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lerobot/docs/source/lingbot_va.mdx
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Pepijn e275ea3960 LingBot-VA: video-action world model (#3731)
* feat(policies): add LingBot-VA autoregressive video-action world model

Port the LingBot-VA policy (Wan2.2 dual-stream video+action world model) into
LeRobot, following the EO-1 / VLA-JEPA conventions. Covers inference, checkpoint
conversion, and predicted-video saving (training is deferred to a follow-up PR).

- Vendored Wan transformer/attention/flex/VAE/scheduler modules (key names preserved
  for near-identity conversion); torch SDPA default, flashattn/flex lazy-guarded.
- LingBotVAConfig (registered "lingbot_va") + processor with fixed-quantile action
  unnormalization; full dual-stream sampling loop with CFG, two flow-matching
  schedulers and KV cache, mapped onto select_action with observed-keyframe feedback.
- convert_lingbot_va_checkpoints.py (libero/robotwin variants): bundles the ~5B
  transformer, lazy-pulls the frozen VAE+UMT5 from the source repo.
- Predicted-video plumbing in lerobot_eval (predicted_frames_callback; opt-in via
  --policy.save_predicted_video) and ConstantWithWarmupSchedulerConfig.
- pyproject: widen diffusers-dep to <0.37, add lingbot_va + imageio-dep extras,
  add lingbot_va and (missing) eo1 to `all`.
- Factory + policies/__init__ wiring, docs page + toctree, and tests.

Note: the LIBERO success-rate correctness gate must be validated on a CUDA GPU
with the converted checkpoint.

* feat(lingbot_va): RoboTwin eef-pose eval, single-file model, Hub checkpoints

Make the LingBot-VA port runnable on both LIBERO and RoboTwin and clean up the
package to LeRobot conventions.

- Consolidate all vendored Wan2.2 model code (transformer, attention, VAE helpers,
  flow-matching scheduler, grid utils, flex-attention) into a single
  modeling_lingbot_va.py; remove the separate wan_*/schedulers modules.
- Move the fixed action (un)normalization quantiles out of the config and into the
  post-processor (LIBERO 7-DoF + RoboTwin 16-d eef); remove the conversion script in
  favour of ready-to-use LeRobot-format checkpoints on the Hub.
- Fixes found via on-sim validation: undo LIBERO's 180-degree image flip
  (image_hflip), encode obs as a multi-frame streaming-VAE clip, reset the streaming
  VAE cache between episodes, run the transformer in config.dtype, lazy-load frozen
  VAE/UMT5 by subfolder with the text encoder on CPU.
- RoboTwin: add an end-effector-pose action mode to RoboTwinEnv (16-d per-arm
  xyz+quat+gripper deltas composed onto the initial eef pose, executed via CuRobo IK)
  and the robotwin_tshape latent layout (full-res head + half-res wrists via a second
  streaming VAE) with the upstream RoboTwin action quantiles + camera mapping.
- Predicted-video saving works for both benchmarks; docs + tests updated.

* feat(lingbot_va): implement training / fine-tuning (flow-matching loss)

- Implement LingBotVAPolicy.forward(): dual-stream flow-matching training loss
  (latent + action, timestep-weighted, action-masked) ported from upstream train.py;
  VAE-encodes camera clips, UMT5-encodes the task, noises both streams, runs the
  block-causal flex-attention training pass (forward_train).
- training_loss_from_streams() core + _build_training_streams() data prep (action
  scatter into the 30-d space, multi-frame VAE encode incl. robotwin_tshape).
- get_optim_params returns only trainable transformer params (LoRA/PEFT friendly);
  VAE/UMT5 stay frozen. Training needs attn_mode='flex'.
- Add a tiny-config single-training-step test (forward->loss->backward->AdamW) and a
  Training/fine-tuning section in the docs.

* fix(lingbot_va): CI quality gate + fast-test collection

- Add tests/policies/lingbot_va/__init__.py so the test files don't clash by basename
  with tests/policies/vla_jepa/* under pytest's default import mode (fast-test collection error).
- Fix vendored typos flagged by the typos hook (pach_scale->patch_scale, total_tolen->
  total_token_len, stablized->stabilized) and a mypy union-attr in RoboTwinEnv._read_eef_pose.
- Apply Prettier formatting to docs/source/lingbot_va.mdx.

