Merge origin/master into lsp

docs/core-data-structures/core.md

@@ -16,15 +16,16 @@ Everything else is documented on a **sub-page**, not here. The rule that draws t
 | Sub-page | Owns |
 |---|---|
 | [llm-streaming.md](llm-streaming.md) | the `StreamChunk` wire protocol + adapter contract, `BlockAssembler`, the `LlmAdapter` seam |
+| [token-meter.md](token-meter.md) | immutable scalar and positional replay measurements with consumed-log revisions |
 | [scope.md](scope.md) | scoped registration identity, dispatch carriers, and the owned `Scope` context |
 | [session.md](session.md) | the full `SessionEventMap` variant catalog, `TurnTrigger`/`TurnEndReason`, `deriveMessages()`, the turn-enclosure invariant |
 | [persistence.md](persistence.md) | the durability seam: `SessionPersistence`, JSONL + SQLite backends, `session/flush`, crash recovery, `SessionHeader` |
-| [session-query.md](session-query.md) | logical session/event records and bounded exact-event reads |
+| [session-query.md](session-query.md) | logical records, bounded exact-event reads, and relationship traces |
 | [system-prompt.md](system-prompt.md) | per-assembly context, tool-provider results, prompt sections, and cooperative assembly |
 | [tools.md](tools.md) | `ToolDefinition` full fields, the schema DSL, `ToolExecution`/`ToolResult`, tool-presentation UI types, and the guarded execution pipeline |
 | [user-interaction.md](user-interaction.md) | the UI-backed human question/answer seam: `AskUserQuestionRequest`, answer/options vocabulary, provider API, error taxonomy |
 | [approval.md](approval.md) | the one-shot user-approval seam: `ApprovalRequest`, `ApprovalOutcome`, per-session policy, audit and answerer contracts |
-| [bash.md](bash.md) | the bash executor seam: `BashExecRequest`/`Spec`, `BashRunResult`, background `BashTask`s |
+| [bash.md](bash.md) | the bash executor seam: `BashExecRequest`/`Spec`, `BashRunResult`, background `BashProcess` handles |
 | [sandbox.md](sandbox.md) | the process-confinement seam: file-effect modes, `SandboxPolicy`, `ConfinedArgv`, enforcement and fail-closed errors |
 | [code-runtime.md](code-runtime.md) | the code-execution seam: `CodeRunRequest`/`Result`, binding namespaces, captured logs, the `CodeRunFailure` taxonomy |
 | [filesystem.md](filesystem.md) | the filesystem seam: `FsTarget`, read/write/edit outcomes, observed-file state, `FsErrorCode` |
@@ -33,11 +34,10 @@ Everything else is documented on a **sub-page**, not here. The rule that draws t
 | [compaction.md](compaction.md) | the compaction seam: the `compact/*` session events, `CompactionResult`, the `CompactService` interface |
 | [subagent.md](subagent.md) | the subagent seam: the named-provider registry, `SubagentStartRequest`/`Result`/`Run`, the start-time-vs-runtime capability split |
 | [web.md](web.md) | the web access seam: `WebSearchRequest`/`Result`, `WebFetchRequest`/`Result`, `WebFetchBody`, provider availability, `WebError` |
+| [spill.md](spill.md) | the spill storage seam: `SaveTextSpill`, `SpillOwner`/`SpillSource`, `SpillRef`, the branded `SpillLocator` |
 | [workflow.md](workflow.md) | the workflow seam: `WorkflowStartRequest`, `WorkflowMeta`, `WorkflowRun`/`Result`, the `workflow/*` event payloads, `WorkflowError` fatality |
 
