I built culprit: A CLI that automatically finds the exact commit that caused a bug
If you have ever spent hours doing git blame gymnastics to figure out exactly when a line of code was silently broken, I built this to automate that exact workflow.
Here is what it does under the hood:
- Bugfix RCA: It automatically finds the commit that introduced the bug by analyzing the lines your PR removes or changes. It ranks the suspect commits and tracks the "line-evolution timeline".
- Blast Radius Mapping: For new features, it maps out the impact by detecting who imports the changed modules, identifying test coverage gaps, and highlighting high-risk shared files.
- Visual HTML Reports: You can run
rca --html report.htmlto generate a self-contained, offline-friendly visual timeline showing the code from creation, to the breaking commit (highlighted in red), to your fix (in green). - AI Narrative: It includes an optional reasoning layer (using Claude API or the Claude Code skill) that writes a plain-text narrative explaining why the original commit broke things.
- Language Agnostic: The core Git timeline tracking works on any repository, and the import/blast-radius parser supports Python, JS/TS, Go, Rust, Java, C++, and more.
It runs completely locally, never modifies your code, and natively supports GitHub, GitLab, Bitbucket, and Gitea.
You can try it out via pip or pipx:pipx install culprit
Check out the repo here: https://github.com/noordeen123/culprit
I would love to hear your feedback, especially if you have ideas for improving the RCA engine or the visual reports. Happy debugging!
u/RKO_NOORDEEN — 8 days ago