codex

Step 0: Detect platform and base branch

First, detect the git hosting platform from the remote URL:

git remote get-url origin 2>/dev/null

• If the URL contains "github.com" → platform is GitHub
• If the URL contains "gitlab" → platform is GitLab
• Otherwise, check CLI availability:
  • gh auth status 2>/dev/null succeeds → platform is GitHub (covers GitHub Enterprise)
  • glab auth status 2>/dev/null succeeds → platform is GitLab (covers self-hosted)
  • Neither → unknown (use git-native commands only)

Determine which branch this PR/MR targets, or the repo's default branch if no PR/MR exists. Use the result as "the base branch" in all subsequent steps.