Jev guides: read this before you paste a schema

The Jev guides on this site are the missing layer between TypeSafe’s official API reference and a pile of JSON. If you skip them, you will treat a Noul of 0.5 as “medium,” round a Score, and ask Jev to write an apology. The catalog will still copy. Your router will still lie.

Five Jev guides, in the order we would hand them to a new teammate: what Jev is (the product contract), where to call Jev (TypeSafe console, OpenRouter, Vercel, Cloudflare, Venice, Netlify, AI/ML API, LiteLLM), Choice / Score / Noul (the only three question types), confidence thresholds (where policy lives), and when not to use Jev (the boundary with writers, chat, and vision). Then open the catalog or Jev Studio.

These Jev guides quote vendor figures — latency, price, aliases — from public vendor documentation as of 21 September 2026. Re-check docs.typesafe.ai before you freeze capacity math. Jev Patterns is not affiliated with TypeSafe AI and does not host the model.

How the Jev guides connect to patterns

Each pattern page assumes you know the primitives. Support ticket routing is a Choice plus a Noul. Urgency scoring is a Score. The LLM output guardrail mixes a Noul and a Choice. If that sentence is opaque, the Jev guides are the fix — not a longer prompt. Compare pages sit beside the guides: Jev vs ChatGPT, JSON mode, function calling.

If you only read one Jev guide, read when not to use Jev. The rest of the internet will try to make System One sound like a smaller chatbot. It is not. About this project: about.

Suggested path through the Jev guides

Day one: What is Jev, Where to call Jev, plus a single Studio fixture — support ticket routing is the least abstract. Day two: Choice, Score, Noul until you can say why urgency is a Score and is_urgent is a Noul. Day three: put 0.75 in config and try to argue it down with labels. Day four: when not to use Jev, taped above the laptop, while someone asks you to generate the apology email. That is the whole onboarding. The Jev guides are short on purpose; the catalog is where the JSON lives.

If you are migrating off JSON mode, read the compare pages in parallel with these Jev guides. The primitives guide tells you what to ask. Jev vs JSON mode tells you why the old parser still feels necessary until you delete the enum fields. Do not skip either.

Questions the Jev guides answer that official docs assume

Official docs tell you the request shape. They do not tell you that a Noul of 0.5 is not a yellow SLA, that Score 2.14 should not round, that you should not ask Jev to write the apology, or that aliases move and take your thresholds with them. Those are the Jev guides. If you only read TypeSafe’s introduction you will still paste a writer prompt.

Bookmark this hub. Send it to the person who asked for “ChatGPT on every ticket.” Then send when not to use Jev. Then send a catalog card. That sequence is the whole enablement plan. Jev guides stay short so they get read. The JSON stays on pattern pages so it gets copied. Studio stays a fixture so nobody bills a demo.