diff --git a/src/routes/chatSessionRoutes.ts b/src/routes/chatSessionRoutes.ts
index d7ba002..5d6b2cc 100644
--- a/src/routes/chatSessionRoutes.ts
+++ b/src/routes/chatSessionRoutes.ts
@@ -54,6 +54,16 @@ const taskExecutionPayloadSchema = z.object({
   workflow: z.string().trim().min(1).max(120).optional(),
 });
 
+const taskExecutionHistoryQuerySchema = z.object({
+  run_id: z.string().uuid(),
+  session_id: z.string().trim().min(1).max(128),
+});
+
+const taskExecutionDebugPayloadSchema = z.object({
+  run_id: z.string().uuid(),
+  session_id: z.string().trim().min(1).max(128),
+}).strict();
+
 const sessionListQuerySchema = z.object({
   purpose: z.enum(["ordinary_chat", "task_execution", "task_collaboration"]).optional(),
   task_id: z.string().uuid().optional(),
@@ -240,6 +250,35 @@ export const registerChatSessionRoutes = (
     }
   };
 
+  const resolveTaskExecutionHistory = async (
+    projectId: string,
+    credential: ProductCredential,
+    taskId: string,
+    runId: string,
+    sessionId: string,
+  ) => {
+    const validationSessionId = `task-history-access-${crypto.randomUUID()}`;
+    let taskTitle: string;
+    bindOperationalTaskCredential(validationSessionId, credential);
+    try {
+      taskTitle = (await operationalTaskClient.getAgentContext(validationSessionId, taskId)).task.title;
+    } finally {
+      releaseOperationalTaskCredential(validationSessionId);
+      clearOperationalTaskLease(validationSessionId);
+    }
+
+    const record = await sessionMetadataStore.getTaskExecutionBinding(
+      projectId,
+      taskId,
+      runId,
+      sessionId,
+    );
+    if (!record) return null;
+    const state = await sessionUiStateStore.read(toSessionUiStateContext(record));
+    if (!state) return null;
+    return { record, state, taskTitle };
+  };
+
   chatRouter.post("/session", async (req, res) => {
     const parsed = createSessionPayloadSchema.safeParse(req.body ?? {});
     if (!parsed.success) {
@@ -413,6 +452,152 @@ export const registerChatSessionRoutes = (
     });
   });
 
