perf(ui-trajectory): reuse finalized stream projections

packages/client/runtime/tests/partial.spec.ts

@@ -41,6 +41,12 @@ describe('PartialAccumulator', () => {
     expect(acc.toPartial().blocks).toEqual([{ kind: 'reasoning', text: '思考' }])
   })
 
+  it('continues from a materialized history prefix', () => {
+    const acc = new PartialAccumulator(1, 0, [{ kind: 'text', text: '已有' }])
+    acc.push(chunk({ type: 'text-delta', index: 0, text: '增量' }))
+    expect(acc.toPartial().blocks).toEqual([{ kind: 'text', text: '已有增量' }])
+  })
+
   it('folds tool-call deltas: first id pins callId, late name overrides, argsRaw concatenates', () => {
     const acc = new PartialAccumulator(1, 0)
     acc.push(chunk({ type: 'tool-call-delta', index: 0, id: 'c1', argumentsDelta: '{"a"' }))

packages/client/runtime/tests/session-history-source.spec.ts

@@ -1,4 +1,4 @@
-import { describe, expect, it } from 'vitest'
+import { afterEach, describe, expect, it, vi } from 'vitest'
 import type { SessionEvent } from '@deepseek-ai/dsh-session/types'
 import type { SessionId } from '@deepseek-ai/dsh-client-connection/client'
 import { SessionHistorySource } from '../src/client/session-history/source.ts'
@@ -7,6 +7,10 @@ import { entries, ev, plainTurn } from './event-script.ts'
 
 const SID = 'history-s1' as SessionId
 
+afterEach(() => {
+  vi.unstubAllGlobals()
+})
+
 function histResponse(events: SessionEvent[], hasMore = false) {
   return Promise.resolve(ok({ events: entries(events) as never[], hasMore }))
 }
@@ -52,6 +56,71 @@ describe('SessionHistorySource', () => {
       .toEqual([1, 3, 6])
   })
 
+  it('publishes multiple assistant chunks once per browser frame', async () => {
+    const api = new FakeApiClient()
+    api.onHistory = () => histResponse(plainTurn(0, 0, '问', '答'))
+    const source = new SessionHistorySource(SID, api)
+    await source.loadAll()
+    const frames: FrameRequestCallback[] = []
+    vi.stubGlobal('requestAnimationFrame', (callback: FrameRequestCallback) => {
+      frames.push(callback)
+      return frames.length
+    })
+    let notifications = 0
+    const unsubscribe = source.subscribe(() => { notifications++ })
+    const before = source.getSnapshot().inspection
+    const finalizedNodes = before.eventNodes
+    const requests = before.requests
+    const contexts = before.contexts
+
+    for (const event of [
+      ev.chunkStart(6, 1),
+      ev.chunkText(7, 1, 'stream '),
+      ev.chunkText(8, 1, 'content'),
+    ]) {
+      source.handleMuxFrame({
+        type: 'session/event',
+        sessionId: SID,
+        event,
+      })
+    }
+
+    expect(frames).toHaveLength(1)
+    expect(notifications).toBe(0)
+    frames[0]?.(0)
+    await Promise.resolve()
+
+    expect(notifications).toBe(1)
+    const streamed = source.getSnapshot().inspection
+    expect(streamed.eventNodes).toBe(finalizedNodes)
+    expect(streamed.requests).toBe(requests)
+    expect(streamed.contexts).toBe(contexts)
+    expect(streamed.partial?.blocks).toEqual([
+      { kind: 'text', text: 'stream content' },
+    ])
+
+    source.handleMuxFrame({
+      type: 'session/event',
+      sessionId: SID,
+      event: ev.chunkText(9, 1, ' then final'),
+    })
+    source.handleMuxFrame({
+      type: 'session/event',
+      sessionId: SID,
+      event: ev.assistant(10, 1, 'stream content then final'),
+    })
+    await Promise.resolve()
+
+    expect(notifications).toBe(2)
+    const finalized = source.getSnapshot().inspection
+    expect(finalized.eventNodes).not.toBe(finalizedNodes)
+    expect(finalized.partial).toBeNull()
+    frames[1]?.(0)
+    await Promise.resolve()
+    expect(notifications).toBe(2)
+    unsubscribe()
+  })
+
   it('stops loading when an older page fails to advance', async () => {
     const api = new FakeApiClient()
     api.onHistory = payload => payload.beforeSeq === undefined