continues every step — a hook author must self-limit until state tracking lands.
- **Hook `continue:false` (hard halt).** A hook can ask to halt the whole run (CC/Codex `continue:false`); the shared merge folds it into `MergedHookOutcome.stop`/`stopReason`, but no bridge acts on it (`TODO(hook-continue-false)`) — the interception seams have no "hard-halt the agent" primitive yet (a Decision blocks/steers a single point, not the run). Deferred with the loop-guard work; the halt request is recorded in the `hook/result` log, and the hook keeps its per-point effect (decision/context) meanwhile.
- **Config discovery.** The path is explicit in `cordis.yml` and process-level (see above); the full multi-layer CC/Codex precedence walk, per-session project-local discovery, and the trust/hash model are not reimplemented (`TODO(per-session-hook-config)`).
- **Session-start / subagent-start context is best-effort, not gated (`TODO(session-start-gating)`).** `agent/session-start` is a synchronous emit and the bridge runs its hook on a detached `.then`, so the injected `additionalContext` is not guaranteed to land before the first turn reaches the model — a slow hook can miss the first request (the context then arrives as a later injection). `subagent/start` is sharper: an in-process provider may have already queued the child's prompt before the listener runs, and a short-lived child can finish before the detached inject fires. Making startup context a gated/awaited primitive is a loop-level change deferred to the interception seams; today the contract is "injected as soon as the hook resolves", not "before the first request". The bridge tests do NOT wait on the injection where they assert the guaranteed-timing behavior, so they document the real (best-effort) timing rather than masking it.
- **Session-start / subagent-start context is best-effort (`TODO(session-start-gating)`).** Both hooks run detached from startup, so their context is injected when ready but may miss the first request or a short-lived child. Guaranteeing first-request delivery requires an awaited startup seam.
## Alternatives considered
@@ -64,4 +65,4 @@ Two different cwds, kept distinct on purpose. The hooks **themselves** run in th
## Consequences
The bridges are thin and readable standalone: the correctness-critical halves (matcher semantics, exit-code contract, merge precedence) live in the shared `dsh-hook-protocol`, so each bridge is just config-parse + payload-build + outcome-map. Each is covered at per-file 100% — config-parse branches as unit tests, and the seam mappings end-to-end through the REAL loop + REAL `dsh-bash-local` + REAL shell scripts from a temp `hooks.json` (a scripted mock MODEL is the only stand-in), plus a real-Loader export-shape guard so a stray default export can't silently drop `inject`. Because the seams already carry typed Decisions, a future native plugin needs none of this bridge machinery — it returns a Decision directly.
Matcher semantics, exit-code handling, and merge precedence live in `dsh-hook-protocol`; each bridge only parses config, builds dialect payloads, and maps outcomes. Per-file coverage includes config branches plus end-to-end mappings through a real loop, `dsh-bash-local`, and shell scripts, while a real-Loader smoke guards the package export shape. Native plugins bypass the wire protocol and return typed decisions directly.

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@@ -23,8 +23,8 @@ A new `packages/hooks/` group with `hook-protocol` as a pure library. It owns fo
## Alternatives considered
**One parameterized engine.** A single engine parameterized by a full `dialect` descriptor was considered and rejected. The payload construction and decision mapping are where the dialects genuinely diverge (different field names, different supported outputs, CC's env/substitution); folding those into a data-driven descriptor would make the *bridge* logic indirect — a reader of `dsh-hooks-claude` would have to chase a descriptor to see what payload it sends. Keeping the truly-identical primitives shared (matcher, codec, runner, merge, events) and letting each bridge write its own straightforward payload+mapping keeps each bridge readable standalone, at the cost of a little duplication in the payload shape. The primitives are the part where duplication would actually be dangerous (a divergent matcher or exit-code rule is a correctness bug); the payload is the part where explicitness beats sharing.
**One parameterized engine.** Rejected because payload construction and decision mapping genuinely differ by dialect. Matchers, codecs, execution, merge rules, and events remain shared; each bridge keeps its payload and mapping explicit so its wire behavior is readable in place.
## Consequences
The two bridge plugins become thin: parse the config file, pick a matcher mode, build the per-event payload+env, call `runHook` + `mergeHookOutputs`, map the outcome to a Decision, and append `hook/*`. The protocol's correctness-critical halves (matcher semantics, exit-code contract, merge precedence) live in one tested place — `hook-protocol` ships with heavy unit tests (matcher per-mode, codec per exit-code/field, runner plumbing with a stub executor, merge precedence, the `hook/*` helpers) at per-file 100%. Input rewrite (`updatedInput`) is parsed but not honored (the deferred [pre-tool-input-rewrite RFC](../../proposed/feature/2026-06-30-pre-tool-input-rewrite.md)); a bridge logs+warns on it. The package is a library, so it has no `cordis.yml` load path of its own — its real-load-path coverage comes through the bridge plugins that consume it.
Each bridge parses config, builds its dialect payload, invokes the shared runner and merge logic, maps the decision, and appends `hook/*`. Protocol tests cover every matcher mode, exit-code and codec field, runner plumbing, merge precedence, and audit helper at per-file 100%; bridge tests exercise the library's real load path. `updatedInput` is parsed but only logged and warned until the [input-rewrite proposal](../../proposed/feature/2026-06-30-pre-tool-input-rewrite.md) lands.

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@@ -6,37 +6,47 @@ Status: implemented
The harness needs a hooks subsystem: users extend or gate the agent at lifecycle points the way Claude Code (CC) and Codex do. The key reframe driving this design is that **"native hooks" are not a package** — a native hook is just an ordinary Cordis plugin subscribing to the canonical lifecycle events. So the real product is a *powerful, well-typed canonical event surface*; the CC/Codex bridges (the `dsh-hooks-claude` / `dsh-hooks-codex` packages) are merely translators that map an external shell-hook protocol onto that same surface. Anything a bridge can do, a plain plugin can do directly — more powerfully (no serialization boundary, full `ctx`, typed returns).
Before this change the interception surface was incomplete and inconsistent for that goal: there was no per-prompt seam (CC's `UserPromptSubmit`), no session-start signal (CC's `SessionStart`), the single `tools/execute` waterfall conflated the pre-gate and post-inspect phases (CC splits `PreToolUse`/`PostToolUse`), and `agent/turn-continuation` returned a bare `boolean` with no room for a force-continue *reason*. The [event-domain-semantics RFC](../architecture/2026-06-30-event-domain-semantics.md) pinned down the three-domain rule and the typed-Decision idiom as the interception convention; this RFC builds the actual seams on top of it.
The surface needs distinct contracts for per-prompt policy (CC's `UserPromptSubmit`), session-start observation (CC's `SessionStart`), pre-tool policy, around-dispatch control, post-tool transformation, final-result observation, and continuation with a model-facing reason. Conflating those phases gives plugins mutation channels they do not need and makes finality depend on listener ordering. The [event-domain-semantics RFC](../architecture/2026-06-30-event-domain-semantics.md) supplies the three-domain rule and the typed-Decision idiom; this RFC applies them to the lifecycle seams.
## Decision
Add/reshape the interception seams so every one returns a small, seam-specific **typed Decision union**, and the set covers the hook points in scope (`session-start`, `prompt-submit`, `pre-tool`, `post-tool`, `stop`-via-continuation).
The canonical surface separates transformable policy, around-dispatch control, and observe-only notification. Policy waterfalls return small seam-specific **typed Decision unions**; wrappers return normalized results; notifications receive immutable snapshots and cannot affect the outcome. The set covers the hook points in scope (`session-start`, `prompt-submit`, `pre-tool`, `post-tool`, `stop`-via-continuation) while leaving non-hook execution policy independently composable.
**New `agent/*` events** (`dsh-agent`):
**Agent events** (`dsh-agent`):
- `agent/session-start(agent, source)` — emit, once before turn 1, carrying a `SessionStartSource` (`startup` for a fresh/forked create, `resume` for a reloaded persisted session; `clear`/`compact` reserved). A pure notification — it CANNOT block startup (a deliberate gap: a bridge logs/injects, it does not gate startup). A listener seeds context via `agent.inject()`.
- `agent/prompt-submit(agent, content, source, next) → PromptDecision` — waterfall, fired per drained queued message inside the open turn, before the `user/message` append. `allow` (optionally rewriting the prompt `content` or attaching `additionalContext`) or `block` (dropping the prompt; the loop appends a durable `prompt/blocked` in its place — see the dispatch note below).
- `agent/prompt-submit(agent, content, source, next) → PromptDecision` — waterfall, fired per drained queued message inside the open turn, before the `user/message` append. `allow` (optionally rewriting the prompt `content` or attaching separately sourced `additionalContexts[]`) or `block` (dropping the prompt; the loop appends a durable `prompt/blocked` in its place — see the dispatch note below).
**Reshaped** `agent/turn-continuation` from `(…, defaultDecision: boolean) → boolean` to `(…, defaultDecision: ContinuationDecision) → ContinuationDecision`. A `{action:'continue', reason?}` may carry model-facing context recorded as next-step steering in the same turn — the typed twin of the existing `/goal` step-end-steer pattern.
**`agent/turn-continuation`** receives and returns a `ContinuationDecision`. A `{action:'continue', reason?}` may carry model-facing content and source recorded as next-step steering in the same turn — the typed twin of the `/goal` step-end-steer pattern. It is not a `context/message`, so its type does not offer a context envelope or durable context metadata.
**Split** the single `tools/execute` waterfall into `tools/pre-execute` (→ `PreToolDecision` allow/deny/ask gate) and `tools/post-execute` (→ `PostToolDecision` accept/block, optionally replacing content or attaching `additionalContext`). Core dispatch sits between them as plain code inside `ToolRegistry.execute`'s outer try/catch, and the tool body keeps its own inner try/catch so a thrown tool still becomes an `isError` result that `post-execute` listeners can inspect.
### The tool pipeline gives each phase one kind of authority
**New `TurnEndReason` variant** `rejected` (`dsh-session`): a turn whose entire prompt batch was blocked by `prompt-submit`.
Every call follows `tools/pre-execute` → guards → `tools/execute` → dispatch → `tools/post-execute` `tools/result`. The registry snapshots caller input, materializes and freezes arguments, and assigns an opaque token. Nested calls carry only the parent token. Identity remains immutable; only `signal` may change around dispatch. The log, UI, and tool body therefore agree on what ran.
- **`tools/pre-execute`** is the extensible waterfall gate. Its `PreToolDecision` allows, denies, or asks. Deny skips `tools/execute` and core dispatch. Ask resolves through the optional approval seam: only `allowed-once` continues through guards and dispatch; rejection, cancellation, an unavailable channel, a missing approval service, or an agent-less call becomes a normalized denial. Every outcome still reaches post-policy and final observers.
- **`ctx.tools.guard()`** installs synchronous scope-aware policy after the whole pre-execute waterfall. A guard may deny or abstain, never force-allow, so listener ordering cannot resurrect an operation that a final invariant forbids.
- **`tools/execute`** is the around-dispatch waterfall for timeout, retry, and metrics plugins. A wrapper delegates to core dispatch with `next()`, may add, replace, or remove only `exec.signal` before doing so, and receives the already-normalized result of a thrown or unknown tool; returning its own valid result short-circuits dispatch.
- **`tools/post-execute`** is the inspect/transform waterfall. Its `PostToolDecision` accepts, blocks with feedback, optionally replaces content, or attaches `additionalContexts`. The returned decision is the supported transform channel; after the waterfall, the registry materializes the complete outcome once before final observation.
- **`tools/result`** is the synchronous contained notification after every transform, lossless-JSON materialization, and the outer error boundary. It receives the same frozen execution identity and an immutable snapshot of the authoritative result; observer failures are contained per listener and cannot change or reject `ToolRegistry.execute()`'s returned outcome.
Core dispatch and the tool body sit inside normalization boundaries, so tool, listener, malformed-result, non-JSON result, and identity-shape failures resolve as JSON-safe `isError` results rather than escaping the turn. A post-execute listener can therefore inspect a thrown tool, and a final observer sees exactly what the caller receives and the session log can persist.
**`TurnEndReason.rejected`** (`dsh-session`): a turn whose entire prompt batch was blocked by `prompt-submit`.
### Three load-bearing loop decisions
1. **Always open the turn first; a fully-blocked batch is a zero-step `rejected` turn; every veto is recorded as `prompt/blocked`.** `prompt-submit` fires AFTER `turn/start`, per message. A batch whose every prompt is blocked does NOT skip the turn — it opens a zero-step turn that closes with `rejected`. This one move resolves three problems at once: (1) turn-enclosure holds (every event has an open turn to live in); (2) the durable `turn/end` is appended and the ACP bridge settles normally off it (mapping `rejected``cancelled`) instead of hanging; (3) the block reason is a durable in-turn fact. Independently, each individual veto appends a `prompt/blocked` session event (the original `content`, `source`, and `reason`) in place of the `user/message` the prompt would have become — necessary because a MIXED batch (one prompt blocked, another allowed) does NOT end `rejected`, so the boundary reason alone would silently lose the blocked prompt on replay. An `allow`'s `additionalContext` is `inject()`ed into this now-open turn.
1. **Open the turn before prompt policy.** A fully blocked batch becomes a zero-step `rejected` turn, preserving enclosure and giving ACP a durable terminal event. Every veto also records `prompt/blocked` with the original prompt and reason, so mixed batches retain blocked inputs. Every allowed `additionalContexts` entry is injected into the open turn.
2. **Post-tool `additionalContext` is buffered and appended AFTER all `tool/result`s.** `content`/`feedback` shape the result `execute()` returns, but `additionalContext` is a SEPARATE `context/message`, and a single step can carry multiple tool calls. Appending context right after each result would interleave `result(c1) → context → result(c2)` and break tool-call/result adjacency. So `execute()` surfaces `additionalContext` on its `ToolExecutionResult`, and the loop buffers every per-call context for the step and appends them as `context/message`(s) only after every `tool/result` is appended.
2. **Post-tool `additionalContexts` are buffered and appended AFTER all `tool/result`s.** `content`/`feedback` shape the result `execute()` returns, but each context is a SEPARATE `context/message`, and a single step or composite tool can produce many. Appending context immediately would interleave `result(c1) → context → result(c2)` or place nested context before its outer result, breaking tool-call/result adjacency. `ToolRunContext.deferContext()` therefore collects nested-dispatch context through failures, `execute()` surfaces the ordered array on `ToolExecutionResult`, and the loop appends every entry only after every `tool/result` in the step. An accepted outer call preserves deferred contexts before decision contexts; an outer block discards deferred contexts and exposes only contexts explicitly supplied by the blocking decision.
3. **A forced `continue` `reason` is enqueued through the steering channel**, so the next step's top-of-loop drain records it as steering for the continued turn — next-*step* steering within the SAME turn, not a next-*turn* prompt (matching the existing `hasSteering` force-continue override).
### Pre-tool INPUT rewrite is DEFERRED (the over-reach signal)
### Pre-tool input rewrite is a separate consistency decision
`PreToolDecision` is allow/deny/ask only — **no `arguments` rewrite**. Output replacement (`PostToolDecision.accept.content`) is safe because `tool/result` is logged AFTER execution (one source of truth). Input rewrite is NOT safe today: `assistant/message` (the model-history source) and `tool/call` (the audit record) are both logged BEFORE execution, and live consumers READ `tool/call.arguments` for presentation (the ACP bridge remembers them for `presentResult`; `dsh-tool-bash` derives the title/cwd/terminal-vs-background from them). A rewrite that changed only execution would make the UI show one command while another RAN. Designing that consistently (rewriting the audit + history + presentation as one unit) is a real consistency-design problem CC itself warns is racy — so it gets its own [proposed RFC](../../proposed/feature/2026-06-30-pre-tool-input-rewrite.md), and `TODO(pre-tool-input-rewrite)` anchors it at the loop's pre-execute call site. This does not regress any production consumer (no production `tools/execute` listener mutated `exec.arguments`). The low-level capability to mutate `exec` in a `pre-execute` listener still exists (unadvertised — a test shim uses it to thread a generated id), but it is not a first-class advertised contract.
`PreToolDecision` cannot rewrite arguments. History and the audit call are logged before execution, and ACP presentation reads the same input, so the registry seals arguments before policy. A valid rewrite must update history, audit, presentation, and execution before identity is created; that contract belongs to the [input-rewrite proposal](../../proposed/feature/2026-06-30-pre-tool-input-rewrite.md).
### What this PR does NOT do
### Boundaries
It does **not** declare `hook/*` SessionEvents (the durable hook-invocation log) those belong to the `dsh-hook-protocol` library, because a native plugin can already use the typed Decisions without a durable hook log. A worked native-plugin example/test in this PR (`packages/core/agent-loop/tests/interception.spec.ts`) proves all the seams compose end-to-end through the REAL loop with NO `hook/*` involved — the concrete proof that "native hooks are just a plugin". Compaction (`PreCompact`/`PostCompact`), the Notification hook, Codex `PermissionRequest`, the permission/`ask` system, and the Stop loop-guard remain deferred (`FIXME(permissions)` marks the `ask`→deny degrade).
The seam package does **not** declare `hook/*` session events (the durable hook-invocation log); those belong to `dsh-hook-protocol`, because a native plugin uses typed decisions without an external hook log. The native-plugin integration test (`packages/core/agent-loop/tests/interception.spec.ts`) composes the seams through the real loop with no `hook/*` protocol. Compaction (`PreCompact`/`PostCompact`), Notification, and Codex `PermissionRequest` remain outside this decision. The [approval seam](2026-07-06-approval-seam.md) resolves `ask` decisions through `ctx.approval`, while terminal monotonic stopping is owned separately by `agent/turn-stop`.
## Alternatives considered
@@ -45,4 +55,4 @@ It does **not** declare `hook/*` SessionEvents (the durable hook-invocation log)
## Consequences
The canonical interception surface is now complete and uniformly typed: a native plugin returns typed decisions directly, and a CC/Codex bridge maps its protocol fields onto the same unions. The loop gained four firing points (session-start emit, prompt-submit waterfall, the post-tool context buffer, the continuation reshape) and the `dsh-tools` registry runs a two-waterfall pipeline; both are documented in [architecture.md](../../../architecture.md) and the package READMEs, and the decision types in [core-data-structures](../../../core-data-structures/core.md#interception-decisions) + [tools.md](../../../core-data-structures/tools.md). All existing `tools/execute` and `turn-continuation` listeners (tests, docs) migrated to the new seams. The ACP bridge maps the new `rejected` reason to `cancelled` (its codec). A pure internal change with no editor-visible transcript shift for the existing scenarios — the new behavior only fires when a hook is registered — so the snapshot goldens are unchanged; a hook-driven snapshot scenario lands with the `dsh-hooks-claude` bridge, which is what makes a hook observable end-to-end through ACP.
The canonical interception surface is uniformly typed without giving every extension the same power: hooks return decisions, execution wrappers wrap, terminal guards only deny, and final observers only observe. The loop owns session-start, prompt-submit, post-tool context buffering, and continuation; `dsh-tools` owns identity sealing and the five-phase execution pipeline. Their contracts are documented in [architecture.md](../../../architecture.md), package READMEs, [core interception decisions](../../../core-data-structures/core.md#interception-decisions), and [tool structures](../../../core-data-structures/tools.md). The ACP bridge maps `rejected` turns to its `cancelled` codec value, while hook-driven snapshots verify the observable bridge behavior end to end.

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@@ -24,7 +24,7 @@ class SessionStore extends Service {
`boundary` is the inclusive source event `seq` to copy through. When omitted, it defaults to the source session's current last event; on an empty source, omitted `boundary` creates an empty child. Fork-specific validation only checks that the requested boundary exists and is a `turn/end`. The selected prefix is then deep-cloned into the child seed. The child inherits the source session's `cwd`, stamps `parentSession` to the source id, and sets `seedLength` to the copied prefix length. When `childSessionId` is omitted, `SessionStore` generates one using its existing id policy.
The boundary rule is structural: an empty selected prefix is forkable, and any non-empty selected prefix must end at `turn/end`, regardless of the turn-end reason (`completed`, `aborted`, `error`, `disposed`, `max-tokens`, `interrupted`, or a future merge-extensible reason). A boundary that is not an existing event seq, is not a safe integer, or does not point at `turn/end` is rejected with a typed `SessionForkError` code. Broader session-log sanity remains in the existing invariant/repair layers: `dsh-invariants` checks turn enclosure and richer event ordering in dev, while persistence repair handles the valid crash-tail case of a final interrupted turn. The API also classifies non-live source ids (`SESSION_NOT_FOUND`), stale `Session` object references whose id is live on a different instance (`SESSION_NOT_LIVE`), duplicate requested child ids (`SESSION_ALREADY_EXISTS`), and invalid boundary values (`INVALID_BOUNDARY`).
An empty prefix is forkable; any non-empty boundary must be a safe existing sequence at `turn/end`, regardless of reason. Typed errors distinguish missing sources, stale objects, duplicate child ids, and invalid boundaries. Broader log validation and crash repair remain with their existing owners.
## Alternatives considered

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@@ -6,13 +6,13 @@ Status: implemented
The hooks subsystem ([interception seams RFC](2026-06-30-interception-seams.md)) lets a plugin observe and gate the agent at lifecycle points. Claude Code and Codex both expose **SubagentStart / SubagentStop** hooks, and CC's carry the subagent's final message. The harness already emits `subagent/start` and `subagent/end` lifecycle events ([the subagent capability-seam](2026-06-21-subagent-capability-seam.md)), but their payloads were minimal (`provider`, `id`, and on end `stopReason`) — not enough for a hooks bridge to report WHAT a subagent produced without separately reaching for the live run.
This RFC enriches the end payload. It is deliberately **observe-only**: no control-flow change, no waterfall, no `start()` restructure. A run-affecting subagent-stop decision (continuation, injection that changes the run) is a separate, larger redesign and stays out of scope.
This RFC enriches the end payload. It is deliberately **observe-only**: no control-flow change and no waterfall. A run-affecting subagent-stop decision (continuation, injection that changes the run) is a separate, larger redesign and stays out of scope.
## Decision
**Add `lastAssistantMessage` — the child's final output — to `SubagentRunEndInfo`.** On the settle path it is a DEEP CLONE of `SubagentResult.output` (so an observer sees WHAT the subagent produced without holding the run). On the REJECT path (an infrastructure fault where no `SubagentResult` was produced — the seam only knows `stopReason: 'error'`) it is absent. The clone is load-bearing for observe-only: the `subagent/end` emit fires from a detached `.then` registered *before* `start()` returns, i.e. before the caller's own `await run.result` continuation — handing listeners the same array reference would let a mutating listener corrupt the caller's `SubagentResult.output`. `structuredClone` makes the event a read-only view (a regression test mutates the event's array and asserts the caller's result is untouched); a clone failure is contained (logged, the event still fires without `lastAssistantMessage`) rather than becoming an unhandled rejection on the detached `.then`.
**Add `lastAssistantMessage` — the child's final output — to `SubagentRunEndInfo`.** On the settle path it is the readonly typed `SubagentResult.output`, so an observer sees what the child produced without holding the run. On an infrastructure rejection where no `SubagentResult` exists, it is absent and the event reports `stopReason: 'error'`. Providers and listeners are trusted same-process collaborators and honor the borrowed immutable payload contract.
Both events stay plain **`emit`s**. `subagent/end` fires from a detached `.then` on `run.result` and awaits no listener, so it is genuinely observe-only by construction — a `subagent/start` listener can still reach the live child via `ctx.agents.get(info.id)` and `inject()` into it; a `subagent/end` listener can only observe (the run has settled). Per-listener containment (already in place) keeps one bad subscriber from stranding a live run or surfacing as an unhandled rejection on the detached settle hook.
Both events stay plain **`emit`s**. Async `SubagentService.start()` attaches result observation to the ready provider run, emits `subagent/start`, and then returns the run; an in-process listener can therefore reach the published child via `ctx.agents.get(info.id)`, while a remote provider need not have a local registry entry. A rejected provider start emits neither event. The callbacks remain observe-only and per-listener containment keeps one bad subscriber from stranding a live run or starving later listeners.
## Alternatives considered

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@@ -0,0 +1,78 @@
# RFC: Dynamic workflows — a script-driven multi-agent orchestration seam
Status: implemented
## Problem
The harness can delegate ONE task to ONE child (`dsh-tool-subagent`), but work that fans out across many independent pieces — an audit over many files, a migration, multi-angle research, adversarial verification of findings — forces the model to orchestrate turn by turn: every intermediate result lands in the parent context, the plan lives nowhere durable, and coordination costs a model round-trip per step. Claude Code ships this capability as [dynamic workflows](https://code.claude.com/docs/en/workflows): the model writes a JavaScript orchestration script, a runtime executes it, and the script — not the conversation — holds the loop, the branching, and the intermediate results.
## Decision
A workflow capability family at `packages/workflow/` in the bash seam shape (interface / implementation / consumer), plus the structured-output foundation it needs on the subagent seam.
### The script contract (Claude Code-compatible)
A workflow call contains JSON `meta` (`name`, `description`, and optional `whenToUse`/`phases`) and a JavaScript `script` body with top-level `await` that returns a JSON value. Metadata is validated as data and never evaluated. The body receives `agent(prompt, options)`, `parallel(thunks)`, `pipeline(items, ...stages)`, `phase(title)`, `log(message)`, and `args`. Pipeline stages receive `(prev, item, index)` with no cross-stage barrier; failed children and ordinary stage errors resolve the affected item to `null` and skip its remaining stages. Claude Code's determinism restrictions are deferred with journaling, so compatible bodies may use clock and randomness after moving their meta header into the parameter.
One deliberate strictness DIVERGENCE from CC: hook misuse — unknown or deferred options (`effort`/`isolation`/`agentType`), malformed arguments, schemas outside the supported subset, tripped caps, seam start failures — throws a `WorkflowError` with `fatal: true`, and the combinators RE-THROW fatal errors instead of nulling the item. Without this, a typo'd option dissolves into a `null` indistinguishable from a child failure — the accepted-then-ignored failure mode this repo bans. One addition: the tool's `args` parameter is a JSON OBJECT (a bare list is wrapped as a field) so the wire schema stays honest.
### The seam (dsh-workflow)
`ctx.workflows` is an abstract `WorkflowService` in the bash shape — one engine per context, no named-provider registry (engines are deployment swaps, not co-residents). `start(request)` throws synchronously for a script that cannot begin; a returned `WorkflowRun`'s `result` NEVER rejects (failures resolve as `stopReason: 'error' | 'cancelled'`). The `workflow/*` events are observe-only emits carrying DATA SNAPSHOTS (id + meta; `workflow/end` omits the result value), per-listener contained, mirroring `subagent/start`/`subagent/end` — control stays with the run's holder. Vocabulary details: [core-data-structures/workflow.md](../../../core-data-structures/workflow.md).
### The engine (dsh-workflow-workerthread): one worker thread per run
**Trust premise**: workflow scripts have the same trust as the model's bash access. The engine contains buggy scripts and guarantees settled results, JSON-safe values, and cancellation quiescence; it does not defend against hostile code. A vm context and worker thread are not security boundaries: a script can escape to Node APIs with process-wide authority. Sandboxing requires a separate-process or isolated-vm engine behind this seam.
**Why `node:worker_threads`**: each run gets one unpooled worker. A vm context limits the documented script surface, while message-port RPC bridges `agent()` to host-side child loops. The worker prevents synchronous script work from blocking the host, provides a serialization boundary, and permits forced termination after cancellation. `isolated-vm` was rejected because of its maintenance state and deployment requirements.
The host validates metadata and parses the body before publication. Private enum-keyed payload maps define the wire protocol; pending starts, published child records, one cancellation signal, worker-death reaping, result precedence, and disposal quiescence preserve the subagent run contract across it. The [agent-scope runtime-design RFC](../architecture/2026-07-12-agent-scope-runtime-design.md#workflow-children-are-pending-starts-or-published-records) owns those race algorithms.
The engine exposes an in-process `MessageChannel` test path because main-process V8 coverage cannot see worker execution.
**Meta is data**: the schema-validated `meta` field reaches the seam as JSON and is only shape-validated. The host never evaluates a metadata literal, which would let script-controlled accessors run outside the worker's isolation.
**Value boundary**: `materializeFromRealm` copies outbound values and rejects functions, symbols, nested `undefined`, exotic prototypes, cycles, sparse arrays, and non-finite numbers. Data-property copies make `"__proto__"` safe; getters are read normally and a throwing getter fails loudly. `args` crosses through `workerData` and is cloned again before exposure. Realm functions are invoked rather than copied, and thrown values use a total renderer so `result` cannot reject. Hook errors are host-realm `WorkflowError`s, so scripts branch on `name` or `code` rather than `instanceof Error`, as documented in the engine README. Concurrency, total-agent, item, timeout, and grace limits are validated config.
### The consumer (dsh-tool-workflow)
A `workflow` tool mirroring `dsh-tool-subagent`'s synchronous shape: start, await, `try/finally` dispose, abort-bridge `exec.signal`, non-`completed``isError`. Render intent: a `generic` card titled by the call's `meta.name` parameter (presentation is a pure function of args). The tool description IS the model-facing authoring spec. The usage policy ships with the tool as its own `tool:<toolName>` prompt section (explicit-ask-only guidance — tool guidance lives in tool plugins, never in the deployment persona); the harness has no ultracode-style effort gate.
### The foundation: structured output on the subagent seam
`SubagentStartRequest.outputSchema` is implemented by `dsh-subagent-inprocess` for both in-process backends. Each structured child receives its own scoped capture tool, instruction, and enforcement registrations on `child.ctx`; concurrent children can use different schemas without sharing mutable policy, and disposing the child removes the entire attachment.
An output schema makes a schema-valid committed capture mandatory for successful child completion. The scoped runtime presents the capture tool and instruction, commits only a successful final outcome—including the enclosing `run_code` outcome for an SDK call—denies later side effects after capture becomes pending, and stops the child without another model step after commit. A validation failure remains a retryable tool error; clean completion without a committed capture settles as an error.
`StructuredOutputSchema` is the raw enforceable JSON-Schema subset in `dsh-tools` (single-string `type`, `properties`/`required`/`additionalProperties`, `items`, scalar `enum`/`const`), and unsupported keywords fail loudly because that wire data becomes the capture tool's parameters verbatim. The [agent-scope runtime-design RFC](../architecture/2026-07-12-agent-scope-runtime-design.md#structured-output-commits-only-authoritative-outcomes) owns the assembly, commit, guard, and terminal-stop correctness algorithms.
## Testing
Worker-side logic runs through an in-process `MessageChannel` so V8 coverage measures it. Unit tests cover script helpers, fatal and nullable failures, JSON boundaries, caps, cancellation, child ownership, and structured output through real loops. A built-bin smoke runs the separately bundled `lib/worker.cjs` under plain Node, a with-key e2e drives real child agents, and model-facing workflow behavior is snapshot-covered through its owning example.
## Deferred (documented non-goals of this cut)
- **Background collection** (start tool → run id → completion notice → collect), designed alongside bash/subagent background unification.
- **Journaling + resume** (`resumeFromRunId`, cached agent() prefixes) — implementing it reintroduces CC's determinism bans as a script-contract tightening (scripts may read the clock today).
- **Saved/bundled workflows** (a `.deepseek/workflows/` registry, slash-command surface) and **script persistence to a run directory** (the tool-call event already records the script durably).
- **Nested `workflow()`**, **token `budget`**, and the `effort`/`isolation`/`agentType` agent options (each rejects loud with a message naming it deferred).
- **An overall run wall-clock timeout** — cancellation always frees the caller (result settles within the grace), so a cap on total run time is a policy knob for the background redesign, not a correctness need here.
- **Engine hardening beyond worker threads**: an isolated-vm or separate-process engine behind the same seam (actual sandboxing; memory limits).
- **ACP progress UI** over the `workflow/*` events (a `/workflows`-style view); the events exist for it.
- **ACP-backend structured output** and **`toolFilter`** (both still capability-gated `false`).
## Alternatives considered
- **Hostile-value containment in the host** (trap-free proxy rejection, accessor-never-invoked descriptor walks, realm-side pre-rendering of thrown values, realm-built promises/arrays/error clones with structural fatal recognition): rejected because every defense targets an author the trust premise accepts, while the thread's serialization boundary already makes cross-realm values total by construction.
- **In-process `node:vm` execution**: mechanically simplest — no RPC, no thread — but `start()` blocks the caller for the script's initial synchronous slice, a synchronous spin past the first await cannot be killed in-process (the vm `timeout` covers only that first slice), and `dispose()` could only abandon an unsettling script on the host loop. The worker-thread engine keeps the same vm-context script surface while unblocking the host and making termination real.
- **Background execution as the default** (CC's shape): deferred; foreground-synchronous matches `dsh-tool-subagent`'s cut, and background semantics should be designed ONCE across bash/subagent/workflow rather than per-tool.
- **Workflow-layer JSON parsing for `agent({schema})`**: duplicating a seam concern at one consumer while the seam's capability flag stayed dishonestly `false`.
- **Meta embedded in the script as `export const meta = {...}`** (CC's exact format): keeps scripts self-contained and CC scripts drop-in, but obtaining meta requires evaluating model-written text on the host. Even an empty timed vm context cannot bound script-controlled getters when the host reads the resulting object. A JSON parameter removes the scanner, evaluation, and host-spin hole; the cost is that a CC script's meta header must move into the parameter (the body stays drop-in).
- **`SchemaSpec` as the outputSchema type**: the author-facing DSL cannot express what arrives as data and cannot be validated against without conversion loss.
- **A schema-object library (zod, or the repo's schemastery) for the structured-output subset**: the schema is wire data — plain JSON that crosses the vm realm boundary in `agent({schema})` and lands verbatim in the forced tool's parameters — exactly where live schema objects cannot sit; consuming raw JSON Schema at runtime would need a third-party converter on top (zod core only emits JSON Schema, not the reverse), and it would put a second schema language beside schemastery's config role.
- **ajv for value validation**: it validates FULL JSON Schema, so the subset gate — the module's actual point, since every accepted keyword must be one the harness enforces — would remain hand-written regardless; it compiles validators through `new Function`; and it would be dsh-tools' first runtime dependency, all to replace the ~70-line value walker while the path-qualified, every-violation error reporting stays custom either way.
- **Provider JSON mode instead of the capture tool:** it guarantees valid JSON, not schema conformance, and its interaction with tool calling is unclear. The capture tool preserves in-turn validation retries. Provider-side strict tool schemas can later narrow the accepted subset without changing this design.
## Consequences
Fan-out plans now live in rerunnable scripts, and `outputSchema` provides authoritative structured child results. Each run pays worker startup and message-port RPC costs, but host startup stays non-blocking, cancellation can terminate the worker, and serialization enforces the value boundary. Worker threads are not a security boundary. Invalid options fail rather than degrading to Claude Code's `null`; consumers retain control through the run handle while observers receive snapshots only.

