Collapse process output the moment the final reply starts streaming (Cursor-style)

Why: 流式期间思考/工具/中间轮解说与最终回复混排在中栏，用户难以扫读答复；参考 Cursor：回复开始输出时过程即时折叠，可手动展开回看。
Evidence: npx tsc --noEmit 通过；npx vitest run 20/20（新增 test/live.test.ts：分桶、除末桶外 process 标记、终态同构）。
Impact: LiveState.text 改为按 delta index 分桶的 texts；responding 阶段过程折叠、acting 重展开；终态新增 >800 字长回复折叠（CF0）；无契约变更。
Refs: 任务卡 feature/chat-process-split-r1；配套 backend 提交 0e76f59（工具轮文本 process=true）。

node_modules

@@ -0,0 +1 @@
+/home/weichen/projects/Agent-System-Dev/modules/frontend/node_modules

src/components/Conversation.tsx

@@ -4,6 +4,7 @@ import { useEffect, useMemo, useRef, useState } from 'react'
 import { marked } from 'marked'
 import { api } from '../api'
 import { store, useStore, activeRun, type LiveState, type ContextObs } from '../store'
+import { liveToMessage } from '../live'
 import type { Message, Part, HITLCard } from '../contracts'
 import { UIRenderer, InlineConfirmCard, hasOpenConfirm } from '@ui'
 import { docBridge } from './Workbench'
@@ -82,6 +83,23 @@ function ProcessCollapse({ parts }: { parts: Part[] }) {
   )
 }
 
+// 长回复折叠阈值（CF0）：终态后超长正文收成摘要行，点击展开全文；live 期间全文可见。
+const LONG_REPLY_CHARS = 800
+
+function LongReplyCollapse({ text }: { text: string }) {
+  return (
+    <details className="process-collapse long-reply">
+      <summary>
+        <span>📄 长回复</span>
+        <span>{text.length} 字（点击展开）</span>
+      </summary>
+      <div className="body">
+        <div className="part-text" dangerouslySetInnerHTML={{ __html: marked.parse(text) }} />
+      </div>
+    </details>
+  )
+}
+
 function AssistantMessage({ msg, live }: { msg: Message; live?: LiveState | null }) {
   const autoCollapse = useStore(s => s.ui.autoCollapseProcess)
   const ctxObs = useStore(s => (msg.runId ? s.contextObs[msg.runId] : undefined))
@@ -92,8 +110,11 @@ function AssistantMessage({ msg, live }: { msg: Message; live?: LiveState | null
     return out
   }, [parts])
 
-  // 流式中：过程部件实时展开；run 终态后：按偏好折叠为摘要行（可回看）。
+  // 流式期间：工具/思考阶段过程实时展开；一旦进入 responding（最终回复开始流式）
-  const showProcessInline = live || !autoCollapse
+  // 立即折叠过程，只显式显示回复（Cursor 式）；工具恢复（acting）时重新展开。
+  // run 终态后：按偏好折叠为摘要行（可回看）。
+  const showProcessInline = live ? live.phase !== 'responding' : !autoCollapse
+  const lastContentIdx = split.content.length - 1
   return (
     <div className="msg assistant">
       <div className="msg-role">
@@ -104,29 +125,20 @@ function AssistantMessage({ msg, live }: { msg: Message; live?: LiveState | null
       {split.process.length > 0 && (showProcessInline
         ? split.process.map((p, i) => <div className="part" key={i}><PartView part={p} live={!!live} /></div>)
         : <ProcessCollapse parts={split.process} />)}
-      {split.content.map((p, i) => <div className="part" key={i}><PartView part={p} live={!!(live && i === split.content.length - 1 && p.type === 'text')} /></div>)}
+      {split.content.map((p, i) => {
+        // CF0：非 live 的超长文本部件折叠为摘要行；live 与短文本不受影响。
+        if (!live && p.type === 'text' && (p.text?.length ?? 0) > LONG_REPLY_CHARS)
+          return <LongReplyCollapse key={i} text={p.text ?? ''} />
+        return <div className="part" key={i}>
+          <PartView part={p} live={!!(live && i === lastContentIdx && p.type === 'text')} />
+        </div>
+      })}
       {live && <LiveAgentNotes live={live} />}
       {!live && ctxObs && <ContextObsView obs={ctxObs} />}
     </div>
   )
 }
 
