adding lerobot-train requirement inside PR checklist

* Add FastWAM policy

* Add FastWAM policy review updates

* big refactor to use models from diffusers and transformers

* changing reproducable results

* preparing for training adding some temporary debug code aswell to visualize model output

* re-parenting of some layers to enable proper zero-3 FSDP

* linting

* small fix for the preprocessor and padded images

* removing some preprocessors

* removing temporary debug code

* cleaning up

* updating uv lock after rebasing

* adding lazy imports

* linting

* fixing stale assertion

* make tokenizer/text-encoder model ids configurable + some nits

* moving and renaming files to have a cleaner file tree

* removed asserts from the model, added guard instead and completely removed useless asserts

* cleaning up imports

* removing is_main_process and custom logging logic

* removing unused / stale attention path, removing some of the stale forwards within wan/models

---------

Co-authored-by: ZibinDong <zibindong@outlook.com>
Co-authored-by: Steven Palma <imstevenpmwork@ieee.org>

.github/workflows/benchmark_tests.yml

@@ -167,9 +167,9 @@ jobs:
 
       # ── LIBERO TRAIN+EVAL SMOKE ──────────────────────────────────────────────
       # Train SmolVLA for 1 step (batch_size=1, dataset episode 0 only) then
-      # immediately runs eval inside the training loop (eval_freq=1, 1 episode).
+      # immediately runs eval inside the training loop (env_eval_freq=1, 1 episode).
       # Tests the full train→eval-within-training pipeline end-to-end.
-      - name: Run Libero train+eval smoke (1 step, eval_freq=1)
+      - name: Run Libero train+eval smoke (1 step, env_eval_freq=1)
         if: env.HF_USER_TOKEN != ''
         run: |
           docker run --name libero-train-smoke --gpus all \
@@ -196,7 +196,7 @@ jobs:
                 --output_dir=/tmp/train-smoke \
                 --steps=1 \
                 --batch_size=1 \
-                --eval_freq=1 \
+                --env_eval_freq=1 \
                 --eval.n_episodes=1 \
                 --eval.batch_size=1 \
                 --eval.use_async_envs=false \

AGENTS.md

@@ -51,6 +51,7 @@ pre-commit run --all-files                           # Lint + format (ruff, typo
 ## Notes
 
 - **Mypy is gradual**: strict only for `lerobot.envs`, `lerobot.configs`, `lerobot.optim`, `lerobot.model`, `lerobot.cameras`, `lerobot.motors`, `lerobot.transport`. Add type annotations when modifying these modules.
-- **Optional dependencies**: many policies, envs, and robots are behind extras (e.g., `lerobot[aloha]`). New imports for optional packages must be guarded or lazy. See `pyproject.toml [project.optional-dependencies]`.
+- **Imports**: prefer top-level imports; relative (`from .sibling import X`) across sibling files within a module, absolute (`from lerobot.module import X`) across modules.
+- **Optional dependencies**: many policies, envs, and robots are behind extras (e.g., `lerobot[aloha]`, see `pyproject.toml`). Guard optional imports with `TYPE_CHECKING or _foo_available` at module top + a `require_package(...)` check at use time. Reuse the `_foo_available` flags in `utils/import_utils.py`; don't call `is_package_available`.
 - **Video decoding**: datasets can store observations as video files. `LeRobotDataset` handles frame extraction, but tests need ffmpeg installed.
 - **Prioritize use of `uv run`** to execute Python commands (not raw `python` or `pip`).

AGENT_GUIDE.md

@@ -138,7 +138,7 @@ lerobot-replay --robot.type=so101_follower --robot.port=<FOLLOWER_PORT> --robot.
   --dataset.repo_id=${HF_USER}/my_task --dataset.episode=0
 ```
 
-**4.9 Train** (default: ACT — fastest, lowest memory). Apple silicon: `--policy.device=mps`. See §6/§7 for policy and duration.
+**4.9 Train** (default: ACT — fastest, lowest memory). Apple silicon: `--policy.device=mps`. No local GPU? Add `--job.target=<flavor>` (e.g. `a10g-small`, list them with `hf jobs hardware`) to run on Hugging Face Jobs instead. See §6/§7 for policy and duration.
 
 ```bash
 lerobot-train \

Makefile

@@ -58,7 +58,7 @@ test-act-ete-train:
 		--dataset.episodes="[0]" \
 		--batch_size=2 \
 		--steps=4 \
-		--eval_freq=2 \
+		--env_eval_freq=2 \
 		--eval.n_episodes=1 \
 		--eval.batch_size=1 \
 		--save_freq=2 \
@@ -96,7 +96,7 @@ test-diffusion-ete-train:
 		--dataset.episodes="[0]" \
 		--batch_size=2 \
 		--steps=2 \
-		--eval_freq=2 \
+		--env_eval_freq=2 \
 		--eval.n_episodes=1 \
 		--eval.batch_size=1 \
 		--save_checkpoint=true \
@@ -126,7 +126,7 @@ test-tdmpc-ete-train:
 		--dataset.episodes="[0]" \
 		--batch_size=2 \
 		--steps=2 \
-		--eval_freq=2 \
+		--env_eval_freq=2 \
 		--eval.n_episodes=1 \
 		--eval.batch_size=1 \
 		--save_checkpoint=true \
@@ -161,7 +161,7 @@ test-smolvla-ete-train:
 		--dataset.episodes="[0]" \
 		--batch_size=2 \
 		--steps=4 \
-		--eval_freq=2 \
+		--env_eval_freq=2 \
 		--eval.n_episodes=1 \
 		--eval.batch_size=1 \
 		--save_freq=2 \

README.md

@@ -97,7 +97,7 @@ Training a policy is as simple as running a script configuration:
 
 ```bash
 lerobot-train \
-  --policy=act \
+  --policy.type=act \
   --dataset.repo_id=lerobot/aloha_mobile_cabinet
 ```
 

docs/source/_toctree.yml

@@ -69,6 +69,8 @@
     title: VLA-JEPA
   - local: eo1
     title: EO-1
+  - local: fastwam
+    title: FastWAM
   - local: groot
     title: NVIDIA GR00T N1.5
   - local: xvla

docs/source/bring_your_own_policies.mdx

@@ -165,6 +165,8 @@ Batches are flat dictionaries keyed by the constants in [`lerobot.utils.constant
 
 LeRobot uses `PolicyProcessorPipeline`s to normalize inputs and de-normalize outputs around your policy. For a concrete reference, see [`processor_act.py`](https://github.com/huggingface/lerobot/blob/main/src/lerobot/policies/act/processor_act.py) or [`processor_diffusion.py`](https://github.com/huggingface/lerobot/blob/main/src/lerobot/policies/diffusion/processor_diffusion.py).
 
+Pay close attention here: processors are the most common reproducibility pain point. A mismatch in normalization mode (`IDENTITY` vs `MEAN_STD` vs `MIN_MAX` vs `QUANTILES`/`QUANTILE10`) or in which features get normalized will train and eval without erroring, yet silently wreck results. Make sure the modes match how the checkpoint was trained, that the required stats exist (e.g. `QUANTILES` needs `q01`/`q99`), and that the pre- and post-processors stay consistent.
+
 ```python
 # processor_my_policy.py
 from typing import Any
@@ -371,6 +373,7 @@ The general expectations are in [`CONTRIBUTING.md`](https://github.com/huggingfa
 - [ ] Optional deps live behind a `[project.optional-dependencies]` extra and the `TYPE_CHECKING + require_package` guard.
 - [ ] `tests/policies/` updated; backward-compat artifact committed & policy-specific tests.
 - [ ] `src/lerobot/policies/<name>/README.md` symlinked into `docs/source/policy_<name>_README.md`; user-facing `docs/source/<name>.mdx` written and added to `_toctree.yml`.
+- [ ] `lerobot-train --policy.type my_policy ...` runs end-to-end for at least a few steps + save a checkpoint that can be loaded and run by `lerobot-eval` or `lerobot-rollout`.
 - [ ] At least one reproducible benchmark eval in the policy MDX with a published checkpoint (sim benchmark, or real-robot dataset + checkpoint).
 
 The fastest way to get a clean PR is to copy the directory of the existing policy closest to yours, rename, and replace contents method by method. Don't wait until everything is polished — open a draft PR early and iterate with us; reviewers would much rather give feedback on a half-finished branch than a fully-merged one.

docs/source/cameras.mdx

@@ -157,6 +157,14 @@ finally:
 </hfoption>
 </hfoptions>
 
+### Working with depth
+
+The Intel RealSense and Reachy 2 cameras can capture both color and depth in lockstep. Calling `read()` returns the **color** frame as `(H, W, 3)` `uint8`. Calling `read_depth()` returns the **depth map** as `(H, W, 1)` `uint16`, where each pixel value is the distance from the sensor expressed in **millimetres**. A pixel value of `0` typically means "no measurement available" (out-of-range, occluded, or low-confidence).
+
+During recording, the control loop peeks the freshest buffered frames non-blockingly via `read_latest()` (color) and `read_latest_depth()` (depth), adding the depth map as a sibling feature (e.g. `front_depth` next to `front`).
+
+For how depth streams are stored and encoded when recording a dataset, see the [Depth streams](./video_encoding_parameters#depth-streams) section of the video encoding guide.
+
 ## Use your phone's camera
 
 <hfoptions id="use phone">

docs/source/cheat-sheet.mdx

@@ -89,6 +89,36 @@ Control the data recording flow using keyboard shortcuts:
 - Press **Left Arrow (`←`)**: Delete current episode and retry.
 - Press **Escape (`ESC`)**: Stop, encode videos, and upload.
 
+### Recording depth
+
+Intel RealSense cameras (`type: intelrealsense`) record a depth stream when you set `use_depth: true`. Depth is quantized to 12-bit codes and stored as its own video.
+
+```bash
+lerobot-record \
+    ... \
+    --robot.cameras="{ head: {type: intelrealsense, serial_number_or_name: \"0123456789\", width: 640, height: 480, fps: 30, use_depth: true} }" \
+    --dataset.repo_id=${HF_USER}/so101_depth_test \
+    --dataset.single_task="put the red brick in a bowl" \
+    --dataset.depth_encoder.depth_min=0.01 \
+    --dataset.depth_encoder.depth_max=10.0 \
+    --dataset.depth_encoder.shift=0.0 \
+    --dataset.depth_encoder.use_log=true
+```
+
+### Video encoding parameters
+
+RGB and depth streams are encoded independently via the `--dataset.rgb_encoder.*` and `--dataset.depth_encoder.*` keys.
+
+```bash
+lerobot-record \
+    ... \
+    --dataset.rgb_encoder.vcodec=h264 \
+    --dataset.rgb_encoder.pix_fmt=yuv420p \
+    --dataset.rgb_encoder.crf=23 \
+    --dataset.depth_encoder.vcodec=hevc \
+    --dataset.depth_encoder.extra_options='{"x265-params": "lossless=1"}'
+```
+
 ### Training
 
 Depending on your hardware training the policy might take a few hours. That's how you train simple `ACT` policy:
@@ -120,6 +150,14 @@ lerobot-train \
     --steps=20000
 ```
 
+No local GPU? Add `--job.target=<flavor>` (e.g. `a10g-small`) to either command and `lerobot-train` runs it on [Hugging Face Jobs](https://huggingface.co/docs/hub/jobs) instead — it uploads a local-only dataset for you and pushes the trained model. List flavors with `hf jobs hardware`.
+
+To resume, point `--config_path` at a checkpoint and add `--resume=true`. It accepts a local path or a Hub repo id (the latest checkpoint is fetched), and works locally or on a job by adding `--job.target=<flavor>`:
+
+```bash
+lerobot-train --config_path=${HF_USER}/policy_test --resume=true --job.target=a10g-small
+```
+
 ### Inference
 
 Inference means running the trained policy/model on a robot. For that we use `lerobot-rollout`. You will need to provide a path to your policy. It can be a local path or a path to Hugging Face for example "lerobot/folding_latest". Your cameras configuration needs to match what was used when collecting the dataset. Duration is in seconds if unspecified, it will run forever.

