[BUG] Permission preview flickers / scroll snaps back when reviewing long Write or Edit tool-call content

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?

Actual behavior

1. The preview pane flickers and the scroll position snaps back down.
2. The effect is worst when trying to reach the top of long content — the user cannot stabilize the view to read the beginning of the file.

Impact

• The user cannot verify what Claude is about to write before approving.
• The only current workaround is to ask Claude to paste the full content into the chat as a code block first (where scrolling works normally), then approve the actual tool call. This

forces an extra round-trip per write and incurs unnecessary token cost to work around a UI limitation.

What Should Happen?

The preview pane should support smooth, persistent scrolling in both directions so the entire content can be reviewed before clicking Yes/No.

Error Messages/Logs

Steps to Reproduce

1. Ask Claude to perform a Write or Edit that produces a large block of content (e.g. a new file or edit with 100+ lines).
2. When the permission prompt appears, try to scroll the preview pane upward to read the top of the proposed content.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.145 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Sample :

https://github.com/user-attachments/assets/99f059a8-237e-4806-be20-a1688efcef49

Suggested Fix:

1. Make the preview pane fully scrollable without focus stealing or layout reflow.
2. Optionally add an "Expand / View in editor" button for very long diffs so the user can review in a stable view.