File changes Undo button does NOT work

What version of the IDE extension are you using?

0.4.76

What subscription do you have?

Plus

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?

<img width="420" height="339" alt="Image" src="https://github.com/user-attachments/assets/272fd33a-a221-4aed-92a0-3a06f1850d43" />
The codex file changes button simply does not work. It does not do anything, at all, whatsoever.

Codex haphazardly proceeds to make changes to the code after simply being asked a question, without any implication of call to action. This has been an issue ever since Chat mode has been removed.

What steps can reproduce the bug?

1. Ask codex to make some changes to the code across multiple files
2. Click Undo button in the file changes block

What is the expected behavior?

The undo button works (or Chat mode is brought back)

Additional information

Codex.log