How to ask it
The fine-tune binds these exact strings. One noul question (probability that the statement holds):
{"type": "noul", "instructions": "Does the code correctly and completely implement the request, so it would pass a thorough hidden test suite including edge cases? Judge from the request, the code and the checks shown."}
State (an object; Kev renders it as key: value lines):
{"request": "<the task, verbatim>", "code": "<the model's code>", "checks": {"compiles": true, "defines_requested_function": true, "passes_examples_in_request": true, "generated_edge_case_tests": "7 of 8 passed", "note": "edge-case tests were written by a small model from the request alone; some may be wrong"}}
generated_edge_case_tests comes from a small model writing ~8 asserts from the request only, then running them.
Serve with Kev's runtime (python -m kev.serve --run jtatman/kev-0.8b-code-verify-v1, a TypeSafe /v1/systemone endpoint) or
kev.predictors.LocalPredictor. The checkpoint carries its fitted temperature.
Results
Unseen coder (llama-3.1-8b-instruct, never in training): 488 attempts, pass rate 0.57. "Kept local @X% err" = share of attempts a router can accept, highest score first, with at most X% of
them wrong. evidence score = (request examples passed + generated-assert pass rate) / 2.
Table with columns: score, AUROC, Brier, ECE, kept local @2% err, @5%, @10%| score | AUROC | Brier | ECE | kept local @2% err | @5% | @10% |
|---|
| baseline kev | 0.935 | 0.096 | 0.12 | 0.23 | 0.28 | 0.48 |
| fine-tuned kev | 0.959 | 0.064 | 0.05 | 0.23 | 0.40 | 0.63 |
Development (coders seen in training, tasks not seen):
Table with columns: score, AUROC, Brier, ECE, kept local @2% err, @5%, @10%| score | AUROC | Brier | ECE | kept local @2% err | @5% | @10% |
|---|
| baseline kev | 0.925 | 0.029 | 0.05 | 0.73 | 0.89 | 0.95 |
| fine-tuned kev | 0.941 | 0.025 | 0.03 | 0.80 | 0.89 | 0.95 |
Numbers are on small sets; see the project repo for task-bootstrap confidence intervals.
Recommended use
Average this model's probability with the execution evidence score, and tune the accept threshold per cheap-tier
coder on a few hundred of that coder's execution-labelled attempts: a fixed threshold's error rate depends on how
often the coder fails.
Training
- Init:
jaredpalmer/kev-0.8b@9a45d25 (LoRA r=16 + pointer head, base Qwen/Qwen3.5-0.8B-Base), Kev's own trainer (kev.train, commit f2bb629d).
- Data: 1416 execution-labelled records (task-grouped split;
llama-3.1-8b held out) + 2000 public
decision-v7 replay records against forgetting.
- One epoch, lr 2e-05, batch 4 x accum 2, gradient checkpointing, bf16 autocast,
state limit 1664 tokens.
- Temperature fitted on a held-out calibration split (min NLL).
- Hardware: one NVIDIA L4 (Google Colab).
Training data provenance
Code attempts whose correctness this model learned to judge (labels from executing hidden tests):
Table with columns: source, model, license, training rows| source | model | license | training rows |
|---|
| or:mistral-small-3.2-24b | mistralai/Mistral-Small-3.2-24B-Instruct-2506 | Apache-2.0 | 297 |
| or:qwen3-235b-a22b | Qwen/Qwen3-235B-A22B-Instruct-2507 | Apache-2.0 | 292 |
| or:qwen3-coder-30b-a3b | Qwen/Qwen3-Coder-30B-A3B-Instruct | Apache-2.0 | 238 |
| qwen2.5-coder:3b | Qwen/Qwen2.5-Coder-3B-Instruct | Qwen Research License |
Built with Qwen. Training data includes outputs of Qwen2.5-Coder-3B-Instruct, used under the Qwen Research
License Agreement (section 4b). The held-out test coder (Llama 3.1 8B Instruct) was never used for training.
Limitations
- Python function-level tasks only (HumanEvalPack); other languages, repos and multi-file changes are untested.
- The coder pool is 8-10 models of 3B-235B parameters; accept thresholds do not transfer across coders.
- Trained on this question and state layout; other phrasings work less well.
Credits
Kev by Jared Palmer (jaredpalmer/kev, Apache-2.0); Qwen3.5 base (Apache-2.0);
HumanEvalPack (bigcode). Project: https://github.com/jtatman/kev-code-verify