diff --git a/web/src/App.tsx b/web/src/App.tsx
index 5560596e..7e75a6f8 100644
--- a/web/src/App.tsx
+++ b/web/src/App.tsx
@@ -100,8 +100,6 @@ import {
   saveSessions,
   loadActiveSessionId,
   saveActiveSessionId,
-  loadMessages,
-  saveMessages,
   loadDeliverables,
   saveDeliverables,
   loadRoles,
@@ -118,6 +116,8 @@ import {
   buildPrivateSessionId,
 } from './data/storage';
 import { useChatWindow } from './hooks/useChatWindow';
+import { useTurnRuntime } from './hooks/useTurnRuntime';
+import { fetchChatTurnStatus } from './api/chatTurn';
 import { CategoryFilterBar } from './components/history/CategoryFilterBar';
 import { HistoryCalendar } from './components/history/HistoryCalendar';
 import { ChatSearchModal } from './components/history/ChatSearchModal';
@@ -1301,16 +1301,12 @@ export default function App() {
     patchBlockId?: string;
   } | null>(null);
 
-  // 消息流与思考脉冲 (支持 localStorage 持久化与项目会话严格隔离)
-  const [isThinking, setIsThinking] = useState(false);
-  const [messages, setMessages] = useState<ChatMessage[]>(() => loadMessages());
-  // 真实后端 SSE 流式对话：当前活跃请求的中止句柄 (支持停止与自动重试取消)
-  const streamAbortRef = useRef<AbortController | null>(null);
+  // 消息流：权威来源为服务端窗口；不再全量持久化到 localStorage
+  const [messages, setMessages] = useState<ChatMessage[]>([]);
 
-  // 自动持久化消息流
   useEffect(() => {
-    saveMessages(messages);
-  }, [messages]);
+    void migrateAndClearLegacyMessages();
+  }, []);
 
   // 基于当前激活的项目会话严格隔离对话记录
   const currentSessionMessages = useMemo(() => {
@@ -1318,6 +1314,10 @@ export default function App() {
   }, [messages, activeSessionId]);
 
   // P0: 会话按日窗口状态机 (处理首屏拉取、瞬时落底、触顶加载补偿)
+  const turnRuntime = useTurnRuntime(activeSessionId);
+  const [taskThinking, setTaskThinking] = useState(false);
+  const isThinking = turnRuntime.isThinking || taskThinking;
+
   const chatWindow = useChatWindow({
     sessionId: activeSessionId,
     liveMessages: currentSessionMessages,
@@ -1721,12 +1721,21 @@ export default function App() {
     opts?: StreamAttemptOpts
   ) => {
     const quote = opts?.quote;
-    // 同一时刻只允许一个活跃流：新尝试前中止上一个 (若存在)
-    streamAbortRef.current?.abort();
     const controller = new AbortController();
-    streamAbortRef.current = controller;
+    const streamSessionId = activeSessionId;
+    if (opts?.clientTurnId) {
+      turnRuntime.registerTurn({
+        clientTurnId: opts.clientTurnId,
+        sessionId: streamSessionId,
+        userMsgId: opts.userMsgId || '',
+        asstId,
+        status: 'pending',
+        controller,
+        startedAt: Date.now(),
+      });
+    }
 
-    const currentProj = sessions.find((s) => s.sessionId === activeSessionId);
+    const currentProj = sessions.find((s) => s.sessionId === streamSessionId);
     let accumulated = '';
     let settled = false;
 
@@ -1738,13 +1747,21 @@ export default function App() {
       setTimeout(() => {
         if (controller.signal.aborted) {
           updateAsst({ status: 'cancelled', livePhaseLabel: undefined });
-          setIsThinking(false);
+          if (opts?.clientTurnId) {
+            turnRuntime.updateTurnStatus(streamSessionId, opts.clientTurnId, 'cancelled');
+          }
           return;
         }
         runStreamAttempt(userText, asstId, attemptIndex + 1, opts);
       }, delayMs);
     };
 
