fix(scope): close final ownership races

Drain idle injection flushes before agent teardown, snapshot approval and subagent provider inputs, and gate subagent lifecycle events on real child readiness. Align the RFCs and generated contracts with the hardened behavior.
This commit is contained in:
Tianyi Cui
2026-07-12 00:31:46 +08:00
parent e6c7522a75
commit 3529b3c166
43 changed files with 825 additions and 261 deletions

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@@ -745,7 +745,7 @@ export interface Config {
Depends on: [`SubagentCapabilities`](../packages/subagent/subagent/src/index.ts) · [`SubagentStopReason`](../packages/subagent/subagent/src/index.ts)
Source: [`packages/support/subagent-mock/src/index.ts:84`](../packages/support/subagent-mock/src/index.ts)
Source: [`packages/support/subagent-mock/src/index.ts:87`](../packages/support/subagent-mock/src/index.ts)
## `@deepseek-ai/dsh-subagent-spawn`
@@ -1019,7 +1019,7 @@ export interface Config {
export type ApprovalPolicy = 'ask' | 'never'
```
Source: [`packages/ui/user-approval/src/index.ts:263`](../packages/ui/user-approval/src/index.ts)
Source: [`packages/ui/user-approval/src/index.ts:268`](../packages/ui/user-approval/src/index.ts)
## `@deepseek-ai/dsh-web`

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@@ -23,7 +23,7 @@ An agent's fully composed scoped world was published in the AgentRegistry. Its s
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:298`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:300`](../../packages/core/agent/src/types.ts)
### `agent/disposed` — emit
@@ -35,7 +35,7 @@ An agent was removed from the registry after its driver and any in-flight turn r
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:312`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:314`](../../packages/core/agent/src/types.ts)
### `agent/error` — emit
@@ -47,7 +47,7 @@ A step or turn errored. The loop reports a failure here (plus the logger) even w
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:585`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:587`](../../packages/core/agent/src/types.ts)
### `agent/pre-step` — serial
@@ -61,7 +61,7 @@ Serial (awaited in registration order), not a waterfall: a listener mutates the
Types: [Agent](../core-data-structures/core.md) · [Message](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:417`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:419`](../../packages/core/agent/src/types.ts)
### `agent/prompt-submit` — waterfall
@@ -73,7 +73,7 @@ Waterfall: decide what happens to ONE drained queued message before it becomes a
Types: [Agent](../core-data-structures/core.md) · [ContentBlock](../core-data-structures/core.md) · [MessageSource](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:435`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:437`](../../packages/core/agent/src/types.ts)
### `agent/queued` — emit
@@ -85,7 +85,7 @@ A message entered the agent's inbox (queued or steering). `source` is the resolv
Types: [Agent](../core-data-structures/core.md) · [ContentBlock](../core-data-structures/core.md) · [MessageSource](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:340`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:342`](../../packages/core/agent/src/types.ts)
### `agent/request` — waterfall
@@ -97,7 +97,7 @@ Waterfall: shape the step's call configuration — model switching, sampling ove
Types: [Agent](../core-data-structures/core.md) · [LlmCallConfig](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:464`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:466`](../../packages/core/agent/src/types.ts)
### `agent/session-prefix` — waterfall
@@ -113,7 +113,7 @@ The seed is a frozen empty list; a contributing listener returns a NEW array —
Types: [Agent](../core-data-structures/core.md) · [Message](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:516`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:518`](../../packages/core/agent/src/types.ts)
### `agent/session-start` — emit
@@ -125,7 +125,7 @@ The agent's session lifecycle began, fired once before its first turn. `source`
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:360`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:362`](../../packages/core/agent/src/types.ts)
### `agent/status` — emit
@@ -137,7 +137,7 @@ Agent status changed (`idle` ⇄ `running`, or → `disposed`). Drive lifecycle
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:326`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:328`](../../packages/core/agent/src/types.ts)
### `agent/step-result` — waterfall
@@ -149,7 +149,7 @@ Waterfall: post-process the assembled assistant Message before tool dispatch (va
Types: [Agent](../core-data-structures/core.md) · [Message](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:531`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:533`](../../packages/core/agent/src/types.ts)
### `agent/turn-continuation` — waterfall
@@ -161,7 +161,7 @@ Waterfall: override the turn-continuation decision via a typed ContinuationDecis
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:549`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:551`](../../packages/core/agent/src/types.ts)
### `agent/turn-stop` — serial
@@ -173,13 +173,13 @@ Serial terminal-stop checkpoint after the ordinary `agent/turn-continuation` wat
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:568`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:570`](../../packages/core/agent/src/types.ts)
## `approval/*`
### `approval/request` — waterfall
Waterfall asking the composed answerers to decide one approval request. Dispatched only from ApprovalService.request — callers go through the service (which owns cancellation and the audit events), never through `ctx.waterfall` directly. A listener that can answer for this request's agent returns an outcome WITHOUT calling `next()` (the decision slot is single-occupancy, first listener to answer wins); a listener that does not recognize the agent MUST call `next()` so another answerer — or the fail-closed default `'unavailable'` — gets the question. Throwing is contained by the service and yields `'unavailable'`. Scope-filtered dispatch (`@deepseek-ai/dsh-scope`) keys the carrier by `req.agent`: a listener registered through `agent.ctx` receives only that agent's questions, while a plain-context listener receives every agent's.
Waterfall asking the composed answerers to decide one approval request. Dispatched only from ApprovalService.request — callers go through the service (which owns cancellation and the audit events), never through `ctx.waterfall` directly. A listener that can answer for this request's agent returns an outcome WITHOUT calling `next()` (the decision slot is single-occupancy, first listener to answer wins); a listener that does not recognize the agent MUST call `next()` so another answerer — or the fail-closed default `'unavailable'` — gets the question. Throwing is contained by the service and yields `'unavailable'`. Scope-filtered dispatch (`@deepseek-ai/dsh-scope`) keys the carrier by `req.agent`: a listener registered through `agent.ctx` receives only that agent's questions, while a plain-context listener receives every agent's. `req` is the service's shallow-frozen acceptance snapshot: later caller mutation cannot redirect the question, while the `agent` and `signal` identity capabilities remain exact.
```ts cordis-catalog
'approval/request'(this: Scoped<ApprovalService>, req: ApprovalRequest, next: () => Promise<ApprovalOutcome>): Promise<ApprovalOutcome>
@@ -187,7 +187,7 @@ Waterfall asking the composed answerers to decide one approval request. Dispatch
Types: [ApprovalOutcome](../core-data-structures/approval.md) · [ApprovalRequest](../core-data-structures/approval.md)
Source: [`packages/ui/user-approval/src/index.ts:69`](../../packages/ui/user-approval/src/index.ts)
Source: [`packages/ui/user-approval/src/index.ts:72`](../../packages/ui/user-approval/src/index.ts)
## `fs/*`
@@ -301,13 +301,13 @@ Source: [`packages/skill/skill/src/index.ts:136`](../../packages/skill/skill/src
### `subagent/end` — emit
A subagent run settled — emitted when SubagentRun.result resolves (any stop reason). Paired with Events['subagent/start']. Scope-filtered dispatch (`@deepseek-ai/dsh-scope`): the carrier is keyed by the DELEGATING PARENT — a listener registered through the parent's `agent.ctx` observes only its own delegations; a plain plugin listener observes every run.
A started subagent run settled — emitted when SubagentRun.result resolves (any stop reason) or rejects (reported as `error`). Paired with Events['subagent/start']; a run whose readiness rejected emits neither event. Scope-filtered dispatch (`@deepseek-ai/dsh-scope`): the carrier is keyed by the DELEGATING PARENT — a listener registered through the parent's `agent.ctx` observes only its own delegations; a plain plugin listener observes every run.
```ts cordis-catalog
'subagent/end'(this: Scoped<SubagentService>, info: SubagentRunEndInfo): void
```
Source: [`packages/subagent/subagent/src/index.ts:109`](../../packages/subagent/subagent/src/index.ts)
Source: [`packages/subagent/subagent/src/index.ts:114`](../../packages/subagent/subagent/src/index.ts)
### `subagent/provider-added` — emit
@@ -331,13 +331,13 @@ Source: [`packages/subagent/subagent/src/index.ts:86`](../../packages/subagent/s
### `subagent/start` — emit
A subagent run started — emitted after the provider is resolved and its capabilities validated, as the child run begins. Paired with Events['subagent/end']. Scope-filtered dispatch (`@deepseek-ai/dsh-scope`): the carrier is keyed by the DELEGATING PARENT — a listener registered through the parent's `agent.ctx` observes only its own delegations; a plain plugin listener observes every run.
A subagent run started — emitted only after SubagentRun.started fulfills, when the provider has established a live child. For an in-process provider, `ctx.agents.get(info.id)` is therefore guaranteed to resolve during this notification. A readiness rejection emits neither lifecycle event; every emitted start is paired with Events['subagent/end']. Scope-filtered dispatch (`@deepseek-ai/dsh-scope`): the carrier is keyed by the DELEGATING PARENT — a listener registered through the parent's `agent.ctx` observes only its own delegations; a plain plugin listener observes every run.
```ts cordis-catalog
'subagent/start'(this: Scoped<SubagentService>, info: SubagentRunInfo): void
```
Source: [`packages/subagent/subagent/src/index.ts:98`](../../packages/subagent/subagent/src/index.ts)
Source: [`packages/subagent/subagent/src/index.ts:101`](../../packages/subagent/subagent/src/index.ts)
## `system-prompt/*`