* docs(lingbot_va): document EEF action-channel schema + camera order

* Update lingbot_va.mdx

Signed-off-by: Pepijn <138571049+pkooij@users.noreply.github.com>

* Update pyproject.toml

Signed-off-by: Pepijn <138571049+pkooij@users.noreply.github.com>

* Update pyproject.toml

Signed-off-by: Pepijn <138571049+pkooij@users.noreply.github.com>

* refactor(lingbot_va): drop hardcoded action quantiles; source from checkpoint

The LIBERO/RoboTwin action (un)normalization quantiles were hardcoded as module
constants in processor_lingbot_va.py. They are already serialized into each
checkpoint's policy_postprocessor.json (via LingBotVAActionUnnormalizeStep.get_config)
and restored on load by PolicyProcessorPipeline.from_pretrained, so the constants are
dead at eval/load time for the released checkpoints (verified: libero_long/robotwin/base
all carry their quantiles on the Hub).

- Remove LIBERO_ACTION_Q01/Q99, ROBOTWIN_ACTION_Q01/Q99 and _default_action_quantiles.
- make_lingbot_va_pre_post_processors now defaults a fresh (unconverted) build to a
  neutral [-1, 1] mapping (identity rescale); real per-benchmark stats come from the
  saved checkpoint (or postprocessor_overrides), analogous to dataset-stats normalization.
- Update the config doc comment to point at the checkpoint as the source of truth.
- Tests: replace the LIBERO-default assertion with a neutral-default check, and add a
  save_pretrained/from_pretrained round-trip guard for the quantile serialization.

* docs(lingbot_va): trim verbose comments

- configuration_lingbot_va.py: condense multi-line field comments to one-liners
  (keep the ── section headers).
- processor_lingbot_va.py: shorten the action-quantile explanation block.
- modeling_lingbot_va.py: drop the bare "# ----" separator rules, keeping the
  one-line section headers.

No code changes.

* docs(lingbot_va): trim provenance comments; default wan path to base repo

- configuration_lingbot_va.py: drop the "──" decorations and the
  "(from transformer/config.json)" note; default wan_pretrained_path to
  robbyant/lingbot-va-base (has the frozen vae/text_encoder/tokenizer subfolders).
- modeling_lingbot_va.py: remove the vendored-code banner and the
  "(upstream wan_va/...)" section-header provenance/dash decorations; condense the
  transformer-dtype comment to one line.

No code changes.

* refactor(lingbot_va): use built-in UnnormalizerProcessorStep for actions

Replace the bespoke LingBotVAActionUnnormalizeStep with the standard
UnnormalizerProcessorStep in QUANTILES mode, which computes the identical
(action + 1) / 2 * (q99 - q01) + q01 mapping. The per-channel q01/q99 are stored
as the step's saved state (a safetensors file) and restored on load; a fresh build
has no action stats so the step is an identity passthrough.

The 3 Hub checkpoints (lerobot/lingbot_va_{libero_long,robotwin,base}) have been
re-uploaded with the new post-processor (policy_postprocessor.json +
*_unnormalizer_processor.safetensors); reloading from the Hub round-trips q01/q99.

- processor_lingbot_va.py: drop the custom step + registry; build the post-processor
  with UnnormalizerProcessorStep (explicit ACTION->QUANTILES norm_map so the
  preprocessor / training path is unchanged).
- tests: assert the built-in step is used, identity-when-no-stats, correct quantile
  unnormalization, and a save_pretrained/from_pretrained stats round-trip.

* docs(lingbot_va): point checkpoint paths at the lerobot org

The LeRobot-format checkpoints moved from pepijn223/* to lerobot/* (libero_long,
robotwin, base). Update the eval/train --policy.path examples accordingly.

* docs(lingbot_va): condense processor normalization comments

* fix(lingbot-va): align RoboTwin evaluation (#3784)

Thank you for the RoboTwin fix, and alignment!

* applying fixes

* updating uv lock and linting

* adjusting test to match expected values

* cleaning up deps

* cleaning up top level imports, styling, and deps guards

* cleanup
* moving wan utils and loading utils to `utils.py`
* removing ftfy by replicating the prompt_clean function without it (we don't expect to have weird chars given in the prompt anyway)

* removing unused function

* guarding for scipy dep, renaming test to avoid collision

* adding back accelerate for peak memory usage optim + justifying robotwin description dep

---------

Signed-off-by: Pepijn <138571049+pkooij@users.noreply.github.com>
Co-authored-by: pepijn223 <pepijn223@hf.co>
Co-authored-by: Gangwei XU <gwxu@hust.edu.cn>
Co-authored-by: Maxime Ellerbach <maxime.ellerbach@huggingface.co>
2026-07-03 13:32:38 +02:00

