Review follow-up (tianyicui): plan mode and the sandbox are orthogonal
AXES, not just orthogonal state — entering plan must not change what the
sandbox enforces, matching Codex's separation of Plan/Default
collaboration presets from sandbox and approval settings.
ModeDefinition.access, the bash/resolve-mode clamp, and both cap-derived
guards are removed; a ModeDefinition is exactly { section }, and a mode
now carries only its guidance section plus the exit_plan_mode review.
The bash seam's resolveMode + waterfall go with their only listener:
dsh-bash and dsh-tool-bash revert to master byte-for-byte, and the
dsh-mode → dsh-bash dependency edge is gone. A deployment that wants
kernel-enforced read-only planning pairs the mode picker with the
independent sandbox-mode option, in either order.
The RFC archives this as the second removed enforcement shape (after
the interim allowlist) with the same restart trigger — effects
self-declaration; the orthogonality FAQ now answers with the two-axis
rule. The plan example demonstrates the axes side by side, and the
re-recorded fixtures pin the guidance-only section.
@@ -113,7 +113,7 @@ Every product feature maps to a listener on a documented extension seam — the
| Monotonic terminal turn policy | return `{ action: 'stop' }` from serial `agent/turn-stop`, after continuation and steering have already been folded |
| Subprocess sandbox (landlock / sandbox-exec) | use a `ctx.sandbox` backend through `dsh-bash-sandbox`; use `tools/pre-execute` for capability-level denial |
| Permission system / AskUserQuestion | return `ask` from `tools/pre-execute` and answer through `ctx.approval`; register a separate model-facing ask tool for ordinary user questions |
| Plan mode | Shipped: [`@deepseek-ai/dsh-mode`](../../packages/mode/mode/README.md) — the logged `mode/set` state, the `mode:policy` guidance section, the sandbox `access` cap (a `bash/resolve-mode` clamp + cap-derived bash guards), and the user-reviewed `exit_plan_mode` exit |
| Plan mode | Shipped: [`@deepseek-ai/dsh-mode`](../../packages/mode/mode/README.md) — the logged `mode/set` state, the `mode:policy` guidance section, and the user-reviewed `exit_plan_mode` exit; enforcement stays on the independent sandbox/approval axes |
| Sub-agent delegation | the `ctx.subagents` provider registry (`dsh-subagent-spawn`/`-fork`/`-acp`) + `dsh-tool-subagent` exposing one configured provider to the model |
| MCP | one plugin per server: discover tools → `ctx.tools.register()` |
Waterfall around BashExecutor.resolveMode's base — the session's standing override falling back to the executor's configured default. A policy plugin narrows the resolution per call by clamping `await next()` (a session mode's `access` cap is the shipped example); returning without `next()` replaces the resolution outright. Dispatched only for a confining executor — a never-confining one resolves `undefined` without consulting listeners, so a listener always receives a real base mode from `next()`.
`ctx.modes`: the session-mode service. Owns the `mode/set` vocabulary, the pending-intent flush, the boundary narration, and both policy layers (the assemble filter + `mode:policy` section, and the `tools/pre-execute` gate). UIs read mode flips off `session/event`; there is no live mirror.
`ctx.modes`: the session-mode service. Owns the `mode/set` vocabulary, the pending-intent flush, the boundary narration, the `mode:policy` section, and the exit tool's visibility rule. UIs read mode flips off `session/event`; there is no live mirror.
@@ -10,11 +10,11 @@ Every shipped plan mode decomposes into the same five parts — a low-authority
## Decision
The deliverable is **plan mode**. It ships as the first **session mode** — a named, logged, per-agent policy state: mode definitions — the guidance section the model sees, the sandbox access cap — are deployment config, and the mode IN FORCE for an agent is session state, folded from its log. One new product package, `@deepseek-ai/dsh-mode` at `packages/mode/mode/` (a new top-level group, the `packages/approval/` shape), owns the event vocabulary, a thin `ctx.modes` service, and every policy listener; the loop does not change. `plan` is the only shipped definition — the mode-shaped vocabulary exists so a second mode never renames durable event types, not because more modes ship now.
The deliverable is **plan mode**. It ships as the first **session mode** — a named, logged, per-agent COLLABORATION state: a mode definition is the guidance section the model sees, deployment config; the mode IN FORCE for an agent is session state, folded from its log. Modes are one axis and the enforcement knobs — the sandbox mode, the approval policy — are others: they never read or write each other, matching how Codex keeps its Plan/Default collaboration presets separate from its sandbox and approval settings. One new product package, `@deepseek-ai/dsh-mode` at `packages/mode/mode/` (a new top-level group, the `packages/approval/` shape), owns the event vocabulary, a thin `ctx.modes` service, and every policy listener; the loop does not change. `plan` is the only shipped definition — the mode-shaped vocabulary exists so a second mode never renames durable event types, not because more modes ship now.
The state is one `SessionEventMap` member: **`mode/set`**, a log-only, non-surface event carrying `{ mode: string }` with whole-value-replace semantics, plus a pure `foldMode(events)` that returns the mode in force — the last `mode/set`, or the default mode when none exists. Because [the log is the fact channel](../../implemented/architecture/2026-06-30-event-domain-semantics.md), resume, fork, and compaction restore the mode with no extra machinery, and UIs read flips off `session/event`. The default mode is the absence of policy — no section, no filtering, no gate — so an agent that never sees a `mode/set` behaves byte-identically to a deployment that never loads `dsh-mode`, which keeps every existing snapshot golden stable and makes the plugin safe to compose unconditionally.