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@@ -40,7 +40,7 @@ list(): Agent[]
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/index.ts:168`](../../packages/core/agent/src/index.ts)
Source: [`packages/core/agent/src/index.ts:169`](../../packages/core/agent/src/index.ts)
## `ctx.approval` — `ApprovalService`
@@ -54,7 +54,7 @@ async request(req: ApprovalRequest): Promise<ApprovalOutcome>
Types: [ApprovalOutcome](../core-data-structures/approval.md) · [ApprovalRequest](../core-data-structures/approval.md)
Source: [`packages/ui/user-approval/src/index.ts:287`](../../packages/ui/user-approval/src/index.ts)
Source: [`packages/ui/user-approval/src/index.ts:292`](../../packages/ui/user-approval/src/index.ts)
## `ctx.bash` — `BashExecutor` (abstract seam)
@@ -246,7 +246,7 @@ list(): string[]
start(name: string, request: SubagentStartRequest): SubagentRun
```
Source: [`packages/subagent/subagent/src/index.ts:155`](../../packages/subagent/subagent/src/index.ts)
Source: [`packages/subagent/subagent/src/index.ts:160`](../../packages/subagent/subagent/src/index.ts)
## `ctx.systemPrompt` — `SystemPrompt`

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@@ -62,11 +62,12 @@ interface SubagentStopReasonMap {
## A live run: `SubagentRun`
The handle the consumer holds while a child executes. The consumer awaits `result`, may `cancel` mid-flight, and MUST `dispose` on every path to reach child quiescence (no leaked idle child / session). `result` does NOT reject on a child-level failure — a model/transport failure resolves with `stopReason: 'error'` — so the consumer maps a non-`completed` reason to an `isError` result; it rejects only on an infrastructure fault the seam cannot represent. `sendMessage` and `resume` are OPTIONAL: a provider that supports the runtime capability defines the method; one that doesn't omits it.
The handle the consumer holds while a child executes. `started` is the provider's publication boundary: it resolves only after an in-process agent is live in `ctx.agents` or a remote transport has created its child session, and rejects when the attempt fails or is cancelled before that point. The consumer normally awaits `result`, may `cancel` mid-flight, and MUST `dispose` on every path to reach child quiescence (no leaked idle child / session). `result` does NOT reject on a child-level failure — a model/transport failure resolves with `stopReason: 'error'` — so the consumer maps a non-`completed` reason to an `isError` result; it rejects only on an infrastructure fault the seam cannot represent. `sendMessage` and `resume` are OPTIONAL: a provider that supports the runtime capability defines the method; one that doesn't omits it.
```ts type-equiv
interface SubagentRun {
readonly id: AgentId
readonly started: Promise<void>
readonly result: Promise<SubagentResult>
cancel(reason?: string): void
dispose(): Promise<void>
@@ -88,11 +89,11 @@ interface SubagentProvider {
}
```
The service (`ctx.subagents`) emits `subagent/start` when a run begins and `subagent/end` when it settles (see the [events catalog](../cordis-catalog/events.md)). `subagent/end` carries `lastAssistantMessage` (the child's final `output`) on the settle path, so an observer sees WHAT the subagent produced without holding the run (absent when the run rejected at the infrastructure level — no result was produced). These are **observe-only** events: both are plain `emit`s (the `subagent/end` fires from a detached `.then` after the result settles and awaits no listener), so a subscriber observes but cannot change the run. Both emits contain a thrown listener **per listener** (logged, never propagated): one bad subscriber can neither strand a live run, surface as an unhandled rejection on the detached settle hook, nor starve the listeners registered after it.
The service (`ctx.subagents`) emits `subagent/start` only after `run.started` fulfills and emits the paired `subagent/end` when that started run settles (see the [events catalog](../cordis-catalog/events.md)); a pre-publication readiness rejection emits neither event. For an in-process provider, a start listener can therefore resolve the live child with `ctx.agents.get(info.id)`; a remote provider need not publish into the local registry. `subagent/end` carries `lastAssistantMessage` (the child's final `output`) on the settle path, so an observer sees WHAT the subagent produced without holding the run (absent when the run rejected at the infrastructure level — no result was produced). These are **observe-only** events: both are plain `emit`s, so a subscriber observes but cannot change the run. Result settlement is observed immediately even while readiness is pending, then its cloned end payload is buffered until start has been announced; this prevents an early rejection from becoming unhandled while preserving start-before-end order and protecting the caller's result from listener mutation. Both emits contain a thrown listener **per listener** (logged, never propagated): one bad subscriber can neither strand a live run, surface as an unhandled rejection on the detached settle hook, nor starve the listeners registered after it.
## In-process backends: depth and seed
The two in-process backends ([dsh-subagent-spawn](../../packages/subagent/subagent-spawn) fresh, [dsh-subagent-fork](../../packages/subagent/subagent-fork) seeded) run the child as a child `Agent` on the same application. They synchronously snapshot caller-owned data, install provider ownership before attaching the abort listener, create one run-owner fiber under `parent.ctx`, and invoke the factory through that fiber: parent teardown, provider teardown, and manual run disposal share the same pre-publication ownership and quiescence boundary, while the child still receives a flat new scope rather than inheriting the parent's capabilities. Two pieces of vocabulary ride on the existing agent/session types rather than new core types:
The two in-process backends ([dsh-subagent-spawn](../../packages/subagent/subagent-spawn) fresh, [dsh-subagent-fork](../../packages/subagent/subagent-fork) seeded) run the child as a child `Agent` on the same application. They synchronously snapshot caller-owned data, install provider ownership before attaching the abort listener, create one run-owner fiber under `parent.ctx`, and invoke the factory through that fiber: parent teardown, provider teardown, and manual run disposal share the same pre-publication ownership and quiescence boundary, while the child still receives a flat new scope rather than inheriting the parent's capabilities. Their `started` promise projects the factory's successful publication and the result driver awaits that same promise before sending the prompt. Two pieces of vocabulary ride on the existing agent/session types rather than new core types:
- **Delegation depth** is a merge-extensible `AgentOptions.subagentDepth` field (`0` for a top-level agent, parent + 1 for a child). The seam owns it — the loop neither sets nor reads it — so a nested spawn reads its parent's depth from `parent.options.subagentDepth` and the `depthLimit` capability caps the tree by refusing a child whose depth would exceed `request.maxDepth`.
- **Fork seeding** uses `CreateAgentOptions.seed` (a `SessionEvent[]` prefix threaded through `AgentLoop.createAgent` → `ctx.sessions.prepare({ seed })`, the same primitive `resume` uses). The fork backend passes a *balanced completed-turn prefix* of the parent's log — the parent's events up to and including its last `turn/end` — so the seed is contiguous-from-0 and the [invariants](../../packages/support/invariants) replay accepts it (the in-flight, unbalanced turn is excluded).

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@@ -175,7 +175,7 @@ type PostToolDecision =
| { kind: 'block'; feedback: ContentBlock[]; additionalContext?: HookContext }
```
Call `next()` to delegate to the default (allow / dispatch / accept-unchanged), or return a decision/result to short-circuit. A `pre-execute` `deny` (or `ask`, which degrades to deny until the permission system lands) skips dispatch and yields an `isError` result; a registered `ToolGuard` runs after that waterfall and can impose a final denial. Input rewrite is deliberately NOT offered on `PreToolDecision` because it would desync the pre-execution audit/history/UI from what ran. A `post-execute` `accept` may replace the model-facing `content`; a `block` turns the call into an `isError` whose content is the corrective `feedback`. The awaited `tools/result` notification then receives the frozen execution identity and a deep-frozen result snapshot after every wrapper, post decision, and outer error catch; observers cannot transform the outcome or race each other through payload mutation, and one observer failure neither changes the result nor starves peers. An unregistered tool routes through the same catch as a tool-thrown error, so both failure classes get a structured `{ name, code }` (`ToolNotFoundError` → `UNKNOWN_TOOL`) — the loop records a failed tool call instead of failing the whole turn.
Call `next()` to delegate to the default (allow / dispatch / accept-unchanged), or return a decision/result to short-circuit. A `pre-execute` `deny` skips dispatch and yields an `isError` result. An `ask` resolves through the optional approval seam: only `allowed-once` proceeds, while every non-grant, missing channel/service, or agent-less request becomes a normalized denial. A registered `ToolGuard` then runs and can still impose a final denial. Input rewrite is deliberately NOT offered on `PreToolDecision` because it would desync the pre-execution audit/history/UI from what ran. A `post-execute` `accept` may replace the model-facing `content`; a `block` turns the call into an `isError` whose content is the corrective `feedback`. The awaited `tools/result` notification then receives the frozen execution identity and a deep-frozen result snapshot after every wrapper, post decision, and outer error catch; observers cannot transform the outcome or race each other through payload mutation, and one observer failure neither changes the result nor starves peers. An unregistered tool routes through the same catch as a tool-thrown error, so both failure classes get a structured `{ name, code }` (`ToolNotFoundError` → `UNKNOWN_TOOL`) — the loop records a failed tool call instead of failing the whole turn.
## The structured-output schema subset

