JPT-0.8B

License JevBench v1.4 public Decision Index 0.2.1 llm2jev

JPT-0.8B ยท JPT-4B ยท JPT-9B ยท JPT-35B-A3B ยท llm2jev

What is JPT-0.8B

JPT-0.8B is a fast, open decision model: give it a situation and typed questions, get a calibrated probability for every option from one forward pass. No generated explanation, no reasoning tokens โ€” latency is one prefill.

The small sibling of JPT-4B: the same recipe and the same data, small enough for CPU or edge serving.

It implements the typed-decision interface introduced by Jev from TypeSafe AI [1]: a caller sends a state plus questions, and each question is one of three types. JPT is an independent model, not derived from Jev and not trained on Jev outputs; it is an open alternative behind the same interface.

Question type What it answers Options
choice pick one 2โ€“255 labels
score a level on an ordered scale the scale's levels
noul yes / no true, false

Built on Qwen/Qwen3.5-0.8B: a LoRA fine-tune merged into full weights. The vision tower is unchanged.

Probabilities use one temperature T = 1.140, fit once on a held-out split โ€” never per benchmark.

โฏโฏ Benchmarks

โฏ JevBench v1.4.0

JevBench [2] scores general typed decisions; JPT-0.8B reaches 0.736 public accuracy, above every sub-2B system in the v1.4 results and 0.113 above its base model. v1.4.0 has 231 public items and 308 sealed items only the maintainer can run, so JPT-0.8B has no official v1.4 score yet.

JevBench v1.4.0 public accuracy

Table
System Params Public accuracy (231)
JPT-35B-A3B (ours) 35B-A3B 0.892
JPT-4B (ours) 4B 0.879
Jev 1.13.0 (TypeSafe AI, API) closed 0.866
JPT-9B (ours) 9B 0.853
JPT-0.8B 0.8B 0.736
decider-2b 2B 0.710
kev 0.6B 0.6B 0.667
Open-Jev 2B 2B 0.645
Qwen3.5-0.8B, same prompt, zero-shot (our run) 0.8B 0.623
SimpleJev (Qwen3.5-0.8B) 0.8B 0.545
kev 0.5B 0.5B 0.494

Source: other rows from results/v1.4/jevbench-v1.4-results.json at jevbench commit 2fa63fa (2026-09-23); ours scored with the benchmark's own CLI.

โฏ Decision Index 0.2.1

Decision Index [3] 0.2.1 (2026-09-27) is the broadest test: the full frozen suite, 38 scored benchmarks in five areas, chance-corrected โ€” JPT-0.8B scores 19.22, the best 0.8B on the board. Run through llm2jev over SGLang and submitted as apolinario/decision-index#7; 0.2.1 rescores the same run (17.07 under 0.2).

Decision Index 0.2.1

Table
Model Params Decision Index 0.2.1
Jev 1.13.0 (TypeSafe AI, API) closed 57.91
JPT-35B-A3B (ours, not on the board yet) 35B-A3B 52.89
JPT-0.8B 0.8B 19.22
Decision 1.0 Eos 0.8B 18.41
Kev 0.8B 0.8B 14.60
MoJev 0.8B 11.69

Source: live board data/index-v0.2.1.json (generated 2026-09-27 16:59 UTC); full run and scores.json in kirp/decision-index-results-jpt-0.8b (gated: it carries the suite's GPQA/HLE item text).

By area, against Jev 1.13.0 on the same items and scorer: JPT-0.8B is behind Jev in all five areas and ahead of it on 1 of the 38 index benchmarks.