Enforcement is deliberately scoped to where an enforcer exists. The **soft** surface is a `system-prompt/assemble` listener that renders the mode's guidance section and shows the `exit_plan_mode` tool IFF the folded mode is `plan` — every transition therefore surfaces as an attributable `request/header` event on the next step (a delta when expressible, the full fallback snapshot otherwise), keeping the [reconstructability](../../implemented/architecture/2026-07-05-reconstructable-requests.md) invariant green by construction. The **enforced** surface is the mode's `access` cap on the bash seam: a `bash/resolve-mode` clamp that keeps every shell command inside the declared sandbox access, plus two cap-derived `tools/pre-execute` guards (the bash tools are withheld when no confining executor can honor the cap; sandbox escalation is denied while the cap holds). There is NO general tool allow/deny list — which tools a mode admits is an effects question, parked until tool definitions declare their effects ([Deferred](#deferred)); until then a mode's non-shell restraint is the section's guidance.
A mode's whole surface is soft: a `system-prompt/assemble` listener renders the mode's guidance section and shows the `exit_plan_mode` tool IFF the folded mode is `plan` — every transition therefore surfaces as an attributable `request/header` event on the next step (a delta when expressible, the full fallback snapshot otherwise), keeping the [reconstructability](../../implemented/architecture/2026-07-05-reconstructable-requests.md) invariant green by construction. A mode deliberately enforces NOTHING: no execution gate, no tool filtering, no reach into the sandbox or approval knobs — a user who wants a hard read-only floor while planning switches the sandbox-mode option beside the mode picker, in either order, and neither axis disturbs the other. There is likewise NO per-mode tool allow/deny list — which tools a mode admits is an effects question, parked until tool definitions declare their effects ([Deferred](#deferred)); a mode's restraint is its section's guidance plus the exit review.
The model leaves plan mode through the **`exit_plan_mode`** tool: its single argument is the plan text, which makes the plan a durable log artifact, and the tool conducts the review itself through the user-interaction seam — a question with options and a free-text channel, not a bare permission — so an approval flips the logged mode back to the default, and a rejection becomes the corrective error carrying the user's feedback verbatim, which keeps the model planning with direction. A user flips the mode from any surface through `ctx.modes.set()`; the flip is applied at the next turn boundary (session events are turn-enclosed) and narrated to the model once, only when the model-visible state actually changed.
@@ -24,11 +24,11 @@ The model leaves plan mode through the **`exit_plan_mode`** tool: its single arg
The user switches the session to plan mode — the ACP mode picker or the stdio `/mode plan` — and from the next turn every request ships the plan guidance section and the `exit_plan_mode` tool.
The model explores and designs — the bash tools clamped to a read-only sandbox by plan mode's `access` cap when the composition confines them, so exploration commands run for real while a write is denied by the sandbox itself; outside the shell, the section's guidance is what defers changes into the plan.
The model explores and designs; the section's guidance is what defers changes into the plan. The sandbox and approval knobs keep whatever the user set them to — a deployment (or user) that wants kernel-enforced read-only during planning pairs plan mode with the independent sandbox-mode option.
When ready, the model calls `exit_plan_mode` with the plan markdown as its argument; the UI renders the plan as the call card and the review question arrives through the user-interaction channel — approve, or keep planning, with free-text feedback welcome — so what the human reviews is exactly the logged artifact.
On approve, the tool flips the logged mode back to the default: the next step runs unclamped with the narrowing-back header event in the log, and execution tracking from there is already `todo_write`'s job. On keep-planning, the model receives a corrective error carrying the user's feedback text, revises, and re-presents.
On approve, the tool flips the logged mode back to the default: the next step drops the plan section and the exit tool (the header event is in the log), and execution tracking from there is already `todo_write`'s job. On keep-planning, the model receives a corrective error carrying the user's feedback text, revises, and re-presents.
### Deployment configuration
@@ -43,10 +43,9 @@ Mode definitions are validated plugin Config — per repo convention, changeable
section:|
You are in plan mode: explore and design, then present the
plan for approval through exit_plan_mode.
access:read-only
```
A definition is exactly `{ section, access? }`. The shipped `plan` pairs its guidance section with `access: read-only` ([the access cap](#the-access-cap-clamping-the-bash-resolution)); there is deliberately no per-mode tool list ([FAQ](#faq)). `default` is reserved (the absence of policy) and rejected as a key; an `access` outside the `SANDBOX_MODES` ladder — or any unknown definition key, a `tools` list included — fails validation at load; an unknown mode name fails loudly at `set()` time.
A definition is exactly `{ section }` — there is deliberately no per-mode tool list and no enforcement field ([FAQ](#faq)). `default` is reserved (the absence of policy) and rejected as a key; any unknown definition key — a `tools` list or an `access` cap included — fails validation at load; an unknown mode name fails loudly at `set()` time.
### In the terminal
@@ -75,16 +74,13 @@ The payload carries no reason/provenance field: a tool-driven flip sits next to
resolveConfig(config): ResolvedModes // explicit resolve (the dsh-bash template), fail-loud:
// 'default' as a key rejected; access validated against
// the SANDBOX_MODES ladder; any unknown key rejected
// 'default' as a key rejected; any unknown key rejected
```
The two-field shape is deliberate minimalism, not the final vocabulary: a per-tool policy dimension returns as effects metadata on tool definitions ([Deferred](#deferred)), read here rather than re-declared per mode — the config shape must not need a migration when it arrives.
