[BUG] CLAUDE_CODE_NO_FLICKER=1 produces weird rendering artifacts with zellij

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?

Zellij version: 0.44.0
Claude Code version: 2.1.89
Terminal: Kitty on macOS

Issue: When in full-screen mode (CLAUDE_CODE_NO_FLICKER=1), pressing Fn+Up/Fn+Down or using the mouse wheel to scroll produces rendering artifacts (see video).

Legacy scrollback mode renders correctly.

https://github.com/user-attachments/assets/79dd166b-e5ec-4ada-b13c-8eee9d70fbe0

What Should Happen?

The rendering should be normal.

Error Messages/Logs

Steps to Reproduce

1. Open claude code under a zellij session CLAUDE_CODE_NO_FLICKER=1 claude.
2. Try to scroll to see the rendering issue.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.89

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

_No response_