codex_app thread tools missing after desktop update to 26.903.8094.0 / codex-cli 0.153.4 (regression of #37075/#30233) #44170

Summary

After the Codex desktop app updated to package OpenAI.Codex_26.903.8094.0 (bundled codex-cli 0.153.4), agent conversations on a custom (non-OpenAI) Responses provider only receive automation_update from the expected 11 codex_app thread tools. A previously verified working state (2026-09-06, codex-cli 0.153.1: 11/11 present, create_thread and list_threads called successfully) regressed after this update.

Environment

• OS: Windows
• App package: OpenAI.Codex_26.903.8094.0_x64__2p2nqsd0c76g0
• codex-cli: 0.153.4
• Provider: custom local Responses endpoint
• Related: Codex Desktop omits codex_app project/thread tools with a custom Responses provider #37075 (closed/completed 2026-08-26), Codex app thread-management tools not exposed despite thread creation being available #30233, Codex Desktop sometimes does not inject configured project MCP tools into a thread #24168, Codex App does not import plugin-bundled remote OAuth MCP server tools after codex mcp login until full app restart; new conversation insufficient; codex exec works #30716

Repro

1. Update the desktop app to the version above.
2. Start a new conversation (projectless).
3. Inspect the agent's available function list against the expected 11 codex_app tools.

Result: only automation_update is present. Missing: create_thread, fork_thread, handoff_thread, list_threads, read_thread, send_message_to_thread, set_thread_archived, set_thread_pinned, set_thread_title, wait_threads.

Evidence

1. The codex app-server process is launched with an inline MCP config whose cwd points inside the signed package:

   C:\Program Files\WindowsApps\OpenAI.Codex_26.903.8094.0_x64__2p2nqsd0c76g0\app\resources\plugins\openai-bundled\plugins\codex-app-tools

   and whose tools map contains only five entries: automation_update, create_thread, send_message_to_thread, fork_thread, handoff_thread.

2. The internal desktop-mcp.json at that package path confirms only those five tools are listed.

3. A plugin cache copy at ~/.codex/plugins/cache/openai-bundled/codex-app-tools/0.1.3/desktop-mcp.json lists all 11 tools, but the server is launched from the package path, so the cache copy is bypassed.

4. App logs show the codex_app MCP server status as ready for the affected thread, so the server starts; the tool set exposed to the agent is still incomplete.

Expected behavior

All 11 codex_app thread tools should be available to agent conversations regardless of provider or app build, consistent with the fix verified for #37075 on codex-cli 0.153.1. If the six list_threads / read_thread / wait_threads / set_thread_* tools were intentionally removed or moved in this build, please document the replacement mechanism.

Suggested fix direction

• Ensure the app-server launches codex_app MCP from a location that honors the plugin's full tool manifest (or the internal manifest lists all 11 tools), and
• Re-verify tool injection on custom Responses providers (regression check: 11/11 app tools present).