The one-field shape is deliberate minimalism, not the final vocabulary: a per-tool policy dimension returns as effects metadata on tool definitions ([Deferred](#deferred)), read here rather than re-declared per mode — the config shape must not need a migration when it arrives.
### The fold, the service, and the flush
@@ -96,54 +92,31 @@ Contained listeners on the loop's interception seams ([defensive patterns](../..
A `system-prompt/assemble` waterfall listener reads the calling agent's mode (the `AssembleContext` carries `agent`) and, in a non-default mode, appends the mode's guidance section. The loop already renders per step and logs the result: entering or leaving a mode surfaces on the next step as a `request/header-delta` — or as the full `request/header` fallback snapshot when the change is inexpressible in the delta encoding (adding `exit_plan_mode` is a front-of-list insertion with no delta form; removing it on exit is a pure removal and DOES delta) — so every mode transition is an attributable log fact. The section is static per mode and the plan itself stays in the conversation (messages and tool args, already in context), so a mode does not add per-step prompt churn — re-injecting plan state into every request ([Prior art](#prior-art)'s compaction-survival hack) is unnecessary and would only burn prefix cache.
The guidance section is an ordinary registered section, `{ name: 'mode:policy', order: 50, text: context => … }` — order 50 sits after the persona (0) and before tool guidance (100–199); it resolves to the folded mode's configured text and to `''` (dropped at render) for the default mode or an agent-less assembly. The same listener carries the one tool filter left, deliberately narrow (`prepend: true`, so it wraps outside every append-registered listener's post-`next()` mutation): `exit_plan_mode` is visible IFF the agent's folded mode is `plan` — which keeps a default-mode assembly byte-identical to a no-`dsh-mode` deployment even though the tool is always registered — and the bash trio is hidden while an access cap cannot be honored ([the access cap](#the-access-cap-clamping-the-bash-resolution)). Foreign additions pass through untouched: which tools a mode admits is not this plugin's decision. Code Mode's soft surface is the `tools:sdk` section rather than the wire schemas, and section text resolves in assemble's base, so the same wrapper re-renders that section under the same visibility rule; the default mode re-renders it too, hiding only the exit binding, keeping a default-mode Code Mode assembly byte-identical to a deployment that never loaded `dsh-mode`.
### The cap-derived guard at `tools/pre-execute`
The one execution-phase listener is scoped to the `access` cap; without a declared cap (or in the default mode, or for an agent-less call) every call passes through. It exists because [`ToolRegistry.execute()`](../../../../packages/core/tools/README.md) dispatches any registered tool by name — the assemble filter alone cannot stop a hallucinated call to a hidden bash tool, and neither surface may let a capped mode run an unconfinable shell.
```text
tools/pre-execute: no exec.agent → next() // agent-less calls have no session to fold
folded mode default / no access → next()
name not in {bash, bash_output, bash_kill} → next()
no confining executor → deny // the cap cannot be honored; never run unconfined
name = bash with sandbox_permissions → deny // no widening mid-mode; plan the step instead
otherwise → next() // the clamp (below) confines execution
```
The guard folds the LOGGED mode only, never the pending intent — enforcement judges by the same state the request's header shipped under. It never returns `{ kind: 'ask' }`: the exit review is a question with options and feedback, not a permission, so it lives inside the tool's own execution over the user-interaction seam and the registry's `ask` vocabulary stays free for genuine permission gating. A call to `exit_plan_mode` outside plan mode is rejected by the tool's own folded-mode recheck.
### The access cap: clamping the bash resolution
A definition's `access` is the widest sandbox access shell commands run under while the mode is in force — the `SANDBOX_MODES` ladder from `dsh-bash` (`read-only` | `workspace-write` | `danger-full-access`); the built-in `plan` ships `access: 'read-only'`. The cap is made real on the bash seam's own resolution point: `BashExecutor.resolveMode(session)` computes `session override ?? executor default` and dispatches it through the **`bash/resolve-mode` waterfall** (declared in `dsh-bash`; consulted by `dsh-tool-bash` at both its stamping site and its escalation baseline), and `dsh-mode` registers the clamp listener — `min(await next(), access)` on the ladder, per call.
The composition is read-time over two independent log folds. The session's sandbox knob (`bash/sandbox-mode` events, the sandbox RFC) is never written by the mode: a knob flipped during plan stays logged but capped, exiting plan uncovers it unchanged, the two switch in any order without interference, and there is no restore step for a crash to strand. Attribution stays log-adjacent on both axes — a clamped call's width is explained by the standing `mode/set`, a knob change by its own `bash/sandbox-mode` event.
Two rules ride with a declared cap. The bash trio (`bash`/`bash_output`/`bash_kill`) is CONDITIONAL: both surfaces admit it only while a confining executor is mounted (`ctx.get('bash')?.sandboxMode` set) — an unconfinable shell cannot honor the cap, so under `dsh-bash-local` the trio is hidden by the filter and denied by the guard. And sandbox ESCALATION is denied at the guard: a `bash` call carrying `sandbox_permissions` in a capped mode gets a deny that points the model at putting the widened step in the plan — without this rule the clamped resolution would read as a legitimate escalation baseline and one approval prompt could pierce the cap mid-mode. A mode without `access` gets neither rule — its shell is the deployment's explicit uncapped choice.