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@@ -7,20 +7,20 @@ This matrix shows which packages dispatch each harness-owned event and which pac
| Event | Mode | Declared in | Dispatchers | Listeners |
| --- | --- | --- | --- | --- |
| `agent/created` | `emit` | [`packages/core/agent/src/types.ts:298`](../packages/core/agent/src/types.ts) | [`agent`](../packages/core/agent) (`emit`) | [`stdio-agent`](../packages/ui/stdio-agent) |
| `agent/disposed` | `emit` | [`packages/core/agent/src/types.ts:312`](../packages/core/agent/src/types.ts) | [`agent`](../packages/core/agent) (`emit`) | [`stdio-agent`](../packages/ui/stdio-agent) |
| `agent/error` | `emit` | [`packages/core/agent/src/types.ts:585`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | - |
| `agent/pre-step` | `serial` | [`packages/core/agent/src/types.ts:417`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`serial`) | [`compact-basic`](../packages/compact/compact-basic), [`user-approval`](../packages/ui/user-approval) |
| `agent/prompt-submit` | `waterfall` | [`packages/core/agent/src/types.ts:435`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | [`acp`](../packages/ui/acp), [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex), [`repeat-tool-guard`](../packages/guard/repeat-tool-guard) |
| `agent/queued` | `emit` | [`packages/core/agent/src/types.ts:340`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | - |
| `agent/request` | `waterfall` | [`packages/core/agent/src/types.ts:464`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | - |
| `agent/session-prefix` | `waterfall` | [`packages/core/agent/src/types.ts:516`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | [`tool-skill`](../packages/skill/tool-skill) |
| `agent/session-start` | `emit` | [`packages/core/agent/src/types.ts:360`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex), [`invariants`](../packages/support/invariants) |
| `agent/status` | `emit` | [`packages/core/agent/src/types.ts:326`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | [`acp`](../packages/ui/acp), [`invariants`](../packages/support/invariants), [`repeat-tool-guard`](../packages/guard/repeat-tool-guard), [`stdio-agent`](../packages/ui/stdio-agent) |
| `agent/step-result` | `waterfall` | [`packages/core/agent/src/types.ts:531`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | - |
| `agent/turn-continuation` | `waterfall` | [`packages/core/agent/src/types.ts:549`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex) |
| `agent/turn-stop` | `serial` | [`packages/core/agent/src/types.ts:568`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`strictSerial (serial)`) | [`subagent-inprocess`](../packages/subagent/subagent-inprocess) |
| `approval/request` | `waterfall` | [`packages/ui/user-approval/src/index.ts:69`](../packages/ui/user-approval/src/index.ts) | [`user-approval`](../packages/ui/user-approval) (`waterfall`) | [`acp`](../packages/ui/acp) |
| `agent/created` | `emit` | [`packages/core/agent/src/types.ts:300`](../packages/core/agent/src/types.ts) | [`agent`](../packages/core/agent) (`emit`) | [`stdio-agent`](../packages/ui/stdio-agent) |
| `agent/disposed` | `emit` | [`packages/core/agent/src/types.ts:314`](../packages/core/agent/src/types.ts) | [`agent`](../packages/core/agent) (`emit`) | [`stdio-agent`](../packages/ui/stdio-agent) |
| `agent/error` | `emit` | [`packages/core/agent/src/types.ts:587`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | - |
| `agent/pre-step` | `serial` | [`packages/core/agent/src/types.ts:419`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`serial`) | [`compact-basic`](../packages/compact/compact-basic), [`user-approval`](../packages/ui/user-approval) |
| `agent/prompt-submit` | `waterfall` | [`packages/core/agent/src/types.ts:437`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | [`acp`](../packages/ui/acp), [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex), [`repeat-tool-guard`](../packages/guard/repeat-tool-guard) |
| `agent/queued` | `emit` | [`packages/core/agent/src/types.ts:342`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | - |
| `agent/request` | `waterfall` | [`packages/core/agent/src/types.ts:466`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | - |
| `agent/session-prefix` | `waterfall` | [`packages/core/agent/src/types.ts:518`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | [`tool-skill`](../packages/skill/tool-skill) |
| `agent/session-start` | `emit` | [`packages/core/agent/src/types.ts:362`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex), [`invariants`](../packages/support/invariants) |
| `agent/status` | `emit` | [`packages/core/agent/src/types.ts:328`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | [`acp`](../packages/ui/acp), [`invariants`](../packages/support/invariants), [`repeat-tool-guard`](../packages/guard/repeat-tool-guard), [`stdio-agent`](../packages/ui/stdio-agent) |
| `agent/step-result` | `waterfall` | [`packages/core/agent/src/types.ts:533`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | - |
| `agent/turn-continuation` | `waterfall` | [`packages/core/agent/src/types.ts:551`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex) |
| `agent/turn-stop` | `serial` | [`packages/core/agent/src/types.ts:570`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`strictSerial (serial)`) | [`subagent-inprocess`](../packages/subagent/subagent-inprocess) |
| `approval/request` | `waterfall` | [`packages/ui/user-approval/src/index.ts:72`](../packages/ui/user-approval/src/index.ts) | [`user-approval`](../packages/ui/user-approval) (`waterfall`) | [`acp`](../packages/ui/acp) |
| `fs/edit-intent` | `waterfall` | [`packages/fs/fs/src/index.ts:123`](../packages/fs/fs/src/index.ts) | [`tool-fs`](../packages/fs/tool-fs) (`waterfall`) | [`fs-policy`](../packages/fs/fs-policy) |
| `fs/observed` | `emit` | [`packages/fs/fs/src/index.ts:138`](../packages/fs/fs/src/index.ts) | [`tool-fs`](../packages/fs/tool-fs) (`emit`) | [`fs-policy`](../packages/fs/fs-policy) |
| `fs/write-intent` | `waterfall` | [`packages/fs/fs/src/index.ts:109`](../packages/fs/fs/src/index.ts) | [`tool-fs`](../packages/fs/tool-fs) (`waterfall`) | [`fs-policy`](../packages/fs/fs-policy) |
@@ -30,10 +30,10 @@ This matrix shows which packages dispatch each harness-owned event and which pac
| `session/flush` | `parallel` | [`packages/core/session/src/index.ts:79`](../packages/core/session/src/index.ts) | [`session`](../packages/core/session) (`parallel`) | [`session-persistence`](../packages/session-persistence/session-persistence) |
| `skill/provider-added` | `emit` | [`packages/skill/skill/src/index.ts:130`](../packages/skill/skill/src/index.ts) | [`skill`](../packages/skill/skill) (`emit`) | - |
| `skill/provider-removed` | `emit` | [`packages/skill/skill/src/index.ts:136`](../packages/skill/skill/src/index.ts) | [`skill`](../packages/skill/skill) (`emit`) | - |
| `subagent/end` | `emit` | [`packages/subagent/subagent/src/index.ts:109`](../packages/subagent/subagent/src/index.ts) | [`subagent`](../packages/subagent/subagent) (`events.dispatch`) | [`hooks-claude`](../packages/hooks/hooks-claude) |
| `subagent/end` | `emit` | [`packages/subagent/subagent/src/index.ts:114`](../packages/subagent/subagent/src/index.ts) | [`subagent`](../packages/subagent/subagent) (`events.dispatch`) | [`hooks-claude`](../packages/hooks/hooks-claude) |
| `subagent/provider-added` | `emit` | [`packages/subagent/subagent/src/index.ts:75`](../packages/subagent/subagent/src/index.ts) | [`subagent`](../packages/subagent/subagent) (`emit`) | [`tool-subagent`](../packages/subagent/tool-subagent) |
| `subagent/provider-removed` | `emit` | [`packages/subagent/subagent/src/index.ts:86`](../packages/subagent/subagent/src/index.ts) | [`subagent`](../packages/subagent/subagent) (`events.dispatch`) | [`tool-subagent`](../packages/subagent/tool-subagent) |
| `subagent/start` | `emit` | [`packages/subagent/subagent/src/index.ts:98`](../packages/subagent/subagent/src/index.ts) | [`subagent`](../packages/subagent/subagent) (`events.dispatch`) | [`hooks-claude`](../packages/hooks/hooks-claude) |
| `subagent/start` | `emit` | [`packages/subagent/subagent/src/index.ts:101`](../packages/subagent/subagent/src/index.ts) | [`subagent`](../packages/subagent/subagent) (`events.dispatch`) | [`hooks-claude`](../packages/hooks/hooks-claude) |
| `system-prompt/assemble` | `waterfall` | [`packages/core/system-prompt/src/index.ts:45`](../packages/core/system-prompt/src/index.ts) | [`system-prompt`](../packages/core/system-prompt) (`waterfall`) | - |
| `system-prompt/change` | `emit` | [`packages/core/system-prompt/src/index.ts:55`](../packages/core/system-prompt/src/index.ts) | [`system-prompt`](../packages/core/system-prompt) (`emit`) | - |
| `tools/change` | `emit` | [`packages/core/tools/src/index.ts:176`](../packages/core/tools/src/index.ts) | [`tools`](../packages/core/tools) (`emit`) | - |

