[BUG] Claude Desktop (macOS): Empty overlay element appears in main view when moving mouse from sidebar

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?

When the sidebar (chat history) is open and the mouse cursor is moved from the sidebar into the main content area, a narrow empty overlay element appears between the sidebar and the main view. This element is invisible/blank but covers the underlying content of the main view, making it inaccessible.

What Should Happen?

The main content area remains fully accessible and unobstructed.

Error Messages/Logs

Steps to Reproduce

1. Open Claude Desktop with the sidebar visible
2. Move the mouse cursor from inside the sidebar into the main content area

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

N/A

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

• Moving the mouse into the main area from outside the app window does not trigger the issue — only the transition from sidebar to main view.
• Related to issue #50297 (sidebar jitter/ghosting), but distinct: the overlay is persistent and does not resolve without a restart.