The guidance section is an ordinary registered section, `{ name: 'mode:policy', order: 50, text: context => … }` — order 50 sits after the persona (0) and before tool guidance (100–199); it resolves to the folded mode's configured text and to `''` (dropped at render) for the default mode or an agent-less assembly. The same listener carries the ONE tool rule this plugin has, deliberately narrow (`prepend: true`, so it wraps outside every append-registered listener's post-`next()` mutation): `exit_plan_mode` is visible IFF the agent's folded mode is `plan` — which keeps a default-mode assembly byte-identical to a no-`dsh-mode` deployment even though the tool is always registered. Everything else passes through untouched: which tools a mode admits is not this plugin's decision. Code Mode's soft surface is the `tools:sdk` section rather than the wire schemas, and section text resolves in assemble's base, so the same wrapper re-renders that section under the same visibility rule; the default mode re-renders it too, hiding only the exit binding, keeping a default-mode Code Mode assembly byte-identical to a deployment that never loaded `dsh-mode`. There is NO `tools/pre-execute` listener: a mode gates nothing (the exit tool's own folded-mode recheck rejects an out-of-plan call), and the registry's `ask` vocabulary stays free for genuine permission gating — the exit review is a question with options and feedback, not a permission, so it lives inside the tool's own execution over the user-interaction seam.
### `exit_plan_mode`
`defineTool` with one required `plan: string` argument — the plan is thereby a durable, replayable log artifact riding the ordinary `tool/call` event. `execute` rejects an agent-less call (the [`todo_write` precedent](../../implemented/feature/2026-06-29-todo-write-tool.md)), re-checks the folded mode as defense in depth, then conducts the review: one single-select `ctx.userInteraction.ask()` question — approve, or keep planning — with the free-text channel open for feedback. Approve records the switch back to `default` as a SILENT boundary-applied pending intent (flushed at this step's end, still in-turn) and returns a short confirmation; the plan policy — the sandbox clamp, the exit tool's visibility — therefore keeps holding for every remaining call of the SAME assistant response (they were requested under the plan-shaped header), and the next step runs unclamped, logging the pure-removal header-delta. Every other outcome — keep-planning (the user's feedback text carried verbatim), an aborted question, a missing provider — returns the corrective `isError` that tells the model to revise and re-present, and the mode stays `plan`.
`defineTool` with one required `plan: string` argument — the plan is thereby a durable, replayable log artifact riding the ordinary `tool/call` event. `execute` rejects an agent-less call (the [`todo_write` precedent](../../implemented/feature/2026-06-29-todo-write-tool.md)), re-checks the folded mode as defense in depth, then conducts the review: one single-select `ctx.userInteraction.ask()` question — approve, or keep planning — with the free-text channel open for feedback. Approve records the switch back to `default` as a SILENT boundary-applied pending intent (flushed at this step's end, still in-turn) and returns a short confirmation; the plan surface — the section, the exit tool's visibility — therefore keeps holding for every remaining call of the SAME assistant response (they were requested under the plan-shaped header), and the next step reflects the exit, logging the pure-removal header-delta. Every other outcome — keep-planning (the user's feedback text carried verbatim), an aborted question, a missing provider — returns the corrective `isError` that tells the model to revise and re-present, and the mode stays `plan`.
Its [render intent](../../implemented/architecture/2026-07-02-tool-render-intent-union.md), decided up front: `presentCall` is a `generic` card titled by the plan's first heading with the plan markdown as content, plus a `generic` result card — the review question arrives beside this already-streamed card, so what the human reviews is exactly the logged artifact. The seam is consumed opportunistically (`ctx.get('userInteraction')`), so `dsh-mode` composes without it and degrades to the manual exit pinned in the [FAQ](#faq).
### Dependencies and surfaces
`dsh-mode` is one product package, not a capability-seam trio ([Alternatives considered](#alternatives-considered)): it peers on `cordis`, `dsh-session`, `dsh-agent`, `dsh-tools`, `dsh-system-prompt`, and `dsh-bash` (the `SANDBOX_MODES` vocabulary and the `bash/resolve-mode` clamp listener; the executor itself is read opportunistically via `ctx.get('bash')`, so the composition works without one), injects `['tools', 'systemPrompt']`, reads `ctx.userInteraction` opportunistically at execute time (a type-only peer edge on `dsh-user-interaction`), and depends on no UI package. Beyond the `ctx.modes` call surface everything participates through listeners, so dropping the package gracefully removes modes rather than breaking a consumer. The stdio app adds a `/mode [name]` line-handler branch — the exit review needs nothing there, because the stdio user-interaction provider already owns the prompt queue. The ACP wire mapping is pinned in [High-level API](#over-acp); package-wise the bridge takes a type-only peer edge on `dsh-mode` and reads the service opportunistically, so a bridge without the plugin behaves exactly as today.
`dsh-mode` is one product package, not a capability-seam trio ([Alternatives considered](#alternatives-considered)): it peers on `cordis`, `dsh-session`, `dsh-agent`, `dsh-tools`, and `dsh-system-prompt`, injects `['tools', 'systemPrompt']`, reads `ctx.userInteraction` opportunistically at execute time (a type-only peer edge on `dsh-user-interaction`), and depends on no UI package. Beyond the `ctx.modes` call surface everything participates through listeners, so dropping the package gracefully removes modes rather than breaking a consumer. The stdio app adds a `/mode [name]` line-handler branch — the exit review needs nothing there, because the stdio user-interaction provider already owns the prompt queue. The ACP wire mapping is pinned in [High-level API](#over-acp); package-wise the bridge takes a type-only peer edge on `dsh-mode` and reads the service opportunistically, so a bridge without the plugin behaves exactly as today.
