diff --git a/docs/agent-chat-ui-design.md b/docs/agent-chat-ui-design.md
index 7faddf6..9b48575 100644
--- a/docs/agent-chat-ui-design.md
+++ b/docs/agent-chat-ui-design.md
@@ -34,6 +34,8 @@ Agent 相关弹窗、面板及菜单统一保持本地 shadcn/ui 设计，具体
 
 普通用户的阅读路径为：确认当前项目，提出问题，阅读回答，核查来源，再按需要定位地图或补充资料。审批和队列在有实际内容时出现，历史与处理过程按需展开。
 
+任务协作以对应任务名称作为初始标题，随后由 Agent 根据任务名称与对话内容生成具体标题；生成失败或仅返回通用名称时保留现有标题。“任务协作”仅作为历史列表中的类型标记。旧的通用标题随历史分页和详情读取逐步补齐，保留手动重命名及原有顺序；标题更新不重载消息或打断当前对话。
+
 运行中的输入区使用一个外框：顶部显示待处理消息，正文最多预览两行，溢出时提供“展开全文”；每条消息只保留正文、简短的处理方式和一个菜单。编辑、处理方式切换、关闭排队统一进入该菜单。底栏在生成期间用“引导 / 排队”替代暂时不能切换的模型选择，生成完成后恢复模型选择。右下角的同一个按钮在运行且输入为空时停止，有内容时发送追加消息，空闲时发送新消息。输入正文默认高 64px，随多行内容自动增高至视口高度的 24%，最多 160px；超出后在输入区内部滚动，清空后恢复 64px；队列单独限制滚动高度，工作台支持的窄屏和短窗口保留可见的输入操作。
 
 ## 1. 交互参考
diff --git a/src/features/workbench/hooks/use-workbench-agent.ts b/src/features/workbench/hooks/use-workbench-agent.ts
index 8b4c774..c4d937a 100644
--- a/src/features/workbench/hooks/use-workbench-agent.ts
+++ b/src/features/workbench/hooks/use-workbench-agent.ts
@@ -62,6 +62,7 @@ import { agentRuntimes, createAgentRuntime, mergeHistoryMessages, resumeAgentRun
   type AgentReadingPosition, type AgentSessionRuntime } from "./agent-session-runtime";
 
 const AGENT_PANEL_COLLAPSE_MS = 180;
+const LEGACY_COLLABORATION_TITLES = new Set(["任务协作", "任务协作问答", "新对话"]);
 
 type UseWorkbenchAgentOptions = {
   onUiEnvelope: (payload: UIEnvelopePayload, sessionId: string) => Promise<void> | void;
@@ -334,6 +335,20 @@ export function useWorkbenchAgent({
     // Ownership changes only when selecting a different runtime, never on token updates.
     if (resources.activeAgent !== runtime) activateRuntime(runtime);
   }, [activateRuntime, resources, runtime]);
+  useEffect(() => {
+    let changed = false;
+    const summaries = new Map(history.sessions.map((summary) => [summary.id, summary]));
+    for (const entry of agentRuntimes(resources)) {
+      if (entry.scope !== scopeKey || entry.purpose !== "task_collaboration"
+        || !LEGACY_COLLABORATION_TITLES.has(entry.title)) continue;
+      const summary = entry.sessionId ? summaries.get(entry.sessionId) : undefined;
+      if (!summary || LEGACY_COLLABORATION_TITLES.has(summary.title)) continue;
+      entry.title = summary.title;
+      if (resources.activeAgent === entry) setSessionTitle(summary.title);
+      changed = true;
+    }
+    if (changed) resources.notify();
+  }, [history.sessions, resources, scopeKey]);
   useEffect(() => {
     chatRef.current = chat;
   }, [chat]);
@@ -642,6 +657,7 @@ export function useWorkbenchAgent({
     if (!normalizedTaskId) throw new Error("工况任务 ID 不能为空。");
     const context = agentTaskDiscussionContextSchema.parse(discussion?.context ?? {});
     const sourceDraft = resources.activeAgent?.draft ?? promptDraftRef.current;
+    const titlesBeforeOpen = new Map(agentRuntimes(resources).filter((entry) => entry.scope === projectScopeKey).map((entry) => [entry, entry.title]));
     const projectClient = createAgentApiClient(undefined, { getAccessToken: getWorkbenchTokenProvider(getAccessToken), getProjectId });
     const collaboration = await projectClient.createTaskCollaborationSession(normalizedTaskId);
     const id = collaboration.session_id || collaboration.id;
@@ -654,6 +670,10 @@ export function useWorkbenchAgent({
         createWorkbenchAgentTransport(projectClient, getAccessToken, getProjectId), loaded);
       if (loaded.isStreaming || loaded.runStatus === "running") resumeAgentRuntime(resources, target);
     }
+    const titleBeforeOpen = titlesBeforeOpen.get(target);
+    const canApplyTitle = titleBeforeOpen === undefined
+      ? LEGACY_COLLABORATION_TITLES.has(target.title) : target.title === titleBeforeOpen;
+    if (collaboration.title?.trim() && canApplyTitle) target.title = collaboration.title.trim();
     target.taskDiscussion = { context, reportGeneration: discussion?.reportGeneration };
     if (!target.draft.trim() && target !== resources.activeAgent) target.draft = sourceDraft;
     if (discussion?.prompt?.trim()) target.draft = target.draft.trim() ? `${target.draft}\n\n${discussion.prompt.trim()}` : discussion.prompt.trim();
diff --git a/tests/browser/agent-history.e2e.ts b/tests/browser/agent-history.e2e.ts
index 230f66f..10da416 100644
--- a/tests/browser/agent-history.e2e.ts
+++ b/tests/browser/agent-history.e2e.ts
@@ -5,6 +5,33 @@ import { createServer, type ServerResponse } from "node:http";
 import { responseFixtureWriter } from "./support/responses-fixture";
 import { expectThemeColor } from "./support/theme-colors";
 