+    const finishTurn = (status: 'completed' | 'failed' | 'cancelled') => {
+      if (opts?.clientTurnId) {
+        turnRuntime.updateTurnStatus(streamSessionId, opts.clientTurnId, status);
+      }
+    };
+
     const failOrRetry = (info: ChatErrorInfo) => {
       settled = true;
       if (shouldAutoRetryChat(info, attemptIndex)) {
@@ -1767,7 +1784,7 @@ export default function App() {
         },
         livePhaseLabel: undefined,
       });
-      setIsThinking(false);
+      finishTurn('failed');
     };
 
     updateAsst({
@@ -1776,7 +1793,9 @@ export default function App() {
       content: '',
       errorInfo: undefined,
     });
-    setIsThinking(true);
+    if (opts?.clientTurnId) {
+      turnRuntime.updateTurnStatus(streamSessionId, opts.clientTurnId, 'pending');
+    }
 
     const bindUserServerId = (serverId: number) => {
       if (!opts?.userMsgId) return;
@@ -1788,7 +1807,7 @@ export default function App() {
 
     streamChat(
       {
-        session_id: activeSessionId,
+        session_id: streamSessionId,
         user_id: currentUser.id,
         project_id: currentProj?.projectId || currentProjectId || 1,
         project_name: currentProj?.title || '肌骨超声AI辅助诊断系统',
@@ -1815,11 +1834,17 @@ export default function App() {
             case 'status': {
               const label = ev.phase?.message || ev.status?.message;
               updateAsst({ status: 'streaming_status', livePhaseLabel: label || '助手正在处理…' });
+              if (opts?.clientTurnId) {
+                turnRuntime.updateTurnStatus(streamSessionId, opts.clientTurnId, 'streaming');
+              }
               break;
             }
             case 'delta': {
               accumulated += ev.delta || '';
               updateAsst({ status: 'streaming_status', content: accumulated });
+              if (opts?.clientTurnId) {
+                turnRuntime.updateTurnStatus(streamSessionId, opts.clientTurnId, 'streaming');
+              }
               break;
             }
             case 'error': {
@@ -1843,7 +1868,7 @@ export default function App() {
                 serverId: typeof serverMsgId === 'number' ? serverMsgId : undefined,
                 exportCapability: exportCap,
               });
-              setIsThinking(false);
+              finishTurn('completed');
               break;
             }
             default:
@@ -1853,18 +1878,48 @@ export default function App() {
       },
       controller.signal,
       opts?.clientTurnId ? { idempotencyKey: opts.clientTurnId } : undefined
-    ).catch((_err) => {
+    ).catch(async (_err) => {
       if (settled) return;
       if (controller.signal.aborted) {
         updateAsst({ status: 'cancelled', livePhaseLabel: undefined });
-        setIsThinking(false);
+        finishTurn('cancelled');
         return;
       }
-      // fetch/网络层抛出：合成瞬态错误，走与后端 error 事件一致的自动重试路径
+      if (opts?.clientTurnId) {
+        try {
+          const turnStatus = await fetchChatTurnStatus(streamSessionId, opts.clientTurnId);
+          if (turnStatus?.status === 'completed' && turnStatus.assistantMessageId) {
+            settled = true;
+            if (turnStatus.userMessageId) bindUserServerId(turnStatus.userMessageId);
+            chatWindow.replaceMessageServerId(asstId, turnStatus.assistantMessageId);
+            updateAsst({
+              status: 'completed',
+              livePhaseLabel: undefined,
+              serverId: turnStatus.assistantMessageId,
+            });
+            finishTurn('completed');
+            return;
+          }
+          if (turnStatus?.status === 'processing') {
+            updateAsst({
+              status: 'streaming_status',
+              livePhaseLabel: '连接中断，服务端仍在处理…',
+            });
+            if (opts?.clientTurnId) {
+              turnRuntime.updateTurnStatus(streamSessionId, opts.clientTurnId, 'streaming');
+            }
+            return;
+          }
+        } catch {
+          // fall through to structured failure
+        }
+      }
       failOrRetry(buildNetworkErrorInfo());
     });
   };
 
+  const taskStreamAbortRef = useRef<AbortController | null>(null);
+
   // P2：长任务尝试模式。'run' 新任务 | 'resume' 续跑失败工作区 | 'restart' 按原意图新工作区
   const runTaskAttempt = (
     task: TaskRunContext,
@@ -1873,10 +1928,9 @@ export default function App() {
     attemptIndex: number,
     opts?: { phaseEvents?: PhaseEvent[]; workDir?: string }
   ) => {
-    // 同一时刻只允许一个活跃流：新尝试前中止上一个 (若存在)
-    streamAbortRef.current?.abort();
+    taskStreamAbortRef.current?.abort();
     const controller = new AbortController();
-    streamAbortRef.current = controller;
+    taskStreamAbortRef.current = controller;
 
