[BUG] UI flickering in VS Code terminal during tool usage and general operation

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?

Experiencing visual flickering when using Claude Code in VS Code's integrated terminal. The terminal output flickers/jumps intermittently, creating a jarring visual experience. This happens both during tool execution and randomly during general operation.

What Should Happen?

Terminal output should be stable without visual flickering or artifacts. Text should render smoothly without jumping or flashing.

Error Messages/Logs

No error messages - this is a visual rendering issue.

Steps to Reproduce

1. Open VS Code
2. Open the integrated terminal
3. Run claude to start Claude Code
4. Use Claude Code normally - interact with it, ask questions, let it use tools
5. Observe flickering/visual artifacts in the terminal output, especially during:

• Tool execution (file reads, edits, bash commands)
• Random moments during operation

Claude Model

Opus

Is this a regression?

I don't know

Claude Code Version

2.1.11 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

See attached video demonstrating the flickering behavior.

https://github.com/user-attachments/assets/3a6b3330-9c23-4cae-b478-53a1fc11aea4