+test("history repairs a cached collaboration title without reloading its conversation", async ({ page }, testInfo) => {
+  await page.emulateMedia({ reducedMotion: "reduce" });
+  await mockWorkbenchContext(page);
+  const session = { session_id: "collaboration-50000000-0000-4000-8000-000000000001",
+    purpose: "task_collaboration", title: "任务协作", created_at: Date.now(), updated_at: Date.now() };
+  await mockAgentApi(page, { sessions: [session] });
+  let loads = 0;
+  page.on("request", (request) => {
+    if (request.method() === "GET" && new URL(request.url()).pathname.endsWith(`/session/${session.session_id}`)) loads += 1;
+  });
+  await page.goto("/", { waitUntil: "domcontentloaded" });
+  await page.getByRole("button", { name: /展开 Agent 助手面板/ }).click();
+  const panel = page.getByRole("complementary", { name: "Agent 命令面板" });
+  await panel.getByRole("button", { name: "打开 Agent 历史记录" }).click();
+  const dialog = page.getByRole("dialog", { name: "历史对话" });
+  await dialog.locator("button.agent-history-session-trigger").filter({ hasText: "任务协作" }).click();
+  await expect(panel.locator(".agent-chat-context-bar > p")).toHaveText("任务协作");
+  session.title = "南桥管道爆管调查";
+  await panel.getByRole("button", { name: "打开 Agent 历史记录" }).click();
+  await dialog.getByRole("button", { name: "刷新 Agent 历史记录" }).click();
+  await expect(dialog.locator("button.agent-history-session-trigger").filter({ hasText: session.title })).toBeVisible();
+  await page.keyboard.press("Escape");
+  await expect(panel.locator(".agent-chat-context-bar > p")).toHaveText(session.title);
+  expect(loads).toBe(1);
+  await panel.screenshot({ path: testInfo.outputPath("collaboration-title-repaired.png"), animations: "disabled" });
+});
+
 async function prepare(page: Page) {
   await page.emulateMedia({ reducedMotion: "reduce" });
   await mockWorkbenchContext(page);
diff --git a/tests/browser/investigation-main-chat.e2e.ts b/tests/browser/investigation-main-chat.e2e.ts
index c3efc9d..a652837 100644
--- a/tests/browser/investigation-main-chat.e2e.ts
+++ b/tests/browser/investigation-main-chat.e2e.ts
@@ -102,6 +102,22 @@ test("单一协作入口展示任务引用，保留草稿且仅手动发送，
   await page.emulateMedia({ reducedMotion: "reduce" });
   await mockWorkbenchContext(page);
   await mockAgentApi(page, { sessions: [{ session_id: "ordinary-main", title: "供水核查主聊天", purpose: "ordinary_chat", created_at: now, updated_at: now }] });
+  let collaborationOpens = 0;
+  const renamedCollaborationTitle = "异味投诉现场复核记录";
+  let finishReopen!: () => void;
+  const reopenGate = new Promise<void>((resolve) => { finishReopen = resolve; });
+  await page.route(`**/task/${taskId}/collaboration/session`, async (route) => {
+    collaborationOpens += 1;
+    if (collaborationOpens === 2) await reopenGate;
+    return route.fulfill({ headers: { "Access-Control-Allow-Origin": "*" }, json: {
+      session_id: `collaboration-${taskId}`, purpose: "task_collaboration", task_id: taskId,
+      title: collaborationOpens <= 2 ? task.title : renamedCollaborationTitle,
