Changelog
v1.1 — broader general judgment (current)
Same architecture and inference contract as v1.0; retrained on an expanded blend (DialAM-2024 argument
edges, NLI, PAWS, e-CARE/COPA causal, dedup hard-negatives, completeness, and synthetic directional
data, on top of v1.0). Still one model, programmed by a sentence — no per-task fine-tuning.
New: directional & typed-edge judgment — supersession ("B replaces A"), depends-on,
supports / contradicts. Bosun now reads the ordered pair for asymmetric relations, not just
symmetric similarity.
Generality on held-out public benchmarks (one instruction each), vs a frontier LLM on the same items:
Table with columns: benchmark, Bosun-4B v1.1, gemini-3.1-flash-lite, similarity baseline, fine-tuned specialist| benchmark | Bosun-4B v1.1 | gemini-3.1-flash-lite | similarity baseline | fine-tuned specialist |
|---|
| PAWS (adversarial paraphrase) | 0.91 | 0.81 | ~chance (0.53 AUROC) | ~0.95 (DeBERTa) |
| e-CARE (causal direction) | 0.85 | 0.86 | 0.60 | ~0.75 (paper) |
| ANLI (adversarial NLI) | 0.57 | 0.74 | 0.33 | ~0.69 |
Bosun-4B beats gemini-3.1-flash-lite on PAWS, ties it on e-CARE, and trails on ANLI — while
crushing it on steerable judgment (WarrantBench 0.945 vs 0.575). Edge curation (DialAM-2024): recall
0.71, beating Sonnet on recall + precision.
No regression: FollowIR flat vs v1.0; WarrantBench steerability 0.885 → 0.945.
v1.0 — launch
Symmetric programmable judge. WarrantBench steerability 0.885; FollowIR state-of-the-art (+17.9 p-MRR).
Inference contract
Native Qwen3-Reranker template; read the last-token logits:
<Instruct>: <your rule, e.g. "Connected only if the two findings share a specific named entity."><Query>: These two findings share the specified relationship.<Document>: FINDING A:\n<text_a>\n\nFINDING B:\n<text_b>
score = sigmoid(logits[yes_id] - logits[no_id]) at the final position (logits_to_keep=1). The exact
yes_id / no_id / template prefix+suffix and max_len are in serving.json.
import torchfrom transformers import AutoTokenizer, AutoModelForCausalLMfrom peft import PeftModel repo = "Hanno-Labs/bosun-4b"cfg = ... # serving.json from this repotok = AutoTokenizer.from_pretrained(repo, subfolder="tokenizer", padding_side="left")base = AutoModelForCausalLM.from_pretrained(cfg["base_model"], torch_dtype=torch.bfloat16, attn_implementation="sdpa", trust_remote_code=True)model = PeftModel.from_pretrained(base, repo).merge_and_unload().eval().cuda()# build ids = prefix + <Instruct/Query/Document> + suffix, then:# lg = model(input_ids, attention_mask, logits_to_keep=1).logits[:, -1, :]# p = torch.sigmoid(lg[:, cfg["yes_id"]] - lg[:, cfg["no_id"]])
Run locally (GGUF / llama.cpp)
CPU / Apple-Silicon / edge builds (f16, Q8_0, Q4_K_M — all calibration-safe at 4B) live at
Hanno-Labs/bosun-4b-GGUF.
⚠️ Do not use llama.cpp's --rerank mode — it silently discards the <Instruct> and returns
degenerate, instruction-blind scores. Use the completion + logits path documented in that repo
(validated per-pair against this model's transformers reference — Q8_0 within ~0.001).
Results
Bosun-4B is state-of-the-art on FollowIR (public instruction-following retrieval), averaging
+17.9 p-MRR on the full pool — it changes its judgments correctly when the instruction changes,
where most retrievers move the wrong way. On a capped pool it matches gemini-3.1-flash-lite
head-to-head (12.0 = 12.0) at a fraction of the cost.
WarrantBench (Hanno-Labs/warrantbench):
follows arbitrary rules and their negations, and flips correctly on steerability triples. The 4B
capacity closes the hardest-slice gap to the frontier LLM that the 0.6B leaves open.
Files
Table with columns: file, what| file | what |
|---|
adapter_model.safetensors, adapter_config.json | the LoRA adapter (load with PEFT over the base) |
serving.json | inference contract: template + yes_id/no_id + max_len |
tokenizer/ | Qwen tokenizer (left-padding) |
Links
From Hanno Labs.