### Preflight Checklist - [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) 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? preview-pane rendering bug <img width="707" height="832" alt="Image" src="https://github.com/user-attachments/assets/3a6186ad-7dc0-4fb7-9d25-4ddc079719c3

[BUG] preview-pane rendering bug

Status Fixed / completed

Maintainer reply None cached

Activity 0 comments · opened Jul 30, 2026 · closed Jul 30, 2026

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?

preview-pane rendering bug

What Should Happen?

The preview pane should render a single instance of the page at http://localhost:4173. Instead it intermittently renders two full, independently-interactive copies of the app side-by-side (or overlapping/ghosted) within the same tab — each with its own working buttons. This happens even though the actual page's DOM has exactly one <body>, one <main>, one <h1>, verified directly via script injection — so the duplication originates in the preview pane itself, not in the page being previewed.

Error Messages/Logs

Steps to Reproduce

In Claude Code Desktop, start a local dev server and open it in the preview pane (e.g. npm run dev for a Next.js app, then open the preview at http://localhost:4173).
Work in the session for a while, navigating the preview pane, resizing it, and/or letting the dev server restart at least once (e.g. after stopping and restarting the background process running it).
At some point, reopen or refresh the preview tab inside Claude Code Desktop.
Observe: the preview pane renders two full, independently-interactive copies of the page side-by-side in the same tab — each with its own working buttons — instead of one.
Note: this is intermittent — it did not reproduce every time, and closing/reopening the preview tab sometimes cleared it temporarily before it reappeared. Verified via direct DOM inspection (document.querySelectorAll for key elements) that the actual page served by the dev server contains exactly one instance of everything — so the duplication is introduced by the preview pane itself, not the page.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Version 1.24012.9 (03c61d)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information