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# RFC: Skill system — progressive disclosure instructions for agents
Status: implemented
## Problem
Agent products have converged on a skill pattern: keep the request prompt small by listing only available instruction bundles, then load the full body when the model decides a task matches. Codex, Claude Code, OpenCode, and Kimi Code differ in details, but all separate discovery metadata from complete instructions so a workspace can carry reusable behavior without paying the full prompt cost on every turn.
DeepSeek Harness uses the same primitive so project-specific review, plugin-authoring, and tool-usage guidance lives next to the workspace or the user's agent configuration instead of being hard-coded into the loop.
## Decision
`@deepseek-ai/dsh-skill` is the pure provider registry (`ctx.skills`), `@deepseek-ai/dsh-skill-local` is the shipped local filesystem provider, and `@deepseek-ai/dsh-tool-skill` owns the session-prefix catalog and model-facing loader tool. `dsh-agent-spine-demo` loads the registry, local provider, and consumer by default so stdio and ACP apps get the same behavior while embedded or remote providers contribute skills without changing the registry or consumer. Its `skills` config forwards `registry`, `local`, and `tool` branches to those owners.
Provider plugins register synchronously during `apply()`. Provider membership is direct effect-owned state: registration and disposal invalidate completed catalogs synchronously, and discovery reads the current provider map on demand rather than observing registry-change events. Provider catalogs return ranked candidates from awaited `list()` calls, where remote providers perform initialization, authentication, and discovery while honoring the lookup abort signal. The registry validates each candidate, resolves same-name skills first-wins by rank, provider registration order, and provider-local order, then sorts summaries by skill name for deterministic consumers. It caches only completed catalog snapshots and retries when a provider/runtime revision changes during discovery, so an unload cannot freeze a stale, unresolvable skill into a session prefix. Runtime `ctx.skills.register(...)` remains a convenience for embedded in-process skills and uses project-over-user priority; `runtime` is reserved as the registry-owned provider name.
The local provider scans cwd-sensitive project roots, custom roots, and user roots in first-wins rank order: project `.dsh`, project `.agents`, `customSkillDirs`, user `.dsh`, then user `.agents`. The user `.dsh/skills` scan skips `.system` so a system-owned directory is not treated as normal user content. DeepSeek Harness does not ship built-in system skills; embedded or remote providers supply additional skills when configured.
Each skill is either `<name>/SKILL.md` or `<name>.md` with YAML frontmatter. `name` and `description` are required; `whenToUse`, `disableModelInvocation`, and `metadata` are optional. Names are kebab-case. YAML frontmatter is parsed with the `yaml` package instead of `js-yaml` or a hand-written parser: `yaml` is the already-declared modern parser for this package's limited frontmatter needs, and a narrow parser would either reject valid YAML users expect to work or grow into an unreviewed YAML subset.
Local skill filesystem I/O goes through `ctx.fs` when a filesystem service is loaded: project-root lookup probes `.git` with `resolve` and `stat`, root discovery uses `listDir`, and skill reads use `readText`. The Node filesystem remains a fallback for minimal contexts that mount `dsh-skill-local` without the fs seam. Missing roots, unreadable or malformed skill files, and transient provider `list()` failures degrade to warn-and-skip so one bad source does not make every agent request fail; malformed candidates still fail fast because they are provider contract violations.
`dsh-tool-skill` contributes one user-role `<system-reminder>` catalog through [`agent/session-prefix`](2026-07-07-session-prefix.md). The catalog contains sorted skill name and description only; it excludes bodies, paths, sources, providers, and routing hints. Descriptions are whitespace-normalized, XML-escaped, and capped by `catalogDescriptionMaxLength`, whose default is `500` and minimum is `3`. The session-prefix seam freezes the request-only catalog per loop instance and records it in the request header, preserving reconstructability without adding it to durable history. Full skill bodies are never included in the catalog.
The `skill({ name })` tool loads one full skill for the current agent cwd and returns a tool result containing `<skill_content name="...">`, `<skill_resources>`, and `<skill_instructions>`. `resourceBase` supplies a directory, URL, or opaque provider-managed base for explicitly referenced scripts, references, and assets; resources load only as needed, without directory enumeration. An unresolved name reports that the skill is unknown or no longer available; invalid names and skills marked `disableModelInvocation` retain distinct tool errors. The tool result is the model-visible disclosure path.
The data structures and catalog/tool contract are documented in [skills.md](../../../core-data-structures/skills.md), with service signatures in the generated [services catalog](../../../cordis-catalog/services.md).
## Alternatives considered
**Inject full skill bodies into every system prompt.** Rejected because it destroys progressive disclosure and makes every request pay for instructions that may not apply.
**Expose skills only as slash commands.** Rejected because model-initiated loading is the core capability; slash/ACP command advertisement does not change discovery.
**Put local filesystem scanning directly inside `ctx.skills`.** Rejected because coding agents, web agents, and future plugin ecosystems need different skill sources. A provider registry mirrors the subagent seam: the registry owns conflict resolution and consumers, while implementations own loading.
**Use a system-prompt section.** Rejected because the rendered system prompt is a single string, while the catalog is a user-role `<system-reminder>` message with request-only lifecycle requirements. [`agent/session-prefix`](2026-07-07-session-prefix.md) is the selected mechanism: it places the catalog ahead of derived history and records the composed message in the request header.
**Materialize built-in DSH authoring skills under `~/.dsh/skills/.system`.** Rejected because bundled skills do not write user home on startup, and embedded or remote providers supply configured skills.
**Recursively discover nested `**/SKILL.md`.** Rejected. Flat files and one-level directory bundles cover the configured roots while keeping duplicate handling and catalog order easy to reason about.
**Hand-parse frontmatter.** Rejected because the accepted schema includes an open `metadata` object. A narrow parser would either reject valid YAML users expect to work or grow into an unreviewed YAML subset.
## Consequences
The agent-core spine includes one session-prefix contributor, one local provider, and one model-facing tool. Skill discovery is cwd-sensitive, so callers that create agents with different session cwd values can observe different project skill overrides by design.
The catalog is deterministic for a fixed root set and runtime registration revision, but disk changes are not watched; discovery is memoized until runtime registration invalidates the cache or the process restarts.
## Deferred
Forked skill contexts (`context: fork`), direct user/slash invocation (`user-invocable`), parameter declarations and hints (`arguments` and `argument-hint`), and per-skill tool constraints (`allowed-tools` and `disallowed-tools`) are outside the shipped contract. The registry, local provider, and model-facing tool do not parse, advertise, or enforce these fields.

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# RFC: The approval seam — one-shot permission decisions over a waterfall of answerers
Status: implemented
## Problem
Two callers need to put one question — "may this specific action proceed?" — to a human: `tools/pre-execute`'s `ask` decision (including the Claude-Code hook bridge's `permissionDecision: ask`) and the [sandbox RFC](2026-07-06-sandbox.md)'s post-denial one-shot escalation retry. A shared seam keeps them from inventing separate outcome vocabularies, UI routing, cancellation, and audit trails, while guaranteeing that a deployment with no UI can never grant an unanswerable request.
The routing problem is ownership: an approval prompt must reach the editor session that owns the asking agent (the ACP bridge multiplexes N sessions over one connection), fail closed for agents nobody owns (in-process subagents, tests), and stay out of deployments that compose no UI (headless, CI).
## Decision
One package, `dsh-user-approval` (`packages/ui/user-approval`), owning the vocabulary and the `ctx.approval` service — the MECHANISM. The POLICY — who answers, and whether a session is asked at all — lives outside it: answerers are `approval/request` waterfall listeners registered by the plugins that own the channel (the ACP bridge; future terminal UIs; test scripts), and a per-session policy tier can decide before any human is involved. Consumers (`dsh-tools`' ask routing, the sandbox escalation gate) resolve a question to a closed outcome and derive their own tool results from it. Deliberately ONE package, not the capability-seam three (see Alternatives).
### How a deployment uses it
One `cordis.yml` entry mounts the seam. Not loading it is the fail-closed opt-out: consumers deny unanswerable requests with zero approval code registered.
```yaml
- id: approval
name: '@deepseek-ai/dsh-user-approval'
# config:
# policy: never # deployment default for sessions without an override; 'ask' when omitted
```
The entry alone provides mechanism, not a channel: with no answerer composed, every ask resolves `unavailable` and the asking tool call denies — fail-closed needs no configuration. Composing the ACP app (`@deepseek-ai/dsh-acp-demo`, as in [the acp-agent example's default tree](../../../../examples/acp-agent/README.md)) completes the loop: its bridge registers an answerer that prompts the owning editor session via `session/request_permission`, so a hook's `ask` or an escalation request surfaces as a one-shot Allow/Reject prompt attached to the already-streamed tool call. `policy: never` is the unattended stance — every ask auto-rejects deterministically, stated in the system prompt, no human in the loop. `policy` is validated against the closed list at plugin load; anything else throws.
What a composed deployment observes: `allowed-once` lets exactly that call proceed; rejection, dismissal, and channel absence deny with three distinct reasons the model can tell apart; every ask lands a durable `approval/asked`/`approval/decided` pair on the asking agent's session log; nothing about a grant persists past the call that asked.
One ask under this composition, verbatim from the sandbox example's recorded `escalation-approved` scenario — the model requests a sandbox escalation, the gate asks, the bridge prompts the owning editor, the user clicks Allow once:
```
tool/call bash {"command": "printf 'escalated\n' > escalated.txt && cat escalated.txt",
"sandbox_permissions": "workspace-write",
"justification": "the user asked to write escalated.txt in the workspace"}
approval/asked {"toolName": "bash", "callId": "call_00_…",
"reason": "escalate sandbox to workspace-write: the user asked to write escalated.txt in the workspace"}
→ session/request_permission {"toolCall": {"toolCallId": "call_00_…"},
"options": [{"optionId": "allow-once", "name": "Allow once", "kind": "allow_once"},
{"optionId": "reject-once", "name": "Reject", "kind": "reject_once"}]}
← the user picks "Allow once" on the prompt the editor attaches to the streamed bash call
approval/decided {"outcome": "allowed-once"}
tool/result "escalated" — this one call ran under the wider mode; the grant died with it
```
The `escalation-rejected` twin ends in `{"outcome": "rejected"}` instead: nothing executes, and the model's result carries the asker's verbatim fail-closed text (`the user rejected escalating this command to "workspace-write"`). A hook's `permissionDecision: ask` rides the identical wire; only the asker and its deny texts differ (§ Ask routing in dsh-tools). Headless, the same request skips the prompt entirely and settles `unavailable`.
### Design detail
#### The seam: mechanism and policy split
After validation and an `approval/asked` append, `request()` resolves to `allowed-once`, `rejected`, `cancelled`, or `unavailable`. The service borrows the readonly request, runs the answerer waterfall, races cancellation, and normalizes thrown or invalid answers to `unavailable`. It then appends the matching `approval/decided`, paired by `ApprovalRequestId`.
Both audit events must be inside an open turn; acceptance or a pre-commit append failure rejects the request. Post-commit observers are contained by the session. `allowed-once` grants only the requested action, and the service retains no grant state.
Answerers are `approval/request` waterfall listeners. A listener returns an outcome for an agent it owns and calls `next()` otherwise. With no answerer, the default is `unavailable`; unloading a UI therefore fails closed without leaving a channel. Because sibling registration order is not deterministic, a deployment composes one terminal answerer and uses `prepend` only for decide-or-delegate gates.
`ApprovalRequest` carries the agent, tool name, optional `callId`, reason, and signal. The agent routes both the prompt and audit events. The request uses `dsh-llm`'s `CallId` without importing `dsh-tools`, avoiding a package cycle. Tool arguments are omitted because UI answerers attach to the already-rendered call.
#### Ask routing in dsh-tools
`ToolRegistry.execute()` sends `ask` through the approval seam before the deny path. Only `allowed-once` proceeds; rejection, cancellation, and an unavailable channel produce distinct model-visible reasons. The registry looks up the optional service per call, so an absent or unloaded service fails closed without gating the registry fiber. Agent-less execution also fails closed because it cannot be routed or audited.
#### The per-session policy tier
The seam owns the session policy `'ask' | 'never'`, following the switching contract in the [sandbox RFC](2026-07-06-sandbox.md). The effective session or config policy is applied before answerers: `'never'` rejects inside `request()`, while `'ask'` dispatches and falls through to `unavailable` when unanswered. The prompt states only deterministic `'never'`; the narrator reports switches, and every request still receives its audit pair.
#### The ACP answerer
The ACP bridge finds the owning session, sends `session/request_permission` for the `callId`, and maps one-shot allow, reject, and cancel responses to the seam vocabulary. Unknown selections never grant. Foreign agents and requests without a `callId` delegate via `next()`; RPC failure becomes `unavailable`. The bridge answers requests but does not decide which calls require approval.
The answerer routes through the bridge's reverse-map ownership seam described by [the ACP support RFC](../../implemented/feature/2026-06-14-acp-agent-client-protocol.md), implementing the per-session permission ownership required by [the multi-session RFC](../../implemented/feature/2026-06-14-acp-multi-session.md).
#### Audit, and what the model sees
`approval/asked` and `approval/decided` are durable log-only events. The model sees only the asker's logged `tool/result`. Every accepted request appends one matching decision, including cancellation and contained answerer failures.
#### Entities and dependencies
`dsh-user-approval` owns the fixed dispatch-and-audit mechanism; `dsh-tools` asks and `dsh-acp` answers. Replaceable answerers remain listeners in their channel-owning plugins, so a three-package capability split would add an empty implementation layer. Sandbox executors remain transport-only, and static capability grants remain separate from interactive approval.
### Testing
- **Unit/integration:** cover first-wins delegation, fail-closed defaults, malformed and throwing answerers, cancellation races and late-answer discard, audit pairing despite observer failures, unbypassable `'never'`, distinct tool-denial reasons, and ACP per-session routing/outcome mapping.
- **Snapshot:** script permission answers through both sandbox escalation branches and pin the `'never'` prompt plus policy-switch notice. Hook-produced asks without a composed answerer remain covered as fail-closed denial.
## Deferred
- **`allow_always` grant storage** — honoring a persistent grant means designing storage, scope identity (call? path? prefix? session? time window?), and revocation; until designed, only the one-shot options are advertised ([the sandbox RFC](2026-07-06-sandbox.md) § Escalation records the open scope question).
- **A recorded hook-produced ask with a composed answerer** — escalation records the human-prompt wire, while the current hook fixture pins the no-service denial; their combined producer/answerer path remains unit-covered.
- **Routing a child agent's approvals to the parent session** — `subagent-acp`'s child auto-answers its own `permission` requests; surfacing them to the parent's editor is its own design.
## Alternatives considered
- **A single registered provider instead of waterfall listeners** — rejected: a `registerProvider()` surface forces every composition question — allowlist pre-filters, external hook deciders, scripted test answers, a policy gate in front of a human — inside one provider implementation. The waterfall gets composition, fail-closed absence, and HMR disposal from machinery the runtime already has; the seam's JSDoc pins the single-decision-slot convention instead of inventing a provider registry.
- **An inline `tools/pre-execute` permission gate in the ACP bridge** — rejected: prompting for every bridge-owned call hardwires the asking POLICY into the UI plugin, cannot serve a second asker (sandbox escalation happens after execution starts, with no pre-execute moment), and leaves hook-produced `ask` decisions without a shared mechanism.
- **The generic user-interaction seam (`ctx.userInteraction`)** — rejected as the approval mechanism: the two share a skeleton (route by agent, block for a human, handle absence), but approval's contract is narrower in every dimension that matters: a closed outcome vocabulary instead of free text, a protocol-native prompt attached to a tool call instead of a generic form, mandatory fail-closed absence, and audit events. Approval therefore does not ride the shipped `packages/ui/user-interaction` / `ask_user_question` elicitation path — an elicitation form is not a permission prompt, and a free-text answer is not a closed outcome; sharing provider plumbing stays open if the two ever converge.
- **Static optional injection in `dsh-tools`** — rejected: the vendored cordis `Inject` type has no optional flag — the object form maps service names to intercept config, and a declared inject gates the fiber. `ctx.get('approval')` is the documented opportunistic-consumption pattern (the `tool-bash` owner-token lookup, the loop's persistence probe), reads presence per call, and degrades correctly across HMR without extra machinery.
- **The capability-seam three-package split** — rejected: interface/implementation/consumer fits a seam whose implementation is swappable (bash-local vs bash-sandbox). Here the service body is fixed mechanism and the variable part is listeners that live with their owners — splitting would manufacture an implementation package with nothing in it ("don't split preemptively").
- **Offering `allow_always` now** — rejected: the protocol can express it, but honoring it means designing grant storage, scope identity, and revocation (§ Deferred). Advertising an option the harness cannot honor manufactures doomed grants.
## Consequences
- Only `allowed-once` dispatches an asked-about action; absent, rejected, cancelled, or failed answer paths deny.
- Session ownership routes prompts, policy, and audit events without crossing editor sessions.
- Accepted requests append one durable audit pair; the model sees only the resulting tool result.
- A deployment without the service emits no approval prompt or audit events and denies every `ask` at the tool boundary.
Costs and accepted limits:
- **Two decide-eager answerers race for the slot.** Sibling-plugin listener order is not deterministic, so the seam cannot referee competing terminal answerers — mitigated by convention (one terminal answerer per deployment; `prepend` only for decide-or-delegate gates) rather than a priority mechanism the event bus does not have.
- **Production exercise rests on one composition.** `ask` has two producer families — the hook bridges through `tools/pre-execute`, and sandbox escalation through its own gate — with the wire recorded in the sandbox example's snapshot suite, so the seam's real-world coverage is that one composition until more deployments compose it.
- **Ownership keys on `Agent` object identity.** The answerer resolves sessions through the bridge's existing WeakMap; every current path hands the same object through the loop and the seams, but a future boundary that clones or proxies agents would make the bridge delegate and fail closed — safe, but silently UI-less — and would need session-id matching instead.
## FAQ
- **What happens in a deployment with no answerer at all (headless, CI)?** Every ask falls through the empty waterfall to `unavailable` and the tool call denies with the "no approval channel is available" reason. Fail-closed is the zero-listener default, not a configuration.
- **Can a grant persist — "always allow this"?** No. `allowed-once` authorizes the single asked-about action and the service stores nothing between requests; `allow_always` is deliberately not advertised until grant storage is designed (§ Deferred).
- **What does the model see of an approval?** Only the tool result the asker derives from the outcome — the audit pair never enters the transcript. The three non-grant reasons are distinct, so the model can tell a human "no" from a dismissed prompt from a missing channel.
- **Who decides whether a call asks in the first place?** Policy producers: a hook returning `permissionDecision: ask`, any `tools/pre-execute` listener, or the sandbox escalation gate. The seam and the bridge only route and answer; neither injects its own judgment about what deserves a prompt.
- **What happens when the user dismisses the prompt, or the turn aborts mid-ask?** Dismissal maps to `cancelled` with its own deny text. An already-aborted signal settles `cancelled` without dispatching; an abort during the ask discards the late answer — one audit pair either way, never two.
- **What if the client answers with an option the harness never offered?** Any selection other than the offered `allow_once` maps to `rejected` — an unknown optionId from a non-conforming client can never grant.
- **How do subagents' approvals route?** An agent no answerer owns delegates through the whole waterfall and fails closed — in-process subagents are deliberately unanswerable. `subagent-acp`'s child-side auto-answer is separate; routing a child's asks to the parent's editor is deferred (§ Deferred).
- **What does `policy: 'never'` actually change at runtime?** The service resolves every ask for that session to `rejected` before dispatching any answerer (in-service, so no registration order can bypass it); the system prompt states the policy; switches are narrated at boundaries; the audit pair still lands for every auto-rejection.
- **What happens across a hot reload, or when the UI plugin unloads mid-session?** Answerers dispose with their owning fiber, so the next ask degrades to `unavailable` instead of hanging on a dead channel; remounting re-registers the answerer with no catch-up state.
- **Where does the user see what they are approving?** On the tool call itself: the prompt attaches to the already-streamed call via `callId` — arguments included — and adds the asker's human-readable `reason`; the request carries no argument copy of its own.
## Prior art
In-repo precedents this design copies or contrasts with:
- The `fs/write-intent` gate (`packages/fs/fs/`) — the documented single-occupancy decision-slot waterfall semantics (first answer wins, delegate via `next()`) the answerer contract reuses.
- `hook/invoked`/`hook/result` — the log-only audit-pair precedent `approval/asked`/`approval/decided` follows; [the hook-bridges RFC](2026-06-30-hook-bridges.md) ships `permissionDecision: ask`, the first producer.
- [The interception-seams RFC](2026-06-30-interception-seams.md) — the `tools/pre-execute` `allow`/`deny`/`ask` vocabulary whose `ask` this seam services.
- [The ACP support RFC](../../implemented/feature/2026-06-14-acp-agent-client-protocol.md) — the `WeakMap<Agent, sessionId>` ownership seam the answerer routes through; [the multi-session RFC](../../implemented/feature/2026-06-14-acp-multi-session.md) — the per-session permission-ownership blocker this implements.
- The opportunistic `ctx.get()` consumption pattern (`tool-bash`'s owner-token lookup, the loop's persistence probe) — how `dsh-tools` consumes the seam without gating its fiber on it.

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# RFC: Explicit model-facing tool order
Status: implemented
## Problem
Model-facing tool order followed plugin registration order, which depends on concurrent module loading for otherwise independent plugins. That race produced different request headers in CI and snapshot recordings. Because order affects request bytes, caching, and the durable header, it needs an explicit deterministic policy.
## Decision
The system-prompt assembly owns the canonical model-facing tool order, exactly where it already owns section order. `toolOrder?: string[]` on `dsh-system-prompt` is the optional explicit policy:
- A listed tool that is registered takes its listed position.
- A listed name with no registered tool is a configuration error. Shape errors (rest entry missing or duplicate names) fail from the service constructor; an unregistered name rejects every `assemble()` — the earliest moment the registered tool set exists to check against (tool plugins register after the service constructs), and the only universal one (registrations can change at any time; cordis has no "all plugins loaded" event). Under the shipped loop the first turn fails before any model request — see the consequences below for the exact blast radius.
- A registered tool absent from the list is inserted at the `'<unlisted-tools>'` rest entry (`TOOL_ORDER_REST`), in lexicographic name order among the other unlisted tools.
- No collected tool may use `TOOL_ORDER_REST` as its `ToolSchema.name`; the assembly rejects that reserved name before ordering.
- The list must contain the rest entry exactly once and no duplicate names.
- When `toolOrder` is unset, the canonical order is plain lexicographic name order (code-unit comparison, locale-independent), so determinism requires no configuration.
`assemble()` canonicalizes provider tools before the `system-prompt/assemble` waterfall, removing registration-order variance at its source. The waterfall starts from this deterministic list; unchanged order then flows into the request header, frozen request, and reconstruction checks without loop-specific ordering logic.
Scope is deliberately narrow: this fixes the REGISTRATION-ORDER race, not plugin behavior. A `system-prompt/assemble` listener may still add, remove, or rearrange tools — same as it may edit sections after their sort — and owns the determinism of what it emits; the waterfall contract already demands deterministic listeners (the reconstructability invariant would catch a listener that diverges between build and replay).
Config plumbing follows the `persona` precedent, and `toolOrder` sits beside it: the app configs (`dsh-stdio-demo`, `dsh-acp-demo`) accept the key and forward it through `dsh-agent-spine-demo` (whose schema is the intersection of the owners' schemas) to the `SystemPrompt` child. One schemastery footnote is load-bearing: a schemastery array defaults to `[]`, but an omitted `toolOrder` must stay ABSENT (= lexicographic) rather than become an explicitly-configured empty list (invalid — it lacks the rest entry), so every schema on the chain forces the default to `undefined`.
## Alternatives considered
- **Registration order (the status quo)** — a concurrent-import race, host-dependent (the CI flake above), invisible in review.
- **A linearization of the plugin dependency graph** — the relation is partial and independent tool plugins are incomparable; the flake happened with the partial order fully satisfied.
- **Per-plugin `weight` on each tool contribution** — scatters the order across plugins yet still needs a global numbering convention nobody owns (the section `order` bands show that coordination cost being paid by hand).
- **Sorting in `ToolRegistry.schemas()` (the registry layer)** — equally deterministic, but the registry is a membership store consumed by more than the assembly; ordering is a prompt-composition concern, and the assembly already owns the composition policy for sections.
- **A `LlmService` config + `orderTools()` method the loop calls before logging the header** — works, but adds a public service method and a loop edit solely to apply a policy at a distance; every future request composer must remember the call. Canonicalizing where the list is born makes an unordered list unrepresentable, with zero new surface.
- **Normalizing inside `llm.stream()`** — runs after the header event is logged (the flake survives) and rebuilds the deep-frozen envelope, silently disarming the reconstruction invariant.
- **An exhaustive list (no rest entry)** — every newly loaded tool plugin would break boot; the mandatory rest entry keeps unlisted tools deterministic and their position explicit.
- **A boot-time validation pass (a `SystemPrompt.assertToolOrderSatisfied()` called by `dsh-app-boot` after `loader.await()`)** — would turn the misconfiguration into a startup death instead of a first-turn failure, but costs a public service method plus a structural coupling from the generic boot glue to one service, and cannot replace the assembly-time check anyway (embedded callers never run app boot; registrations change after boot). No existing event can host the check either: cordis v4 has no ready-like event, `loader/entry-init`/`internal/status` fire mid-load (racy against tool registration, the very entropy this RFC kills), and the agent lifecycle events are no earlier than the assembly. One enforcement point at `assemble()` was judged worth the later failure moment.
## Consequences
- Every registry-built assembly starts with a deterministic tool order on every host; absent an expert listener that deliberately changes it, every `request/header` event and model request inherits that order. The CI-vs-local registration-order flip is structurally gone, and the default is lexicographic.
- The initial `PromptAssembly.tools` is canonical, so waterfall listeners start from the model-facing order; provider registration order is observable nowhere before that cooperative seam.
- A pure tool reordering between steps is representable only as a `request/header` `'fallback'` snapshot (the name-keyed `ToolsDelta` cannot express it); with a stable canonical order such reorders no longer occur in practice, so the fallback path stays a safety valve.
- The `toolOrder` key rides the app → `agent-core``SystemPrompt` forwarding chain, so deployments set it next to `persona` in the app config; `dsh-llm` and the agent loop are untouched.
- A misspelled or unloaded tool name in `toolOrder` fails the turn at prompt assembly, not the boot: the loop assembles inside the turn (after `turn/start`, before `step/start`), so the rejection reaches the turn's outer catch — the turn closes balanced with an `error` reason carrying the message, `agent/error` mirrors it, no step opens, no `request/header` is logged, no request reaches the adapter, and the agent returns to idle. Every turn fails identically until the config is fixed; the process itself stays up (matching the repo rule that explicit config references must not be silently ignored — the enforcement point is the assembly because no earlier universal moment exists).
- A tool provider that returns the reserved rest-entry name has the same prompt-assembly failure shape as an unknown listed name. This keeps the sentinel from becoming an ambiguous real tool and preserves the "never drops a tool" ordering contract.
## Testing
System-prompt tests cover lexicographic default order, listed/rest placement, provider-order independence, shared names, invalid lists, unknown or reserved names, the canonical pre-waterfall list, and the rule that listener-added tools are not re-sorted. Loop tests pin identical logged and dispatched order across registration permutations, forwarding through agent-core and both apps, deep-frozen requests, and balanced turn failure with no step, header, or adapter call for an unknown configured name. Snapshot replay keeps the full canonical list only in the pinned `text-turn` header; other fixtures continue to use `{{tools}}`.

