jev-review-mcp

Code-review gate as a single-purpose MCP tool, powered by Jev (TypeSafe's System One decision model). One MCP, one job.

Real-world cost on OpenRouter — 4.9M tokens · $0.19 over 7 days:

Turns a git diff into a typed decision — no prose, no Jev API knowledge needed from the host agent.

What it does

review_patch(diff, context?) returns a structured verdict instead of free-form text:

Decision gate: action is auto_merge only when verdict === "approve" and safe_prob > 0.8 and confidence >= 0.6. Every other case is human_review.

⚠️ Only execute auto_merge on high confidence. A high safe_prob alone is never permission to merge — gate on confidence.

Related MCP server: secret-scanner

Install & build

npm install
npm run build

The compiled server is at dist/index.js.

Add to your MCP client

{
  "mcpServers": {
    "jev-review": {
      "command": "node",
      "args": ["/absolute/path/jev-review-mcp/dist/index.js"],
      "env": { "TYPESAFE_API_KEY": "ts_xxx" }
    }
  }
}

No key? It still runs in mock mode (JEV_MCP_MOCK=1, or simply no TYPESAFE_API_KEY) so you can try it offline.

Example call

{
  "diff": "diff --git a/src/app.ts b/src/app.ts\n- const x = secret\n+ const x = process.env.SECRET",
  "context": "Move hardcoded secret to an env var"
}

returns something like:

{
  "verdict": "request_changes",
  "safe_prob": 0.2,
  "severity_score": 4,
  "severity_label": "critical",
  "confidence": 0.7,
  "action": "human_review",
  "recommended": false
}

Model endpoint

Works with any Jev-compatible endpoint. Default is the TypeSafe API (https://api.typesafe.ai/v1/systemone); override with JEV_BASE_URL (e.g. an OpenRouter-compatible route) and set TYPESAFE_API_KEY to your provider key.

Environment variables

Mock mode

With no key (or JEV_MCP_MOCK=1) the server answers deterministically from keyword heuristics — useful for demos, tests, and offline development. A single derived risk signal drives every field, so the mock stays internally consistent (risky diff → low safe_prob, high severity, human_review).

Diagnostics

node dist/index.js doctor          # human-readable
node dist/index.js doctor --json   # machine-readable

Prints mock/live mode, key presence, model, and base URL.

Test

npm test

Runs a smoke test against the compiled output in deterministic mock mode.

Notes

• Jev is a decision model: pure text in → typed decision out. It does not read images or generate prose.

• Diffs are truncated at 60k characters to stay within Jev's ~64k-token budget.

• Keep the human in the loop: route anything that is not a high-confidence auto_merge to a person.

License

MIT