---
license: apache-2.0
base_model: samscrack/Qwopus3.6-27B-solidity-sft-stage1B
language:
  - en
library_name: peft
tags:
  - solidity
  - smart-contracts
  - security-audit
  - long-cot
  - reasoning
  - chain-of-thought
  - lora
  - qlora
  - peft
  - blockchain
  - ethereum
  - sft
datasets:
  - samscrack/solidity-audit-cot
pipeline_tag: text-generation
inference: false
---

# Qwopus3.6-27B-solidity-audit-stage2

> ⚠️ **Intermediate checkpoint — Stage 2 of 5.** This is the audit / Long-CoT reasoning LoRA, layered on top of the Stage 1B SFT base. **Not yet RFT-tuned** — Stage 3 (rejection-sampling fine-tuning against `forge test`) and the optional Stage 4 (GSPO RL with executor reward) come next.

A LoRA r=16 adapter on top of `Qwopus3.6-27B-solidity-sft1B-merged` (Stage 1B merged into bf16 base) that teaches the model to:
- read a Solidity contract end-to-end
- emit a long chain-of-thought (8-15 substantive paragraphs) in `<think>...</think>`
- output a structured finding (severity, category, location, description, impact, fix, confidence)

## Pipeline context

| # | Stage | Status | Output |
|---|---|---|---|
| 0 | Continued pretrain (DoRA on Solidity corpus) | ✅ done | [`Qwopus3.6-27B-solidity-cpt-stageA`](https://huggingface.co/samscrack/Qwopus3.6-27B-solidity-cpt-stageA) |
| 1 | SFT (instruction): spec → contract | ✅ done | [`Qwopus3.6-27B-solidity-sft-stage1B`](https://huggingface.co/samscrack/Qwopus3.6-27B-solidity-sft-stage1B) |
| **2** | **SFT (audit / Long-CoT reasoning)** | **✅ done — this repo** | this repo |
| 3 | RFT (rejection-sampling FT against `forge test`) | ⬜ planned | TBD |
| 4 | GSPO (sequence-level RL with executor reward) | ⬜ optional | TBD |

## Training data

- **Corpus**: [`samscrack/solidity-audit-cot`](https://huggingface.co/datasets/samscrack/solidity-audit-cot) — Long-CoT audit traces generated by Claude Opus 4.7 (adaptive thinking, xhigh effort) over real Solidity contracts.
- **Strict-quality cleaned**: 7,707 rows. **8K-friendly subset for this stage**: 6,140 rows (filtered to ≤30,000 chars total → fits in 8K ctx). The remaining 1,567 long-tail rows are preserved at [`audit_cot_clean_long_tailed.jsonl`] for a future longer-context Stage 2 re-run.
- **After ctx-filter at training time**: 6,106 rows (34 marginal rows dropped).
- **Severity distribution (full clean corpus)**: 33% high · 25% medium · 14% low · 14% informational · 14% none. The `none` rows are deliberate — they teach the model not to fabricate vulnerabilities.

Each row's user turn is the contract code with an "Audit this contract" instruction. The assistant turn is `<think>{12 reasoning paragraphs joined}</think>` followed by a structured finding rendered as markdown.

## Recipe (Stage 2 specifics, per SOTA-plan §2)

- **LoRA**: r=16, α=16, dropout=0 (smaller than Stage 1B's r=64 — layered on, not replacing)
- **Target modules**: `q_proj, k_proj, v_proj, o_proj, gate_proj, up_proj, down_proj, out_proj`
- **Trainable parameters**: 88,342,528 (~0.60% of effective 14.8B param count)
- **Quantization**: base loaded in 4-bit (BnB NF4); adapter weights bf16
- **Effective batch size**: 72 (4 per device × 9 grad accum × 2 GPUs)
- **Sequence length**: 8,192
- **Optimizer**: 8-bit AdamW, weight decay 0.001
- **Learning rate**: 1e-4 (half of Stage 1B's 2e-4 — finer adjustment on top of trained base)
- **Epochs**: 1
- **Total steps**: 85
- **Chat template**: `qwen3-thinking` (with `<think>` filled by real Opus-derived reasoning)
- **Loss masking**: `train_on_responses_only` (loss only on assistant tokens after `<|im_start|>assistant\n<think>`)