docs/source/earthrover_mini_plus.mdx

@@ -194,7 +194,7 @@ lerobot-record \
     --dataset.single_task="Navigate around obstacles" \
     --dataset.streaming_encoding=true \
     --dataset.encoder_threads=2 \
-    # --dataset.camera_encoder.vcodec=auto \
+    # --dataset.rgb_encoder.vcodec=auto \
     --display_data=true
 ```
 

docs/source/fastwam.mdx

@@ -0,0 +1,167 @@
+# FastWAM
+
+FastWAM is a World Action Model policy for robot control. The LeRobot integration exposes FastWAM through the standard policy API so it can be configured with `policy.type=fastwam`, trained with `lerobot-train`, and loaded through the LeRobot pretrained policy interface.
+
+## Model Overview
+
+FastWAM keeps video modeling during training, but uses direct action prediction at inference time instead of iteratively generating future observations. This LeRobot policy wraps the FastWAM action model, adapts LeRobot batches to FastWAM training samples, and provides the standard processor pipeline for normalization and action postprocessing.
+
+The implementation initializes the visual world-model components from `Wan-AI/Wan2.2-TI2V-5B` by default and predicts action chunks with shape `[batch, action_horizon, action_dim]`.
+
+### What the LeRobot Integration Covers
+
+- Standard `policy.type=fastwam` configuration through LeRobot
+- Image, state, action, and language-task batch adaptation
+- Action chunk inference through `select_action` and `predict_action_chunk`
+- Checkpoint save/load through the LeRobot policy APIs
+- Configurable LIBERO gripper action postprocessing
+
+## Installation Requirements
+
+Install LeRobot from source, then install FastWAM dependencies:
+
+```bash
+pip install -e ".[fastwam]"
+```
+
+This installs the FastWAM policy extra from `pyproject.toml`: `transformers`,
+`diffusers`, `ftfy`, and `regex`, plus LeRobot's base dependencies.
+
+For LIBERO evaluation, install the benchmark dependencies too:
+
+```bash
+pip install -e ".[fastwam,libero]"
+```
+
+This installs both extras. In addition to the FastWAM dependencies above, the
+`libero` extra installs LeRobot dataset dependencies, `hf-libero` on Linux, and
+`scipy`.
+
+FastWAM uses the Wan2.2 TI2V backbone. The default model id is:
+
+```python
+policy.model_id=Wan-AI/Wan2.2-TI2V-5B
+```
+
+## Data Requirements
+
+FastWAM expects a LeRobot dataset with:
+
+- one or more visual observations whose widths concatenate to `policy.image_size[1]`
+- `observation.state` when `policy.proprio_dim` is not `None`
+- `action`
+- a language task instruction through the dataset task field, or precomputed `context` and `context_mask` tensors
+
+The default visual setup is one image feature named `observation.images.image` with shape `(3, 224, 448)`. If the dataset uses two cameras, configure `policy.input_features` so their heights match `224` and their widths sum to `448`.
+
+## Usage
+
+Create a new FastWAM policy with:
+
+```bash
+lerobot-train \
+  --dataset.repo_id=your-org/your-dataset \
+  --policy.type=fastwam \
+  --policy.action_dim=7 \
+  --policy.proprio_dim=8 \
+  --policy.action_horizon=32 \
+  --policy.n_action_steps=10 \
+  --policy.image_size='[224,448]' \
+  --output_dir=./outputs/fastwam_training \
+  --job_name=fastwam_training \
+  --steps=300000 \
+  --batch_size=8 \
+  --policy.device=cuda
+```
+
+Evaluate an existing LeRobot-format checkpoint on LIBERO-10 with:
+
+```bash
+lerobot-eval \
+  --policy.path=ZibinDong/fastwam_libero_uncond_2cam224 \
+  --policy.device=cuda \
+  --policy.torch_dtype=float32 \
+  --policy.n_action_steps=10 \
+  --env.type=libero \
+  --env.task=libero_10 \
+  --env.observation_height=224 \
+  --env.observation_width=224 \
+  --eval.batch_size=1 \
+  --eval.n_episodes=50 \
+  --seed=0 \
+  --env.episode_length=600
+```
+
+For `libero_goal`, `libero_spatial`, and `libero_object`, use
+`--env.episode_length=300`.
+
+For real-robot rollout, use the same checkpoint path:
+
+```bash
+lerobot-rollout \
+  --robot.type=so101_follower \
+  --robot.port=/dev/ttyACM0 \
+  --policy.path=your-org/fastwam-real-robot
+```
+
+## Configuration Notes
+
+### Image Features
+
+`policy.image_size` is the size of the concatenated FastWAM image tensor as `(height, width)`. Each configured image feature must have shape `(3, height, camera_width)`, and all camera widths must sum to the configured width.
+
+### Action Chunking
+
+`policy.action_horizon` controls the number of future actions supervised during training and predicted during inference. `policy.n_action_steps` controls how many actions are consumed before the policy predicts a fresh chunk. `policy.n_action_steps` must be less than or equal to `policy.action_horizon`.
+
+### Wan Components
+
+FastWAM loads the Wan VAE, video DiT, text encoder, and tokenizer from the configured Wan model directory or Hugging Face Hub model id. LeRobot-format FastWAM checkpoints saved by `save_pretrained` also copy the local Wan component files needed by `from_pretrained`.
+
+### Attention Backend
+
+FastWAM's DiT uses PyTorch's `scaled_dot_product_attention` (SDPA) for all attention. It does **not** use FlashAttention: its Mixture-of-Transformers (MoT) routing needs arbitrary boolean `[query, key]` attention masks, which the FlashAttention varlen API cannot express. Installing the `flash-attn` package therefore has no effect on the FastWAM path. (Note that SDPA itself may still select PyTorch's own flash / memory-efficient / math kernel internally — this is unrelated to the `flash-attn` package.)
+
+### LIBERO Action Toggle
+
+FastWAM LIBERO checkpoints use `policy.toggle_action_dimensions=[-1]` by
+default to match the gripper action convention used by the original FastWAM
+evaluation pipeline:
+
+```bash
+--policy.toggle_action_dimensions='[-1]'
+```
+
+## Results
+
+Evaluated on LIBERO with [`ZibinDong/fastwam_libero_uncond_2cam224`](https://huggingface.co/ZibinDong/fastwam_libero_uncond_2cam224):
+
+| Suite          | Success rate | n_episodes |
+| -------------- | -----------: | ---------: |
+| libero_spatial |        97.6% |        500 |
+| libero_object  |        99.0% |        500 |
+| libero_goal    |        95.0% |        500 |
+| libero_10      |        94.0% |        500 |
+| **average**    |    **96.4%** |       2000 |
+
+Reproduce: `lerobot-eval --policy.path=ZibinDong/fastwam_libero_uncond_2cam224 --policy.device=cuda --policy.torch_dtype=float32 --policy.n_action_steps=10 --env.type=libero --env.task=libero_spatial --env.observation_height=256 --env.observation_width=256 --eval.batch_size=1 --eval.n_episodes=50 --seed=0 --env.episode_length=300` (1x H20 140 GB).
+
+## References
+
+- [Fast-WAM paper](https://arxiv.org/abs/2603.16666)
+- [Fast-WAM project page](https://yuantianyuan01.github.io/FastWAM/)
+- [Fast-WAM code](https://github.com/yuantianyuan01/FastWAM)
+- [Released upstream checkpoints](https://huggingface.co/yuanty/fastwam)
+- [Wan2.2 TI2V 5B](https://huggingface.co/Wan-AI/Wan2.2-TI2V-5B)
+
+## Citation
+
+```bibtex
+@article{yuan2026fastwam,
+  title = {Fast-WAM: Do World Action Models Need Test-time Future Imagination?},
+  author = {Tianyuan Yuan and Zibin Dong and Yicheng Liu and Hang Zhao},
+  journal = {arXiv preprint arXiv:2603.16666},
+  year = {2026},
+  url = {https://arxiv.org/abs/2603.16666}
+}
+```

docs/source/groot.mdx

@@ -124,7 +124,7 @@ lerobot-rollout\
   --dataset.single_task="Grab and handover the red cube to the other arm" \
   --dataset.streaming_encoding=true \
   --dataset.encoder_threads=2 \
-  # --dataset.camera_encoder.vcodec=auto \
+  # --dataset.rgb_encoder.vcodec=auto \
   --policy.path=<user>/groot-bimanual \ # your trained model
   --duration=600
 ```

docs/source/hardware_guide.mdx

@@ -96,3 +96,4 @@ Notes:
 - The leading `nvidia-smi` is a quick sanity check that CUDA is visible inside the container — useful to fail fast if the flavor or driver mismatched.
 - The default Job timeout is 30 minutes; pass `--timeout 4h` (or longer) for real training.
 - `--flavor` maps onto the table above: `t4-small`/`t4-medium` (T4, ACT only), `l4x1`/`l4x4` (L4 24 GB), `a10g-small/large/largex2/largex4` (A10G 24 GB scaled out), `a100-large` (A100). For the current full catalogue + pricing see [https://huggingface.co/docs/hub/jobs](https://huggingface.co/docs/hub/jobs).
+- Prefer not to write the `hf jobs run` wrapper yourself? `lerobot-train` can submit the job for you: just add `--job.target=<flavor>` to a normal training command and it handles dataset upload, log streaming, and the final model push. See the [imitation-learning training guide](./il_robots).

docs/source/hilserl.mdx

@@ -719,7 +719,7 @@ Example configuration for training the [reward classifier](https://huggingface.c
   "num_workers": 4,
   "steps": 5000,
   "log_freq": 10,
-  "eval_freq": 1000,
+  "env_eval_freq": 1000,
   "save_freq": 1000,
   "save_checkpoint": true,
   "seed": 2,

docs/source/hope_jr.mdx

@@ -232,7 +232,7 @@ lerobot-record \
     --dataset.private=true \
     --dataset.streaming_encoding=true \
     --dataset.encoder_threads=2 \
-    # --dataset.camera_encoder.vcodec=auto \
+    # --dataset.rgb_encoder.vcodec=auto \
     --display_data=true
 ```
 
@@ -278,6 +278,6 @@ lerobot-record \
   --dataset.num_episodes=10 \
   --dataset.streaming_encoding=true \
   --dataset.encoder_threads=2 \
-  # --dataset.camera_encoder.vcodec=auto \
+  # --dataset.rgb_encoder.vcodec=auto \
   --policy.path=outputs/train/hopejr_hand/checkpoints/last/pretrained_model
 ```

docs/source/il_robots.mdx

@@ -207,7 +207,7 @@ lerobot-record \
     --dataset.num_episodes=5 \
     --dataset.single_task="Grab the black cube" \
     --dataset.streaming_encoding=true \
-    # --dataset.camera_encoder.vcodec=auto \
+    # --dataset.rgb_encoder.vcodec=auto \
     --dataset.encoder_threads=2
 ```
 </hfoption>
@@ -390,9 +390,17 @@ Set the flow of data recording using command-line arguments:
 
 Control the data recording flow using keyboard shortcuts:
 
-- Press **Right Arrow (`→`)**: Early stop the current episode or reset time and move to the next.
-- Press **Left Arrow (`←`)**: Cancel the current episode and re-record it.
-- Press **Escape (`ESC`)**: Immediately stop the session, encode videos, and upload the dataset.
+- Press **Right Arrow (`→`)** or **`n`**: Early stop the current episode or reset time and move to the next.
+- Press **Left Arrow (`←`)** or **`r`**: Cancel the current episode and re-record it.
+- Press **Escape (`ESC`)** or **`q`**: Immediately stop the session, encode videos, and upload the dataset.
+
+<Tip>
+
+These control-flow shortcuts work on **X11, Wayland, and headless/SSH** sessions. When a global keyboard backend isn't available (Wayland, a headless machine, or macOS without Accessibility permission), `lerobot-record` automatically reads the same keys from the terminal — launch it from an interactive terminal and keep it focused. You can also use the letter equivalents **`n`** (next, same as `→`), **`r`** (re-record, same as `←`) and **`q`** (quit, same as `ESC`). No `$DISPLAY` setup is required.
+
+This applies to the recording control flow only. Keyboard **teleoperation** (driving the robot with the keyboard) still needs a global key backend, so it works only on an X11 session, a Windows desktop, or macOS with Accessibility/Input Monitoring granted — not on Wayland or headless sessions.
+
+</Tip>
 
 #### Tips for gathering data
 
@@ -406,7 +414,7 @@ If you want to dive deeper into this important topic, you can check out the [blo
 
 #### Troubleshooting:
 
-- On Linux, if the left and right arrow keys and escape key don't have any effect during data recording, make sure you've set the `$DISPLAY` environment variable. See [pynput limitations](https://pynput.readthedocs.io/en/latest/limitations.html#linux).
+- On Linux, the recording control-flow keys (arrow keys, Escape) work on X11, Wayland, and headless/SSH sessions as long as `lerobot-record` runs in an interactive terminal — no `$DISPLAY` setup is needed. If the keys have no effect, make sure you are in an interactive (TTY) terminal, not a piped/non-TTY session, and that it is focused; the letter equivalents `n` / `r` / `q` also work. Keyboard _teleoperation_ (as opposed to the recording control flow) still requires a global key backend — an X11 session, a Windows desktop, or macOS with Accessibility/Input Monitoring granted — and is unavailable on Wayland or headless machines. See [pynput limitations](https://pynput.readthedocs.io/en/latest/limitations.html#linux).
 
 ## Visualize a dataset
 
@@ -506,6 +514,12 @@ lerobot-train \
   --resume=true
 ```
 
+`--config_path` also accepts a **Hub repo id**: if a run pushed its checkpoints to the Hub (with `--save_checkpoint_to_hub=true`), you can resume straight from the repo — its latest checkpoint is downloaded and training continues, restoring the optimizer, scheduler, step counter and data order:
+
+```bash
+lerobot-train --config_path=${HF_USER}/my_policy --resume=true
+```
+
 If you do not want to push your model to the hub after training use `--policy.push_to_hub=false`.
 
