feat(web): render durable session titles

packages/client/connection/src/client/fixture.ts

@@ -40,7 +40,13 @@ function buildAlphaLog(): SessionEvent[] {
   }
   for (let turn = 0; turn < 60; turn++) {
     push({ type: 'turn/start', data: { turn, trigger: { kind: 'message', source: { kind: 'user' } } } })
-    push({ type: 'user/message', surfaceOp: 'append', data: { content: text(`问题 ${turn}：fixture 历史消息，用于翻页与渲染验收。`), source: { kind: 'user' } } })
+    const userSeq = push({ type: 'user/message', surfaceOp: 'append', data: { content: text(`问题 ${turn}：fixture 历史消息，用于翻页与渲染验收。`), source: { kind: 'user' } } })
+    if (turn === 0) {
+      push({
+        type: 'session/title',
+        data: { title: 'Fixture 历史会话', messageSeqs: [userSeq], source: { kind: 'fallback' } },
+      })
+    }
     if (turn % 9 === 4) {
       push({ type: 'context/message', surfaceOp: 'append', data: { content: text(`[fixture] 上下文注入（turn ${turn}）`), source: { kind: 'plugin', plugin: 'fixture' } } })
     }
@@ -155,6 +161,20 @@ function viewFor(event: SessionEvent, log: readonly SessionEvent[]): ToolEventVi
   return undefined
 }
 
+/** Fold the latest fixture title into the host's control-frame projection. */
+function titleFrameOf(id: SessionId, log: readonly SessionEvent[]): Extract<MuxFrame, { type: 'session/title' }> | undefined {
+  const event = log.findLast(item => (item as { type: string }).type === 'session/title')
+  if (event === undefined) return undefined
+  const titleEvent = event as unknown as { seq: number; time: number; data: { title: string } }
+  return {
+    type: 'session/title',
+    sessionId: id,
+    title: titleEvent.data.title,
+    eventSeq: titleEvent.seq,
+    updatedAt: titleEvent.time,
+  }
+}
+
 /**
  * Message-boundary paging (mirrors the host's paging contract): count
  * maxMessages messages
@@ -294,6 +314,10 @@ export function createFixtureApi(): ApiProxy {
     emitMux(view === undefined
       ? { type: 'session/event', sessionId: id, event }
       : { type: 'session/event', sessionId: id, event, view })
+    if ((event as { type: string }).type === 'session/title') {
+      // The raw title is already in this log, so the latest-title fold must find it.
+      emitMux(titleFrameOf(id, log) as Extract<MuxFrame, { type: 'session/title' }>)
+    }
   }
 
   /** At most one in-flight replay per session; cancel clears it. */
@@ -322,6 +346,12 @@ export function createFixtureApi(): ApiProxy {
     appendUser(id: string, msg: string): void {
       append(sid(id), { type: 'user/message', surfaceOp: 'append', data: { content: text(msg), source: { kind: 'user' } } })
     },
+    /** Append a later durable title revision through the normal raw-event + control-frame path. */
+    appendTitle(id: string, title: string): void {
+      const log = logOf(sid(id))
+      const messageSeqs = log.filter(event => event.type === 'user/message').map(event => event.seq)
+      append(sid(id), { type: 'session/title', data: { title, messageSeqs, source: { kind: 'provider', provider: 'fixture' } } })
+    },
     /** Log append WITHOUT the mux emit: a frame lost in transit — history still serves it, the client must repull. */
     appendSilent(id: string, msg: string): void {
       const log = logOf(sid(id))
@@ -433,6 +463,8 @@ export function createFixtureApi(): ApiProxy {
         for (const s of sessions) {
           if (!s.running) continue
           conn.push({ rpcId: mint(), payload: { type: 'session/subscribed', sessionId: s.sessionId, lastSeq: (logs.get(s.sessionId)?.length ?? 0) - 1 } })
+          const title = titleFrameOf(s.sessionId, logs.get(s.sessionId) ?? [])
+          if (title !== undefined) conn.push({ rpcId: mint(), payload: title })
         }
         conn.push({
           rpcId: pendingApprovalRpcId,

packages/client/connection/tests/fixture.spec.ts

@@ -18,6 +18,7 @@ interface TimingHooks {
   setHistoryDelay(ms: number): void
   failNextHistory(): void
   appendUser(id: string, msg: string): void
+  appendTitle(id: string, title: string): void
   appendSilent(id: string, msg: string): void
   breakStreams(): void
 }
@@ -155,7 +156,7 @@ describe('createFixtureApi', () => {
       const envelopes: RpcRequest<MuxFrame>[] = []
       for await (const envelope of api.events.mux(req({}), abort.signal)) {
         envelopes.push(envelope)
-        if (envelopes.length >= 2) abort.abort()
+        if (envelopes.length >= 3) abort.abort()
       }
       return envelopes
     }
@@ -163,8 +164,9 @@ describe('createFixtureApi', () => {
     const second = await openOnce()
     expect(first[0]?.payload).toMatchObject({ type: 'session/subscribed', sessionId: 'fx-alpha' })
     expect((first[0]?.payload as { lastSeq: number }).lastSeq).toBeGreaterThan(0)
-    expect(first[1]?.payload).toMatchObject({ type: 'approval/requested', toolName: 'dangerous_tool' })
-    expect(second[1]?.rpcId).toBe(first[1]?.rpcId) // stable rpcId across replays (host replay semantics)
+    expect(first[1]?.payload).toMatchObject({ type: 'session/title', sessionId: 'fx-alpha', title: 'Fixture 历史会话' })
+    expect(first[2]?.payload).toMatchObject({ type: 'approval/requested', toolName: 'dangerous_tool' })
+    expect(second[2]?.rpcId).toBe(first[2]?.rpcId) // stable rpcId across replays (host replay semantics)
   })
 
   it('steer with no replay in flight falls through to a fresh queued turn; non-text blocks stringify empty', async () => {
@@ -248,10 +250,15 @@ describe('createFixtureApi', () => {
     await new Promise(resolve => setTimeout(resolve, 10))
     hooks.appendSilent('fx-alpha', '静默丢帧')
     hooks.appendUser('fx-alpha', '正常直播')
+    hooks.appendTitle('fx-alpha', 'Fixture 修订标题')
     await vi.waitFor(() => {
       expect(seen.some(f => f.type === 'session/event' && JSON.stringify(f.event.data).includes('正常直播'))).toBe(true)
+      expect(seen.some(f => f.type === 'session/title' && f.title === 'Fixture 修订标题')).toBe(true)
     })
     expect(seen.some(f => f.type === 'session/event' && JSON.stringify(f.event.data).includes('静默丢帧'))).toBe(false)
+    const rawTitleIndex = seen.findIndex(f => f.type === 'session/event' && (f.event as { type: string }).type === 'session/title')
+    const titleControlIndex = seen.findIndex(f => f.type === 'session/title' && f.title === 'Fixture 修订标题')
+    expect(titleControlIndex).toBe(rawTitleIndex + 1)
     // But history serves the silent event (the client's repull finds it).
     const repull = await api.sessions.history(req({ sessionId: sid('fx-alpha'), maxMessages: 5 }))
     if (!repull.result.ok) throw new Error('repull failed')