diff --git a/web/src/App.tsx b/web/src/App.tsx
index 465ee4b6..5560596e 100644
--- a/web/src/App.tsx
+++ b/web/src/App.tsx
@@ -1708,12 +1708,19 @@ export default function App() {
 
   // 驱动一次真实后端 SSE 流式对话尝试：气泡状态机 pending → streaming_status → completed/failed/cancelled。
   // 闲聊路径在无 client_turn_id 幂等前禁止自动重放 POST；失败仅展示手动「重试」。
+  type StreamAttemptOpts = {
+    userMsgId?: string;
+    clientTurnId?: string;
+    quote?: QuotedMessage;
+  };
+
   const runStreamAttempt = (
     userText: string,
     asstId: string,
     attemptIndex: number,
-    quote?: QuotedMessage
+    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();
@@ -1734,7 +1741,7 @@ export default function App() {
           setIsThinking(false);
           return;
         }
-        runStreamAttempt(userText, asstId, attemptIndex + 1, quote);
+        runStreamAttempt(userText, asstId, attemptIndex + 1, opts);
       }, delayMs);
     };
 
@@ -1771,6 +1778,14 @@ export default function App() {
     });
     setIsThinking(true);
 
+    const bindUserServerId = (serverId: number) => {
+      if (!opts?.userMsgId) return;
+      chatWindow.replaceMessageServerId(opts.userMsgId, serverId);
+      setMessages((prev) =>
+        prev.map((m) => (m.id === opts.userMsgId ? { ...m, serverId } : m))
+      );
+    };
+
     streamChat(
       {
         session_id: activeSessionId,
@@ -1782,12 +1797,20 @@ export default function App() {
         user_name: currentUser.name,
         user_role: currentDocRole,
         message: userText,
+        client_turn_id: opts?.clientTurnId,
         quote: quote,
       },
       {
         onEvent: (ev) => {
           if (controller.signal.aborted || settled) return;
           switch (ev.type) {
+            case 'turn_ack': {
+              const userServerId = ev.turn?.user_message_id ?? ev.user_message_id;
+              if (typeof userServerId === 'number' && userServerId > 0) {
+                bindUserServerId(userServerId);
+              }
+              break;
+            }
             case 'phase':
             case 'status': {
               const label = ev.phase?.message || ev.status?.message;
@@ -1805,7 +1828,11 @@ export default function App() {
             }
             case 'done': {
               settled = true;
-              const serverMsgId = ev.message_id || (ev as any).messageId || ev.done?.message_id;
+              const userServerId = ev.done?.user_message_id ?? ev.user_message_id;
+              const serverMsgId = ev.done?.message_id ?? ev.message_id ?? (ev as { messageId?: number }).messageId;
+              if (typeof userServerId === 'number' && userServerId > 0) {
+                bindUserServerId(userServerId);
+              }
               if (typeof serverMsgId === 'number' && serverMsgId > 0) {
                 chatWindow.replaceMessageServerId(asstId, serverMsgId);
               }
@@ -1824,7 +1851,8 @@ export default function App() {
           }
         },
       },
-      controller.signal
+      controller.signal,
+      opts?.clientTurnId ? { idempotencyKey: opts.clientTurnId } : undefined
     ).catch((_err) => {
       if (settled) return;
       if (controller.signal.aborted) {
@@ -2104,8 +2132,11 @@ export default function App() {
       }
     }
 
+    const clientTurnId = crypto.randomUUID();
     const userMsg: ChatMessage = {
       id: 'msg-' + Date.now(),
+      clientTurnId,
+      clientMessageId: `${clientTurnId}:user`,
       sessionId: activeSessionId,
       role: 'user',
       authorName: currentUser.name,
@@ -2211,6 +2242,8 @@ export default function App() {
       const asstId = 'ast-' + Date.now();
       const placeholder: ChatMessage = {
         id: asstId,
+        clientTurnId,
+        clientMessageId: `${clientTurnId}:assistant`,
         sessionId: activeSessionId,
         role: 'assistant',
         authorName: '项目助手',
@@ -2221,7 +2254,11 @@ export default function App() {
         sourceUserMessageId: userMsg.id,
       };
       setMessages((prev) => [...prev, placeholder]);
-      runStreamAttempt(text, asstId, 0, quotes && quotes.length > 0 ? quotes[0] : undefined);
+      runStreamAttempt(text, asstId, 0, {
+        userMsgId: userMsg.id,
+        clientTurnId,
+        quote: quotes && quotes.length > 0 ? quotes[0] : undefined,
+      });
       return;
     }
 
