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EcosystemOpen-weight model

Open weights

Model checkpoints published for anyone to download, run, and fine-tune, as opposed to a hosted closed API like Jev.

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Category
Ecosystem
Also known as
Open-weight model
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Added
2026-10-10

Definition

Jev itself is closed-weight: TypeSafe publishes the API, not the checkpoint. The open ecosystem rebuilds the shape around it, and the Hugging Face hub carries hundreds of repositories tagged system-one, from 144M encoders to 27B and 31B students.

Open weights settle hosting, not honesty. Licenses differ, Apache-2.0 for most, CC BY-NC for some, custom terms for others, and calibration belongs to the downloader to verify: Laya's fine-tuned checkpoint reaches 0.766 where its base checkpoint sits at 0.362.

Tagsopen-modelsmodels

Related terms

Definitions that connect to this one.

RLCDTypeSafe's post-training method: reinforcement learning that optimizes for calibrated decisions and probabilities instead of generated text.Evaluation & TrainingBrier scoreA score for a full probability vector against one observed label. Lower is better, and a confident wrong answer costs more than a hedge.Evaluation & TrainingCalibrationThe property that outcomes given a probability of 0.2 occur about 20% of the time, measured across many predictions.Answers & ConfidenceLocal decision serverA process on your machine that answers typed questions from local weights, so the state does not leave the host.EcosystemSystem OneThe class of AI models built to make fast, structured decisions software can use directly, named after Kahneman's fast-thinking System 1.Core Concepts

From the Jev directory

Laya on Hugging Face
The Hugging Face hub for Laya's open System 1 checkpoints: the 421M English model at the repo root, a 322M multilingual build in a subfolder, and the typed-decisions fine-tune, all Apache-2.0.
Jev Models & Reimplementations#community#open-models#local
Community
AutoTrust JEV-27B
An open distillation of Jev 1.13 onto Qwen3.8-27B: a 108.9M-parameter decision block answers typed questions in one prefill pass and adds a POST /v1/decide route beside a full System 2.
Jev Models & Reimplementations#community#open-models#local
Community
Julia 1
Supersonic Labs' 144.3M-parameter decision model on mmBERT-small: choice, score, and noul answers from supplied options in one pass, 73.15% on 2,000 typed decisions, Apache-2.0.
Jev Models & Reimplementations#community#open-models#local
Community
ComfyUI-SystemOne
2GitHub stars
A ComfyUI node pack that branches a generation workflow on a plain-English question such as whether an image is too graphic for kids, running locally on Laya by default or Jev on a dropdown switch.
Jev Integrations & Adapters#community#comfyui#python
Communitydante01yoon/ComfyUI-SystemOnePython
Train your own decision model with Unsloth
Unsloth's guide to turning a generative LLM into a Jev-style decision model that returns a choice with a probability instead of text, plus a companion page for serving Laya behind the TypeSafe API.
Jev Models & Reimplementations#community#fine-tuning#open-models
Community
Decision models on Router+
A router playground that serves several System One decision models from one place: Jev, Perplexity's Decider, Bespoke Nimble, Mercury Decide, Clef, Kev 4B, and Decider 2B, with three of them free.
Jev Integrations & Adapters#community#router#api
Community

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