feat(chat): 实现多视图滚动位置保存与恢复功能

- 在 App 组件中新增 viewKey，用于标识当前视图
- 通过属性链传递 viewKey 至 MessageList 以区分不同滚动上下文
- MessageList 中新增滚动位置缓存机制，使用 Map 保存各视图的滚动状态
- 在视图切换时自动恢复对应滚动位置，提升用户体验
- 保持消息新增时的自动滚动行为，兼顾视图切换与消息更新场景

web/src/App.tsx

@@ -474,6 +474,13 @@ function App() {
     return result
   }, [messages])
 
+  // 视图标识：用于 MessageList 保存/恢复每个视图的滚动位置
+  const viewKey = useMemo(() => {
+    if (schedulerView) return `scheduler:${schedulerView.jobId}`
+    if (subAgentView) return `subagent:${subAgentView.taskId}`
+    return 'main'
+  }, [schedulerView, subAgentView])
+
   return (
     <div className="flex h-screen flex-col bg-[var(--bg-primary)] text-[var(--text-primary)] overflow-hidden">
       {/* Header */}
@@ -686,6 +693,7 @@ function App() {
               onNavigateToSubAgent={handleNavigateToSubAgent}
               onStop={handleStopExecution}
               showThinking={showThinking}
+              viewKey={viewKey}
               todoPanel={
                 <TodoPanel
                   todos={todos}

web/src/components/Chat/ChatContainer.tsx

@@ -13,6 +13,8 @@ interface ChatContainerProps {
   showThinking?: boolean
   /** 浮动待办面板，绝对定位在消息区域上方 */
   todoPanel?: React.ReactNode
+  /** 视图标识，用于保存/恢复滚动位置 */
+  viewKey?: string
 }
 
 export function ChatContainer({
@@ -25,11 +27,12 @@ export function ChatContainer({
   onStop,
   showThinking = true,
   todoPanel,
+  viewKey,
 }: ChatContainerProps) {
   return (
     <div className="flex h-full flex-col relative">
       <div className="flex-1 overflow-hidden relative">
-        <MessageList messages={messages} onNavigateToSubAgent={onNavigateToSubAgent} showThinking={showThinking} />
+        <MessageList messages={messages} onNavigateToSubAgent={onNavigateToSubAgent} showThinking={showThinking} viewKey={viewKey} />
         {todoPanel}
       </div>
       <MessageInput

web/src/components/Chat/MessageList.tsx

@@ -7,14 +7,22 @@ interface MessageListProps {
   messages: ChatMessage[]
   onNavigateToSubAgent?: (taskId: string, description: string) => void
   showThinking?: boolean
+  /** 视图标识，用于保存/恢复滚动位置。不同视图间切换时保持各自的滚动位置。 */
+  viewKey?: string
 }
 
-export function MessageList({ messages, onNavigateToSubAgent, showThinking = true }: MessageListProps) {
+export function MessageList({ messages, onNavigateToSubAgent, showThinking = true, viewKey }: MessageListProps) {
   const bottomRef = useRef<HTMLDivElement>(null)
   const containerRef = useRef<HTMLDivElement>(null)
   const isAtBottomRef = useRef(true)
   const prevShowBottomRef = useRef(false)
   const prevShowTopRef = useRef(false)
+  const prevViewKeyRef = useRef(viewKey)
+  const viewKeyRef = useRef(viewKey)
+  viewKeyRef.current = viewKey
+
+  // Per-view scroll position memory
+  const scrollPositionsRef = useRef<Map<string, number>>(new Map())
 
   const [showScrollToBottom, setShowScrollToBottom] = useState(false)
   const [showScrollToTop, setShowScrollToTop] = useState(false)
@@ -42,6 +50,12 @@ export function MessageList({ messages, onNavigateToSubAgent, showThinking = tru
     const distanceFromBottom = el.scrollHeight - el.scrollTop - el.clientHeight
     const nearBottom = distanceFromBottom < 120
 
+    // Save scroll position for current view
+    const key = viewKeyRef.current
+    if (key) {
+      scrollPositionsRef.current.set(key, el.scrollTop)
+    }
+
     isAtBottomRef.current = nearBottom
 
     const shouldShowTop = el.scrollTop > el.clientHeight * 0.8
@@ -61,14 +75,36 @@ export function MessageList({ messages, onNavigateToSubAgent, showThinking = tru
     }
   }, [hasNewMessage])
 
-  // ---- auto-scroll: useLayoutEffect runs before browser processes scroll events ----
+  // ---- auto-scroll: handle view switches and message updates ----
 
   useLayoutEffect(() => {
+    const prevKey = prevViewKeyRef.current
+    const viewChanged = prevKey !== viewKey
+    prevViewKeyRef.current = viewKey
+
     if (messages.length === 0) {
       isAtBottomRef.current = true
       return
     }
 
+    if (viewChanged) {
+      // View switched (e.g. breadcrumb navigation): restore saved scroll position
+      const key = viewKey ?? ''
+      const savedPos = scrollPositionsRef.current.get(key)
+      if (savedPos !== undefined && containerRef.current) {
+        containerRef.current.scrollTop = savedPos
+        const el = containerRef.current
+        const distanceFromBottom = el.scrollHeight - el.scrollTop - el.clientHeight
+        isAtBottomRef.current = distanceFromBottom < 120
+        return
+      }
+      // First time viewing this view: scroll to bottom
+      isAtBottomRef.current = true
+      bottomRef.current?.scrollIntoView({ behavior: 'instant' })
+      return
+    }
+
+    // Same view, messages changed: normal auto-scroll logic
     const lastMessage = messages[messages.length - 1]
 
     if (lastMessage.role === 'user' || isAtBottomRef.current) {
@@ -76,7 +112,7 @@ export function MessageList({ messages, onNavigateToSubAgent, showThinking = tru
     } else {
       setHasNewMessage(true)
     }
-  }, [messages])
+  }, [messages, viewKey])
 
   // ---- mount: always scroll to bottom if messages already loaded ----