fix: harden journal repair, task detach, subagent prompts, and login cancel

.changeset/codex-login-denied-cancelled.md

@@ -0,0 +1,5 @@
+---
+"@pymodel/pythinker-code": patch
+---
+
+Report a denied OpenAI Codex sign-in as cancelled instead of asking for the redirect URL.

.changeset/subagent-turn-prompts.md

@@ -0,0 +1,5 @@
+---
+"@pymodel/pythinker-code": patch
+---
+
+Show the prompt that started a subagent turn in the transcript.

.changeset/task-detach-action.md

@@ -0,0 +1,5 @@
+---
+"@pymodel/pythinker-code": minor
+---
+
+Add a task detach action to the server API. Call `POST /api/v1/sessions/{session_id}/tasks/{task_id}:detach` to move a running foreground task to the background.

.changeset/vscode-duplicated-stream-events.md

@@ -0,0 +1,5 @@
+---
+"pythinker": patch
+---
+
+Fix duplicated streaming output when a session is opened twice at the same time.

.changeset/wire-journal-repair-retry.md

@@ -0,0 +1,5 @@
+---
+"@pymodel/pythinker-code": patch
+---
+
+Retry a failed session journal repair before writing new records, so no message is appended behind a corrupted tail.

apps/pythinker-code/dist-web/.web-bundle-manifest.json

@@ -1,4 +1,4 @@
 {
-  "sourceHash": "d84e17f04092f5fb9afa9f4d323b614d3945ec8e33abbbc92f5793ad2c30959e",
+  "sourceHash": "aa9ad464f74ddd042d5435d29ed27bac364c25274ede0eade5d39cc7593d0eb6",
   "sourceFileCount": 404
 }

apps/vscode/src/runtime/pythinker-runtime.ts

@@ -48,6 +48,7 @@ export class PythinkerRuntime {
   private readonly log: PythinkerRuntimeOptions["log"];
   private readonly sessions = new Map<string, SessionRuntime>();
   private readonly sessionByView = new Map<string, string>();
+  private readonly viewChains = new Map<string, Promise<void>>();
   private readonly pendingPermissionByView = new Map<string, PermissionMode>();
   private closed = false;
 
@@ -101,6 +102,10 @@ export class PythinkerRuntime {
   }
 
   async openSession(options: OpenSessionOptions): Promise<SessionRuntime> {
+    return this.serializeView(options.webviewId, () => this.openSessionInner(options));
+  }
+
+  private async openSessionInner(options: OpenSessionOptions): Promise<SessionRuntime> {
     this.ensureOpen();
     const current = this.getSessionForView(options.webviewId);
     const requestedId = options.sessionId ?? current?.id;
@@ -119,7 +124,7 @@ export class PythinkerRuntime {
     if (runtime !== undefined) {
       assertSessionWorkDir(runtime.session, options.workDir);
       await applySessionPermission(runtime.session, runtime.permissionMode);
-      await this.detachView(options.webviewId);
+      await this.detachViewInner(options.webviewId);
     } else {
       const seedMode = defaultPermissionMode(options.yoloMode);
       const session =
@@ -135,7 +140,7 @@ export class PythinkerRuntime {
       try {
         assertSessionWorkDir(session, options.workDir);
         const mode = await restorePermissionMode(session, seedMode);
-        await this.detachView(options.webviewId);
+        await this.detachViewInner(options.webviewId);
         runtime = this.wrapSession(session, mode);
       } catch (error) {
         await session.close().catch((closeError: unknown) => {
@@ -156,14 +161,24 @@ export class PythinkerRuntime {
     webviewId: string,
     session: Session,
     yoloModeSetting = false,
+  ): Promise<SessionRuntime> {
+    return this.serializeView(webviewId, () =>
+      this.attachResumedSessionInner(webviewId, session, yoloModeSetting),
+    );
+  }
+
+  private async attachResumedSessionInner(
+    webviewId: string,
+    session: Session,
+    yoloModeSetting: boolean,
   ): Promise<SessionRuntime> {
     const existing = this.sessions.get(session.id);
     if (existing !== undefined && this.sessionByView.get(webviewId) === session.id) {
       existing.subscribe(webviewId);
       await existing.announceStatus(webviewId);
       return existing;
     }
-    await this.detachView(webviewId);
+    await this.detachViewInner(webviewId);
     let runtime = existing ?? this.sessions.get(session.id);
     if (runtime === undefined) {
       try {
@@ -184,6 +199,10 @@ export class PythinkerRuntime {
   }
 
   async detachView(webviewId: string): Promise<void> {
+    return this.serializeView(webviewId, () => this.detachViewInner(webviewId));
+  }
+
+  private async detachViewInner(webviewId: string): Promise<void> {
     const id = this.sessionByView.get(webviewId);
     if (id === undefined) return;
     this.sessionByView.delete(webviewId);
@@ -196,6 +215,23 @@ export class PythinkerRuntime {
     }
   }
 