Decision Index 0.2.1 by area

Per-area and per-benchmark skill vs Jev 1.13.0
Area Jev 1.13.0 JPT-0.8B
Knowledge 51.4 9.9
Language 62.0 23.0
Retrieval 55.4 16.4
Tools 75.1 36.2
Arts 37.7 8.0
Area Benchmark Jev 1.13.0 JPT-0.8B
Arts BPoMP 81.8 0.0
Arts ForecastBench 30.6 5.8
Arts Habermas Machine 21.5 12.1
Arts Humicroedit 23.7 4.4
Arts New Yorker 62.6 25.2
Arts POP909-CL 15.9 1.7
Arts cfcolor 28.8 7.2
Games ChessBench 9.8 0.3
Knowledge BBH 89.7 21.2
Knowledge CLadder 45.3 8.8
Knowledge CRUXEval 57.1 0.0
Knowledge GPQA Diamond 71.4 6.8
Knowledge GSM8K 75.6 20.7
Knowledge HLE 4.7 0.9
Knowledge MMLU-Pro 80.5 19.0
Knowledge MuSR 46.1 16.7
Knowledge SATA-Bench 25.4 2.7
Language ACOS 27.3 4.4
Language ANLI 62.2 8.0
Language ContractNLI 59.1 60.6
Language FinEntity 80.8 67.7
Language HellaSwag 92.7 31.5
Language NLI4CT 69.0 27.7
Language RAGTruth 51.3 7.4
Language VAST 46.9 16.0
Language WinoGrande 83.9 6.4
Language iSarcasmEval 36.3 5.5
Retrieval Amazon ESCI 43.8 12.3
Retrieval BANKING77 79.5 34.6
Retrieval BRIGHT 40.6 23.9
Retrieval CLINC150+OOS 89.2 9.9
Retrieval HoVer 45.7 9.7
Retrieval PhishNChips phishing decisions 25.1 4.1
Tools API-Bank 88.0 28.8
Tools BFCL 94.3 68.6
Tools Home appliance simulator 52.3 0.0
Tools ToolRet 59.9 45.6
Tools When2Call 74.6 33.3

Chance-corrected skill ร— 100 (0 = random, 100 = perfect). Jev's numbers are its official entry on the live board (jev-1.13.0); ours are from the same kit and suite.

โฏ More benchmarks

The same evals as the larger JPTs, at T = 1.140. Same-prompt base-model rows have not been run for these at 0.8B.

Benchmark (version, n) What it tests JPT-0.8B Jev 1.13.0
JevBench v1.4.0 public hard tier [2] (111) hardest general decisions 0.577 (ECE 0.156) โ€”
Typed decisions test (ours, 2,000) in-distribution typed decisions 0.768 (ECE 0.162) โ€”
ANLI r1 / r3 [4] (dev) adversarial NLI 0.437 / 0.483 โ€”
Banking77 [5] / MASSIVE 1.1 [6] (en / de / zh) intent classification 0.650 / 0.797 / 0.697 / 0.760 โ€”
EnvBench v0.1 (ours) public / held-out [10] (skill 0โ€“100) sequential decisions in game envs 37.8 / 35.0 โ€”
ScreenSpot-v2 [7] SoM / Screen2Words [8] / ERQA [9] (images, zero-shot) GUI grounding, screen summary, embodied reasoning 0.787 / 0.740 / 0.302 โ€”

Jev 1.13.0 has no official score on these splits (our own test/dev cuts, EnvBench, and the image sets), so its column is "โ€”"; its official scores on the Decision Index versions of ANLI and BANKING77 are in the per-benchmark table above. Running the Jev API on these splits would fill them.

Banking77, MASSIVE and typed rows are in-distribution (train splits in the mix, test items not).

โฏโฏ Quick Start

Two pieces: an engine that holds the weights, and llm2jev (>= 0.6.1) in front of it, reading option probabilities off the engine.

โšก SGLang (recommended)

python -m sglang.launch_server --model-path kirp/jpt-0.8b --port 30000 \
  --context-length 32768 --mamba-scheduler-strategy extra_buffer &  # Qwen3.5's DeltaNet layers need this flag
llm2jev --model kirp/jpt-0.8b --backend sglang --url http://127.0.0.1:30000 --port 8080 --temperature 1.140

Tested with SGLang 0.5.9; install cuDNN 9.15+ over its pinned 9.10: pip install "sglang==0.5.9" && pip install "nvidia-cudnn-cu12>=9.15".