View File

@@ -23,7 +23,7 @@ An approval question was put to the answerer chain — log-only audit (like `hoo
Types: [CallId](core-data-structures/core.md)
Source: [`packages/ui/user-approval/src/index.ts:83`](../packages/ui/user-approval/src/index.ts)
Source: [`packages/ui/user-approval/src/index.ts:86`](../packages/ui/user-approval/src/index.ts)
#### `approval/decided` — log-only
@@ -33,7 +33,7 @@ The outcome of a prior `approval/asked` (same `id`) — log-only audit. Exactly
'approval/decided': { id: ApprovalRequestId; outcome: ApprovalOutcome }
```
Source: [`packages/ui/user-approval/src/index.ts:94`](../packages/ui/user-approval/src/index.ts)
Source: [`packages/ui/user-approval/src/index.ts:97`](../packages/ui/user-approval/src/index.ts)
#### `approval/policy` — log-only
@@ -43,7 +43,7 @@ The session's approval policy was switched — log-only, durable, replayable, ne
'approval/policy': { policy: ApprovalPolicy }
```
Source: [`packages/ui/user-approval/src/index.ts:106`](../packages/ui/user-approval/src/index.ts)
Source: [`packages/ui/user-approval/src/index.ts:109`](../packages/ui/user-approval/src/index.ts)
### `assistant/*`