 Additionally you can provide extra `tags` or specify a `license` for your model or make the model repo `private` by adding this: `--policy.private=true --policy.tags=\[ppo,rl\] --policy.license=mit`
@@ -518,7 +532,9 @@ If your local computer doesn't have a powerful GPU you could utilize Google Cola
 
 Hugging Face jobs let's you easily select hardware and run the training in the cloud. So if you don't have a powerful GPU or you need more VRAM or just want to train a model much faster use HF Jobs! It's pay as you go and you simply pay for each second of use, you can see the pricing and additional information [here](https://huggingface.co/docs/hub/jobs).
 
-To run the training use this command:
+> **Tip:** if you just want to launch a standard training run, you can skip building the command below and use the integrated **Train on HF Jobs via `--job.target`** flow described further down — `lerobot-train` then submits the job, uploads a local-only dataset for you, and streams the logs.
+
+To run the training manually use this command:
 
 <hfoptions id="train_with_hf_jobs">
 <hfoption id="Command">
@@ -591,6 +607,51 @@ Once the training is started you can go to [Jobs](https://huggingface.co/setting
 
 After training the model will be pushed to hub and you can use it as any other model with LeRobot.
 
+#### Train on HF Jobs via `--job.target` (integrated CLI)
+
+`lerobot-train` runs locally by default. To run on a HuggingFace GPU without constructing the Docker command yourself, pass `--job.target` with a hardware flavor name:
+
+```bash
+lerobot-train \
+  --dataset.repo_id=${HF_USER}/so101_test \
+  --policy.type=act \
+  --policy.repo_id=${HF_USER}/my_policy \
+  --job.target=a10g-small
+```
+
+List available flavors and pricing with `hf jobs hardware`. The run streams its logs to your terminal; press Ctrl-C to detach (the job keeps running in the cloud). Re-attach or cancel with:
+
+```bash
+hf jobs logs <job-id>
+hf jobs cancel <job-id>
+```
+
+If your dataset exists only locally (not yet on the Hub), it is automatically pushed to a **private** Hub repo so the job can download it by `repo_id` (nothing is made public). The trained model is pushed to the model repo at the end of the run. To also push every intermediate checkpoint to the Hub as it is saved (so you can monitor progress mid-run), add `--save_checkpoint_to_hub=true` — this requires a runtime image that includes this feature.
+
+Every job (and any dataset pushed by the run) is tagged `lerobot` so it's easy to find on the Hub. Add your own with `--job.tags '["my-tag"]'`.
+
+By default the job is capped at `2d` (48h) of wall-clock. Override it with an HF Jobs duration string, e.g. `--job.timeout=4h` to fail faster or `--job.timeout=7d` for a longer run.
+
+> **Note:** the model repo is created up front (it holds the staged training config the job runs from). If a run fails before the model is pushed, that repo is left on the Hub so you can inspect it — it is not deleted automatically, so repeated failures can leave empty repos behind. Remove one with `hf repo delete <repo-id>`.
+
+**Prerequisites:** run `hf auth login` before submitting. For Weights & Biases integration, run `wandb login` or set `WANDB_API_KEY` on your machine — the key is forwarded to the job automatically.
+
+**Resuming on a job.** Adding `--job.target` to a resume command runs the resume in the cloud — the same command works locally or remotely. The checkpoint repo is the source of truth, and new checkpoints continue the lineage in the same repo:
+
+```bash
+# resume a Hub run on a job (its checkpoints are already on the Hub)
+lerobot-train --config_path=${HF_USER}/my_policy --resume=true --job.target=a10g-small
+
+# resume a LOCAL run on a job — the checkpoint is uploaded to a private Hub repo first,
+# then the job resumes from it (a local-only dataset is uploaded the same way)
+lerobot-train \
+  --config_path=outputs/train/act_so101_test/checkpoints/last/pretrained_model/train_config.json \
+  --resume=true \
+  --job.target=a10g-small
+```
+
+Job settings come from the current command, so override `--job.target`, `--job.timeout`, etc. as needed; for the resumed run to itself be resumable later, keep `--save_checkpoint_to_hub=true`.
+
 #### Upload policy checkpoints
 
 Once training is done, upload the latest checkpoint with:
@@ -612,6 +673,8 @@ hf upload ${HF_USER}/act_so101_test${CKPT} \
 
 Use `lerobot-rollout` to deploy a trained policy on your robot. You can choose different strategies depending on your needs:
 
+The examples below load the model from `--policy.path`. To pin a specific pushed version — useful once `--save_checkpoint_to_hub=true` has committed several checkpoints — add `--policy.pretrained_revision` with a commit hash, branch, or tag. Each pushed checkpoint is tagged with its step (e.g. `--policy.pretrained_revision=010000`), so you can recover a checkpoint by step without looking up its commit sha.
+
 <hfoptions id="eval">
 <hfoption id="Base mode (no recording)">
 ```bash

docs/source/lekiwi.mdx

@@ -319,7 +319,7 @@ If you want to dive deeper into this important topic, you can check out the [blo
 
 #### Troubleshooting:
 
-- On Linux, if the left and right arrow keys and escape key don't have any effect during data recording, make sure you've set the `$DISPLAY` environment variable. See [pynput limitations](https://pynput.readthedocs.io/en/latest/limitations.html#linux).
+- On Linux, the recording control-flow keys (arrow keys, Escape) work on X11, Wayland, and headless/SSH sessions as long as you run the recording from an interactive terminal (keep it focused) — no `$DISPLAY` setup is needed; the letter equivalents `n` / `r` / `q` also work. Note that **keyboard teleoperation of the LeKiwi base** is different: it relies on a global key backend and therefore works only on an X11 session, a Windows desktop, or macOS with Accessibility/Input Monitoring granted — not on Wayland or headless machines. See [pynput limitations](https://pynput.readthedocs.io/en/latest/limitations.html#linux).
 
 ## Replay an episode
 

docs/source/lerobot-dataset-v3.mdx

@@ -44,7 +44,7 @@ lerobot-record \
   --dataset.num_episodes=5 \
   --dataset.single_task="Grab the black cube" \
   --dataset.streaming_encoding=true \
-  # --dataset.camera_encoder.vcodec=auto \
+  # --dataset.rgb_encoder.vcodec=auto \
   --dataset.encoder_threads=2
 ```
 

docs/source/libero.mdx

@@ -143,7 +143,7 @@ lerobot-train \
   --batch_size=4 \
   --eval.batch_size=1 \
   --eval.n_episodes=1 \
-  --eval_freq=1000
+  --env_eval_freq=1000
 ```
 
 ## Reproducing published results

docs/source/libero_plus.mdx

@@ -173,7 +173,7 @@ lerobot-train \
     --batch_size=4 \
     --eval.batch_size=1 \
     --eval.n_episodes=1 \
-    --eval_freq=1000
+    --env_eval_freq=1000
 ```
 
 ## Relationship to LIBERO

docs/source/metaworld.mdx

@@ -120,11 +120,11 @@ lerobot-train \
   --batch_size=4 \
   --eval.batch_size=1 \
   --eval.n_episodes=1 \
-  --eval_freq=1000
+  --env_eval_freq=1000
 ```
 
 ## Practical tips
 
 - Use the one-hot task conditioning for multi-task training (MT10/MT50 conventions) so policies have explicit task context.
 - Inspect the dataset task descriptions and the `info["is_success"]` keys when writing post-processing or logging so your success metrics line up with the benchmark.
-- Adjust `batch_size`, `steps`, and `eval_freq` to match your compute budget.
+- Adjust `batch_size`, `steps`, and `env_eval_freq` to match your compute budget.

docs/source/molmoact2.mdx

@@ -17,7 +17,7 @@ the paper, see [allenai/molmoact2](https://github.com/allenai/molmoact2).
 Install LeRobot with the MolmoAct2 optional dependencies:
 
 ```bash
-pip install -e ".[molmoact2]"
+uv sync --locked --extra molmoact2
 ```
 
 To run the models in this repository, you need an NVIDIA GPU. The measurements
@@ -46,8 +46,8 @@ The repo has been tested with Ubuntu 22.04.
 
 To use MolmoAct2 in a LeRobot training config, set:
 
-```python
-policy.type=molmoact2
+```bash
+--policy.type=molmoact2
 ```
 
 ## Training
@@ -103,7 +103,7 @@ accelerate launch \
   --batch_size=32 \
   --num_workers=4 \
   --log_freq=20 \
-  --eval_freq=-1 \
+  --env_eval_freq=-1 \
   --save_checkpoint=true \
   --save_freq=2000
 ```
@@ -142,7 +142,7 @@ accelerate launch \
   --batch_size=32 \
   --num_workers=4 \
   --log_freq=20 \
-  --eval_freq=-1 \
+  --env_eval_freq=-1 \
   --save_checkpoint=true \
   --save_freq=2000
 ```
@@ -386,6 +386,68 @@ These results demonstrate MolmoAct2's strong performance across diverse robotic
 manipulation tasks. To reproduce them, follow the instructions in the LIBERO
 evaluation section.
 
