Boffin (npm: boffinit) is a staff-engineer control layer for AI coding agents: it feeds the agent the architectural constraints for the exact file it is editing and makes it verify the result -- DuckDB case study: a guided refactor landed at +17 / -17 lines with 2,104 assertions passing.

You ask for a 15-line fix; the agent comes back with a 500-line renovation. Boffin gives the agent the architectural constraints that apply to the file it is about to touch, then makes it verify the result.

It is not another AGENTS.md and not a prompt pack. Those formats usually ship one static instructions block for the whole repository; Boffin routes only the constraints relevant to the current edit. Powered by ParselFire Core.

• Not a static repo-wide rules file (AGENTS.md-style one block for everything)
• Not a prompt pack or system-prompt trick
• Not a linter or CI gate -- it acts before and after the edit
• Not a speed tool -- the frame is review-safety

• Selects the constraints relevant to the edit in front of the agent
• Requires verification proportional to the change
• Ships for Cursor, Claude Code, Codex, and OpenCode from one npm package
• Delivers signed portable packs powered by ParselFire Core

The public case studies record these guided refactors on real open-source code:

• DuckDB: +17 / -17; 2,104 assertions across 8 test files passed; distinct continuation and recovery paths were preserved.
• FastAPI: +16 / -33; 49 tests passed; no public API change.
• LangChain: the sync/async boundary was preserved; 4 tests passed.

These are reproducible case studies, not a controlled A/B benchmark.

Boffin requires Node.js 18 or newer.

Run from your project:

Run these inside Claude Code:

/plugin marketplace add MicSm/boffin
/plugin install boffin@boffin

Run these from a terminal:

codex plugin marketplace add MicSm/boffin
codex plugin add boffin@boffin

Codex does not trust plugin hooks automatically. Run /hooks once inside Codex to review and trust Boffin's hooks; until then the plugin's skills work but the automatic per-session activation stays off.

Run from your project:

Then open the project in OpenCode. Always-on guidance lands via opencode.json -> .boffin/AGENTS.md. On demand: /boffin, /boffin-review, or the boffin / boffin-review skills.

Install details, commands, and troubleshooting: OpenCode delivery.

Want the machinery? Read how ParselFire Core works.

Similar code is not always the same code. Boffin gives the agent a reason to stop before it merges a real special case, blurs a sync/async boundary, moves state away from its owner, or turns a focused task into a tour of the codebase.

• For a focused change, it keeps the requested scope small and asks for the narrowest check that proves the edit.
• For an open-ended refactor or review, it requires a read-only audit first, followed by one verified finding at a time.
• When cleanup conflicts with an earlier correctness rule, correctness wins.

The point is not to make the agent timid. It is to make the expensive details explicit before they become an interesting afternoon.

AGENTS.md is usually one static instructions file for the whole repository. Boffin routes only the architectural constraints relevant to the file the agent is about to edit, then requires a check proportional to the change.

Every rule ships in this repository as readable, versioned markdown under packs/, and the packs are GPG-signed. Nothing is hidden at install time: open any pack and read every rule before trusting it. At edit time Boffin selects which of those rules apply to the file being touched. See how ParselFire Core works for the routing map.

You ask for a small fix; the agent comes back with a renovation. Boffin injects the load-bearing constraints for the current file before the edit and forces verification afterward.

They tune cleanup ambition, not correctness:

• lite keeps cleanup pressure low and favors the smallest useful change.
• full is the balanced default.
• max applies the strongest cleanup pressure when the task justifies it.

On plugin hosts, select a profile with /boffin lite, /boffin full, or /boffin max. There is no off profile.

No. Every profile keeps the same early correctness stages and rejection rules, including trust-boundary validation, data-loss prevention, security, and accessibility requirements.

No. Boffin does not isolate processes, filter shell commands, or restrict filesystem or network access. It guides architectural decisions in generated code. Use command sandboxes and security controls for their own job; Boffin has a different job.

npx boffinit cursor uninstall
npx boffinit opencode uninstall

Each uninstaller removes that host's managed files only. Shared .boffin/packs and .boffin/VERSION stay if the other host is still installed. Unrelated project files are left alone.

No. It tells the agent which contracts deserve attention and requires external checks, but your repository's tests and review process remain authoritative.

Portable adapters cover hosts that read AGENTS.md, CLAUDE.md, workspace rules, or repository instructions. See host delivery and adapters for the technical map.

Boffin is available under the MIT License. See credits.