-> Type definitions on this page are pasted **verbatim** from source and drift-checked by `pnpm run verify-type-equiv` (see [development.md](../development.md#documenting-types-verbatim-ts-type-equiv)). Inline JSDoc is omitted for readability; follow the source link for the full contracts.
-
-FIXME(catalog-verbs): the drift gate covers only the nouns (the pasted type shapes); every method surface on these pages is hand-written prose. core-data-structures should probably also generate the *verbs* — the public methods of the cataloged classes — so a signature change cannot silently outdate the catalog.
+> Type declarations and their JSDoc on these pages are source-equivalent and drift-checked by `pnpm run verify-type-equiv` (see [development.md](../development.md#documenting-types-verbatim-ts-type-equiv)). Ordinary blocks preserve complete declarations; `public-api` blocks preserve body-stripped public class declarations. Cordis services use the generated [service catalog](../cordis-catalog/services.md).
 
 ## The `…Map → derived-union` pattern
 
@@ -75,17 +75,18 @@ Two large discriminated unions are the ones consumers `switch` over most: **`Str
 
 ## Branded IDs
 
-IDs that cross package boundaries are **branded** — structurally strings, but non-interchangeable at the type level (an `AgentId` can't be passed where a `CallId` is expected). Construction goes through a per-type factory; comparison, logging, and JSON behave as ordinary strings.
+IDs that cross package boundaries are **branded** — structurally strings, but non-interchangeable at the type level (a `SessionId` cannot be passed where a `CallId` is expected). Construction goes through a per-type factory; comparison, logging, and JSON behave as ordinary strings.
 
-The `Branded<B>` primitive lives in its own type-only package, [dsh-brand](../../packages/util/brand) (no runtime code, no harness-package dependency), so any package can brand the ids it owns without depending on an unrelated capability package (e.g. dsh-bash brands `BashTaskId`/`OwnerToken` via dsh-brand alone, never pulling in dsh-llm).
+The `Branded<B>` primitive lives in its own type-only package, [dsh-brand](../../packages/util/brand) (no runtime code, no harness-package dependency), so any package can brand the ids it owns without depending on an unrelated capability package.
 
 Source: [`packages/util/brand/src/index.ts`](../../packages/util/brand/src/index.ts)
 
 ```ts type-equiv
+/** A string carrying a compile-time-only brand `B`. */
 type Branded<B extends string> = string & { readonly [BRAND]: B }
 ```
 
-The three core IDs: `CallId` (correlates a tool call with its result; dsh-llm), `SessionId` (dsh-session), `AgentId` (dsh-agent). Each is `Branded<'CallId'>` etc. plus a same-named factory function. Capability seams brand their own ids too — see `BashTaskId`/`OwnerToken` in [bash.md](bash.md).
+The two core IDs are `CallId` (correlates a tool call with its result; dsh-llm) and `SessionId` (the shared live agent and durable session identity; dsh-session). Capability packages brand their own ids too, such as `TaskId` in [tasks.md](tasks.md).
 
 ## Content blocks and messages
 
@@ -94,6 +95,10 @@ A conversation is `Message`s; a message is an array of typed **content blocks**.
 Source: [`packages/llm/llm/src/types.ts`](../../packages/llm/llm/src/types.ts)
 
 ```ts type-equiv
+/**
+ * Merge-extensible content blocks keyed by `type`. New core blocks must land
+ * with adapter, UI, and compaction support.
+ */
 interface ContentBlockMap {
   'text': TextBlock
   'reasoning': ReasoningBlock
@@ -104,18 +109,44 @@ interface ContentBlockMap {
 
 The block interfaces (full fields in source): `TextBlock` (`text`), `ReasoningBlock` (thinking, distinct from visible text), `ToolCallBlock` (`id: CallId`, `name`, raw-JSON `arguments`), `ToolResultBlock` (`toolCallId`, nested `content: ContentBlock[]`, `isError?`). `ContentBlock = ContentBlockMap[ContentBlockType]`. The core set is limited to blocks every shipping path honors — multimodal content (images, audio, …) has no core block type; a feature that needs one adds it via the merge-extensible map together with the adapter/UI/compaction support that honors it.
 
-A `Message` is a role plus blocks:
+A `Message` is a role plus blocks. Loop-derived assistant messages carry their durable provider/model identity and optional adapter-private replay metadata:
 
