[BUG] diff feature used to show changes made, now it shows a diff of the entire branch compared to master.

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?

I used to be able to see only the diffs of what Claude Code was doing on changes that were not pushed. Now it seems to be hard coded to show the diffs between the entire branch you're on and master, which is a much larger set of files than what the current session might be changing.

What Should Happen?

We need to be able to see more specific diffs than just comparing to master, such as to the same branch at origin.

Error Messages/Logs

Steps to Reproduce

1. Check out an existing feature branch that has its own set of code changes.
2. Start making additional changes to the feature branch using Claude Code.
3. Open the diff tool, and you can only see all the differences comparing the branch to master.
4. Although you can click through specific commits, there does not appear to be any way to change the source branch you are diffing against and only show diffs of unstaged changes.
5. You likely only care about the new differences that you've made compared to the same feature branch on origin.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.13576.4 (414f85) 2026-06-18T02:11:10.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_