+  // A view attaches to at most one session, so opens/detaches for one view
+  // must never overlap: concurrent callers that both miss `this.sessions`
+  // would wrap the same SDK session twice and double every streamed event.
+  private serializeView<T>(webviewId: string, work: () => Promise<T>): Promise<T> {
+    const prev = this.viewChains.get(webviewId) ?? Promise.resolve();
+    const run = prev.then(work, work);
+    const next = run.then(
+      () => undefined,
+      () => undefined,
+    );
+    this.viewChains.set(webviewId, next);
+    void next.finally(() => {
+      if (this.viewChains.get(webviewId) === next) this.viewChains.delete(webviewId);
+    });
+    return run;
+  }
+
   async closeSession(id: string): Promise<void> {
     const runtime = this.sessions.get(id);
     if (runtime === undefined) {

apps/vscode/test/pythinker-runtime.test.ts

@@ -382,6 +382,91 @@ describe("Pythinker runtime (owns shared SDK sessions for Webviews)", () => {
     expect(boundary.handlerInstallations).toEqual({ approval: 1, question: 1 });
   });
 
+  it("does not double-wrap the SDK session when two opens race for it", async () => {
+    const sdk = createFakeHarness();
+    const broadcasts: { event: string; data: unknown; webviewId?: string }[] = [];
+    const runtime = new PythinkerRuntime({
+      version: "0.6.0",
+      harness: sdk.harness,
+      broadcast: (event, data, webviewId) => {
+        broadcasts.push({ event, data, webviewId });
+      },
+      captureBaseline: () => undefined,
+      log: () => undefined,
+    });
+    const boundary = sdk.addSession("saved-1", "/workspace");
+
+    const [first, second] = await Promise.all([
+      runtime.openSession(openOptions({ sessionId: "saved-1" })),
+      runtime.openSession(openOptions({ sessionId: "saved-1" })),
+    ]);
+
+    expect(second).toBe(first);
+    expect(boundary.subscriptionCount()).toBe(1);
+
+    boundary.emit({
+      type: "assistant.delta",
+      sessionId: "saved-1",
+      agentId: "main",
+      turnId: 1,
+      delta: "Hello",
+    });
+
+    const parts = broadcasts.filter(
+      ({ data }) => (data as { type?: string }).type === "ContentPart",
+    );
+    expect(parts).toHaveLength(1);
+  });
+
+  it("coalesces two concurrent new-session opens for one view onto one session", async () => {
+    const { runtime, sdk } = createRuntime();
+
+    const [first, second] = await Promise.all([
+      runtime.openSession(openOptions()),
+      runtime.openSession(openOptions()),
+    ]);
+
+    expect(second).toBe(first);
+    expect(sdk.createInputs).toHaveLength(1);
+    expect(first.subscribers).toEqual(["view-1"]);
+  });
+
+  it("does not double-wrap the SDK session when two attaches race for it", async () => {
+    const sdk = createFakeHarness();
+    const broadcasts: { event: string; data: unknown; webviewId?: string }[] = [];
+    const runtime = new PythinkerRuntime({
+      version: "0.6.0",
+      harness: sdk.harness,
+      broadcast: (event, data, webviewId) => {
+        broadcasts.push({ event, data, webviewId });
+      },
+      captureBaseline: () => undefined,
+      log: () => undefined,
+    });
+    const boundary = sdk.addSession("saved-1", "/workspace");
+
+    const [first, second] = await Promise.all([
+      runtime.attachResumedSession("view-1", boundary.session),
+      runtime.attachResumedSession("view-1", boundary.session),
+    ]);
+
+    expect(second).toBe(first);
+    expect(boundary.subscriptionCount()).toBe(1);
+
+    boundary.emit({
+      type: "assistant.delta",
+      sessionId: "saved-1",
+      agentId: "main",
+      turnId: 1,
+      delta: "Hello",
+    });
+
+    const parts = broadcasts.filter(
+      ({ data }) => (data as { type?: string }).type === "ContentPart",
+    );
+    expect(parts).toHaveLength(1);
+  });
+
   it("preserves the resumed session's model instead of reapplying the configured default", async () => {
     const { runtime, sdk } = createRuntime();
     const session = sdk.addSession("saved-1", "/workspace", { model: "old-model" });