View File

@@ -206,6 +206,8 @@ The operation being described determines the key; callers cannot attach an unrel
| `session/created`, `session/event`, `session/flush` | The owner scope captured when the session enters the store |
| `subagent/start`, `subagent/end` | The delegating parent agent |
Approval requests cross an asynchronous answer boundary, so the service snapshots the accepted record synchronously. It preserves the exact agent and abort-signal identities but copies the scalar fields, captures the agent's session once, and uses that one snapshot for `approval/asked`, scoped dispatch, cancellation, policy, and `approval/decided`. Mutating the caller-owned record after `request()` returns therefore cannot split the audit pair or redirect the question to another agent's listeners.
The dispatch rule can be read independently of Cordis internals:
```text
@@ -334,12 +336,11 @@ The sequence is not described as atomic because observers run between its steps.
### Teardown stops work before revoking its world
Every owner path uses the same reverse order: stop the loop and await its actual exit, remove the agent from the registry, detach the session, then unwind the scope. The final session events and durability flush therefore happen while the session and scoped listeners are still live.
Every owner path uses the same reverse order: stop the loop and await its actual exit plus every agent-started durability checkpoint, remove the agent from the registry, detach the session, then unwind the scope. Final turn events, the turn-ending flush, and any outstanding idle-injection flush therefore settle while the session and scoped listeners are still live.
```text
disposeOwnedAgent(world):
world.stopDriver()
await world.agent.done # waits for any in-flight turn close and flush
await world.stopDriver() # waits for loop exit and all agent-started flushes
world.detachAgent() # emits agent/disposed when announced
world.detachSession()
await world.scope.dispose()
@@ -519,10 +520,14 @@ In-process subagents demonstrate how the scope, lifecycle, and final-policy piec
### Inputs and ownership are fixed before asynchronous creation
Provider registration first freezes an acceptance snapshot of the provider name, capability flags, parent-context descriptor, and `start` callback; the callback is bound to the original provider receiver so its intentional internal state stays live. Lookup, validation, model-facing wording, dispatch, lifecycle notifications, and HMR cleanup all use that snapshot. Mutating or reusing the caller's provider object later therefore cannot rename a live entry, change its advertised powers, replace its callback, or make its disposer delete the wrong key.
Starting a run snapshots every accepted field before asynchronous owner setup. The parent and abort signal are retained as identity capabilities but never reread from the mutable request record; tool filters, seed events, agent options, output schema, and prompt are detached. The schema is validated before cloning, while the prompt must pass the same lossless-JSON check before and after cloning that the session log requires. Later caller mutation therefore cannot change lifecycle scope, configuration, the schema enforced by the capture tool, or the prompt eventually logged and sent.
The driver first installs provider ownership. Only after that succeeds does it attach the request's abort listener and create one run-owner Cordis fiber under `parent.ctx`; an already-unloading provider therefore leaves neither a child nor an orphaned listener. The child factory runs through the owner fiber. Parent teardown, provider teardown, and manual run disposal all dispose this same node; moving it out of the active state synchronously prevents an unpublished setup from publishing afterward, while all three paths follow one quiescence promise. This structured ownership does not change the child's flat capability view.
The returned run separates acceptance from publication with `started: Promise<void>`. For spawn and fork, it fulfills only after the child factory returns a published handle, so the service can emit `subagent/start` with `ctx.agents.get(run.id)` already live; it rejects when rollback prevents publication. The service observes `result` immediately but buffers its cloned end payload until readiness, preserving start-before-end order without leaving an early rejection unhandled. A readiness rejection emits neither lifecycle event. The result driver awaits the same boundary before sending the child prompt.
```text
startInProcessRun(providerContext, acceptedRequest):
snapshot all request data, including parent identity
@@ -535,11 +540,21 @@ startInProcessRun(providerContext, acceptedRequest):
dispose providerLink
await disposeRunOwner()
childHandle = await runOwner.ctx.agents.create({
creation = runOwner.ctx.agents.create({
fresh ids and lineage,
cloned options and optional seed,
setup(childCtx) => install persona, tool restriction, structured runtime
})
returnedRun.started = creation.then(childHandle => publication complete)
returnedRun.result = async:
await returnedRun.started
send the child prompt, await idle, derive the terminal result
SubagentService.start(...):
attach result settlement handlers immediately
await returnedRun.started
emit subagent/start; later emit the buffered or eventual subagent/end
```
Parent teardown reaches `runOwner` by nesting; the provider and returned run handle reach the same node through their explicit disposers.
@@ -687,7 +702,7 @@ The main benefit is one composition model across data, behavior, and lifetime: r
- Plugin authors use the same registration APIs globally and per agent; only the context changes.
- Registry-owned prompt schemas, executable lookup, Code Mode bindings, policy listeners, and UI presentation resolve from the same agent view.
- Create and resume expose no partially configured registry entry during awaited setup.
- Agent disposal revokes scoped contributions after the driver and final session flush have settled.
- Agent disposal revokes scoped contributions after the driver and all final or idle-injection session flushes have settled.
- Structured output composes per child without global mutation or listener-order assumptions.
- Existing unscoped plugins remain deployment-wide contributors and observers.

View File

@@ -4,7 +4,7 @@ Status: implemented
## Problem
Today the agent loop advertises every registered tool to the model as a native 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.
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.
@@ -37,14 +37,14 @@ Three decisions, each elaborated in its own section below:
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. **Builds the bindings**: the bridge owns a **run-scoped `AbortController`** whose signal follows `exec.signal` (an outer cancel propagates in) and which the bridge itself fires the moment the run settles for any reason — completion, program exception, `computeMs`/`maxWallMs` expiry, worker exit. For every visible capability tool, the binding is an async function that (a) checks the run signal before and after, (b) **JSON-normalizes the argument** — a `JSON.parse(JSON.stringify(args))` round-trip, rejecting that one call with a descriptive `Error` when the value does not survive (`BigInt`, circular structures) — because the seam's structured-clone boundary is wider than JSON while the session log accepts only JSON, (c) awaits its turn on the **per-run serialization queue** (below), (d) calls `this.execute({ callId, name, arguments, agent: exec.agent, parent: exec.token, signal: runSignal })` with a deterministic sub-id `` CallId(`${exec.callId}:code:${n}`) ``, (e) appends a `tool/code-dispatch` session event, and (f) maps the result: success → the text-block contents joined as a `string` (non-text blocks become placeholders), `isError` → **the binding rejects** with an `Error` carrying the result text. The child's readonly `parent` is only the outer execution's frozen, property-free token, so commit-style observers can correlate outcomes without receiving a mutation path into the live `run_code` wrapper. Every sub-call still traverses the full pipeline under its own immutable identity and registry-assigned token. The run signal, rather than the bare outer one, lets budget expiry abort an in-flight sub-tool instead of orphaning it. Rejection gives programs ordinary `try/catch` and `Promise.all` failure semantics rather than a bespoke result envelope.
2. **Runs the program**: `ctx.codeRuntime.run({ program: args.code, bindings: [{ global: 'tools', functions }], signal: exec.signal })`.
3. **Surfaces the outcome — after reaching quiescence.** When `ctx.codeRuntime.run()` resolves, the bridge fires the run-scoped abort (cancelling any in-flight sub-dispatch and abandoning queued-unstarted ones), then **awaits the dispatch queue's drain before returning**, per the dispose-to-quiescence rule in [defensive patterns](../../../defensive-patterns.md): an aborted in-flight sub-call still settles and logs its `isError` `tool/code-dispatch` event *inside* the open turn, and nothing can append after `run_code` returns. A successful run then returns one text block — the captured console/stdout output followed by the rendered return value (if any) — plus a `meta` payload (capped logs, dispatch count) for presentation. A run with `result.error` throws a `CodeRunFailedError extends HarnessError` (`code: 'CODE_RUN_FAILED'`, message = the error kind and text plus captured logs so the model can self-correct); the registry's existing catch turns it into a structured `isError` result.
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. **Surfaces the outcome — after reaching quiescence.** When `ctx.codeRuntime.run()` settles, whether by fulfillment or rejection, the bridge fires the run-scoped abort (cancelling any in-flight sub-dispatch and abandoning queued-unstarted ones), then **awaits the dispatch queue's drain before returning or propagating**, per the dispose-to-quiescence rule in [defensive patterns](../../../defensive-patterns.md): an aborted in-flight sub-call still settles and logs its `isError` `tool/code-dispatch` event *inside* the open turn, and nothing can append after `run_code` settles. A successful result then returns one text block — the captured console/stdout output followed by the rendered return value (if any) — plus a `meta` payload (capped logs, dispatch count) for presentation. A fulfilled run with `result.error` throws a `CodeRunFailedError extends HarnessError` (`code: 'CODE_RUN_FAILED'`, message = the error kind and text plus captured logs so the model can self-correct); a backend rejection propagates through the same registry error boundary. Both become structured `isError` tool results.
**Sub-call `additionalContext` is suppressed, deliberately.** A `tools/post-execute` hook may attach `additionalContext` to a call; for loop-dispatched calls the loop buffers those and appends each as a `context/message` only after the step's `tool/result`s, preserving call/result adjacency. A sub-dispatch result's `additionalContext` has no such safe outlet from inside a running `run_code`: injecting immediately would land a `context/message` between the parent's `tool/call` and its `tool/result` (breaking the adjacency the buffering exists to protect), and `PostToolDecision.additionalContext` is singular where a program may produce many. The MVP therefore drops sub-call `additionalContext`, pinned by a test and stated in the hooks bridge's docs; the follow-up (a plural context channel or loop-level sub-dispatch buffering) is deferred until a real hook needs it through Code Mode.
**Concurrency: serialized, enforced by the binding.** The bindings are async, so a model writing `Promise.all([tools.a(…), tools.b(…)])` starts both immediately — concurrent dispatch would be the default, while the tool contract carries no concurrency-safety metadata (the open parallel-execution TODO). Each `run_code` invocation therefore owns a dispatch queue and every binding call chains onto it, so even `Promise.all` executes the underlying `ctx.tools.execute()` calls one at a time in submission order; when the run settles, queued-but-unstarted dispatches are abandoned. Lifting this per tool remains tied to tools declaring themselves concurrency-safe.
**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 `Run code`, `rawInput` = the program text; `presentResult` → a `generic` card whose content is the captured output (from `meta`). Not a `terminal` card: that card's semantics are "a shell command in a working directory", which a program is not.
**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`
@@ -56,7 +56,7 @@ Each sub-dispatch appends one session event, declared by `dsh-tools` via `Sessio
- `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 }`an error is a field on a resolved result, never a rejection of `run()`.
- `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).

