[BUG] Vertical screen tearing/corruption

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?

I'm seeing significant vertical screen tearing during Claude Code usage. This just started Mon June 8th, and was fine while working Fri June 5th. I've tried CLAUDE_CODE_FORCE_SYNC_OUTPUT=1, I've tried setting prefersReducedMotion. I do have a custom statusline script, I've tried removing all emojis from that, I've even tried changing that to echo '', to have no status line. I've tried all sorts of stuff, nothing works.

This is on Debian 13 KDE Plasma using Konsole. Fully updated, tried rebooting, still happens as I use CC over time. See the screenshot.

<img width="3430" height="1238" alt="Image" src="https://github.com/user-attachments/assets/a655453d-8836-4ce7-b16b-22238330fbf7" />

What Should Happen?

There should not be this wild tearing, that ends up making it virtually unusable.

Error Messages/Logs

I worked with my agent and we found some debug ENV vars, and it found some things pointing to issues in the rendering pipeline.

Here is the findings my agent came up with FINDINGS-renderer-tearing.md
And here is the raw log frames.log

Steps to Reproduce

Startup a new claude session in Konsole. Interact with it, and over time as the scrollback buffer gets larger, there starts to get some issues with the input line, and then eventually as output comes back and is scrolling up, things get corrupted.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.165

Claude Code Version

2.1.169

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information