[BUG] Cowork left sidebar completely missing — no Settings, navigation, or Feedback buttons visible

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

The entire left sidebar in Cowork is missing/collapsed and cannot be reopened. This sidebar contains critical UI elements including Settings, navigation between modes (Chat/Code/Cowork), and the Feedback button — none of which are accessible.
The X button at the top left appears to be stuck together with the collapsed sidebar and is also non-functional.
As a result, it is impossible to:

Access Settings
Navigate between app modes
Use the Feedback button to report the issue from within the app

Restarting the application does not resolve the issue.

<img width="1462" height="1010" alt="Image" src="https://github.com/user-attachments/assets/21499650-a7ff-4ac1-baef-e03040c36690" />

What Should Happen?

The left sidebar should be fully visible and functional, displaying all navigation options including Settings, mode switching (Chat / Code / Cowork), and the Feedback button. The X button should work independently and not be tied to the sidebar state.

Error Messages/Logs

Steps to Reproduce

Steps to Reproduce:

Open Claude Desktop app
Navigate to Cowork mode
Observe that the left sidebar is collapsed and cannot be expanded
Attempt to click the X button — it is unresponsive
No Settings, navigation, or Feedback button are accessible

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

cant find, part of the problem

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_