+  chatRouter.get("/task/:task_id/execution-session", async (req, res) => {
+    const taskId = z.string().uuid().safeParse(req.params.task_id);
+    const query = taskExecutionHistoryQuerySchema.safeParse(req.query);
+    if (!taskId.success || !query.success) {
+      res.status(400).json({ message: "valid task_id, run_id and session_id are required" });
+      return;
+    }
+    const authContext = getLocalAgentContext(req);
+    const credential = getTrustedProductCredential(req);
+    if (!authContext.projectId) {
+      res.status(403).json({ message: "task execution history requires project context" });
+      return;
+    }
+    if (!credential) {
+      res.status(401).json({ message: "task execution history requires product credentials" });
+      return;
+    }
+
+    let history: Awaited<ReturnType<typeof resolveTaskExecutionHistory>>;
+    try {
+      history = await resolveTaskExecutionHistory(
+        authContext.projectId,
+        credential,
+        taskId.data,
+        query.data.run_id,
+        query.data.session_id,
+      );
+    } catch (error) {
+      res.status(error && typeof error === "object" && "status" in error && typeof error.status === "number" ? error.status : 502).json({
+        message: error instanceof Error ? error.message : "task access validation failed",
+      });
+      return;
+    }
+    if (!history) {
+      res.status(404).json({ message: "task execution session not found" });
+      return;
+    }
+    const { record, state, taskTitle } = history;
+    const runStatus = getSessionRunStatus(record.sessionId);
+    res.setHeader("Cache-Control", "no-store");
+    res.json({
+      id: record.sessionId,
+      session_id: record.sessionId,
+      title: `${taskTitle} · 执行记录`,
+      created_at: record.createdAt,
+      updated_at: record.updatedAt,
+      status: record.status,
+      messages: await withInteractionReplies(record, state.messages ?? []),
+      execution_plans: state.executionPlans ?? [],
+      is_streaming: runStatus === "running",
+      run_status: runStatus,
+      purpose: "task_execution",
+      task_id: record.taskId,
+      read_only: true,
+    });
+  });
+
+  chatRouter.post("/task/:task_id/execution-session/debug", async (req, res) => {
+    const taskId = z.string().uuid().safeParse(req.params.task_id);
+    const payload = taskExecutionDebugPayloadSchema.safeParse(req.body);
+    if (!taskId.success || !payload.success) {
+      res.status(400).json({ message: "valid task_id, run_id and session_id are required" });
+      return;
+    }
+    const authContext = getLocalAgentContext(req);
+    const credential = getTrustedProductCredential(req);
+    if (!authContext.projectId) {
+      res.status(403).json({ message: "task execution debugging requires project context" });
+      return;
+    }
+    if (!credential) {
+      res.status(401).json({ message: "task execution debugging requires product credentials" });
+      return;
+    }
+
+    let history: Awaited<ReturnType<typeof resolveTaskExecutionHistory>>;
+    try {
+      history = await resolveTaskExecutionHistory(
+        authContext.projectId,
+        credential,
+        taskId.data,
+        payload.data.run_id,
+        payload.data.session_id,
+      );
+    } catch (error) {
+      res.status(error && typeof error === "object" && "status" in error && typeof error.status === "number" ? error.status : 502).json({
+        message: error instanceof Error ? error.message : "task access validation failed",
+      });
+      return;
+    }
+    if (!history) {
+      res.status(404).json({ message: "task execution session not found" });
+      return;
+    }
+
+    const metadataContext = {
+      actorKey: authContext.actorKey,
+      projectId: authContext.projectId,
+      projectKey: authContext.projectKey,
+      userId: authContext.userId,
+    };
+    const existing = (await sessionMetadataStore.list(metadataContext, {
+      purpose: "task_collaboration",
+      taskId: taskId.data,
+    })).find((record) => record.parentSessionId === history.record.sessionId);
+    if (existing) {
+      res.json({
+        session_id: existing.sessionId,
+        title: existing.title,
+        purpose: readPurpose(existing),
+        task_id: existing.taskId,
+        parent_session_id: existing.parentSessionId,
+        created: false,
+        status: existing.status,
+      });
+      return;
+    }
+
+    const runtimeSession = await runtime.createSession(undefined, metadataContext);
+    const { record } = await sessionMetadataStore.ensure({
+      ...metadataContext,
+      sessionId: runtimeSession.id,
+      parentSessionId: history.record.sessionId,
+      purpose: "task_collaboration",
+      taskId: taskId.data,
+    });
+    const titled = await sessionMetadataStore.touch(record, { title: `${history.taskTitle} · 调试` });
+    const messages = await withInteractionReplies(history.record, history.state.messages ?? []);
+    await sessionUiStateStore.write(
+      toSessionUiStateContext(titled),
+      buildForkedSessionUiState({ messages }, {
+        keepMessageCount: messages.length,
+        targetSessionId: titled.sessionId,
+      }),
+    );
+    res.status(201).json({
+      session_id: titled.sessionId,
+      title: titled.title,
+      purpose: readPurpose(titled),
+      task_id: titled.taskId,
+      parent_session_id: titled.parentSessionId,
+      created: true,
+      status: titled.status,
+    });
+  });
+
   chatRouter.post("/task-executions", async (req, res) => {
     const parsed = taskExecutionPayloadSchema.safeParse(req.body);
     if (!parsed.success) {
diff --git a/tests/routes/task-collaboration-sessions.test.ts b/tests/routes/task-collaboration-sessions.test.ts
index ede857f..f280ba6 100644
--- a/tests/routes/task-collaboration-sessions.test.ts
+++ b/tests/routes/task-collaboration-sessions.test.ts
@@ -14,6 +14,7 @@ const http = globalThis.fetch;
 const projectId = "10000000-0000-4000-8000-000000000001";
 const firstTask = "50000000-0000-4000-8000-000000000001";
 const secondTask = "50000000-0000-4000-8000-000000000002";
+const firstRun = "70000000-0000-4000-8000-000000000001";
 let root: string | undefined;
 let server: Server | undefined;
 
