[BUG] Browser pane detached to separate window is slow/visually corrupted — regression in 1.49585.0

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?

Detaching the in-app Browser pane into a separate OS window causes visible frame corruption (pixelated/static overlay across the whole page) and consistently slow, choppy frame delivery. The docked pane (side panel) renders correctly.

What Should Happen?

The detached window should render smoothly and correctly, the same as the docked pane or a normal browser tab on the same page.

Error Messages/Logs

None found. Checked dmesg for GPU/DRM errors, journalctl for claude-desktop crash/hang/timeout entries, and the Crashpad directory for dump files — all clean. The bug shows up as visual corruption, not a logged error or crash.

Steps to Reproduce

1- Open the Browser pane docked in the side panel and navigate to any local or web page.
2- Pop it out into a separate window.
3- Observe pixelated/static-like corruption over the page content and slow, choppy frame updates when scrolling or when the page has motion (e.g. autoplay video).

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.46388.2

Claude Code Version

2.1.260

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

Ruled out local causes before concluding this is a regression: cleared Claude Desktop's cache (Cache, Code Cache, GPUCache — ~480MB) and did a full device reboot, neither fixed the detached-window issue (though the cache clear did fix a separate, unrelated slowdown in the docked pane caused by a prior crash + force-kill). A plain Chrome tab on the same localhost URL renders smoothly, confirming it isn't the page/dev-server content. Downgrading to 1.46388.2 and pinning with apt-mark hold fully resolved the detached-window corruption/lag, confirming the regression was introduced somewhere between 1.46388.2 and 1.49585.0. Screenshot of the corruption available on request.