find-regression-risk

Detects potential regression risks in a PR by cross-referencing removed lines against lines added by recent labeled bug-fix PRs.

How It Works

Purely mechanical — no AI/LLM. Five-step algorithm:

1. PR diff — collects lines REMOVED by the PR under review.
2. Git history — git log --follow --since=6mo finds recent PRs that touched the same files.
3. Label filter — keeps PRs (or their linked issues) labeled i/regression, t/bug, p/0, or p/1.
4. Fix diff — fetches each fix PR's diff and collects lines it ADDED to the same file.
5. Compare — whitespace-insensitive string equality:
   • 🔴 REVERT — removed line matches a line a fix PR added (highest risk).
   • 🟡 OVERLAP — same file modified, but no exact line revert.
   • 🟢 CLEAN — no bug-fix PRs touch the same files.

Standalone Invocation