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# RFC: The subprocess sandbox — confinement seam, native runners, escalation, and per-session modes
Status: implemented
## Problem
A coding agent needs this product path: bash subprocesses — and the hook commands that ride them — execute under a restricted file sandbox by default; if and only if the sandbox actually denies an operation, the model may request one user approval for that same operation and, once granted, retry it once with wider permissions. An every-tool boundary is deliberately NOT the claim: fs/web/todo execute in-process where an `execve` wrapper is meaningless (§ In-process tools), and the cross-family boundary is staged follow-up work (§ Deferred phases). Without a shared vocabulary, every tool reinvents approval fields, denial parsing, retry matching, and permission-state hints.
The harness is an SDK, so confinement must be a capability developers COMPOSE: whether to sandbox, and which backend per platform, belongs in the leaf `cordis.yml` as a first-class entry — not inside one executor's private machinery. And the first-choice runner, `bwrap`, is unusable on exactly the hosts a sandbox matters most (minimal containers, disabled unprivileged userns, LSMs that deny `mount`), so a fallback runner has to ship with the SDK rather than be assumed on the host.
Confinement alone leaves two gaps. A denial with no escalation path is terminal — the model can only give up, which pressure-cooks operators into configuring `workspace-write` or `danger-full-access` globally and defeats the sandbox. And the model-visible knobs (the sandbox mode, the approval policy) change over an agent's lifetime — an ACP user flips a per-session setting, an operator edits `cordis.yml` while the process is down — while the model must never act on a stale belief about them: what IS the state on every request, what changed while the agent lives, and what changed while nobody was watching all need answers.
## Decision
One seam, one per-platform chain of local backends, one consumer, and two levers on top: a per-call escalation path and per-session runtime modes. Everything below composes from the leaf `cordis.yml`; nothing touches `agent-loop`. The scope is deliberately bounded: the phases this RFC names but does not design — per-session workspace root, cross-family fs enforcement, the `subagent-acp` consumer, more environments, a Windows chain — are listed under § Deferred phases, each a follow-up design, not a config knob.
### How a deployment uses it
Four `cordis.yml` entries turn an unconfined coding agent into the sandboxed product path; [`examples/acp-agent`](../../../../examples/acp-agent/README.md) uses this composition by default:
```yaml
- id: sandbox
name: '@deepseek-ai/dsh-sandbox-local' # the per-platform runner provider (ctx.sandbox)
- id: bash
name: '@deepseek-ai/dsh-bash-sandbox' # the confined executor, replacing dsh-bash-local behind ctx.bash
config:
mode: workspace-write # the deployment default every session starts from
workspaceRoot: !!js process.cwd() # the boundary workspace-write may write under
- id: approval
name: '@deepseek-ai/dsh-user-approval' # the escalation gate's channel (the approval RFC)
config:
policy: ask
- id: permission
name: '@deepseek-ai/dsh-permission' # one product-facing select over both mechanism knobs
```
The swap is invisible to every consumer of `ctx.bash`: the bash tools, hook commands, and background tasks run exactly as before, spawned through the wrapped argv the provider returns. Deleting the `sandbox` and `permission` entries and replacing `bash` with `@deepseek-ai/dsh-bash-local` is the opt-out — execution is unconfined again and the escalation fields vanish from the tool schema, because they are capability-gated on the mounted executor, not on configuration. Omitting only `approval` keeps confinement but fails every escalation closed with its own error text; `permission` also requires the approval seam and a confining executor, so a partially composed preset layer fails loud at load.
Misconfiguration fails loud: `mode` outside the closed vocabulary is rejected at plugin load, and a host with no usable backend throws the structured `SANDBOX_UNAVAILABLE` — at `confine()` before the command ever spawns — rather than degrading to unconfined execution. `runnerCommand` on `dsh-sandbox-local` is the operator's explicit assertion of a bwrap-compatible runner (chain and probes skipped); it doubles as the deterministic fake-runner seam for keyless tests.
Denied file effects return a `[sandbox: file access denied under <mode> mode]` marker and instructions not to work around the denial. A confining executor adds paired `sandbox_permissions` and `justification` fields for one approved retry that must be strictly wider than the session's effective mode. A grant widens only that retry; rejection executes nothing, returns `the user rejected escalating this command to "<mode>"`, and permits no re-ask. The prompt does not announce sandbox mode, avoiding preemptive refusal. When `dsh-permission` is composed, ACP exposes one `Permissions` select whose presets write both knob events; unmatched knobs appear as switch-away-only `custom`. Only a switch to the deterministic `'never'` approval policy is stated in the prompt and narrated.
### Design detail
#### Scope grounding
OS subprocess confinement applies to the bash executor, including hook commands, and later to ACP subagent children. Filesystem, web, and other tools execute in-process and require policy at their own seams; an argv wrapper cannot confine a function closing over `ctx`. The existing bash request/spec split carries per-call overrides, while `tools/pre-execute` and the approval seam own the human decision.
#### The seam: `ctx.sandbox`
`dsh-sandbox` owns the vocabulary and the `SandboxProvider` contract: `confine(argv, policy)` returns the argv to spawn INSTEAD of the caller's own — wrapped so the process and everything it spawns run confined — plus the `enforcement` completeness the selected backend achieves, its denial dialect (`denialSignatures`, the stderr substrings that backend's kernel prints on a denied file effect), and its runner-failure dialect (`runnerFailureSignatures`, how the runner ITSELF failing — and therefore the command never running — identifies itself); with no usable backend it throws the fail-closed `SANDBOX_UNAVAILABLE` error, never a silent unconfined passthrough. The vocabulary: `SandboxMode` (`read-only` / `workspace-write` / `danger-full-access`, FILE effects only — network and process visibility are not claimed), `SandboxEnforcement` (`full` / `partial`), `SandboxPolicy` (mode + workspace root).
Policy rides each CALL, not the provider: two consumers may confine under different policies at the same instant (bash under `read-only` while a confined child agent keeps its state directory writable), and an approved escalated retry is a new call with a wider policy — inexpressible under a config-fixed provider mode.
The seam confines SAME-WORLD subprocesses only: a backend shares the host's filesystem and kernel. Containers, microVMs, and remote executors are NOT backends of this seam — they replace whole capability implementations (`ctx.bash`, `ctx.fs`) as environment-coherent groups, because an agent whose bash runs in a container while its fs tools write the host lives in two split worlds.
Left open, for the phase that needs them: whether network restriction arrives as a separate `network_mode` or merges into `sandbox_mode` once a runner enforces both, and whether `SandboxPolicy` grows extra writable-root grants now (the launcher already speaks `--rw <path>`) or only when escalation needs them.
#### Local backends and the shipped launcher
`dsh-sandbox-local` selects one platform runner per provider lifetime and caches the verdict. Linux functionally probes `bwrap` then Landlock; macOS uses Seatbelt. Unsupported platforms and unusable runners fail closed. Each wrap carries backend-specific denial and runner-failure signatures so `dsh-bash-sandbox` can distinguish a denied file effect from a broken sandbox. `runnerCommand` skips selection as an operator assertion of a bwrap-shaped runner, but missing or unexecutable commands still classify as sandbox failure and never run the payload unconfined.
The launcher is a ~300-line C program (plain C11 over the raw Landlock UAPI — no libraries beyond a statically linked musl, so the audit surface is that one file plus the kernel's stable syscall contract): `--ro <path>` / `--rw <path>` grants, `--`, the wrapped argv; it installs the ruleset on itself and `exec`s (rulesets are inherited across `execve`, and it sets `no_new_privs` before restricting); `--probe` enforces a maximal ruleset in a short-lived child and exits 0 only when the kernel actually enforces; launcher failures exit 125 without exec'ing.
The Landlock launcher ships through [`node-addon-landlock-run`](https://www.npmjs.com/package/node-addon-landlock-run), with platform binaries selected by npm. That package owns path resolution, probing, and CLI flags; the harness maps sandbox modes to grants. Versioning the entry point with its binaries keeps probe parsing and launch syntax aligned.
FIXME: Revisit the separate-repository boundary and try to maintain the launcher source and its platform package family inside this monorepo, so the native release surface and harness contract evolve together.
Backend profiles share the mode contract but differ in necessary host grants. Landlock and Seatbelt allow only `/dev/null` in read-only mode; workspace-write also permits their required host temp roots. Each wrap carries backend-specific denial signatures. Landlock reports partial enforcement on older ABIs that cannot govern every operation, while successful bwrap and Seatbelt profiles report full enforcement.
#### The bash consumer
`dsh-bash-sandbox` extends `LocalBashExecutor` and hands `ctx.sandbox` the exact `['bash', '-c', command]` argv it is about to spawn. A denial is an orthogonal result fact, conservatively classified from the active runner's stderr dialect. A runner failure outranks denial: foreground execution throws `SANDBOX_UNAVAILABLE`; a settled `BashProcess` stamps `sandbox.runnerFailed`, and the bash producer renders it through generic `task_output`.
The model's view is result facts only: the static tool description explains the denial marker (`[sandbox: file access denied under <mode> mode]`), encourages attempting commands that may be denied, and forbids retrying around a denial; when the escalation fields are advertised, a denied result additionally carries the escalation hint itself, so the sanctioned same-turn retry is prompted at the decision point rather than depending on the model recalling the description (§ Escalation). No prompt section states the sandbox mode (§ Per-session modes).
#### Escalation: one approved wider retry after a denial
`BashExecRequest.sandboxMode` is an optional per-call input; resolved specs make the field explicit. `BashExecutor.sandboxMode` advertises whether the mounted executor can honor it, so only a confining composition exposes escalation. The seam accepts any explicit mode; the tool owns the wider-only escalation rule. Non-sandboxing executors remain honestly unconfined.
`SandboxBashExecutor.resolve()` stamps the effective mode — escalation grant > session override > configured default — so `run()`/`start()` read the spec, never the config. Per-process wrap facts are keyed by the returned `BashProcess`; `onProcessDone()` classifies stderr and stamps that handle before `done` resolves, so overlapping processes retain their own modes and runner dialects.
When a confining executor is mounted, `bash` advertises paired `sandbox_permissions` and `justification` fields. The schema exposes the full closed escalation vocabulary because effective mode is per-session; execution rejects any target that is not strictly wider than that call's effective mode. Approval resolves before execution. `allowed-once` stamps the granted mode onto only that request, while `rejected`, `cancelled`, `unavailable`, a missing approval service, or a missing agent all fail closed with distinct results. No grant is persisted.
Escalation is a same-turn retry of the denied command with the narrowest sufficient `sandbox_permissions` and a `justification`; the approval prompt is the consent step. It must be grounded in an actual denial, except when the session already observed the same denied access, and a disabled or rejected approval ends that command. The retry, approval decision, and result use existing tool and approval events. `dsh-tool-bash` owns the ask because the executor seam has neither the agent nor call id required for user interaction.
Left open: what a durable grant's scope identity is beyond the sandbox mode — exact call, path, command prefix, session, or time window — before an `allow_always` option can be advertised.
#### Per-session modes: the session log as the store
```
effective(session) = findLast(the session's own knob events)?.value ?? the composition-config default
```
The default is composition config (`cordis.yml`) — operator-owned, process-wide. A runtime switch is a SESSION-SCOPED override recorded as one log-only event in that session's own log. Restart immunity (resuming a session replays its log, so overrides come back with zero catch-up machinery) and multi-session isolation (one editor tab's `workspace-write` cannot disturb another's `read-only`) both fall out by construction, and no external config store exists anywhere.
**One event per knob, owned by its domain** — the merge-extensible `SessionEventMap` idiom every existing event family already follows (`approval/*` in `dsh-user-approval`, `hook/*` in the hooks packages):
```ts
interface SessionEventMap {
'bash/sandbox-mode': { mode: 'read-only' | 'workspace-write' | 'danger-full-access' }
'approval/policy': { policy: 'ask' | 'never' }
}
```
Each owner exports the same three-piece kit: the event declaration, a pure fold (`effectiveSandboxMode(events)` / `effectiveApprovalPolicy(events)` — a `findLast`, typed to the domain's closed union), and THE write path (`setSandboxMode(session, mode)` / `setApprovalPolicy(session, policy)` — a switch IS its event; nothing mutates state out of band). No shared owner service, no generic facts map, no registry: a third knob copies the ~40-line pattern into its own package. Execution follows the fold on both sides — the bash tool's per-call stamp reads it as the middle rung of the § Escalation precedence chain, and the approval seam's `'never'` gate is [the approval RFC](2026-07-06-approval-seam.md)'s side of the same pattern.
Sandbox mode is not narrated in the prompt; denial results report the mode when it matters, avoiding preemptive refusal based on a standing label. Approval policy is different: only `'never'` is stated because automatic rejection otherwise looks like a user decision. Policy-change notices are coalesced and delivered by the next pre-step, with log-derived fallback after restart. The notice source is inferred from event position: a knob event after the last request header is user-driven; unlogged drift is operator or config driven.
**The editor surface** is protocol-native [Session Config Options](https://agentclientprotocol.com/protocol/session-config-options) — the spec's replacement for session modes (slated for removal in ACP v2), already SDK-typed. When `ctx.permission` is composed, the bridge advertises one `permission` select (category `mode`) in `session/new` and `session/load`; its options are the deployment's preset table, and its `currentValue` is `PermissionService.current()` over the session log plus composition defaults. The shipped `workspace-write` and `danger-full-access` presets each bundle a sandbox mode with an approval policy and write through to both domain setters; a knob combination outside the table is reported as switch-away-only `custom`. `session/set_config_option` validates and switches through the permission service, then returns the complete refreshed state (the spec contract).
**Turn enclosure is the commit boundary.** A switch during an open turn appends immediately. An idle switch remains pending on the bridge record and is appended at the next prompt submission, before assembly or execution; last write wins per knob. Openness comes from log boundaries rather than `agent.status`, and setters do not append from inside a `session/event` listener because that would reorder later observers. Until anchoring, responses overlay the pending value. A crash discards it, and reload returns the durable fold.
#### In-process tools
fs/web/todo execute in-process, so their sandbox semantics are policy at their seams: the fs intent gates deciding by the shared mode vocabulary (§ Deferred phases, cross-family) make `read-only` a real boundary instead of a bash-only approximation — until then the contract says so honestly. No generic per-tool sandbox runtime: a host-mediated tool leaves the process only by returning declarative effects the host validates, which is a rewrite, not a wrapper.
FIXME: Revisit this tool-local boundary. The follow-up design needs to determine whether sandboxing becomes a global harness capability that applies uniformly to every tool, instead of expressing in-process enforcement independently at each tool seam.
### Testing
- **Unit:** pin platform selection and profiles, fail-closed runner classification, per-call facts, escalation validation and outcomes, permission preset folding and write-through, narrator coalescing, ACP advertisement and validation, and turn-enclosed config writes.
- **Keyless real-runner:** exercise bwrap, Landlock, and Seatbelt against real filesystem effects at provider and bash-consumer layers; packed-install coverage proves the registry launcher remains executable. The real ACP composition pins permission switching and rejects unknown presets. CI rejects a silent all-skip.
- **With-key:** drive a real model, runner, bridge answerer, and disk effect through granted and rejected escalation; unavailable credentials or runners self-skip.
- **Snapshot:** pin the permission config-option wire, preset and knob events, prompt deltas and notices, and both scripted approval branches. Snapshot mode starts unconfined so unrelated fixtures remain platform-independent; policy scenarios switch explicitly. Real denial stderr stays on platform tests because its dialect is runner-specific.
## Deferred phases
Each phase gets its full design when picked up, validated against the code at that time, and lands with unit, real-API e2e, and snapshot coverage at the tiers it touches.
- **Per-session workspace root** — the executor's write boundary stays config-fixed for its lifetime while each ACP session has its own cwd; a per-session root rides the same per-call policy carrier once designed.
- **Cross-family boundary** — the fs intent gates decide by the shared mode, making `read-only`/`workspace-write` real boundaries beyond bash.
- **Second consumer** — `subagent-acp` optionally confines child agents (per-call policy; unconfined default — a child agent must write its own persistence).
- **More environments** — an environment-coherent capability group example (e.g. bash+fs against one container).
- **Windows chain** — `PLATFORM_CHAINS.win32` is reserved and empty (fail-closed); filling it means a confinement runner from the AppContainer/restricted-token family, shipped from its own repository on the `node-addon-landlock-run` template, plus its profile dialect and denial/runner-failure signatures.
## Alternatives considered
- **Command-string heuristic preflight** — rejected: cannot understand expansion/subprocesses/symlinks; the strict attempt (run it, let the kernel decide) is the only trustworthy denial signal.
- **Functionally probe even a platform's sole backend** — rejected: probing arbitrates between candidates; with one there is nothing to decide, and probe cost taxes the first confined command of every session (prohibitive for heavy future backends). The runner's own exec-time fail-closed refusal plus `runnerFailureSignatures` classification carries the safety property instead.
- **Commit the built launcher binaries** — rejected: a binary in a diff is unreviewable and churns history; reviewed source + native CI builds + the launcher repo's byte-pinned publish rehearsal keep bytes out of every tree.
- **Compile the launcher on install** — rejected: pushes a C toolchain onto every consumer; a fallback that exists only where a compiler happens to be is not a fallback.
- **Cross-compile both architectures from one builder** — rejected: requires carrying a pinned cross toolchain (rustup targets, zig, or a container image) solely to rebuild two ~70 KB binaries; per-architecture native runners already exist and each builds its own platform package (the `node-addon-require-builtin` model, the launcher repo's own pipeline).
- **No fallback (bwrap or fail closed)** — rejected: concentrates failure on the hosts a sandbox matters most, degrading to `danger-full-access` by resignation.
- **Keep the mechanism inside `dsh-bash-sandbox`** — rejected: blocks the existing second consumer, makes future phases read mode out of a bash plugin's config, and cannot express escalation.
- **Config-fixed mode on the provider** — rejected: one mode per process; cannot serve concurrent consumers with different policies nor the one-shot widened retry.
- **One interface spanning containers/VMs too** — rejected: `confine(argv)` presupposes a shared filesystem; environment isolation is capability-sibling backends deployed as coherent groups.
- **Generic ToolRuntime wrapping any tool** — rejected: mechanically false for in-process tools (closures over `ctx`); the declarative-effects rewrite is unjustified for fs/web/todo.
- **Ask inside the executor (`dsh-bash-sandbox`)** — rejected: no `agent` to route through, no `callId` to attach the prompt to; adding them teaches a transport seam about sessions and UIs — the tool layer holds both and owns the model-facing vocabulary.
- **Auto-retry inside the same tool call** — rejected: a hidden re-entry the log cannot reconstruct: one `tool/call` would have produced two executions with different policies — the retry is a NEW logged call with its own arguments and result facts.
- **Advertise the escalation fields unconditionally** — rejected: under `dsh-bash-local` they are a dead lever — advertising an option the harness cannot honor manufactures doomed grants; capability-gating costs one registration-time read.
- **A default-relative escalation ladder (advertise only the modes wider than the executor's registration-time default)** — rejected: per-session overrides make the default the wrong baseline — a session switched narrower than the default loses exactly the lever it needs, and under a `danger-full-access` default the fields vanish entirely while a `read-only`-overridden session stays confined with no escalation path. The enum pins the closed target vocabulary; strict widening is a per-call execution check against the session's effective mode.
- **Per-session dynamic tool schemas** — rejected: schemas are registry-global by design (one assembly vocabulary, the pinned-header snapshot contract), and re-registering per session would buy only what the execution-time strict-wider check already guarantees, at the cost of a per-session schema surface and header churn on every switch.
- **Hard-match the retry to a prior denial** — rejected: command-string identity is fragile (quoting, `workdir`, env prefixes, a pipeline retried as its failing stage) — false-rejects honest retries or is trivially satisfied; the real boundary is the human seeing command + justification. Revisit only if `allow_always` grant storage ever needs machine-checkable scopes.
- **A generic `env/state` facts map with an owner service** — rejected: approval and sandbox compose independently, so neither's state may drag in a third package; single-key folds are one `findLast` each, dissolving the owner service; no invariant spans the knobs, so atomic multi-key patches bought nothing.
- **Narrate via `agent/user-message` + a bus event** — rejected: it presupposes a turn-entry seam that does not exist (the real seam is `agent/prompt-submit`), and pre-step's position serves both the coalesced turn-entry notice and the mid-turn immediacy bound with one listener.
- **A standing prompt statement of the sandbox mode (+ a switch narrator)** — shipped first, then removed on live evidence: with `Bash commands run under the "read-only" file sandbox.` in every request, the model refused to ATTEMPT denied-then-escalatable work (five of twelve turns in the first manual session ended with zero tool calls), turning the sandbox into a soft lockout. The denial marker names the mode at the moment it matters and the escalation fields carry the recovery; the approval knob keeps its statement because an auto-rejection is behaviorally indistinguishable from a human "no".
- **Track "last told" with its own bookkeeping events** — rejected: the `request/header*` fold already records the exact prompt the model saw; parsing the closed candidate sentences back replaces a second bookkeeping stream — events are needed only where they ARE the store.
- **ACP session modes instead of config options** — rejected: the preset is already one deployment-defined config-option select, and modes are slated for removal in ACP v2.
## Consequences
What shipped pins — the tiers in Testing hold each:
- A denied command retried with `sandbox_permissions` + `justification` prompts the user through the composed answerer chain; a grant runs THAT call under the wider mode (result facts say so) while every other call keeps its own effective mode; every non-grant outcome produces its distinct error text and executes nothing.
- The escalation fields exist exactly when the mounted executor confines; a request that is not strictly wider than the call's effective mode fails closed with its own text and prompts no one; a deployment with no ApprovalService fails escalating calls closed and leaves plain calls untouched.
- The system prompt never states the sandbox mode (an approval `'never'` policy is the one stated knob), and the whole exchange — headers, knob events, notices, approvals, results — reconstructs from the session log alone, with no event types beyond the two knob events.
- N idle-time flips produce at most one anchored event per knob (a net-zero sequence anchors none — a no-op push from a client echoing current selections records nothing); an approval-policy switch is narrated in at most one coalesced notice; a mid-turn sandbox switch is honored by the next call's stamp.
- A resumed session's overrides apply and are reported to the editor with no special-casing; a default changed while the process was down is narrated before the session's first new request, attributed to the operator.
- Two concurrent sessions never see each other's state, notices, or config options.
- `agent-loop` is untouched — everything rides `systemPrompt.section`, `SessionEventMap` merging, `agent.inject()`, `agent/pre-step`, `agent/prompt-submit`, and the ACP handler surface.
Costs and accepted limits:
- **The one-wrapper illusion is given up knowingly.** A `tools/pre-execute` wrapper plus prompt conventions does not solve sandbox approval — the correct design costs structured denials, native runner probes, per-call policy carriage, and consistent cross-family enforcement, and this design pays it.
- **`read-only` is not yet a cross-family boundary.** Until the fs intent gates decide by the shared mode, the claim holds for bash only; the contract says so honestly (§ In-process tools).
- **Windows has no backend.** Its chain slot is reserved empty — fail-closed, never a fallthrough; filling it is a deferred phase.
- **The Seatbelt rung leans on Apple's deprecated-but-shipped `sandbox-exec` CLI.** As darwin's sole candidate it is selected without probing, so a future removal surfaces at execution as the runner-failure classification — re-thrown `SANDBOX_UNAVAILABLE`, the command never runs; fail closed, never open.
- **Landlock confinement is only as complete as the running kernel's ABI.** Reported as `enforcement: 'partial'` rather than refused — the deliberate trade that keeps the fallback available on older-kernel hosts.
- **The launcher arrives as a registry dependency.** Trusted through its own repository's release pipeline (reviewed C source, native CI builders, byte-pinned publish rehearsal) plus this repo's version pin — the real-kernel e2e legs are what vouch for behavior through the installed bytes.
- **The model may over-ask.** Escalating without denial grounding, or picking `danger-full-access` where `workspace-write` suffices: the description steers and the enum forces the ladder, but the human prompt is the actual gate; the `approval/asked` reasons make over-asking auditable, and a `prepend` policy answerer can auto-reject patterns a deployment never wants.
- **The advertised target set is static while the effective mode is per-session** (schemas are registry-global) — a session already at the widest mode is still offered the fields. Harmless by construction: the strict-wider check at execution, not the enum, is the safety boundary — a non-widening request fails with its own text and never prompts anyone.
- **A granted escalation is not a working sandbox.** An unavailable backend still fails closed even for a granted escalation to a confining mode — at `confine()` when the platform has no chain or every probe fails, at execution when an unprobed sole runner refuses (classified as a sandbox failure, not a command failure) — while a granted `danger-full-access` run never touches the provider at all: there the grant, not the probe, is the authority.
- **An idle switch lives in bridge memory until the next prompt submission anchors it.** A crash in that window reverts it (reported on `session/load`), and a session that never submits another prompt never persists it — accepted, with a loop-owned idle commit turn left as future work if durability becomes required.
- **The approval narrator's restart baseline parses prompt prose.** The closed candidate sentence is owned by the writing module itself, so a wording change is a coordinated writer+parser edit in one file; a session whose headers predate the section silently adopts the current policy without a notice.
- **The approval section is still a dynamic prompt surface** (a `'never'` switch breaks provider prompt-prefix caching for that session). Accepted: policy switches are rare, and a model acting on a stale `'never'` is worse. The sandbox knob no longer touches the prompt at all.
- **The model may hold a stale belief about the sandbox mode** (nothing announces a switch). Accepted deliberately: the next attempt's marker or success corrects it, and the observed failure mode of announcing — preemptive refusal — is worse than one wasted retry.
## FAQ
- **A command came back with `[sandbox: file access denied under read-only mode]` — did it fail?** It RAN, and the kernel refused a file effect: the denial is a result fact orthogonal to exit code. The teaching forbids retrying around it; the one sanctioned move is the same command retried once with an escalation request.
- **How is a BROKEN sandbox told apart from a failing command?** Runner failure outranks denial in classification: a failed run matching the wrap's `runnerFailureSignatures` means the command NEVER ran — foreground re-throws the structured `SANDBOX_UNAVAILABLE` with the runner's stderr line, a background task stamps `sandbox.runnerFailed` and renders its own marker. A broken sandbox can never read as a failing command, and the command never runs unconfined.
- **What happens on a platform with no backend — Windows today?** `confine()` throws the fail-closed `SANDBOX_UNAVAILABLE` and the command never spawns; `win32` is a reserved EMPTY chain, pinned by test to fail closed identically until a Windows runner fills it (§ Deferred phases).
- **`bwrap` is installed on my host but unusable (disabled unprivileged userns, an LSM denying `mount`) — what happens?** The chain probe is functional — it builds and enforces a real profile rather than checking `--version` — so a present-but-unusable `bwrap` fails its probe, selection falls to the registry-installed Landlock launcher, and the verdict is cached for the provider's lifetime.
- **Does the sandbox restrict network or process visibility?** No — `SandboxMode` claims FILE effects only; the bwrap profile deliberately does not unshare pid, and no backend claims network. Whether network restriction becomes its own knob is left open in § The seam.
- **Which tools actually run confined?** OS subprocesses through `ctx.bash` — the bash tools, and hook commands transitively. fs/web/todo execute in-process, where an `execve` wrapper is mechanically meaningless; their `read-only` semantics arrive with the cross-family deferred phase, and until then the contract says bash-only honestly.
- **Does a granted escalation persist?** No. The grant is consumed by the exact foreground or background call that asked; every neighboring call keeps its own effective mode. A later background denial surfaces through `task_output` and may ground a new exact-command retry.
- **When does an editor's mode switch take effect?** Mid-turn: appended immediately, honored by the very next call's stamp. Idle: held on the bridge's session record, anchored at the next turn's `agent/prompt-submit`, with N flips coalescing to at most one event (none if net-zero); a crash before anchoring reverts it and `session/load` reports the truth. The model is not told — its next command simply behaves under the new mode.
- **What survives a restart — and what if the operator changed the config default while the process was down?** Overrides replay from the session log (`effective = fold ?? config`), so a resumed session keeps its modes with zero catch-up machinery; a default that drifted offline changes behavior the same way a switch does (the approval policy, being stated, is additionally narrated with operator/config attribution).
- **What does `enforcement: 'partial'` on a result mean?** The selected backend enforces the subset its kernel ABI governs — e.g. Landlock before ABI v3 does not govern path truncate — and says so structurally instead of refusing the host; the probe's report line distinguishes the cases. The bwrap and Seatbelt profiles govern every promised file effect by construction, so they always report `full`.
## Prior art
In-repo precedents this design copies or contrasts with:
- [The capability-seams RFC](../architecture/2026-06-13-capability-seams.md) — the interface/implementation/consumer split and the "don't split preemptively" timing rule the second consumer satisfied.
- The `dsh-bash` request/spec split ([the bash vocabulary catalog](../../../core-data-structures/bash.md)) — the per-call carrier template `sandboxMode` rides, and the explicit-`resolve()` defaulting convention.
- [The approval seam RFC](2026-07-06-approval-seam.md) — the channel escalation asks through; its answerer waterfall, audit pair, and one-package rationale are recorded there.
- [Event-sourced sessions](../architecture/2026-06-11-event-sourced-sessions.md) and [the turn-enclosure invariant](../architecture/2026-06-15-turn-enclosure-invariant.md) — the log-as-store foundation the per-session modes fold over, and the commit boundary the anchoring design obeys.
- [The interception-seams RFC](2026-06-30-interception-seams.md) — the `tools/pre-execute` vocabulary the escalation gate deliberately does not reuse (an escalating call has no pre-execute moment of its own).

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# RFC: MCP client plugin — connect to external MCP servers and bridge their tools
Status: implemented
## Problem
The harness had no way to consume tools from the MCP (Model Context Protocol) ecosystem. MCP is the emerging standard for tool servers — GitHub, filesystem, databases, code search, and hundreds of community servers expose tools via MCP. Users want to point the harness at one or more MCP servers and have their tools appear as native model-facing tools, without writing per-server glue code.
The `ToolRegistry` already accepts raw JSON Schema tool definitions (documented in `dsh-tools` README: "Raw JSON-Schema tool definitions (from MCP servers) are still accepted by `ToolRegistry.register()` directly"), and the extension cookbook sketches the intended pattern ("MCP | one plugin per server: discover tools → `ctx.tools.register()`"). The infrastructure was ready; the bridge plugin was missing.
## Decision
### Package
A single package `@deepseek-ai/dsh-mcp-client` at `packages/mcp/mcp-client/`. No capability-seam three-package split — there is no foreseeable second MCP client implementation, and the convention is "don't split preemptively" ([capability seams RFC](../../implemented/architecture/2026-06-13-capability-seams.md)).
### SDK
Use the official [`@modelcontextprotocol/sdk`](https://github.com/modelcontextprotocol/typescript-sdk) (`Client`, `StdioClientTransport`, `StreamableHTTPClientTransport`). The harness does not implement its own JSON-RPC — consistent with how ACP delegates to `@agentclientprotocol/sdk`.
### Scope
MCP Client only (no server side — ACP already covers the "expose harness as an agent" role). Bridge **Tools** only — Resources and Prompts are deferred (they require harness-side consumption mechanisms that don't exist yet, and design space is large).
### Plugin shape
Namespace plugin (named exports `name`/`inject`/`Config`/`apply`, no `export default`). `inject: ['tools']`. Each MCP server is one plugin instance in `cordis.yml` — the same package loaded N times with different configs, like `dsh-tool-subagent`.
### Configuration
Flat discriminated union on the `transport` field:
```typescript
interface StdioConfig {
transport: 'stdio'
serverName: string // required namespace, ^[A-Za-z0-9_-]{1,32}$
command: string
args?: string[]
env?: Record<string, string>
cwd?: string
toolCallTimeoutMs?: number // default 60_000
}
interface StreamableHttpConfig {
transport: 'streamable-http'
serverName: string // required namespace, ^[A-Za-z0-9_-]{1,32}$
url: string
headers?: Record<string, string>
toolCallTimeoutMs?: number // default 60_000
}
type Config = StdioConfig | StreamableHttpConfig
```
`serverName` is the stable local identity that namespaces this server's tools in the model-facing name (below). It is deliberately user configuration, NOT the remote `serverInfo.name`: the remote name is untrusted input, is not unique across deployments (prod and staging instances of one server report the same name), and may change on server upgrade — none of which may silently rename model-facing tools. A duplicate `serverName` across live instances is a configuration error: the later instance fails at load with an actionable message, never silent shadowing or skipping. A short `serverName` (`gh`) is also the knob for shortening public names.
Example `cordis.yml` usage:
```yaml
- id: mcp-github
name: '@deepseek-ai/dsh-mcp-client'
config:
serverName: github
transport: stdio
command: npx
args: ['-y', '@modelcontextprotocol/server-github']
env:
GITHUB_TOKEN: !!js process.env.GITHUB_TOKEN
- id: mcp-web
name: '@deepseek-ai/dsh-mcp-client'
config:
serverName: web
transport: streamable-http
url: http://localhost:3000/mcp
headers:
Authorization: !!js `Bearer ${process.env.MCP_TOKEN}`
```
The model sees `mcp__github__create_issue`, `mcp__github__search_code`, `mcp__web__search`.
### Lifecycle
Boot-time from `cordis.yml`. HMR (`@cordisjs/plugin-hmr`) provides hot-swap: editing the yml entry triggers dispose of the old instance (disconnects, unregisters tools) and creation of a new one (connects, discovers, registers). No runtime-dynamic API for now. Public names are pure functions of `(serverName, rawName)`, so an HMR swap that keeps `serverName` recreates identical model-facing names — session history and permission rules stay valid — and adding or removing an unrelated server never renames an existing tool.
### Tool discovery and registration
Every MCP tool has two names:
- `rawName` — the exact MCP `Tool.name`, used only on the wire (`tools/call`).
- `publicName` — the globally unique model-facing name registered in the `ToolRegistry`:
mcp__<serverName>__<rawName>
This server-qualified shape is the de-facto standard among multi-server agent clients — every surveyed end-user product qualifies MCP tools by server ([Claude Code](https://code.claude.com/docs/en/agent-sdk/mcp#tool-naming-convention) `mcp__github__list_issues`, [Codex](https://openai.com/index/unrolling-the-codex-agent-loop/) `mcp__weather__get-forecast`, [Gemini CLI](https://geminicli.com/docs/tools/mcp-server/#3-tool-naming-and-namespaces), [VS Code](https://github.com/microsoft/vscode/blob/ab9ec62c6a61e429a9abd612ff220c3f4834c9ea/src/vs/workbench/contrib/mcp/common/mcpServer.ts#L217-L260), [Cline](https://github.com/cline/cline/blob/52fdbb1d72f7324a28142a7ba7678d4b53c902f4/sdk/packages/core/src/extensions/mcp/name-transform.ts#L20-L35), [Roo Code](https://github.com/RooCodeInc/Roo-Code/blob/b867ec9145750d0ae1ff7f02d35406e9bf2a0b16/src/utils/mcp-name.ts#L117-L140), [Goose](https://github.com/block/goose/blob/b3a012cbdde854b0fe14f95b1c48543bf6517c0a/crates/goose/src/agents/extension_manager.rs#L1391-L1441), [OpenCode](https://github.com/anomalyco/opencode/blob/d199b1bff90282a4f9cd6251b5fc7b16875a52f6/packages/opencode/src/mcp/catalog.ts#L117-L120)); the exact `mcp__<server>__<tool>` spelling follows Claude Code and Codex. The `mcp__` marker keeps MCP registrations out of the native tools' namespace and gives permission/telemetry rules a stable shape (`mcp__*`, `mcp__github__*`).
1. On connect: drain `client.listTools()` pagination, derive every tool's `publicName`, then register each as a raw `ToolDefinition` via `ctx.tools.register()`. The MCP JSON Schema and description pass through unchanged (no `defineTool` DSL conversion); only the model-facing `name` is replaced.
2. Listen for `notifications/tools/list_changed` → re-run the same sync (dispose previous generation, register new). Deterministic names mean unchanged tools keep their names across re-syncs.
3. The executor closes over `rawName`; the public name is never sent to the server and never parsed to recover the raw name.
4. No `presentCall`/`presentResult` — the ACP bridge's generic-card fallback handles rendering.
5. Tools are transparent in the system prompt — no "[via MCP]" annotation beyond the name itself.
### Public name normalization
MCP allows tool names up to 128 characters including `.`; the DeepSeek function-name contract allows `[A-Za-z0-9_-]` and at most 64. Public names are normalized deterministically: invalid characters become `_`, and when replacement or truncation changed the name, a 12-hex-char SHA-256 hash of the `(serverName, rawName)` identity is appended so distinct MCP identities can never collapse into the same public name:
```typescript
function publicToolName(serverName: string, rawName: string): string {
const joined = `mcp__${serverName}__${rawName}`
const normalized = joined.replace(/[^A-Za-z0-9_-]/g, '_')
if (normalized === joined && normalized.length <= 64) return normalized
const hash = sha256(`${serverName}\0${rawName}`).slice(0, 12)
return `${normalized.slice(0, 64 - 13)}_${hash}`
}
```
### Name conflict handling
MCP guarantees tool-name uniqueness only [within one server](https://modelcontextprotocol.io/specification/2025-11-25/server/tools#tool-names); cross-server collisions are the norm, not the exception (a [Microsoft Research survey](https://www.microsoft.com/en-us/research/blog/tool-space-interference-in-the-mcp-era-designing-for-agent-compatibility-at-scale/#namespacing-issues-and-naming-ambiguity) of 1,470 servers found 775 colliding tool names; `search` alone appears in 32 servers, and the official GitHub server publishes bare `create_issue`). The always-on namespace makes collisions structurally impossible instead of handling them at collision time:
- Two servers publishing `search` coexist as `mcp__github__search` and `mcp__web__search`.
- A native harness tool named `search` is unaffected.
- Duplicate `serverName` config fails the later instance at load (see Configuration).
- A server listing the same tool name twice is an invalid tool list: the sync throws and the previous generation stays registered.
- A registry conflict during the swap can only mean a foreign tool squats on this server's `mcp__<serverName>__` namespace: the partial generation is rolled back (zero tools from this server) and the error is logged loudly.
Tools are never silently skipped; which tools are available never depends on plugin load order.
### Naming invariants
1. Every MCP tool has the stable identity `(serverName, rawName)`; every active identity has exactly one public name.
2. Public names are deterministic, globally unique, and satisfy the DeepSeek 64-char `[A-Za-z0-9_-]` contract.
3. MCP `tools/call` always receives the original raw name.
4. Connecting, disconnecting, or re-syncing an unrelated server never renames an existing tool.
5. Registration order never determines which tool is available.
### Tool execution
A unified `execute` handler for all tools from one MCP server:
1. Resolve `rawName` (the executor closes over it) and call `client.callTool({ name: rawName, arguments }, { signal: exec.signal })` with the configured timeout — the public name is never sent to the server.
2. Map the result:
- Multiple `text` content blocks → join with `'\n'` into a single `TextBlock` (required: `flattenText` uses `join('')` without separator, so multiple blocks would lose inter-block boundaries).
- `image` content blocks → discard with a `ctx.logger.warn` (the harness has no image content block type; [drop-image RFC](../../implemented/simplification/2026-07-04-drop-image-content-block.md)).
- `isError: true` → map to the harness `isError` result path (`{ content: [...], isError: true }`).
3. Cancellation: `exec.signal` (from the agent loop's cancel) is passed through to the MCP SDK's `callTool`, which sends `$/cancelRequest` to the server.
### Subprocess environment (stdio transport)
Replicate the `buildChildEnv` + `SENSITIVE_ENV_PATTERN` scrub from `dsh-subagent-acp`: filter ambient env (strip credential-shaped vars matching `/KEY|SECRET|TOKEN/i`), then merge `config.env` on top. Explicit env overrides survive the scrub.
### Disconnection / crash
No auto-reconnect. If the MCP server process exits or the transport closes:
1. The effect disposes → all registered tools are unregistered (fiber-scoped disposers).
2. Subsequent model calls to those tools → `ToolNotFoundError``isError: true`.
3. Recovery: user edits `cordis.yml` (triggers HMR reload) or restarts the harness.
This matches the ACP subagent pattern: "crash = terminal, report error, clean up, don't retry."
## Alternatives considered
### MCP Server side (expose harness tools to external MCP clients)
Deferred. The ACP bridge already exposes the harness as an agent server. Adding an MCP server layer would duplicate that with a different protocol, and the primary user need is consuming external tools, not exposing them.
### Capability-seam three-package split (interface / impl / consumer)
Rejected. There is no foreseeable alternative MCP client implementation — MCP has one protocol, one SDK. The convention is "don't split preemptively" until a second implementation appears.
### Auto-reconnect with exponential backoff
Rejected for v1. Adds complexity (partial-availability state where tools are registered but temporarily non-functional), and stdio process crashes usually indicate a configuration problem that retrying won't fix. HMR already provides the manual recovery path. Can be added as a future `reconnect: boolean` config if needed.
### Bridge Resources and Prompts
Deferred. Resources need a harness-side mechanism to decide WHEN to inject content (system prompt? on demand? model-triggered?). Prompts need a "prompt template" concept the harness lacks. Both require their own design; Tools are the high-value, low-risk starting point.
### Raw model-facing tool names with an optional `toolPrefix`
Rejected — this was the original proposal, built on the premise that "most MCP servers already use semantic prefixes in their tool names (e.g. `github_create_issue`)". The premise is false: the official GitHub server publishes `create_issue`, the reference filesystem server `read_file`, Sentry `search_issues` — and the Microsoft survey above shows collisions are common at ecosystem scale. Collision-time prefixing (or warn-and-skip) also makes the available tool set depend on plugin load order, and a tool could be silently renamed when an unrelated server is added — invalidating session history and permission rules mid-conversation. No surveyed multi-server agent product ships raw names.
### Server-only namespace (`github__create_issue`, no `mcp__` marker)
Rejected for v1. It prevents cross-server collisions but does not separate MCP registrations from native harness tools, and it forfeits MCP-wide policy shapes (`mcp__*`). The marker costs 5 characters; the `mcp__<server>__<tool>` spelling matches Claude Code and Codex, maximizing model familiarity. If the ToolRegistry later grows source-aware namespaces, dropping the literal marker can be revisited as a naming-policy change.
### Deriving the namespace from the server-announced `serverInfo.name`
Rejected. The remote name is untrusted, non-unique across deployments, and changeable on upgrade; tool identity and permission rules must not silently follow it. The namespace is local configuration.
### Preserve multiple TextBlocks in tool result
Rejected. `flattenText()` in the DeepSeek serializer uses `join('')` (no separator) when flattening `ContentBlock[]` to wire format. Multiple text blocks would silently lose inter-block boundaries — a correctness bug. All existing tools return a single TextBlock; the MCP bridge follows suit.
## Testing
Coverage is named per tier; each behavior lives at the cheapest tier that can express it.
- **Unit** (`tests/mcp-client.spec.ts`, `tests/apply.spec.ts`, mocked MCP SDK): the `publicToolName` algorithm (clean, normalize, truncate-and-hash, determinism, distinct-identity separation), raw-vs-public wire discipline, cross-server and native-tool coexistence, duplicate-`serverName` load failure and reservation release, invalid-tool-list rejection, generation swap/rollback, failed-re-sync retention, result mapping, cancellation, config schema validation. 100% per-file coverage gates the package.
- **E2E** (`tests/mcp-client.e2e.ts`, keyless): the real MCP protocol against the in-repo fixture server, `@modelcontextprotocol/server-everything`, and `@modelcontextprotocol/server-filesystem` over stdio, and against an in-process `StreamableHTTPServerTransport` server over Streamable HTTP — discovery under the namespace, dotted-name normalization end to end, execution round-trips, duplicate-`serverName` rejection, disposal.
- **Snapshot**: deliberately none. MCP tools introduce no new transcript surface — they register as raw `ToolDefinition`s and render through the ACP bridge's generic-card fallback, which the bridge's unit suite already pins (`packages/ui/acp/tests/stream-update.spec.ts`). Adding an MCP server to the snapshot example's `cordis.yml` would mutate the pinned `text-turn` system-prompt fixture (forcing a with-key re-record of every recorded golden) and make every replay depend on spawning an external MCP server process — for zero new rendering behavior. If a later change gives MCP tools their own render intent, that change names its snapshot coverage then.
## Consequences
- A `cordis.yml` entry per MCP server is the entire integration cost: `serverName: filesystem` + a stdio command (or a Streamable HTTP URL) puts `mcp__filesystem__read_file` in the model's tool list, callable, with the raw `read_file` on the wire.
- Public names are part of session history and permission/config surfaces; the naming algorithm is a v1 contract pinned by tests, and changing it after release is a breaking change.
- The `mcp__<serverName>__` qualifier costs tokens on every name. Accepted: descriptions and JSON schemas dominate tool-definition tokens, and the qualifier buys stable identity, collision isolation, and MCP-wide policy shapes (`mcp__*`, `mcp__github__*`).
- **MCP SDK stability**: the `@modelcontextprotocol/sdk` is still evolving; breaking changes require updating the bridge. The version is pinned, and the SDK is widely adopted (Claude Desktop, Cursor, VS Code) so breaking changes are unlikely to be silent.
- **Tool schema quality**: MCP servers may expose poorly-described tools (vague descriptions, incomplete JSON schemas). The harness passes them through as-is — garbage-in-garbage-out; that is the server author's responsibility, not the bridge's.
- **Stdio process management**: a misbehaving MCP server that ignores signals could wedge dispose. The Cordis fiber disposal has bounded quiescence; a stuck transport eventually times out at the framework level.
- Crash recovery is manual (HMR edit or restart) — accepted for v1; a `reconnect` config remains open as future work.