### The recorded scenario and the harness op
`input.json` gains one step op, `{ "op": "setMode", "modeId": "plan" }`, driven through the real `session/set_mode` RPC, and a scripted `elicitationAnswers` queue (FIFO, consumed by the harness client's elicitation callback — the review question's answer). The `plan-mode` scenario: initialize → newSession → setMode(plan) → a prompt the model answers by running a real `cat` through the bash tool INSIDE plan (executed under the clamped read-only sandbox on replay — Seatbelt on macOS, bwrap on Linux CI) and presenting the plan via `exit_plan_mode` → a scripted approve → the same turn's next step edits for real, unclamped. Because the mode is set before turn 1, the FIRST `request/header` snapshot is already in plan shape (the full toolset plus the exit tool, the mode section, reason `initial`); the approved exit logs the pure-removal `request/header-delta`, and the scenario pins both, plus the `mode/set` pair. A sibling `plan-mode-reject` scenario scripts the keep-planning answer with feedback text and pins the corrective result. Both need a with-key recording session; the guard's deny texts — and the sandbox-denial marker, whose recorded stderr would be the backend's dialect and replay only where it was recorded — are pinned at the unit tier.
`input.json` gains one step op, `{ "op": "setMode", "modeId": "plan" }`, driven through the real `session/set_mode` RPC, and a scripted `elicitationAnswers` queue (FIFO, consumed by the harness client's elicitation callback — the review question's answer). The `plan-mode` scenario: initialize → newSession → setMode(plan) → a prompt the model answers by running a real `cat` through the bash tool INSIDE plan (the composition's sandbox applies exactly as in default mode; on replay the command re-executes under the host runner — Seatbelt on macOS, bwrap on Linux CI) and presenting the plan via `exit_plan_mode` → a scripted approve → the same turn's next step edits for real. Because the mode is set before turn 1, the FIRST `request/header` snapshot is already in plan shape (the full toolset plus the exit tool, the mode section, reason `initial`); the approved exit logs the pure-removal `request/header-delta`, and the scenario pins both, plus the `mode/set` pair. A sibling `plan-mode-reject` scenario scripts the keep-planning answer with feedback text and pins the corrective result. Both need a with-key recording session; the sandbox-denial marker, whose recorded stderr would be the backend's dialect and replay only where it was recorded, stays pinned at `dsh-tool-bash`'s unit tier.
### The mechanical tail
No new cordis event is declared IN `dsh-mode` (`mode/set` rides `session/event`; the policy listeners attach to existing waterfalls) — the one new event, the `bash/resolve-mode` waterfall the access cap clamps, lives in `dsh-bash` where the resolution it wraps lives. Regenerated in the same change: the events catalog (`bash/resolve-mode`), the persistence log catalog (`mode/set`), the services catalog (`ctx.modes`, JSDoc-complete), the config catalog (`ModeConfig`), the tool catalog (`exit_plan_mode`), the producer/consumer map and doc graphs, and the module graph. Repo plumbing: a root tsconfig `paths` entry, the new group's README plus a [packages map](../../../../packages/README.md) row (a new top-level group is the deliberate act that table names), an `architecture.md` capability-services row for `ctx.modes` (budget-checked), and the cookbook row upgrade.
No new cordis event is declared (`mode/set` rides `session/event`; the listeners attach to existing waterfalls), so the events catalog is untouched. Regenerated in the same change: the persistence log catalog (`mode/set`), the services catalog (`ctx.modes`, JSDoc-complete), the config catalog (`ModeConfig`), the tool catalog (`exit_plan_mode`), the producer/consumer map and doc graphs, and the module graph. Repo plumbing: a root tsconfig `paths` entry, the new group's README plus a [packages map](../../../../packages/README.md) row (a new top-level group is the deliberate act that table names), an `architecture.md` capability-services row for `ctx.modes` (budget-checked), and the cookbook row upgrade.
## Deferred
Each behind its own decision: subagent mode inheritance via a forwarded `AgentOptions.mode` (the option field itself ships), preset modes beyond `plan` (read-only, accept-edits), the idle-record primitive if pending-intent loss proves real, and — the big one — **effects self-declaration on tool definitions**: a per-tool read-only/mutating classification (the MCP `ToolAnnotations` vocabulary — `readOnlyHint`/`destructiveHint` — is the natural template, with its untrusted-hint caveat implying trust tiers). That item is what a general per-mode tool policy waits on: this RFC first shipped an interim per-mode name allowlist and removed it before release — a hand-maintained list mislabels the effects question, must track every tool a deployment composes, and rots silently as tools arrive — so mode-scoped tool availability (and per-tool `ask` policies) returns as a CONSUMER of declared effects, which is its restart trigger.
The recorded snapshot scenarios are landed: `plan-mode` (the pinned-header arc — plan-shaped initial header, a real `cat`under the clamp, scripted elicitation approve, the pure-removal header-delta, a real edit) and `plan-mode-reject` (keep-planning feedback carried verbatim in the corrective `isError`), beside the keyless `modes-advertise` wire golden. The cap guard's deny paths stay pinned at the unit tier.