View File

@@ -37,7 +37,7 @@ A new package group `packages/subagent/`:
### The primitive: `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) → SubagentRun`. The run carries `started` (the provider's publication/readiness promise), `result` (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 waits for `started` before emitting the paired `subagent/start` / `subagent/end`; an attempt that never establishes a child emits neither lifecycle event. For an in-process backend, readiness means the child is published in `ctx.agents`; for ACP it means the remote session exists.
### Two kinds of optional capability, discovered two ways

View File

@@ -26,9 +26,11 @@ 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/start` (emit) | additionalContext → inject into a live in-process child; a remote child has no local injection target | — (not a Codex event) |
| `subagent/end` (emit) | observe-only | — |
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`.
@@ -52,11 +54,10 @@ Two different cwds, kept distinct on purpose. The hooks **themselves** run in th
## Deferred (faithful-but-degraded)
- **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`** — deferred at landing, since serviced: the [approval seam](2026-07-06-approval-seam.md) resolves `ask` through `ctx.approval` (ACP prompts over `session/request_permission`), degrading to `deny` only where no approval service is composed.
- **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. `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.
- **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, 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 emitted only after child publication, so the bridge can capture the live in-process child synchronously, but the result driver may queue the prompt as that same readiness boundary resolves and a short-lived child can finish before the detached hook injects. Making startup context a gated/awaited primitive is a loop-level change deferred to the interception seams; 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.
## Alternatives considered

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@@ -22,7 +22,7 @@ The canonical surface separates transformable policy, around-dispatch control, a
Every call follows one ordered pipeline: `tools/pre-execute` → monotonic guards → `tools/execute` → core dispatch → `tools/post-execute``tools/result`. The registry requires caller-owned `arguments` to survive lossless-JSON validation before and after cloning, then snapshots `ToolExecutionInput` into a pipeline execution with its own opaque token: identity fields and deeply frozen detached arguments are immutable for the whole pipeline, and a nested call's `parent` contains only the enclosing execution's token rather than its live object. Optional `signal` is the only operational field an around-dispatch wrapper may add, replace, or remove, and the complete object freezes before final observers run. This identity contract prevents a policy listener from silently changing what the log, UI, and tool body believe ran.
- **`tools/pre-execute`** is the extensible waterfall gate. Its `PreToolDecision` allows, denies, or asks; deny/ask skips `tools/execute` and core dispatch but still produces a normalized result for post-policy and final observers.
- **`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 `additionalContext`; in-place mutation of the result is not a transform channel, because the registry rebuilds the outcome from a protected snapshot plus the returned decision.
@@ -46,7 +46,7 @@ Core dispatch and the tool body sit inside normalization boundaries, so tool, li
### Boundaries
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 permission/`ask` system has since landed as the [approval seam](2026-07-06-approval-seam.md), whose `ctx.approval` services the `ask` this RFC originally shipped degraded to deny; terminal monotonic stopping is now provided separately by `agent/turn-stop`.
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

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@@ -12,7 +12,7 @@ This RFC enriches the end payload. It is deliberately **observe-only**: no contr
**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`.
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**. The service waits for `run.started` before firing `subagent/start`; an in-process listener can therefore reach the published child via `ctx.agents.get(info.id)` and `inject()` into it, while a remote provider need not have a local registry entry. It observes `run.result` immediately, snapshots the end payload before the caller can mutate it, and emits `subagent/end` only after start; readiness rejection emits neither event. The callbacks remain observe-only and per-listener containment keeps one bad subscriber from stranding a live run, surfacing as an unhandled rejection, or starving later listeners.
## Alternatives considered