docs/reference/server-api.md

@@ -177,6 +177,7 @@ Endpoints are grouped by resource below. A `:{action}` suffix in a path is the a
 | `GET /api/v1/sessions/{session_id}/tasks` | List background tasks |
 | `GET /api/v1/sessions/{session_id}/tasks/{task_id}` | Read a task (optional output preview) |
 | `POST /api/v1/sessions/{session_id}/tasks/{task_id}:cancel` | Cancel a task |
+| `POST /api/v1/sessions/{session_id}/tasks/{task_id}:detach` | Move a foreground task to the background |
 
 ### Skills, tools, and MCP
 

packages/agent-core-v2/docs/state-manifest.d.ts

@@ -1353,6 +1353,7 @@ export interface AgentStateSnapshot {
     readonly command: string;
     readonly pid: number;
     readonly exitCode: number | null;
+    readonly parentToolCallId?: string;
     readonly taskId: string;
     readonly description: string;
     readonly status: /* AgentTaskStatus — packages/agent-core-v2/src/agent/task/types.ts */ 'completed' | 'failed' | 'running' | 'timed_out' | 'killed' | 'lost';
@@ -1400,6 +1401,7 @@ export interface AgentStateSnapshot {
     readonly command: string;
     readonly pid: number;
     readonly exitCode: number | null;
+    readonly parentToolCallId?: string;
     readonly taskId: string;
     readonly description: string;
     readonly status: /* AgentTaskStatus — packages/agent-core-v2/src/agent/task/types.ts */ 'completed' | 'failed' | 'running' | 'timed_out' | 'killed' | 'lost';

packages/agent-core-v2/src/agent/loop/turnEvents.ts

@@ -69,6 +69,7 @@ export function turnPromptAttachments(
 
 export function isDisplayablePromptOrigin(origin: PromptOrigin): boolean {
   if (origin.kind === 'user') return true;
+  if (origin.kind === 'system_trigger' && origin.name === 'subagent') return true;
   return (
     (origin.kind === 'skill_activation' || origin.kind === 'plugin_command') &&
     origin.trigger === 'user-slash'

packages/agent-core-v2/src/agent/tools/agent/agentTool.ts

@@ -467,14 +467,14 @@ export class SubagentTool implements ISubagentTool {
 
       if (runInBackground) {
         return {
-          output: formatBackgroundAgentResult(taskId, handle, args.description, allowBackground),
+          output: formatBackgroundAgentResult(taskId, handle, args.description, allowBackground, false),
         };
       }
 
       const release = await this.tasks.waitForForegroundRelease(taskId);
       if (release === 'detached') {
         return {
-          output: formatBackgroundAgentResult(taskId, handle, args.description, allowBackground),
+          output: formatBackgroundAgentResult(taskId, handle, args.description, allowBackground, true),
         };
       }
       return await this.formatForegroundResult(taskId, handle, timeoutMs);
@@ -560,7 +560,11 @@ function formatBackgroundAgentResult(
   handle: SubagentHandle,
   description: string,
   allowBackground: boolean,
+  detachedByUser: boolean,
 ): string {
+  const nextStep = allowBackground
+    ? `next_step: The completion arrives automatically in a later turn — do NOT wait, poll, or call TaskOutput on it; continue with other work or hand back to the user. (If you have nothing to do until it finishes, run such tasks in the foreground next time.)`
+    : 'next_step: The completion arrives automatically in a later turn.';
   return [
     `task_id: ${taskId}`,
     'status: running',
@@ -570,9 +574,7 @@ function formatBackgroundAgentResult(
     '',
     `description: ${description}`,
     '',
-    allowBackground
-      ? `next_step: The completion arrives automatically in a later turn — do NOT wait, poll, or call TaskOutput on it; continue with other work or hand back to the user. (If you have nothing to do until it finishes, run such tasks in the foreground next time.)`
-      : 'next_step: The completion arrives automatically in a later turn.',
+    detachedByUser ? `note: The user moved this subagent to the background.\n${nextStep}` : nextStep,
     `resume_hint: To continue or recover this same subagent later, call Agent(resume="${handle.agentId}", prompt="..."). The parameter is agent_id ("${handle.agentId}"), NOT task_id ("${taskId}") or source_id from a later <notification>. Recovery cases: a later <notification type="task.lost" | "task.failed" | "task.killed"> for this subagent — its conversation history is preserved across session restarts and resume will pick it up.`,
   ].join('\n');
 }