-// live 投影：run 进行中没有已落库的助手消息，把 LiveState 合成为同构的临时消息
-// 复用 AssistantMessage 渲染（思考/工具/文本实时上屏）；run 终态对账后由真消息替代。
-function liveToMessage(live: LiveState): Message {
-  const parts: Part[] = []
-  if (live.thinking) parts.push({ type: 'thinking', text: live.thinking, process: true })
-  for (const tc of live.toolCalls) {
-    parts.push({ type: 'tool_call', process: true, toolCall: { id: '', name: tc.name } })
-    if (tc.status !== undefined) {
-      parts.push({ type: 'tool_result', process: true, toolCall: { id: '', name: tc.name },
-        toolResult: { callId: '', status: tc.status === 'error' ? 'error' : 'ok', summary: tc.summary } })
-    }
-  }
-  if (live.text) parts.push({ type: 'text', text: live.text })
-  return { id: `live:${live.runId}`, conversationId: '', role: 'assistant', runId: live.runId, parts, createdAt: '' }
-}
-
 // 上下文组装观测（4.10/4.17）：模型实际看到什么、裁了什么——可解释性入口。
 function ContextObsView({ obs }: { obs: ContextObs }) {
   return (
@@ -238,7 +250,7 @@ export function Conversation() {
 
   useEffect(() => {
     bodyRef.current?.scrollTo({ top: bodyRef.current.scrollHeight })
-  }, [messages.length, live?.text, live?.thinking, live?.toolCalls.length, live?.phase, activeHitl.length])
+  }, [messages.length, live?.texts, live?.thinking, live?.toolCalls.length, live?.phase, activeHitl.length])
 
   const send = async () => {
     if (!text.trim() && attachmentIds.length === 0) return

src/live.ts

@@ -0,0 +1,36 @@
+// live 流式投影纯逻辑（中栏过程/回复分离）：按 delta index 分桶、合成临时消息。
+// 新文本桶只在新轮开启（必经工具轮），故除最后一桶外均为工具轮过程解说（process）；
+// 最后一桶是正在流式的回复——与落库消息的 process 语义同构，终态对账无跳变。
+import type { Message, Part } from './contracts'
+import type { LiveState } from './store'
+
+export interface TextBucket { index: number; text: string }
+
+// applyTextDelta 把一段正文增量并入桶序列：index 与末桶相同则追加，否则开新桶。
+export function applyTextDelta(buckets: TextBucket[], index: number, delta: string): TextBucket[] {
+  const last = buckets[buckets.length - 1]
+  if (last && last.index === index) {
+    const out = buckets.slice()
+    out[out.length - 1] = { index, text: last.text + delta }
+    return out
+  }
+  return [...buckets, { index, text: delta }]
+}
+
+// liveToMessage：run 进行中没有已落库的助手消息，把 LiveState 合成同构临时消息，
+// 复用 AssistantMessage 渲染（思考/工具/文本实时上屏）；终态对账后由真消息替代。
+export function liveToMessage(live: LiveState): Message {
+  const parts: Part[] = []
+  if (live.thinking) parts.push({ type: 'thinking', text: live.thinking, process: true })
+  for (let i = 0; i < live.texts.length; i++) {
+    parts.push({ type: 'text', text: live.texts[i].text, process: i < live.texts.length - 1 || undefined })
+  }
+  for (const tc of live.toolCalls) {
+    parts.push({ type: 'tool_call', process: true, toolCall: { id: '', name: tc.name } })
+    if (tc.status !== undefined) {
+      parts.push({ type: 'tool_result', process: true, toolCall: { id: '', name: tc.name },
+        toolResult: { callId: '', status: tc.status === 'error' ? 'error' : 'ok', summary: tc.summary } })
+    }
+  }
+  return { id: `live:${live.runId}`, conversationId: '', role: 'assistant', runId: live.runId, parts, createdAt: '' }
+}