 ```ts type-equiv
+/** Provider ownership and adapter-private replay data for an assistant message. */
+interface AssistantProvenance {
+  /** Provider route that produced the message. */
+  provider: string
+  /** Provider model id that produced the message. */
+  model: string
+  /**
+   * Lossless-JSON adapter state needed to replay the provider response.
+   * `LlmService` exposes it to a target adapter only when that adapter instance
+   * currently owns both this historical provider and the target provider.
+   */
+  replayState?: unknown
+}
+```
+
+```ts type-equiv
+/**
+ * A single message in a conversation history. Loop-derived assistant messages
+ * always carry provenance; callers may omit it on hand-built foreign history.
+ */
 interface Message {
   role: 'system' | 'user' | 'assistant'
   content: ContentBlock[]
+  /** Present only on assistant messages produced by a routed adapter. */
+  provenance?: AssistantProvenance
 }
 ```
 
 Where a message came from is itself a merge-extensible sum type:
 
 ```ts type-equiv
+/**
+ * Where a message (or injected content) came from.
+ * Merge-extensible sum type — plugins add their own `kind`s.
+ */
 interface MessageSourceMap {
   user: { kind: 'user' }
   plugin: { kind: 'plugin'; plugin: string }
@@ -134,8 +165,37 @@ One model call is a fully-assembled `GenerateOptions`. The adapter answers with
 
 Source: [`packages/llm/llm/src/types.ts`](../../packages/llm/llm/src/types.ts)
 
+Provider and model discovery uses small provider-neutral descriptors. A model catalog is advisory: routing still keys on a registered provider, and an adapter may accept unlisted model ids.
+
 ```ts type-equiv
+/** Display metadata for one registered provider route. */
+interface LlmProviderInfo {
+  /** Provider route key used by {@link GenerateOptions.provider}. */
+  id: string
+  /** Human-readable provider name for selectors and diagnostics. */
+  name: string
+}
+```
+
+```ts type-equiv
+/** One adapter-discovered model; catalog membership is advisory, not request validation. */
+interface LlmModelInfo {
+  /** Provider route that owns this model entry. */
+  provider: string
+  /** Model id passed to {@link GenerateOptions.model}. */
+  id: string
+  /** Human-readable model name for selectors. */
+  name: string
+  /** Optional user-facing distinction from otherwise similar models. */
+  description?: string
+}
+```
+
+```ts type-equiv
+/** A single model request, fully assembled. */
 interface GenerateOptions {
+  /** Registered provider route selecting the adapter instance. */
+  provider: string
   model: string
   /**
    * Ordered conversation messages, exactly as the provider sees them (after
@@ -168,6 +228,10 @@ interface GenerateOptions {
 Why a model response stopped is a merge-extensible reason:
 