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# RFC: The session prefix — request-only messages in front of the derived history
Status: implemented
## Problem
A plugin often owns a session-stable opener the model must always see — a skills catalog, an AGENTS.md digest, a workspace baseline. Before this seam the harness offered two homes, and both are wrong for that content. The system prompt is one rendered string: message-shaped content (a user-role `<system-reminder>` envelope, a multi-message primer) does not fit it, and providers weight conversation messages differently from system text. Durable history (`agent.inject()`, a `context/message` at session start) makes the opener permanent: every `deriveMessages()` consumer replays it, the compaction retention walk owns it, forks bake it in stale, and a resume cannot refresh it — a catalog captured at session birth outlives the world it described.
The obvious third option — let a plugin edit the request's `messages` on the way out — is banned by [the reconstructable-requests RFC](../architecture/2026-07-05-reconstructable-requests.md): every loop-built request is a pure function of the session log, so whatever channel carries the opener must log exactly what it sends. What was missing was a request-only message channel with a durable record.
## Decision
`agent/session-prefix` is a waterfall on the agent event map ([`packages/core/agent/src/types.ts`](../../../../packages/core/agent/src/types.ts)): listeners receive a frozen empty seed and return an extension (the canonical contribution is a prepend, `[mine, ...await next()]`, which yields registration order on the wire). The loop ([`packages/core/agent-loop/src/loop.ts`](../../../../packages/core/agent-loop/src/loop.ts)) fires it once per loop instance, lazily before the instance's first `agent/pre-step`; the composed list is deep-cloned, deep-frozen, cached on the instance, and placed in front of the ENTIRE derived history — directly after the provider's system slot — on every request the instance sends ([wire order](../../../core-data-structures/core.md#the-request-envelope-llmcallconfig-and-the-logged-header)).
Three properties carry the design:
- **Request-only, header-logged.** `deriveMessages()` never returns the prefix; its one durable record is `EpochHeader.messagePrefix` on the instance's anchoring `request/header` snapshot — the channel the reconstructable-requests RFC already owns for the request's non-history half, so no new session event exists. The dev invariant ([dsh-invariants](../../../../packages/support/invariants/src/index.ts)) recomputes `messagePrefix + boundary derivation` against every loop-built request; an unlogged prefix cannot reach the wire.
- **Frozen per instance.** Reuse is structural, not disciplined: the cached product cannot change mid-session, so the provider's prompt cache holds by construction and the prefix extends the cacheable region at zero marginal cost per step. A process restart or `ctx.agents.resume()` is a new instance: it recomposes, and any drift lands attributably on the `'resume'` header snapshot. This is the routing rule the seam creates: session-frozen openers ride the prefix; content that changes mid-session rides the append-only history channels (`agent.inject()` or tool/prompt-submit `additionalContexts` — [the interception-seams RFC](2026-06-30-interception-seams.md)), each a durable `context/message` paid once and prefix-cached thereafter.
- **Composed before the pressure gate.** Composition precedes the instance's first `agent/pre-step`, and the seam hands the composed value through: `agent/pre-step` carries a `sessionPrefix` parameter and `CompactService.compactIfNeeded(agent, fullSystemPrompt, sessionPrefix, signal)` counts it in its token-pressure estimate — a gate reading the previous instance's folded prefix instead would under-gate a resumed or forked instance whose contributor grew, skipping compaction and shipping an over-window first request. A composition interrupted by a cancel/dispose landing inside the waterfall is discarded, never cached: an abort-aware listener's degraded fallback cannot leak into later requests, and the next turn recomposes under a live signal.
Because composition runs before the boundary snapshot, a composing listener's session append joins the CURRENT request's derived history. Compaction structurally cannot touch the prefix (or the system prompt): it rewrites surface nodes, and header state never enters the surface.
## Testing
[Interception tests](../../../../packages/core/agent-loop/tests/interception.spec.ts) pin compose-once reuse with no header deltas, prepend order, empty-prefix omission, immutability, and composition before pre-step; [cancellation tests](../../../../packages/core/agent-loop/tests/cancel.spec.ts) pin discard and recomposition. Session codec, invariant, and compaction tests cover header round trips, request reconstruction, and prefix-aware pressure accounting. Snapshot normalization preserves prefix counts, while the [pinned-header scenario](../testing/2026-07-06-pin-request-header-content-in-one-scenario.md) owns content and the default example remains prefix-free. No prefix-specific e2e is needed because the seam is deterministic and provider-independent; the with-key [request-cache e2e](../../../../packages/core/agent-loop/tests/request-cache.e2e.ts) covers its cache economics.
## Alternatives considered
- **Per-request `before`/`after` slots recomputed every step** (the shape first proposed: a waterfall firing on every request, contributing frozen `before` messages ahead of the history and fresh `after` messages behind it) — rejected. A per-step `before` recompose invites silent drift — nothing anchors it to the log short of logging a header delta per step — and an `after` slot sits behind the growing history, so its tokens re-pay on every request and everything after it is uncacheable. Measured against the alternatives, every current update pattern is served cheaper by a durable append (paid once, cache-read thereafter), and the only content with no home was the session-stable opener — which wants freezing, not recomputation.
- **A system-prompt section** (`system-prompt/assemble`) — rejected for this content: the assembly renders to the single `system` string, so message-shaped openers do not fit, and the system prompt is deliberately re-assembled per step (with header deltas when it changes) while the opener wants instance-frozen semantics.
- **A durable history opener** (`inject()` at session start) — rejected: permanent history is the failure mode in the problem statement — replayed everywhere, compactable, stale across resumes.
- **Compose per turn instead of per instance** — rejected: a turn-boundary recompose either desyncs silently from the log or forces a header delta per change, and it busts the provider cache exactly as often as it fires; the legitimate refresh point is the instance boundary, where the `'resume'` snapshot already records drift attributably.
- **Compose lazily at the first request and let compaction read the folded header** (the shape as first merged) — superseded in review: the fold matches the live prefix only from the instance's second request on, so on a resumed/forked instance's first step the pressure gate read the PREVIOUS instance's prefix and could under-gate. Composing before the first pre-step and handing the live value through the seam makes the estimate exact at every step.
- **A dedicated session event carrying the prefix** — rejected: the header events are the request's non-history record by design; a second event would be a second home for the same fact and another codec to keep total.
## Consequences
- `agent/pre-step` and `CompactService.compactIfNeeded` carry a `sessionPrefix` parameter: every pre-step listener and compaction backend sees the real per-instance value (all in-repo implementations updated in the same change, per the pre-release stance).
- A contributor whose content changes mid-session is not re-read until the next instance — by design. A deployment needing mid-session catalog updates routes the change notice through the append-only history channels and pays one durable `context/message`.
- The dropped `after` slot leaves no request-only channel near the request tail; nothing in the repo needs one, and adding it back would re-open the every-step re-pay cost the design exists to avoid.
- The `request/header-delta` `messagePrefix` arm (whole-array replacement, empty array encoding transition to absence) exists for codec totality; the loop never exercises it, because the cached prefix cannot change within an instance.
- An empty composition is canonical absence: no-contributor deployments log no extra header bytes and their requests are the bare derivation.

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# RFC: Background subagent tasks
Status: implemented
## Problem
The [subagent seam](2026-06-21-subagent-capability-seam.md) returns a `SubagentRun`, but the model-facing tool originally collected every run synchronously. Independent, slow delegations therefore held the parent call open or ran serially.
Subagents need the same start, collect, list, stop, ownership, notification, and cleanup behavior as other long-running tools without adopting process-stream semantics. The child session remains the detailed trace; the parent needs the final answer and task status. A background child also outlives its starting tool call, so its cancellation and owner-disposal contracts must be explicit.
## Decision
Each `dsh-tool-subagent` instance may expose `run_in_background`, controlled by `enableRunInBackground` and enabled by default. A disabled instance omits the parameter and rejects a forced background argument at execution. Provider selection remains deployment configuration, so one instance still registers one distinctly named tool for one provider.
Background subagents use the [generic background task runtime](../architecture/2026-06-20-generic-long-running-tool-runtime.md). Collection, listing, cancellation, completion notices, and prompt guidance come from `task_output`, `task_list`, and `task_kill`; there are no subagent-specific companion tools.
Foreground calls retain their synchronous contract: await provider startup and `run.result`, return final text only for `completed`, map other terminal reasons to an errored tool result, and always dispose the run before returning.
For a background call, the tool validates the parent and refuses an already-aborted execution signal before calling `ctx.tasks.start()`. The task runtime preflights the control surface and owner cleanup before invoking the producer starter. That starter creates an independent `AbortController` and begins `ctx.subagents.start()`; after the id is returned, the tool-call signal no longer owns the child.
The task registration maps the subagent seam as follows:
- `kind` is `subagent`, `label` is the model-supplied description, and `owner` is the parent agent.
- `cancel(reason?)` aborts the task-owned controller. The same signal covers pending provider startup and the ready child.
- `done` awaits provider startup, the child result, and `run.dispose()`. Completed runs return final text, aborted runs become `killed`, and other stop reasons become `failed`. Startup, result, and disposal failures become failed outcomes rather than rejected task promises.
- `readOutput` is absent. While live, `task_output` returns status only; after settlement, it returns final output idempotently. Intermediate child activity remains in the child session.
## Lifecycle
A background subagent belongs to its parent agent and is not durable across owner closure. The task runtime attaches cleanup to the exact owner's scope. Agent disposal cancels the task and awaits startup rollback or child disposal before `AgentHandle.dispose()` resolves, preventing leaked child agents and sessions.
Completion notices target the exact owner captured at start. If owner teardown has already disposed the injection target, the notice is dropped; cleanup, not notification, is the lifecycle guarantee.
## Model guidance
The generic task prompt teaches the shared habit: retain ids, continue independent work instead of busy-polling, collect relevant tasks before answering, and kill irrelevant work. The subagent schema adds only that background mode returns a task id and that `task_output` collects the result. Authorization and owner cleanup enforce the runtime boundary independently of prompt compliance.
## Alternatives considered
### Subagent-specific wait, output, and stop tools
Capability-specific tools would duplicate the task protocol, teach another collect-and-stop habit, and complicate multiple provider instances. The generic runtime provides the required behavior without changing the tool's one-provider-per-instance shape.
### Survival after owner closure
Survival requires persistent task state, child-session recovery, a late-result delivery channel, and policy for abandoned owners. Owner-scoped cleanup gives process-local work a clear lifetime. Durable jobs require a separate design.
### No owner checks for isolated clients
Agents and logs may be session-scoped, but the task registry and predictable ids are runtime-global. The generic owner fence therefore applies to subagents like every other producer.
### Incremental child transcript output
Streaming child history into the parent would blur the log boundary and make provider behavior diverge. This surface exposes final output only; richer observation belongs to session or UI tooling.
## Testing
Unit coverage pins stop-reason mapping, dispose-before-report behavior, startup and result failures, pre-aborted refusal, detachment from the starting call's signal, cancellation before and after provider readiness, collection through the real task tools, the no-surface preflight fence, missing-runtime failure, and per-instance schema gating. Snapshot coverage pins the model-facing schemas.
## Consequences
The parent can fan out slow delegations and collect them through the same task controls used by bash. Child work no longer occupies the starting tool call, but it can consume resources until collected, killed, or owner-disposed. Prompt guidance encourages collection; owner cleanup provides the hard lifetime boundary. Deployments that require synchronous delegation can disable background mode per tool instance.

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# RFC: Repeat-tool-call guard plugin
Status: implemented
## Problem
A model stuck in a loop re-issues the same tool call with byte-identical arguments — re-running a failing grep, re-reading an unchanged file, polling a command that already gave its answer — and each round trip burns tokens, wall-clock, and (for paid APIs) money without adding information. The harness has nothing that notices: the loop has no step budget, no plugin tracks call repetition, and the model only escapes when it happens to vary its own behavior. The failure mode is real and cheap to detect — [pi-repeat-tool-guard](https://github.com/Kingwl/pi-repeat-tool-guard) ships exactly this as a pi coding-agent extension: count consecutive identical calls and, past a threshold, append a `<system-reminder>` telling the model to stop repeating itself and change course.
The harness already has every seam the pi extension uses, and better ones: [the interception-seams RFC](2026-06-30-interception-seams.md) gives `tools/post-execute` a sanctioned way to attach model-facing context to a finished call, the loop buffers and injects that context with call/result adjacency preserved, and injected context is a logged `context/message` — so a native guard satisfies the model-visible ⟺ logged rule with no new session event. What was missing was only the plugin itself.
## Decision
The guard is a loop-hygiene plugin, not a model-facing tool. It counts consecutive calls to the same tool with identical canonical arguments and injects advisory reminders at configured thresholds. It never delays, blocks, or rewrites a call; the model decides whether to retry differently or finish.
The plugin is `@deepseek-ai/dsh-repeat-tool-guard` at `packages/guard/repeat-tool-guard/`, opening the `guard/` group for loop-hygiene plugins (single-package groups have precedent: [the todo-write RFC](2026-06-29-todo-write-tool.md) shipped `todo/tool-todo`). It registers three listeners and holds all state in plugin-local maps keyed by `AgentId` — the tool registry is a context-level singleton whose waterfalls interleave every agent's calls (subagents run on the same context), so per-agent keying is correctness, not polish.
- **`tools/post-execute` (waterfall)** — the one detection point. The listener receives `(exec, result)` together, so counting and reminder delivery need no cross-event pending map (the pi extension needs one only because its `tool_call`/`tool_result` hooks are separate events). It always delegates via `next()` and, when a threshold is hit, prepends a reminder to the downstream decision's `additionalContexts` — the observe-and-enrich posture [the hooks bridges](2026-06-30-hook-bridges.md) already use, honoring the waterfall contract. Counting happens here rather than in `tools/pre-execute` because post-execute also runs for denied calls (`ToolRegistry.execute` routes a deny through the same pipeline), and a model hammering a denied call is exactly the loop worth breaking.
- **`agent/prompt-submit` (waterfall)** — pure reset hook: delegate via `next()`, clear the submitting agent's chain. A user interjection changes the context; repetition across it is not a loop.
- **`agent/status` (emit)** — on `disposed`, drop the agent's state, bounding the maps over harness lifetime.
### Detection semantics
The chain key is `(tool name, canonical arguments)`; a call identical to the previous tracked call increments the agent's consecutive counter, a different tracked call resets it to 1. Canonicalization is a deep key-sort plus `JSON.stringify`: `ToolExecution.arguments` is by construction the loop's `JSON.parse` output (or the raw string fallback for malformed argument JSON, which is itself a comparable value), so the pi original's bigint/circular/`undefined` handling has no inputs here and is deliberately dropped.
Two deliberate rules, both documented in [the package README](../../../../packages/guard/repeat-tool-guard/README.md) because they are behavior a reader would otherwise guess at:
- **Untracked calls are transparent to the chain.** A call excluded by `include`/`exclude` neither increments nor resets the counter, so `grep X → todo_write → grep X` still counts as two consecutive `grep X` when `todo_write` is excluded. This is what makes exclusion useful — bookkeeping tools interleaved into a loop must not launder it — and it is the pi extension's (undocumented) semantics, kept on purpose and written down.
- **Calls without an agent are ignored.** A direct `ctx.tools.execute()` caller (tests, non-loop consumers) has no model to remind and no `AgentId` to key on.
### Reminder delivery
Reminders ride `additionalContexts` as their own entries (source `{kind: 'plugin', plugin: 'repeat-tool-guard'}` — the label is load-bearing per `HookContext`), never a `content` replacement: the `tool/result` event stays the tool's own output for audit, and the loop appends buffered contexts as `context/message`s after the step's results, which the session renders as tagged synthetic-user envelopes and derived history replays. Thresholds escalate: the first configured threshold gets a short "you are repeating yourself, analyze the previous result" nudge; each later threshold gets the detailed form naming the tool, the repeat count, and the canonical arguments (head-truncated at `argumentsPreviewChars`, default 500 — a looping `write`-sized payload must not ride into the next request unbounded; the chain key always compares the full canonical string), and stating that the calls made no progress. The pi original hardcodes the gentle text to the literal count 3; the guard keys it to `thresholds[0]`, fixing that bug in the port. A downstream hook bridge contribution remains a separate array entry, so both plugins retain their source, envelope, and metadata.
### Config
```yaml
- id: repeat-tool-guard
name: '@deepseek-ai/dsh-repeat-tool-guard'
config:
thresholds: [3, 5, 8] # default; consecutive counts that trigger a reminder
include: [] # tool-name patterns to track; empty ⇒ all tools
exclude: [todo_write] # tool-name patterns transparent to the chain
argumentsPreviewChars: 500 # default; cap on arguments quoted in the detailed reminder
```
`thresholds` is validated at load and throws on an empty list, a non-integer, a value below 2, or a duplicate — misconfiguration fails loud, replacing the pi original's silent fall-back to defaults. `include`/`exclude` entries support `*` wildcards. Patterns are predicates over whatever tools exist at call time, not references to a registry entry, so an entry matching no currently registered tool is NOT an error — unlike `toolOrder`'s referent check, `exclude: [mcp_*]` must stay valid in a deployment that loads no MCP tools.
## Testing
- **Unit:** A real loop with a scripted adapter covers counting and reset rules, untracked transparency, disposal cleanup, per-agent isolation, canonical argument key order, escalation, denied calls, no-agent execution, wildcard escaping, invalid config, and downstream block or replacement decisions at per-file 100% coverage.
- **Snapshot:** The keyless `repeat-tool-guard` scenario makes five identical `todo_write` calls and pins the gentle third-call and detailed fifth-call reminders in both ACP output and the session log. The plugin is loaded in the live example but remains inert in other scenarios.
- **E2e:** None; the plugin is deterministic and provider-independent, and its seam contracts are covered by their owners.
## Alternatives considered
- **Append the reminder into the tool result** (`accept` with replaced `content` — the pi extension's mechanism, which patches result content because that is the only channel its API offers) — rejected: it makes the logged `tool/result` lie about what the tool returned, and `additionalContexts` is the separate sanctioned channel for post-execute commentary, with loop-level buffering that preserves call/result adjacency.
- **Count in `tools/pre-execute` with a pending-reminder map** (the pi two-phase shape) — rejected: post-execute alone sees `(exec, result)` together and also fires for denied calls, so one listener with no cross-event state covers strictly more attempts with less machinery.
- **Escalate to `block` at the highest threshold** — rejected for the initial scope: a blocked call punishes legitimate identical repeats (polling a long-running terminal, re-checking a file the agent expects to change), and an advisory reminder keeps the model in control. Revisit with evidence; the decision shape (`PostToolDecision`) already supports it.
- **A per-deployment external hook via the CC/Codex bridges** (a `PostToolUse` script) — rejected as the answer: it works for one deployment, but a shipped, unit-tested, `cordis.yml`-configurable plugin is the harness-native form, without per-call subprocess cost.
- **A loop-level step or repetition budget in `agent-loop`** — rejected: "plugins, not loop changes"; a hard step budget is a blunter, orthogonal control that would need its own proposal.
- **Fuzzy/near-identical detection** (normalized paths, similar-but-not-equal arguments) — rejected: exact match after canonicalization is cheap, deterministic, and explainable to the model; similarity thresholds invite false positives and need evidence before they earn complexity.
- **Placing the package in `core/`** — rejected: core is the product spine; a behavioral guard is an optional leaf plugin, and the `todo/` precedent is a small dedicated group per plugin family.
## Consequences
- The reminder is advisory by design: idempotent polling patterns that repeat identical calls on purpose still receive nudges past the thresholds, and the pressure valves are config (`thresholds`, `exclude`) plus reminder text that explicitly allows finishing when enough evidence has been gathered. Each trigger costs reminder tokens on the next request; thresholds bound the frequency.
- Chain state is in-memory only: a session resumed from persistence starts with a fresh chain, so a loop spanning a resume draws its reminders later than a live one — accepted, the guard is a heuristic nudge, not a logged invariant, and persisting counter state would buy little for real complexity.
- When multiple post-execute producers attach context on one call, each contribution stays a separate `HookContext`; ordering follows waterfall nesting and each entry retains its own provenance.
- Implementing the snapshot tier surfaced a hidden assumption in the suite kit: the fixture guard equated "authored model scenario" with "override-driven". The `Scenario` table now carries an explicit `overridden` flag, and the sidecar's presence is checked BOTH ways against it (an unregistered stray sidecar would silently replace the derived script) — the suite kit is stricter than it was before this plugin existed.
## Deferred
- Compaction does not reset chains: a compacted history changes what the model sees, but the repetition risk usually survives compaction.
- Escalating to `block` at a high threshold is not implemented; `PostToolDecision` already supports it if evidence arrives.
- Subagent chains stay isolated per agent; no sharing mechanism exists until a concrete case appears.

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# RFC: The self-referential cordis toolset
Status: implemented
## Problem
Everything in this harness is a cordis plugin, but the agent running inside that plugin runtime cannot see or touch it: it cannot enumerate the services and events around it, cannot extend itself with a new tool mid-session, and cannot compose capabilities it invents. Handing the model that power is worth exploring — a self-referential agent that inspects and modifies its own runtime — but it raises three correctness problems at once, and the design is about answering them rather than the raw "let the model run code" mechanic.
First, model-written registration must be validated where it happens: a malformed tool schema has to fail at registration, not when a later request tries to assemble it into a prompt. Second, model-written code has to call service APIs whose source it has never seen — guessed method signatures and, worse, guessed return-value shapes cost many steps of blind probing. Third, everything the model mounts must be fully disposable, by the model on demand and by the ordinary plugin lifecycle when the host plugin reloads, or a long session accretes orphaned listeners and tools.
## Decision
The toolset ships as [`@deepseek-ai/dsh-tool-cordis`](../../../../packages/cordis/tool-cordis/README.md) — a new top-level `packages/cordis/` group — and is demoed by [`examples/cordis-agent`](../../../../examples/cordis-agent/README.md). It gives the model three tools over the live cordis runtime it is running inside: inspect it, mount model-written plugins into it, dispose them again.
The vm isolates accidental global pollution, and the context façade hides framework internals. Neither restricts the authority of exposed services: a mount can call `ctx.bash` to run commands with the host executor's privileges and can reach the real filesystem and web services. This is an opt-in development tool with bash-equivalent trust, not a security boundary or product default.
### The three tools
| Tool | Contract |
|---|---|
| `cordis_inspect` | Read-only report over the live runtime, one Markdown section per `what` value (omit `what` for all sections). Never mutates. |
| `cordis_mount` | Evaluates `code` (the body of an async JavaScript function) in a `node:vm` sandbox; the code must `return` a cordis plugin, which is mounted as a child of the `cordis-dynamic` group fiber and tracked under a fresh id (`dyn-1`, `dyn-2`, …). |
| `cordis_unmount` | Disposes one dynamic mount by id and returns only after disposal reaches quiescence — every registration the plugin made is unwound, not merely requested to stop. |
`cordis_inspect` sections: `services` (every provided ctx service and the owning fiber, non-active owners flagged), `plugins` (a flat list of every loaded plugin with its lifecycle state, from `ctx.registry` — what capabilities are loaded, deliberately not the tree shape), `tools` (what the model can call), `dynamic` (the mount table: id, name, state, provided services, awaited services), `api` (live service signatures + the type shapes they reference, from the generated catalog), and `events` (harness events with dispatch mode and signature). The model-facing tool descriptions carry the operational rules the model needs at call time; [the generated tool catalog](../../../tool-catalog.md) is their exhaustive rendering.
### Sandbox semantics
Mount code runs as an async-function body in a fresh vm realm. Its documented surface steers file, network, process, and timer access through Cordis services so mounts remain inspectable and disposable. Host-realm helpers still make Node escape possible, consistent with the trusted posture. `vmTimeoutMs` bounds only synchronous evaluation.
Sandbox globals are deliberately small: a tagged write-through `console` (`[cordis:<id>] …` on the host stdout/stderr, so a listener that fires long after the mount call still lands somewhere the user sees), the `harness.defineTool` / `harness.registerTool` registration pair, the encoding primitives fresh vm contexts lack (`btoa`/`atob` as host closures over `Buffer` — a sanctioned exception, `Buffer` itself is never exposed — plus `TextEncoder`/`TextDecoder`), and callable traps over the withheld Node APIs (`require`, `setTimeout`/`setInterval`/`setImmediate`/`clearTimeout`/`clearInterval`, `fetch`) that throw a redirect naming the cordis alternative. Only function-shaped globals are trapped; `process` and `Buffer` stay `undefined` so a `typeof` feature probe stays inert rather than detonating a throwing accessor.
Mount code crosses the vm boundary through three controls. Dual-realm `instanceof` recognizes both host and vm objects. `harness.defineTool` normalizes results into host-realm JSON and validates the `ToolExecuteReturn` shape before logging. The mounted plugin receives a whitelist context façade, not a raw or pass-through `Context`; framework plumbing and context-valued returns are rejected. Service reads require a declared `inject`, preserving Cordis activation and unload semantics. `ctx.tools.get` exposes only the schema view, so mounted code cannot bypass `ToolRegistry.execute` by calling a definition directly.
The boundary normalizes unambiguous JSON-Schema forms into `SchemaSpec`, including object wrappers, `integer`, and optional fields. Invalid vocabulary fails with the accepted alternatives. Parse, TypeScript, missing-return, Node-API, and duplicate-tool errors include the relevant source line or corrective contract without narrating implementation internals.
### The dynamic group and mount lifecycle
All dynamic mounts are children of one `cordis-dynamic` group beneath the tool plugin, so ordinary fiber disposal handles reload and unload. Mounting awaits settlement; startup failure disposes the fiber before returning an error. A settled pending mount remains visible with its missing injections. `cordis_unmount` awaits the mount fiber's disposal.
### Cross-mount composition via provide/inject
Mounts relate to each other through ordinary cordis service semantics, with their ids as the lifecycle handles: mount A calls `ctx.provide('foo', value)`, mount B declares `inject: ['foo']` and activates the moment `foo` exists; mounted first, B stays pending and names the missing service; unmounting A sends B back to pending (its registrations unwound) and a later re-provide re-runs B's `apply` through a fresh sandbox façade; a duplicate provide fails loud with the owning fiber named. One realm caveat: a service value provided by a mount is a vm-realm object — method calls on it work from anywhere, but consumers must not assume host prototypes on it.
### The generated API catalog
`cordis_inspect` serves API and event data from a generated catalog rather than a duplicated table. The generator reuses the Cordis catalog AST scan and emits service summaries, signatures, event modes, referenced type declarations, and the inherited context surface. Ambiguous type names are omitted and oversized declarations are marked as truncated.
Freshness is gated like every generated artifact: `pnpm run verify-cordis-api` (in `doc-sync`) regenerates in memory and fails on any diff, so a JSDoc edit that changes a public signature cannot ship without regenerating the catalog the model reads. At runtime the inspect tool intersects the catalog with the live runtime rather than dumping it: live catalogued services render summary + signatures, live services without a catalog entry (mount-provided ones) render name + owning fiber, catalogued services with no live provider are listed tersely, and the referenced type shapes follow.
### Configuration, rendering, and observability
The plugin exposes one config field, validated by schemastery and documented in [the config catalog](../../../config-catalog.md): `vmTimeoutMs` (default 5000), the millisecond bound on the synchronous portion of mount-code evaluation. Tool names, the `cordis-dynamic` group name, and the `dyn-` id prefix are structural vocabulary and stay fixed. All three tools render as `generic` cards per [the tool cookbook](../../../cookbook/adding-a-tool.md) (`cordis_inspect` a `read`, `cordis_mount` an `execute` carrying the code as `rawInput`, `cordis_unmount` a `delete`), with no `presentResult` overrides.
Model-visible ⟺ logged holds with no new session event type: a mount or unmount is visible only through its own `tool/call` / `tool/result` pair, which the loop logs, and the changed tool set a mount induces is logged by the request-header delta the loop already emits when schemas change between steps. There is deliberately no `cordis/mount` provenance event — it would duplicate what the tool-call pair records. Dynamic mounts are process-lifetime, not session state: resuming a persisted session rehydrates the conversation but does not re-mount plugins.
## Alternatives considered
**A structured per-capability registration tool instead of `cordis_mount`.** The most tempting alternative is a `cordis_register_tool` with explicit `name` / `description` / `parameters` / `code` fields (and siblings `cordis_register_listener`, `cordis_register_service`, …) rather than a single "mount a plugin" primitive. It was rejected because its one real win — no plugin boilerplate for the single commonest case — does not pay for its costs, while a single mount primitive answers every capability at once.
| Dimension | Structured per-capability tools | Single `cordis_mount` |
|---|---|---|
| Schema correctness | `parameters` is still a model-written JSON object needing SchemaSpec validation, merely one step earlier | The same validation runs at the sandbox boundary, with the same instructive errors |
| The code field | An `execute` body is still model-written JS in a vm; the realm and service-call correctness problems are unchanged | One sandbox, one normalization path, one guarded registration |
| Capability coverage | Tools only; listeners, services, `inject` relations each need another structured tool — a surface that grows without bound | One vocabulary (a cordis plugin) covers every effect, present and future |
| Cross-mount composition | Not expressible in a tool-registration payload | Native `provide`/`inject`, ordinary cordis semantics |
| Inspectability | Registers something the plugin list cannot show as a plugin | What the model mounts is exactly what `cordis_inspect` renders |
| Model ergonomics | Wins for the single most common case (no plugin boilerplate) | Mitigated by the canonical recipe in the mount description plus boundary errors that teach the fix |
The correctness investment therefore goes where it pays for every capability at once: the generated API catalog surfaced through `cordis_inspect`, and sandbox-boundary validation whose error messages teach the correct call. A structured registration tool remains addable later as sugar that synthesizes mount code; nothing here forecloses it.
**A hand-maintained service/event reference in the tool.** The first cut of the inspect tool carried a hand-written table of service method signatures. It was replaced by the generated `api-catalog.ts` because a hand table drifts from the JSDoc the moment a signature changes and nothing gates the drift, whereas the generated artifact is freshness-checked against the same AST the docs use.
**A new `cordis/mount` session event.** A durable provenance event recording each mount (source, name) has clear precedent (`hook/invoked`, `compact/start`). It was declined for v1: mount and unmount are already visible as `tool/call` / `tool/result` pairs and the tool-set change is already logged as a request-header delta, so a dedicated event would only duplicate the record. It remains addable if an audit use case needs mount provenance separable from the tool call.
**A hardened / capability-restricted sandbox.** Trapping Node built-ins and handing mount code a whitelist façade rather than the raw context might suggest an intent to sandbox for safety. It is explicitly not that: the traps and the façade narrow the *surface* mount code sees — steering it onto cordis services and away from leak-prone Node built-ins and framework internals — for correctness and to close the unguarded-context escape, but the capabilities the façade exposes (`ctx.bash`, `ctx.fs`, `ctx.web`) reach the real runtime, so it is not a security boundary. A real one (separate process, permission prompts) was out of scope for a dev/opt-in toolset and would fight the entire point — handing the model the live runtime.
## Consequences
The toolset is a deliberate opt-in with a fully-privileged `ctx`, so a deployment adopts it as consciously as a bash tool. Several facts follow that the tool descriptions warn the model about directly: a waterfall listener (e.g. `tools/pre-execute`) that returns without calling `next()` vetoes the chain, so a mounted listener can lobotomize the agent's own tool dispatch ([waterfall semantics](../../../cordis-primer.md#cordis-waterfall-semantics)); mount code runs inside a tool call of the current turn, so awaiting anything that resolves only after the turn deadlocks; `vmTimeoutMs` bounds synchronous evaluation only; and mounts do not survive session resume.