diff --git a/web/src/api/chatStream.ts b/web/src/api/chatStream.ts
index 4bebb2b9..165debad 100644
--- a/web/src/api/chatStream.ts
+++ b/web/src/api/chatStream.ts
@@ -33,6 +33,12 @@ export type StreamEvent = {
     workspace_id?: string;
     actions?: string[];
   };
+  turn?: {
+    client_turn_id?: string;
+    user_message_id?: number;
+    status?: string;
+    duplicate?: boolean;
+  };
   message_id?: number;
   user_message_id?: number;
   content_revision?: number;
@@ -131,10 +137,18 @@ export async function streamChat(
     onRequestId?: (id: string) => void;
   },
   signal?: AbortSignal,
+  options?: { idempotencyKey?: string },
 ): Promise<void> {
+  const headers: Record<string, string> = {
+    'Content-Type': 'application/json',
+    Accept: 'text/event-stream',
+  };
+  if (options?.idempotencyKey) {
+    headers['Idempotency-Key'] = options.idempotencyKey;
+  }
   const resp = await fetch('/api/v1/chat/stream', {
     method: 'POST',
-    headers: { 'Content-Type': 'application/json', Accept: 'text/event-stream' },
+    headers,
     body: JSON.stringify(body),
     signal,
   });
diff --git a/web/src/api/chatWindow.ts b/web/src/api/chatWindow.ts
index 991eb254..ff276079 100644
--- a/web/src/api/chatWindow.ts
+++ b/web/src/api/chatWindow.ts
@@ -62,6 +62,8 @@ export function mapRecordToMessage(r: RawChatMessageRecord): ChatMessage {
   const msgId = meta.client_id || (r.id ? `msg-${r.id}` : `msg-tmp-${Date.now()}-${Math.random().toString(36).substring(2, 6)}`);
   return {
     id: msgId,
+    clientTurnId: meta.client_turn_id || undefined,
+    clientMessageId: meta.client_id || undefined,
     serverId: r.id,
     sessionId: r.session_id,
     role: r.role,
diff --git a/web/src/engine/messageIdentity.ts b/web/src/engine/messageIdentity.ts
new file mode 100644
index 00000000..82df6ea3
--- /dev/null
+++ b/web/src/engine/messageIdentity.ts
@@ -0,0 +1,79 @@
+import type { ChatMessage } from '../types/workbench';
+
+/** 收集消息的所有可对账身份键 */
+export function getMessageKeys(m: ChatMessage): string[] {
+  const keys: string[] = [];
+  if (m.clientTurnId) {
+    keys.push(`turn:${m.clientTurnId}:${m.role}`);
+  }
+  if (m.clientMessageId) {
+    keys.push(`client:${m.clientMessageId}`);
+  }
+  keys.push(`id:${m.id}`);
+  if (m.serverId) {
+    keys.push(`server:${m.serverId}`);
+  }
+  return keys;
+}
+
+/** 判断两条消息是否代表同一条物理消息 */
+export function isSameMessage(a: ChatMessage, b: ChatMessage): boolean {
+  if (a.sessionId !== b.sessionId || a.role !== b.role) {
+    return false;
+  }
+  if (a.clientTurnId && b.clientTurnId && a.clientTurnId === b.clientTurnId) {
+    return true;
+  }
+  if (a.serverId && b.serverId && a.serverId === b.serverId) {
+    return true;
+  }
+  if (a.clientMessageId && b.clientMessageId && a.clientMessageId === b.clientMessageId) {
+    return true;
+  }
+  return false;
+}
+
+/** 构建历史 bucket 中已有消息的身份键集合 */
+export function buildExistingMessageKeySet(messages: ChatMessage[]): Set<string> {
+  const keys = new Set<string>();
+  for (const m of messages) {
+    for (const k of getMessageKeys(m)) {
+      keys.add(k);
+    }
+  }
+  return keys;
+}
+
+/** live 消息是否已在历史中（按身份对账，而非仅 m.id） */
+export function isLiveMessageInHistory(
+  live: ChatMessage,
+  historyMessages: ChatMessage[],
+): boolean {
+  return historyMessages.some((h) => isSameMessage(live, h));
+}
+
+/** 过滤出尚未出现在历史中的 live 消息 */
+export function filterPendingLiveMessages(
+  liveMessages: ChatMessage[],
+  historyMessages: ChatMessage[],
+): ChatMessage[] {
+  return liveMessages.filter((m) => !isLiveMessageInHistory(m, historyMessages));
+}
+
+/** 用 live 流状态覆盖历史快照中的同一条消息 */
+export function mergeLiveOverHistory(
+  history: ChatMessage,
+  live: ChatMessage,
+): ChatMessage {
+  if (!isSameMessage(history, live)) {
+    return history;
+  }
+  return {
+    ...history,
+    ...live,
+    id: history.id,
+    serverId: live.serverId ?? history.serverId,
+    clientTurnId: live.clientTurnId ?? history.clientTurnId,
+    clientMessageId: live.clientMessageId ?? history.clientMessageId,
+  };
+}
diff --git a/web/src/hooks/useChatWindow.ts b/web/src/hooks/useChatWindow.ts
index ac409b2e..2bdb4c03 100644
--- a/web/src/hooks/useChatWindow.ts
+++ b/web/src/hooks/useChatWindow.ts
@@ -11,6 +11,11 @@ import {
   saveSessionDraft,
 } from '../data/storage';
 import { enrichMessagesWithCategories } from '../engine/categoryHelper';
+import {
+  filterPendingLiveMessages,
+  isLiveMessageInHistory,
+  mergeLiveOverHistory,
+} from '../engine/messageIdentity';
 