 ```ts type-equiv
+/**
+ * Why a model response stopped.
+ * Merge-extensible so adapters can surface provider-specific reasons.
+ */
 interface FinishReasonMap {
   'stop': { kind: 'stop' }
   'tool-calls': { kind: 'tool-calls' }
@@ -182,6 +246,13 @@ interface FinishReasonMap {
 `GenerateOptions.tools` carries `ToolSchema` — the JSON-schema description of a tool, as sent to the model. It is declared in dsh-llm (not dsh-tools) precisely because it is part of the request the loop assembles every step:
 
 ```ts type-equiv
+/**
+ * JSON-schema description of a tool, as sent to the model.
+ *
+ * Declared here (not in dsh-tools) because it is part of {@link GenerateOptions};
+ * dsh-tools' ToolDefinition and dsh-system-prompt's PromptAssembly both import
+ * it from this package.
+ */
 interface ToolSchema {
   name: string
   description: string
@@ -194,16 +265,22 @@ The model-facing `ToolSchema` is the wire shape; the registered `ToolDefinition`
 
 ### The request envelope: `LlmCallConfig` and the logged header
 
-The loop builds each request from logged state. `EpochHeader` records call config, rendered prompt, authoritative returned tool order (configured by `toolOrder`, or lexicographic when unset), and session prefix through `request/header` snapshots and deltas. Together with derived history, this makes the request reconstructable from the session log. See [session.md](session.md#the-request-header-events-requestheader-and-requestheader-delta) and the [reconstructability RFC](../rfc/implemented/architecture/2026-07-05-reconstructable-requests.md).
+The loop builds each request from logged state. `EpochHeader` records call config, rendered prompt, authoritative returned tool order (configured by `toolOrder`, or lexicographic when unset), and session prefix through full `request/header` snapshots. Together with derived history, this makes the request reconstructable from the session log. See [session.md](session.md#the-request-header-event-requestheader) and the [reconstructability Agent Note](../../.agents/notes/implemented/architecture/2026-07-05-reconstructable-requests.md).
 
-`agent/request` receives a frozen call-config seed and may return a replacement. `agent/session-prefix` composes request-only prefix messages once per loop instance, and the header records the exact result used. Requests reaching `llm/stream` are deep-frozen, so mutation throws.
+`agent/request` receives a frozen call-config seed and may return a replacement to switch provider, model, or sampling. `agent/session-prefix` composes request-only prefix messages once per loop instance, and the header records the exact result used. Requests reaching `llm/stream` are deep-frozen, so mutation throws.
 
 On the wire, a loop-built request reads in this order: the `system` slot (the rendered prompt assembly) → `messagePrefix` (the frozen session prefix) → the derived history — the boundary snapshot, whose tail is the newest `user/message` on a turn's first step and the previous step's tool results on later steps. The prefix never enters the derived history; its durable record is the header events, and the dev invariant recomputes exactly this equation against every loop-built request.
 
 FIXME(call-config-shape): revisit the exact definition of this type — which fields are genuinely epoch-level for cache purposes (`model` certainly; the sampling scalars sit here out of caution), and where provider-specific extras (reasoning options, extra body params) belong when an adapter needs them.
 
 ```ts type-equiv
+/**
+ * Provider + model + sampling scalars of one conversation's requests. Every field maps
+ * 1:1 onto the same-named `GenerateOptions` field; the loop builds requests
+ * from the logged header rather than accepting these per call.
+ */
 interface LlmCallConfig {
+  provider: string
   model: string
   temperature?: number
   maxTokens?: number
@@ -218,6 +295,19 @@ A `Session` is an **append-only log** of typed `SessionEvent`s — the single so
 Source: [`packages/core/session/src/types.ts`](../../packages/core/session/src/types.ts)
 
 ```ts type-equiv
+/**
+ * One immutable entry in the session log.
+ *
+ * A proper discriminated union over `type` (not independent `type`/`data`
+ * unions), so `switch (event.type)` narrows `event.data` without casts.
+ *
+ * The {@link sourceEventSeqs} and {@link surfaceOp} fields are conditional:
+ * they only exist on {@link SurfaceEventType} variants (`user/message`,
+ * `assistant/message`, `tool/result`, `context/message`, `steering/message`).
+ * Non-surface events (boundary markers, chunks, usage, errors) never carry
+ * surface metadata — the compiler enforces this at `Session.append()`
+ * call sites.
+ */
 type SessionEvent<T extends SessionEventType = SessionEventType> = {
   [K in SessionEventType]: {
     type: K
@@ -230,7 +320,9 @@ type SessionEvent<T extends SessionEventType = SessionEventType> = {
     /**
      * Seq numbers of events that are provenance sources of this event
      * (e.g. the `assistant/chunk` seqs that built an `assistant/message`,
-     * or the surface nodes shadowed by a compaction replace node).
+     * or the surface nodes shadowed by a compaction replace node). An
+     * `assistant/message` may carry a present empty array for a known empty
+     * provider stream; omission means unrecorded provenance.
      */
     sourceEventSeqs?: number[]
     /** How this event entered the surface; absent for non-surface events. */
@@ -239,37 +331,40 @@ type SessionEvent<T extends SessionEventType = SessionEventType> = {
 }[T]
 ```
 