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# RFC: Bash-backed grep and glob discovery tools
Status: implemented
## Problem
The harness needs model-facing `glob` and `grep` tools, but making them `ctx.fs` provider methods turns a local product convenience into a universal filesystem backend contract. Local workspace discovery is naturally a process-backed `rg` workflow; remote or virtual filesystem backends may expose their own search API, may not share a local `ripgrep` view, or may not support discovery at all. The v1 should not require every filesystem backend to implement search before the file read/write/edit seam has proven that need.
Search output also has two distinct budgets. The tool needs enough raw `rg` output to compute a stable logical result, but the model should receive only a bounded preview plus a recovery path when the formatted result is larger than the inline budget. The generic spill policy only sees the final tool result, so it cannot recover matches that a search tool already omitted. Search therefore needs tool-owned retention and best-effort formatted-result spill.
## Decision
`glob` and `grep` are model-facing tools in `@deepseek-ai/dsh-tool-fs-search`, backed by the bash seam, not by new `ctx.fs` provider methods. The package registers model-facing filesystem discovery tools, but execution uses `ctx.bash.resolve(request)` followed by `ctx.bash.run(spec)` with fixed `rg` command templates assembled by the tool. The tool layer owns schemas, argument validation, shell quoting, result parsing, result formatting, retention, formatted-result spill handoff, and timeout declaration. The bash executor owns request defaulting/capping, subprocess execution, process-group termination, environment scrubbing, raw output capture, and backend substitution across local, sandboxed, or remote bash implementations.
The tools do not use `ctx.bash.start()` and do not create model-visible background tasks. They run as ordinary foreground tools from the agent loop's perspective: the tool call returns only after the `rg` command exits, times out, is aborted, or fails. `defineTool({ timeoutMs })` declares the cooperative tool-call budget, `@deepseek-ai/dsh-timeout-policy` enforces it through `exec.signal`, and the tool forwards that signal into the bash request before `resolve()` / `run()`. The bash backend's own timeout remains a second safety cap; whichever aborts first wins.
The tools align `path` with Claude Code's search tools while binding resolution to the bash workdir, not to `ctx.fs`. The tool derives the bash request workdir from `exec.agent?.session.header.cwd`, mirroring `dsh-tool-bash` and `dsh-tool-fs`; when no session cwd exists, it omits `request.workdir` so the bash implementation applies its configured cwd or process cwd through `resolve()`. For `grep`, `path` is an optional ripgrep target and may be a file or directory; omitted means the resolved bash workdir. For `glob`, `path` is an optional directory search root; omitted means the resolved bash workdir. Relative `path` values resolve against that workdir. Returned paths are displayed relative to the resolved bash workdir when possible and are intended to be follow-up-readable only in co-located deployments where the bash workdir and filesystem `read` root are the same workspace. v1 documents that deployment requirement but does not perform runtime cross-service validation. Remote or virtual filesystem search is deferred until there is a shared workspace/root contract or a provider-specific search backend.
The package does not inject `fs`. It injects `tools`, `systemPrompt`, and `bash`; it deliberately reads `spillStore` with `ctx.get('spillStore')` instead of static inject because formatted-result spill is optional. Existing `@deepseek-ai/dsh-tool-fs` deployments that only want `read` / `write` / `edit` do not need to load bash.
### Package shape
The v1 package stays small. Inside `@deepseek-ai/dsh-tool-fs-search`, the source layout is:
```text
src/index.ts
src/glob.ts
src/grep.ts
src/search-core.ts
src/shell-quote.ts
```
`glob.ts` and `grep.ts` own their parameter validation, command construction, result parsing, formatting, and registration. `shell-quote.ts` is one shared helper because shell quoting is the safety boundary both tools must use; `search-core.ts` is the other (an implementation-time amendment to the original four-file plan): the `SEARCH_*` error vocabulary, the bash-run + raw-output acquisition, the formatted-spill handoff, and workdir-relative display are byte-identical between the two tools, and duplicating that delicate plumbing per tool is exactly the missed extraction the symmetry convention flags. Command builders must not hand-roll quoting or concatenate unquoted model-controlled values into the shell command.
### Schemas and config
`glob` exposes the small discovery shape:
```ts
interface GlobArgs {
pattern: string
path?: string
}
```
`grep` exposes the OpenCode-style minimal shape:
```ts
interface GrepArgs {
pattern: string
path?: string
include?: string
}
```
Routine budgets stay out of the model-facing schema. `@deepseek-ai/dsh-tool-fs-search` owns these defaulted, validated config fields:
| Field | Default | Role |
|---|---:|---|
| `globMaxResults` | `100` | Max paths retained inline; matches Claude Code's default `GlobTool` result limit. |
| `grepMaxMatches` | `250` | Max flat matches retained inline; matches Claude Code's default `GrepTool` `head_limit`. |
| `grepMaxLineBytes` | `2000` | Max bytes retained for one matched-line preview, applied with `TextRetainer({ kind: 'head', maxBytes: grepMaxLineBytes })`. |
| `rawOutputMaxBytes` | `20000000` | Max complete raw `rg` stdout the tool will parse; matches Claude Code's ripgrep raw buffer. |
| `timeoutMs` | `30000` | Tool-call timeout attached to both tool definitions and enforced by `@deepseek-ai/dsh-timeout-policy`. |
`globMaxResults` and `grepMaxMatches` use `ItemRetainer({ kind: 'head' })`. `grepMaxLineBytes` uses `TextRetainer({ kind: 'head', maxBytes: grepMaxLineBytes })` for each matched line so preview cuts preserve UTF-8 boundaries. This follows the [tool result retention library](../../implemented/architecture/2026-07-06-tool-result-retention-library.md) mapping for discovery items: collect the complete result, retain head items inline, and keep path mapping, grouping, and per-line preview outside the retainer. `grep` does not expose `case_insensitive`, `head_limit`, `offset`, `count`, multiline, context lines, output modes, or file type filters in v1. A model that needs surrounding context reads the matched file with `read`; a model that needs later results follows the returned spill locator's retrieval hint.
The Claude Code values are reference points for the two-layer budget, not model-facing schema precedent. Its dedicated search tools buffer raw ripgrep output up to 20 MB for internal processing, use a 20-second ripgrep timeout on non-WSL platforms (60 seconds on WSL), then apply search-specific caps before the model sees a result: `GrepTool` defaults to `head_limit = 250` and persists formatted results above 20,000 characters, while `GlobTool` defaults to 100 paths and persists formatted results above 100,000 characters. This RFC mirrors the raw-buffer and inline-count defaults, chooses a 30-second default search timeout, and uses this harness's `ctx.spillStore.saveText()` path for formatted-result recovery.
The `path` field follows the same split as Claude Code: `grep.path` is a file-or-directory ripgrep target, while `glob.path` is a directory search root. v1 does not expose a separate cwd/workdir argument on these tools.
`include` is one positive glob filter, not a list and not an exclude syntax. Reject comma-separated or negated include patterns up front with a structured argument error. Every model-controlled value used in a shell command, including `pattern`, `path`, and `include`, must pass through the package-private shell quoting helper.
### Execution
`glob` builds a fixed `rg --files` command rooted at the resolved directory search root (`path` when supplied, else the bash workdir): `rg --files --glob <pattern> --sort=modified --no-ignore --hidden`, plus VCS metadata excludes for `.git`, `.svn`, `.hg`, `.bzr`, `.jj`, and `.sl`. This aligns with Claude Code on hidden/ignored-file discovery and modified-time ordering while keeping VCS internals out of broad searches. The tool parses one path per line, maps results back to paths relative to the bash workdir when possible, pushes each path into `ItemRetainer({ kind: 'head', maxItems: globMaxResults })`, and formats the full sorted path list for a spill artifact when the retained result is capped.
`grep` builds a fixed line-oriented `rg --json` command against the supplied file/directory target (`path` when supplied, else the bash workdir) so file path, line number, and line text are parsed without colon-splitting ambiguity. It consumes `match` records, treats malformed JSON or malformed match records as `SEARCH_FAILED`, maps result paths relative to the bash workdir when possible, applies per-line preview retention with `grepMaxLineBytes`, pushes each match into `ItemRetainer({ kind: 'head', maxItems: grepMaxMatches })`, then groups only the retained preview matches by file for inline output. The spill artifact stores the full formatted match list, not only the omitted tail, so the retrieval hint points at the same logical result the model saw.
Raw `rg` stdout is an internal transport detail. The tool requests `stdoutMaxBytes: rawOutputMaxBytes` through `ctx.bash.resolve()` and parses `stdout.text` only when the executor returns untruncated stdout within that cap. If stdout is larger than `rawOutputMaxBytes`, or the executor still returns `stdout.truncated`, the tool fails with a clear search error telling the model to narrow `pattern`, `path`, or `include`. The tool never exposes raw `rg` output or bash raw spill paths to the model.
Only stdout is a parse source. Stderr is diagnostic text for invalid patterns, missing `rg`, and search failures; if bash truncates stderr, the tool uses the retained stderr tail with a truncation note and does not read `stderr.spillPath`.
If `ctx.bash.run()` reports `aborted` because the tool timeout or caller cancellation fired, the tool returns a structured failure rather than pretending there were no matches. If bash reports its own timeout first, the tool likewise fails with a clear timeout message. Nonzero ripgrep exit semantics are tool-owned: exit 0 is success with matches, exit 1 is success with no matches, invalid pattern / missing `rg` / inaccessible search workdir are failures.
Search failures use a package-owned `HarnessError` subclass with `SEARCH_*` codes, not `FsErrorCode`, because these tools are not `ctx.fs` provider operations. The v1 vocabulary is `SEARCH_INVALID_PATTERN`, `SEARCH_FAILED`, `SEARCH_RAW_OUTPUT_OVERFLOW`, and `SEARCH_ABORTED`. Model argument validation failures such as missing required fields, blank strings, or unsupported negated/list `include` values remain ordinary tool argument errors.
### Formatted result spill
`ctx.spillStore` is optional and used only for model-facing formatted results. This is the first tool-owned spill call pattern in the codebase, and it is intentional because search retention is item-level policy: `globMaxResults` caps paths and `grepMaxMatches` caps matches while the tool still holds the complete logical result. The generic `dsh-spill-policy` caps final text bytes on `tools/post-execute`; by then a search tool would already have omitted later paths or matches, so the policy cannot recover them.
When a search produces more logical results than the inline cap and `ctx.spillStore` is present, the tool saves the complete formatted result with `saveText()`. The spill owner is the calling agent's session header id (`exec.agent?.session.header.id`); without that owner, the search keeps the inline result and reports that the complete result could not be saved. The spill source is the tool execution identity: `{ toolName: exec.name, callId: exec.callId, label: 'result' }`. The suggested filenames are `grep-results.txt` and `glob-results.txt`; the spill backend still treats them as hints, never paths.
When spill storage is absent, the call has no session owner, or saving fails, the tool still returns the inline page and a footer explaining that the complete result could not be saved. Search success must not turn into an `isError` result solely because formatted-result spill storage is unavailable.
The bash raw output stream and the formatted search spill artifact are different artifacts. Raw `rg` stdout is parsed only in memory within the requested bash stdout cap; the formatted spill artifact is the stable model-facing recovery locator produced by `ctx.spillStore.saveText()`.
### Result shape
A capped `glob` result with successful formatted spill returns the inline page and a spill notice:
```text
<first N paths>
(Showing N of M paths. Full sorted result stored at: /.../session-abc123/9f8e7d-glob-results.txt. Use read with offset/limit, or grep this path to search within it.)
```
A capped `grep` result with successful formatted spill returns grouped preview matches and a spill notice:
```text
Found N of M matches
<file>
Line 12: ...
(Full grep result stored at: /.../session-abc123/9f8e7d-grep-results.txt. Use read with offset/limit, or grep this path to search within it.)
```
If the complete logical result fits under the inline cap, no formatted spill artifact is created. If the complete logical result is too large but formatted spill is unavailable, the footer says that the result was capped and the complete result could not be saved. The `truncated` / omitted count is a budget fact, not an incomplete-search fact; timeout, invalid regex, missing `rg`, inaccessible workdirs, raw-output overflow, binary skips, and parse failures stay in tool-domain error or incomplete fields.
## Alternatives considered
**Put `glob` / `grep` on `ctx.fs`.** Rejected for v1: it forces every filesystem backend to grow a search API and makes local ripgrep behavior part of the provider seam. Search is useful product behavior, but it is not a universal text-storage primitive like `readText` or `writeText`.
**Directly spawn ripgrep from `dsh-fs-local`.** Rejected for this RFC's v1: direct spawn gives the cleanest argv boundary, stdout/stderr control, and early-stop control, but it duplicates process execution concerns that the bash seam already owns: environment scrubbing, process-group kill, timeout propagation, sandbox/remote executor substitution, and bounded output capture. It remains a reasonable optimization if bash-backed search proves too shell-string-sensitive or if foreground streaming becomes necessary.
**Use `ctx.bash.start()` for streaming early stop.** Rejected: `start()` creates model-visible background task semantics: task ids, owner tokens, `bash_output`, `bash_kill`, completion notifications, and no built-in timeout. `grep` needs a foreground tool result, not a background bash workflow. If streaming search becomes necessary, the right abstraction is a foreground streaming process handle on the bash/process seam, not borrowing the public background-task API.
**Expose bash raw spill paths to the model.** Rejected: a bash raw spill path contains raw `rg` stdout (`rg --json` records for grep), not the stable formatted search result. Search parses raw stdout only as an internal transport; model recovery uses a formatted result saved through `ctx.spillStore.saveText()`.
**Add `spillStore.saveFile()` for bash output normalization first.** Rejected for this RFC's v1: `saveFile()` would help a future bash normalization pass move existing executor spill files into session-scoped spill storage, but search only needs bounded in-memory raw `rg` stdout before producing the model-facing artifact. `saveText()` is sufficient for the formatted search result.
**Rely on the generic `dsh-spill-policy`.** Rejected: generic post-execute spill sees only the final tool result. If `grep` / `glob` return the first page inline, the generic policy cannot recover omitted results. The search tools must save the complete formatted result themselves before returning the bounded model-facing text.
**Expose Claude Code's full `GrepTool` schema.** Rejected for v1: `output_mode`, context flags, multiline, `head_limit`, `offset`, `case_insensitive`, and type filters make the model-facing surface into a ripgrep wrapper. This harness keeps routine budgets and continuation mechanics in deployment policy and spill artifacts.
**Keep early-stop search and skip formatted spill artifacts.** Rejected for this proposal: early stop is more efficient but gives the model no path to inspect later results. The chosen v1 optimizes result recoverability and implementation simplicity, with `timeoutMs`, `rawOutputMaxBytes`, bash backend caps, and formatted spill artifacts as safety backstops.
**Expand the bash seam with a raw-output reader first.** Rejected: a portable `readRawOutput(ref, maxBytes)` API would add reference lifetime, permission, and backend storage semantics. A per-run `stdoutMaxBytes` request is the narrower seam: search either receives complete stdout within `rawOutputMaxBytes` or fails clearly.
## Testing
- Tests prove an aborted `exec.signal` reaches the bash backend (same-reference spec assertion plus the `SEARCH_ABORTED` result), and cover command construction/quoting (malicious patterns, paths with spaces, leading-dash values, quotes, newlines, glob metacharacters — unit assertions plus a real `bash -c` round-trip for every hostile value), `grep.path` as file and directory targets, `glob.path` as a directory search root, invalid pattern handling, no matches, malformed `rg --json` output, matched-line preview truncation, raw-output overflow, timeout/abort, formatted spill success/failure, the package-owned `SEARCH_*` error codes, and the no-background-task invariant.
- The first-party tool-owned spill precedent is covered directly: spill backend present, spill backend absent, `saveText()` failure, and missing spill owner.
- The package has real Loader-path coverage for the namespace plugin export shape (`name`, `inject`, `Config`, and `apply`, with no default export).
- A real-executor integration suite (`dsh-bash-local` + a real `rg`) verifies the world: hostile patterns stay inert, per-session cwd resolution, VCS-metadata exclusion, modification-time ordering, and real ripgrep stderr classification. It self-skips where `rg` is not on PATH (a CI accommodation mirroring the keyless e2e skip); the fake-executor suite alone carries the per-file 100% coverage gate.
- Snapshot gap note for the transcript-visible spill notice: this landed with the gap note, not a snapshot. The snapshot tier replays the acp-agent tree, and adding the search plugin there changes the assembled system prompt — every golden would need re-recording with a real key, which the implementing environment did not hold. The spill notice's exact transcript text is pinned by unit tests (`formatGlobOutput`/`formatGrepOutput` and the through-the-registry spill tests); wiring the plugin into the acp-agent tree plus a `test:snapshot:record` pass is the follow-up for the next key-holding session.
## Consequences
- `glob` and `grep` are model-facing tools in `@deepseek-ai/dsh-tool-fs-search`, not `ctx.fs` provider methods and not part of the existing `@deepseek-ai/dsh-tool-fs` root plugin. The package injects `tools`, `systemPrompt`, and `bash`; it does not inject `fs`, and `ctx.spillStore` stays optional via `ctx.get('spillStore')`.
- The schemas are exactly `glob(pattern, path?)` and `grep(pattern, path?, include?)`; search caps and timeout are defaulted, validated Config fields (`globMaxResults`, `grepMaxMatches`, `grepMaxLineBytes`, `rawOutputMaxBytes`, `timeoutMs`).
- The tools execute through `ctx.bash.resolve(request)``ctx.bash.run(spec)`, forward `exec.signal`, never call `ctx.bash.start()`, and never expose a bash task id. The bash request workdir comes from `exec.agent?.session.header.cwd` when available; the resolved `spec.workdir` drives execution and relative-path display.
- The tools request `stdoutMaxBytes: rawOutputMaxBytes` from the bash seam, parse only untruncated stdout within that cap, and treat over-cap or still-truncated raw output as a clear search failure; raw `rg` output is never exposed to the model.
- Oversized complete formatted results are saved through `ctx.spillStore.saveText()` when available while inline results stay bounded; spill failure, a missing backend, or a missing owner preserves the inline result and reports the unsaved remainder — never an `isError`.
- The package README, the generated config catalog, and exported JSDoc document the Config fields and `SEARCH_*` codes; the coding-agent example ships the tools (the acp-agent tree waits on the snapshot re-record above); the fs group README records the co-located bash/filesystem deployment requirement.
## Risks
Full-run `grep` can be slower than an early-stop search on broad patterns. The v1 accepts that cost for simpler implementation and complete-result recovery, bounded by tool timeout, bash timeout, `rawOutputMaxBytes`, and output caps. If this proves too slow, the direct-ripgrep or foreground-streaming alternatives remain available.
Shell command construction is the sharpest safety edge. Because `ctx.bash` accepts a command string rather than an argv vector, the implementation must centralize shell quoting and test malicious patterns, paths with spaces, leading-dash patterns, quotes, newlines, and glob metacharacters.
The v1 assumes a co-located bash/filesystem deployment. If bash searches one workspace and the `read` tool resolves paths against another, returned paths may not be follow-up-readable. The package documents this requirement but does not verify it at runtime.
Spill locators are backend-owned. The current local backend returns local filesystem paths and works in deployments where `read`/`grep` can open those files; remote or workspace-confined deployments can use a backend whose locator and retrieval hint point at a supported retrieval mechanism.

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# RFC: Expose agent session identity and JSONL location to tools and hooks
Status: implemented
## Problem
An agent can identify its workspace through `session.header.cwd`, but a model using bash cannot reliably identify the session that owns the call or the durable transcript that records it. Searching `./.sessions` guesses deployment config and JSONL layout; custom roots, alternate persistence backends, resume, forks, and concurrent parent/child agents make that guess unreliable. Hooks have the same need for transcript location, while future plugins may need to expose other harness-owned environment facts to shell commands.
The boundary must preserve two properties: the owner of a fact decides how to resolve it, and every child receives a per-execution snapshot rather than process-global mutable state. In particular, a nested harness must not leak its ambient `DSH_*` values into a child whose current agent, persistence backend, or configuration differs.
## Decision
Extend the [`SessionPersistence`](../../implemented/architecture/2026-06-14-session-persistence.md) seam with a synchronous, side-effect-free location query:
```ts
import type { SessionHeader } from '@deepseek-ai/dsh-session'
interface SessionLocation {
readonly kind: string
readonly path: string
}
interface SessionPersistence {
locate(meta: SessionHeader): SessionLocation | undefined
}
```
`path` is an absolute local path to the backend's dedicated log for `meta`; `kind` identifies the representation. JSONL returns `{ kind: 'jsonl', path }` using its resolved root and path helpers. SQLite and any backend without an honest local per-session artifact return `undefined`. The query creates and flushes nothing, so it can report a lazy target path before that file exists.
The model-facing bash package owns a `ctx.bashEnv` registry. A contributor declares its stable name, every `DSH_*` key it may return, a description for each key, and `resolve(execution: ToolExecution)`. Duplicate contributor names, duplicate key ownership, reserved keys, malformed declarations, undeclared runtime output, and non-string output fail loudly. Registration is a Cordis effect and is removed with the contributing plugin fiber. `list()` exposes declarations without running resolvers, keeping the environment surface enumerable for diagnostics and future prompt/UI consumers.
The registry rebuilds a trusted overlay for every foreground and background bash `ToolExecution`:
- `DSH_HOME` is always the absolute configured Harness home. The standalone [`@deepseek-ai/dsh-home`](../../../../packages/util/home/README.md) utility owns its precedence: explicit `dshHome`, then ambient `$DSH_HOME`, then `~/.dsh`.
- `DSH_SHELL=1` is always present and identifies a model bash child managed by DeepSeek Harness.
- `DSH_SESSION_ID` is present when the execution has an agent and equals `agent.session.header.id`.
- The built-in persistence translator contributes `DSH_SESSION_JSONL` only when `ctx.sessionPersistence.locate(header)` returns `kind: 'jsonl'`.
Session persistence remains the fact owner: JSONL does not depend on tool-bash or register shell variables itself, and hooks continue to consume `locate()` directly. Tool-bash is the translation layer from the persistence fact into a shell convention. Other plugins that need shell-visible facts depend on the registry and register their own keys; they do not modify `process.env`.
The bash seam exports `DSH_ENV_PREFIX` as the single namespace source and derives `DshEnvironmentKey` from its `typeof`. Tool-bash derives built-in names and model guidance from that constant, while executors use it for filtering and channel validation. The seam carries the managed overlay separately as `BashExecRequest.dshEnv` / `BashExecSpec.dshEnv`. Ordinary `env` remains the general in-process plugin surface used by hooks, but cannot contain managed keys; symmetrically, `dshEnv` cannot contain ordinary keys. The local executor rejects either wrong channel before spawn, removes every inherited ambient managed key, applies its ordinary scrub/terminal environment/explicit `env`, and finally merges the trusted `dshEnv` snapshot. This guarantees that a missing value means absent now rather than inherited from an outer or previous harness. The model-facing tool still ignores model-supplied `env`/`stdin` arguments.
The bash tool description teaches only the durable convention: current harness environment facts are available through managed `$DSH_*` variables and may be inspected when needed. It does not enumerate persistence-specific keys or add a permanent system-prompt section. Tool schemas are already logged in request headers and tool output is logged as `tool/result`, so no new session event is required.
The [Claude Code and Codex hook bridges](../../implemented/feature/2026-06-30-hook-bridges.md) resolve transcript location from the same persistence seam when constructing payloads. Codex uses `transcript_path: string | null`; Claude Code preserves its string field and falls back to `''`. Hook lookup neither materializes nor flushes a session.
## Peer product findings
Peer products separate stable identity from physical storage. Codex injects stable `CODEX_THREAD_ID` into spawned shells while recorder and hook surfaces own transcript paths. Claude Code supplies `session_id` and `transcript_path` as structured hook/status input. OpenCode carries identity in structured tool context; Kimi Code expands a session placeholder; Reasonix keeps the active session path on its controller. The portable rule is to inject identity at the invocation boundary, let storage resolve location, and never use a process-global current-session variable in a concurrent harness.
## Lifecycle and persistence semantics
A fresh session receives its id before the first turn, so its first bash call can read `DSH_SESSION_ID` and a JSONL target. The JSONL file may still be absent until the first successful turn-end checkpoint, and during an open turn it contains only the last flushed prefix. `DSH_SESSION_JSONL` is a location hint, not an authorization credential or freshness guarantee.
Resume reuses the loaded header and therefore the same id and location. Fork and spawn create new session ids and locations. Parent and child calls resolve from their own `ToolExecution.agent`; each command receives an immutable snapshot even when calls overlap. A persistence service replacement affects later collections because the translator queries `ctx.get('sessionPersistence')` at execution time; the registry itself is effect-scoped and HMR-safe.
`dshHome` is session-independent deployment context. Agent-core resolves one value through `@deepseek-ai/dsh-home` and routes it to both tool-bash and local skill discovery; standalone consumers call the same resolver. If top-level `dshHome` and `skills.local.dshHome` are both supplied and resolve differently, composition fails instead of exposing contradictory homes. Persistence may change independently without freezing its facts into the session prefix.
## Testing
Unit coverage pins registry declaration validation, effect disposal, per-execution collection, the `dshHome` precedence, and the local executor's `DSH_*` scrub/rebuild order. Request-recording tests cover foreground/background snapshots, no-agent calls, absent/JSONL persistence, ignored model `env`, and parent/child isolation. JSONL/SQLite locator contract tests and both hook bridge suites pin available and unavailable transcript dialects.
A keyless full-loop integration drives the real agent loop, JSONL persistence, tool-bash, and bash-local on the first turn. The child prints `DSH_HOME`, `DSH_SHELL`, session id, JSONL target, and an inherited stale sentinel; the test verifies current values, absence of the stale variable, pre-flush file absence, and the eventual persisted header. Snapshot coverage pins the generic bash description in the recorded request header. No with-key test is required because the contract is deterministic local execution rather than model choice.
## Alternatives considered
**Only an id plus `find`.** Search cannot know a custom root or backend layout and races under multiple sessions.
**Only an absolute path.** A path can be unavailable, lazy, or representation-specific and is not stable session identity.
**Global `process.env`.** Concurrent agents would overwrite one another and nested harnesses would inherit stale current-session values.
**Put persistence instructions in the session prefix.** A session prefix is frozen while the active service can change across HMR or future backend switching; persistence-specific guidance would become stale.
**A typed waterfall event.** Listeners cannot declare ownership without running, and later listeners can silently overwrite keys. A registry detects key conflicts at registration and remains enumerable.
**Have each persistence backend register bash env directly.** That reverses the dependency from storage into one consumer and forces bash into deployments that do not use it. `locate()` is also still required by hooks.
**A model-facing `session_info` tool.** It adds schema and another call while bash already supplies the query surface; the registry generalizes to future environment facts without one tool per fact.
## Consequences
Every model bash child receives current Harness home and shell identity, and agent calls additionally receive stable session identity. JSONL-backed calls get an optional target path; non-file persistence omits it honestly. The complete `DSH_*` namespace inside these children is managed by the harness: ambient values are removed, current trusted values are re-added, and ordinary callers cannot use `env` to bypass ownership checks.
The namespace is discoverable but not secret. Paths can reveal configured roots, lazy targets can be absent or stale, and a command can override variables inside its own shell syntax. Consumers treat them as correlation and environment facts, verify transcript metadata when attribution matters, and rely on sandbox/filesystem policy rather than variable secrecy for authorization.

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# RFC: Exact session query service
Status: implemented
## Problem
Session history exists in two places: current `SessionStore` objects and an optional persistence backend. Consumers that need exact inspection would otherwise duplicate live-versus-persisted precedence, persistence lifecycle handling, raw-event surface classification, relationship tracing, and defensive cloning. Durable state can lag the live log between checkpoints, so persistence alone is not a truthful current source.
Full-text search is related but materially larger. Designing provider registration, extraction, synchronization, invalidation, ranking, and cursor contracts before a real backend exists creates two speculative state machines: one in the interface service and another in the eventual database package.
## Decision
`@deepseek-ai/dsh-session-query` owns `ctx.sessionQuery`, a small trusted exact-inspection service over one logical corpus. It exposes `listSessions()`, `listEvents(sessionId)`, bounded `readEvent(request)`, `traceSession(sessionId)`, and `traceEvent(request)`. It does not expose filters, text extractors, search requests, provider registration, or derived-index synchronization. The separate [tracing decision](2026-07-13-session-query-tracing.md) owns lineage and event-relationship semantics.
The service observes the optional `ctx.sessionPersistence` binding dynamically but retains no persisted cache or invalidation listener. Each cross-corpus list asks the active backend for authoritative metadata, then overlays a fresh live-store list. Matching ids become one `SessionRecord`: the live header wins and `live`/`persisted` independently report source availability. Immutable header disagreement is `SESSION_QUERY_SOURCE_CONFLICT`.
An exact target read first checks the live store and snapshots the live header and event log. This path never consults persistence, so a failing durable backend cannot make known live history unreadable. With no live target, the service lists current persistence metadata, proves the id exists, loads it, and rejects a list/load header mismatch. All returned headers and events cross one structured-clone boundary.
## Surface semantics
`dsh-session` exports `foldSurface(events)`, and `SurfaceManager` uses the same transition functions for its incremental cache. The fold returns detached current nodes and each replacement's actual removed seqs. `listEvents()` and `traceEvent()` use that result to classify every raw event, so inspection cannot disagree with model-history derivation about positional replacement semantics.
`readEvent()` returns the complete target plus raw neighbors by contiguous seq. `before` and `after` default to zero and are independently bounded by `readWindowMax`, default 50. The result carries a cloned `SessionHeader`, not a source-availability record, because determining a live target's persisted flag would violate the guarantee that live exact reads do not depend on persistence health.
## Security boundary
The service is context-wide trusted infrastructure, not an authorization layer. A future model-facing history tool or human UI applies explicit caller/session scope. The service adds no model-facing tool and changes no transcript or snapshot surface.
## Alternatives considered
- **Put logical-corpus resolution directly in every consumer** — rejected because source precedence, conflicts, optional-service lifecycle, cloning, and surface classification are shared correctness rules.
- **Query only persistence** — rejected because checkpoints can lag the current live log.
- **Cache persisted metadata and listen for writes/removals** — rejected because exact reads can ask the authoritative sources directly, while cache invalidation adds lifecycle and concurrency state before scale requires it.
- **Define a provider-neutral search protocol now** — rejected because no provider consumes it. The first SQLite FTS package should own one reconciliation/transaction state machine; a smaller shared seam can be extracted later only when a second implementation proves the boundary.
## Consequences
The service has one source-resolution state variable: the currently mounted persistence service. There are no provider queues, fingerprints, extractor registries, observation generations, or derived index updates. Exact reads and event traces remain usable in live-only deployments and deterministic when persistence is present.
Cross-corpus listing, lineage tracing, and persisted event operations perform backend I/O on each call. That is deliberate: correctness comes from current authoritative state, and scale-oriented search belongs to the proposed database package. Full-text search is unavailable until that package defines and implements its complete contract.

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# RFC: Configure subagent persona, tool visibility, and depth
Status: implemented
## Problem
A reusable subagent provider answers how to run a child, but different delegation tools need different child behavior. One deployment may want a reviewer persona, a research-only tool set, or a hard recursion bound without creating a new provider for every combination.
These controls affect the child's first model request and therefore cannot be installed after the child is visible. They also need honest provider support: an ACP backend cannot silently accept an in-process-only tool filter, and a filter must not be described as a security boundary when every plugin runs in the same trusted process.
## Decision
Subagent starts have three independent composition controls: `persona`, `toolFilter`, and `maxDepth`. A provider advertises support for each control, the service rejects unsupported requests before starting a run, and an in-process provider installs the requested composition while the child is still unpublished.
The controls answer different questions:
| Control | Question | Result |
|---|---|---|
| `persona` | What role instructions replace the deployment persona for this child? | A child-local prompt section shadows `deployment:persona` |
| `toolFilter` | Which deployment-global tools enter this child's visible tool view? | A scoped restriction filters globals before child-local tools are added |
| `maxDepth` | How deep may this delegation tree grow? | A start whose child depth exceeds the absolute cap is rejected |
`dsh-tool-subagent` exposes the controls as plugin configuration and copies them into each request it creates. Direct `SubagentService` callers may choose them per request. The provider capability descriptor remains the source of truth for whether a backend can honor each field.
### Persona is a scoped shadow
The persona control changes one child without changing deployment-wide prompt assembly. During unpublished setup, an in-process provider registers a child-scoped section named `deployment:persona`; ordinary most-specific-wins resolution replaces the global section only in that child's assemblies.
The value has the same strict template semantics as the deployment persona. Omitting it inherits the deployment section through the global layer; an explicit empty string shadows the global persona with an empty section. Parent and sibling personas never enter the child's flat scope.
This uses the normal system-prompt registration mechanism rather than a second persona channel. The first prompt therefore sees the same named contribution that later prompts and prompt-inspection tools see.
### Tool filtering is one live global-view rule
The tool filter controls capability visibility and executable lookup together. An in-process provider installs `ToolRegistry.restrict()` in the child's scope before publication, and the registry's single resolver applies the same result to wire tool schemas, lookup, execution, and Code Mode SDK generation. Independently registered system-prompt sections are outside `ToolRegistry`, so filtering a tool does not remove that plugin's standalone guidance.
Resolution follows these rules:
1. Each restriction applies `allow` before `deny` to the live deployment-global tool registry.
2. Multiple restrictions intersect, so every installed restriction must admit a global tool.
3. Child-scoped tools are added after global filtering and may shadow an admitted global tool.
4. Reserved `run_code` presentation and other scope-local protocol contributions are outside the global filter.
Configuration fails loudly when a filter supplies neither `allow` nor `deny`, or names something outside the current global restrictable set, including a scope-local-only or reserved name. `allow: []` is valid and deliberately hides every global tool. These checks catch misspellings and prevent configuration from appearing effective when it cannot affect the named entry.
The global registry remains live. A deny-only filter admits a later global name unless it explicitly denies that name; an allow-list excludes a later global name unless it explicitly allows that name. Removing a global tool removes it from every resolved view. These semantics preserve hot registration while making the difference between allow and deny explicit.
### Depth is an absolute tree cap
The depth limit bounds recursive delegation independently of tool visibility. A top-level agent has depth zero; an in-process child has its parent's validated depth plus one. `maxDepth` is an absolute non-negative safe integer, and a start rejects before child ownership begins when the derived child depth is greater than the cap.
Every public entry validates the domain rather than relying on one model-facing configuration path. Negative values, fractions, negative zero, non-finite values, unsafe integers, malformed stored parent depth, and derived overflow all reject. Omitting the cap leaves depth unbounded by this mechanism.
A deployment can combine depth and filtering. For example, it may keep the delegation tool visible at depth one but set `maxDepth: 1`, or deny the delegation tool entirely in children. Neither choice changes the provider's conversation-history behavior.
### Capability gating keeps providers honest
Capabilities separate a requested feature from a provider implementation. `SubagentCapabilities` advertises `persona`, `toolFilter`, and `depthLimit`; `SubagentService.start()` checks every present request field against those flags before calling the provider.
This lets spawn and fork providers share the in-process implementation while external providers advertise only what they can enforce. A request never degrades silently: selecting an unsupported control produces `UNSUPPORTED_CAPABILITY`, and no run or lifecycle event exists.
### Unpublished setup makes the first request correct
All child-local composition is complete before the child becomes observable. The in-process provider supplies one setup callback to agent creation; that callback installs persona, tool restriction, and structured-output contributions in the child's scope. Only after setup succeeds does creation publish the session and agent and allow the driver to start.
A setup failure rolls back the private child. No observer can acquire a child whose first prompt used the deployment persona or unfiltered tool set and whose later prompts use the requested configuration.
## Visibility is not authority
These controls compose trusted same-process behavior; they do not authorize it. `toolFilter` changes the child view resolved by the tool registry, but it does not create a parent-to-child grant lattice, require a child to be a subset of its parent, sandbox plugins, or prevent code with another Cordis context from calling services directly.
In particular, a child-local tool is added after the global filter and may be absent from the parent's view. A deny-only child also sees later global tools not named by the deny-list. Those are deliberate live-composition semantics, not non-escalation guarantees.
A security design would need a separate authority representation, propagation rule, and execution-time enforcement point. Creation-time grant snapshots, parent-subset grants, explicit future-grant APIs, and generic capability/output/termination tags are outside this feature.
## Alternatives considered
**Create one provider per persona or tool set.** This multiplies providers that share the same transport and lifecycle implementation, makes dynamic deployment configuration awkward, and still needs a recursion mechanism. Providers remain about execution transport; requests carry per-child composition.
**Copy the parent's complete tool view.** Registration scope is flat by design, and lifetime ownership does not imply visibility inheritance. Copying a resolved view would also freeze dynamic global registrations and conflate composition with authority without defining either contract fully.
**Snapshot allowed global tools at child creation.** A frozen allow-set makes future registration uniformly unavailable, but it changes hot-registration semantics and starts an authorization design. The implemented filter stays a live registry predicate and documents allow-versus-deny behavior directly.
**Hide only tool schemas.** Presentation-only filtering lets the model execute a tool that the prompt says does not exist through Code Mode or a forged call. One resolver governs both presentation and execution instead.
**Use only tool filtering to stop recursion.** Removing the delegation tool is useful but provider-specific and does not protect direct service callers or alternate delegation tools. Absolute depth is an independent structural bound.
## Consequences
Contributors can configure child role, visible global tools, and recursion without defining new providers. Capability checks fail before ownership starts, unpublished setup makes the first request consistent, and one tool resolver prevents presentation/execution drift.
The cost is that deployments must understand live allow/deny behavior and the distinction between visibility and authority. Provider authors must advertise each supported control accurately, and in-process providers must install every requested contribution before publication. The controls deliberately do not solve security confinement or parent-to-child non-escalation.

