VS Code extension does not show subagent activity and loses conversation state

What version of the IDE extension are you using?

Version: 1.128.0 (user setup) Commit: fc3def6774c76082adf699d366f31a557ce5573f Date: 2026-07-07T15:14:24-07:00 Electron: 42.5.0 ElectronBuildId: 14525058 Chromium: 148.0.7778.271 Node.js: 24.17.0 V8: 14.8.178.33-electron.0 OS: Windows_NT x64 10.0.26200

What subscription do you have?

200 usd

Which IDE are you using?

vs code

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

Codex subagents execute and complete successfully in the backend, but the VS Code extension does not
display their work in real time.

Newly spawned subagents may be missing from the subagent dropdown. If an entry appears, clicking it may
do nothing. After reloading the VS Code window, previously missing subagents sometimes become visible.

on CLI codex After assistant responses, the extension also displays:

Stop hook (failed)
error: hook returned stop hook json output

The Stop-hook error appears to be a secondary symptom rather than the cause. The extension logs
"Conversation state not found" before "hook/started" for the affected subagent conversation.

The backend continues working correctly. The affected subagent rollout records contain "status: success"
and "task_complete".

What steps can reproduce the bug?

1. Open the Codex extension in VS Code on Windows.
2. Start a Codex conversation using gpt 5.6 sol xhigh
3. Send a prompt that causes Codex to spawn a subagent, for example:

Use one subagent to perform a read-only inspection and wait for it to complete.

1. While the subagent is running, open the subagent dropdown.
2. Observe that the new subagent is missing, or select it and observe that nothing opens.
3. Wait for the subagent and parent response to finish.

1. Reload the VS Code window.
2. Open the subagent dropdown again.
3. Observe that previously missing subagents may now appear.

The issue reproduces across multiple successful subagent runs.

What is the expected behavior?

Newly spawned subagents should appear immediately in the VS Code extension.

Their active work and messages should stream in real time. Selecting a subagent should open its
conversation while it is running and after it completes.

Hook events should remain associated with the correct conversation. A successful subagent task and a
Stop hook that exits successfully should not produce a misleading failure message.

### Additional information

Environment:

OS: Microsoft Windows NT 10.0.26200.0 x64
IDE: VS Code 1.128.0
Codex IDE extension: 26.707.41301
Codex CLI: 0.144.1
Subscription: Pro
Multi-agent enabled: true
Maximum threads: 4
Maximum depth: 2

Relevant sanitized log messages:

[IpcClient] Received broadcast but no handler is configured method=thread-stream-state-changed

Conversation state not found conversationId=<redacted>

Received hook/started for unknown conversation conversationId=<redacted>

Received hook/completed for unknown conversation conversationId=<redacted>

Observed counts in one affected extension-host log:

• thread-stream-state-changed broadcasts without a handler: 4167
• Conversation state not found: 152
• hook/started for unknown conversation: 9
• hook/completed for unknown conversation: 9

The affected subagents still recorded:

status: success
task_complete

An Engram plugin Stop hook is installed. The Stop script suppresses command output and exits with code

1. The missing conversation-state error occurs before the Stop hook starts, so the hook does not appear

to be the initial cause.

Reloading the VS Code window can make older subagents visible, but it does not prevent the issue from
recurring.

Possibly related issues:

https://github.com/openai/codex/issues/13343
https://github.com/openai/codex/issues/20208
https://github.com/openai/codex/issues/24475

Additional information

_No response_