Deploy Jev Lite

Deploy and Host

Jev Lite is a self-hosted proxy + web console for TypeSafe's Jev (System One) decision API — turn freeform application state and a set of structured questions into a typed model call, then read back a clean JSON verdict.

This template ships the whole client in one container: a thin FastAPI proxy plus a single-file web console. No model weights, no GPU, no database, no companion service — the container is stateless and lightweight (~180 MB). Your TypeSafe API key stays server-side; the browser never sees it.

• Web console: / (build state + questions, read the verdict)
• API: POST /v1/decide with {state, questions, model?} (also GET /v1/status, GET /v1/models)
• /health — liveness + key_configured flag, unauthenticated (Railway healthcheck target)
• Optional lock-down: AUTH_TOKEN, when set, gates the UI and every /v1 endpoint with Authorization: Bearer *** (or ?token=*** on the UI URL)

Why Deploy

Jev (System One) is TypeSafe's hosted decision model — you hand it the current state of an application plus a small set of typed questions (yes/no, choice, score) and get back a structured verdict with per-question answers. That is the shape of a lot of "should I take this action?" logic, but it needs a stable, typed surface between your front-end and the hosted model.

• One click — no model to host, no GPU, no database, no companion service. One stateless container on the Hobby plan
• Server-side key — the proxy holds TYPESAFE_API_KEY and forwards it to the model; the browser and the deploy page never see it
• Typed, verifiable API — requests are validated locally (fast, clear 400s with a shape hint), forwarded as-is, and upstream error semantics are mapped to stable client errors
• Web console — a single self-contained page that builds the state + questions and shows the verdict, with optional token lock-down
• No state to lose — no volume, no storage; a redeploy is a clean re-run

About Hosting

Single service, Dockerfile build from the pinned python:3.12-slim base:

1. Pinned dependency layer — fastapi, uvicorn[standard], httpx installed once; only the app code changes
2. Non-root runtime — the container runs as uid 1000. There is no volume mounted, so there is nothing root-owned to collide with (the Railway volume EACCES trap only applies to mounted paths)
3. Shell-form CMD — exec uvicorn … --port ${PORT:-8080} so the PORT variable Railway injects is expanded at container start
4. In-image healthcheck — python probes /health on PORT with a 20 s start period, matching the railway.json builder

No volume is created: the client is fully stateless.

Dependencies for Jev Lite

Deployment Dependencies

One external service — TypeSafe Jev (System One). All the app needs from it is an API key and outbound internet access to api.typesafe.ai:

The service boots and serves the UI and /health without a key — /v1/decide and /v1/models return a clear no_api_key error (with a hint pointing at the console) until you set TYPESAFE_API_KEY and redeploy. So you can always confirm the deployment is live before wiring in a key.

Ports

• 8080 — web console + API; /health for the Railway healthcheck

Common Use Cases

• A private decision endpoint in front of TypeSafe, with your front-end posting typed questions instead of raw prompt text
• An opinionated, validated proxy that keeps your client key server-side and returns stable, documented error codes
• A lockable web console (via AUTH_TOKEN) for a shared instance where only token holders can drive /v1/decide
• A reference shape for wrapping a hosted "state + questions → verdict" model behind a small, auditable API