How to Build a Decision Model Like Jev
Antonello Fratepietro ● Covered by 2 sources
The article explains how decision models using the /v1/systemone contract score probabilities for predefined outcomes without running token-by-token text generation. Hugging Face merged native /v1/systemone support into transformers serve, covering 250+ open LLM and VLM architectures. As a result, serving can use a single prefill pass (output_tokens: 0) to return calibrated choice/noul/score distributions instead of paying the decode tax and relying on JSON text parsing.
Why it matters
Decision models return probabilities over known outcomes in a single forward pass, avoiding chat-generation and JSON parsing overhead. It walks through building such a system starting from Hugging Face’s /v1/systemone endpoint, including calibration and tree batching.
Related stories
Jev introduces a new shape of LLM - System One, aka Decision Models
Simon Willison’s Weblog · 1 month ago ·
35
TypeSafe AI Releases Jev: A System One Model That Returns Typed, Calibrated Decisions Instead of Text
MarkTechPost · 1 month ago ·
8
Jev's Architecture Unmasked
Archer Hume · 1 month ago ·
10