src/store.ts

@@ -2,6 +2,7 @@
 // useSyncExternalStore 驱动；live 流式部件为会话内临时态，run 终态后由消息树对账收敛。
 import { useSyncExternalStore } from 'react'
 import { api, connectEvents } from './api'
+import { applyTextDelta } from './live'
 import type {
   Project, Conversation, Message, Run, Artifact, HITLCard, PlanSnapshot, TodoList,
   AgentProfile, StreamEvent, PluginPanel, ActivityCard,
@@ -17,7 +18,9 @@ export interface LiveState {
   runId: string
   phase: string
   thinking: string
-  text: string
+  // 按 delta index 分桶的文本：新桶只在新轮开启（必经工具轮），故除最后一桶外
+  // 均为工具轮过程解说（process）；最后一桶是正在流式的回复。
+  texts: { index: number; text: string }[]
   toolCalls: { name: string; status?: string; summary?: string }[]
   agentNotes: Record<string, string>
   startedAt: number
@@ -253,7 +256,7 @@ export const store = {
     switch (e.type) {
       case 'message.delta': {
         const p = e.payload as { index: number; text: string }
-        set({ live: touchLive(e.runId ?? '', l => { l.text += p.text }) })
+        set({ live: touchLive(e.runId ?? '', l => { l.texts = applyTextDelta(l.texts, p.index, p.text) }) })
         break
       }
       case 'thinking.delta': {
@@ -367,7 +370,7 @@ export const store = {
         // 竞态保护：POST 返回前 SSE 事件可能已先行到达并累积（同 run），
         // 此时保留已累积的 live，只补挂用户消息；否则初始化空 live。
         if (!state.live || state.live.runId !== out.run.id) {
-          set({ live: { runId: out.run.id, phase: 'thinking', thinking: '', text: '', toolCalls: [], agentNotes: {}, startedAt: Date.now() } })
+          set({ live: { runId: out.run.id, phase: 'thinking', thinking: '', texts: [], toolCalls: [], agentNotes: {}, startedAt: Date.now() } })
         }
         set({ messages: [...state.messages, out.message] })
         store.connectIfNeeded()
@@ -501,7 +504,7 @@ export const store = {
 }
 
 function touchLive(_runId: string, mutate: (l: LiveState) => void): LiveState | null {
-  const base = state.live ?? { runId: _runId, phase: 'thinking', thinking: '', text: '', toolCalls: [], agentNotes: {}, startedAt: Date.now() }
+  const base = state.live ?? { runId: _runId, phase: 'thinking', thinking: '', texts: [], toolCalls: [], agentNotes: {}, startedAt: Date.now() }
   const next: LiveState = { ...base, toolCalls: [...base.toolCalls], agentNotes: { ...base.agentNotes } }
   mutate(next)
   return next

test/live.test.ts

@@ -0,0 +1,48 @@
+// live 流式投影纯逻辑测试（中栏过程/回复分离）：分桶、process 标记、终态同构。
+import { describe, it, expect } from 'vitest'
+import { applyTextDelta, liveToMessage, type TextBucket } from '../src/live'
+import type { LiveState } from '../src/store'
+
+function live(over: Partial<LiveState> = {}): LiveState {
+  return { runId: 'r1', phase: 'thinking', thinking: '', texts: [], toolCalls: [], agentNotes: {}, startedAt: 0, ...over }
+}
+
+describe('applyTextDelta', () => {
+  it('appends to the last bucket when index matches', () => {
+    let b: TextBucket[] = []
+    b = applyTextDelta(b, 0, '先查')
+    b = applyTextDelta(b, 0, '一下')
+    expect(b).toEqual([{ index: 0, text: '先查一下' }])
+  })
+  it('opens a new bucket when index advances (new turn)', () => {
+    let b: TextBucket[] = applyTextDelta([], 0, '解说')
+    b = applyTextDelta(b, 1, '最终')
+    b = applyTextDelta(b, 1, '回复')
+    expect(b).toEqual([{ index: 0, text: '解说' }, { index: 1, text: '最终回复' }])
+  })
+})
+
+describe('liveToMessage', () => {
+  it('marks all but the last text bucket as process (tool-turn commentary)', () => {
+    const msg = liveToMessage(live({
+      thinking: '思考',
+      texts: [{ index: 0, text: '我先更新待办。' }, { index: 1, text: '完成了。' }],
+      toolCalls: [{ name: 'update_todos', status: 'ok' }],
+    }))
+    const texts = msg.parts.filter(p => p.type === 'text')
+    expect(texts.map(p => p.process)).toEqual([true, undefined])
+    expect(texts.map(p => p.text)).toEqual(['我先更新待办。', '完成了。'])
+  })
+  it('single bucket (final turn only) carries no process flag', () => {
+    const msg = liveToMessage(live({ texts: [{ index: 0, text: '直接回答' }] }))
+    expect(msg.parts.filter(p => p.type === 'text').map(p => p.process)).toEqual([undefined])
+  })
+  it('thinking and tool parts are always process', () => {
+    const msg = liveToMessage(live({
+      thinking: '想',
+      texts: [{ index: 0, text: '答' }],
+      toolCalls: [{ name: 'web_search', status: 'ok', summary: '命中' }],
+    }))
+    for (const p of msg.parts.filter(p => p.type !== 'text')) expect(p.process).toBe(true)
+  })
+})