The most-downloaded open System One reproduction. Merged Qwen3.5 fine-tunes, trained on about 95 public decision sets, then calibration-aware RL and a rank-64 LoRA, that softmax letter logits at an answer slot.
A rank-16 LoRA on Qwen3.5-4B built for the JevBench setting. A document, a policy and a question go in; a calibrated distribution over the option letters comes out of one forward pass. Research and demo use only.
Decides
choice, score, noul, classify, route
choice, score, noul, classify
Architecture
decider
hopper
Fine-tuned from
qwen/qwen3.5-2b-base
qwen/qwen3.5-4b
License
apache-2.0
Research and demo use only (training data includes RACE, non-commercial); serving code Apache-2.0
Availability
Open weights
Open weights
Hosted by
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Input price
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Decision accuracy
80.2%
68.5%
Calibration error
0.038
0.102
Valid action rate
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Median latency
3.2 ms
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p95 latency
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Evaluation suite
Figures are from each model’s manifest; accuracy and latency are what the publishers report, on their own suites and hardware. Add a third model.
Questions
What is the difference between decider and hopper?
decider is from Mapika and hopper from HopitAI. Both have open weights you can download and run. Both answer choice, score, noul and classify questions. Only decider answers route. decider is the smaller model, at 2.0B parameters to 4.0B. decider is licensed apache-2.0; hopper, other.
Which is more accurate, decider or hopper?
They report on different suites — decider 80.2% on Decider 67-task regression set, hopper 68.5% on JevBench public hard tier (111 items, measured by the authors) — so the numbers do not rank them. Test both on your own labelled examples.
Which is cheaper, decider or hopper?
decider: Free (open weights). hopper: Free (open weights). Open weights cost nothing per call beyond your own hardware.
Can I run decider or hopper locally?
Yes, both: systemone pull mapika/decider and systemone pull hopit-ai/hopper download the weights.
Decider 67-task regression set
JevBench public hard tier (111 items, measured by the authors)
