JEV FIELD MANUAL

Learn TypeSafe’s Jev — a decision model that doesn’t chat — plus the community tools around it.

Jev returns typed Choice / Score / Boolean answers with calibrated confidence. This hub maps a quick start, capability boundaries, ecosystem tools, and starter use cases. We are not affiliated with TypeSafe.

  • 5 linked quick-start guides
  • 22 curated use cases with full prompts
  • Ecosystem map: TypeSafe, Gateway, SemIf, …
  • A JSON feed your bot can subscribe to

Quick Start

What Jev is → access paths → one evaluate call → confidence thresholds → hard boundaries.

01

What is Jev?

TypeSafe’s first System One model: state + typed questions in → decisions + probabilities out — no chat text.

  • Built for software automation, not human chat (TypeSafe manifesto / launch post)
  • Question types: Choice, Score, Boolean (Vercel Gateway docs)
  • Early access / waitlist as of Sep 2026 — re-check typesafe.ai

02

Get access (TypeSafe or Vercel AI Gateway)

Two public paths — TypeSafe console key, or call typesafe-ai/jev via Vercel AI Gateway.

  • Official API cited publicly: POST https://api.typesafe.ai/v1/systemone, model jev-latest — re-check live docs
  • Gateway model id: typesafe-ai/jev; AI SDK experimental_evaluate (Vercel changelog 2026-09-16)
  • Pricing claim on TypeSafe site: $0.042 / M input tokens, output free — operator-published; re-check live pricing

03

Run one evaluate call

Send shared state + a map of named questions; read typed answers and confidence in code.

  • Prefer official SDKs / AI SDK evaluate API over hand-rolled parsers
  • Keep questions narrow; put branching logic in your code
  • Never paste API keys into content pages

04

Threshold confidence, then act or escalate

Every answer includes calibrated confidence — automate high confidence, escalate the rest.

  • TypeSafe markets RLCD for calibrated decisions (launch post)
  • Probabilities ≠ proof; calibrate on your labeled workflow
  • Low confidence → human review or LLM fallback (pattern, not a TypeSafe SLA)

05

What Jev is not

Jev does not generate prose, code, or free-form tool strings — surrounding code owns loops and safety.

  • Not an LLM chat model; not a screenshot-native VLM by default
  • OpenJev / SemIf reproduce an interface pattern, not Jev weights (repo disclaimers)
  • Official jaggedness / limitations docs — link when URL confirmed in TypeSafe Docs

Starter use cases (outline only).

Thin placeholders you can adapt — not production recipes, and not invented benchmarks.

All use cases (5)

Ecosystem tools.

Official TypeSafe / Gateway paths, plus independent community projects (OpenJev→SemIf, computer-use, Unclutter). SimpleJev held until a public URL is locked.

Ecosystem (5)

Learn the deeper boundaries.

System One vs LLMs, question composition, confidence failure modes, and computer-use patterns.

Open Learn hub (2)

ecosystem

Ecosystem map: Jev, Gateway, OpenJev

Official TypeSafe Jev, Vercel AI Gateway access, and community OpenJev experiments — keep the labels straight.

foundations

System One vs an LLM

Jev selects typed decisions with probabilities. LLMs generate text. Use both — do not force one job onto the other.

CONNECT

Wire Jev into agents.

Prefer one evaluate call with many typed questions; keep thresholds in config; let an LLM write only when prose is required.

Get the bot contract →

Diagnose by symptom.

Wrong model id, OpenJev≠Jev confusion, over-automating low confidence, expecting chat prose.

Open troubleshoot (1)

Local OpenJev probabilities look decisive, but TypeSafe Jev (or humans) disagree on the same rows.

OpenJev results look like confidence but production disagrees

OpenJev documents uncalibrated option softmax. Do not treat it as TypeSafe calibrated confidence.