[BUG] Pull request created against wrong branch

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 Claude Code Desktop App on MacOS
Claude 1.1.8629 (befdfc) 2026-03-24T22:13:01.000Z

After claude code makes code changes against a selected origin branch (main-claude) a PR is automatically created against a different origin branch (main).

What Should Happen?

The generated PR should be compared against the selected origin branch "main-claude"

Error Messages/Logs

Steps to Reproduce

1. Branch main to main-claude in Github
2. Request to plan code changes selecting Repository, Branch "main-claude." Plan mode, Opus 4.6.
3. Approve the plan, code changes are executed.
4. PR is automatically created.
5. View PR
6. PR for the claude-generated branch is against origin\main and not origin\main-claude.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.1.8629 (befdfc) 2026-03-24T22:13:01.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_