[BUG] /ultrareview fails "Could not find merge-base with main" despite local main branch existing with valid merge-base

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code (2.1.111)

What's Wrong?

/ultrareview (no args) fails with:

Could not find merge-base with main. Make sure you're in a git repo with a main branch.

despite:

• Being in a valid git repo
• Local main branch existing
• git merge-base master main resolving successfully to a valid commit SHA

The repo has no remote configured. I suspect /ultrareview is looking for origin/main (remote tracking) instead of local main, but the error message says "main" which is misleading.

What Should Happen?

Either:

1. /ultrareview should work with local main branch when no remote is configured, OR
2. The error message should clarify "Could not find origin/main — a GitHub remote is required"

Steps to Reproduce

mkdir /tmp/repro && cd /tmp/repro
git init
echo "a" > file.txt && git add . && git commit -m "init"
git branch main
echo "b" > file.txt && git commit -am "change"
# Now on master (default), main exists, merge-base resolves
git merge-base master main   # works, returns init commit SHA
/ultrareview                 # fails with "Could not find merge-base with main"

Claude Model

Opus 4.7

Claude Code Version

2.1.111

Platform

Anthropic API

Operating System

Linux (Debian 14)

Terminal/Shell

bash