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.
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.
Nothing to install, Node 18+ and npx are enough:
npx jev-enforce check --as code src/orders.tsclaude plugin marketplace add erkamyaman/jev-enforce
claude plugin install jev-enforce@jev-enforceAdd your key (from console.typesafe.ai) to ~/.claude/settings.json:
{ "env": { "TYPESAFE_API_KEY": "..." } }No key, no checks. It cannot break a session.
- Reads the same rule files Claude Code does:
~/.claude/CLAUDE.md,CLAUDE.md,.claude/CLAUDE.md,CLAUDE.local.md,.claude/rules/**, andAGENTS.mdwhen 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
Stophook checks the final reply. APostToolUsehook checks Edit, Write and MultiEdit. - With
JEV_ENFORCE_MODE=end, edits are only recorded while Claude works. TheStophook 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.
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.txtThe CLI reads TYPESAFE_API_KEY from the environment, so it works in CI as a rule check on changed files.
| Env | Default | |
|---|---|---|
TYPESAFE_API_KEY |
none | Required |
JEV_ENFORCE_THRESHOLD |
0.7 |
How sure Jev must be before Claude is told |
JEV_ENFORCE_MODE |
turn |
end checks all edits once when the turn ends, instead of after each edit |
JEV_ENFORCE_OFF |
unset | 1 disables it |
59 labeled examples against 19 rules, half style and half architecture and security. Full output in bench/results.md, reproduce with npm run bench.
| Threshold | Precision | Recall | Clean texts wrongly flagged |
|---|---|---|---|
| 0.6 | 87.8% | 95.6% | 3 of 28 |
| 0.7 (default) | 93.3% | 93.3% | 2 of 28 |
| 0.8 | 95.3% | 91.1% | 2 of 28 |
| 0.9 | 97.4% | 84.4% | 1 of 28 |
348ms p50, $0.0027 for the whole run.
- 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
2019–2024as an em dash. - Dataflow.
prefer-construles 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
axiosimport, because it cannot see package.json. Editing an old migration scored 0.06. - Your reply text, edits and rules go to TypeSafe's API.
npm install
npm testTypeScript, 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).
If this saves you from one more "I told it not to do that" moment, you can sponsor the work.
MIT