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@@ -4,7 +4,7 @@ Status: implemented
## Problem
Two callers need to put one question — "may this specific action proceed?" — to a human, and neither has a channel. `tools/pre-execute`'s `ask` decision (produced today by the Claude-Code hook bridge's `permissionDecision: ask`) degrades to deny because nothing services it. The [sandbox RFC](2026-07-06-sandbox.md)'s escalation phase needs the same channel for its post-denial one-shot retry. Without a shared seam, each would invent its own outcome vocabulary, UI routing, cancellation, and audit trail — and a deployment with no UI at all needs a guarantee that an unanswerable question can never grant anything.
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).
@@ -14,7 +14,7 @@ One package, `dsh-user-approval` (`packages/ui/user-approval`), owning the vocab
### How a deployment uses it
One `cordis.yml` entry mounts the seam; not loading it is the opt-out consumers degrade to their historical fail-closed behavior with zero approval code registered:
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
@@ -49,29 +49,29 @@ The `escalation-rejected` twin ends in `{"outcome": "rejected"}` instead: nothin
#### The seam: mechanism and policy split
`ApprovalService.request(req)` always resolves to a closed `ApprovalOutcome``allowed-once` / `rejected` / `cancelled` / `unavailable` — and never rejects. The service is the mechanism: it dispatches the `approval/request` waterfall, races the request's `AbortSignal` (abort settles `cancelled`; a late answer is discarded, never double-audited), contains a throwing answerer as `unavailable`, normalizes a rogue non-vocabulary return to `unavailable`, and lands the log-only audit pair `approval/asked`/`approval/decided` (paired by the branded `ApprovalRequestId`) on the requesting agent's session log. Grants are one-shot by definition: `allowed-once` authorizes the single asked-about action, never a class of future ones, and the service stores nothing between requests. The one precondition: `request()` throws (before appending anything) when the agent's session has no open turn — the audit pair must be turn-enclosed, the turn being the durable log's commit/replay boundary (a bare event between turns is dropped as crash tail on reload); every shipped ask path runs mid-turn already, and idle asks are a deferred design.
`ApprovalService.request(req)` always resolves to a closed `ApprovalOutcome``allowed-once` / `rejected` / `cancelled` / `unavailable` — and never rejects. The service synchronously snapshots and shallow-freezes the accepted request before its first asynchronous boundary: scalar fields are copied while the agent and `AbortSignal` remain exact identity capabilities, so later caller mutation cannot redirect scope, payload, cancellation, or either audit event. The service dispatches the `approval/request` waterfall, races the captured signal (abort settles `cancelled`; a late answer is discarded, never double-audited), contains a throwing answerer as `unavailable`, normalizes a rogue non-vocabulary return to `unavailable`, and lands the log-only audit pair `approval/asked`/`approval/decided` (paired by the branded `ApprovalRequestId`) on the captured agent's captured session log. A session observer runs after an event enters the append-only log; if one throws, the service recognizes the recorded event, contains the callback failure, and completes the pair. Grants are one-shot by definition: `allowed-once` authorizes the single asked-about action, never a class of future ones, and the service stores nothing between requests. The one precondition: `request()` throws (before appending anything) when the agent's session has no open turn — the audit pair must be turn-enclosed, the turn being the durable log's commit/replay boundary (a bare event between turns is dropped as crash tail on reload); every ask path runs mid-turn already, and idle asks are a deferred design.
Answerers are the policy, and they are `approval/request` waterfall listeners. The waterfall buys exactly what the seam needs: with zero listeners the dispatch falls through to the caller-supplied default — `unavailable`, so fail-closed needs no configuration and no code in any deployment; a listener that recognizes the request's agent answers by returning an outcome without calling `next()` (the decision slot is single-occupancy, first answer wins — the same documented semantics as the `fs/write-intent` gate); a listener that does not recognize the agent MUST delegate via `next()` so another answerer or the default gets the question; and listeners dispose with their owning fiber, so an unloaded UI plugin degrades the next ask to `unavailable` instead of leaving a dangling channel. Registration order across sibling plugins is not load-order deterministic (the loader starts siblings concurrently), so a deployment composes ONE terminal answerer and reserves `prepend` listeners for decide-or-delegate gates.
`ApprovalRequest` carries the asking `agent` (routes the question; receives the audit events), the `toolName`, the optional exact `callId`, the asker's human-readable `reason`, and the optional `signal`. The vocabulary is deliberately self-contained — it names the tool-call by the `CallId` brand from `dsh-llm` and never imports `dsh-tools` — because `dsh-tools` depends on `dsh-user-approval` (the ask routing) and a `ToolCallView` import would close a package cycle. It deliberately does NOT carry tool arguments: a UI answerer attaches the prompt to the already-streamed tool call via `callId` instead of re-rendering the call.
`ApprovalRequest` carries the asking `agent` (routes the question; receives the audit events), the `toolName`, the optional exact `callId`, the asker's human-readable `reason`, and the optional `signal`. The caller owns this input record; `request()` owns its frozen acceptance snapshot. The vocabulary is deliberately self-contained — it names the tool-call by the `CallId` brand from `dsh-llm` and never imports `dsh-tools` — because `dsh-tools` depends on `dsh-user-approval` (the ask routing) and a `ToolCallView` import would close a package cycle. It deliberately does NOT carry tool arguments: a UI answerer attaches the prompt to the already-streamed tool call via `callId` instead of re-rendering the call.
#### Ask routing in dsh-tools
`ToolRegistry.execute()` resolves an `ask` decision through the seam before the shared deny path: `allowed-once` proceeds to dispatch, and the three non-grants deny with distinct reasons — "the user rejected…", "…was cancelled", "…no approval channel is available" — so the model can tell a human "no" from an absent channel. The seam is consumed opportunistically (`ctx.get('approval')`, the `tool-bash`/`agent-loop` pattern), not statically injected: a deployment that composes no ApprovalService keeps the historical ask→deny degrade verbatim, an unmount mid-session degrades the same way on the next ask, and the registry's fiber never gates on the seam's presence. An agent-less execution also degrades — without an agent there is no session to audit to and no UI to route to.
`ToolRegistry.execute()` resolves an `ask` decision through the seam before the shared deny path: `allowed-once` proceeds to guards and dispatch, and the three non-grants deny with distinct reasons — "the user rejected…", "…was cancelled", "…no approval channel is available" — so the model can tell a human "no" from an absent channel. The seam is consumed opportunistically (`ctx.get('approval')`, the `tool-bash`/`agent-loop` pattern), not statically injected: with no ApprovalService, or after one unmounts, the next ask fails closed without gating the registry's fiber. An agent-less execution also fails closed — without an agent there is no session to audit to and no UI to route to.
#### The per-session policy tier
The seam also owns the session-scoped approval policy — the approval knob of the two-knob per-session switching design ([the sandbox RFC](2026-07-06-sandbox.md) § Per-session modes is the pattern's home: one log-only event per knob, a pure fold, THE write path, ACP config-option advertisement, and turn-anchoring). `ApprovalPolicy` is `'ask' | 'never'`, and `effectiveApprovalPolicy(events) ?? Config.policy` (default `'ask'`) decides every request BEFORE any interactive answerer: the service resolves a `'never'` session to `'rejected'` INSIDE `request()`, before dispatching the waterfall at all — no listener registration, including a later `prepend`, can sit ahead of it — while `'ask'` dispatches unchanged (fail-closed `'unavailable'` with nobody composed, exactly the prior behavior). Visibility follows the switching design's two layers with one asymmetry: the prompt section states ONLY `'never'` (deterministic, availability-independent — "you will be prompted" would overclaim in a composition with no answerer, and absence under a logged header is exactly how the narrator reads `'ask'` back), the narrator injects at most one coalesced notice per switch, and the audit pair still lands on every ask, including the policy's auto-rejections.