-The fifteen event variants (`turn/start`, `turn/end`, `step/start`, `step/end`, `user/message`, `prompt/blocked`, `context/message`, `assistant/chunk`, `assistant/message`, `tool/call`, `tool/result`, `steering/message`, `todo/write`, `request/header`, `request/header-delta`), the `deriveMessages()` projection rules, the `TurnTrigger`/`TurnEndReason` reasons, and the turn-enclosure invariant are on **[session.md](session.md)**. How the log is made durable — the `SessionPersistence` seam, JSONL/SQLite backends, the `session/flush` checkpoint, crash recovery, and `SessionHeader` — is on **[persistence.md](persistence.md)**.
+The fourteen event variants (`turn/start`, `turn/end`, `step/start`, `step/end`, `user/message`, `prompt/blocked`, `context/message`, `assistant/chunk`, `assistant/message`, `tool/call`, `tool/result`, `steering/message`, `todo/write`, `request/header`), the `deriveMessages()` projection rules, the `TurnTrigger`/`TurnEndReason` reasons, and the turn-enclosure invariant are on **[session.md](session.md)**. How the log is made durable — the `SessionPersistence` seam, JSONL/SQLite backends, the `session/flush` checkpoint, crash recovery, and `SessionHeader` — is on **[persistence.md](persistence.md)**.
 
 ## The agent handle
 
-`Agent` is the surface every plugin (UI, hooks, orchestrators) programs against. The concrete implementation is `ReactLoopAgent` in dsh-agent-loop; nothing outside the loop depends on the implementation.
+`Agent` is the surface every plugin (UI, hooks, orchestrators) programs against. The concrete implementation is package-internal to dsh-agent-loop; nothing outside the loop depends on it.
 
 Source: [`packages/core/agent/src/types.ts`](../../packages/core/agent/src/types.ts)
 