+      created: collaborationOpens === 1, status: "active",
+    } });
+  });
+  await page.route(`**/session/collaboration-${taskId}/title`, (route) => route.fulfill({
+    headers: { "Access-Control-Allow-Origin": "*" }, json: { id: `collaboration-${taskId}`, title: route.request().postDataJSON().title },
+  }));
   let submitted = 0;
   let inboxReads = 0;
   let incoming = false;
@@ -146,7 +162,7 @@ test("单一协作入口展示任务引用，保留草稿且仅手动发送，
   await expect(feed.getByRole("button", { name: "Agent 协作", exact: true })).toHaveAttribute("title", "打开调查协作对话，引用此任务，不会直接发送。");
   await feed.screenshot({ path: testInfo.outputPath("investigation-entry-desktop.png") });
   await feed.getByRole("button", { name: "Agent 协作", exact: true }).click();
-  await expect(agent.getByText("任务协作问答", { exact: true }).first()).toBeVisible();
+  await expect(agent.locator(".agent-chat-context-bar > p")).toHaveText(task.title);
   const reference = agent.getByRole("group", { name: "对话引用" });
   await expect(reference).toContainText("居民异味投诉调查");
   await expect(reference).toContainText("第 1 轮 · 报告第 3 版");
@@ -156,6 +172,18 @@ test("单一协作入口展示任务引用，保留草稿且仅手动发送，
   await expect(prompt).toBeFocused();
   expect(submitted).toBe(0);
   await feed.getByRole("button", { name: "Agent 协作", exact: true }).click();
+  await expect.poll(() => collaborationOpens).toBe(2);
+  await agent.getByRole("button", { name: "打开 Agent 历史记录" }).click();
+  const renameDialog = page.getByRole("dialog", { name: "历史对话" });
+  await renameDialog.getByRole("button", { name: `会话操作：${task.title}` }).click();
+  await page.getByRole("menuitem", { name: "重命名对话", exact: true }).click();
+  await renameDialog.getByRole("textbox", { name: "会话标题", exact: true }).fill(renamedCollaborationTitle);
+  await renameDialog.getByRole("button", { name: "保存对话标题" }).click();
+  await expect(renameDialog.locator("button.agent-history-session-trigger").filter({ hasText: renamedCollaborationTitle })).toBeVisible();
+  await page.keyboard.press("Escape");
+  finishReopen();
+  await expect(prompt).toBeFocused();
+  await expect(agent.locator(".agent-chat-context-bar > p")).toHaveText(renamedCollaborationTitle);
   await expect(prompt).toBeFocused();
   await expect(prompt).toHaveValue("保留的现场补充草稿");
   await feed.getByLabel("主要依据").getByRole("button", { name: "围绕此证据提问" }).click();
@@ -200,6 +228,7 @@ test("单一协作入口展示任务引用，保留草稿且仅手动发送，
   await expect(mobileAgent.getByRole("button", { name: "停止 Agent 分析" })).toHaveCount(0);
   incoming = true;
   await mobileAgent.getByRole("button", { name: "打开 Agent 历史记录" }).click();
+  await expect(page.getByRole("dialog", { name: "历史对话" }).locator("button.agent-history-session-trigger").filter({ hasText: renamedCollaborationTitle })).toBeVisible();
   await page.getByRole("dialog", { name: "历史对话" }).getByRole("button", { name: /^供水核查主聊天/ }).click();
   await expect(mobileAgent.getByRole("group", { name: "对话引用" })).toHaveCount(0);
   await expect(mobileAgent.getByText("已核对上游监测，请补充现场采样记录。")).toBeVisible();