jev-enforce

Claude Code plugin that checks every reply and every file edit against your CLAUDE.md (or AGENTS.md), using TypeSafe's Jev. Break a rule and Claude gets it quoted back and fixes it, in the same turn.

_{The handler it is checking is demo/src/orders.ts.}

Why

CLAUDE.md is context, not a constraint. It holds for a few turns, then a handler shows up with raw SQL in it and a test quietly becomes it.skip. Nothing checks the output against the rules, so this does.

Jev makes it cheap enough to run every turn: it answers typed yes/no questions instead of writing text, all of them in one request. One question per rule, about 350ms, about 3 cents per 1,000 checks.

Try it

Nothing to install, Node 18+ and npx are enough:

npx jev-enforce check --as code src/orders.ts

Install

claude plugin marketplace add erkamyaman/jev-enforce
claude plugin install jev-enforce@jev-enforce

Add your key (from console.typesafe.ai) to ~/.claude/settings.json:

{ "env": { "TYPESAFE_API_KEY": "..." } }

No key, no checks. It cannot break a session.

How it works

• Reads the same rule files Claude Code does: ~/.claude/CLAUDE.md, CLAUDE.md, .claude/CLAUDE.md, CLAUDE.local.md, .claude/rules/**, and AGENTS.md when the project has no CLAUDE.md, matching Claude Code's own precedence. Each bullet is one rule.
• Sorts each rule once, cached: does it constrain replies, code, both, or neither. Git and workflow rules land in neither and are skipped.
• A Stop hook checks the final reply. A PostToolUse hook checks Edit, Write and MultiEdit.
• With JEV_ENFORCE_MODE=end, edits are only recorded while Claude works. The Stop hook checks every edited file and the reply together, in parallel, so a turn pays for one check no matter how many edits it made.
• Broken rules come back as decision: "block" with the rules quoted, so Claude fixes it before you see it. Once per turn, so it cannot loop, which also means the fix itself is not re-checked.

CLI

Installed as a plugin, or through npx jev-enforce:

jev-enforce rules                          # your rules and how each was sorted
jev-enforce check --as code src/orders.ts  # exits 1 if a rule is broken
jev-enforce check --as reply message.txt

The CLI reads TYPESAFE_API_KEY from the environment, so it works in CI as a rule check on changed files.

Settings

Benchmark

59 labeled examples against 19 rules, half style and half architecture and security. Full output in bench/results.md, reproduce with npm run bench.

348ms p50, $0.0027 for the whole run.

What it is bad at

• It is a model, not a guarantee. At the default threshold about 1 in 15 flags is wrong and about 1 in 15 broken rules slips through.
• Exact characters. It read 2019–2024 as an em dash.
• Dataflow. prefer-const rules need a linter, not a model.
• Rules that depend on state outside the text. "Never add an npm dependency" scored 0.56 on a new axios import, because it cannot see package.json. Editing an old migration scored 0.06.
• Your reply text, edits and rules go to TypeSafe's API.

Development

npm install
npm test

TypeScript, no runtime dependencies, tests run offline against a fake Jev. dist/src/ is committed because Claude Code runs plugin hooks straight from the repo, so run npm run build before committing (npm run check-dist verifies).

Sponsor

If this saves you from one more "I told it not to do that" moment, you can sponsor the work.

License

MIT