VS Code plugin no longer shows diff per file module

What version of the IDE extension are you using?

Version: 1.118.1 (Universal)

What subscription do you have?

Plus

Which IDE are you using?

VS Code

What platform is your computer?

Darwin 25.4.0 arm64 arm

What issue are you seeing?

VS Code plugin used to show a diff per file module in earlier versions that was super helpful to quickly review the model's work.

It has disappeared from the VS code plugin chat window (though it still shows up if I initiated the change from the Codex app, weird.)

Also it has stopped showing the very useful undo button in the IDE.

Attached images of now and before.

Now:
<img width="879" height="480" alt="Image" src="https://github.com/user-attachments/assets/68d47d18-d13e-4203-97b8-6b7072290254" />

Before:
<img width="853" height="268" alt="Image" src="https://github.com/user-attachments/assets/f5de680a-c668-4624-bc8b-ba05533617a5" />

What steps can reproduce the bug?

Try initiating a change in the vscode plugin.

Then try initiating a change from the Codex app.

The former will not show diff per file module, the latter will.
I have tested this over dozens of messages.

What is the expected behavior?

_No response_

Additional information

_No response_