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# LingBot-VA
LingBot-VA is an **autoregressive video-action world-model policy** built on the **Wan2.2**
video-diffusion stack. It interleaves, in one autoregressive sequence, the prediction of
future **video latents** and **robot actions** ("VA" = Video-Action). The LeRobot
integration wires LingBot-VA into the standard training, evaluation and processor
interfaces.
## Model Overview
LingBot-VA is a **dual-stream "mixture-of-transformers"**: a video/latent stream
(`patch_embedding_mlp → blocks → proj_out`) and an action stream
(`action_embedder → blocks → action_proj_out`) share the same 30 transformer blocks and
text conditioning.
| Component | Class | Role |
| ------------------------ | ----------------------- | ----------------------------------------------------------- |
| DiT backbone (trainable) | `WanTransformer3DModel` | ~5B-param dual-stream transformer. |
| VAE (frozen) | `AutoencoderKLWan` | Wan2.2 VAE, `z_dim=48`. Lazy-pulled from the source repo. |
| Text encoder (frozen) | `UMT5EncoderModel` | UMT5-XXL, `d_model=4096`. Lazy-pulled from the source repo. |
At inference the policy runs an autoregressive loop per chunk: it denoises the video-latent
stream (CFG, ~20 steps) and the action stream (~50 steps) with two independent
flow-matching schedulers, maintaining a KV cache across chunks. Real observed keyframes are
fed back into the KV cache as the chunk is executed (closed-loop world modeling).
### What the LeRobot Integration Covers
- Standard `policy.type=lingbot_va` configuration through LeRobot.
- Ready-to-use LeRobot-format checkpoints on the Hub (converted from the released upstream ones).
- Autoregressive dual-stream inference behind the standard `select_action` interface
(single-environment eval, `--eval.batch_size=1`).
- Opt-in saving of the policy's **predicted (imagined) videos** during eval / training.
- Evaluation with `lerobot-eval` on LIBERO and RoboTwin.
- Training / fine-tuning via the dual-stream flow-matching loss (`policy.forward`), see below.
## Installation
1. Install LeRobot by following the [Installation Guide](./installation).
2. Install the LingBot-VA extra:
```bash
pip install -e ".[lingbot_va]"
```
## Checkpoints
The released upstream checkpoints have been converted to LeRobot format and pushed to the Hub:
| Variant | LeRobot checkpoint |
| ---------------------- | -------------------------------- |
| LIBERO-Long post-train | `lerobot/lingbot_va_libero_long` |
| RoboTwin post-train | `lerobot/lingbot_va_robotwin` |
| Pretrained base | `lerobot/lingbot_va_base` |
Only the trainable ~5B transformer is stored in the LeRobot
`model.safetensors`. The frozen VAE + UMT5 + tokenizer (~20 GB) are pulled from
`config.wan_pretrained_path` at load time (defaults to the source `robbyant/*` repo). The
UMT5-XXL text encoder runs on CPU by default (`config.text_encoder_device`) so the 5B
transformer + VAE fit on a single 2432 GB GPU.
## Evaluation (LIBERO)
```bash
lerobot-eval \
--policy.path=lerobot/lingbot_va_libero_long \
--policy.device=cuda \
--env.type=libero --env.task=libero_10 \
--env.observation_height=128 --env.observation_width=128 \
--eval.n_episodes=50 --eval.batch_size=1 \
--output_dir=outputs/eval/lingbot_va_libero
```
LingBot-VA's streaming inference (KV cache + observed-keyframe feedback) is implemented for
single-environment eval; use `--eval.batch_size=1`.
## Evaluation (RoboTwin)
RoboTwin 2.0 needs the SAPIEN + CuRobo simulator stack. You can use the benchmark Docker image
(`docker/Dockerfile.benchmark.robotwin`, which also needs `warp-lang==1.3.1` and CuRobo built
with the GPU's compute capability in `TORCH_CUDA_ARCH_LIST`). RoboTwin uses **end-effector-pose
control**, so run with `--env.action_mode=ee`: the policy predicts per-arm `xyz+quaternion+gripper`
deltas (`robotwin_tshape` latent layout) that are composed onto the episode's initial eef pose and
executed via CuRobo IK.
```bash
lerobot-eval \
--policy.path=lerobot/lingbot_va_robotwin \
--policy.device=cuda \
--env.type=robotwin --env.task=beat_block_hammer --env.action_mode=ee \
--eval.n_episodes=10 --eval.batch_size=1 \
--output_dir=outputs/eval/lingbot_va_robotwin
```
### Saving predicted (imagined) videos
Set `--policy.save_predicted_video=true` to additionally VAE-decode the predicted video
latents and write `pred_episode_*.mp4` next to the env-rendered `eval_episode_*.mp4` videos.
