Deterministic outputs for Jev decisions
Deterministic, in a Jev integration, means two different things people mix up. The schema is deterministic: you cannot get a key outside criteria. The numbers are not a cryptographic hash. Pin the model, freeze questions, and you get a replayable contract — not a promise that 0.812 never becomes 0.807 after a weight change.
This page is for builders who already heard of Jev / System One and want a production-minded mental model. jev.pro is an independent unofficial field guide — not affiliated with TypeSafe AI. Confirm facts on docs.typesafe.ai. We do not sell keys.
Definition: closed set vs bit-identical
Jev is TypeSafe’s first public System One model. Choice, Score, and Noul return typed fields. Code owns control flow. That is the TypeSafe product contract — no free-text rationale, no invented enum. See why Jev gives up generation.
TypeSafe’s launch post calls type errors “mathematically impossible” for this interface. That is schema matching. Schema-safe ≠ correct. A closed enum can still be the wrong department. “Can’t hallucinate” is not factual correctness and is not bit-stability.
Public System One docs we used do not expose a temperature knob like chat APIs. Do not invent one.
Mental model: freeze the contract you actually replay
- Versioned model id (
jev-1.13.0), not onlyjev-latest. Aliases move. - The questions module (instructions, criteria). Wording is literal on 1.13.
- Filtered
state(or a hash + store). All questions see that same state. - Your thresholds — they are part of the verdict.
Replay is your POST, not a hidden /v1/replay. Compare actions, not only argmax, when you promote. Small float drift is possible unless TypeSafe documents bit-stability. Design floors with margin. See decision quality.
What is closed, what is not
| Surface | Closed? | Notes |
|---|---|---|
| Choice option set | Yes | Cannot emit an option you did not list |
| Score levels | Yes | Cannot invent an 11th level |
| Noul range | Yes | Float in [0, 1] |
| Probability digits | No promise | Do not treat as a hash |
| Factual truth | No | Schema-safe ≠ correct |
Keep arithmetic in code. Jaggedness: jev-1.13 is weak at numeric precision, extra indirection, and overly literal wording. If two replays disagree because you asked Jev to add invoices, that is your design, not a determinism bug.
Version pins and aliases
As of the public models page, jev-latest and jev-preview pointed at jev-1.13.0. The response model field reports the versioned id that answered. Log it. If you fitted confidence floors on 1.13.0, do not silently ride an alias into 1.14.
Vendor envelope (label it): $0.042/M input, output free; 70ms–500ms; 64k / 32k context. Those figures are not a determinism SLA.
See also
FAQ
Can I set temperature 0?
Public System One docs we used do not expose a temperature knob like chat APIs. Do not invent one.
Same state, same pin, different day?
Treat small float drift as possible unless TypeSafe documents bit-stability. Design floors with margin.
Is schema-safe deterministic truth?
No. Schema-safe ≠ factually correct.
Does pinning freeze my policy outcome?
It freezes weights. Change extracted policy text in state or a threshold and the action can change even if argmax stays put.
Disclaimer
This is an independent unofficial site and is not affiliated with TypeSafe AI; official documentation is available at https://docs.typesafe.ai. Never treat jev.pro as TypeSafe official documentation. We do not sell, issue, or proxy API keys.