 export type WindowPhase =
   | 'loading_window'
@@ -420,15 +425,8 @@ export function useChatWindow({
     }
 
     const todayStr = getTodayKey();
-    const existingMsgIds = new Set<string>();
-    for (const b of dayStack) {
-      for (const m of b.messages) {
-        existingMsgIds.add(m.id);
-        if (m.serverId) existingMsgIds.add(`msg-${m.serverId}`);
-      }
-    }
-
-    const pendingLive = liveMessages.filter((m) => !existingMsgIds.has(m.id));
+    const historyMessages = dayStack.flatMap((b) => b.messages);
+    const pendingLive = filterPendingLiveMessages(liveMessages, historyMessages);
 
     if (dayStack.length === 0) {
       return [
@@ -445,22 +443,22 @@ export function useChatWindow({
     }
 
     if (pendingLive.length === 0) {
-      const liveMap = new Map(liveMessages.map((m) => [m.id, m]));
       let hasUpdate = false;
       const updatedBuckets = dayStack.map((b) => {
         let bucketChanged = false;
         const newMsgs = b.messages.map((m) => {
-          const liveM = liveMap.get(m.id);
+          const liveM = liveMessages.find((live) => isLiveMessageInHistory(live, [m]));
           if (
             liveM &&
             (liveM.content !== m.content ||
               liveM.status !== m.status ||
               liveM.livePhaseLabel !== m.livePhaseLabel ||
-              liveM.errorInfo !== m.errorInfo)
+              liveM.errorInfo !== m.errorInfo ||
+              liveM.serverId !== m.serverId)
           ) {
             bucketChanged = true;
             hasUpdate = true;
-            return { ...m, ...liveM };
+            return mergeLiveOverHistory(m, liveM);
           }
           return m;
         });
diff --git a/web/src/types/workbench.ts b/web/src/types/workbench.ts
index bccaa367..fe73c50f 100644
--- a/web/src/types/workbench.ts
+++ b/web/src/types/workbench.ts
@@ -121,6 +121,16 @@ export interface ChatErrorInfo {
   actions: Array<'retry' | 'continue' | 'restart'>;
 }
 
+/**
+ * 任务输入材料（对应后端 bizdev.MaterialInput）。
+ * content 为文件原始内容的 Base64 字符串（后端 JSON 反序列化 []byte 时自动解码）。
+ * 仅文本类格式会填充 content；二进制格式 content 留空，仅传文件名作来源注记。
+ */
+export type TaskRunMaterial = {
+  filename: string;
+  content: string; // Base64 编码的文件内容
+};
+
 /** 长任务运行上下文：触发 / 重试 / 重新开始时重发请求所需的最小参数集 */
 export type TaskRunContext = {
   taskKey: string;
@@ -131,6 +141,8 @@ export type TaskRunContext = {
   targetMarket?: string;
   userId?: number;
   projectId?: number;
+  /** 用户上传的参考文档材料，注入任务工作区 materials_text/ 目录 */
+  materials?: TaskRunMaterial[];
 };
 
 export interface ChatMessage {
@@ -163,6 +175,11 @@ export interface ChatMessage {
   /** P2: 最近一次任务成功/收尾时的工作区目录（done.workspace_id） */
   taskWorkspaceId?: string;
 
+  /** 客户端回合 ID（一次发送的用户+助手共享） */
+  clientTurnId?: string;
+  /** 客户端消息 ID（用户/助手各自稳定 ID） */
+  clientMessageId?: string;
+
   /** P0: 历史归档与导航扩展 */
   serverId?: number;
   dayKey?: string;