[BUG] Unable to swap base 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?

When using the Claude Code branch/PR selection UI on a branch that tracks a remote branch (not main), the UI defaults to comparing against main. Attempting to change the base branch to the correct remote tracking branch displays "Unable to load branches" and no branches are listed. I cannot use this app right now because I do not want to push commits against main.

What Should Happen?

The base branch should default to the branch's upstream tracking ref (in this case origin/cwyrick/jira-123), not main.
At minimum, the branch selector dropdown should load and display all available remote branches so the user can manually change the base.
Actual behavior:

Base branch defaults to main regardless of the upstream tracking configuration.
Clicking to change the base branch shows "Unable to load branches" — the dropdown fails to populate entirely.

Error Messages/Logs

Steps to Reproduce

Open Claude Code on a feature branch that has an existing PR on the remote repo.
Open the branch/PR selection UI in claude code.
Observe the base branch defaults to main.
Attempt to change the base branch — "Unable to load branches" is displayed.

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.86 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

When using the Claude Code branch/PR selection UI on a branch that tracks a remote branch (not main), the UI defaults to comparing against main. Attempting to change the base branch to the correct remote tracking branch displays "Unable to load branches" and no branches are listed.