fix: preserve investigation execution history by round

src/features/agent/api/client.test.ts

@@ -138,6 +138,76 @@ describe("Agent API client sessions", () => {
     await expect(createAgentApiClient("http://agent.local").loadSession("missing")).resolves.toBeNull();
   });
 
+  it("loads a task execution history through its exact task and run binding", async () => {
+    const fetchMock = vi.fn(async (..._args: Parameters<typeof fetch>) => Response.json({
+      id: "execution-session",
+      session_id: "execution-session",
+      title: "南桥管道爆管调查 · 执行记录",
+      purpose: "task_execution",
+      task_id: "50000000-0000-4000-8000-000000000001",
+      created_at: "2026-10-30T01:00:00Z",
+      updated_at: "2026-10-30T01:05:00Z",
+      messages: [{ id: "assistant", role: "assistant", parts: [{ type: "text", text: "调查完成" }] }],
+      is_streaming: false,
+      run_status: "completed"
+    }));
+    vi.stubGlobal("fetch", fetchMock);
+    const client = createAgentApiClient("http://agent.local", {
+      getAccessToken: async () => "token",
+      getProjectId: async () => "project"
+    });
+
+    const loaded = await client.loadTaskExecutionSession(
+      "50000000-0000-4000-8000-000000000001",
+      "70000000-0000-4000-8000-000000000001",
+      "execution-session"
+    );
+
+    expect(loaded).toMatchObject({
+      sessionId: "execution-session",
+      title: "南桥管道爆管调查 · 执行记录",
+      purpose: "task_execution",
+      taskId: "50000000-0000-4000-8000-000000000001",
+      runStatus: "completed"
+    });
+    const url = new URL(String(fetchMock.mock.calls[0]?.[0]));
+    expect(url.pathname).toBe("/api/v1/task/50000000-0000-4000-8000-000000000001/execution-session");
+    expect(url.searchParams.get("run_id")).toBe("70000000-0000-4000-8000-000000000001");
+    expect(url.searchParams.get("session_id")).toBe("execution-session");
+    const headers = new Headers(fetchMock.mock.calls[0]?.[1]?.headers);
+    expect(headers.get("Authorization")).toBe("Bearer token");
+    expect(headers.get("X-Project-Id")).toBe("project");
+  });
+
+  it("creates a debug branch bound to an exact task execution history", async () => {
+    const fetchMock = vi.fn(async (..._args: Parameters<typeof fetch>) => Response.json({
+      session_id: "debug-session",
+      title: "南桥管道爆管调查 · 调试",
+      purpose: "task_collaboration",
+      task_id: "50000000-0000-4000-8000-000000000001",
+      parent_session_id: "execution-session",
+      created: true
+    }, { status: 201 }));
+    vi.stubGlobal("fetch", fetchMock);
+    const client = createAgentApiClient("http://agent.local", {
+      getAccessToken: async () => "token",
+      getProjectId: async () => "project"
+    });
+
+    await expect(client.createTaskExecutionDebugSession(
+      "50000000-0000-4000-8000-000000000001",
+      "70000000-0000-4000-8000-000000000001",
+      "execution-session"
+    )).resolves.toMatchObject({ session_id: "debug-session", purpose: "task_collaboration" });
+
+    const [url, init] = fetchMock.mock.calls[0] ?? [];
+    expect(new URL(String(url)).pathname).toBe("/api/v1/task/50000000-0000-4000-8000-000000000001/execution-session/debug");
+    expect(JSON.parse(String(init?.body))).toEqual({
+      run_id: "70000000-0000-4000-8000-000000000001",
+      session_id: "execution-session"
+    });
+  });
+
   it("falls back when a candidate is not the agent service", async () => {
     const fetchMock = vi
       .fn()

src/features/agent/api/client.ts

@@ -174,6 +174,8 @@ export type AgentApiClient = InteractionRequestApi & {
   moveSessionToTopic: (sessionId: string, topicId: string | null) => Promise<void>;
   loadOlderMessages: (sessionId: string, before: string, signal?: AbortSignal) => Promise<AgentHistoryMessagePage>;
   createTaskCollaborationSession: (taskId: string) => Promise<AgentChatSession>;
+  createTaskExecutionDebugSession: (taskId: string, runId: string, sessionId: string) => Promise<AgentChatSession>;
+  loadTaskExecutionSession: (taskId: string, runId: string, sessionId: string, signal?: AbortSignal) => Promise<AgentLoadedChatSession | null>;
   loadSession: (sessionId: string, options?: { messageLimit?: number; signal?: AbortSignal }) => Promise<AgentLoadedChatSession | null>;
   streamSession: (
     sessionId: string,
@@ -365,6 +367,30 @@ export function createAgentApiClient(
       );
     },
 
+    async createTaskExecutionDebugSession(taskId, runId, sessionId) {
+      return requestJson<AgentChatSession>(
+        `/task/${encodeURIComponent(taskId)}/execution-session/debug`,
+        {
+          method: "POST",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify({ run_id: runId, session_id: sessionId })
+        }
+      );
+    },
+
+    async loadTaskExecutionSession(taskId, runId, sessionId, signal) {
+      const query = new URLSearchParams({ run_id: runId, session_id: sessionId });
+      const response = await request(
+        `/task/${encodeURIComponent(taskId)}/execution-session?${query}`,
+        { signal }
+      );
+      const text = await response.text();
+      const data = text ? JSON.parse(text) : null;
+      if (response.status === 404) return null;
+      if (!response.ok) throw new Error(getResponseErrorMessage(data, response.status));
+      return toLoadedSession(data);
+    },
+
     async getFrontendActionRegistry() {
       return requestJson<unknown>("/frontend-action-registry");
     },