+## Hardware Deployment (lerobot-rollout)
+
+LeRobot-format checkpoints are available on the Hub for direct use with
+`lerobot-rollout`. Each checkpoint uses specific camera names that must
+match your robot's camera configuration.
+
+### Camera naming convention
+
+Each checkpoint expects specific `observation.images.*` keys.
+If your robot cameras have different names, use `--rename_map` to map them:
+
+| Checkpoint                    | Camera keys            | Description              |
+| ----------------------------- | ---------------------- | ------------------------ |
+| MolmoAct2-LIBERO-LeRobot      | `image`, `wrist_image` | LIBERO sim cameras       |
+| MolmoAct2-BimanualYAM-LeRobot | `top`, `left`, `right` | YAM 3-camera setup       |
+| MolmoAct2-DROID-LeRobot       | `cam0`, `cam1`         | External + wrist         |
+| MolmoAct2-SO100_101-LeRobot   | `cam0`, `cam1`         | Primary + secondary view |
+
+Example with an SO-100 robot using top and side cameras:
+
+```bash
+lerobot-rollout \
+  --policy.path=lerobot/MolmoAct2-SO100_101-LeRobot \
+  --rename_map='{"observation.images.top": "observation.images.cam0", "observation.images.side": "observation.images.cam1"}' \
+  --robot.type=so100_follower \
+  --robot.port=/dev/ttyACM0 \
+  --robot.cameras='{
+      top: {type: opencv, index_or_path: 0, width: 640, height: 480, fps: 30},
+      side: {type: opencv, index_or_path: 2, width: 640, height: 480, fps: 30}
+  }' \
+  --task="pick up the red cube" --duration=30
+```
+
+To use a wrist camera instead, just change the rename mapping:
+
+```bash
+--rename_map='{"observation.images.top": "observation.images.cam0", "observation.images.wrist": "observation.images.cam1"}'
+```
+
+### Joint frame transform (SO-100/101 zero-shot)
+
+<Tip warning={true}>
+The MolmoAct2-SO100_101 checkpoint was trained on data that uses a different
+joint calibration convention than LeRobot >= 0.5.0. Without a frame
+correction, the arm may move in the wrong direction.
+
+This affects both **zero-shot deployment** and **fine-tuning** from the
+original checkpoint. The pretrained weights expect the old convention, so
+all joint data (observations and actions) must be transformed to match.
+
+The converted LeRobot checkpoint (`lerobot/MolmoAct2-SO100_101-LeRobot`)
+already includes this correction in its processor pipeline. If you convert
+or fine-tune the checkpoint yourself, set the following in the policy config (`configuration_molmoact2.py`):
+
+- `joint_signs`: `[1, -1, 1, 1, 1, 1]` (flips shoulder_lift direction)
+- `joint_offsets`: `[0, 90, 90, 0, 0, 0]` (shifts shoulder_lift and elbow_flex by 90°)
+
+See the [backward compatibility guide](./backwardcomp) for details on the
+calibration change.
+
+</Tip>
+
 ## Differences From the Original Implementation
 
 This LeRobot port is intended to match MolmoAct2 behavior while using LeRobot's

docs/source/multi_gpu_training.mdx

@@ -95,7 +95,7 @@ If you want to scale your hyperparameters when using multiple GPUs, you should d
 accelerate launch --num_processes=2 $(which lerobot-train) \
   --optimizer.lr=2e-4 \
   --dataset.repo_id=lerobot/pusht \
-  --policy=act
+  --policy.type=act
 ```
 
 **Training Steps Scaling:**
@@ -110,7 +110,7 @@ accelerate launch --num_processes=2 $(which lerobot-train) \
   --batch_size=8 \
   --steps=50000 \
   --dataset.repo_id=lerobot/pusht \
-  --policy=act
+  --policy.type=act
 ```
 
 ## Training Large Models with FSDP

docs/source/multi_task_dit.mdx

@@ -314,7 +314,7 @@ lerobot-train \
   --steps=30000 \
   --save_freq=1000 \
   --log_freq=100 \
-  --eval_freq=1000 \
+  --env_eval_freq=1000 \
   --policy.type=multi_task_dit \
   --policy.device=cuda \
   --policy.horizon=32 \

docs/source/pi0fast.mdx

@@ -96,7 +96,7 @@ lerobot-train \
     --policy.type=pi0_fast \
     --output_dir=./outputs/pi0fast_training \
     --job_name=pi0fast_training \
-    --policy.pretrained_path=lerobot/pi0_fast_base \
+    --policy.pretrained_path=lerobot/pi0fast-base \
     --policy.dtype=bfloat16 \
     --policy.gradient_checkpointing=true \
     --policy.chunk_size=10 \
@@ -187,7 +187,7 @@ lerobot-train \
   --dataset.repo_id=lerobot/libero \
   --output_dir=outputs/libero_pi0fast \
   --job_name=libero_pi0fast \
-  --policy.path=lerobot/pi0fast_base \
+  --policy.path=lerobot/pi0fast-base \
   --policy.dtype=bfloat16 \
   --steps=100000 \
   --save_freq=20000 \

docs/source/policy_fastwam_README.md

@@ -0,0 +1,56 @@
+## Research Paper
+
+Paper: https://arxiv.org/abs/2603.16666
+
+## Repository
+
+Code: https://github.com/yuantianyuan01/FastWAM
+
+Project page: https://yuantianyuan01.github.io/FastWAM/
+
+## Citation
+
+```bibtex
+@article{yuan2026fastwam,
+  title = {Fast-WAM: Do World Action Models Need Test-time Future Imagination?},
+  author = {Tianyuan Yuan and Zibin Dong and Yicheng Liu and Hang Zhao},
+  journal = {arXiv preprint arXiv:2603.16666},
+  year = {2026},
+  url = {https://arxiv.org/abs/2603.16666}
+}
+```
+
+## Additional Resources
+
+Base video model: https://huggingface.co/Wan-AI/Wan2.2-TI2V-5B
+
+Released upstream checkpoints: https://huggingface.co/yuanty/fastwam
+
+## Results
+
+Evaluated on LIBERO with [`ZibinDong/fastwam_libero_uncond_2cam224`](https://huggingface.co/ZibinDong/fastwam_libero_uncond_2cam224):
+
+| Suite          | Success rate | n_episodes |
+| -------------- | -----------: | ---------: |
+| libero_spatial |        97.6% |        500 |
+| libero_object  |        99.0% |        500 |
+| libero_goal    |        95.0% |        500 |
+| libero_10      |        94.0% |        500 |
+| **average**    |    **96.4%** |       2000 |
+
+Reproduce: `lerobot-eval --policy.path=ZibinDong/fastwam_libero_uncond_2cam224 --policy.device=cuda --policy.torch_dtype=float32 --policy.n_action_steps=10 --env.type=libero --env.task=libero_spatial --env.observation_height=256 --env.observation_width=256 --eval.batch_size=1 --eval.n_episodes=50 --seed=0 --env.episode_length=300`.
+
+For LIBERO-10, use `--env.task=libero_10 --env.episode_length=600`:
+
+```bash
+lerobot-eval \
+    --policy.path=ZibinDong/fastwam_libero_uncond_2cam224 \
+    --policy.device=cuda \
+    --policy.torch_dtype=float32 \
+    --policy.n_action_steps=10 \
+    --env.type=libero \
+    --env.task=libero_10 --env.observation_height=256 --env.observation_width=256 \
+    --eval.batch_size=1 \
+    --eval.n_episodes=50 \
+    --seed=0 --env.episode_length=600
+```

docs/source/reachy2.mdx

@@ -161,7 +161,7 @@ lerobot-record \
     --dataset.private=true \
     --dataset.streaming_encoding=true \
     --dataset.encoder_threads=2 \
-    # --dataset.camera_encoder.vcodec=auto \
+    # --dataset.rgb_encoder.vcodec=auto \
     --display_data=true
 ```
 
@@ -203,7 +203,7 @@ lerobot-record \
     --dataset.private=true \
     --dataset.streaming_encoding=true \
     --dataset.encoder_threads=2 \
-    # --dataset.camera_encoder.vcodec=auto \
+    # --dataset.rgb_encoder.vcodec=auto \
     --display_data=true
 ```
 

docs/source/robocasa.mdx

@@ -166,7 +166,7 @@ lerobot-train \
   --output_dir=./outputs/smolvla_robocasa_CloseFridge \
   --steps=100000 \
   --batch_size=4 \
-  --eval_freq=5000 \
+  --env_eval_freq=5000 \
   --eval.batch_size=1 \
   --eval.n_episodes=5 \
   --save_freq=10000

docs/source/so101.mdx

@@ -122,7 +122,7 @@ The video below shows the sequence of steps for setting the motor ids.
 
 #### Follower
 
-Connect the usb cable from your computer and the power supply to the follower arm's controller board. Then, run the following command or run the API example with the port you got from the previous step. You'll also need to give your leader arm a name with the `id` parameter.
+Connect the usb cable from your computer and the power supply to the follower arm's controller board. Then, run the following command or run the API example with the port you got from the previous step. You'll also need to give your follower arm a name with the `id` parameter.
 
 <hfoptions id="setup_motors">
 <hfoption id="Command">

docs/source/streaming_video_encoding.mdx

@@ -17,7 +17,7 @@ This makes `save_episode()` near-instant (the video is already encoded by the ti
 | Parameter               | CLI Flag                          | Type          | Default       | Description                                                       |
 | ----------------------- | --------------------------------- | ------------- | ------------- | ----------------------------------------------------------------- |
 | `streaming_encoding`    | `--dataset.streaming_encoding`    | `bool`        | `True`        | Enable real-time encoding during capture                          |
-| `vcodec`                | `--dataset.camera_encoder.vcodec` | `str`         | `"libsvtav1"` | Video codec. `"auto"` detects best HW encoder                     |
+| `vcodec`                | `--dataset.rgb_encoder.vcodec`    | `str`         | `"libsvtav1"` | Video codec. `"auto"` detects best HW encoder                     |
 | `encoder_threads`       | `--dataset.encoder_threads`       | `int \| None` | `None` (auto) | Threads per encoder instance. `None` will leave the vcoded decide |
 | `encoder_queue_maxsize` | `--dataset.encoder_queue_maxsize` | `int`         | `30`          | Max buffered frames per camera (~1s at 30fps). Consumes RAM       |
 
@@ -82,15 +82,15 @@ Use HW encoding when:
 
 ### Available HW Encoders
 
-| Encoder             | Platform      | Hardware                                                                                         | CLI Value                                           |
-| ------------------- | ------------- | ------------------------------------------------------------------------------------------------ | --------------------------------------------------- |
-| `h264_videotoolbox` | macOS         | Apple Silicon / Intel                                                                            | `--dataset.camera_encoder.vcodec=h264_videotoolbox` |
-| `hevc_videotoolbox` | macOS         | Apple Silicon / Intel                                                                            | `--dataset.camera_encoder.vcodec=hevc_videotoolbox` |
-| `h264_nvenc`        | Linux/Windows | NVIDIA GPU                                                                                       | `--dataset.camera_encoder.vcodec=h264_nvenc`        |
-| `hevc_nvenc`        | Linux/Windows | NVIDIA GPU                                                                                       | `--dataset.camera_encoder.vcodec=hevc_nvenc`        |
-| `h264_vaapi`        | Linux         | Intel/AMD GPU                                                                                    | `--dataset.camera_encoder.vcodec=h264_vaapi`        |
-| `h264_qsv`          | Linux/Windows | Intel Quick Sync                                                                                 | `--dataset.camera_encoder.vcodec=h264_qsv`          |
-| `auto`              | Any           | Probes the system for available HW encoders. Falls back to `libsvtav1` if no HW encoder is found | `--dataset.camera_encoder.vcodec=auto`              |
+| Encoder             | Platform      | Hardware                                                                                         | CLI Value                                        |
+| ------------------- | ------------- | ------------------------------------------------------------------------------------------------ | ------------------------------------------------ |
+| `h264_videotoolbox` | macOS         | Apple Silicon / Intel                                                                            | `--dataset.rgb_encoder.vcodec=h264_videotoolbox` |
+| `hevc_videotoolbox` | macOS         | Apple Silicon / Intel                                                                            | `--dataset.rgb_encoder.vcodec=hevc_videotoolbox` |
+| `h264_nvenc`        | Linux/Windows | NVIDIA GPU                                                                                       | `--dataset.rgb_encoder.vcodec=h264_nvenc`        |
+| `hevc_nvenc`        | Linux/Windows | NVIDIA GPU                                                                                       | `--dataset.rgb_encoder.vcodec=hevc_nvenc`        |
+| `h264_vaapi`        | Linux         | Intel/AMD GPU                                                                                    | `--dataset.rgb_encoder.vcodec=h264_vaapi`        |
+| `h264_qsv`          | Linux/Windows | Intel Quick Sync                                                                                 | `--dataset.rgb_encoder.vcodec=h264_qsv`          |
+| `auto`              | Any           | Probes the system for available HW encoders. Falls back to `libsvtav1` if no HW encoder is found | `--dataset.rgb_encoder.vcodec=auto`              |
 
 > [!NOTE]
 > In order to use the HW accelerated encoders you might need to upgrade your GPU drivers.
@@ -100,15 +100,15 @@ Use HW encoding when:
 