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# RFC: Session query relationship tracing
Status: implemented
## Problem
Session relationships are encoded across immutable headers, positional surface operations, and logged provenance arrays. A consumer reconstructing those relationships directly would need to duplicate corpus precedence, surface folding, malformed-log handling, deterministic lineage ordering, and cloning. Positional replacement and provenance are different graphs, so collapsing them into one generic edge type would also lose meaning.
## Decision
`ctx.sessionQuery` exposes `traceSession(sessionId)` and `traceEvent({ sessionId, seq })` alongside its exact reads. Both are one-shot views over the existing live-preferred corpus: session tracing consumes one complete corpus listing, while event tracing consumes one loaded logical log and one canonical surface fold. The service retains no lineage, reverse-index, or replacement state after a call.
`SessionLineageTrace` returns the target, known parents in immediate-to-outward order, and recursive descendant trees whose siblings sort by creation time and then session id. `complete: true` carries the known root; `complete: false` carries the first unresolved parent id. A cycle connected to the target fails with `SESSION_QUERY_INVALID_LINEAGE`.
`SessionEventTrace` keeps positional and provenance relationships separate. `replacedBy` is the immediate positional replacer, `replacementChain` follows replacers to the final node, and `replacedEventSeqs` lists the actual surface nodes directly removed by the target. `sourceEventSeqs` preserves direct logged source order, while `derivedEventSeqs` lists later direct reverse references in log order. Provenance is not expanded transitively.
## Validation boundary
Event tracing checks target existence before surface analysis. Both event listing and tracing then use `dsh-session`'s one-pass surface fold, which accepts or rejects the loaded log as a whole: event seqs are zero-based and contiguous, surface markers obey event-type eligibility, provenance belongs only to surface event types, present arrays are nonempty and duplicate-free, every source is an earlier seq, and every positional replacement names and cites all surface nodes it removes. Every contract failure uses `SESSION_QUERY_INVALID_SURFACE`; there is no weaker classification-only surface standard.
All returned records and arrays are detached. A known live event trace never consults persistence; persisted event traces preserve the exact-read list/load consistency check. Session lineage is necessarily a cross-corpus operation and therefore preserves cross-corpus persistence failure semantics.
## Alternatives considered
- **Expose standalone tracing helpers** — rejected because the source-precedence and detachment boundary belongs to `ctx.sessionQuery`; public helpers would invite callers to bypass it.
- **Combine replacement and provenance edges** — rejected because a positional replacement can shadow surface nodes while also citing non-surface construction inputs, and consumers need to distinguish those meanings.
- **Return transitive provenance closure** — rejected because it obscures logged direct evidence, increases result size, and lets one malformed distant edge alter otherwise local output.
- **Best-effort traces over malformed provenance** — rejected because a structurally plausible partial graph would look authoritative. Exact inspection fails loudly when the canonical relationship contract is broken.
## Consequences
Consumers receive deterministic relationship views without a cache or second corpus. Event tracing performs whole-log validation and allocation on each call, while lineage tracing lists the complete logical corpus on each call. Those costs keep the source of truth explicit and are separate from the content-bearing full-text-search and filtering API.
The feature has unit and service-level coverage but no snapshot or end-to-end fixture because it introduces no model-facing consumer, transcript change, or cross-process protocol.

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# Bilingual-pair consistency record (docs/i18n/README.md): the git blob hash of each
# side as of the last confirmed-consistent state. Both languages carry equal authority;
# after editing either side, bring the other along and re-record with:
# pnpm run verify-translation-pairing --write
2026-07-14-time-context-plugin.md: aa24c6246718cfe0bb3ed63d0791cf890514d9fe
2026-07-14-time-context-plugin.zh.md: e939ff1d0cb250f3fa7a7db34b50d92760e3374d

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# RFC: Optional time-context plugin
Status: implemented
English | [中文](2026-07-14-time-context-plugin.zh.md)
## Problem
The dynamic system-prompt storage and refresh decision in this record is superseded by [Durable per-step time context](2026-07-16-durable-per-step-time-context.md). The opt-in package, zoned formatting, and validation remain; the follow-up owns the current model-visible and durability contract.
An agent request has no live clock unless a deployment puts one in prompt text or gives the model a query tool. Static text becomes stale, while a tool call adds overhead to ordinary reasoning about dates, deadlines, or idle time. Without elapsed time, the model cannot distinguish an immediate follow-up from one sent hours after the preceding message.
Prompt assembly can derive both facts per step from durable session timestamps, and request-header logging can record the exact rendered value. Accumulating stale readings in conversation history or waking idle agents would violate the existing request lifecycle.
## Decision
`@deepseek-ai/dsh-time-context` is an opt-in function plugin at `packages/context/time-context/`. The `context/` product group holds bounded request-context enrichments that define neither a tool nor a service. `dsh-agent-spine-demo` and shipped examples do not load the package; deployments mount it explicitly when its token and disclosure costs are acceptable.
The plugin registers the global `context:time` system-prompt section at order 10, after the deployment persona and before tool guidance. For an active turn it emits an ISO-shaped timestamp with numeric UTC offset and IANA zone, plus a compact whole-second duration since the last model-visible message before the turn opened. Bare and idle assemblies receive an empty section.
### Previous-message baseline
At a turn's first assembly, the provider scans before `turn/start` for the latest `user/message`, `assistant/message`, `tool/result`, `context/message`, or `steering/message`. It excludes the current prompt so the duration expresses the inter-turn gap instead of approximately zero. Every refresh in that turn keeps the same baseline, and the first turn reports `unavailable (no earlier message in this session)`.
The baseline is the session event's append time, not an unlogged client timestamp. Resume and fork behavior are therefore deterministic from the durable log, and the model-visible value remains reconstructable without a new event. A backward wall-clock adjustment clamps the duration to zero.
### Refresh policy
`refreshIntervalMs` defaults to 60,000 and must be a non-negative safe integer. Every turn's first request refreshes. Later assemblies in that turn reuse the block until its age reaches the interval; `0` refreshes every step. No timer creates work during model calls, tools, or idle time because refresh is request-bound.
When `timeZone` is omitted, `Intl.DateTimeFormat` resolves the Node process's system zone once at plugin load. Node honors `TZ`; without that override, the host or container supplies the zone. An explicit value must be an IANA identifier and is validated at load. The captured zone remains stable until plugin reload, and the ISO-shaped local timestamp includes its current numeric offset so daylight-saving changes stay explicit. This is the deployment process's zone, not a remote user's zone.
### Logging and token shape
The loop records the temporal block through `request/header` and `request/header-delta` before transmission, satisfying the [reconstructable-requests contract](../architecture/2026-07-05-reconstructable-requests.md). Each request carries one current block; earlier readings do not remain in conversation history. The plugin owns the fact and contributes it through the prompt registry, following the [prompt-variables RFC](../architecture/2026-07-05-prompt-variables-and-tool-guidance-ownership.md) without a loop special case.
## Testing
Unit tests pin formatting, baselines, refresh policy, validation, per-agent state, disposal, and load-time system-zone capture. A real agent-loop test pins the transmitted prompt and `request/header-delta`. A keyless subprocess e2e boots a test-only `cordis.yml` through the real Loader and stdio app, omits `timeZone` under a controlled `TZ`, drives two turns, and verifies the persisted request headers externally. Default snapshot compositions omit the plugin, so their transcript fixtures contain no temporal block.
## Alternatives considered
- **Append a `context/message` on every turn or refresh** — rejected because readings and token cost would accumulate in history. Replacing a prior surface node would preserve its old position, while replacing the tail would hide intervening conversation.
- **Use `agent/session-prefix`** — rejected because the session-stable prefix cannot represent a per-turn or per-step clock.
- **Mutate requests in `agent/request`** — rejected because that seam shapes call config after the message boundary; inserted model content would bypass prompt-pressure accounting and request-header logging.
- **Register separate `{{current_time}}` and `{{elapsed}}` variables** — rejected because independent providers can sample different instants and require shared caching. One section records the pair atomically without a deployment-authored template.
- **Refresh from a background timer** — rejected because a new value has no consumer outside request assembly. Timer-driven `agent.inject()` would create turns and wake idle sessions merely to report time passing.
- **Keep UTC as the omitted default** — rejected because an explicitly enabled clock should follow its deployment environment unless the operator chooses UTC. `timeZone: UTC` remains available when a deployment requires it.
- **Add a time-zone detection library** — rejected because Node's `Intl` runtime already exposes the process's IANA zone. Another dependency cannot infer a remote user's zone either.
- **Mount the plugin in `dsh-agent-spine-demo`** — rejected because time zone, disclosure, token budget, and freshness are deployment policy. Opt-in keeps default context stable.
- **Place the package in `core/`** — rejected because `core/` owns the product API spine, while this plugin is an optional leaf with no service key.
## Consequences
- Opted-in models receive a zoned clock and inter-turn duration without a tool call. The system-prompt cost is fixed per request instead of growing with the session.
- An omitted `timeZone` follows the process's `TZ`, host, or container zone as observed at plugin load. Operators must configure an explicit zone when the deployment environment does not represent the intended user.
- A refresh changes the request header and can add a `request/header-delta`. `refreshIntervalMs` trades freshness against durable deltas; `0` records a new value on every step whose whole-second rendering changes.
- No request exists solely to refresh time. A long-running tool leaves the prior reading until the next step assembles.
- Duration reflects harness processing time at durable append boundaries, not client-network latency before logging. Preserving a client-origin timestamp requires a separate durable input contract.

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# RFC可选时间上下文插件
Status: implemented
[English](2026-07-14-time-context-plugin.md) | 中文
## 问题
本记录中的动态系统提示词存储和刷新决策已由[持久的逐步骤时间上下文](2026-07-16-durable-per-step-time-context.md)取代。需要显式启用的包package、分区时间格式和校验仍然保留后续 RFC 负责当前的模型可见与持久性契约。
如果部署方既未在提示词中提供时钟也未给模型提供查询工具agent智能体请求就无法获得实时准确的时间。静态文本会变得陈旧而对于日期、截止时间或闲置时长等常规推理调用工具会增加开销。缺少已经过去的时长时模型无法区分紧接着发送的消息与上一条消息几小时后才发送的消息。
提示词组装流程可以在每个步骤中根据持久会话时间戳派生这两项信息,请求头日志则可以记录实际渲染的确切值。在会话历史中累积陈旧读数或唤醒空闲 agent 都会违反现有请求生命周期。
## 决策
`@deepseek-ai/dsh-time-context` 是位于 `packages/context/time-context/`、需要显式启用的函数插件。`context/` 产品分组用于容纳既不定义工具、也不定义服务的有界请求上下文增强。`dsh-agent-spine-demo` 和仓库提供的示例都不会加载该包;只有当 token 与信息披露成本可接受时,部署方才显式挂载它。
该插件注册顺序值为 10 的全局系统提示词区段 `context:time`,位置在部署方角色设定之后、工具指导之前。对于活跃轮次,它会输出带数字 UTC 偏移和 IANA 时区、形似 ISO 的时间戳,以及从轮次开始前最后一条模型可见消息起算的紧凑整秒时长。未绑定 agent 或 agent 处于空闲状态时,该区段为空。
### 上一条消息基线
在轮次首次组装时,提供方会在 `turn/start` 之前查找最近的 `user/message``assistant/message``tool/result``context/message``steering/message`。它会排除当前提示词,使时长表达轮次间隔,而不是接近零。同一轮次中的每次刷新都保留这条基线;首个轮次报告 `unavailable (no earlier message in this session)`
基线采用会话事件的追加时间,而不是日志中不存在的客户端时间戳。因此,恢复和 fork 行为可以从持久日志中确定性重现,模型可见值也无需新增事件即可重建。系统挂钟向后调整时,插件会将时长钳制为零。
### 刷新策略
`refreshIntervalMs` 默认值为 60,000并且必须是非负安全整数。每个轮次的首次请求都会刷新。同一轮次中的后续组装会复用该区块直至其存在时间达到该间隔设为 `0` 时每个步骤都刷新。刷新仅由请求驱动,因此在模型调用、工具运行或空闲期间,计时器不会创建任务。
省略 `timeZone` 时,`Intl.DateTimeFormat` 会在插件加载时解析一次 Node 进程的系统时区。Node 会遵循 `TZ`;没有该覆盖值时,时区由主机或容器提供。显式值必须是 IANA 标识符,并在加载时接受校验。捕获的时区在插件重新加载前保持稳定,形似 ISO 的本地时间戳包含其当前数字偏移,使夏令时变化保持显式可见。该默认值代表部署进程的时区,而不是远程用户的时区。
### 日志与 token 形态
agent loop智能体循环会在发送前通过 `request/header``request/header-delta` 记录时间区块,从而满足[可重建请求契约](../architecture/2026-07-05-reconstructable-requests.md)。每个请求只携带一个当前区块;先前的读数不会保留在会话历史中。该插件拥有时间信息,并按照[提示词变量 RFC](../architecture/2026-07-05-prompt-variables-and-tool-guidance-ownership.md)通过提示词注册表贡献该信息,无需为循环添加特殊分支。
## 测试
单元测试固定格式化、基线、刷新策略、校验、逐 agent 状态、资源释放行为,以及系统时区在加载时的捕获行为。使用真实 agent loop 的测试固定实际发送的提示词和 `request/header-delta`。无密钥子进程端到端测试通过真实 Loader 和 stdio 应用启动测试专用 `cordis.yml`,在受控 `TZ` 下省略 `timeZone`,驱动两个轮次,并从外部校验持久请求头。默认快照组合不包含该插件,因此其中的 transcript文本记录fixture测试前置数据不包含时间区块。
## 考虑过的替代方案
- **每个轮次或每次刷新都追加一条 `context/message`**——不予采纳,因为读数和 token 成本会在历史中累积。替换先前的表层节点会保留其旧位置,而替换尾部节点会隐藏中间的会话内容。
- **使用 `agent/session-prefix`**——不予采纳,因为会话期间保持稳定的前缀无法表示逐轮次或逐步骤变化的时钟。
- **在 `agent/request` 中修改请求**——不予采纳,因为该边界在消息边界之后塑造调用配置;插入模型可见内容会绕过提示词压力核算和请求头日志。
- **注册独立的 `{{current_time}}``{{elapsed}}` 变量**——不予采纳,因为独立提供方可能在不同时间点采样,并且需要共享缓存。单个区段会以原子方式记录两项信息,也不需要部署方编写时间模板。
- **通过后台计时器刷新**——不予采纳,因为请求组装之外没有消费新值的对象。由计时器驱动 `agent.inject()` 会创建轮次,并且只为报告时间流逝就唤醒空闲会话。
- **省略配置时仍默认使用 UTC**——不予采纳,因为显式启用的时钟应跟随部署环境,除非运维方选择 UTC。需要 UTC 的部署仍可配置 `timeZone: UTC`
- **引入时区探测库**——不予采纳,因为 Node 的 `Intl` 运行时已经能够提供进程的 IANA 时区,而且额外依赖同样无法推断远程用户的时区。
- **在 `dsh-agent-spine-demo` 中挂载插件**——不予采纳因为时区、信息披露、token 预算和新鲜度都属于部署策略。选择加入能保持默认上下文稳定。
- **将包放入 `core/`**——不予采纳,因为 `core/` 负责产品 API 主干,而该插件是没有服务键的可选叶节点。
## 后果
- 选择加入的模型无需调用工具,即可获得分区时钟和轮次间隔时长。每个请求的系统提示词成本固定,不会随会话增长。
- 省略 `timeZone` 时,插件采用加载时观察到的进程 `TZ`、主机或容器时区。当部署环境不能代表目标用户时,运维方必须显式配置时区。
- 刷新会改变请求头,并可能新增 `request/header-delta``refreshIntervalMs` 用新鲜度换取持久增量记录的数量;设为 `0` 时,每个整秒渲染结果发生变化的步骤都会记录新值。
- 系统不会仅为刷新时间而创建请求。长时间运行的工具会保留先前读数,直至下一步骤开始组装。
- 时长反映持久追加边界处的 harness 处理时间,不包含消息进入日志之前的客户端网络延迟。若要保留客户端来源时间戳,需要单独的持久输入契约。

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# Bilingual-pair consistency record (docs/i18n/README.md): the git blob hash of each
# side as of the last confirmed-consistent state. Both languages carry equal authority;
# after editing either side, bring the other along and re-record with:
# pnpm run verify-translation-pairing --write
2026-07-16-durable-per-step-time-context.md: 12d8191eb72b3fabd3164f13a77d9944631b906e
2026-07-16-durable-per-step-time-context.zh.md: 977ffb7276011ac9ae9b8a72a726bb23baba0a2d

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# RFC: Durable per-step time context
Status: implemented
English | [中文](2026-07-16-durable-per-step-time-context.zh.md)
## Problem
A request-only clock can tell the model the current time, but replacing that value in the system prompt removes the evidence behind earlier time-sensitive reasoning. Multi-step turns need requests to retain the readings that shaped preceding steps. The request must remain reconstructable after restart, and automatic compaction must account for the same timing context the model receives.
A process-local refresh cache makes displayed time depend on state that cannot survive resume or be reconstructed from the durable session. Durable interval scheduling can reduce append frequency without introducing that hidden state.
## Decision
`@deepseek-ai/dsh-time-context` is an opt-in function plugin in `packages/context/time-context/`. It registers a prepended `agent/pre-step` listener and, when an injection is due, calls `agent.inject()` for a pre-step attempt whose signal is not already aborted. The injected `context/message` carries source `{ kind: 'plugin', plugin: 'time-context' }` and append surface metadata; a suppressed attempt appends nothing.
The listener records preparation context before a possible `step/start`. Its prepended registration runs before ordinary automatic compaction listeners, so pressure estimation and any resulting surface rewrite observe a newly appended reading. A later pre-step listener can cancel or fail the attempt before the step opens; the reading remains because the durable log is append-only and this plugin performs no rollback.
The optional `timeZone` config resolves the Node process's IANA zone once at plugin load when omitted; an explicit value is validated by `Intl.DateTimeFormat`. The timestamp includes the numeric UTC offset and resolved IANA zone.
The optional `refreshIntervalMs` config is manually validated at plugin load as a non-negative safe integer. Omission or `0` injects on every eligible preparation attempt. A positive value scans the raw session events for the most recent `context/message` with this plugin's source and injects when none exists, wall time moved backward, or the event is at least the configured age. The raw event timestamp governs even after compaction shadows the message, so scheduling persists across turns and process resume without a timer or process-local cache.
### Text and elapsed baselines
An injected first-step reading is:
```text
Time sampled while preparing turn <turn>, step 1: <timestamp>
Elapsed since the preceding model-visible message: <duration-or-unavailable>.
```
The baseline is the latest preceding user, assistant, tool-result, context, or steering message. This includes the accepted prompt that opened an ordinary message turn. If no model-visible message exists, the duration is `unavailable`.
An injected later-step reading is:
```text
Time sampled while preparing turn <turn>, step <step>: <timestamp>
Elapsed since the preceding step context: <duration-or-unavailable>.
```
Their baseline is the durable event timestamp of the preceding time-context message in the same turn. If interval suppression leaves no earlier same-turn reading, the duration is `unavailable`. Duration formatting uses compact whole-second units and clamps backward wall-clock movement to zero. The explicit turn and step make every retained reading attributable to its historical preparation attempt after later turns append more context.
### Durability and request reconstruction
Each reading remains a normal surface node until compaction shadows it; positive interval scheduling never removes existing readings. A later request therefore sees the cumulative unshadowed readings that affected earlier preparation and steps, rather than a system-prompt value rewritten in place.
The plugin contributes nothing to system-prompt assembly. `request/header` and `request/header-delta` contain no time-context text; request reconstruction obtains the complete durable surface prefix at each `step/start`. Readings and requests need not map one-to-one because a failed preparation can leave a reading while interval suppression can prepare a request without appending one. The plugin depends on the agent registry for its lifecycle listener and does not require the system-prompt service at runtime.
## Testing
Unit and real-loop tests pin formatting, both elapsed baselines, interval omission and zero, threshold boundaries, cross-turn and per-session scheduling, backward-clock behavior, invalid config, resumed raw-event lookup after compaction, aborted-signal behavior, later-listener cancellation and failure, listener disposal, source and surface metadata, cumulative multi-step visibility, and absence from request headers. A keyless subprocess e2e boots the real Loader and stdio app, drives two turns, and verifies the persisted context events externally.
## Supersedes
This decision supersedes the dynamic system-prompt storage and refresh policy in [Optional time-context plugin](2026-07-14-time-context-plugin.md). It keeps the package location, opt-in deployment stance, timestamp formatting, process-zone default, and load-time validation. Durable history replaces the `context:time` prompt section, process-local refresh cache, and request-header deltas; `refreshIntervalMs` controls durable append frequency instead of prompt replacement.
## Alternatives considered
- **Keep the dynamic system-prompt section and process-local refresh cache** — rejected because replacement erases earlier readings, cache state is not replayable, and a frozen request envelope would make the value stale for an entire loop instance.
- **Replace the preceding context surface node** — rejected because replacement preserves the old node's position or shadows intervening conversation; neither represents when the new reading became visible.
- **Inject from a background timer** — rejected because idle time has no pending request to consume the value, and timer-driven injection would create durable turns solely to report time passing.
- **Expose time only through a tool** — rejected because ordinary temporal reasoning would require an avoidable tool round trip and would not guarantee a reading before every step.
- **Use `agent/session-prefix`** — rejected because one loop-instance prefix cannot represent distinct step timestamps and does not accumulate historically attributable readings.
## Consequences
- Omission or `0` records every eligible preparation attempt; a positive interval reduces append frequency and history growth while preserving durable scheduling across resume.
- Timing context remains append-only until compaction shadows older surface nodes, including a preparation reading left by a later cancellation or failure.
- The first-step duration normally measures from the prompt that opened the turn, while later-step durations measure model and tool processing since the preceding step context.
- An omitted `timeZone` still reflects the deployment process rather than a remote user, and elapsed time still uses durable harness append boundaries rather than client-origin timestamps.

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# RFC: 持久的逐步骤时间上下文
Status: implemented
[English](2026-07-16-durable-per-step-time-context.md) | 中文
## 问题
仅存在于请求中的时钟可以告诉模型当前时间但在系统提示词中替换这个值会移除先前时效性推理所依据的证据。在包含多个步骤的轮次中请求需要保留影响先前步骤的读数。系统必须能在重启后重建请求自动压缩compaction也必须核算模型实际收到的同一份时间上下文。
进程本地刷新缓存使显示的时间依赖无法在恢复后保留、也无法从持久会话重建的状态。持久的间隔调度可以减少追加频率,而不引入这种隐藏状态。
## 决策
`@deepseek-ai/dsh-time-context` 是位于 `packages/context/time-context/`、需要显式启用的函数插件。它注册一个前置的 `agent/pre-step` 监听器,并在需要注入时,为信号尚未取消的预步骤尝试调用 `agent.inject()`。注入的 `context/message` 携带来源 `{ kind: 'plugin', plugin: 'time-context' }` 和追加表层元数据;受间隔抑制的尝试不会追加任何内容。
监听器在可能出现的 `step/start` 之前记录准备上下文。它采用前置注册,因此先于普通自动压缩监听器运行,使压力估算和由此产生的表层重写都能观察到新追加的读数。后续预步骤监听器可能在步骤开启前取消尝试或使其失败;持久日志仅追加,且本插件不执行回滚,因此该读数会保留下来。
省略可选配置 `timeZone` 时,插件在加载时解析一次 Node 进程的 IANA 时区;显式值由 `Intl.DateTimeFormat` 校验。时间戳包含数字 UTC 偏移和解析后的 IANA 时区。
插件在加载时手动校验可选配置 `refreshIntervalMs`,其值必须为非负安全整数。省略或设为 `0` 时,每次符合条件的准备尝试都会注入。设为正数时,插件扫描原始会话事件,查找来源属于本插件的最新 `context/message`;不存在此类事件、系统挂钟向后移动,或该事件已达到配置时长时,插件执行注入。即使压缩已隐藏消息,调度仍以原始事件时间戳为准,因此该机制无需计时器或进程本地缓存,也能跨轮次和进程恢复持续生效。
### 文本与时长基线
第一个步骤的注入读数为:
```text
Time sampled while preparing turn <turn>, step 1: <timestamp>
Elapsed since the preceding model-visible message: <duration-or-unavailable>.
```
基线是前一条用户消息、助手消息、工具结果、上下文消息或 steering中途引导消息。对于普通消息轮次这包括开启轮次的已接受提示词。如果不存在模型可见消息时长为 `unavailable`
后续步骤的注入读数为:
```text
Time sampled while preparing turn <turn>, step <step>: <timestamp>
Elapsed since the preceding step context: <duration-or-unavailable>.
```
其基线是同一轮次中上一条时间上下文消息的持久事件时间戳。如果间隔抑制导致同一轮次中没有更早的读数,时长为 `unavailable`。时长采用紧凑的整秒单位,并在系统挂钟向后移动时钳制为零。显式的轮次号和步骤号使每个保留的读数在后续轮次追加更多上下文后,仍可归属于对应的历史准备尝试。
### 持久性与请求重建
每个读数都作为普通表层节点保留,直至压缩将其隐藏;正数间隔调度绝不会移除已有读数。因此,后续请求会看到影响先前准备过程和步骤且尚未被隐藏的累计读数,而不是一个被原地改写的系统提示词值。
插件不向系统提示词组装贡献任何内容。`request/header``request/header-delta` 不包含时间上下文文本;请求重建从每个 `step/start` 取得完整的持久表层前缀。读数与请求无需一一对应,因为失败的准备过程可能留下读数,而间隔抑制也可能使请求准备过程不追加读数。插件通过 agent 注册表使用生命周期监听器,运行时不需要系统提示词服务。
## 测试
单元测试和真实 agent loop智能体循环测试固定格式化、两种时长基线、间隔省略和零值、阈值边界、跨轮次和各会话独立调度、挂钟后退行为、无效配置、压缩后基于恢复会话的原始事件查找、已取消信号行为、后续监听器取消和失败、监听器 dispose资源释放、来源与表层元数据、多步骤累计可见性以及请求头中不存在时间上下文。无密钥子进程 e2e 测试通过真实 Loader 和 stdio 应用启动,驱动两个轮次,并从外部校验持久化的上下文事件。
## 取代的决策
本决策取代[可选时间上下文插件](2026-07-14-time-context-plugin.md)中的动态系统提示词存储和刷新策略。它保留包位置、选择加入式部署、时间戳格式、进程时区默认值和加载时校验。持久历史取代 `context:time` 提示词区段、进程本地刷新缓存和请求头增量;`refreshIntervalMs` 用于控制持久追加频率,而非提示词替换。
## 考虑过的替代方案
- **保留动态系统提示词区段和进程本地刷新缓存**——不予采纳,因为替换会抹去先前读数,缓存状态无法回放,而且冻结的请求内容集合会使该值在整个 agent loop 实例期间保持陈旧。
- **替换前一条上下文表层节点**——不予采纳,因为替换会保留旧节点的位置或隐藏中间的会话内容;两者都不能表达新读数何时开始可见。
- **通过后台计时器注入**——不予采纳,因为空闲期间没有待处理请求消费该值,而且计时器驱动的注入会仅为报告时间流逝而创建持久轮次。
- **只通过工具提供时间**——不予采纳,因为普通时间推理会产生本可避免的工具往返,也不能保证每个步骤之前都有读数。
- **使用 `agent/session-prefix`**——不予采纳,因为一个 loop 实例前缀无法表示不同的步骤时间戳,也不会累计具有历史归属的读数。
## 后果
- 省略 `refreshIntervalMs` 或设为 `0` 时,每次符合条件的准备尝试都会留下记录;正数间隔会减少追加频率和历史增长,同时使持久调度在恢复后继续生效。
- 时间上下文仅追加并保留到压缩隐藏旧表层节点为止,其中也包括后续取消或失败所留下的准备读数。
- 第一个步骤的时长通常从开启轮次的提示词起算,后续步骤的时长则反映自上一条步骤上下文以来的模型与工具处理时间。
- 省略 `timeZone` 时仍采用部署进程而非远程用户的时区,时长仍采用 harness 的持久追加边界而非客户端来源时间戳。

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@@ -11,10 +11,11 @@ This codebase is developed primarily by coding agents. Agents follow enforced ga
Every AGENTS.md promise gets a command that exits non-zero, wired into git hooks and CI both calling the same package.json scripts:
- Max-strict TypeScript (`noUncheckedIndexedAccess`, `exactOptionalPropertyTypes`, …); examples, tests, and scripts typecheck in CI via the root no-emit `tsconfig.json` while package/vendor code stays behind its own project-reference boundary.
- ESLint strict-type-checked + @stylistic (the house style, enforced); vendored code excluded.
- Per-file 100% coverage on `packages/*/src` (v8); unreachable defensive guards carry `/* v8 ignore */ ` with stated reasons instead of deletion.
- ESLint strict-type-checked + @stylistic (the house style, enforced), including file-local duplicated logic checks; vendored code excluded.
- jscpd detects cross-file clones in package production TypeScript and repository scripts; narrow source-range exceptions document deliberately parallel implementations.
- Per-file 100% coverage on `packages/*/*/src` (v8); unreachable defensive guards carry `/* v8 ignore */ ` with stated reasons instead of deletion.
- knip (dead code/deps), publint (package correctness), workspace constraints (workspace rules: private, cordis peer+dev, uniform version, ESM), and a NodeNext consumer typecheck for built package declarations.
- lefthook pre-commit (lint staged, typecheck, vendor-manifest guard) and pre-push (tests, hygiene); CI runs the full matrix on node 24/26 plus a demo smoke test driving the echo-agent end to end.
- lefthook pre-commit (lint staged, typecheck, vendor-manifest guard) and pre-push (tests, hygiene); CI runs the full matrix on node 22.19/24/26 plus a demo smoke test driving the echo-agent end to end.
## Consequences

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@@ -12,7 +12,7 @@ Build output currently matters only for `pnpm run build` + publint (nothing publ
Replace dumble with **tsdown** (rolldown-based, ~2.5M downloads/week, VoidZero-backed, actively released):
- Root `tsdown.config.ts` with `workspace: ['vendor/*', 'packages/*']` (explicit globs, not `workspace: true`, which would also pick up `examples/*` — they have package.json files but are not pnpm workspaces).
- Root `tsdown.config.ts` with `workspace: ['vendor/*', 'packages/*/*']` (explicit globs keep bundling to vendored Cordis and the TypeScript package tree; `workspace: true` would also discover example manifests and non-bundled workspace members).
- Shared shape: entry `lib/types/index.js`, `outDir: 'lib'`, ESM, `platform: node`, `target: es2024`, `fixedExtension: false` (keeps `.js` for `"type": "module"` packages), `dts: false` (tsc -b owns declarations), `clean: false` (lib/ also holds TSC's `lib/types` intermediate tree). The entry was originally `src/index.ts`; the [TSC-first build RFC](2026-06-17-ts-build-config.md) later moved tsdown to bundling TSC-emitted JS so TypeScript transform behavior comes from one compiler.
- Two per-package overrides in vendor/ (ours, like the regenerated tsconfigs; logged in vendor/README.md): schemastery (dual `.mjs`/`.cjs` via `outExtensions`), logger-console (two single-entry passes so the shared base class is inlined into each entry instead of a hash-named chunk, matching upstream's published shape).
- `scripts/build.ts` deleted; `pnpm run build` = `tsc -b tsconfig.build.json && tsdown`.

