| --- |
| license: apache-2.0 |
| inference: false |
| tags: |
| - dflash2 |
| - draft-only |
| - speculative-decoding |
| - block-diffusion |
| - draft-model |
| - qwen3.8-27b-target |
| - mlx |
| --- |
| |
| # DFlash2 |
|
|
| This repository contains the promoted DFlash2 draft head used with |
| [`Qwen/Qwen3.8-27B`](https://huggingface.co/Qwen/Qwen3.8-27B). It is not a |
| fine-tune of the full Qwen target and must not be loaded as a standalone |
| language model. It has no tokenizer and no target weights: a compatible |
| DFlash2 runtime loads this head alongside the Qwen verifier. |
|
|
| The Hub base-model tree is intentionally omitted. A conventional |
| "Qwen finetune" label would misrepresent the artifact: only the small |
| speculative draft head is changed, while target-controlled output remains the |
| authority. |
|
|
| The head descends from the public Qwen3.8-27B DFlash2 draft model. It was |
| adapted with target-verified cycles from the incumbent legacy corpus and a |
| session-grouped Fable agentic corpus. The final checkpoint combines a |
| generation-2 Fable adaptation at strength `0.0625` with a generation-3 |
| combined-domain adaptation at strength `0.1875`. |
|
|
| No trace dataset, prompt file, capture cycle, selector tensor, or W&B log is |
| included in this repository. Only the final draft checkpoint, configuration, |
| blend metadata, and evaluation summary are published. |
|
|
| ## Acceptance results |
|
|
| All acceptance runs used greedy target-controlled generation on one Apple M4 |
| Max through DFlash MLX. The target was the calibrated Qwen3.8-27B MXFP4 |
| runtime. `Draft quantization` was disabled for this head. |
|
|
| | Paired gate | Incumbent | This head | Mean delta | Wins / ties / losses | |
| | --- | ---: | ---: | ---: | ---: | |
| | Legacy 24-prompt corpus | `0.6712239583` | `0.6718750000` | `+0.0006510417` | 5 / 14 / 5 | |
| | Fable 25-prompt held-out | `0.6471875000` | `0.6492187500` | `+0.0020312500` | 11 / 5 / 9 | |
|
|
| The Fable live-gate prompts were excluded from the generation-2 and combined |
| training splits. The legacy corpus had already been used to train the |
| incumbent, so it remained in the combined training capture for a paired |
| comparison. |
|
|
| ## Exact parity |
|
|
| The exact 256-token baseline-versus-DFlash smoke gate passed: |
|
|
| - `token_match`: `true` |
| - smoke acceptance: `0.7109375` |
| - diagnostic baseline throughput: `21.9615` tok/s |
| - diagnostic DFlash throughput: `33.5111` tok/s |
|
|
| Throughput is diagnostic only. Thermal pressure and co-tenant machine load |
| were not controlled. |
|
|
| ## Training summary |
|
|
| - combined capture: 11,273 target-verified cycles |
| - prompt groups: 127 |
| - legacy contribution: 1,981 cycles from 24 prompts |
| - Fable contribution: 9,292 cycles from 103 training prompts |
| - excluded Fable live gate: 25 prompts |
| - teacher signal: target top-64 logits and greedy target tokens |
| - final full-run held-out prefix accuracy: `0.7932212528` |
| - final full-run held-out top-1 accuracy: `0.8714877986` |
|
|
| The capture teacher was the calibrated MXFP4 Qwen3.8-27B target runtime, not |
| the pinned BF16 Qwen3.8-27B checkpoint. This precision choice is part of the |
| training provenance. |
|
|
| ## Checkpoint integrity |
|
|
| - `model.safetensors` SHA-256: |
| `c90e0fc65dddbe4107b1b417d771c3be188c87197e89cf4b14415f56abc866f0` |
| - `config.json` SHA-256: |
| `873e3556509b0da06e29654ba00d4944888d4b5e8a33afde25f7eb27d321e980` |
| - `blend.json` SHA-256: |
| `e53a6bb5e890d7e3368053302189766c3ef68d2eb7887152ece1ea9eac4f64d5` |
|
|
| ## Intended use and limits |
|
|
| This artifact is for lossless speculative decoding research with a compatible |
| DFlash2 implementation. Acceptance metrics do not establish broad task quality, |
| natural-EOS behavior, multilingual performance, long-context performance, or a |
| controlled thermal throughput win. The Fable held-out prompts come from the |
| same eval shard as the Fable training prompts, so that gate does not prove |
| out-of-domain generalization. |
|
|