 ## 5. Troubleshooting
 
-| Symptom                                                            | Likely Cause                                 | Fix                                                                                                                                                                                                                                                                                                 |
-| ------------------------------------------------------------------ | -------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| System freezes or choppy robot movement or Rerun visualization lag | CPU starved (100% load usage)                | Close other apps, reduce encoding throughput, lower `encoder_threads`, use `h264`, use `display_data=False`. If the CPU continues to be at 100% then it might be insufficient for your setup, consider `--dataset.streaming_encoding=false` or HW encoding (`--dataset.camera_encoder.vcodec=auto`) |
-| "Encoder queue full" warnings or dropped frames in dataset         | Encoder can't keep up (Queue overflow)       | If CPU is not at 100%: Increase `encoder_threads`, increase `encoder_queue_maxsize` or use HW encoding (`--dataset.camera_encoder.vcodec=auto`).                                                                                                                                                    |
-| High RAM usage                                                     | Queue filling faster than encoding           | `encoder_threads` too low or CPU insufficient. Reduce `encoder_queue_maxsize` or use HW encoding                                                                                                                                                                                                    |
-| Large video files                                                  | Using HW encoder or H.264                    | Expected trade-off. Switch to `libsvtav1` if CPU allows                                                                                                                                                                                                                                             |
-| `save_episode()` still slow                                        | `streaming_encoding` is `False`              | Set `--dataset.streaming_encoding=true`                                                                                                                                                                                                                                                             |
-| Encoder thread crash                                               | Codec not available or invalid settings      | Check `vcodec` is installed, try `--dataset.camera_encoder.vcodec=auto`                                                                                                                                                                                                                             |
-| Recorded dataset is missing frames                                 | CPU/GPU starvation or occasional load spikes | If ~5% of frames are missing, your system is likely overloaded — follow the recommendations above. If fewer frames are missing (~2%), they are probably due to occasional transient load spikes (often at startup) and can be considered expected.                                                  |
+| Symptom                                                            | Likely Cause                                 | Fix                                                                                                                                                                                                                                                                                              |
+| ------------------------------------------------------------------ | -------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
+| System freezes or choppy robot movement or Rerun visualization lag | CPU starved (100% load usage)                | Close other apps, reduce encoding throughput, lower `encoder_threads`, use `h264`, use `display_data=False`. If the CPU continues to be at 100% then it might be insufficient for your setup, consider `--dataset.streaming_encoding=false` or HW encoding (`--dataset.rgb_encoder.vcodec=auto`) |
+| "Encoder queue full" warnings or dropped frames in dataset         | Encoder can't keep up (Queue overflow)       | If CPU is not at 100%: Increase `encoder_threads`, increase `encoder_queue_maxsize` or use HW encoding (`--dataset.rgb_encoder.vcodec=auto`).                                                                                                                                                    |
+| High RAM usage                                                     | Queue filling faster than encoding           | `encoder_threads` too low or CPU insufficient. Reduce `encoder_queue_maxsize` or use HW encoding                                                                                                                                                                                                 |
+| Large video files                                                  | Using HW encoder or H.264                    | Expected trade-off. Switch to `libsvtav1` if CPU allows                                                                                                                                                                                                                                          |
+| `save_episode()` still slow                                        | `streaming_encoding` is `False`              | Set `--dataset.streaming_encoding=true`                                                                                                                                                                                                                                                          |
+| Encoder thread crash                                               | Codec not available or invalid settings      | Check `vcodec` is installed, try `--dataset.rgb_encoder.vcodec=auto`                                                                                                                                                                                                                             |
+| Recorded dataset is missing frames                                 | CPU/GPU starvation or occasional load spikes | If ~5% of frames are missing, your system is likely overloaded — follow the recommendations above. If fewer frames are missing (~2%), they are probably due to occasional transient load spikes (often at startup) and can be considered expected.                                               |
 
 ## 6. Recommended Configurations
 
@@ -146,7 +146,7 @@ On very constrained systems, streaming encoding may compete too heavily with the
 # 2camsx 640x480x3 @30fps: Requires some tuning.
 
 # Use H.264, disable streaming, consider batching encoding
-lerobot-record --dataset.camera_encoder.vcodec=h264 --dataset.streaming_encoding=false ...
+lerobot-record --dataset.rgb_encoder.vcodec=h264 --dataset.streaming_encoding=false ...
 ```
 
 ## 7. Closing note

docs/source/using_dataset_tools.mdx

@@ -11,8 +11,9 @@ LeRobot provides several utilities for manipulating datasets:
 3. **Merge Datasets** - Combine multiple datasets into one. The datasets must have identical features, and episodes are concatenated in the order specified in `repo_ids`
 4. **Add Features** - Add new features to a dataset
 5. **Remove Features** - Remove features from a dataset
-6. **Convert to Video** - Convert image-based datasets to video format for efficient storage
-7. **Show the Info of Datasets** - Show the summary of datasets information such as number of episode etc.
+6. **Convert to Video** - Convert image-based datasets to video format for efficient storage (RGB and depth cameras are encoded with separate encoders)
+7. **Re-encode Videos** - Re-encode an existing video dataset's RGB and/or depth streams with new encoder settings
+8. **Show the Info of Datasets** - Show the summary of datasets information such as number of episode etc.
 
 The core implementation is in `lerobot.datasets.dataset_tools`.
 An example script detailing how to use the tools API is available in `examples/dataset/use_dataset_tools.py`.
@@ -117,10 +118,19 @@ lerobot-edit-dataset \
     --repo_id lerobot/pusht_image \
     --operation.type convert_image_to_video \
     --operation.output_dir outputs/pusht_video \
-    --operation.camera_encoder.vcodec libsvtav1 \
-    --operation.camera_encoder.pix_fmt yuv420p \
-    --operation.camera_encoder.g 2 \
-    --operation.camera_encoder.crf 30
+    --operation.rgb_encoder.vcodec libsvtav1 \
+    --operation.rgb_encoder.pix_fmt yuv420p \
+    --operation.rgb_encoder.g 2 \
+    --operation.rgb_encoder.crf 30
+
+# Convert a dataset that includes depth maps, customizing the depth encoder
+lerobot-edit-dataset \
+    --repo_id lerobot/pusht_image \
+    --operation.type convert_image_to_video \
+    --operation.output_dir outputs/pusht_video \
+    --operation.depth_encoder.depth_min 0.01 \
+    --operation.depth_encoder.depth_max 10.0 \
+    --operation.depth_encoder.use_log true
 
 # Convert only specific episodes
 lerobot-edit-dataset \
@@ -147,11 +157,42 @@ lerobot-edit-dataset \
 **Parameters:**
 
 - `output_dir`: Custom output directory (optional - by default uses `new_repo_id` or `{repo_id}_video`)
-- `camera_encoder`: Video encoder settings — all sub-fields accessible via `--operation.camera_encoder.<field>. See [Video Encoding Parameters](./video_encoding_parameters) for more details.
+- `rgb_encoder`: Video encoder settings applied to RGB cameras — all sub-fields accessible via `--operation.rgb_encoder.<field>`. See [Video Encoding Parameters](./video_encoding_parameters) for more details.
+- `depth_encoder`: Video encoder settings applied to depth-map cameras (e.g. from an Intel RealSense). In addition to the standard encoder fields it exposes the depth quantization knobs (`depth_min`, `depth_max`, `shift`, `use_log`), accessible via `--operation.depth_encoder.<field>`. These quantization settings are persisted to the dataset metadata so depth can be dequantized back to physical units on load. See the [Depth streams](./video_encoding_parameters#depth-streams) section for details.
 - `episode_indices`: List of specific episodes to convert (default: all episodes)
 - `num_workers`: Number of parallel workers for processing (default: 4)
 
-**Note:** The resulting dataset will be a proper LeRobotDataset with all cameras encoded as videos in the `videos/` directory, with parquet files containing only metadata (no raw image data). All episodes, stats, and tasks are preserved.
+**Note:** The resulting dataset will be a proper LeRobotDataset with all cameras encoded as videos in the `videos/` directory, with parquet files containing only metadata (no raw image data). Depth-map cameras are detected automatically and routed to the `depth_encoder`, while RGB cameras use the `rgb_encoder`. All episodes, stats, and tasks are preserved.
+
+#### Re-encode Videos
+
+Re-encode the videos of an existing video dataset with different encoder settings, without going back to raw frames. RGB videos use the `rgb_encoder` and depth videos use the `depth_encoder`. Provide only the encoder(s) you want to re-encode; the other stream type is left untouched.
+
+```bash
+# Re-encode all RGB videos with new settings (saves to lerobot/pusht_reencoded by default)
+lerobot-edit-dataset \
+    --repo_id lerobot/pusht \
+    --operation.type reencode_videos \
+    --operation.rgb_encoder.vcodec h264 \
+    --operation.rgb_encoder.pix_fmt yuv420p \
+    --operation.rgb_encoder.crf 23
+
+# Re-encode both RGB and depth videos in a dataset with depth maps
+lerobot-edit-dataset \
+    --repo_id lerobot/pusht_depth \
+    --operation.type reencode_videos \
+    --operation.rgb_encoder.vcodec h264 \
+    --operation.depth_encoder.crf 50
+```
+
+**Parameters:**
+
+- `rgb_encoder`: Encoder settings applied to every RGB video. Omit to skip re-encoding RGB videos.
+- `depth_encoder`: Encoder settings applied to every depth video. Omit to skip re-encoding depth videos.
+- `num_workers`: Number of parallel workers for processing.
+
+> [!NOTE]
+> When re-encoding depth videos, the existing depth quantization parameters (`depth_min`, `depth_max`, `shift`, `use_log`) and the `is_depth_map` flag are **preserved** — re-encoding only changes the codec/quality of the stored stream, not how depth is dequantized on load.
 
 ### Show the information of datasets
 

docs/source/video_encoding_parameters.mdx

@@ -2,15 +2,15 @@
 
 When video storage is enabled, LeRobot stores each camera stream as an **MP4** file instead of saving one image file per timestep. Video encoding compresses across time, which usually cuts dataset size and I/O compared to a pile of PNG, while keeping MP4 — a format every player and loader understands.
 
-Encoding frames into an MP4 is a full FFmpeg pipeline: choice of encoder, pixel format, GOP/keyframes, quality vs. speed, and optional extra encoder flags. Most of these knobs are user-tunable through `camera_encoder`, a nested `VideoEncoderConfig` (`lerobot.configs.video.VideoEncoderConfig`) passed through PyAV.
+Encoding frames into an MP4 is a full FFmpeg pipeline: choice of encoder, pixel format, GOP/keyframes, quality vs. speed, and optional extra encoder flags. Most of these knobs are user-tunable through `rgb_encoder`, a nested `RGBEncoderConfig` (`lerobot.configs.video.RGBEncoderConfig`) passed through PyAV.
 
-You can set these parameters from the CLI with `--dataset.camera_encoder.<field>` (e.g. with `lerobot-record` or `lerobot-rollout`). The same block applies to every camera video stream in that run.
+You can set these parameters from the CLI with `--dataset.rgb_encoder.<field>` (e.g. with `lerobot-record` or `lerobot-rollout`). The same block applies to every camera video stream in that run.
 
 <Tip>
-  Video storage must be on for `camera_encoder` to have any effect —
+  Video storage must be on for `rgb_encoder` to have any effect —
   `use_videos=True` in Python APIs, or `--dataset.video=true` on the CLI (the
-  recording default). With video off, inputs stay as images and `camera_encoder`
-  is ignored.
+  recording default). With video off, inputs stay as images and `rgb_encoder` is
+  ignored.
 </Tip>
 
 For details on **when** frames are written vs. encoded (streaming vs. post-episode), queues, and other top-level `--dataset.*` switches, see [Streaming Video Encoding](./streaming_video_encoding). For an encoding-parameter comparison and experiments, see the [video-benchmark Space](https://huggingface.co/spaces/lerobot/video-benchmark).
@@ -33,9 +33,9 @@ lerobot-record \
     --dataset.single_task="Grab the cube" \
     --dataset.streaming_encoding=true \
     --dataset.encoder_threads=2 \
-    --dataset.camera_encoder.vcodec=h264 \
-    --dataset.camera_encoder.preset=fast \
-    --dataset.camera_encoder.extra_options={"tune": "film", "profile:v": "high", "bf": 2} \
+    --dataset.rgb_encoder.vcodec=h264 \
+    --dataset.rgb_encoder.preset=fast \
+    --dataset.rgb_encoder.extra_options={"tune": "film", "profile:v": "high", "bf": 2} \
     --display_data=true
 ```
 
@@ -50,7 +50,7 @@ Only override these parameters if you have a specific reason to, and measure the
 
 </Tip>
 
-All flags below are prefixed with `--dataset.camera_encoder.` on the CLI.
+All flags below are prefixed with `--dataset.rgb_encoder.` on the CLI.
 
 | Parameter       | Type             | Default       | Description                                                                                                                                                                            |
 | --------------- | ---------------- | ------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
@@ -65,6 +65,77 @@ All flags below are prefixed with `--dataset.camera_encoder.` on the CLI.
 