     let accumulated = '';
     let settled = false;
@@ -1891,7 +1945,7 @@ export default function App() {
       setTimeout(() => {
         if (controller.signal.aborted) {
           patchAsst({ status: 'cancelled', livePhaseLabel: undefined });
-          setIsThinking(false);
+          setTaskThinking(false);
           return;
         }
         runTaskAttempt(task, asstId, mode, attemptIndex + 1, opts);
@@ -1910,7 +1964,7 @@ export default function App() {
         return;
       }
       patchAsst({ status: 'failed', errorInfo: info, livePhaseLabel: undefined });
-      setIsThinking(false);
+      setTaskThinking(false);
     };
 
     // 等待态：resume 保留已有 phaseEvents 续接；run/restart 重置正文与步骤条
@@ -1921,7 +1975,7 @@ export default function App() {
       errorInfo: undefined,
       ...(mode === 'resume' ? {} : { content: '', phaseEvents: [], taskWorkspaceId: undefined }),
     });
-    setIsThinking(true);
+    setTaskThinking(true);
 
     const body =
       mode === 'resume' && opts?.workDir
@@ -1973,7 +2027,7 @@ export default function App() {
                 livePhaseLabel: undefined,
                 taskWorkspaceId: ev.done?.workspace_id,
               });
-              setIsThinking(false);
+              setTaskThinking(false);
               break;
             }
             default:
@@ -1986,7 +2040,7 @@ export default function App() {
       if (settled) return;
       if (controller.signal.aborted) {
         patchAsst({ status: 'cancelled', livePhaseLabel: undefined });
-        setIsThinking(false);
+        setTaskThinking(false);
         return;
       }
       // fetch/网络层抛出：合成瞬态错误，走与后端 error 事件一致的自动重试路径
@@ -2024,12 +2078,16 @@ export default function App() {
       : undefined;
     const originalText = sourceMsg?.content?.trim();
     if (!originalText) return;
-    runStreamAttempt(originalText, messageId, 0);
+    runStreamAttempt(originalText, messageId, 0, {
+      userMsgId: sourceMsg?.id,
+      clientTurnId: target.clientTurnId || sourceMsg?.clientTurnId,
+    });
   };
 
-  // 用户主动停止：中止当前流式请求，级联取消后续自动重试
+  // 用户主动停止：仅中止当前 session 的活跃 turn
   const handleStopStreaming = () => {
-    streamAbortRef.current?.abort();
+    turnRuntime.abortActiveSessionTurns();
+    taskStreamAbortRef.current?.abort();
   };
 
   // 发送消息与对话驱动双轨逻辑
@@ -2262,10 +2320,10 @@ export default function App() {
       return;
     }
 
-    setIsThinking(true);
+    setTaskThinking(true);
 
     setTimeout(() => {
-      setIsThinking(false);
+      setTaskThinking(false);
 
       // 1. 用户要求助手生成新文档/测算/推演/备忘 (默认自动归档至【我的私密生成】，保护隐私)
       if (isGenDocShortcut) {
diff --git a/web/src/api/chatTurn.ts b/web/src/api/chatTurn.ts
new file mode 100644
index 00000000..03f46cf9
--- /dev/null
+++ b/web/src/api/chatTurn.ts
@@ -0,0 +1,30 @@
+export type ChatTurnStatus = {
+  sessionId: string;
+  clientTurnId: string;
+  status: string;
+  userMessageId?: number;
+  assistantMessageId?: number;
+  attemptCount?: number;
+};
+
+export async function fetchChatTurnStatus(
+  sessionId: string,
+  clientTurnId: string,
+  signal?: AbortSignal,
+): Promise<ChatTurnStatus | null> {
+  const url = `/api/v1/chat/turns/${encodeURIComponent(clientTurnId)}?session_id=${encodeURIComponent(sessionId)}`;
+  const res = await fetch(url, { signal });
+  if (res.status === 404) return null;
+  if (!res.ok) {
+    throw new Error(`fetchChatTurnStatus failed: HTTP ${res.status}`);
+  }
+  const raw = await res.json();
+  return {
+    sessionId: raw.session_id,
+    clientTurnId: raw.client_turn_id,
+    status: raw.status,
+    userMessageId: raw.user_message_id,
+    assistantMessageId: raw.assistant_message_id,
+    attemptCount: raw.attempt_count,
+  };
+}