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@@ -15,7 +15,7 @@ Adopt **pnpm 11.7.0**, pinned via the `packageManager` field and installed throu
- **Workspaces** move from the `package.json` `workspaces` array + `.yarnrc.yml` to `pnpm-workspace.yaml` (`vendor/*`, `packages/*` — the same globs; `examples/*` stay non-workspace, matching the prior setup and tsdown's explicit globs).
- **Strict symlinked linker** (pnpm's default) replaces Yarn's hoisted `node-modules` linker. We deliberately add **no** `node-linker=hoisted` / `shamefully-hoist` escape hatch: pnpm's non-flat `node_modules` makes phantom dependencies (importing an undeclared transitive dep) fail loudly, which is a *feature* for a repo whose whole quality story is mechanical gates ([mechanical quality gates](2026-06-11-quality-gates.md)). The gate suite — typecheck, lint, test, build, knip — is the safety net that proves no such phantom imports exist.
- **Build-script allowlist.** pnpm 10+ does not run dependency lifecycle scripts unless allowlisted. `pnpm-workspace.yaml` carries an explicit `allowBuilds` map (`esbuild`, `lefthook`, `@google/genai`, `protobufjs`) — the same supply-chain-hardening posture the repo already takes toward model/tool output, now applied to install-time code execution. `peerDependencyRules.allowedVersions.typescript: '>=5 <7'` silences benign peer-range warnings for the in-repo TypeScript.
- **Constraints become package-manager-independent.** `yarn.config.cjs` (which imported `@yarnpkg/types` and used `Yarn.workspaces()` / `workspace.set()`) is replaced by `scripts/check-workspace-constraints.ts`, a plain tsx script run as `pnpm run constraints`. It enforces the identical invariants — every package `private: true`; `@deepseek-ai/dsh-*` packages declare `cordis` as both a peer- and dev-dependency with matching ranges, `version: 0.0.1`, `type: module`; vendored packages checked for privacy only — over the same `vendor` + `packages` scope.
- **Constraints become package-manager-independent.** `yarn.config.cjs` (which imported `@yarnpkg/types` and used `Yarn.workspaces()` / `workspace.set()`) is replaced by `scripts/check-workspace-constraints.ts`, a plain tsx script run as `pnpm run constraints`. It enforces the identical invariants — every package `private: true`; `@deepseek-ai/dsh-*` packages declare `cordis` as both a peer- and dev-dependency with matching ranges, use the root `package.json` version, and set `type: module`; vendored packages checked for privacy only — over the same `vendor` + `packages` scope.
- All `yarn …` verbs across CI, lefthook hooks, `package.json` scripts, and docs become `pnpm …` / `pnpm run …`. `yarn.lock``pnpm-lock.yaml` (lockfile v9). `.gitignore` swaps `.yarn/` for `.pnpm-store/`. Vendored READMEs (e.g. `vendor/cordis/README.md`) keep their upstream `yarn` examples untouched per the Vendoring Policy.
## Alternatives considered

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@@ -44,13 +44,11 @@ The durability requirement was specific: the doc should show the **literal** cur
- **A compiled `_Check` assignability assertion** instead of the verbatim source match — rejected because byte-equality, not assignability, is the property we want: a renamed field with the same type would pass assignability.
- **Provenance as directive comments in the prose** — rejected for the central manifest, whose enforced 1:1 correspondence means a block can never be silently unchecked and an entry can never rot.
## Process
## Verification lesson
The design was driven entirely by a one-question-at-a-time grilling that walked the scoping decision tree through concrete examples (`BashExecRequest`, `ToolSchema`, `ToolDefinition`, the schema DSL, the presentation types, the session/persistence split) before committing to the spine-vs-seam rule — the rule was the *output* of the examples, not an a-priori axiom. The implementation landed as four commits mirroring the structure of the work: the gate (`e97f94b`), the catalog (`7e33c7b`), the maintenance-guard updates (`53e01a0`), and a review-fix commit (`6da7a0f`).
The spine-vs-seam rule was tested against `BashExecRequest`, tool schemas and definitions, the schema DSL, presentation types, and the session/persistence split before adoption.
That last commit is why the process is worth recording: an independent Codex review (gpt-5.5:xhigh) found a real **scan-gap bug**`verify-type-equiv` only scanned the docs the manifest named, so a type-equiv block added to an *unmanifested* doc was silently skipped, defeating the 1:1 guarantee in one direction. The fix scans every doc in the markdown scope and reports an unmanifested block as an orphan. The same review corrected a `SessionPersistence` surface-listing prose error (`has`/`delete`) and the `doc-sync` command summary. The bug is the point: a drift gate that silently skips part of its input is worse than no gate, and only an adversarial reader caught it.
This decision shipped in #71 **without** an RFC at the time — the judgment was that the `ts type-equiv` convention was small enough to document in `development.md`. This RFC is the retroactive record: the spine-vs-seam scoping rule and the verbatim-match-over-assignability choice are exactly the kind of "why was it done this way?" decisions a future maintainer would otherwise re-litigate, and its sibling catalog ([generated cordis events + services](2026-06-20-generated-cordis-catalog.md)) does carry an RFC, so the pair should be documented symmetrically.
`verify-type-equiv` must scan the complete Markdown scope, not only manifest-named documents. Otherwise an unmanifested `type-equiv` block escapes the claimed one-to-one check. The gate therefore reports such blocks as orphans. This RFC records that fail-closed scan rule together with the spine-vs-seam and verbatim-match decisions; the generated Cordis catalog has the symmetric design record in [its RFC](2026-06-20-generated-cordis-catalog.md).
## Consequences

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@@ -12,7 +12,7 @@ This is the wiring-axis complement to the [core-data-structures catalog](../../.
Generate the catalog from source instead of hand-maintaining a table and verifying a subset.
`scripts/gen-cordis-catalog.ts` walks the `interface Events` and `interface Context` declarations (plus the service classes) with the TypeScript compiler API and emits two sibling pages: `docs/cordis-catalog/events.md` (events grouped by scope, each rendered as signature + mode badge + its source JSDoc, plus the dispatch-mode legend) and `docs/cordis-catalog/services.md` (each `ctx.<key>` with its public method signatures + class JSDoc). The two axes are separate documents — a reader is either finding what to listen to or what to call, and each page scans and deep-links as its own reference instead of one long combined scroll. It mirrors the `gen-module-graph` pattern exactly: `--write` regenerates both, `--check` fails if either committed file is stale, output is deterministic (sorted), and the files are build artifacts that are never hand-edited. `verify-cordis-catalog` (the `--check`) runs inside `doc-sync`, so the freshness gate fires in the same lefthook pre-push and CI paths as every other doc gate.
`scripts/gen-cordis-catalog.ts` uses the TypeScript compiler API to emit separate event and service references from declarations and source JSDoc. Events include dispatch modes; services include public signatures. Deterministic `--write` and `--check` modes make both pages generated artifacts, with freshness enforced by `doc-sync`.
Pure generation is correct here because the codebase is disciplined enough that the AST is the whole truth: every event/service name is a string literal that round-trips to a static declaration — there are no dynamically-named events and no runtime-only services. So a generated doc cannot be wrong, and it closes the undocumented-event gap structurally (generation enumerates source rather than checking a hand-written subset).

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@@ -2,5 +2,5 @@
# side as of the last confirmed-consistent state. Both languages carry equal authority;
# after editing either side, bring the other along and re-record with:
# pnpm run verify-translation-pairing --write
2026-07-02-bilingual-docs-and-pairing-gate.md: 8731fef46b16cfa20d223575c70774cff780a6aa
2026-07-02-bilingual-docs-and-pairing-gate.zh.md: ce2589498ab16cf5ca2f5cdb3f58d031aeb8298f
2026-07-02-bilingual-docs-and-pairing-gate.md: 68c0f3bbc0472b0c96f9d64fc6b1b24ac7008795
2026-07-02-bilingual-docs-and-pairing-gate.zh.md: 2cf8f9b9c17d8a521d8674833e909b34f315cfe0

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@@ -12,7 +12,7 @@ This repo's README and docs tree are read by people and agents inside and outsid
- **Paired sibling files with equal authority.** A documentation pair is three sibling files: English `foo.md`, Chinese `foo.zh.md`, and a consistency record `foo.i18n.yaml`. Neither language is canonical — a document may be authored and reviewed Chinese-first and translated to English afterwards, or the reverse; what binds the pair is that both sides must say the same thing, and pairs merge whole (both languages plus the record, never one alone). Policy: [docs/i18n/README.md](../../../i18n/README.md); translation rules: [docs/i18n/translation-rules.md](../../../i18n/translation-rules.md); terminology source of truth: [docs/i18n/terminology.md](../../../i18n/terminology.md).
- **A sidecar record of both blob hashes makes consistency checkable.** `foo.i18n.yaml` holds the full git blob hash of each side as of the last confirmed-consistent state. An edit to either side without re-confirming the pair is then mechanically detectable as a pure content comparison — no history lookup — and the hashes are computable for files edited in the same PR, which a commit-hash record is not. Re-recording (`verify-translation-pairing --write`) produces a reviewable yaml diff: confirming consistency is an explicit, visible act in the PR.
- **`verify-translation-pairing` joins `doc-sync`.** The gate ([scripts/verify-translation-pairing.ts](../../../../scripts/verify-translation-pairing.ts)) enforces: required pairs exist, every existing pair is complete (all three files) and consistent (both hashes match, switcher links both ways, structural signatures identical), and excluded (generated or bilingual-by-construction) files stay unpaired. The `required` list in [scripts/translation-pairing.manifest.json](../../../../scripts/translation-pairing.manifest.json) is a ratchet: each merged translation batch adds its files, so coverage only grows.
- **`verify-translation-pairing` joins `doc-sync`.** The gate ([scripts/verify-translation-pairing.ts](../../../../scripts/verify-translation-pairing.ts)) enforces: required pairs exist, every existing pair is complete (all three files) and consistent (both hashes match, switcher links both ways, structural signatures identical), excluded (generated or bilingual-by-construction) files stay unpaired, and date-named documents on or after the manifest's `requiredSince` cutoff have complete pairs. The `required` list in [scripts/translation-pairing.manifest.json](../../../../scripts/translation-pairing.manifest.json) is a ratchet: each merged translation batch adds its files, so coverage only grows.
- **Translation is agent work with human review.** The committed workflow is [.agents/skills/dsh-translate-docs](../../../../.agents/skills/dsh-translate-docs/SKILL.md), following the same pattern as [dsh-code-review](../../../../.agents/skills/dsh-code-review/SKILL.md): the skill carries the workflow and defers to the docs as sources of truth.
## Alternatives considered
@@ -34,5 +34,5 @@ Paired sibling files with locale suffixes are the dominant Chinese big-tech conv
- Every pair adds a third file to the tree. The record is machine-written (`--write`), so the cost is directory noise, not maintenance effort; in exchange, "who confirmed these consistent, and when" is answerable from git blame on the yaml.
- When the two sides disagree, no mechanical rule picks a winner — the PR review does. That is the price of equal authority, accepted deliberately: the alternative (a canonical language) forbids Chinese-first authoring.
- Generated docs (`cordis-catalog/`, `tool-catalog/`, `module-graph.md`) are excluded for now; the planned follow-up is to teach their generators to emit Chinese alongside English, at which point they leave the exclusion list.
- Rollout is incremental by design: documents outside `required` are visible backlog (`--list`), not red CI, so pairs land in reviewable batches without a big-bang PR.
- Rollout is incremental by design: documents outside `required` are visible backlog (`--list`), not red CI, so pairs land in reviewable batches without a big-bang PR. A date-named document dated on or after the manifest's `requiredSince` cutoff merges bilingual or not at all, so new date-named RFCs do not enlarge that backlog.
- The recorded hashes double as the update tool (`git cat-file -p <hash>` recovers either side's last-confirmed text for a minimal diff-based update), so re-translation of whole files is never forced by the mechanism.

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@@ -1,4 +1,4 @@
# RFC: 通过配对兄弟文件与配对门禁实现双语文档
# RFC通过配对兄弟文件与配对门禁实现双语文档
Status: implemented
@@ -6,33 +6,33 @@ Status: implemented
## 问题
本仓库的 README 与 docs 目录树会被公司内外的人和 agent智能体以中英两种语言阅读。没有机制纯靠手工维护第二语言,正是译文腐烂的方式:一侧续演进,另一侧默默地说谎,而没有门禁会注意到。对这类不变式,本仓库一贯的答案是把它编码机械检查(见[质量门禁](2026-06-11-quality-gates.md)与 [doc-sync 强制](2026-06-11-doc-sync-enforcement.md)),因此双语政策随附一道门禁一起交付。
本仓库的 README 与 docs 目录树会被公司内外的人和 agent智能体以中英两种语言阅读。没有机制的情况下纯靠手工维护第二语言,正是译文腐烂的根源:一侧续演进,另一侧默默失实,而没有门禁会注意到。对这类不变式,本仓库一贯的做法是将其编码机械检查(见[质量门禁](2026-06-11-quality-gates.md)与 [doc-sync 强制](2026-06-11-doc-sync-enforcement.md)),因此双语政策随附一道门禁一起交付。
## 决策
- **配对兄弟文件,两种语言同权。**一对文档三个兄弟文件:英文 `foo.md`、中文 `foo.zh.md`一份一致性记录 `foo.i18n.yaml`。没有哪种语言是正典——一篇文档可以先用中文撰写和评审、之后再译成英文,反之亦可;约束这对文件的是两侧必须说同样的话,且配对整体合(两种语言加记录,绝不单独落一侧)。政策见 [docs/i18n/README.md](../../../i18n/README.md);翻译规则见 [docs/i18n/translation-rules.md](../../../i18n/translation-rules.md);术语真源见 [docs/i18n/terminology.md](../../../i18n/terminology.md)。
- **旁挂记录两侧 blob hash使一致性可检查。**`foo.i18n.yaml` 保存两侧文件在上一次确认一致状态下各自的完整 git blob hash。此后改了任一侧而重新确认配对,都能被机械检测出来——纯内容比较无需查询历史——而且同一个 PR改动的文件也能算出 hashcommit hash 式的记录做不到这一点。重新记录(`verify-translation-pairing --write`)产生一份可评审的 yaml diff确认一致在 PR 是一个显式、可见的动作。
- **`verify-translation-pairing` 加入 `doc-sync`。**门禁([scripts/verify-translation-pairing.ts](../../../../scripts/verify-translation-pairing.ts)强制执行required 的配对存在;任何已存在的配对完整(三个文件齐全)且一致(两个 hash 匹配、切换行双向互链、结构签名一致);被排除的文件(生成物或本身即双语的)保持不配对。[scripts/translation-pairing.manifest.json](../../../../scripts/translation-pairing.manifest.json) 中的 `required` 清单是一个棘轮:每个合的翻译批次自己的文件加进去,覆盖面只增不减。
- **翻译是 agent 的工作,由人评审。**进仓的工作流是 [.agents/skills/dsh-translate-docs](../../../../.agents/skills/dsh-translate-docs/SKILL.md),与 [dsh-code-review](../../../../.agents/skills/dsh-code-review/SKILL.md) 同一模式skill 承载工作流,并把真源让给文档
- **配对兄弟文件,两种语言同权。** 一对文档三个兄弟文件组成:英文 `foo.md`、中文 `foo.zh.md`以及一份一致性记录 `foo.i18n.yaml`。没有哪种语言是正典一篇文档可以先用中文撰写和评审、之后再译成英文,反之亦可;约束配对的是两侧必须表达相同的内容,且配对整体合(两种语言加记录,绝不单独落一侧)。政策见 [docs/i18n/README.md](../../../i18n/README.md);翻译规则见 [docs/i18n/translation-rules.md](../../../i18n/translation-rules.md);术语真源见 [docs/i18n/terminology.md](../../../i18n/terminology.md)。
- **伴随记录保存两侧 blob hash使一致性可检查。** `foo.i18n.yaml` 保存两侧文件在上一次确认一致各自的完整 git blob hash。此后改了任一侧而重新确认配对,都能被机械检测出来纯内容比较无需查询历史而且同一个 PRPull Request改动的文件也能算出 hashcommit hash 式的记录做不到这一点。重新记录(`verify-translation-pairing --write`产生一份可评审的 yaml diff确认一致在 PR 是一个显式、可见的动作。
- **`verify-translation-pairing` 加入 `doc-sync`。** 门禁([scripts/verify-translation-pairing.ts](../../../../scripts/verify-translation-pairing.ts))强制执行以下规则required 的配对必须存在;任何已存在的配对必须完整(三个文件齐全)且一致(两个 hash 匹配、切换行双向互链、结构签名一致);被排除的文件(生成物或本身即双语的)不得配对;凡文件名以日期开头且日期不早于 manifest元数据清单`requiredSince` 分界日期的文档,也必须有完整配对。[scripts/translation-pairing.manifest.json](../../../../scripts/translation-pairing.manifest.json) 中的 `required` 清单只进不退:每个合的翻译批次自己的文件加入其中,覆盖面只增不减。
- **翻译是 agent 的工作,由人评审。** 仓库内置的工作流是 [.agents/skills/dsh-translate-docs](../../../../.agents/skills/dsh-translate-docs/SKILL.md),与 [dsh-code-review](../../../../.agents/skills/dsh-code-review/SKILL.md) 模式相同skill(技能)承载工作流,并将文档作为真源
## 曾考虑的替代方案
- **英文为正典源、指纹放在译文内**——本 RFC 最初提出的设计:`.zh.md` 文件携带一条 HTML 注释记录英文源的 blob hash翻译只沿 EN → ZH 单向流动。评审中修订:团队需要中文先行的撰写方式(先写、先审中文 RFC再译英文两种语言同权而单向正典模型无法表达这一点。覆盖**两侧**的旁挂记录取代了文件内的单向指纹blob hash 的机制原样保留
- **语言目录(`docs/en/` + `docs/zh/`Kubernetes/ECharts 模式)**——否决本仓库没有 locale 映射到路由的文档站框架,挪动每个英文文件会搅动所有既有交叉引用`verify-md-links`/`verify-doc-refs` 将需要路径映射逻辑而不是原样工作。
- **独立翻译仓库PingCAP `docs`/`docs-cn` 模式)**——否决适合有独立发布节奏的文档产品,对 monorepo 自的文档而言过重;还会把译文置于本仓库门禁不到的地方。
- **中英混排单文件(一个文件、两种语言)**——否决每个 diff 都翻倍,破坏一段一行约定的 diff 工效,且局部不一致不可见。
- **Commit hash 式记录MDN `l10n.sourceCommit` 模式)**——否决,改用 blob hash同一个 PR 内的改动还没有 commit hashMDN 模式无法表达「与本 PR 引入的状态一致」,且校验它需要 git 历史而非文件内容。
- **比较配对两侧的 git 时间戳(无记录)**——否决纯格式化的改动会误报,一次无关改动之后提交的另一侧会漏报;只有内容同一性这个信号与门禁的承诺名实相符。
- **英文为正典源、指纹放在译文内**本 RFC 最初提出的设计:`.zh.md` 文件携带一条 HTML 注释记录英文源的 blob hash翻译只沿 EN → ZH 单向流动。评审中修订:团队需要中文先行的撰写方式(先写、先审中文 RFC再译英文两种语言同权而单向正典模型无法表达这一点。覆盖**两侧**的伴随记录取代了文件内的单向指纹blob hash 的机制本身保持不变
- **语言目录(`docs/en/` + `docs/zh/`Kubernetes/ECharts 模式)**否决本仓库没有 locale 映射到路由的文档站框架;如果移动所有英文文件所有既有交叉引用都要随之修改;`verify-md-links`/`verify-doc-refs` 将需要路径映射逻辑,而非原样工作。
- **独立翻译仓库PingCAP `docs`/`docs-cn` 模式)**否决适合有独立发布节奏的文档产品,对 monorepo 自的文档而言过重;还会把译文置于本仓库门禁触及不到的地方。
- **中英混排单文件(一个文件、两种语言)**否决每个 diff 都翻倍,破坏一段一行约定的 diff 易读性,且局部不一致不可见。
- **Commit hash 式记录MDN `l10n.sourceCommit` 模式)**否决,改用 blob hash同一个 PR 内的改动还没有 commit hashMDN 模式无法表达「与本 PR 引入的状态一致」,且校验它需要 git 历史而非文件内容。
- **比较配对两侧的 git 时间戳(无记录)**否决纯格式化的改动会误报,一次无关改动之后提交的对侧文件会漏报;只有内容同一性这个信号与门禁的承诺名实相符。
## 业界先例
带语言后缀的配对兄弟文件是中国大厂的主流约定ant-design 的 `index.zh-CN.md`/`index.en-US.md`arco-design 的 `README.zh-CN.md` 加顶部切换行Apache ShardingSphere 的 387 对 `.cn.md`/`.en.md`——但这些仓库都没有在 CI **强制**配对或一致性;约定纯靠评审维系。一致性自动化存在于中国MDN 的 `l10n.sourceCommit` front-matter 指纹、Vue 的 Ryu-Cho action监视上游 commit为陈旧译文自动开 issue/PR、Kubernetes 的本地化漂移脚本、微软 Azure co-op-translatorCI 中由源 hash 驱动的 LLM 重译)。本设计两者结合:中文生态的文件布局,加 hash 对门禁,再加一个仓 agent skill(技能)替代 bot 服务。
带语言后缀的配对兄弟文件是中国大厂的主流约定ant-design 的 `index.zh-CN.md`/`index.en-US.md`arco-design 的 `README.zh-CN.md` 加顶部切换行Apache ShardingSphere 的 387 对 `.cn.md`/`.en.md`但这些仓库都没有在 CI **强制**配对或一致性检查;约定纯靠评审维系。一致性自动化存在于中国MDN 的 `l10n.sourceCommit` front-matter 指纹、Vue 的 Ryu-Cho action监视上游 commit为陈旧译文自动开 issue/PR、Kubernetes 的本地化漂移脚本、微软 Azure co-op-translatorCI 中由源 hash 驱动的 LLM 重译)。本设计两者结合:中文生态的文件布局,加 hash 对门禁,再加一个仓库内置的 agent skill 替代 bot 服务。
## 后果
- 修改已配对文档的任一侧,同一个 PR 就有义务更新另一侧并重新记录配对——门禁 doc-sync 规则双语化,不变式由 CI而非评审者的记忆承载。
- 每个配对给目录树多添一个文件。记录由机器写入(`--write`),代价是目录噪音而非维护负担;换来的是「谁在何时确认过这对一致」可以从 yaml 的 git blame 直接回答。
- 两侧说法冲突时,没有机械规则裁决谁赢——由 PR 评审裁决。这是同权的代价,是有意接受的:另一个选项(正典语言)禁止中文先行撰写。
- 生成文档(`cordis-catalog/``tool-catalog/``module-graph.md`)暂被排除;计划中的后续工作是让它们的生成器在输出英文的同时输出中文,届时移出排除清单。
- 推进天然是渐进的:`required` 之外的文档是可见的 backlog`--list`不是红的 CI因此配对按可评审的批次落地,无需一个巨型 PR。
- 记录的 hash 兼作更新工具(`git cat-file -p <hash>` 能还原任一侧上次确认的文本,用于基于 diff 的最小更新),所以这套机制从不强迫整篇重译。
- 修改已配对文档的任一侧,同一个 PR 就有义务更新侧并重新记录配对门禁 doc-sync 规则双语化,不变式由 CI而非评审者的记忆承载。
- 每个配对给目录树多添一个文件。记录由机器写入(`--write`),代价是目录噪音而非维护负担;换来的是「谁在何时确认过这对文档一致」可以从 yaml 的 git blame 直接回答。
- 两侧说法冲突时,没有机械规则裁决谁赢由 PR 评审裁决。这是同权的代价,是有意接受的:另一个选项(正典语言)禁止中文先行撰写。
- 生成文档(`cordis-catalog/``tool-catalog/``module-graph.md`)暂被排除;计划中的后续工作是让生成器在输出英文的同时输出中文,届时将这些文件移出排除清单。
- 推进天然是渐进的:`required` 之外的文档是可见的 backlog待翻清单,`--list`而非红色的 CI因此配对按可评审的批次落地,无需一个巨型 PR。凡文件名以日期开头且日期不早于 manifest 中 `requiredSince` 分界日期的文档,都必须配齐双语文件,因此新建的日期命名 RFC 不会增加这份 backlog。
- 记录的 hash 兼作更新工具(`git cat-file -p <hash>` 能还原任一侧上次确认的文本,用于基于 diff 的最小更新),因此这套机制从不强迫整篇重译。

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@@ -4,7 +4,7 @@ Status: implemented
## Problem
A reader — a plugin author, a prompt engineer, someone auditing what the agent can do — has no single place that lists the model-facing tools the harness ships. The `name` / `description` / JSON-Schema `parameters` a tool contributes are what the model actually receives (via `ctx.systemPrompt.tools()` off `ctx.tools.schemas()`), but they are scattered across each `defineTool` call in each `packages/*/tool-*` package, buried in string concatenation and runtime spreads. The cordis [events](../../../cordis-catalog/events.md) & [services](../../../cordis-catalog/services.md) catalogs ([their RFC](2026-06-20-generated-cordis-catalog.md)) document the *wiring* a plugin works against and the [core-data-structures catalog](../../../core-data-structures/core.md) documents the *vocabulary* those signatures move — but neither documents the *tools* the agent is offered. This RFC adds that third reference surface, `docs/tool-catalog.md`, and a freshness gate so it cannot drift.
The repository had no single reference for the names, descriptions, and JSON Schemas actually exposed to the model. Source declarations are scattered and runtime-composed, while the existing Cordis and data-structure catalogs cover wiring and vocabulary rather than tools.
## Decision
@@ -27,13 +27,13 @@ Booting has a cost the AST pass did not: there is no source declaration set to e
### A hand-maintained boot manifest is the irreducible policy
The boot manifest (`TOOL_PACKAGES`) is a hand-written list — in tension with the proposed [Discover package inventories instead of maintaining static lists](../../proposed/process/2026-06-20-discover-package-inventory.md). The tension is deliberate and resolved as follows: the *inventory* is discovered (the glob guard means no one maintains "the list of tool packages" — the filesystem is the source of truth, and drift fails the gate), but the *boot recipe* per package — which seams to plug (`bash-local` for `ctx.bash`, `subagent` + `subagent-mock` for `ctx.subagents`) and with what config (`{ provider: 'mock' }`) — is genuine policy that no layout fact encodes. Per that RFC's own "what we give up" ("stay boring: read manifests, filter on explicit fields, print the resolved list, and fail loud"), a recipe closure is the boring, explicit form; inferring seam wiring from injects would be the "too clever" path it warns against. So: discovered inventory, hand-written recipe, gate on completeness.
The filesystem discovers the tool-package inventory and the completeness guard rejects omissions. `TOOL_PACKAGES` still owns an explicit boot recipe for each package because required seam implementations and config are policy, not facts that can be inferred safely from layout or injection names.
### Scope
Shipped product tool PACKAGES under `packages/*/tool-*`, each booted with its default config: `dsh-tool-bash` (`bash`, `bash_output`, `bash_kill`), `dsh-tool-todo` (`todo_write`), `dsh-tool-subagent` (`subagent`). The `examples/` demo tools (`echo`) are excluded, matching the cordis catalog's packages-only scope — a demo tool is not part of the product surface a reader is cataloguing.
Shipped product tool packages under `packages/*/tool-*`, each booted with its default config, including `dsh-tool-bash` (`bash`), `dsh-tool-tasks` (`task_output`, `task_list`, `task_kill`), and `dsh-tool-subagent` (`subagent`). Example-only tools are excluded.
The unit is the PACKAGE, not the deployed tool instance. A package's registered tool name can be a load-time config — `tool-subagent`'s `toolName` — so the same package surfaces as `subagent` (spawn backend) AND `subagent_fork` (fork backend) in the shipped `coding-agent` / `acp-agent` configs, with an identical schema. The generator boots each package once at its default and records such shipped aliases in a per-package note, rather than enumerating every deployment permutation. Cataloguing at the package level keeps the source of truth the package (what a plugin author reads) and avoids leaking example-app `cordis.yml` config into a packages-scoped generator; the note keeps the doc honest about the names a reader will actually see the model receive. The design deliberately does not attempt to catalog "every configured tool instance across every leaf config" — that is a deployment inventory, a different (and unbounded) surface.
The catalog unit is a package, not every configured tool instance. Each package boots once with default config; load-time aliases such as `subagent_fork` are noted without enumerating every deployment permutation. A deployment inventory is a separate, unbounded surface.
### A plain `json` fence

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@@ -4,7 +4,7 @@ Status: implemented
## Problem
The [generated cordis catalog](2026-06-20-generated-cordis-catalog.md) already walks every harness `interface Events` member and every `ctx.<key>` service class with the TypeScript compiler API, and already hard-errors on a missing `@mode` tag — a forcing function that made dispatch modes impossible to leave undocumented. Nothing equivalent guarded the rest of the JSDoc: a service method could ship with no doc at all, and no event or method documented its parameters or return value individually. A survey at adoption found 5 public service methods with no JSDoc and roughly 139 missing `@param`/`@returns` entries across 15 files — on the product API spine (`ctx.bash`, `ctx.fs`, `ctx.sessions`, …) and the cross-plugin event payload contracts, exactly the surface where "what does this argument mean" is the question a plugin author asks the IDE.
The generated Cordis catalog enforced event dispatch modes but not complete service and event contracts. Methods could lack descriptions, and parameters or returns could be undocumented on the cross-plugin API surface where IDE guidance matters most.
The AGENTS.md rule ("every export has a JSDoc explaining semantics") is prose-checkable only by review; the repo's stated preference is to encode invariants in mechanical gates. The scope "cordis service functions and events" has a precise machine definition that only the catalog generator knows: events are the `interface Events` members inside `declare module 'cordis'`, and the service surface is the public methods of the class each `interface Context` key names. An ESLint rule cannot see that mapping; the generator computes it on every run.

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@@ -4,7 +4,7 @@ Status: implemented
## Problem
The repo's standing docs accrete. Root `AGENTS.md` reached 8,130 words through 50 commits in two and a half weeks — each PR appending its own lesson, none displacing anything — until the same rule was stated two or three times inside one file (the pushed-branch rewrite ban ~600 words across two sections; the with-key e2e policy ~400 words across two), an incident already recorded in [postmortem 0001](../../../postmortem/0001-acp-default-export-drops-inject.md) was retold inline at ~750 words, and the per-package one-liner map existed in five places. [architecture.md](../../../architecture.md) grew the same way: paragraph walls re-narrating RFCs it already links, plus implementation-status annotations that were stale the week after they were written. The writing rules that forbid this (document current state, never history) predate the drift and sat in the very file violating them — prose rules alone do not hold against accretion pressure. The repo's standing answer to an invariant of this kind is a mechanical check ([quality gates](2026-06-11-quality-gates.md), [doc-sync enforcement](2026-06-11-doc-sync-enforcement.md)).
Standing docs accumulated repeated rules, retold incidents, duplicated package maps, and stale RFC summaries despite existing writing guidance. Because review alone did not prevent that growth, the repository needed a mechanical budget alongside its documentation taxonomy.
## Decision
@@ -24,11 +24,3 @@ The repo's standing docs accrete. Root `AGENTS.md` reached 8,130 words through 5
- Adding to a budgeted doc now requires displacement: relocate the addition to its taxonomy home with a pointer, or condense existing prose to pay for it. Growth without pruning fails CI.
- The bring-under-target rewrites land as stacked follow-ups that ratchet the manifest down as they merge; until each lands, its doc's frozen ceiling only prevents further growth.
- Word count is a crude proxy accepted deliberately: it cannot judge quality, but it forces the relocation decision at exactly the moment content is being added, which is when the author has the context to place it correctly.
## Deferred work
The first audit cycle under the standard, in rough priority order (evidence gathered in the survey that motivated this RFC):
- Package README trims where generated catalogs or JSDoc are restated or history is narrated: `packages/ui/acp`, `packages/core/tools`, `packages/bash/tool-bash`, `packages/core/session`, `packages/compact/compact-basic`, `packages/session-persistence/session-persistence`.
- `docs/core-data-structures/core.md`: drop the JSDoc walls from the `Agent`/`GenerateOptions` type-equiv pastes per that page's own stated rule.
- [Postmortem 0001](../../../postmortem/0001-acp-default-export-drops-inject.md): merge the overlapping Executive summary and Summary sections.

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@@ -4,13 +4,13 @@ Status: implemented
## Problem
The session event log is the harness's on-disk contract: every `SessionEventMap` member is a record a persistence backend writes verbatim and a replay reconstructs from, and adding one that breaks the durability rules is a breaking change to the on-disk format. Yet the vocabulary had no single reference. The declarations are split across three files — the owning interface in `@deepseek-ai/dsh-session` plus declaration merges in `@deepseek-ai/dsh-compact` and `@deepseek-ai/dsh-hook-protocol` — and the doc surfaces covered it with hand-copies: a `hook/*` payload table in [session.md](../../../core-data-structures/session.md), a `compact/*` payload table in the compact README, payload bullets in the hook-protocol README, and a name-list in the session README. The name-list's merge note had already drifted (it named the compaction merge and omitted the hook merge entirely), and nothing could catch the next merge going undocumented: a hand-copy only checks the names someone already wrote down. This is the same gap the [cordis catalog](2026-06-20-generated-cordis-catalog.md) closed for bus events and the [tool catalog](2026-07-02-tool-schema-catalog.md) closed for model-facing tools — and log events are covered by neither: a `SessionEventMap` member is not a cordis `Events` declaration (it reaches listeners via the single `session/event` emit), so it has no cordis-catalog row by design.
`SessionEventMap` is the on-disk vocabulary, but its declarations are split across the owning session package and declaration merges. The generated persistence catalog is the single reference for every event and payload; hand-maintained tables drift and are removed. These records are not Cordis events—observers receive them through the single `session/event` bus event—so the Cordis catalog cannot cover them. The generator discovers all declarations and the doc-sync freshness gate rejects omissions or stale output.
## Decision
Generate `docs/persistence-catalog.md` from source, with a freshness gate, as the fourth reference surface: the *records* a persisted session log can contain, complementing the cordis catalog (wiring), core-data-structures (vocabulary), and the tool catalog (tools).
`scripts/gen-persistence-catalog.ts` is a pure TypeScript-AST pass, like `gen-cordis-catalog.ts` — log events ARE statically knowable: every member is a string-literal-named property with a static type annotation, so the AST is the whole truth. The walk collects every `interface SessionEventMap` declaration under `packages/*/*/src` — the owning top-level interface and every `declare module '@deepseek-ai/dsh-session'` merge — so a brand-new event, core or merged, appears in the next regenerate and an un-regenerated file fails `--check` (`verify-persistence-catalog`, a `doc-sync` member, so pre-push and CI both run it). Each entry renders the member's JSDoc prose, its payload (printed through the TypeScript printer, so a newline-separated multi-line type literal still yields a valid one-line fragment), a surface badge, cross-links into core-data-structures, and the declaration's source pointer, grouped by scope.
`gen-persistence-catalog.ts` scans every owning and declaration-merged `SessionEventMap` with the TypeScript AST. It renders source JSDoc, payload type, derived surface badge, reference links, and source location. The doc-sync freshness check rejects a vocabulary change whose catalog was not regenerated.
Specific choices:

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@@ -4,7 +4,7 @@ Status: implemented
## Problem
The tree's layout is uniform — [the classification scheme](2026-06-20-rfc-classification.md) path-encodes lifecycle and class and gates both — but the file insides never were. The corpus the format decision faced had two H1 spellings; some twenty-seven `Status:` line spellings once free-text rejection reasons are collapsed — bare enums, dated parentheticals duplicating what the filename and git already carry — plus three English files (and the zh counterpart of one of them) with no status at all; two body genres side by side (ADR-style `Context`/`Decision`/`Consequences` beside proposal-style `Problem`/`Proposal`/`Risks`), so every new RFC guessed its shape from whichever neighbor its author opened; thirty-nine files carrying a debt comment that flagged them as "legacy ADR/RFC body format" awaiting a unified template that was never actually defined; and nineteen implemented RFCs still carrying thirty occurrences of the proposal-era headings (`Acceptance criteria`, `Plan`, `Migration plan`, `Proposal`) that the [documentation standard's slop checklist](../../../AGENTS.md) outlaws for `implemented/` — outlawed, but enforced by nothing, so the `proposed/``implemented/` move could silently skip the rewrite [implemented/AGENTS.md](../AGENTS.md) requires.
RFC paths encoded lifecycle and class, but file contents still mixed headings, status formats, ADR and proposal templates, and proposal-era sections in implemented records. Authors copied whichever neighbor they found, and lifecycle moves could skip the required rewrite because no gate enforced an in-file contract.
## Decision

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@@ -22,7 +22,7 @@ The contract by declaration kind:
Three exemption families keep the gate from demanding boilerplate, in the spirit of the cordis gate's `this`/`next` exemptions (documenting an exempt name anyway is allowed; only absence goes unchecked):
- **Heritage members.** A class member whose name exists on an `extends`/`implements` heritage type is exempt: the seam declaration is the doc's one home, and the IDE inherits it on hover — re-documenting every `LocalBashExecutor.run` invites drift. The exemption stops where the override grows surface the base never documented: a protected-only base member does not exempt a public override, parameters the base never names keep their `@param` duty (an underscore-prefixed rename of a base parameter — the deliberately-unused marker — is the same parameter), and a concrete result above a void base return keeps its `@returns` duty (an unannotated override's inferred return is classified by the checker, so a faithful void override needs no boilerplate annotation). Heritage lookups and that one return classification are the walk's only TYPE CHECKER questions (heritage types live across package boundaries, resolved through the repo `paths` map); everything else stays pure AST, and the annotated-return requirement is kept for symmetry with the cordis gate (it bound nothing at adoption — every exported function was already annotated).
- **Heritage members.** Overrides inherit documentation from their base declaration. New public surface still requires docs: added parameters, a public override of a protected member, or a concrete return over a void base. Heritage lookup and inferred return classification are the gate's only type-checker work; other checks use the AST.
- **Plugin-protocol slots.** Top-level `name` / `inject` / `reusable` / `Config` consts and the `apply` entry, plus the same slots as statics on a plugin class, are framework protocol: their shape is fixed by cordis, and the module doc comment plus the `interface Config` carry the plugin's real semantics.
- **Constructors**, mirroring the cordis gate: plugin classes are framework-constructed, and the class doc owns the story.