+`InjectOptions` extends ordinary message attribution with context-only framing and durable model-hidden JSON metadata:
+
 ```ts type-equiv
+/** Options specific to durable synthetic context injection. */
+interface InjectOptions extends SendOptions {
+  /** Keep the canonical context tag, or send caller-owned framing verbatim. */
+  envelope?: ContextEnvelope
+  /** Opaque JSON state retained in the session event but hidden from the model. */
+  meta?: JsonValue
+}
+```
+
+```ts type-equiv
+/** Public agent handle; its concrete implementation is internal to `@deepseek-ai/dsh-agent-loop`. */
 interface Agent {
-  readonly id: AgentId
+  /** The single identity shared with {@link session}. */
+  readonly id: SessionId
   readonly options: AgentOptions
   readonly session: Session
   readonly status: AgentStatus
-
-  /**
-   * The agent's scope context (`@deepseek-ai/dsh-scope`, key = this agent):
-   * registrations through it — tools, prompt sections/variables, listeners,
-   * restrictions — are visible to this agent only and unwind when it is
-   * disposed; `agent.ctx.on('agent/…')` listeners fire only for this agent.
-   */
+  /** Agent-scoped context; its contributions are agent-local, unwind on disposal, and reject registration afterward. */
   readonly ctx: Context
 
   /**
-   * Queue a user message. Starts a turn when idle; otherwise waits for the next
-   * turn. Content and the resolved source are accepted as one detached,
-   * deeply-frozen lossless-JSON record before notification or enqueue, so
-   * caller or `agent/queued` listener in-place mutation cannot change later
-   * log/model input. Throws synchronously when either value is not losslessly
-   * JSON-serializable; `agent/prompt-submit` may still return an explicit
-   * replacement.
+   * Queue detached, frozen lossless-JSON input; starts a turn when idle.
+   * Invalid input throws synchronously before notification or enqueue.
    */
   send(content: ContentBlock[], options?: SendOptions): void
 
@@ -281,115 +376,107 @@ interface Agent {
   steer(content: ContentBlock[], options?: SendOptions): void
 
   /**
-   * Inject in-session context (file-change notices, skill content, cron
-   * notifications, …): appends a `context/message` session event the next model
-   * request sees at its chronological position, rendered as tagged synthetic
-   * context rather than a user prompt. Does not run the model.
-   *
-   * Turn-enclosure (the turn-enclosure RFC): an inject while a turn is open joins that turn;
-   * an inject while idle wraps its `context/message` in a one-shot `injection`
-   * turn (`turn/start` → `context/message` → `turn/end`) and checkpoints it for
-   * durability, so every event stays inside a turn and a persistence backend
-   * never loses a between-turn notice. The idle checkpoint is fire-and-forget
-   * (inject is synchronous): a failing flush is reported via `agent/error`
-   * (step `0`) and the logger, never thrown into the caller.
-   *
-   * Live-adapter review has validated the tagged-envelope rendering against
-   * current DeepSeek behavior; provider-specific mismatches belong in that
-   * adapter, not in the canonical session vocabulary.
+   * Append detached model-facing context without running the model. An open-turn
+   * injection joins at the current log position unless the current tool batch is
+   * executing; then it waits FIFO until that batch settles and drains before turn
+   * close even when interrupted. Idle injection uses a one-shot turn and durability
+   * checkpoint. Disposal awaits idle checkpoints; flush failures report through `agent/error`.
    */
-  inject(content: ContentBlock[], options?: SendOptions): void
+  inject(content: ContentBlock[], options?: InjectOptions): void
 
   /**
-   * Cancel ALL pending work for the agent. `cancel()`:
-   *
-   * - clears the queued FIFO (un-started prompts never run) and the steering
-   *   FIFO (steering for the cancelled turn is dropped, not re-enqueued);
-   * - aborts the in-flight step if one is running (the turn ends `aborted`);
-   * - drops a turn that is about to start (a `cancel()` landing in the
-   *   pre-step window — after a `send()` queued but before the loop flips to
-   *   `running`, or after `running` is emitted but before the first step) so
-   *   that queued prompt does not run and cannot be batched into the cancelled
-   *   turn.
-   *
-   * After `cancel()`, `whenIdle()` resolves on the post-cancel quiescent state.
-   * `cancel()` on an idle agent with nothing queued or running is a safe no-op
-   * — it does NOT arm anything that would drop a later legitimate prompt.
+   * Clear queued and steering work, including work waiting to start, and abort
+   * the active step. The supplied reason is preserved across pre-step and active
+   * cancellation windows, and `whenIdle()` resolves after cancellation reaches
+   * quiescence. Idle cancellation is a no-op and does not arm a later cancel.
    */
   cancel(reason?: string): void
 
-  /**
-   * Resolve once the agent has reached quiescence after settling out of
-   * `running`, or immediately if it is already idle with no queued work. A
-   * non-owner's quiescence-observation hook: a consumer that does NOT own the
-   * agent's lifecycle awaits this to proceed only after queued/running work has
-   * fully stopped, rather than returning while the driver is still streaming or
-   * about to start a queued turn — without itself tearing the agent down. (A
-   * lifecycle OWNER does not need it: `AgentHandle.dispose()` already awaits the
-   * loop-exit promise directly as part of stopping and unregistering. So this is
-   * for a non-owning observer — e.g. a test awaiting a turn to settle, or a
-   * monitor — that wants the settle signal but must not dispose the agent.)
-   *
-   * "Quiescence", not merely "status changed": a disposed agent emits
-   * `agent/status('disposed')` from inside its disposer, BEFORE the driver loop
-   * has unwound — so `whenIdle()` resolving on `disposed` must wait for the loop
-   * to actually exit (the implementation chains the loop-exit promise), not just
-   * observe the status flip. A mid-step disposal that never reaches `idle` still
-   * unblocks the await this way.
-   */
+  /** Resolve at idle quiescence; disposal waits for driver exit rather than only the status transition. */
   whenIdle(): Promise<void>
 
-  // Subagent delegation is realized on top of this interface by the
-  // `@deepseek-ai/dsh-subagent` seam, not by a method here: a backend creates
-  // the child through `ctx.agents.create` (fork seeds the child Session with a
-  // balanced prefix of the parent's log via `CreateAgentOptions.seed`; spawn
-  // starts fresh) and drives it as an ordinary Agent handle, so steer() and
-  // event subscription work uniformly. See docs/core-data-structures/subagent.md.
 }
 ```
 