## Training metrics

- **Wall time**: 3h 48m
- **Train loss**: 1.21 (start) → ~0.99 (min) → 1.026 (final under linear decay)
- **Hardware**: 2× NVIDIA RTX PRO 6000 Blackwell Workstation Edition (96 GB each)
- **Distributed**: DDP via `torchrun --nproc-per-node=2`
- **Framework**: [Unsloth](https://github.com/unslothai/unsloth) 2026.4.7 with TRL 0.22.2

## Usage

```python
from peft import PeftModel
from transformers import AutoModelForCausalLM, AutoTokenizer

# Load the Stage-1B-merged base, then layer the Stage 2 LoRA
base = AutoModelForCausalLM.from_pretrained(
    "samscrack/Qwopus3.6-27B-solidity-sft-stage1B",  # merge with the CPT base first locally
    torch_dtype="bfloat16", device_map="auto",
)
model = PeftModel.from_pretrained(base, "samscrack/Qwopus3.6-27B-solidity-audit-stage2")
tokenizer = AutoTokenizer.from_pretrained("samscrack/Qwopus3.6-27B-solidity-audit-stage2")

contract = open("MyContract.sol").read()
messages = [{"role": "user", "content":
    "Audit the following Solidity contract for security issues. Identify the most "
    "impactful vulnerability (or 'none' if the contract is clean), reason step-by-step "
    "about your analysis, then output a structured finding with severity, category, "
    "location, description, impact, and a concrete fix.\n\n"
    f"```solidity\n{contract}\n```"}]
prompt = tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
inputs = tokenizer(prompt, return_tensors="pt").to(model.device)
out = model.generate(**inputs, max_new_tokens=4096, do_sample=False)
print(tokenizer.decode(out[0], skip_special_tokens=False))
```

The output will contain a `<think>` block with multi-paragraph reasoning followed by a markdown audit report.

## Limitations

- **Single-finding output by design.** Each response identifies the one most-impactful issue. Multi-finding audits would require either prompting it to "find all issues" or running it with different temperatures and aggregating.
- **Synthetic teacher.** Reasoning style and breadth reflect Claude Opus 4.7's idiom. The model has been pushed in that direction; output quality is bounded by Opus's audit ceiling.
- **No `forge test` validation in the loss.** This stage uses next-token cross-entropy on Opus traces. Stage 3 RFT introduces test-pass as a reward signal — that's where functional correctness gets enforced.
- **Long contracts truncated.** Training set was filtered to contracts that fit in 8K tokens. Contracts >~7,500 tokens may produce shorter or less coherent reasoning at inference time.
- **Solidity ≥ 0.7 bias** (inherited from Stage 1B's strict pragma filter).
- **Findings can be wrong.** Like any synthetic-teacher SFT, this model can produce confident-sounding false positives (flagging non-bugs) or miss real issues. Use as a triage assistant, not a substitute for human audit review.

## Related artifacts

- **Stage 0 CPT**: [`samscrack/Qwopus3.6-27B-solidity-cpt-stageA`](https://huggingface.co/samscrack/Qwopus3.6-27B-solidity-cpt-stageA)
- **Stage 1 SFT**: [`samscrack/Qwopus3.6-27B-solidity-sft-stage1B`](https://huggingface.co/samscrack/Qwopus3.6-27B-solidity-sft-stage1B)
- **Training data**: [`samscrack/solidity-audit-cot`](https://huggingface.co/datasets/samscrack/solidity-audit-cot)
- **Eval set (held-out, must not train on)**: [`samscrack/solidity-eval-2026`](https://huggingface.co/datasets/samscrack/solidity-eval-2026)

## Citation

```bibtex
@misc{qwopus3-6-27b-solidity-audit-stage2-2026,
  author       = {samscrack},
  title        = {Qwopus3.6-27B-solidity-audit-stage2: Stage 2 audit/Long-CoT LoRA},
  year         = {2026},
  publisher    = {Hugging Face},
  howpublished = {\url{https://huggingface.co/samscrack/Qwopus3.6-27B-solidity-audit-stage2}},
}
```