[BUG] Black floating rectangle artifact follows cursor when Claude desktop app is open (macOS)

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?

A thin black rectangular artifact appears on screen and follows the cursor.
It disappears when the cursor moves slightly. Only occurs when the Claude desktop app is open.

What Should Happen?

No visual artifacts on screen.

Error Messages/Logs

Steps to Reproduce

1. Open the Claude desktop app
2. Move the cursor around the screen
3. Observe a thin black floating rectangle artifact that tracks the cursor

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Version 1.11847.5 (9692f0)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

The issue does not occur when Claude is closed, confirming it is Claude-specific.