-`AgentStatus` is `'idle' | 'running' | 'disposed'`, and `AgentId` is branded. `AgentOptions` is merge-extensible and currently includes `model?`. Persona belongs to `dsh-system-prompt`: an agent-scoped `deployment:persona` may shadow the global default.
+`AgentStatus` is `'idle' | 'running' | 'disposed'`, and `SessionId` is branded. `AgentOptions` is merge-extensible and currently includes `provider?` and `model?`; dispatch requires both after `agent/request`. Persona belongs to `dsh-system-prompt`: an agent-scoped `deployment:persona` may shadow the global default.
 
 The [event taxonomy](../architecture.md#event) owns the `agent/*` lifecycle, checkpoint, and waterfall contracts. Turn and step boundaries are durable session events rather than agent emits.
 
+## Initiating Agent
+
+The process-local initiator carried by `ctx.agents` is the exact `Agent` above, not a separate frame or copied identity. Ambient presence is neither liveness proof nor authorization; the [initiator-scope decision](../../.agents/notes/implemented/architecture/2026-07-15-agent-initiator-scope.md) owns its lifetime and boundary rules.
+
 ## Interception decisions
 
-Each `agent/*` interception waterfall returns a small, seam-specific typed union — the unified Decision idiom (the tool seams' `PreToolDecision`/`PostToolDecision` in [tools.md](tools.md) follow the same shape). A CC/Codex hook bridge maps its `permissionDecision`/`decision`/`continue`/`additionalContext` fields onto these; a native plugin returns them directly. They share one envelope for model-facing context, `HookContext`, which is `inject()`ed as a `context/message` and so carries a REQUIRED `source` (a missing source would default to `{kind:'user'}` and mislabel plugin context as a user prompt).
+Each `agent/*` interception waterfall returns a small, seam-specific typed union — the unified Decision idiom (the tool seams' `PreToolDecision`/`PostToolDecision` in [tools.md](tools.md) follow the same shape). A CC/Codex hook bridge maps its `permissionDecision`/`decision`/`continue`/`additionalContext` fields onto these; a native plugin returns them directly. Prompt and post-tool decisions share one model-facing context shape, `HookContext`, which is `inject()`ed as a `context/message` and therefore carries a REQUIRED `source` (a missing source would default to `{kind:'user'}` and mislabel plugin context as a user prompt). Its optional `envelope` selects the canonical context tag or caller-owned raw framing, while JSON `meta` persists plugin state without exposing it to the model. Both decisions carry `additionalContexts[]` so every entry preserves its own provenance, framing, and metadata. Continuation reasons are steering messages instead and deliberately use the narrower content/source shape.
 