 ---
 
+## Depth streams
+
+Depth maps (Intel RealSense, Reachy 2) are stored as their **own video streams** alongside the RGB streams. Raw depth (`uint16` millimetres or `float32` metres) can't survive an 8-bit codec, so LeRobot **quantizes** each map to a 12-bit code (`[0, 4095]`) — logarithmically by default, to match the `1/depth` error profile of depth sensors — then packs it into a high-bit-depth pixel format (`gray12le`) and encodes it with a 12-bit codec.
+
+```mermaid
+flowchart LR
+    A["Raw depth (uint16 mm / float32 m)"] --> B["Clip to depth_min, depth_max"]
+    B --> C["Quantize to 12-bit code 0–4095 (log or linear)"]
+    C --> D["Pack into gray12le"]
+    D --> E["Encode video (hevc Main 12)"]
+    E --> F[("MP4 + metadata: depth_min/max, shift, use_log")]
+    F -. "load time (depth_output_unit)" .-> G["Dequantize to mm or m"]
+
+    classDef input fill:#e3f2fd,stroke:#1565c0,color:#0d47a1;
+    classDef encode fill:#ede7f6,stroke:#5e35b1,color:#311b92;
+    classDef store fill:#fff8e1,stroke:#f9a825,color:#e65100;
+    classDef load fill:#e8f5e9,stroke:#2e7d32,color:#1b5e20;
+
+    class A input;
+    class B,C,D,E encode;
+    class F store;
+    class G load;
+```
+
+Configure the depth pipeline through a parallel **`depth_encoder`** block (`DepthEncoderConfig`). It shares every `RGBEncoderConfig` field (`vcodec`, `pix_fmt`, `crf`, …) and adds four quantizer knobs, set via `--dataset.depth_encoder.<field>`:
+
+```bash
+lerobot-record \
+    ... \
+    --dataset.depth_encoder.vcodec=hevc \
+    --dataset.depth_encoder.depth_min=0.05 \
+    --dataset.depth_encoder.depth_max=5.0 \
+    --dataset.depth_encoder.use_log=true
+```
+
+| Parameter       | Type    | Default                         | Description                                                                                                                            |
+| --------------- | ------- | ------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------- |
+| `vcodec`        | `str`   | `"hevc"`                        | HEVC Main 12 (a 12-bit-capable codec, MP4-compatible).                                                                                 |
+| `extra_options` | `dict`  | `{"x265-params": "lossless=1"}` | **Depth defaults to lossless** (exact round-trip); `crf` is ignored. Pass `extra_options={}` and set `crf` for a smaller lossy stream. |
+| `pix_fmt`       | `str`   | `"gray12le"`                    | Single-channel 12-bit pixel format used to carry the quantized codes.                                                                  |
+| `depth_min`     | `float` | `0.01`                          | Depth in metres mapped to quantum `0`. Values below are clipped on decode.                                                             |
+| `depth_max`     | `float` | `10.0`                          | Depth in metres mapped to quantum `4095`. Values above are clipped on decode.                                                          |
+| `shift`         | `float` | `3.5`                           | Pre-log offset (metres) used in logarithmic quantization for numerical stability near zero. Must satisfy `depth_min + shift > 0`.      |
+| `use_log`       | `bool`  | `True`                          | If `true`, quantize in log-space (recommended for typical depth sensors). Set to `false` for uniform/linear quantization.              |
+
+> [!TIP]
+> `depth_min`, `depth_max`, and `shift` are always interpreted in **metres**, regardless of the input depth's unit. Inputs are auto-detected: integer arrays (e.g. `uint16` millimetres straight from a RealSense) are treated as millimetres, floating arrays as metres.
+> Pick `depth_min` / `depth_max` to bracket the actual working range of your sensor — quanta outside that range saturate, which can crush detail at the boundaries.
+
+Depth features are flagged with `"is_depth_map": true` in `meta/info.json`, and their quantizer settings (`video.depth_min`, `video.depth_max`, `video.shift`, `video.use_log`) are persisted — which is what lets depth be **dequantized back to physical units** on load.
+
+### Output unit at load time
+
+`depth_encoder` is a **record-time** concern. The unit that depth maps are dequantized to on _load_ (e.g. during training) is set separately by the read-time flag `--dataset.depth_output_unit`:
+
+```bash
+lerobot-train \
+    --dataset.repo_id=<my_username>/<my_dataset_name> \
+    --dataset.depth_output_unit=m \
+    --policy.type=act
+```
+
+| Parameter           | Type  | Default | Description                                                                                  |
+| ------------------- | ----- | ------- | -------------------------------------------------------------------------------------------- |
+| `depth_output_unit` | `str` | `"mm"`  | Physical unit depth maps are dequantized to on load: `"mm"` (millimetres) or `"m"` (metres). |
+
+> [!TIP]
+> This is purely a decode-time presentation choice — it does **not** alter the stored video or its metadata, so the same dataset can be read as `mm` or `m` without re-encoding. It has no effect on datasets without depth cameras.
+
+---
+
 ## Persistence in dataset metadata
 
 After the first episode of a video stream is encoded, the encoder configuration is **persisted into the dataset metadata** (`meta/info.json`) under each video feature, alongside the values probed from the file itself. For a video feature `observation.images.<camera>`, the layout in `info.json` is:
@@ -82,7 +153,7 @@ After the first episode of a video stream is encoded, the encoder configuration
         "video.pix_fmt": "yuv420p",
         "video.fps": 30,
         "video.channels": 3,
-        "video.is_depth_map": false,
+        "is_depth_map": false,
         "video.g": 2,
         "video.crf": 30,
         "video.preset": "fast",
@@ -97,12 +168,12 @@ After the first episode of a video stream is encoded, the encoder configuration
 
 Two sources contribute to the `info` block:
 
-- **Stream-derived** (read back from the encoded MP4 with PyAV): `video.height`, `video.width`, `video.codec`, `video.pix_fmt`, `video.fps`, `video.channels`, `video.is_depth_map`, plus `audio.*` if an audio stream is present.
-- **Encoder-derived** (taken from `VideoEncoderConfig`): `video.g`, `video.crf`, `video.preset`, `video.fast_decode`, `video.video_backend`, `video.extra_options`.
+- **Stream-derived** (read back from the encoded MP4 with PyAV): `video.height`, `video.width`, `video.codec`, `video.pix_fmt`, `video.fps`, `video.channels`, `is_depth_map`, plus `audio.*` if an audio stream is present.
+- **Encoder-derived** (taken from `RGBEncoderConfig` or `DepthEncoderConfig`): `video.g`, `video.crf`, `video.preset`, `video.fast_decode`, `video.video_backend`, `video.extra_options`.
 
 <Tip>
   This block is populated **once**, from the **first** episode. It assumes every
-  episode in the dataset was encoded with the same `camera_encoder`. Changing
+  episode in the dataset was encoded with the same `rgb_encoder`. Changing
   encoder settings partway through a recording is not supported — the
   `info.json` will only reflect the parameters used for the first episode.
 </Tip>

docs/source/vlabench.mdx

@@ -165,7 +165,7 @@ lerobot-train \
   --output_dir=./outputs/smolvla_vlabench_primitive \
   --steps=100000 \
   --batch_size=4 \
-  --eval_freq=5000 \
+  --env_eval_freq=5000 \
   --eval.batch_size=1 \
   --eval.n_episodes=1 \
   --save_freq=10000

examples/lekiwi/evaluate.py

@@ -17,7 +17,7 @@
 import logging
 import time
 
-from lerobot.common.control_utils import init_keyboard_listener, predict_action
+from lerobot.common.control_utils import predict_action
 from lerobot.datasets import LeRobotDataset
 from lerobot.policies import make_pre_post_processors
 from lerobot.policies.act import ACTPolicy
@@ -26,6 +26,7 @@ from lerobot.processor import make_default_processors
 from lerobot.robots.lekiwi import LeKiwiClient, LeKiwiClientConfig
 from lerobot.utils.constants import ACTION, OBS_STR
 from lerobot.utils.feature_utils import build_dataset_frame, hw_to_dataset_features
+from lerobot.utils.keyboard_input import init_keyboard_listener
 from lerobot.utils.robot_utils import precise_sleep
 from lerobot.utils.utils import log_say
 from lerobot.utils.visualization_utils import init_rerun, log_rerun_data

examples/lekiwi/record.py

@@ -14,7 +14,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from lerobot.common.control_utils import init_keyboard_listener
 from lerobot.datasets import LeRobotDataset
 from lerobot.processor import make_default_processors
 from lerobot.robots.lekiwi import LeKiwiClient, LeKiwiClientConfig
@@ -23,6 +22,7 @@ from lerobot.teleoperators.keyboard import KeyboardTeleop, KeyboardTeleopConfig
 from lerobot.teleoperators.so_leader import SO100Leader, SO100LeaderConfig
 from lerobot.utils.constants import ACTION, OBS_STR
 from lerobot.utils.feature_utils import hw_to_dataset_features
+from lerobot.utils.keyboard_input import init_keyboard_listener
 from lerobot.utils.utils import log_say
 from lerobot.utils.visualization_utils import init_rerun
 

examples/phone_to_so100/evaluate.py

@@ -18,7 +18,7 @@ import logging
 import time
 
 from lerobot.cameras.opencv import OpenCVCameraConfig
-from lerobot.common.control_utils import init_keyboard_listener, predict_action
+from lerobot.common.control_utils import predict_action
 from lerobot.configs import FeatureType, PolicyFeature
 from lerobot.datasets import LeRobotDataset, aggregate_pipeline_dataset_features, create_initial_features
 from lerobot.model.kinematics import RobotKinematics
@@ -41,6 +41,7 @@ from lerobot.robots.so_follower.robot_kinematic_processor import (
 from lerobot.types import RobotAction, RobotObservation
 from lerobot.utils.constants import ACTION, OBS_STR
 from lerobot.utils.feature_utils import build_dataset_frame, combine_feature_dicts
+from lerobot.utils.keyboard_input import init_keyboard_listener
 from lerobot.utils.robot_utils import precise_sleep
 from lerobot.utils.utils import log_say
 from lerobot.utils.visualization_utils import init_rerun, log_rerun_data

examples/phone_to_so100/record.py

@@ -15,7 +15,6 @@
 # limitations under the License.
 
