[BUG] Sidebar resize handle hover causes chat content clipping (macOS, v1.3109.0)

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 hovering over the right edge of the sidebar (the resize handle), the chat content area is visually clipped — content on the left side of the chat panel is cut off. The clipping persists as long as the cursor is near the resize handle. Closing the sidebar entirely removes the issue.

What Should Happen?

No visual change should occur when hovering over the sidebar resize handle.
Chat content should remain fully visible at all times.

Error Messages/Logs

Steps to Reproduce

1. Open Claude for Mac with sidebar visible
2. Hover cursor over the right edge of the sidebar (resize handle)
3. Chat content clips immediately — no click needed

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Before the new GUI

Claude Code Version

Claude for Mac 1.3109.0 (35cbf6)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

<img width="1590" height="962" alt="Image" src="https://github.com/user-attachments/assets/9c394230-6e32-4343-81a1-865561070c6d" />