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.

packages/goal/goal/src/domain.ts

@@ -61,6 +61,13 @@ export type GoalChangeMeta = GoalSnapshotChangeMeta | GoalClearChangeMeta
 /** Message attribution for durable goal state and continuation rounds. */
 export 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. */

packages/goal/goal/src/index.ts

@@ -23,7 +23,7 @@ import {
   goalChangeRef,
 } from './fold.ts'
 import type { GoalFoldState } from './fold.ts'
-import { renderGoalChange } from './render.ts'
+import { goalChangeSummary, renderGoalChange } from './render.ts'
 import {
   GOAL_CHANGE_VERSION,
   GoalError,
@@ -568,7 +568,15 @@ export class GoalService extends Service {
     try {
       agent.inject(createUserMessage({
         content: renderGoalChange(change),
-        source: { kind: 'goal', goalId: ref.id, revision: ref.revision, round: 0, change },
+        source: {
+          kind: 'goal',
+          goalId: ref.id,
+          revision: ref.revision,
+          round: 0,
+          change,
+          form: 'notice',
+          summary: goalChangeSummary(change),
+        },
       }))
     } catch (error: unknown) {
       const index = cache.pending.indexOf(pending)

packages/goal/goal/src/render.ts

@@ -3,6 +3,18 @@
 import type { ContentBlock } from '@deepseek-ai/dsh-llm'
 import type { GoalChangeMeta } from './domain.ts'
 
+/**
+ * One-line account of a goal mutation for the `notice` form's collapsed row.
+ * @param change - durable goal change carried by the message source.
+ * @returns the operation and, for a surviving goal, its objective.
+ */
+export function goalChangeSummary(change: GoalChangeMeta): string {
+  // The row header already names the producer, so the account does not repeat it.
+  return change.operation === 'clear'
+    ? change.operation
+    : `${change.operation}: ${change.goal.objective}`
+}
+
 /**
  * Render a complete goal snapshot or clear tombstone without hidden prose.
  * @param change - durable goal change carried by the message source.

packages/goal/tool-goal/src/index.ts

@@ -315,7 +315,12 @@ export function apply(ctx: Context, config: Config): void {
           content: args.action === 'complete'
             ? renderWrapupContext(goal.objective)
             : renderWrapupContext(goal.objective, args.blocked_reason as string),
-          source: { kind: 'plugin', plugin: 'tool-goal' },
+          source: {
+            kind: 'plugin',
+            plugin: 'tool-goal',
+            form: 'notice',
+            summary: `${args.action as string}: ${goal.objective}`,
+          },
         }))
       }
       return Promise.resolve(goalValue(goal))

packages/goal/tool-goal/tests/tool-goal.spec.ts

@@ -372,7 +372,12 @@ describe('goal tool state transitions', () => {
     expect(complete.concludesTurn).toBeUndefined()
     const contexts = complete.additionalContexts ?? []
     expect(contexts).toHaveLength(1)
-    expect(contexts[0]?.source).toEqual({ kind: 'plugin', plugin: 'tool-goal' })
+    expect(contexts[0]?.source).toEqual({
+      kind: 'plugin',
+      plugin: 'tool-goal',
+      form: 'notice',
+      summary: 'complete: pause cleanly',
+    })
     const block = contexts[0]?.content[0]
     if (block?.type !== 'text') throw new Error('expected one text wrap-up block')
     expect(block.text).toContain('<goal_complete>')