@@ -75,9 +76,15 @@ async function fixture() {
   await new Promise<void>((resolve) => server!.once("listening", resolve));
   const address = server.address();
   if (!address || typeof address === "string") throw new Error("missing server address");
-  const request = async (path: string, method = "GET", user = "owner") => {
+  const request = async (path: string, method = "GET", user = "owner", body?: unknown) => {
     const response = await http(`http://127.0.0.1:${address.port}/api/v1${path}`, {
-      method, headers: { Authorization: `Bearer ${user}`, "X-Project-Id": projectId },
+      method,
+      headers: {
+        Authorization: `Bearer ${user}`,
+        "X-Project-Id": projectId,
+        ...(body === undefined ? {} : { "Content-Type": "application/json" }),
+      },
+      body: body === undefined ? undefined : JSON.stringify(body),
     });
     return { status: response.status, body: await response.json() as Record<string, any> };
   };
@@ -87,7 +94,20 @@ async function fixture() {
     await states.write({ ...context, sessionId }, { sessionId, messages: [], isTitleManuallyEdited: manuallyEdited });
     return titled;
   };
-  return { request, seed, sessions, context, taskReads, setAvailable: (value: boolean) => { available = value; },
+  const seedExecution = async (sessionId: string, taskId: string, runId: string) => {
+    const workerContext = {
+      actorKey: toActorKey("service:operational-worker"),
+      projectKey: context.projectKey,
+      projectId,
+      userId: "operational-worker",
+    };
+    await sessions.ensure({ ...workerContext, sessionId, taskId, runId, purpose: "task_execution" });
+    await states.write({ ...workerContext, sessionId }, { sessionId, messages: [
+      { id: "execution-user", role: "user", parts: [{ type: "text", text: "执行后台调查任务" }] },
+      { id: "execution-assistant", role: "assistant", parts: [{ type: "text", text: "已完成压力与流量证据核对" }] },
+    ] });
+  };
+  return { request, seed, seedExecution, sessions, context, taskReads, setAvailable: (value: boolean) => { available = value; },
     setTaskReadHook: (hook: () => Promise<unknown>) => { onTaskRead = hook; },
     waitForTitleAbort: () => { waitForAbort = true; }, didAbort: () => observedAbort };
 }
@@ -106,6 +126,72 @@ it("names new collaboration sessions after their verified tasks", async () => {
   expect(taskReads).toHaveLength(2);
 });
 
+it("opens an exact task execution binding as a read-only cross-actor history", async () => {
+  const { request, seedExecution } = await fixture();
+  await seedExecution("worker-execution", firstTask, firstRun);
+
+  expect((await request("/session/worker-execution")).status).toBe(404);
+  const result = await request(`/task/${firstTask}/execution-session?run_id=${firstRun}&session_id=worker-execution`);
+
+  expect(result.status).toBe(200);
+  expect(result.body).toMatchObject({
+    session_id: "worker-execution",
+    title: "南桥管道爆管调查 · 执行记录",
+    purpose: "task_execution",
+    task_id: firstTask,
+    read_only: true,
+    is_streaming: false,
+  });
+  expect(result.body.messages.map((message: { id: string }) => message.id)).toEqual([
+    "execution-user",
+    "execution-assistant",
+  ]);
+  expect((await request(`/task/${firstTask}/execution-session?run_id=${secondTask}&session_id=worker-execution`)).status).toBe(404);
+  expect((await request(`/task/${secondTask}/execution-session?run_id=${firstRun}&session_id=worker-execution`)).status).toBe(404);
+});
+
+it("creates one user-owned debug branch from an exact task execution history", async () => {
+  const { request, seedExecution } = await fixture();
+  await seedExecution("worker-execution", firstTask, firstRun);
+
+  const first = await request(`/task/${firstTask}/execution-session/debug`, "POST", "owner", {
+    run_id: firstRun,
+    session_id: "worker-execution",
+  });
+
+  expect(first.status).toBe(201);
+  expect(first.body).toMatchObject({
+    title: "南桥管道爆管调查 · 调试",
+    purpose: "task_collaboration",
+    task_id: firstTask,
+    parent_session_id: "worker-execution",
+    created: true,
+  });
+  const debug = await request(`/session/${first.body.session_id}`);
+  expect(debug.body.messages.map((message: { id: string }) => message.id)).toEqual([
+    "execution-user",
+    "execution-assistant",
+  ]);
+
+  const reused = await request(`/task/${firstTask}/execution-session/debug`, "POST", "owner", {
+    run_id: firstRun,
+    session_id: "worker-execution",
+  });
+  expect(reused.status).toBe(200);
+  expect(reused.body).toMatchObject({ session_id: first.body.session_id, created: false });
+});
+
+it("validates current task access before revealing an execution history", async () => {
+  const { request, seedExecution, setAvailable } = await fixture();
+  await seedExecution("protected-execution", firstTask, firstRun);
+  setAvailable(false);
+
+  const result = await request(`/task/${firstTask}/execution-session?run_id=${firstRun}&session_id=protected-execution`);
+
+  expect(result.status).toBe(503);
+  expect(result.body.message).toBe("task context unavailable");
+});
+
 it("repairs returned legacy history without changing timestamps or custom names, then searches the repaired titles", async () => {
   const { request, seed, sessions, context, taskReads } = await fixture();
   const first = await seed("legacy-first", firstTask, "任务协作");