[Desktop app, Windows] Browser pane rendered twice: in its split and over the transcript

Summary

In the Claude desktop app (Code tab) on Windows, the built-in Browser pane is drawn twice: once in its own split on the right, and a second copy painted over the transcript/chat area on the left. Both copies show the same page. The duplicate stays even after the agent closes the pane.

Environment

• Claude desktop app 2.9939.2.0, Microsoft Store (MSIX) build, stock signed binaries
• Windows 11 Pro, build 10.0.26200
• Session: Claude Code tab, single session in the main window, no split view, no pop-out
• Language/locale: Hebrew UI content in the transcript (RTL text), app itself in default layout

Steps to reproduce

1. Open a Code session in the desktop app.
2. Have the agent open the Browser pane (navigate / preview_start from the Claude_Browser tools) with any URL, e.g. https://unified.cloudways.com/login.
3. Look at the window.

What happens

The page renders in the right split as expected, and an identical second copy covers the transcript area on the left (the chat messages behind it are hidden, only the top of the last message remains visible). Screenshot available on request.

What was tried

• Agent closed the last tab (tabs_close), which closes the pane, then reopened with preview_start: still doubled.
• Agent closed the pane again: the user still saw both copies afterwards.
• At the same moment, get_layout for the session reported views: [] / "session isn't open in any window", and get_window_layout listed a different session id as the focused pane, while the user was clearly looking at this session. Possibly the layout state got out of sync and the pane was attached to the wrong view.

Expected

One Browser pane, in its split only, and the transcript stays visible.

_Filed by the user's Claude Code session on their behalf._