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Mini-Jev — abirshhishirroy
A from-scratch Jev-style decision model on a frozen Qwen2.5-3B backbone with a custom decision head and hand-rolled LoRA adapters. It returns typed action distributions for routing, safety gating, and RAG filtering, reporting 83.38% accuracy at 23.95 ms p50 latency.
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- Oct 2026
This is one of several Jev listings for the same project. The canonical entry is mini-Jev — r-ms.
Highlights
- Frozen Qwen2.5-3B-Instruct backbone with a custom DecisionHead and hand-rolled LoRA adapters.
- Reports 83.38% overall accuracy versus 73.00% for GPT-4o-mini across its 7-task suite.
- p50 latency of 23.95 ms and ECE of 0.022 on the author's evaluation.
- Trained on a custom 35,769-example dataset; the full dataset is excluded from the repository.
- MIT licensed, built with Python 3.12, PyTorch 2.4, and HuggingFace Transformers.
Questions about this entry
Short answers drawn from the linked project or page.
State and candidates are concatenated into one sequence, passed through the frozen Qwen2.5-3B backbone, then a boolean mask mean-pools hidden states only over each candidate's tokens. A 2-layer MLP maps each pooled vector to a scalar logit, and a grouped softmax over candidates yields the final probabilities.
The README states the 3B parameter model fits on consumer GPUs, so no OpenAI or Anthropic API calls are required. Cost per 1,000 inferences is listed as $0.00 local, against roughly $0.30 for GPT-4o-mini.
No. The full dataset is excluded to keep the repository lightweight. The exact line format is shown in data/samples/train_sample.jsonl, with each line holding a task, state, candidate list, and correct_index.
The project is MIT licensed and targets Python 3.12 with PyTorch 2.4 and HuggingFace Transformers. The backbone is Qwen2.5-3B-Instruct, kept frozen while the decision head and LoRA adapters are trained.
The custom dataset spans 7 tasks, including safety gating, hallucination validation, context filtering, query routing, and tool routing. Reported per-task accuracy includes 97.32% on safety gating, 100.00% on query routing, and 76.67% on hallucination validation.
General tool routing, where it scores 82.33% against GPT-4o-mini's 89.75%. The author attributes this to the larger model's broad semantic understanding, while Mini-Jev leads on structured validation, strict rule-following, and safety tasks.
It serves as the decision engine for a CLI coding agent that writes Python unit tests, routing between read_file, grep_search, and run_bash while gating dangerous shell commands. It also filters retrieved chunks and validates faithfulness in an end-to-end RAG pipeline.
Reactions & coverage
Posts, threads, and videos about this entry from around the web.
Hacker News: ASTGL replay chose local Laya routing over hosted Jev on one Mac Studio setup.
Jmeg8r15 pointsDoes an open-weight decision model beat a hosted one? Jev vs. LayaRead the thread on Hacker NewsReddit: A walkthrough of routing between models with Jev.
X: Standard One SH (StandardThinking)
Facebook: Intake Router keeps diagnosis out of the answer space at the front desk.
FacebookClinicnotes
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