The seam also owns the session-scoped approval policy — the approval knob of the two-knob per-session switching design ([the sandbox RFC](2026-07-06-sandbox.md) § Per-session modes is the pattern's home: one log-only event per knob, a pure fold, THE write path, ACP config-option advertisement, and turn-anchoring). `ApprovalPolicy` is `'ask' | 'never'`, and `effectiveApprovalPolicy(events) ?? Config.policy` (default `'ask'`) decides every request BEFORE any interactive answerer: the service resolves a `'never'` session to `'rejected'` INSIDE `request()`, before dispatching the waterfall at all — no listener registration, including a later `prepend`, can sit ahead of it — while `'ask'` dispatches unchanged and falls through to fail-closed `'unavailable'` when nobody answers. Visibility follows the switching design's two layers with one asymmetry: the prompt section states ONLY `'never'` (deterministic, availability-independent — "you will be prompted" would overclaim in a composition with no answerer, and absence under a logged header is exactly how the narrator reads `'ask'` back), the narrator injects at most one coalesced notice per switch, and the audit pair still lands on every ask, including the policy's auto-rejections.
#### The ACP answerer
The bridge registers the first real answerer: it resolves the owning session through its existing `WeakMap<Agent, sessionId>` reverse map, issues `session/request_permission` with the request's `callId` as the `toolCall` reference and the one-shot options `allow_once`/`reject_once`, and maps the response — selected `allow-once``allowed-once`, any other selection → `rejected` (an unknown optionId from a non-conforming client never grants), client `cancelled``cancelled`. A request for a foreign agent — or one without a `callId`, since the protocol prompt must attach to a tool call — delegates via `next()`. A rejected RPC (client gone mid-prompt) propagates to the service, which contains it as `unavailable`. Whether a call ASKS at all is policy — a hook or `tools/pre-execute` plugin returning `ask` — never the bridge's own judgment.
The reverse-map ownership seam [the ACP support RFC](../../implemented/feature/2026-06-14-acp-agent-client-protocol.md) laid down is exactly what the answerer routes through, and per-session permission ownership (the blocker recorded in [the multi-session RFC](../../implemented/feature/2026-06-14-acp-multi-session.md)) is what it implements.
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` / `approval/decided` are log-only session events (the `hook/invoked`/`hook/result` precedent): durable, replayable, never in the model transcript. The model's entire view of an approval is the tool result the asker derives from the outcome — reconstructability holds because that result is an ordinary logged `tool/result`. One `decided` per `asked`, whatever the outcome, including an already-aborted signal (settled `cancelled` without dispatching) and a contained answerer failure.
`approval/asked` / `approval/decided` are log-only session events (the `hook/invoked`/`hook/result` precedent): durable, replayable, never in the model transcript. The model's entire view of an approval is the tool result the asker derives from the outcome — reconstructability holds because that result is an ordinary logged `tool/result`. One `decided` lands per `asked`, whatever the outcome, including an already-aborted signal (settled `cancelled` without dispatching), a contained answerer failure, or a session observer that throws after either event is already appended.
#### Entities and dependencies
@@ -79,35 +79,35 @@ One package, no cycles: `dsh-user-approval` peers on `cordis`, `dsh-session` (ev
### Testing
Unit tier: the service's outcome branches (fail-closed default, first-wins slot, delegation, containment, rogue-value normalization, abort-before and abort-during with late-answer discard, fresh ids, fiber-disposal degradation) and the policy tier (both values × dispatch/decide, a `'never'` decision unbypassable even by an answerer prepended AFTER the service, audit pair intact) in `dsh-user-approval`; the ask routing matrix (grant dispatches; three non-grant reasons pinned verbatim; unmounted and agent-less degrades; the registry's own exhaustiveness backstop against a non-conforming stand-in) in `dsh-tools`; the answerer (wire shape of the prompt, outcome mapping, unknown-option conservatism, foreign-agent and call-less delegation) driven through a real bridge + scripted client in `dsh-acp`.
Unit tier: the service's outcome branches (fail-closed default, first-wins slot, delegation, containment, rogue-value normalization, abort-before and abort-during with late-answer discard, fresh ids, fiber-disposal degradation), accepted-request mutation across agent scopes, post-append observer throws on both audit events, and the policy tier (both values × dispatch/decide, a `'never'` decision unbypassable even by an answerer prepended AFTER the service, audit pair intact) in `dsh-user-approval`; the ask routing matrix (grant dispatches; three non-grant reasons pinned verbatim; unmounted and agent-less degrades; the registry's own exhaustiveness backstop against a non-conforming stand-in) in `dsh-tools`; the answerer (wire shape of the prompt, outcome mapping, unknown-option conservatism, foreign-agent and call-less delegation) driven through a real bridge + scripted client in `dsh-acp`.
Snapshot tier: the harness accepts scripted permission answers (`permissionAnswers` in a scenario's `input.json`, consumed FIFO; an unscripted prompt answers `cancelled`, fail closed). The seam's wire is recorded end to end in the sandbox example's suite: both escalation branches drive `session/request_permission` through this seam over scripted answers (grant and rejection), and the recorded `mode-switching` scenario pins the `'never'` prompt sentence and the policy-switch notice ([the sandbox RFC](2026-07-06-sandbox.md) § Testing).
## 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-driven `ask` scenario** — the wire is recorded via the sandbox example's escalation branches; the hook-producer variant stays on the unit tier and the hook matrix's `hook-cc-pretool-ask`, with its deny texts pinned verbatim there.
- **Routing a child agent's approvals to the parent session** — `subagent-acp`'s child today auto-answers its own `permission` requests; surfacing them to the parent's editor is its own design.
- **A recorded hook-driven `ask` through a composed answerer** — the human-prompt wire is recorded through the sandbox example's escalation branches. The hook matrix's `hook-cc-pretool-ask` pins the no-ApprovalService fallback denial, while the hook-producer-plus-answerer composition remains on the unit tier.
- **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.
- **[The ACP support RFC](../../implemented/feature/2026-06-14-acp-agent-client-protocol.md)'s inline `tools/pre-execute` permission gate** — rejected, and superseded by this seam: 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 hooks' `ask` — the vocabulary the interception seams already ship — unserviced.
- **A generic user-interaction seam (`ctx.userInteraction`) instead** — rejected: 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. The generic seam has since shipped (`packages/ui/user-interaction`, the `ask_user_question` tool over ACP elicitation) and approval deliberately still does not ride it — 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.
- **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
What shipped pins — the suites in Testing hold each:
The implemented contract is pinned by the suites in Testing:
- With an ApprovalService and an answerer composed, a hook's `ask` reaches a human and `allowed-once` dispatches the tool; every other outcome denies with its distinct reason.
- A `'never'` session auto-rejects every ask without prompting anyone, states the policy in its prompt, and narrates switches (the shared switching mechanics are pinned in [the sandbox RFC](2026-07-06-sandbox.md)).
- Every unanswerable path fails closed to `unavailable`: no service (degrade, verbatim historical text), no listener, a foreign or agent-less request, a throwing answerer, a rogue return value, a dead client connection.
- Every `request()` lands exactly one `approval/asked`/`approval/decided` pair on the asking agent's log, replayable, invisible to the model transcript.
- Every unanswerable path fails closed to `unavailable`: no service, no listener, a foreign or agent-less request, a throwing answerer, a rogue return value, or a dead client connection.
- Every `request()` snapshots its routing identity and lands exactly one `approval/asked`/`approval/decided` pair on that agent's captured log, replayable and invisible to the model transcript; post-append observer failures cannot split the pair.
- Prompts route per-session through the bridge's ownership map; one session's prompt can never reach another session's editor.
- A deployment that composes nothing new behaves byte-identically (the snapshot suite's goldens are unchanged).
- A deployment with no ApprovalService emits no approval prompt or approval audit events and denies every `ask` request.
Costs and accepted limits:
@@ -125,7 +125,7 @@ Behavioral and usage questions only — every "why not X?" design question lives
- **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 unanswerable today by design. `subagent-acp`'s child-side auto-answer is untouched; routing a child's asks to the parent's editor is deferred (§ Deferred).
- **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.