[BUG] Incorrect Color-Highlighted Diffs in code changes

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?

In analyzing a suggested code change I noticed that the color diffs for a particular code change were incorrectly highlighting the change. Namely:

• The text for example in records was not highlighted as being removed.
• The text "metadata" was highlighted as being new when it wasn't
• The word example was replaced by element but neither were highlighted.

<img width="1652" height="895" alt="Image" src="https://github.com/user-attachments/assets/9ebf7528-59bd-4a57-98ac-c42b471c333f" />

What Should Happen?

I would expect the highlighting to highlight all changed, added, and deleted text correctly.

Error Messages/Logs

Steps to Reproduce

Sorry, I'm not sure I have a way to help reproduce this.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

4.6

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_