Problem I kept hitting: ask the agent for a 15-line fix, get a 500-line renovation that still compiles and passes tests.

Boffin is a small control layer for AI coding agents. Before an edit, it feeds the agent only the architectural constraints for the file it is about to touch, then makes it verify the result. Not another static AGENTS.md for the whole repo.

On DuckDB, a guided refactor landed at +17 / -17 lines with 2,104 assertions passing. Same shape of cases also on FastAPI and LangChain (in the repo examples/).

Try it: npx boffinit cursor

Also works with Claude Code, Codex, and OpenCode.

Happy to answer questions — especially if you have a place where the agent keeps "improving" load-bearing code.