 from lerobot.cameras.opencv import OpenCVCameraConfig
-from lerobot.common.control_utils import init_keyboard_listener
 from lerobot.datasets import LeRobotDataset, aggregate_pipeline_dataset_features, create_initial_features
 from lerobot.model.kinematics import RobotKinematics
 from lerobot.processor import (
@@ -39,6 +38,7 @@ from lerobot.teleoperators.phone.config_phone import PhoneOS
 from lerobot.teleoperators.phone.phone_processor import MapPhoneActionToRobotAction
 from lerobot.types import RobotAction, RobotObservation
 from lerobot.utils.feature_utils import combine_feature_dicts
+from lerobot.utils.keyboard_input import init_keyboard_listener
 from lerobot.utils.utils import log_say
 from lerobot.utils.visualization_utils import init_rerun
 

examples/so100_to_so100_EE/evaluate.py

@@ -18,7 +18,7 @@ import logging
 import time
 
 from lerobot.cameras.opencv import OpenCVCameraConfig
-from lerobot.common.control_utils import init_keyboard_listener, predict_action
+from lerobot.common.control_utils import predict_action
 from lerobot.configs import FeatureType, PolicyFeature
 from lerobot.datasets import LeRobotDataset, aggregate_pipeline_dataset_features, create_initial_features
 from lerobot.model.kinematics import RobotKinematics
@@ -41,6 +41,7 @@ from lerobot.robots.so_follower.robot_kinematic_processor import (
 from lerobot.types import RobotAction, RobotObservation
 from lerobot.utils.constants import ACTION, OBS_STR
 from lerobot.utils.feature_utils import build_dataset_frame, combine_feature_dicts
+from lerobot.utils.keyboard_input import init_keyboard_listener
 from lerobot.utils.robot_utils import precise_sleep
 from lerobot.utils.utils import log_say
 from lerobot.utils.visualization_utils import init_rerun, log_rerun_data

examples/so100_to_so100_EE/record.py

@@ -16,7 +16,6 @@
 
 
 from lerobot.cameras.opencv import OpenCVCameraConfig
-from lerobot.common.control_utils import init_keyboard_listener
 from lerobot.datasets import LeRobotDataset, aggregate_pipeline_dataset_features, create_initial_features
 from lerobot.model.kinematics import RobotKinematics
 from lerobot.processor import (
@@ -36,6 +35,7 @@ from lerobot.scripts.lerobot_record import record_loop
 from lerobot.teleoperators.so_leader import SO100Leader, SO100LeaderConfig
 from lerobot.types import RobotAction, RobotObservation
 from lerobot.utils.feature_utils import combine_feature_dicts
+from lerobot.utils.keyboard_input import init_keyboard_listener
 from lerobot.utils.utils import log_say
 from lerobot.utils.visualization_utils import init_rerun
 

pyproject.toml

@@ -124,7 +124,7 @@ hardware = [
     "lerobot[deepdiff-dep]",
 ]
 viz = [
-    "rerun-sdk>=0.24.0,<0.27.0",
+    "rerun-sdk>=0.24.0,<0.34.0",
 ]
 # ── User-facing composite extras (map to CLI scripts) ─────
 # lerobot-record, lerobot-replay, lerobot-calibrate, lerobot-teleoperate, etc.
@@ -140,7 +140,14 @@ av-dep = ["av>=15.0.0,<16.0.0"]
 pygame-dep = ["pygame>=2.5.1,<2.7.0"]
 # NOTE: 0.9.16 links against liburdfdom_sensor.so.4, which is unavailable on Ubuntu 24.04
 # (noble ships urdfdom 3.x). Cap below 0.9.16 until system urdfdom 4.x is broadly available.
-placo-dep = ["placo>=0.9.6,<0.9.16"]
+#
+# NOTE: placo pulls in pin (Pinocchio), whose binary wheels dlopen specific cmeel sonames
+# (liburdfdom_sensor.so.4.0, libtinyxml2.so.10) but declare only `>=` floors on their cmeel
+# packages. The 2026-05-21 major bumps (cmeel-urdfdom 6.0.0 -> .so.6, cmeel-tinyxml2 11.0.0
+# -> .so.11) ship newer sonames, so left unpinned the resolver grabs them and `import placo`
+# fails at load with "liburdfdom_sensor.so.4.0: cannot open shared object file" (see #3755).
+# There is no cmeel-urdfdom 5.x; <5 selects the 4.x ABI the placo/pin wheels are built against.
+placo-dep = ["placo>=0.9.6,<0.9.16", "cmeel-urdfdom>=4,<5", "cmeel-tinyxml2<11"]
 transformers-dep = ["transformers>=5.4.0,<5.6.0"]
 grpcio-dep = ["grpcio>=1.73.1,<2.0.0", "protobuf>=6.31.1,<8.0.0"]
 accelerate-dep = ["accelerate>=1.14.0,<2.0.0"]
@@ -222,6 +229,10 @@ robometer = ["lerobot[transformers-dep]", "lerobot[qwen-vl-utils-dep]", "lerobot
 topreward = ["lerobot[transformers-dep]"]
 xvla = ["lerobot[transformers-dep]"]
 eo1 = ["lerobot[transformers-dep]", "lerobot[qwen-vl-utils-dep]"]
+fastwam = [
+    "lerobot[transformers-dep]",
+    "lerobot[diffusers-dep]",
+]
 hilserl = ["lerobot[transformers-dep]", "lerobot[dataset]", "gym-hil>=0.1.14,<0.2.0", "lerobot[grpcio-dep]", "lerobot[placo-dep]"]
 vla_jepa = ["lerobot[transformers-dep]", "lerobot[diffusers-dep]", "lerobot[qwen-vl-utils-dep]"]
 
@@ -301,6 +312,7 @@ all = [
     "lerobot[pi]",
     "lerobot[molmoact2]",
     "lerobot[smolvla]",
+    "lerobot[fastwam]",
     # "lerobot[groot]", TODO(Steven): Gr00t requires specific installation instructions for flash-attn
     "lerobot[xvla]",
     "lerobot[hilserl]",
@@ -437,7 +449,8 @@ default.extend-ignore-identifiers-re = [
     "is_compileable",
     "ROBOTIS",
     "OT_VALUE",
-    "VanderBilt"
+    "VanderBilt",
+    "seperated_timestep",
 ]
 
 # TODO: Uncomment when ready to use

src/lerobot/annotations/steerable_pipeline/frames.py

@@ -36,7 +36,7 @@ from typing import Any, Protocol
 import PIL.Image
 import torch
 
-from lerobot.configs.video import VideoEncoderConfig
+from lerobot.configs import RGBEncoderConfig
 from lerobot.datasets.video_utils import decode_video_frames, reencode_video
 
 from .reader import EpisodeRecord, snap_to_frame
@@ -164,7 +164,9 @@ class VideoFrameProvider:
         # only for video-stored cameras. Image-stored cameras (also in
         # ``camera_keys``) would KeyError, so restrict the list — and the
         # default — to video keys.
-        keys = list(self._meta.video_keys)
+        # Depth cameras are excluded from the annotation pipeline for now.
+        depth_keys = set(self._meta.depth_keys)
+        keys = [key for key in self._meta.video_keys if key not in depth_keys]
         # Last-resort fallback: if metadata didn't surface any video keys but
         # the caller explicitly named a camera (``--vlm.camera_key=...``),
         # trust them — the key is by definition known to exist on the dataset.
@@ -276,12 +278,12 @@ class VideoFrameProvider:
         from_timestamp = float(ep[f"videos/{self.camera_key}/from_timestamp"])
         to_timestamp = float(ep[f"videos/{self.camera_key}/to_timestamp"])
         src = self.root / self._meta.get_video_file_path(record.episode_index, self.camera_key)
-        encoder = VideoEncoderConfig(vcodec="h264", pix_fmt="yuv420p", g=None, crf=23, preset="ultrafast")
+        encoder = RGBEncoderConfig(vcodec="h264", pix_fmt="yuv420p", g=None, crf=23, preset="ultrafast")
         try:
             reencode_video(
                 src,
                 out_path,
-                camera_encoder=encoder,
+                video_encoder=encoder,
                 overwrite=True,
                 start_time_s=from_timestamp,
                 end_time_s=to_timestamp,

src/lerobot/async_inference/helpers.py

@@ -105,8 +105,9 @@ def raw_observation_to_observation(
 
 
 def prepare_image(image: torch.Tensor) -> torch.Tensor:
-    """Minimal preprocessing to turn int8 images to float32 in [0, 1], and create a memory-contiguous tensor"""
-    image = image.type(torch.float32) / 255
+    """Minimal preprocessing to turn RGB uint8 images to float32 in [0, 1], and create a memory-contiguous tensor"""
+    if image.dtype == torch.uint8:
+        image = image.type(torch.float32) / 255
     image = image.contiguous()
 
     return image

src/lerobot/cameras/opencv/camera_opencv.py

@@ -436,7 +436,7 @@ class OpenCVCamera(Camera):
         Internal loop run by the background thread for asynchronous reading.
 
         On each iteration:
-        1. Reads a color frame
+        1. Reads a color frame (blocking call)
         2. Stores result in latest_frame and updates timestamp (thread-safe)
         3. Sets new_frame_event to notify listeners
 
@@ -485,6 +485,8 @@ class OpenCVCamera(Camera):
 
         if self.thread is not None and self.thread.is_alive():
             self.thread.join(timeout=2.0)
+            if self.thread.is_alive():
+                logger.warning(f"{self} read thread did not terminate within timeout.")
 
         self.thread = None
         self.stop_event = None

src/lerobot/cameras/realsense/camera_realsense.py

@@ -128,6 +128,7 @@ class RealSenseCamera(Camera):
 
         self.fps = config.fps
         self.color_mode = config.color_mode
+        self.use_rgb = config.use_rgb
         self.use_depth = config.use_depth
         self.warmup_s = config.warmup_s
 
@@ -195,12 +196,15 @@ class RealSenseCamera(Camera):
         # NOTE(Steven/Caroline): Enforcing at least one second of warmup as RS cameras need a bit of time before the first read. If we don't wait, the first read from the warmup will raise.
         self.warmup_s = max(self.warmup_s, 1)
 
+        warmup_read = self.async_read if self.use_rgb else self.async_read_depth
         start_time = time.time()
         while time.time() - start_time < self.warmup_s:
-            self.async_read(timeout_ms=self.warmup_s * 1000)
+            warmup_read(timeout_ms=self.warmup_s * 1000)
             time.sleep(0.1)
         with self.frame_lock:
-            if self.latest_color_frame is None or self.use_depth and self.latest_depth_frame is None:
+            if (self.use_rgb and self.latest_color_frame is None) or (
+                self.use_depth and self.latest_depth_frame is None
+            ):
                 raise ConnectionError(f"{self} failed to capture frames during warmup.")
 
         logger.info(f"{self} connected.")
@@ -268,13 +272,13 @@ class RealSenseCamera(Camera):
             )
 
         if len(found_devices) > 1:
-            serial_numbers = [dev["serial_number"] for dev in found_devices]
+            serial_numbers = [dev["id"] for dev in found_devices]
             raise ValueError(
                 f"Multiple RealSense cameras found with name '{name}'. "
                 f"Please use a unique serial number instead. Found SNs: {serial_numbers}"
             )
 
-        serial_number = str(found_devices[0]["serial_number"])
+        serial_number = str(found_devices[0]["id"])
         return serial_number
 
     def _configure_rs_pipeline_config(self, rs_config: Any) -> None:
@@ -282,15 +286,17 @@ class RealSenseCamera(Camera):
         rs.config.enable_device(rs_config, self.serial_number)
 
         if self.width and self.height and self.fps:
-            rs_config.enable_stream(
-                rs.stream.color, self.capture_width, self.capture_height, rs.format.rgb8, self.fps
-            )
+            if self.use_rgb:
+                rs_config.enable_stream(
+                    rs.stream.color, self.capture_width, self.capture_height, rs.format.rgb8, self.fps
+                )
             if self.use_depth:
                 rs_config.enable_stream(
                     rs.stream.depth, self.capture_width, self.capture_height, rs.format.z16, self.fps
                 )
         else:
-            rs_config.enable_stream(rs.stream.color)
+            if self.use_rgb:
+                rs_config.enable_stream(rs.stream.color)
             if self.use_depth:
                 rs_config.enable_stream(rs.stream.depth)
 
@@ -298,8 +304,9 @@ class RealSenseCamera(Camera):
     def _configure_capture_settings(self) -> None:
         """Sets fps, width, and height from device stream if not already configured.
 
-        Uses the color stream profile to update unset attributes. Handles rotation by
-        swapping width/height when needed. Original capture dimensions are always stored.
+        Uses the color stream profile (or the depth stream profile when the color
+        stream is disabled) to update unset attributes. Handles rotation by swapping
+        width/height when needed. Original capture dimensions are always stored.
 
         Raises:
             DeviceNotConnectedError: If device is not connected.
@@ -308,7 +315,8 @@ class RealSenseCamera(Camera):
         if self.rs_profile is None:
             raise RuntimeError(f"{self}: rs_profile must be initialized before use.")
 
-        stream = self.rs_profile.get_stream(rs.stream.color).as_video_stream_profile()
+        rs_stream = rs.stream.color if self.use_rgb else rs.stream.depth
+        stream = self.rs_profile.get_stream(rs_stream).as_video_stream_profile()
 
         if self.fps is None:
             self.fps = stream.fps()
@@ -323,6 +331,14 @@ class RealSenseCamera(Camera):
                 self.width, self.height = actual_width, actual_height
                 self.capture_width, self.capture_height = actual_width, actual_height
 
+    def _read(self, read_depth: bool = False) -> NDArray[Any]:
+        """Shared helper for :meth:`read`/:meth:`read_depth`: wait for a fresh color or depth frame."""
+        if self.thread is None or not self.thread.is_alive():
+            raise RuntimeError(f"{self} read thread is not running.")
+
+        self.new_frame_event.clear()
+        return self._async_read(timeout_ms=10000, read_depth=read_depth)
+
     @check_if_not_connected
     def read_depth(self, timeout_ms: int = 200) -> NDArray[Any]:
         """
@@ -332,8 +348,8 @@ class RealSenseCamera(Camera):
         from the camera hardware via the RealSense pipeline.
 