The same flag works for the periodic eval during `lerobot-train`.
## Training / fine-tuning
`LingBotVAPolicy.forward(batch)` implements the dual-stream **flow-matching** loss
(`latent_loss + action_loss`, timestep-weighted, action-masked) from the paper: it VAE-encodes
the camera clips into video latents, UMT5-encodes the task, noises both streams, runs the
transformer's block-causal training pass and returns `(loss, metrics)`. Optimizer preset is AdamW
with a linear-warmup-then-constant schedule (matching upstream).
Requirements:
- The block-causal masks use PyTorch **flex-attention**, so build the policy with
`--policy.attn_mode=flex` for training (the default `torch` SDPA is inference-only).
- The full 5B DiT does not fit a single 2432 GB GPU under AdamW; fine-tune with **LoRA**
(`--policy.use_peft=true`) and/or optimizer offload. `get_optim_params` returns only the
trainable (e.g. adapter) parameters; the VAE + UMT5 text encoder stay frozen.
```bash
lerobot-train \
--policy.path=lerobot/lingbot_va_libero_long --policy.attn_mode=flex \
--policy.use_peft=true \
--dataset.repo_id=<your LeRobot-format dataset> \
--batch_size=1 --steps=... --output_dir=outputs/train/lingbot_va
```
The dataset must provide camera clips (a temporal window per camera, VAE-encoded to
`frame_chunk_size` latent frames) and `frame_chunk_size * action_per_frame` action steps per item.
## Data format (action channels & camera order)
LingBot-VA is an **end-effector (Cartesian) pose** policy, it predicts EEF poses + gripper, not
joint positions. Actions live in a fixed multi-embodiment **30-dim** layout; map your robot's
action dimensions into these channels and pad the rest with `0` (`used_action_channel_ids` selects
the channels a given checkpoint actually uses):
| channels | meaning |
| -------- | ----------------------------------------------------- |
| 06 | Left-arm end-effector pose |
| 713 | Right-arm end-effector pose |
| 1420 | Left-arm joints (unused by the released checkpoints) |
| 2127 | Right-arm joints (unused by the released checkpoints) |
| 28 | Left gripper |
| 29 | Right gripper |
- **LIBERO** uses channels `06`: a 6-DoF EEF delta (xyz + rotation) + gripper (single arm).
- **RoboTwin** uses channels `[06, 28, 713, 29]`: left EEF (xyz + quaternion) + left gripper +
right EEF + right gripper (16 dims). The env converts these poses to joint trajectories via
CuRobo IK — joints are never predicted.
Joint-space datasets (or a different EEF convention) must be remapped into this schema before
fine-tuning these checkpoints.
**Camera order is fixed and order-sensitive**, per-camera latents are concatenated spatially in
`obs_cam_keys` order, so the physical camera→slot mapping must match training:
| benchmark | `obs_cam_keys` (in order) | `camera_layout` |
| --------- | ----------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------- |
| LIBERO | `observation.images.image` (agentview / 3rd-person), `observation.images.image2` (eye-in-hand wrist) | `width_concat` (latents concatenated on width) |
| RoboTwin | `observation.images.head_camera`, `observation.images.left_camera`, `observation.images.right_camera` | `robotwin_tshape` (full-res head below, two half-res wrists on top) |
The first camera is the exterior/head view and the rest are wrist views.
## Inference Hyperparameters (LIBERO)
| Key | Value |
| -------------------------------------- | --------------------------------------------------------------------------------- |
| height × width | 128 × 128 |
| cameras | `observation.images.image` (agentview), `observation.images.image2` (eye-in-hand) |
| action channels used | 06 (7-DoF arm + gripper) |
| action_per_frame / frame_chunk_size | 4 / 4 |
| attn_window | 30 |
| video / action denoising steps | 20 / 50 |
| guidance_scale / action_guidance_scale | 5 / 1 |
| snr_shift / action_snr_shift | 5.0 / 0.05 |
These are the defaults of `LingBotVAConfig`; override any of them via `--policy.<name>=...`.
## Notes
- **Attention backend:** inference uses the `torch` SDPA backend (always available). The
`flashattn` and `flex` backends are optional; `flex` is only needed for training.
- **Model size:** the DiT is ~5B params and the frozen VAE+UMT5 add ~20 GB; inference needs
roughly 1824 GB of VRAM.
## License
LingBot-VA is released under Apache-2.0. See the
[upstream repository](https://github.com/Robbyant/lingbot-va).