Codex app cannot create a new task from a devbox after create_thread tool migration #39978

Codex App version

ChatGPT Nightly, restarted and updated immediately before the second reproduction. The exact About-dialog version is not available from inside the remote task.

Remote Codex CLI: 0.150.0-alpha.3 on the alpha track.

Subscription

OpenAI employee workspace.

Platform

macOS ChatGPT desktop app connected to a remote Linux devbox.

What issue are you seeing?

A Codex task running on a remote devbox cannot create another user-visible task. Project discovery succeeds, and other Codex app task tools such as list_projects and set_thread_title work, but create_thread fails before creating anything with this exact error:

This app tool is no longer available through dynamic tools. Use the codex_app MCP server. If that server is unavailable on this host, task delegation is unavailable.

No task or worktree is created.

Steps to reproduce

1. Open a repository task in the ChatGPT desktop app using a remote Linux devbox.
2. Ask Codex to start a separate task for a bounded investigation.
3. Codex calls list_projects successfully and resolves the remote Git repository.
4. Codex calls create_thread with a project target and worktree environment.
5. The call returns the migration error above.
6. Fully quit and restart the desktop app, update it, reopen the remote task, refresh the project inventory, and retry.
7. The same error occurs.

Session ID: 01a0209f-a999-7dc3-bcae-eb0fdae4efd9

Expected behavior

create_thread should create the requested user-visible task on the selected remote project and return a thread ID or queued client thread ID.

Additional information

• Reproduced multiple times before and after restarting/updating the desktop app.
• list_projects and set_thread_title continue to work in the same task.
• The devbox Codex CLI is already on a current alpha build, so this appears to be a desktop-app/tool-routing version mismatch rather than an outdated devbox CLI.
• I searched openai/codex issues for the exact error, codex_app MCP server, create_thread, devbox, and task delegation before filing and found no matching report.
• No logs are attached because this task contains internal production investigation context.