feat(web): declare the remaining context forms on every shipped producer

Four values complete the vocabulary, so the opaque body is reached only by
producers that genuinely promise no shape.

`snapshot` — current state a later snapshot supersedes. system-prompt now
exposes `renderContextSections()`, the named contributions
`renderContextSnapshot()` already joins for the model, so the body attributes
each part to the subsystem that produced it instead of re-splitting joined
prose. The runtime snapshot, time-context, and tmux-context declare it.

`notice` — a one-off account of what just happened, declared by tool-tasks,
goal state changes, tool-goal wrap-up, plan-mode switches, and
repeat-tool-guard. Its `summary` rides the COLLAPSED row: these five are the
majority of shipped producers and none of them needs expanding to be read.
The task summary bounds itself because its inputs are unbounded caller text.

`relay` — a message another agent addressed to this one; both subagent
sources declare it and the body names the sender above what it said.

`recall` — material lifted from another session's log. session-reference
needed no new field: its references already record retained and omitted
counts and the truncation flag, which the body shows first, because recalled
context is bounded on the way in.

`ContextFormed` is now discriminated by `form`, so a producer cannot declare
a shape without the facts that shape is presented from — a notice without its
summary, or a snapshot without its sections, fails to compile.

Only the two hook bridges stay opaque, by design: their content is whatever
an external program printed, so no shape can be promised for it. Unknown
kinds and unreadable records land there too.

docs/core-data-structures/core.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write docs/core-data-structures/core.md
-core.md: 7761930b7f133600e89befd1bda96cfc7d2f05f5
-core.zh.md: 1a68b47229e3c961e772e7b0db33ded91b025e2e
+core.md: a3017060c318da6f5c8a02c0c0ddc5ffd1695fd6
+core.zh.md: ceefc0800b8f318472192880a3e383150a7fe5cc

docs/core-data-structures/core.md

@@ -191,6 +191,14 @@ type ContextForm =
   | 'instructions'
   /** A catalog of items available in this session, republished as it changes. */
   | 'catalog'
+  /** Current state, where a later snapshot from the same producer supersedes an earlier one. */
+  | 'snapshot'
+  /** A one-off account of something that just happened; it supersedes nothing. */
+  | 'notice'
+  /** A message another agent addressed to this one. */
+  | 'relay'
+  /** Material lifted out of another session's log, possibly reduced on the way in. */
+  | 'recall'
 ```
 
 ```ts type-equiv

docs/core-data-structures/core.zh.md

@@ -197,6 +197,14 @@ type ContextForm =
   | 'instructions'
   /** A catalog of items available in this session, republished as it changes. */
   | 'catalog'
+  /** Current state, where a later snapshot from the same producer supersedes an earlier one. */
+  | 'snapshot'
+  /** A one-off account of something that just happened; it supersedes nothing. */
+  | 'notice'
+  /** A message another agent addressed to this one. */
+  | 'relay'
+  /** Material lifted out of another session's log, possibly reduced on the way in. */
+  | 'recall'
 ```
 
 ```ts type-equiv

docs/core-data-structures/goal.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write docs/core-data-structures/goal.md
-goal.md: 704a93320cc38d1b9400edc2d9ad2342bc11dccd
-goal.zh.md: 7532bf888651f647686de456e58f54855941f3c0
+goal.md: 8627b927fcff1c32faac0e76356f576bdbb29ba8
+goal.zh.md: f1c3a2e4d65d1efe849aab565e8beb79e0284aae

docs/core-data-structures/goal.md

@@ -103,6 +103,13 @@ Goal state changes use round `0`. A continuation consumer attributes each admitt
 /** Message attribution for durable goal state and continuation rounds. */
 interface GoalMessageSource {
   readonly kind: 'goal'
+  /**
+   * Round-zero state changes are `notice`-form contexts; a continuation round
+   * carries the objective forward as ordinary context and declares no form.
+   */
+  readonly form?: 'notice'
+  /** Present with `form`: one-line account of the mutation. */
+  readonly summary?: string
   readonly goalId: GoalId
   readonly revision: number
   /** Zero for state changes; positive for admitted continuation rounds. */

docs/core-data-structures/goal.zh.md

@@ -103,6 +103,13 @@ interface GoalClearChangeMeta {
 /** Message attribution for durable goal state and continuation rounds. */
 interface GoalMessageSource {
   readonly kind: 'goal'
+  /**
+   * Round-zero state changes are `notice`-form contexts; a continuation round
+   * carries the objective forward as ordinary context and declares no form.
+   */
+  readonly form?: 'notice'
+  /** Present with `form`: one-line account of the mutation. */
+  readonly summary?: string
   readonly goalId: GoalId
   readonly revision: number
   /** Zero for state changes; positive for admitted continuation rounds. */

docs/core-data-structures/subagent.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write docs/core-data-structures/subagent.md
-subagent.md: c5fbf80ae71f99606dd86e38f06a4511b4ae4c73
-subagent.zh.md: 42c1fa7cb10863c1aa4ae975171b901207c08b85
+subagent.md: 956b47cfa85efe7826fbde47d4405d20a6abed6c
+subagent.zh.md: 467fcd35bcde5fd01a2e18efbad862c72d7a4253

docs/core-data-structures/subagent.md

@@ -149,6 +149,8 @@ Final settlement awaits `ctx.sessions.flush(session)` but ignores its participat
 /** Attribution for a model coordinator's follow-up to one of its children. */
 interface CoordinatorMessageSource {
   readonly kind: 'coordinator'
+  /** A message another agent addressed to this one (`relay` context form). */
+  readonly form: 'relay'
   /** Session id of the agent whose tool call produced the follow-up. */
   readonly senderSessionId: SessionId
 }
@@ -182,6 +184,8 @@ An optional continuable-child setup contribution can install scope-local capabil
 /** Durable attribution for a continuable child's explicit parent report. */
 interface SubagentReportMessageSource {
   readonly kind: 'subagent-report'
+  /** A message another agent addressed to this one (`relay` context form). */
+  readonly form: 'relay'
   /** Session id of the reporting child. */
   readonly senderSessionId: SessionId
 }

docs/core-data-structures/subagent.zh.md

@@ -149,6 +149,8 @@ Agent 收件箱是唯一的队列。每条继续执行消息都会成为一个 `
 /** Attribution for a model coordinator's follow-up to one of its children. */
 interface CoordinatorMessageSource {
   readonly kind: 'coordinator'
+  /** A message another agent addressed to this one (`relay` context form). */
+  readonly form: 'relay'
   /** Session id of the agent whose tool call produced the follow-up. */
   readonly senderSessionId: SessionId
 }
@@ -182,6 +184,8 @@ interface ContinuableStart {
 /** Durable attribution for a continuable child's explicit parent report. */
 interface SubagentReportMessageSource {
   readonly kind: 'subagent-report'
+  /** A message another agent addressed to this one (`relay` context form). */
+  readonly form: 'relay'
   /** Session id of the reporting child. */
   readonly senderSessionId: SessionId
 }