Codex mobile lists subagent threads as workdir projects

Title: Codex mobile lists subagent threads as workdir <hash> projects and floods the project list

Summary

When subagents are spawned from Codex Desktop/App, Codex mobile shows many top-level folder entries named workdir <8-char hash> for the same host. These entries do not appear as normal projects in the desktop app project list, but they appear on mobile and can flood the mobile UI until it becomes hard to use.

Environment

• Host OS: macOS
• Codex Desktop: 26.616.81150, build 4306
• Local codex --version: codex-cli 0.140.0
• Current desktop/app session state reported CLI version: 0.142.0
• Mobile app: Codex iOS, version not checked
• Feature involved: subagents / multi-agent thread spawning

Steps To Reproduce

1. Open Codex Desktop/App on macOS.
2. Start a normal project thread.
3. Ask Codex to use multiple subagents for parallel work or review.
4. Let the subagent threads complete or remain open.
5. Open Codex mobile and connect to the same desktop host.
6. View the mobile project/thread list for that host.

Expected Behavior

Subagent threads should either:

• stay hidden from the top-level mobile project list,
• be grouped under the parent thread, or
• be clearly labeled as subagent threads rather than shown as project folders.

Actual Behavior

Codex mobile shows many top-level folder entries named like workdir 12283408, workdir 37c83c7c, etc. Some expanded entries show subagent prompt preview text. Desktop does not show these as normal saved projects, so there is no obvious desktop-side way to clean them up from the same UI.

In one local state, there were 156 unarchived rows with thread_source='subagent'. These corresponded to source values containing subagent.thread_spawn. After deleting those subagent threads locally, the mobile clutter disappeared from the normal thread/project list.

Impact

The mobile app becomes difficult or impossible to use after several desktop subagent workflows because the list is dominated by generated workdir entries.

Diagnostics

• list_projects showed only real saved projects, not the workdir <hash> entries.
• The active local state database had many rows where thread_source='subagent'.
• The issue appears to be a mobile/remote host listing problem: subagent worker threads are being exposed as top-level mobile project/thread entries, while desktop hides or presents them differently.

Suggested Fix

Hide subagent worker threads from the mobile top-level project list, or group them under their parent thread using thread_spawn_edges. If they must be visible, label them as subagents and provide a bulk cleanup/archive action.