---
license: other
license_name: stabilityai-ai-community
license_link: https://huggingface.co/stabilityai/stable-diffusion-3.5-medium/blob/main/LICENSE.md
base_model: stabilityai/stable-diffusion-3.5-medium
pipeline_tag: text-to-image
library_name: diffusers
tags:
- lora
- reinforcement-learning
- few-step
- flow-map
- fewsteprl
---

# FewStepRL — SD3.5-Medium checkpoints

Released checkpoints of **FewStepRL: Fine-tuning Few-step Diffusion Models with Reinforcement Learning**
(image experiments, 4-step SD3.5-Medium flow map).

[Paper (arXiv:2611.08240)](https://arxiv.org/abs/2611.08240) ·
[Code](https://github.com/EDAPINENUT/fewsteprl-sd35) ·
[Project page](https://edapinenut.github.io/fewsteprl.page/) ·
[Video checkpoints (Wan2.1)](https://huggingface.co/Delcher/fewsteprl-wan21)

## Contents

```
<trial>/
  config.yaml                          # the config the run saved
  checkpoint-<step>/generator_ema.pt   # EMA generator: Stage-3 LoRA + delta_embedder
aux_vel/{mix,ocr}/
  config.yaml
  aux_v_transformer/                   # auxiliary v-predictor (diffusers SD3Transformer2DModel)
SHA256SUMS
```

| trial | trainer | reward | step |
|---|---|---|---|
| meanflownft_mix | `meanflow_nft` | mixed | 400 |
| dmdnft_mix | `dmdnft_rl` | mixed | 400 |
| dmdawm_mix | `dmdawm_rl` | mixed | 400 |
| fewstepgrpo_mix | `meanflowgrpo_rl` | mixed | 300 |
| meanflowawm_mix | `meanflowawm_rl` | mixed | 400 |
| meanflowopsd_mix | `meanflowopsd_rl` | mixed | 400 |
| reflmx_mix | `meanflowrefl_rl` | mixed | 400 |
| flowgrpo_mix / awm_mix / nft_mix | original objectives (baselines) | mixed | 400 |
| meanflownft_ocr | `meanflow_nft` | OCR | 200 |
| dmdnft_ocr | `dmdnft_rl` | OCR | 200 |
| dmdawm_ocr | `dmdawm_rl` | OCR | 400 |
| fewstepgrpo_ocr | `meanflowgrpo_rl` | OCR | 200 |
| meanflowawm_ocr | `meanflowawm_rl` | OCR | 400 |

Scores and per-checkpoint notes:
[checkpoints/README.md](https://github.com/EDAPINENUT/fewsteprl-sd35/blob/main/checkpoints/README.md).

## Usage

Download the weights into the `checkpoints/` directory of the code repository:

```bash
git clone https://github.com/EDAPINENUT/fewsteprl-sd35 && cd fewsteprl-sd35
bash download_scripts/download_assets.sh          # SD3.5-Medium, AnyFlow Stage-1/2 LoRAs, reward models
hf download Delcher/fewsteprl-sd35 --local-dir checkpoints --include "*.pt" "*.safetensors"
cd checkpoints && shasum -a 256 -c SHA256SUMS && cd ..
```

`generator_ema.pt` is applied **on top of** SD3.5-Medium + the AnyFlow Stage-1 and Stage-2 LoRAs, never alone:

```bash
bash scripts/eval/sample.sh meanflownft_mix       # 4-step sampling with a released checkpoint
bash scripts/eval/eval_ckpt.sh meanflownft_mix 8  # sample + score
```

The `aux_vel/{mix,ocr}` v-predictors are only needed to train the `dmd*` trials.

## License

The weights are derivatives of SD3.5-Medium and are subject to the
[Stability AI Community License](https://huggingface.co/stabilityai/stable-diffusion-3.5-medium/blob/main/LICENSE.md).

## Citation

```bibtex
@article{lin2026fewsteprl,
  title   = {FewStepRL: Fine-tuning Few-step Diffusion Models with Reinforcement Learning},
  author  = {Lin, Haitao and Ren, Minsi and Li, Yang and Ge, Xingtong and
             Hu, Zheyuan and Hu, Peiyan and Wu, Tailin},
  journal = {arXiv preprint arXiv:2611.08240},
  year    = {2026}
}
```