๐Ÿ” vLLM

vllm serve kirp/jpt-0.8b --max-logprobs 256 --return-tokens-as-token-ids --enable-scale-out --port 8000
llm2jev --model kirp/jpt-0.8b --backend vllm --url http://127.0.0.1:8000 --port 8080 --temperature 1.140

The three vLLM flags are required: without them every request is a bare HTTP 400.

๐Ÿงช No engine (quick check only)

pip install "llm2jev[hf,vision]"
llm2jev --model kirp/jpt-0.8b --backend hf --port 8080 --temperature 1.140

Serializes requests; fine on CPU at this size, for traffic use SGLang or vLLM.

๐Ÿ“จ Ask it a question

import requests
r = requests.post("http://127.0.0.1:8080/v1/systemone", json={
    "state": "Refund policy: full refund within 30 days of purchase; 50% until day 60; none after.\n"
             "Order 1182 was bought on 3 March and returned on 20 April.",
    "questions": {
        "refund": {"type": "choice", "instructions": "What refund does order 1182 get?",
                   "criteria": {"full": "Full refund", "half": "50% refund", "none": "No refund"}},
        "late":   {"type": "noul", "instructions": "Was the return made after day 30?",
                   "criteria": {"true": "Yes", "false": "No"}}}})
print(r.json()["answers"])   # each answer has the per-option probabilities

๐Ÿ–ผ๏ธ With images

state = [{"role": "user", "content": [
    {"type": "image", "image": "https://example.com/screen.png"},
    {"type": "text", "text": "Task: open the settings page. Numbered boxes mark clickable elements."}]}]
questions = {"click": {"type": "choice", "instructions": "Which box should be clicked?",
                       "criteria": {"1": None, "2": None, "3": None, "4": None, "5": None}}}

โฏโฏ Training

The JPT-4B recipe and data (mix_train_env_v11, 49,221 typed questions) on a larger base, one epoch, merged into full weights.

Part What it is
Method LoRA r=16 on every attention, DeltaNet and MLP projection of the language model, lr 5e-5; vision tower untouched
Loss multi-class Brier over the option labels, on llm2jev's chat prompt with thinking disabled
Batch 2 GPUs ร— 5 ร— 4 gradient-accumulation steps = 40 questions per step
Data 49,221 questions in 32,835 records; one epoch over two option-shuffled copies โ€” sources on the JPT-4B card
Held out no item from JevBench, EnvBench held-out seeds, the Decision Index frozen suite or our typed test split

โฏโฏ Limitations

  • Much weaker than JPT-4B on hard questions: long-document and multi-step decisions (hard tier 0.577 vs 0.784).
  • Adversarial NLI is weak (ANLI r1 0.437).
  • Arithmetic and dates are the weakest area at every size: no reasoning phase by design.
  • Up to 255 options are accepted; training covered up to 77. English first. Images are zero-shot.

โฏโฏ References

  1. TypeSafe AI. Jev. https://typesafe.ai
  2. F. Standhartinger. JevBench, v1.4.0. https://github.com/fstandhartinger/jevbench
  3. Decision Index, edition 0.2.1. https://huggingface.co/spaces/multimodalart/jev-decision-index
  4. Nie et al. Adversarial NLI. ACL 2020.
  5. Casanueva et al. Efficient Intent Detection with Dual Sentence Encoders (Banking77). NLP4ConvAI 2020.
  6. FitzGerald et al. MASSIVE. ACL 2023.
  7. Wu et al. OS-Atlas (ScreenSpot-v2). 2024.
  8. Wang et al. Screen2Words. UIST 2021.
  9. Gemini Robotics Team. Gemini Robotics (ERQA). 2025.
  10. EnvBench, v0.1 (ours, frozen 2026-09-23; not yet public): programmatically solved game, planning and rule decisions with exact gold answers.

โฏโฏ License

CC BY-NC 4.0. The weights derive from Qwen3.5-0.8B (Apache-2.0), but some training datasets allow only non-commercial or research use, so the model is released for non-commercial use.


JPT-0.8B is an independent open model that implements a typed-decision interface (noul, choice and score questions answered with probabilities). It is not affiliated with, endorsed by or derived from TypeSafe AI or its Jev model, and it was not trained on Jev outputs.

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