The recorded snapshot scenarios are landed: `plan-mode` (the pinned-header arc — plan-shaped initial header, a real `cat`inside plan, scripted elicitation approve, the pure-removal header-delta, a real edit) and `plan-mode-reject` (keep-planning feedback carried verbatim in the corrective `isError`), beside the keyless `modes-advertise` wire golden.
## FAQ
@@ -157,11 +130,11 @@ Behavioral clarifications of the chosen design; rejected designs live in [Altern
**What if a deployment composes no user-interaction provider?** Plan mode stays safe but manual: `ctx.userInteraction.ask()` throws `NO_PROVIDER` (and an absent seam never resolves at all), the tool returns the corrective `isError`, and the exit degrades to the user toggling modes — never to an unreviewed exit. The mode section tells the model to present its plan through `exit_plan_mode` — and to ask the user in prose if that fails — so it keeps presenting instead of stalling.
**Why is there no per-mode tool allowlist?** Because "which tools are safe in a read-only mode" is a property of each TOOL (its effects), not of the mode — a per-mode name list re-declares that fact in the wrong home, must enumerate every tool the deployment composes (MCP servers included), and rots silently as tools arrive. Plan mode therefore enforces exactly where an enforcer exists — the sandbox cap on the shell — and restrains everything else by its section until tool definitions declare their effects ([Deferred](#deferred), where the removed interim allowlist is archived with its restart trigger); the interim exposure is an accepted cost ([Consequences](#consequences)).
**Why is there no per-mode tool allowlist?** Because "which tools are safe in a planning mode" is a property of each TOOL (its effects), not of the mode — a per-mode name list re-declares that fact in the wrong home, must enumerate every tool the deployment composes (MCP servers included), and rots silently as tools arrive. Until tool definitions declare their effects ([Deferred](#deferred), where the removed interim allowlist is archived with its restart trigger), a mode restrains by its section and the exit review; the exposure is an accepted cost ([Consequences](#consequences)).
**Do subagents inherit the parent's mode?** A fork child inherits for free — the parent's `mode/set` is inside the seeded prefix. A spawn child starts in the default mode unless its creator seeds `AgentOptions.mode`; automatic forwarding by subagent providers is deferred ([Deferred](#deferred)).
**How does plan mode's read-only relate to the sandbox knob's read-only?** They are two independent folds over the same log with different owners: the knob (`bash/sandbox-mode`, [the sandbox RFC](2026-07-06-sandbox.md)) is the session's standing choice, the mode's `access` is a cap that rides the mode — and the cap is a clamp, never a write. `resolveMode` folds `override ?? default` and the clamp takes the ladder minimum at read time, per call, so the two switch in any order without interference: a knob flipped during plan stays logged but capped, exiting plan uncovers it unchanged, and there is no restore step for a crash to strand. The log attributes each axis to its own event — a clamped call's width to the standing`mode/set`, a knob change to its`bash/sandbox-mode` event.
**How does plan mode relate to the sandbox's read-only mode?** They are separate axes that never touch: the mode is the collaboration stance (a `mode/set` fold), the sandbox mode is an enforcement knob (a `bash/sandbox-mode` fold, [the sandbox RFC](2026-07-06-sandbox.md)) — plan mode neither reads nor caps it, exactly as Codex keeps its Plan/Default presets separate from its sandbox and approval settings. A user who wants kernel-enforced read-only while planning sets both: flip the mode picker AND the sandbox-mode option, in either order; each switch changes only its own fold, so there is no interference and no restore step to crash out of. The log attributes each axis to its own event — the stance to`mode/set`, the confinement to`bash/sandbox-mode`.
**Why aren't sandbox mode, approval policy, or the model themselves modes?** They are individual environment knobs and belong to ACP's `session/set_config_option`; the division this proposal pins is picker-to-modes / knobs-to-config-options, recorded in [the feature matrix](../../../../packages/ui/acp/acp-feature-support.md) now that both this stack's picker and the sandbox stack's config options are landed. A mode definition may later bundle env facts (applied through `ctx.envState` where mounted) so a Codex-style preset stays a single mode; fusing approval policy into the mode CONCEPT itself is rejected in [Alternatives considered](#alternatives-considered).
@@ -171,7 +144,7 @@ A survey of shipped plan modes (Claude Code, Cursor, Copilot, OpenCode, Gemini C
The mode surface is a LIST everywhere it is advertised, never a boolean: Claude Code's picker offers `plan` beside `acceptEdits` (plus an auto-mode entry into plan), and Codex exposes `Plan` beside `Default` as collaboration-mode presets while keeping approval and sandbox settings separate. This is the surface [the ACP feature matrix](../../../../packages/ui/acp/acp-feature-support.md) records as the gap, and what sizes the vocabulary as named modes rather than a flag.
The ecosystems that leave modes to convention show the failure shapes to avoid. Pi-style mode extensions fight over a last-wins global active-tool list, enforce "read-only" by prompt text alone (a hallucinated call to a still-registered tool executes), and re-inject plan state into every request to survive compaction. The contested global list and the re-injection hack close structurally here — per-agent folded state, and a log-only non-surface event compaction cannot shadow. The prompt-only hole closes where an enforcer exists: the shell is confined by the kernel-backed sandbox clamp, not by text; outside the shell the harness currently accepts guidance-only restraint, deliberately and temporarily ([FAQ](#faq)), rather than shipping the name-list non-fix.
