📱 Run it on your phone or a GPU-less PC → POCKET · 🚀 Try it live (CPU chat)
VIDRAFT's on-device family: a 35B model that runs on iPhone and on CPU with no GPU — stock llama.cpp, no fork.
Darwin-28B-Opus — Qwen3.6-27B × Opus-Distilled Evolutionary Merge
Qwen3.6-27B dense · 27.6B parameters · Hybrid Linear/Full Attention · BF16 · Thinking Mode · Apache 2.0
Darwin V7 evolutionary merge: Father × Opus-distilled Mother → 88.89% on GPQA Diamond (3-stage adaptive evaluation)
Abstract
Darwin-28B-Opus is the first reasoning model of the Darwin series built on the Qwen3.6 generation backbone. Produced by the Darwin V7 evolutionary breeding engine from two publicly available parents, it combines the strong bilingual reasoning of Qwen3.6-27B with Claude Opus 4-style chain-of-thought distilled behaviour.
On the GPQA Diamond graduate-level reasoning benchmark (198 PhD-level questions), Darwin-28B-Opus scores 88.89 % under the standard 3-stage adaptive evaluation, slightly edging out its larger MoE sibling Darwin-36B-Opus (88.4 %) and clearly surpassing its Qwen3.5-generation counterpart Darwin-27B-Opus (86.9 %).
🧬 Model Lineage
| Role | Model | Role in the Merge |
|---|
| Father (父) | Qwen/Qwen3.6-27B | Qwen3.6 generation dense backbone with hybrid linear/full attention. |
| Mother (母) | rico03/Qwen3.6-27B-Claude-Opus-Reasoning-Distilled | Claude Opus reasoning-distilled variant of the same backbone (Jackrong-style distillation, 14 k traces). |
| Offspring | Darwin-28B-Opus (this model) | Darwin V7 evolutionary merge; Qwen3.6 architecture retained, Opus reasoning style inherited. |
Why 28B? The 28B label denotes the Qwen3.6-generation member of the Darwin lineup (+1 over the Qwen3.5-era Darwin-27B-Opus).
The actual parameter count is 27.6 B, and the architecture exactly follows Qwen3.6-27B.
⚙️ Technical Specifications
| Component | Value |
|---|
| Architecture | Qwen3_5ForConditionalGeneration (Qwen3.6 generation, hybrid linear + full attention) |
| Parameters | 27.6 B (BF16) |
| Hidden size | 5 120 |
| Intermediate size | 17 408 |
| Head dim | 256 |
| Layers | 64 (3 linear : 1 full attention, full_attention_interval = 4) |
| Precision | bfloat16 |
| Context length | Inherited from base (long-chain reasoning supported) |
| License | Apache 2.0 |
🏆 Benchmark — GPQA Diamond (198 questions)
Darwin-28B-Opus is evaluated under our standard 3-stage adaptive evaluation protocol, identical to the protocol used across the Darwin series.