packages/agent-core-v2/src/agent/tools/ask-user-question/askUserQuestionTool.ts

@@ -146,7 +146,7 @@ export class AskUserQuestionTool implements IAskUserQuestionTool {
         'next_step: Continue your current work; the answer will arrive automatically when the user responds.\n' +
         'next_step: Use TaskOutput with this task_id for a non-blocking status/answer snapshot.\n' +
         'next_step: Use TaskStop only if the question should be cancelled.\n' +
-        'human_shell_hint: The pending question is also visible in /tasks.',
+        'human_shell_hint: The pending question is also visible in the client UI.',
     };
   }
 

packages/agent-core-v2/src/agent/tools/os/bash/bash.md

@@ -13,11 +13,11 @@ The dedicated tools render in the per-tool permission UI and keep raw stdout out
 **Output:**
 The stdout and stderr will be combined and returned as a string. The output may be truncated if it is too long. If the command exits non-zero, the output ends with a `Command failed with exit code: N` line; a command killed by its timeout or interrupted by the user ends with its own message instead.
 
-If `run_in_background=true`, the command will be started as a background task and this tool will return a task ID instead of waiting for command completion. When doing that, you must provide a short `description`. Background commands default to a ${DEFAULT_BACKGROUND_TIMEOUT_S}s timeout and `timeout` is capped at ${MAX_BACKGROUND_TIMEOUT_S}s; set `disable_timeout=true` only when the task should run without a timeout. You will be automatically notified when the task completes. After starting one, default to returning control to the user instead of immediately waiting on it. Use `TaskOutput` only for a non-blocking status/output snapshot — do not wait on a task you just launched, since its completion arrives automatically. Use `TaskStop` only if the task must be cancelled. If a human user wants to inspect background tasks themselves, point them to the `/tasks` command, which opens an interactive panel; it has no subcommands.
+If `run_in_background=true`, the command will be started as a background task and this tool will return a task ID instead of waiting for command completion. When doing that, you must provide a short `description`. Background commands default to a ${DEFAULT_BACKGROUND_TIMEOUT_S}s timeout and `timeout` is capped at ${MAX_BACKGROUND_TIMEOUT_S}s; set `disable_timeout=true` only when the task should run without a timeout. You will be automatically notified when the task completes. After starting one, default to returning control to the user instead of immediately waiting on it. Use `TaskOutput` only for a non-blocking status/output snapshot — do not wait on a task you just launched, since its completion arrives automatically. Use `TaskStop` only if the task must be cancelled. If a human user wants to inspect background tasks themselves, point them to the background-task panel.
 
 **Guidelines for safety and security:**
 - Each shell tool call will be executed in a fresh shell environment. The shell variables, current working directory changes, and the shell history is not preserved between calls. To run a command in a particular directory, pass the `cwd` argument (or use absolute paths) rather than relying on a `cd` from an earlier call.
-- The tool call will return after the command is finished. You shall not use this tool to execute an interactive command or a command that may run forever. For possibly long-running foreground commands, set the `timeout` argument in seconds. Foreground commands default to ${DEFAULT_TIMEOUT_S}s and allow up to ${MAX_TIMEOUT_S}s. When a foreground command hits its timeout it is moved to the background instead of being killed, and you will be automatically notified when it completes.
+- The tool call will return after the command is finished. You shall not use this tool to execute an interactive command or a command that may run forever. For possibly long-running foreground commands, set the `timeout` argument in seconds. Foreground commands default to ${DEFAULT_TIMEOUT_S}s and allow up to ${MAX_TIMEOUT_S}s. When a foreground command hits its timeout it is moved to the background instead of being killed, and you will be automatically notified when it completes. The user can also move a running foreground command to the background at any time.
 - Avoid using `..` to access files or directories outside of the working directory.
 - Avoid modifying files outside of the working directory unless explicitly instructed to do so.
 - Never run commands that require superuser privileges unless explicitly instructed to do so.