The ecosystems that leave modes to convention show the failure shapes to avoid. Pi-style mode extensions fight over a last-wins global active-tool list, enforce "read-only" by prompt text alone (a hallucinated call to a still-registered tool executes), and re-inject plan state into every request to survive compaction. The contested global list and the re-injection hack close structurally here — per-agent folded state, and a log-only non-surface event compaction cannot shadow. The prompt-only shape, by contrast, is deliberately KEPT — it is what Codex ships for Plan, and it is why the mode axis composes freely with the enforcement axes: a deployment that wants a hard floor pairs the mode with the independent sandbox knob instead of the mode carrying its own enforcement ([FAQ](#faq)).
## Alternatives considered
@@ -181,9 +154,9 @@ The ecosystems that leave modes to convention show the failure shapes to avoid.
**Loop-owned mode state.** Rejected on the standing rule (plugins, not loop changes): every hook the feature needs — assemble, pre-execute, turn boundaries, session events — is already a documented seam, so a loop edit would buy nothing but coupling.
**A per-mode tool allowlist with a deny-by-default gate (the first shipped shape).** Removed before release. A hand-maintained name list re-declares a per-TOOL fact (its effects) per MODE: it must enumerate every tool the deployment composes — MCP servers and future registrations included — and it rots silently as tools arrive (a new read-only tool is blocked until someone edits every mode; the author burden lands on whoever knows the mode, not whoever knows the tool). It also over-promises: the list looks like a security boundary while the real boundary for anything non-shell does not exist yet. The replacement scopes enforcement to the one real enforcer (the sandbox `access` cap) and parks the general dimension on effects self-declaration ([Deferred](#deferred)). The interim consequence — outside the shell, plan mode is guidance-only, the very Pi hole the gate once closed — is accepted deliberately as a pre-release trade, priced in [Consequences](#consequences).
**A per-mode tool allowlist with a deny-by-default gate (the first shipped shape).** Removed before release. A hand-maintained name list re-declares a per-TOOL fact (its effects) per MODE: it must enumerate every tool the deployment composes — MCP servers and future registrations included — and it rots silently as tools arrive (a new read-only tool is blocked until someone edits every mode; the author burden lands on whoever knows the mode, not whoever knows the tool). It also over-promises: the list looks like a security boundary while the real boundary for anything non-shell does not exist. The general dimension is parked on effects self-declaration ([Deferred](#deferred)); the consequence — plan mode is guidance-only, the very Pi hole the gate once closed — is accepted deliberately, priced in [Consequences](#consequences).
**Prompt-only bash confinement.** The Pi failure shape ([Prior art](#prior-art)) applied to the one surface that matters most: asking nicely does not stop a shell command. The `access` cap is kernel-backed enforcement (`bash/resolve-mode` clamp over the sandbox executor), never text.
**An `access` sandbox cap on the mode (the second shipped shape).** Also removed before release. `ModeDefinition.access` clamped the bash seam's per-call sandbox resolution to a mode-declared ceiling (a `bash/resolve-mode` waterfall + ladder-min listener, with guards withholding bash under an unconfinable executor and denying escalation mid-mode). The state stayed orthogonal — the clamp never wrote the sandbox knob — but the AXES did not: entering plan changed what the sandbox enforced, fusing the collaboration stance with an enforcement level and contradicting the Codex-shaped separation the review converged on (Plan/Default presets never touch sandbox or approval settings). One user-visible symptom of the fusion: flipping the sandbox option to `workspace-write` while planning silently did nothing. The cap, the waterfall, and the mode→bash dependency edge were removed together; a deployment gets kernel-enforced read-only planning by pairing the mode with the independent sandbox-mode option, and a mode-triggered PRESET (a mode definition bundling suggested knob values, applied as ordinary knob switches) can return later without re-fusing the axes.
**Runtime-only mode (UI- or bridge-local, unlogged).** Resume and fork would silently drop the mode, and the header deltas a mode causes would have no attributable cause in the log. Logged state is what makes the mode auditable and restorable for free.
@@ -193,7 +166,7 @@ The ecosystems that leave modes to convention show the failure shapes to avoid.
**A boolean `planMode` instead of named modes.** Too narrow for the surface the repo already tracks: ACP advertises a mode LIST and the shipped pickers fill it with more than plan ([Prior art](#prior-art)); generalizing later would rename durable event vocabulary. The string-shaped mechanism costs nothing extra now; only `plan` ships as a definition.
**A tool-policy-stack service (the Pi-critique remedy).** A dedicated composition service for tool policies is premature: waterfall listeners compose by construction, and the narrow surface this plugin filters (the exit tool, an unhonorable-cap trio) makes filter-order races non-exploitable. Formalize only if real conflicts appear.
**A tool-policy-stack service (the Pi-critique remedy).** A dedicated composition service for tool policies is premature: waterfall listeners compose by construction, and the narrow surface this plugin filters (exactly the exit tool) makes filter-order races non-exploitable. Formalize only if real conflicts appear.
**Exit approval through the approval seam (a `{ kind: 'ask' }` gate decision).** The original sketch, natural while the approval seam was the only asking machinery in flight — but it seats a review in a permission chair: the seam's outcome vocabulary is deliberately closed and one-shot (`allowed-once`/`rejected`), so a rejection carries no feedback and an approval can never grow options (approve-and-accept-edits). The exit moment is a question, not a permission — the user-interaction seam gives it options plus the free-text channel, and the rejection feedback reaches the model verbatim. The approval seam remains the right seat for genuine permission gates (the sandbox escalation), and the registry's `ask` vocabulary stays available to deployments that want one there.
