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CommunityJev Models & Reimplementations
JEV from Scratch
An independent, from-scratch reconstruction of a Jev-style decision model that never generates text: a state plus typed questions returns a probability for every option. Trained on Qwen3-0.6B and 1.7B backbones with LoRA and served through a system_one-shaped API.
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- Oct 2026
Highlights
- A reconstruction of Jev's publicly inferred design; TypeSafe has not published Jev's weights or architecture.
- Built and tested on a laptop RTX 4070 with 8 GB, using Qwen3-0.6B and Qwen3-1.7B backbones.
- LoRA r=16 / alpha=32 on all 7 projections; 10.62M of 606.7M parameters trained in the 0.6B runs.
- The final broad2_1p7b run trains on 22,000 questions; the broad run reports 96.3% choice accuracy and 0.022 ECE.
- Serves POST /v1/systemone with the same request and response shape as TypeSafe's system_one.
Questions about this entry
Short answers drawn from the linked project or page.
No. The repository states plainly that it is not Jev: TypeSafe has not published Jev's weights or architecture. It is the author's own reconstruction of the publicly inferred design, based on TypeSafe's launch post, Archer Hume's write-up on Jev's architecture, and the open-source Kev project.
The runs were built and tested on a laptop RTX 4070 with 8 GB of memory, using torch 2.9.1+cu130, transformers 4.57.3 and peft 0.21.2. Training runs took roughly 12 to 65 minutes each, with the 1.7B broad2 runs the longest.
Text is encoded with borrowed Qwen special tokens as delimiters, every option restarts at the same position, and a 4D additive mask lets options see the context and themselves but never each other. A pointer head scores DECIDE against each option close token, so no per-label weights are needed.
Choice questions return a probability over the given options, noul is implemented as a two-way no/yes question returning P(yes), and score questions take ordered levels and return the expected level computed as the sum of index times probability.
Metrics are generated by python -m src.report from JSON in outputs, covering accuracy, ECE, Brier and NLL per question type after temperature scaling. The broad run reports 96.3% choice accuracy with 0.022 ECE, and the plus run reports 94.0% on the harder score condition.
Yes. src/api.py and src/serve.py provide POST /v1/systemone with the same request and response shape as TypeSafe's system_one. An optional packed inference path puts one state and many questions in a single sequence with a state KV cache, matching separate rows to about 1e-6 in fp32.
It is a laptop-scale reconstruction, not an official model, and the reported numbers come from a single seed with 300 questions per condition unless noted. Dataset licences are documented in DATA_LICENSES.md, and the lab notebook records every experiment, number and mistake in order.
Reactions & coverage
Posts, threads, and videos about this entry from around the web.
X: Standard One SH (StandardThinking)
LinkedIn: What multimodal decision models actually change, and what they do not.
LinkedInJevDirectory.org
Hacker News: Decision Index 0.2.1 scores open reproductions of Jev on a frozen suite.
jackbravo4 pointsDecision Index 0.2.1 – 70 open reproductions of TypeSafe Jev's Decision ModelRead the thread on Hacker NewsHacker News: Pointer to a DiffusionGemma plus vLLM tutorial for a Jev-shaped classifier.
1 pointHow to build a Jev-style classifier with DiffusionGemma and vLLMRead the thread on Hacker NewsFrom the Jev guides
Original write-ups on what this entry is for.
From the Jev AI model community
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