Boffin (npm: boffinit) is a staff-engineer control layer for AI coding agents that routes architectural constraints to the exact file being edited and requires verification proportional to the change. Unlike static AGENTS.md files or prompt packs that ship one instruction block for the whole repository, Boffin selects only the constraints relevant to the current edit. Powered by Parsel Fire Core, it ships as a single npm package for Cursor, Claude Code, Codex, and Open Code.

The tool is explicit about what it is not: not a linter, CI gate, speed tool, or security sandbox. It acts before and after edits, delivering signed portable packs with readable, versioned markdown rules under packs/ that are GPG-signed. Every rule is inspectable before install.

Public case studies record guided refactors on real open-source code: Duck DB landed at +17 / -17 lines with 2,104 assertions passing across 8 test files; Fast API achieved +16 / -33 with 49 tests passing and no public API change; Lang Chain preserved the sync/async boundary with 4 tests passing. These are reproducible case studies, not controlled benchmarks.

Installation requires Node.js 18+. Profiles (lite, full, max) tune cleanup ambition, not correctness floors. Boffin does not replace tests or code review. Source: GitHub - Mic Sm/boffin, MIT License.