 Source: [`packages/core/agent/src/types.ts`](../../packages/core/agent/src/types.ts)
 
 ```ts type-equiv
+/** Model-facing context injected by a listener; `source` prevents plugin text from being labeled as user input. */
 interface HookContext {
   content: ContentBlock[]
   source: MessageSource
+  /** Keep the canonical context tag, or use caller-owned framing verbatim. */
+  envelope?: ContextEnvelope
+  /** Opaque JSON state retained in the session event but hidden from the model. */
+  meta?: JsonValue
 }
 ```
 
-`agent/prompt-submit` returns a `PromptDecision` (allow a drained queued message — optionally rewriting its `content` or attaching `additionalContext` — or block it; a batch whose every prompt is blocked opens a zero-step turn that ends `rejected`):
+`agent/prompt-submit` returns a `PromptDecision` (allow a drained queued message — optionally rewriting its `content` or attaching `additionalContexts` — or block it; a batch whose every prompt is blocked opens a zero-step turn that ends `rejected`):
 
 ```ts type-equiv
+/**
+ * Prompt interception result. `allow.content` replaces the prompt and each
+ * `additionalContexts` entry becomes a separate context message. `block` records a
+ * durable `prompt/blocked`; an all-blocked batch ends a zero-step rejected turn.
+ */
 type PromptDecision =
-  | { kind: 'allow'; content?: ContentBlock[]; additionalContext?: HookContext }
+  | { kind: 'allow'; content?: ContentBlock[]; additionalContexts?: HookContext[] }
   | { kind: 'block'; reason: string }
 ```
 
-`agent/turn-continuation` returns a `ContinuationDecision` (the loop's default is `continue` when the step had tool calls or steering was injected, else `stop`; a `continue` `reason` is recorded as next-step steering in the same turn — the typed `/goal` pattern):
+`agent/turn-continuation` returns a `ContinuationDecision` (the loop's default is `continue` when the step had tool calls or steering was injected, else `stop`; a `continue` `reason` is recorded as next-step steering in the same turn and therefore carries no context envelope or metadata — the typed `/goal` pattern):
 
 ```ts type-equiv
+/** Turn continuation override; a continue reason is recorded as next-step steering in the same turn. */
 type ContinuationDecision =
   | { action: 'stop' }
-  | { action: 'continue'; reason?: HookContext }
+  | { action: 'continue'; reason?: { content: ContentBlock[]; source: MessageSource } }
 ```
 
+`agent/request-error` receives the original `RequestError`, whose optional provider-neutral `code` supports stable routing without message parsing:
+
+```ts type-equiv
+/** Model-request failure with an optional machine-routable provider code. */
+type RequestError = Error & { code?: string }
+```
+
+It returns a `RequestErrorDecision`; `retry` opens a new numbered step after the recovery listener's durable mutation, while `fail` preserves that error:
+
+```ts type-equiv
+/** Failed-request recovery decision; `retry` opens another numbered step while listeners delegate by calling `next()`. */
+type RequestErrorDecision = { action: 'fail' } | { action: 'retry' }
+```
+
+`agent/post-step` is awaited after assistant output, real or synthetic tool results, buffered context, and steering are durable but before `step/end`. A cancelled tool batch reaches it with an aborted signal after draining; its signature is `(agent, turn, step, signal)`, and replayable facts remain in the session log rather than a transient payload.
+
 `agent/turn-stop` returns the stop-only `ContinuationStop` subset or `undefined`. The loop calls this serial checkpoint after folding the ordinary decision, its reason, and pending steering; a stop is terminal and discards pending steering.
 
 ```ts type-equiv
+/**
+ * The terminal subset of {@link ContinuationDecision}. A listener on
+ * `agent/turn-stop` returns this to make the already-composed continuation
+ * outcome terminal; `undefined` abstains.
+ */
 type ContinuationStop = Extract<ContinuationDecision, { action: 'stop' }>
 ```
 
 `agent/session-start` carries a `SessionStartSource` (why the session lifecycle began; a bridge keys its SessionStart matcher on it):
 
 ```ts type-equiv
+/** Why a session lifecycle began; seeded creates are `startup`, while persisted loads are `resume`. */
 type SessionStartSource = 'startup' | 'resume' | 'clear' | 'compact'
 ```