| Stage | Decoding Protocol | Cost | Accuracy |
|---|
| Stage 1 | Single-shot greedy baseline | 1× | 74.75 % (148 / 198) |
| Stage 2 | Majority vote ×8 at temperature 0.7 on Stage-1 wrongs | 8× | 83.84 % (166 / 198) |
| Stage 3 | Adaptive ensemble refinement (close-tie tiebreaker + iterative MTI on residual hard questions) | ≈ 20× | 🥇 88.89 % (176 / 198) |
Key performance indicators:
- Stage 1 → Stage 3: +14.14 %p through adaptive protocol
- vs Darwin-27B-Opus (86.9 %): +1.99 %p
- vs Darwin-36B-Opus (88.4 %): +0.49 %p
- vs Darwin-31B-Opus (85.9 %): +2.99 %p
🚀 Usage
Standard inference (Stage 1 baseline)
1from transformers import AutoTokenizer, AutoModelForCausalLM
2import torch
3
4tok = AutoTokenizer.from_pretrained(
5 "FINAL-Bench/Darwin-28B-Opus",
6 trust_remote_code=True,
7)
8model = AutoModelForCausalLM.from_pretrained(
9 "FINAL-Bench/Darwin-28B-Opus",
10 torch_dtype=torch.bfloat16,
11 device_map="auto",
12 trust_remote_code=True,
13)
14
15messages = [
16 {"role": "user",
17 "content": "Solve: If f(x) = x³ − 3x + 2, find all critical points and classify them."}
18]
19text = tok.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
20inputs = tok(text, return_tensors="pt").to(model.device)
21outputs = model.generate(**inputs, max_new_tokens=2048, do_sample=False)
22print(tok.decode(outputs[0][inputs.input_ids.shape[-1]:], skip_special_tokens=True))
Enhanced accuracy (Stage 2-3 adaptive)
For leaderboard-grade accuracy, combine:
- Stage 1 greedy baseline,
- Stage 2 maj@8 temperature sampling on low-confidence answers,
- Stage 3 adaptive refinement on still-disputed answers.
Reference implementation is provided in the Darwin-series evaluation harness.
🎯 Recommended Use-Cases
- Graduate-level STEM reasoning (GPQA / science qualifying exams)
- Mathematical problem solving (MATH, AIME-style problems)
- Code generation and debugging (HumanEval, MBPP)
- Complex multi-step chain-of-thought tasks
- Bilingual reasoning (strong English + Korean; also Chinese / Japanese)
⚠️ Limitations
- At 27.6 B parameters in bfloat16, full inference requires ≈ 55 GB of VRAM (e.g., a single A100-80GB or B200).
- Optimised for English first, with secondary support for Korean, Chinese, and Japanese.
- Deep Opus-style reasoning traces tend to be verbose — control with
max_new_tokens as needed.
📚 Citation
1@misc{darwin28b_opus_2026,
2 title = {Darwin-28B-Opus: Evolutionary Merging of Qwen3.6-27B with Claude-Opus-Distilled Reasoning},
3 author = {FINAL-Bench / Darwin Research Team},
4 year = {2026},
5 howpublished = {\url{https://huggingface.co/FINAL-Bench/Darwin-28B-Opus}},
6 note = {Darwin V7 · Mother-centric Ratio Interpolation merge · 88.89 % GPQA Diamond (3-stage)}
7}
🔗 Related Darwin Models
- Darwin-36B-Opus — MoE 36B, Qwen3.6-35B-A3B × Opus distilled, GPQA 88.4 %
- Darwin-31B-Opus — 31B dense, multilingual-strong reasoning, GPQA 85.9 %
- Darwin-27B-Opus — 27B dense (Qwen3.5 generation), GPQA 86.9 %
- Darwin-9B-NEG — 9B with Native Entropy Gating, GPQA 84.3 %
- Darwin-9B-Opus — the Qwen3.5-9B Darwin member
- Darwin-4B-Genesis — smallest Darwin member
📱 Related — POCKET (run a 35B model on-device)
Want Darwin-class reasoning without a datacenter GPU? POCKET is VIDRAFT's on-device family — a 35B model that runs on a phone and on a GPU-less PC using stock llama.cpp (no fork, no CUDA, no cloud). On a free CPU it generates ~3.4× faster than Bonsai, the most-downloaded on-device model (2M+), at matched quality (HellaSwag 61.0 % vs 60.0 %, a statistical tie).
This model is introduced in
Darwin Family.
Darwin V7 · Qwen3.6 generation flagship · Sealed 2026-04-25 · FINAL-Bench
-blue?style=for-the-badge){kind=icon}
-purple?style=for-the-badge){kind=icon}
-blue?style=for-the-badge){kind=icon}
-blue?style=for-the-badge){kind=icon}
-blue?style=for-the-badge){kind=icon}