@@ -207,9 +180,9 @@ What holds now, pinned by the unit, protocol, and snapshot tiers:
- A user-driven flip narrates exactly once at the next boundary and a net-zero flip sequence narrates nothing; a tool-driven exit narrates only through its tool result.
- In the default mode the plugin is invisible: assemblies are byte-identical with and without `dsh-mode` loaded, and every pre-existing snapshot golden is unchanged.
- In plan mode the guidance section and the `exit_plan_mode` tool reach both the wire request and the logged header; entering plan logs the fallback header snapshot (front-of-list insertion), the approved exit logs the pure-removal header-delta.
-Under a confining executor the bash trio stays available in plan mode with every call's sandbox resolution clamped to `read-only` (the `bash/resolve-mode` waterfall); the session's sandbox knob is never written by the mode and re-emerges intact on exit; a `sandbox_permissions` escalation inside a capped mode is denied at the guard. Without a confining executor the trio is hidden and denied.
- Mode definitions (section text, `access` cap) are changeable from `cordis.yml` with no code edit; an unknown mode name fails validation loudly at `set()` time, an unknown definition key at load.
-`exit_plan_mode`'s approve path flips the mode and lifts the plan constraints on the next step; the keep-planning path returns the corrective `isError` carrying the user's feedback and stays in plan mode; the ACP `session/set_mode` round-trip updates `current_mode_update`, and the exit review prompts through each surface's user-interaction provider.
-Plan mode changes nothing on the enforcement axes: the toolset, the sandbox mode, escalation, and the approval policy behave identically in plan and default — pairing the mode with the independent sandbox/approval knobs is how a deployment hardens planning.
- Mode definitions (section text) are changeable from `cordis.yml` with no code edit; an unknown mode name fails validation loudly at `set()` time, an unknown definition key at load.
-`exit_plan_mode`'s approve path flips the mode and drops the plan surface on the next step; the keep-planning path returns the corrective `isError` carrying the user's feedback and stays in plan mode; the ACP `session/set_mode` round-trip updates `current_mode_update`, and the exit review prompts through each surface's user-interaction provider.
- The docs tail shipped with the landing: READMEs, regenerated catalogs (persistence log, config, cordis services, tools), the packages map and architecture rows, and the cookbook row.
The accepted costs: a pending user flip set while idle is lost if the process dies before the next turn (the UI re-applies; the idle-record primitive is the escape hatch if this bites in practice). Every mode transition is a logged header change and therefore a prefix-cache reset at the provider — inherent, visible in per-step usage, and an argument against mode-flapping UIs, not against the design. **Outside the shell, a non-default mode restrains mutations by guidance alone** until effects self-declaration lands: a model that ignores the section CAN write during plan — the review moment, the session log (every call attributable under the plan-shaped header), and the fs stack's own policies are the audit surface meanwhile; this is the deliberate pre-release trade archived in [Alternatives considered](#alternatives-considered), with the effects item in [Deferred](#deferred) as its restart trigger. The mode filter prepends and hides only the exit tool and an unhonorable-cap bash trio; a listener that ALSO prepends after `dsh-mode` loads could re-show them — the cap guard keeps an unconfined bash non-executable either way, and a re-shown exit tool self-rejects outside plan, so the residual is cosmetic. Plan mode's shell power is exactly as real as the composition: under `dsh-bash-local` (or no executor) the trio is withheld in plan — an unhonorable cap must not be offered — and the guard names the three bash tools rather than deriving them from tool metadata, the same generalization gap the effects item closes. The ACP mode surface carries both this stack's picker and the sandbox stack's config options under the picker-to-modes / knobs-to-config-options division pinned in the [FAQ](#faq), recorded in [the feature matrix](../../../../packages/ui/acp/acp-feature-support.md). The ACP spec's draft v2 direction reportedly slates session modes for removal in favor of config options; if that lands, the picker migrates to a config-option select mechanically — the mode state and every policy surface are wire-agnostic — accepted.
The accepted costs: a pending user flip set while idle is lost if the process dies before the next turn (the UI re-applies; the idle-record primitive is the escape hatch if this bites in practice). Every mode transition is a logged header change and therefore a prefix-cache reset at the provider — inherent, visible in per-step usage, and an argument against mode-flapping UIs, not against the design. **A mode restrains by guidance alone**: a model that ignores the section CAN mutate during plan — the review moment, the session log (every call attributable under the plan-shaped header), and the independent enforcement axes (the sandbox mode, the approval policy, the fs stack's own policies) are the containment surface, and hardening planning means setting those knobs, not widening the mode; the two removed enforcement shapes and their restart trigger (effects self-declaration) are archived in [Alternatives considered](#alternatives-considered) and [Deferred](#deferred). The mode filter prepends and hides only the exit tool; a listener that ALSO prepends after `dsh-mode` loads could re-show it — a re-shown exit tool self-rejects outside plan, so the residual is cosmetic. The ACP mode surface carries both this stack's picker and the sandbox stack's config options under the picker-to-modes / knobs-to-config-options division pinned in the [FAQ](#faq), recorded in [the feature matrix](../../../../packages/ui/acp/acp-feature-support.md). The ACP spec's draft v2 direction reportedly slates session modes for removal in favor of config options; if that lands, the picker migrates to a config-option select mechanically — the mode state and every policy surface are wire-agnostic — accepted.
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