Codex App: main-thread subagent list regressed - missing agents and broken expand/collapse control

What version of the Codex App are you using (From “About Codex” dialog)?

26.415.20818

What subscription do you have?

Pro

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

In the main thread, the subagent list UI is sometimes inconsistent.

I have seen at least three failure modes:

1. After multiple subagents are spawned, the expanded list omits one of the agents that was actually created.
2. Sometimes the expand/collapse arrow is missing entirely.
3. Sometimes the arrow is visible, but after clicking it once, the list expands and then immediately collapses again. After that, the control appears stuck and is no longer interactable.

This looks like a UI/state-sync regression rather than an agent execution problem.

This is a regression. I can confirm the app behaved correctly a few versions ago, and this issue only started appearing in more recent versions.

The expanded dropdown list is incomplete:
<img width="598" height="290" alt="Image" src="https://github.com/user-attachments/assets/6066c387-93f6-489e-9eed-4dd2a5429900" />

<img width="495" height="344" alt="Image" src="https://github.com/user-attachments/assets/f1d8bdbf-fae0-421d-8278-7694b30a453f" />

After switching away and back, the dropdown toggle disappeared completely, leaving no way to expand the list:
<img width="787" height="56" alt="Image" src="https://github.com/user-attachments/assets/a4764d43-86ae-4828-9213-62fd8257ee5f" />

What steps can reproduce the bug?

1. Open Codex App on Windows.
2. In a main thread, trigger work that spawns multiple subagents.
3. Try to expand the subagent section.
4. Observe one of the following intermittent failures:

• one created agent is missing from the expanded list
• the expand/collapse arrow is missing
• clicking the arrow expands the list briefly, then it immediately collapses and becomes non-interactive

1. After switching to another thread, working there for a while, and then returning to the original main thread, the subagent dropdown sometimes disappears entirely, leaving no expand arrow to click or interact with.

What is the expected behavior?

The main thread should always show the full list of spawned subagents.
If the subagent section is expandable, the expand/collapse control should remain visible, stable, and interactable.
Clicking the control should not immediately revert the expanded state unless the user collapses it.

Additional information

_No response_