lishunyang
69bcc6416d
Adds Lance (bytedance-research/Lance), a 3B unified AR+diffusion multimodal model on a Qwen2.5-VL backbone. Lance is BAGEL-lineage: it reuses vLLM-Omni's BAGEL Mixture-of-Transformers core verbatim and specializes only the ViT (Qwen2.5-VL vision), the VAE (Wan2.2) and the checkpoint layout. All six single-stage Lance modalities verified end-to-end on 1x B300: t2i, t2v, image_edit, video_edit, x2t_image (image understanding) and x2t_video (video understanding). 3-D mRoPE is wired through BagelRotaryEmbedding for the x2t / video / edit paths. Includes the upstream gap-analysis quality fixes (task-specific system prompts, full Qwen chat template, upstream inference defaults and aspect-ratio buckets). Ships an offline example (examples/offline_inference/lance/), an OpenAI-compatible online-serving example (examples/online_serving/lance/) and an e2e test (tests/e2e/online_serving/test_lance.py). See LANCE_PR.md for the architecture rationale, per-modality status and the two remaining follow-ups (two-stage AR+DiT, video_edit polish). Closes #3697. Signed-off-by: lishunyang <lishunyang03@gmail.com>
Lance — online serving
OpenAI-compatible chat completions API for Lance, served by vllm-omni.
Start the server
bash examples/online_serving/lance/run_server.sh
# or, with overrides
MODEL=bytedance-research/Lance \
DEPLOY_CONFIG=vllm_omni/deploy/lance.yaml \
PORT=8091 \
bash examples/online_serving/lance/run_server.sh
The default deploy config is the single-stage lance.yaml; for video_edit
or text2video workloads, point DEPLOY_CONFIG at a video-checkpoint
config (or pass --model bytedance-research/Lance/Lance_3B_Video to
run_server.sh).
Send a request
# text-to-image
python examples/online_serving/lance/openai_chat_client.py \
--prompt "A cute corgi astronaut on the moon, cinematic" \
--modality text2img \
--output corgi.png
# image edit
python examples/online_serving/lance/openai_chat_client.py \
--prompt "Convert this into a vibrant cartoon-style illustration" \
--modality img2img \
--image-url path/to/photo.png \
--output edited.png
The client is shared with BAGEL — same OpenAI message format, same
modalities and num_inference_steps / seed / height /
width knobs.