jev-router

Express with no routes. Jev picks which handler runs.

There is no GET /users/:id. Clients hit the origin. Method, path, and body are evidence. You register English + a named function. Jev’s Choice key is function.name so the payload stays small.

import express from 'express'
import { JevRouter } from 'jevexpress'

const api = JevRouter()

function listUsers(_req, res) {
  res.json({ users: [] })
}

function createUser(req, res) {
  res.status(201).json({ user: req.body })
}

api.handle('List users. Collection read; no body required.', listUsers)
api.handle('Create a user from JSON with name and/or email.', createUser)

const app = express()
app.use(express.json())
app.get('/health', (_req, res) => res.json({ ok: true }))
app.use(api)

What Jev sees:

{
  "listUsers": "List users. Collection read; no body required.",
  "createUser": "Create a user from JSON with name and/or email.",
  "none_of_the_above": "The request does not match any registered handler."
}

These can all run listUsers:

curl http://localhost:3000/users
curl http://localhost:3000/please-list-the-people
curl -X POST http://localhost:3000/ -H 'content-type: application/json' \
  -d '{"please":"list people"}'

handle takes two arguments only: the intent string, then the function. There is no id and no path. Inline arrows have no .name — use function listUsers(...).

Install

npm install jevexpress express

Node 20+. Jev is called through OpenRouter’s Decisions API, not chat completions:

export OPENROUTER_API_KEY=sk-or-...

Default model is typesafe/jev-1.13. Pass model: '~typesafe/jev-latest' to track current Jev.

How it works

1. handle(intent, namedFn) — no route table.
2. Every request except GET /health becomes { method, path, query, contentType, body }.
3. One Choice over the function names + none_of_the_above. The sentences are the criteria.
4. confidence < 0.65 or none_of_the_above → 404 with the probability dump.
5. Otherwise that function runs. Jev cannot invent a new handler.

Headers: X-Jev-Handler (the function name), X-Jev-Confidence, X-Jev-Model.

Put auth in front of app.use(api).

Options

JevRouter({
  minConfidence: 0.65,
  model: 'typesafe/jev-1.13',
  apiKey: process.env.OPENROUTER_API_KEY,
  skipPaths: ['/health'],
})

Limits

• Choice is capped at 255 options (254 handlers + none_of_the_above).
• Typical Jev latency is ~70–500ms.
• URLs are not the interface.
• Body is truncated (~4k chars). Do not minify handler names away.

Demo

export OPENROUTER_API_KEY=sk-or-...
npx tsx examples/demo.ts

License

MIT — github.com/carllippert/jev-router