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@@ -4,11 +4,11 @@ Status: implemented
## Problem
The config surface — the exact set of fields a `cordis.yml` entry's `config:` block can set for each plugin, with types, defaults, and semantics — had no reference page. A deployment author assembling a config tree had to open every plugin's source (or trust its README) to learn what is settable. The per-package README `## Config` sections cover parts of it by hand, in formats that diverged package-by-package (a key/default table here, an annotated YAML snippet there) and with no gate tying them to source. Nothing enumerated which packages are loadable at all — plugin vs abstract seam vs plain library — and nothing verified that the runtime schemastery schema and the documented `Config` interface agree, so a schema-validated field could exist with no documentation anywhere.
The repository had no source-backed reference for plugin configuration. Package READMEs documented fields inconsistently, did not enumerate which packages are loadable, and did not verify that runtime schemas agree with declared config types.
## Decision
Generate the catalog from source: `scripts/gen-config-catalog.ts` emits [docs/config-catalog.md](../../../config-catalog.md), one section per configurable package containing the VERBATIM config declaration — the `export interface Config` (or equivalently named type) with its JSDoc, pasted as-is in a ` ```ts config-catalog ` fence — plus a `Requires:` line (the plugin's `inject`), a `Depends on:` line resolving every type name the paste references, and a source pointer. The paste is the plugin's full declared config type: a field the runtime schema deliberately excludes is a runtime-only seam, marked as such by its own JSDoc, not a `cordis.yml`-settable knob. Package-local referenced types are pasted transitively into the same fence; another plugin's config type links to that plugin's section; names in the cordis catalog's shared `LINK_MAP` link to core-data-structures; any other workspace type links to its source; an external type is named with its module. It mirrors the `gen-cordis-catalog` pattern exactly: `--write` regenerates, `--check` (`verify-config-catalog`, inside `doc-sync`) fails if the committed file is stale, output is deterministic, the file is a build artifact never hand-edited.
`scripts/gen-config-catalog.ts` emits [docs/config-catalog.md](../../../config-catalog.md) from each plugin's declared config type and JSDoc, with injection requirements, referenced-type links, and a source pointer. Package-local types are included transitively; workspace and external types are linked or named. Deterministic `--write` and `--check` modes make the committed page a generated artifact.
Pure AST generation is correct here for the same reason it is for the events/services catalog and NOT for the tool catalog: a config type is a static declaration and every schemastery schema in the repo is a static `z.object`/`z.intersect` literal, so the source is the whole truth — nothing about the config surface is runtime-composed.
@@ -17,7 +17,7 @@ Specific choices:
- **The config type is the second-parameter type.** What the catalog documents is the declared type of `apply(ctx, config)` / the service constructor's `(ctx, config)` — the value cordis actually passes — not a `Config` export located by naming convention. This is what makes the walk total: it works for interfaces named `AcpConfig` or `BasicCompactConfig`, for types declared in a sibling file, and for plugins with no validating schema at all.
- **Classification is total.** Every `packages/<group>/<pkg>` entry resolves, mirroring the Loader's `unwrapExports` (`exports.default ?? exports`), to a configurable plugin, a config-free plugin, an abstract seam class, or a library — each rendered in its own section — and an unclassifiable entry hard-errors. A new package cannot be silently undocumented.
- **Per-field JSDoc is enforced.** Every property of a pasted declaration (nested type literals included) needs non-empty JSDoc prose, or generation fails. The paste IS the documentation, so this is the same forcing function the events catalog applies via `@mode`: thin source docs fail the gate rather than yielding a thin catalog.
- **The schema is cross-checked, one-directionally, nested keys included.** When a plugin declares a schemastery schema (`export const Config` / `static Config`), the generator walks it statically — object-literal keys and their nested object/array compositions as key paths (`agents[].id`), chained refinements, and `z.intersect` composition across workspace packages — and every schema-validated key path must be locatable on the declared config type, resolving package-local and workspace-imported types (re-export chains included), intersections, unions, utility wrappers, and indexed access. So the paste cannot hide a loader-accepted field, top-level or nested. The check is presence-only and fails loud only on a definite miss: a path crossing a type the walk cannot enumerate (an external package's type) is skipped rather than mis-reported, and dynamic-key shapes (`z.dict`) or union alternatives contribute no nested paths. The reverse direction is deliberately unchecked: a declared field may be a runtime-only seam the schema excludes (the ACP bridge's test-injected `stream`).
- **Schema keys are checked against the declared type.** The generator resolves nested object and array paths through local and workspace types. Definite missing paths fail; external or dynamic shapes that cannot be enumerated are skipped. The check is intentionally one-way because declared types may contain runtime-only fields excluded from loader config.
- **A dedicated fence.** Pasted declarations use a ` ```ts config-catalog ` info string that `doc-typecheck` skips (a lone declaration referencing imported types is not standalone-compilable), excluded from the opt-out ratio — the same treatment the `cordis-catalog` and `persistence-catalog` fences get.
- **A single file at `docs/config-catalog.md`**, not a one-file directory: the page serves one audience (the `cordis.yml` author) with one axis, unlike `cordis-catalog/`, which holds two sibling pages.

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# RFC: Raise the Node LTS engine floor to 22.19
Status: implemented
## Problem
The Node 22 branch of the root `engines.node` range is a contract for the installed workspace, not only for the runtime APIs the harness source calls directly. It must be no lower than package `engines.node` declarations for dependencies the workspace installs on that branch; otherwise `pnpm install --engine-strict` fails at an advertised LTS version, and non-strict installs run outside a dependency's supported runtime.
## Decision
Set `engines.node` to `^22.19.0 || >=24.0.0` and test the keyless CI compatibility matrix on `['22.19', 24, 26]`. Every matrix leg runs the TypeScript typecheck plus a keyless source-mode worker smoke, so the floor is exercised through both a complete source typecheck and a real unbuilt runtime path. The real-API e2e workflow stays on Node 24 because it exercises API integration rather than the runtime floor.
Two Node features gate the source runtime:
- **`node:sqlite`** — `packages/session-persistence/session-persistence-sqlite` does a top-level `import { DatabaseSync } from 'node:sqlite'`. The module dropped its `--experimental-sqlite` flag requirement at **22.13** (LTS) and **23.4** (Current); before those, importing it throws at load.
- **Native TypeScript type-stripping** — the `packages/examples/stdio-demo/tests/built-bin.e2e.ts` smoke boots the published `lib/bin.js` under plain `node` (no tsx) and loads the example's `.ts` plugins (`mock-llm.ts`, `echo-tool.ts`). Type-stripping is the default from **22.18** (LTS) and **23.6** (Current); before those it needs `--experimental-strip-types`.
Those source features clear on the 22.x line at **22.18**, but the installed Pi adapter dependency raises the advertised LTS floor. `@deepseek-ai/dsh-llm-pi-ai` depends on `@earendil-works/pi-ai@0.79.3`, whose package declares `engines.node >=22.19.0`, so the LTS floor is **22.19**. The 24.x branch remains `>=24.0.0`. The disjoint range excludes Node 23 entirely: Node 23.023.5 still has at least one flagged source feature, and the 23 line is non-LTS/EOL, so advertising `>=23.6` would add a dead release line and a CI leg no deployment should use.
`@types/node` remains pinned to the 22.x line (`^22.20.0`) to match the LTS support line: reaching for a Node 23+/24+/25+ API fails `tsc` on every machine and in the typecheck gate, rather than compiling clean and surviving to a runtime failure only a floor matrix leg could catch. The whole tree typechecks clean against the Node 22 type surface today, so the pin costs nothing.
## Consequences
- The advertised LTS branch no longer undercuts the Pi adapter dependency floor.
- CI proves the Node 22 LTS floor directly with Node 22.19, keeps the Node 24 branch on `node: 24`, and keeps Node 26 for the next even line; each leg typechecks the source graph and launches the unbuilt workflow worker for real.
- The built-bin smoke needs no version-conditional flag: at 22.19 type-stripping is already the default, so the test stays the plain `node lib/bin.js` path it documents.
- A future dependency or source API that raises the runtime floor must move `engines.node`, the compatibility matrix, and this RFC in the same change.
## Alternatives considered
- **Keep `^22.18.0 || >=24.0.0`.** Rejected: it advertises an LTS version lower than the Pi adapter dependency floor. `@earendil-works/pi-ai@0.79.3` requires `>=22.19.0`.
- **Downgrade or pin `@earendil-works/pi-ai` to preserve the 22.18 advertised range.** Rejected: the current Pi adapter dependency is part of the intended workspace, and 22.19 is still inside the Node 22 LTS line.
- **Floor `>=22.13` (the `node:sqlite` boundary) plus `--experimental-strip-types` in the built-bin smoke on 22.1322.17.** Rejected: it adds a version-conditional test flag for one narrow range and dresses up an experimental-flag dependency as first-class support. The Pi adapter dependency already requires a higher LTS floor.
- **Open-ended `>=22.19`.** Rejected: it advertises support for Node 23.023.5, where `node:sqlite` (until 23.4) or type-stripping (until 23.6) is still flagged.
- **Include Node 23.6+ (`^22.19.0 || >=23.6.0`).** Rejected: 23.6+ does run both source features unflagged, but Node 23 is end-of-life; advertising a dead release line adds a range term and a CI leg for a runtime no deployment should use.
- **Matrix `[22, 24, 26]` instead of pinning `22.19`.** Rejected: floating major-version entries drift upward over time and silently stop exercising the declared LTS floor.
- **Keep `@types/node` ahead of the floor (`^25`).** Rejected: types ahead of the runtime floor let a Node 24/25-only API compile clean and fail only at runtime on 22.x. Pinning `@types/node` to the 22.x line turns that into a compile error everywhere.

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@@ -10,15 +10,15 @@ The hard part is the artifact boundary. `publint`, `verify-node-next-types`, and
## Decision
[CI](../../../../.github/workflows/ci.yml) keeps the keyless workflow to a few broad jobs instead of one job per gate. The Node 24 matrix has five lanes: static gates (`pnpm run check:ci:static`), lint (`pnpm run check:ci:lint`), coverage (`pnpm run check:ci:coverage`), snapshot replay (`pnpm run check:ci:snapshot`), and artifact gates (`pnpm run check:ci:artifacts`). The Node 26 compatibility job installs once and runs `pnpm run check:node-compat`.
[CI](../../../../.github/workflows/ci.yml) groups keyless checks into broad primary-runtime lanes plus a compatibility matrix. The workflow file owns the current lane and runtime inventory.
Each lane delegates to [scripts/run-gates.ts](../../../../scripts/run-gates.ts), an in-process scheduler with bounded concurrency (`DSH_GATE_CONCURRENCY`). The static lane fans out constraints, the echo-agent demo smoke, `doc-sync` leaf gates, module-graph freshness, and `knip`; the lint lane runs ESLint with its own Node heap cap and a content-strategy ESLint cache; the coverage lane runs Vitest coverage with bounded file workers (`DSH_COVERAGE_MAX_WORKERS`); the snapshot lane isolates replay; the artifact lane builds once and then fans out the artifact consumers; the Node 26 compatibility job owns the TypeScript typecheck. The scheduler buffers each gate's output and prints a named result block with duration, so independent failures stay attributable inside each broad job log.
Each lane delegates to [scripts/run-gates.ts](../../../../scripts/run-gates.ts), which schedules independent gates with bounded concurrency and prints an attributable result block for each one. Artifact consumers depend on one build within their lane, while compatibility jobs combine typechecking with a real unbuilt worker launch to cover runtime-specific loader behavior.
Generated `.sessions/` logs and `.doc-typecheck-*` temp directories are ignored by lint. The aggregate local CI mode still runs demo smoke after lint, while the split GitHub static lane can run demo smoke directly because lint is isolated in its own lane.
Build output is produced once inside the Node 24 artifact lane. The artifact consumers (`publint`, `verify-node-next-types`, and built-bin smoke) declare a dependency on `build`, so there is no upload/download handoff and no consumer can race ahead of declarations or bundles. The CI coverage reporter is text-only while local coverage keeps the HTML report.
Both CI workflows cache the pnpm store after enabling Corepack. The real-API e2e workflow also uses the shared `vitest.e2e.config.ts` bounded file pool (`DSH_E2E_MAX_WORKERS=14` in CI), so its speedup comes from dependency-cache reuse plus lower-level test-file fan-out instead of a separate GitHub job split.
Both workflows cache the pnpm store. The real-API workflow uses the shared bounded Vitest file pool rather than a separate job per test group.
## Alternatives considered
@@ -36,4 +36,4 @@ The broad-lane split repeats checkout, setup, and install more often than a sing
The split introduces a maintenance obligation: when `package.json` adds or removes a gate that belongs in CI, [scripts/run-gates.ts](../../../../scripts/run-gates.ts) needs the matching leaf. That obligation is intentional because the runner is the parallel execution plan for the same gate vocabulary, not a separate quality policy.
The Node 26 signal is narrower than the primary Node 24 signal. It proves the source graph on the newer runtime without doubling documentation, coverage, publication, snapshot, and smoke checks whose failures are not expected to vary by Node minor version.
The compatibility signal is narrower than the primary Node 24 signal. It proves that the source graph typechecks and that the real unbuilt workflow-worker launch path executes on every advertised runtime line without doubling documentation, coverage, publication, snapshot replay, and unrelated smoke checks whose failures are not expected to vary by Node version.

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@@ -14,9 +14,9 @@ Flattening those members directly into `lefthook.yml` solves the local hook only
[lefthook.yml](../../../../lefthook.yml) keeps one pre-push job named `full check` and runs `pnpm run check:pre-push`. That package script delegates to [scripts/run-gates.ts](../../../../scripts/run-gates.ts), the same bounded scheduler CI uses.
The `pre-push` mode expands into leaf gates for the unit suite, snapshot suite, build, `hygiene` members, `doc-sync` members, and module-graph freshness. The leaf list keeps the same gate vocabulary as the package scripts, including RFC classification and RFC format, while the runner schedules independent checks concurrently and prints one timing/output block per gate.
The `pre-push` mode expands into leaf gates for the unit suite, snapshot suite, build, `hygiene` members, `doc-sync` members, and module-graph freshness. The leaf list keeps the same gate vocabulary as the package scripts, including RFC classification and RFC format, while the runner schedules independent checks with four active top-level workers by default; `DSH_GATE_CONCURRENCY` overrides that bound.
The build gate makes the hook self-contained from a clean worktree. `publint` and `verify-node-next-types` wait for that build output, while source-only gates continue in parallel.
The build gate makes the hook self-contained from a clean worktree. `publint`, `verify-node-next-types`, and the pre-push form of `doc-typecheck` wait for that build output, while source-only gates continue in parallel.
[scripts/publint-all.ts](../../../../scripts/publint-all.ts) discovers the package list from `packages/<group>/<pkg>` and runs `publint` with a worker pool sized from `availableParallelism()`. `DSH_PUBLINT_CONCURRENCY` can cap or raise the worker count for local machines and CI runners with different resource profiles. Results are buffered per package and printed in deterministic package order, so parallel execution does not scramble each package's log block.

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# RFC: A gated Known-Limitations section in every package README
Status: implemented
## Problem
The [documentation standard](../../../AGENTS.md) assigns limitations to package READMEs. Without a shared shape, an omitted section cannot distinguish an audited absence from forgotten documentation, and variant headings prevent a repository-wide search.
## Decision
Every package manifest under `packages/<group>/<pkg>/package.json` has a sibling README with the canonical `## Known Limitations and Deferred Work` section. Its bullets record durable consumer gaps and non-obvious maintainer constraints owned by that package; ordinary cleanup remains in its source TODO or owning RFC. The [`verify-package-readme-limitations` gate](../../../../scripts/verify-package-readme-limitations.ts) derives the package set from manifests, rejects missing READMEs, and requires exactly one canonical h2 with at least one top-level bullet. Near-miss headings such as “Limitations,” “Deferred,” “What is NOT here,” or “Non-goals” fail.
A package with nothing to declare is listed in `NO_LIMITATIONS` and omits the section. Adding a limitation requires removing the entry; renames and removals fail because every entry must name a scanned package.
The gate checks presence, shape, and the allowlist. Review under the documentation and [prose](../../../../.agents/skills/dsh-prose-standard/SKILL.md) standards owns coverage and accuracy. The standing rule lives in [packages/AGENTS.md](../../../../packages/AGENTS.md).
## Alternatives considered
- **Free-form headings** — cannot be searched uniformly and still need near-miss detection.
- **Require an empty section or “None.”** — boilerplate can remain after a package gains a limitation; an allowlist makes absence explicit and reviewable.
- **Impose a word ceiling** — legitimate limitation counts vary, so review governs this unbudgeted README tier.
## Consequences
- New packages declare qualifying limitations or explicitly join the allowlist; missing, drifted, and empty sections fail `doc-sync` locally and in CI.
- The gate adds one dependency-free TypeScript script to `doc-sync`.
- Renaming the enforced heading requires changing the script and every package README together.

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# RFC: Package Model Experience contract
Status: implemented
## Problem
A package README can explain APIs and runtime mechanics without answering the question that dominates an agent harness's behavior and cost: what from this package reaches a model request, under which conditions, and how long those tokens remain. The omission is especially hard to audit in a plugin architecture. A consumer may turn a backend result into a tool message, a policy plugin may replace success with an error, compaction may remove old history, and an agent-scoped registration may change one agent's prompt or schemas while leaving every other agent unchanged. Reading only the nominally model-facing packages therefore misses real context effects, while reading source across every dependency is too expensive for routine review.
## Decision
Every workspace package README with a model-facing or model-adjacent contract ends with the canonical [Model Experience section](../../../cookbook/adding-a-package.md#4-write-the-package-readme), immediately before `## Known Limitations and Deferred Work`; a package on the no-limitations allowlist ends with Model Experience itself. An audited model-agnostic generic package omits the section through `NO_MODEL_EXPERIENCE_SECTION`.
Packages with direct, conditional, capped, lifetime, multi-surface, or auxiliary-model effects use one H3 per context surface. Each names what the relevant model receives and when, then classifies the token effect. Stable package-owned text is quoted exactly: system-prompt prose and other long literals use a nested H4 plus `markdown` fence, while short literals stay inline with named interpolation placeholders. Tool-schema surfaces link their anchored section in the generated [tool catalog](../../../tool-catalog.md) and state only composition or configuration deltas; runtime-only definitions explain why the catalog omits them. Data-dependent and provider-owned text is summarized. Agent-scoped visibility is explicit, and prompt and schema surfaces remain separate when scoping can hide one without the other.
A package with no model-context effect, or one path rendered entirely by another package, uses the verifier's audited one-sentence form: `None, as ` or `Indirectly, through `. Pure transport and keyless test-support packages use the none form when they create no model-bound content. Provider backends use the indirect form even when they cap or filter data, and wiring bundles use it when named children own every effect. These sentences locate the contribution without restating the consumer. Structured sections likewise document only package-owned inputs, transformations, and deltas.
`verify-package-readme-model-experience` discovers package manifests and validates the three classifications, canonical final-section order, required fields, concrete literal evidence, nested verbatim blocks, and anchored tool-catalog links. It runs in `doc-sync` and the parallel gate runner. Review still owns coverage, link relevance, and factual accuracy.
## Alternatives considered
- **Document only packages that register prompts or tools** — rejected because backends, policy plugins, adapters, persistence, scoping, and compaction change the content or lifetime of tokens without owning a model-facing schema.
- **Generate one central context-cost catalog from source** — rejected because an AST can find registrations but cannot infer semantic conditions such as history retention, output truncation, parent-versus-child visibility, or an auxiliary model boundary. The package README is the implementation-local contract; a central copy would add another drift surface.
- **Require numeric token counts** — rejected because exact counts depend on the selected model tokenizer, adapter serialization, configuration, and runtime data. The stable contract is the growth shape: fixed per request, conditional per call, retained, replaced, capped, or zero-direct.
- **Use a three-column table** — rejected because exact source text and conditional result shapes make cells dense and difficult to scan. Repeated subsections give each context surface readable vertical space while preserving the same fields.
- **Allow every zero-impact package to omit the section** — rejected because unconstrained absence is ambiguous between an audited zero and forgotten documentation. Omission is reserved for model-agnostic generic packages named with a reason in the verifier; model-adjacent zero-impact packages keep one explicit sentence.
- **Require the full structured form for audited zero or simple indirect packages** — rejected because it repeats labels around one fact. A gated sentence preserves explicit coverage without the ceremony.
- **Convention without a gate** — rejected because a repo-wide contract must also cover every future package; review memory cannot reliably detect an omitted README section.
## Consequences
A reviewer can start at any model-facing or model-adjacent package and see its contribution to the conversation model, child models, and auxiliary calls without reconstructing the full plugin graph. Token-budget work can distinguish repeated request overhead from data-dependent history, and agent-scoped changes have an explicit documentation checkpoint. Package authors maintain one or more compact context-surface blocks or one classified sentence whenever model-visible behavior changes; audited generic packages carry no irrelevant model boilerplate. The structured fields do not promise provider-exact token counts; measurements remain model- and workload-specific, while the documented growth and visibility contract stays stable.

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# Bilingual-pair consistency record (docs/i18n/README.md): the git blob hash of each
# side as of the last confirmed-consistent state. Both languages carry equal authority;
# after editing either side, bring the other along and re-record with:
# pnpm run verify-translation-pairing --write
2026-07-14-typescript-program-backed-semantic-gates.md: 3e7a76e86d83080ae1a4f91ca97cc9749c90ef29
2026-07-14-typescript-program-backed-semantic-gates.zh.md: 0a13452012e7f6cbd3ad7994845ba1985355c089

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# RFC: TypeScript Program-backed semantic gates
Status: implemented
English | [中文](2026-07-14-typescript-program-backed-semantic-gates.zh.md)
## Problem
Repository gates sometimes need facts that TypeScript syntax does not carry by itself: whether a receiver is a Cordis `Context`, which concrete event names reach a forwarding helper, and whether declaration merging changed an event signature.
The existing gates use TypeScript's single-file syntax model and maintain these facts through naming conventions, handwritten tables, and JSDoc.
The repository needs one semantic source of truth without introducing runtime package cycles, broad fallback heuristics, or machine-readable annotations that restate information already available to TypeScript.
## Decision
Repository gates can combine project-wide type information through `ts.Program` and use `TypeChecker` to extract **strongly typed** facts, reducing their reliance on naming conventions, handwritten tables, and JSDoc metadata.
The repository applies this model to two gates.
### One project model expands the root solution
[`TypeScriptProject`](../../../../scripts/ts-project.ts) parses the root `tsconfig.json`, recursively expands every project reference, and combines the referenced source roots into one no-emit semantic program. A normal program created from the solution config can redirect referenced projects to built declarations; explicit expansion keeps the package `src` files available for AST traversal and symbol identity.
The wrapper owns config diagnostics, semantic compiler options, repository-relative paths, source lookup, and the shared checker. Individual gates do not glob package sources or construct partial programs independently.
### A. Event relations follow receiver and value types
[`gen-doc-graphs`](../../../../scripts/gen-doc-graphs.ts) classifies calls by assignability to the repository's actual `Context`, `AgentEventDispatch`, and Cordis `EventsService` types. Variable names and property spellings do not determine whether a call is an event operation.
Context and agent-dispatch calls contribute only finite string-literal event sets. Direct `EventsService.dispatch()` calls recover the event slot through array literals, constant aliases, conditional branches, and resolved call sites of non-exported local helpers. Generic forwarding parameters are not concrete producers: attribution stays with the call sites that supply a closed event value.
Every declared harness event must have a discovered producer. A missing producer fails generation as dead vocabulary or an unsupported semantic dispatch shape; listener-free extension points remain valid. `internal/dispatch` instrumentation is not treated as a subscription to every event it observes, so the matrix contains direct product listeners rather than manually asserted indirect relationships.
### B. Scoped-event routing generates one typed resolver map
[`gen-scoped-events`](../../../../scripts/gen-scoped-events.ts) scans real `scopeTarget(base, key)` calls to establish the routing-key type for each scoped base. It then finds Cordis `Events` members with `this: Scoped<Base>` and searches every payload parameter plus one public property level for a type identical to that key after removing `null` and `undefined`.
Exactly one match generates a resolver. Multiple matches are ambiguous and fail. Zero matches require `@dshScopeScan unsupported`, which is reserved for events whose routing key intentionally stays outside the payload, such as owner-keyed session events and parent-keyed subagent lifecycle events. The annotation records an unsupported scan; it does not encode an event name, parameter index, property path, or replacement type.
The committed [`scoped-events.generated.ts`](../../../../packages/support/invariants/src/scoped-events.generated.ts) imports every scoped-event owner for its type-side `Events` contributions. Each generated lambda accepts `Parameters<Events[K]>`, and the complete object satisfies a `Record` over the derived `ScopedEventName` union. Ordinary TypeScript compilation therefore checks event existence, parameter position, property access, and scoped-event completeness. The only cast adapts Cordis's runtime `unknown[]` dispatch boundary to the already type-checked resolver.
The invariants plugin consumes this generated runtime map instead of maintaining its own table. Additional event-owner packages are dev dependencies and project references of `dsh-invariants`, not peer dependencies, so the compile-time aggregation does not expand the plugin's runtime closure.
### Semantic gaps fail explicitly
The generators reject missing declarations, config diagnostics, widened or generic event names, inconsistent routing-key types, ambiguous payload matches, unnecessary unsupported annotations, and stale generated output. Recovery through local helper call sites is deliberately narrow: exported or unresolved dataflow requires a new semantic rule rather than a package-specific override.
## Verification
`verify-doc-graphs` freshness-checks semantic producer/listener discovery, and `verify-scoped-events` freshness-checks the generated resolver map. The root TypeScript build compiles the resolver against merged `Events`; workspace constraints and runtime-closure checks ensure its type-only aggregation does not become a deployment dependency.
## Alternatives considered
- **Keep syntax-only scans with receiver allowlists and manual overrides.** This is simple per exception but makes renames and new helper shapes update a second representation. Completeness can detect a missing producer, but it cannot prove that the override still describes the source.
## Consequences
- Event relation generation follows semantic receiver identity and closed event values instead of local naming conventions.
- Scoped-event membership, subject extraction, and runtime invariant coverage come from event declarations and real dispatch contracts rather than handwritten tables.
- Refactors that change event names, parameter positions, subject properties, or routing-key types fail generation or compilation at the owning contract.
- Building a flattened Program costs more startup time and memory than parsing isolated files, and semantic gates depend on a valid root project graph.
- Generated TypeScript remains committed source: changes to event owners or dispatch shapes must regenerate it and the affected documentation.

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# RFC: 基于 TypeScript Program 的语义门禁
Status: implemented
[English](2026-07-14-typescript-program-backed-semantic-gates.md) | 中文
## 问题
仓库门禁有时需要判断 TypeScript 语法本身不携带的事实:接收者是否为 Cordis `Context`、哪些具体事件名会进入转发辅助函数、声明合并是否改变了事件签名。
当前的门禁基于 TypeScript 单文件语法解析能力使用命名约定、手写的表格、JSDoc 等方式来维护这类信息。
仓库需要一个语义真源同时不能引入运行时包package之间的循环依赖、宽泛的兜底启发式逻辑或重复描述 TypeScript 已有信息的机器可读标注。
## 决策
仓库可以通过项目级类型信息 `ts.Program` 进行跨文件项目类型联合计算,并通过 `TypeChecker` 来提取 **强类型** 信息用以缓解原有命名约定、手写表格、JSDoc 标注等形式。
当前已完成 A / B 两个门禁的语义化改造。
### 一个项目模型展开根项目配置
[`TypeScriptProject`](../../../../scripts/ts-project.ts) 解析根 `tsconfig.json`,递归展开每个项目引用,并将各引用项目的源码根合并为一个不输出文件的语义 Program。直接从根项目配置创建普通 Program 时TypeScript 可能将引用项目重定向到构建后的声明文件;显式展开可以让门禁继续遍历各包的 `src` 文件,并使用真实符号标识。
该封装统一负责配置诊断、语义编译选项、仓库相对路径、源码查找和共享 TypeChecker。各门禁不再自行按文件通配模式扫描包源码也不再分别构建不完整的 Program。
### A. 事件关系由接收者类型和值类型决定
[`gen-doc-graphs`](../../../../scripts/gen-doc-graphs.ts) 根据调用接收者与仓库中真实 `Context``AgentEventDispatch` 和 Cordis `EventsService` 类型之间的可赋值关系进行分类。变量名和属性拼写不再决定某次调用是否属于事件操作。
Context 与 AgentEventDispatch 调用只贡献有限的字符串字面量事件集合。对于直接调用 `EventsService.dispatch()` 的路径,生成器会沿数组字面量、常量别名、条件分支和未导出本地辅助函数的已解析调用点恢复事件槽位。泛型转发参数不算作具体生产方:事件仍归属于传入封闭事件值的调用点。
每个已声明的 harness 事件都必须存在扫描得到的生产方。找不到生产方时,生成过程会将其视为无调用方的事件词汇或尚不支持的语义 dispatch 形态并明确失败;没有监听方的扩展点仍然合法。`internal/dispatch` 插桩不会被当作它所观察的每个事件的订阅,因此关系矩阵只记录直接的产品监听方,不再手工补充间接关系。
### B. 带作用域的事件路由生成一份强类型解析函数表
[`gen-scoped-events`](../../../../scripts/gen-scoped-events.ts) 扫描真实的 `scopeTarget(base, key)` 调用,为每种 scoped 基础对象确定路由键类型。随后,它查找带有 `this: Scoped<Base>` 的 Cordis `Events` 成员,并在每个事件参数及其一层公开属性中搜索类型;移除 `null``undefined` 后,候选类型必须与路由键类型完全相同。
恰好一个匹配项会生成解析函数。存在多个匹配项时,含义不明确,生成器会失败。没有匹配项时,事件必须标记 `@dshScopeScan unsupported`;该标记只用于路由键有意留在事件参数之外的情况,例如按所属 agent智能体路由的会话事件和按父 agent 路由的 subagent 生命周期事件。此标记只表示扫描不受支持,不编码事件名、参数下标、属性路径或替代类型。
仓库提交的 [`scoped-events.generated.ts`](../../../../packages/support/invariants/src/scoped-events.generated.ts) 会导入每个带作用域的事件声明方,使它们从类型侧合并进 `Events`。每个生成函数都接收 `Parameters<Events[K]>`,完整对象则满足基于 `ScopedEventName` 联合类型派生出的 `Record`。因此,常规 TypeScript 编译会检查事件是否存在、参数位置、属性访问和带作用域的事件集合完整性。唯一的类型断言只负责将 Cordis 运行时的 `unknown[]` dispatch 边界适配到已经通过类型检查的解析函数。
不变式插件消费这份生成的运行时表,不再维护自己的事件表。新增的事件声明方包只作为 `dsh-invariants` 的开发依赖和项目引用存在,不进入对等依赖,因此编译期聚合不会扩大插件的运行时依赖闭包。
### 语义缺口必须显式失败
遇到声明缺失、配置诊断、事件名被拓宽或保持泛型、路由键类型不一致、事件参数匹配不唯一、不必要的 unsupported 标记,或生成产物陈旧时,生成器都会拒绝继续。通过本地辅助函数调用点恢复信息的能力被刻意限制在窄范围内:如果数据流经过导出或无法解析的边界,应新增通用语义规则,而不是添加特定包的覆盖项。
## 验证
`verify-doc-graphs` 对语义生产方/监听方扫描执行新鲜度检查,`verify-scoped-events` 对生成的解析函数表执行新鲜度检查。根 TypeScript 构建会将解析函数与合并后的 `Events` 一起编译workspace 约束和运行时依赖闭包检查则确保仅参与类型聚合的依赖不会变成部署依赖。
## 考虑过的替代方案
- **保留语法扫描、接收者白名单和手写覆盖项。** 每个例外都容易单独处理,但重命名和新增辅助函数形态时还必须更新第二份表示。完整性检查能够发现生产方缺失,却无法证明覆盖项仍与源码一致。
## 后果
- 事件关系生成依据语义接收者身份和封闭事件值,不再依赖局部命名约定;
- 带作用域的事件成员关系、主体提取和运行时不变式覆盖来自事件声明与真实 dispatch 契约,不再来自手写表;
- 修改事件名、参数位置、主体属性或路由键类型时,会在其所属契约处触发生成或编译失败;
- 构建扁平化 Program 比解析孤立文件消耗更多启动时间和内存,语义门禁也依赖有效的根项目图;
- 生成的 TypeScript 仍属于提交到仓库的源码:事件声明方或 dispatch 形态发生变化后,必须重新生成该文件和受影响的文档。

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