         Returns:
-            np.ndarray: The depth map as a NumPy array (height, width)
-                  of type `np.uint16` (raw depth values in millimeters) and rotation.
+            np.ndarray: The depth map as a NumPy array (height, width, 1)
+                  of type `np.uint16` (raw depth values in millimeters).
 
         Raises:
             DeviceNotConnectedError: If the camera is not connected.
@@ -349,20 +365,7 @@ class RealSenseCamera(Camera):
                 f"Failed to capture depth frame '.read_depth()'. Depth stream is not enabled for {self}."
             )
 
-        if self.thread is None or not self.thread.is_alive():
-            raise RuntimeError(f"{self} read thread is not running.")
-
-        self.new_frame_event.clear()
-
-        _ = self.async_read(timeout_ms=10000)
-
-        with self.frame_lock:
-            depth_map = self.latest_depth_frame
-
-        if depth_map is None:
-            raise RuntimeError("No depth frame available. Ensure camera is streaming.")
-
-        return depth_map
+        return self._read(read_depth=True)
 
     def _read_from_hardware(self):
         if self.rs_pipeline is None:
@@ -405,12 +408,10 @@ class RealSenseCamera(Camera):
                 f"{self} read() timeout_ms parameter is deprecated and will be removed in future versions."
             )
 
-        if self.thread is None or not self.thread.is_alive():
-            raise RuntimeError(f"{self} read thread is not running.")
+        if not self.use_rgb:
+            raise RuntimeError(f"{self}: cannot read color — camera was configured with use_rgb=False.")
 
-        self.new_frame_event.clear()
-
-        frame = self.async_read(timeout_ms=10000)
+        frame = self._read()
 
         read_duration_ms = (time.perf_counter() - start_time) * 1e3
         logger.debug(f"{self} read took: {read_duration_ms:.1f}ms")
@@ -465,8 +466,8 @@ class RealSenseCamera(Camera):
         Internal loop run by the background thread for asynchronous reading.
 
         On each iteration:
-        1. Reads a color frame with 500ms timeout
-        2. Stores result in latest_frame and updates timestamp (thread-safe)
+        1. Reads a color/depth frame (blocking call with 10s timeout)
+        2. Stores result in latest_color_frame/latest_depth_frame and updates timestamp (thread-safe)
         3. Sets new_frame_event to notify listeners
 
         Stops on DeviceNotConnectedError, logs other errors and continues.
@@ -479,19 +480,24 @@ class RealSenseCamera(Camera):
         while not stop_event.is_set():
             try:
                 frame = self._read_from_hardware()
-                color_frame_raw = frame.get_color_frame()
-                color_frame = np.asanyarray(color_frame_raw.get_data())
-                processed_color_frame = self._postprocess_image(color_frame)
+
+                if self.use_rgb:
+                    color_frame_raw = frame.get_color_frame()
+                    color_frame = np.asanyarray(color_frame_raw.get_data())
+                    processed_color_frame = self._postprocess_image(color_frame)
 
                 if self.use_depth:
                     depth_frame_raw = frame.get_depth_frame()
                     depth_frame = np.asanyarray(depth_frame_raw.get_data())
                     processed_depth_frame = self._postprocess_image(depth_frame, depth_frame=True)
+                    if processed_depth_frame.ndim == 2:  # (H, W) -> (H, W, 1)
+                        processed_depth_frame = processed_depth_frame[..., np.newaxis]
 
                 capture_time = time.perf_counter()
 
                 with self.frame_lock:
-                    self.latest_color_frame = processed_color_frame
+                    if self.use_rgb:
+                        self.latest_color_frame = processed_color_frame
                     if self.use_depth:
                         self.latest_depth_frame = processed_depth_frame
                     self.latest_timestamp = capture_time
@@ -523,6 +529,8 @@ class RealSenseCamera(Camera):
 
         if self.thread is not None and self.thread.is_alive():
             self.thread.join(timeout=2.0)
+            if self.thread.is_alive():  # pragma: no cover
+                logger.warning(f"{self} read thread did not terminate within timeout.")
 
         self.thread = None
         self.stop_event = None
@@ -533,7 +541,26 @@ class RealSenseCamera(Camera):
             self.latest_timestamp = None
             self.new_frame_event.clear()
 
-    # NOTE(Steven): Missing implementation for depth for now
+    def _async_read(self, timeout_ms: float, read_depth: bool = False) -> NDArray[Any]:
+        """Shared helper for :meth:`async_read`/:meth:`async_read_depth`: return the latest buffered frame."""
+        if self.thread is None or not self.thread.is_alive():
+            raise RuntimeError(f"{self} read thread is not running.")
+
+        if not self.new_frame_event.wait(timeout=timeout_ms / 1000.0):
+            raise TimeoutError(
+                f"Timed out waiting for frame from camera {self} after {timeout_ms} ms. "
+                f"Read thread alive: {self.thread.is_alive()}."
+            )
+
+        with self.frame_lock:
+            frame = self.latest_depth_frame if read_depth else self.latest_color_frame
+            self.new_frame_event.clear()
+
+        if frame is None:
+            raise RuntimeError(f"Internal error: Event set but no frame available for {self}.")
+
+        return frame
+
     @check_if_not_connected
     def async_read(self, timeout_ms: float = 200) -> NDArray[Any]:
         """
@@ -558,25 +585,31 @@ class RealSenseCamera(Camera):
             RuntimeError: If the background thread died unexpectedly or another error occurs.
         """
 
+        if not self.use_rgb:
+            raise RuntimeError(f"{self}: cannot read color — camera was configured with use_rgb=False.")
+
+        return self._async_read(timeout_ms=timeout_ms)
+
+    def _read_latest(self, max_age_ms: int, read_depth: bool = False) -> NDArray[Any]:
+        """Shared helper for :meth:`read_latest`/:meth:`read_latest_depth`: peek the latest buffered frame."""
         if self.thread is None or not self.thread.is_alive():
             raise RuntimeError(f"{self} read thread is not running.")
 
-        if not self.new_frame_event.wait(timeout=timeout_ms / 1000.0):
-            raise TimeoutError(
-                f"Timed out waiting for frame from camera {self} after {timeout_ms} ms. "
-                f"Read thread alive: {self.thread.is_alive()}."
-            )
-
         with self.frame_lock:
-            frame = self.latest_color_frame
-            self.new_frame_event.clear()
+            frame = self.latest_depth_frame if read_depth else self.latest_color_frame
+            timestamp = self.latest_timestamp
 
-        if frame is None:
-            raise RuntimeError(f"Internal error: Event set but no frame available for {self}.")
+        if frame is None or timestamp is None:
+            raise RuntimeError(f"{self} has not captured any frames yet.")
+
+        age_ms = (time.perf_counter() - timestamp) * 1e3
+        if age_ms > max_age_ms:
+            raise TimeoutError(
+                f"{self} latest frame is too old: {age_ms:.1f} ms (max allowed: {max_age_ms} ms)."
+            )
 
         return frame
 
-    # NOTE(Steven): Missing implementation for depth for now
     @check_if_not_connected
     def read_latest(self, max_age_ms: int = 500) -> NDArray[Any]:
         """Return the most recent (color) frame captured immediately (Peeking).
@@ -593,24 +626,48 @@ class RealSenseCamera(Camera):
             DeviceNotConnectedError: If the camera is not connected.
             RuntimeError: If the camera is connected but has not captured any frames yet.
         """
+        if not self.use_rgb:
+            raise RuntimeError(f"{self}: cannot read color — camera was configured with use_rgb=False.")
 
-        if self.thread is None or not self.thread.is_alive():
-            raise RuntimeError(f"{self} read thread is not running.")
+        return self._read_latest(max_age_ms=max_age_ms)
 
-        with self.frame_lock:
-            frame = self.latest_color_frame
-            timestamp = self.latest_timestamp
+    @check_if_not_connected
+    def async_read_depth(self, timeout_ms: float = 200) -> NDArray[np.uint16]:
+        """Read the latest depth frame asynchronously, in millimeters.
 
-        if frame is None or timestamp is None:
-            raise RuntimeError(f"{self} has not captured any frames yet.")
+        Mirrors :meth:`async_read` but returns the depth stream rather than the
+        color stream. Output is ``np.uint16`` of shape ``(H, W, 1)``, where each
+        pixel is the distance from the sensor in millimeters.
 
-        age_ms = (time.perf_counter() - timestamp) * 1e3
-        if age_ms > max_age_ms:
-            raise TimeoutError(
-                f"{self} latest frame is too old: {age_ms:.1f} ms (max allowed: {max_age_ms} ms)."
-            )
+        Raises:
+            DeviceNotConnectedError: If the camera is not connected.
+            RuntimeError: If ``use_depth`` is ``False`` for this camera, or if
+                the background read thread is not running.
+            TimeoutError: If no frame becomes available within ``timeout_ms``.
+        """
+        if not self.use_depth:
+            raise RuntimeError(f"{self}: cannot read depth — camera was configured with use_depth=False.")
 
-        return frame
+        return self._async_read(timeout_ms=timeout_ms, read_depth=True)
+
+    @check_if_not_connected
+    def read_latest_depth(self, max_age_ms: int = 500) -> NDArray[Any]:
+        """Return the most recent depth frame in millimeters (peeking).
+
+        Non-blocking counterpart of :meth:`read_latest` for the depth stream.
+        Output is ``np.uint16`` of shape ``(H, W, 1)``, where each pixel is the
+        distance from the sensor in millimeters.
+
+        Raises:
+            DeviceNotConnectedError: If the camera is not connected.
+            RuntimeError: If ``use_depth`` is ``False`` for this camera, or if
+                no depth frame has been captured yet.
+            TimeoutError: If the latest depth frame is older than ``max_age_ms``.
+        """
+        if not self.use_depth:
+            raise RuntimeError(f"{self}: cannot read depth — camera was configured with use_depth=False.")
+
+        return self._read_latest(max_age_ms=max_age_ms, read_depth=True)
 
     def disconnect(self) -> None:
         """

src/lerobot/cameras/realsense/configuration_realsense.py

@@ -42,12 +42,14 @@ class RealSenseCameraConfig(CameraConfig):
         height: Requested frame height in pixels for the color stream.
         serial_number_or_name: Unique serial number or human-readable name to identify the camera.
         color_mode: Color mode for image output (RGB or BGR). Defaults to RGB.
+        use_rgb: Whether to enable the color stream. Defaults to True.
         use_depth: Whether to enable depth stream. Defaults to False.
         rotation: Image rotation setting (0°, 90°, 180°, or 270°). Defaults to no rotation.
         warmup_s: Time reading frames before returning from connect (in seconds)
 
     Note:
         - Either name or serial_number must be specified.
+        - At least one of `use_rgb` or `use_depth` must be enabled.
         - Depth stream configuration (if enabled) will use the same FPS as the color stream.
         - The actual resolution and FPS may be adjusted by the camera to the nearest supported mode.
         - For `fps`, `width` and `height`, either all of them need to be set, or none of them.
@@ -55,6 +57,7 @@ class RealSenseCameraConfig(CameraConfig):
 
     serial_number_or_name: str
     color_mode: ColorMode = ColorMode.RGB
+    use_rgb: bool = True
     use_depth: bool = False
     rotation: Cv2Rotation = Cv2Rotation.NO_ROTATION
     warmup_s: int = 1
@@ -63,6 +66,9 @@ class RealSenseCameraConfig(CameraConfig):
         self.color_mode = ColorMode(self.color_mode)
         self.rotation = Cv2Rotation(self.rotation)
 
+        if not self.use_rgb and not self.use_depth:
+            raise ValueError("At least one of `use_rgb` or `use_depth` must be enabled.")
+
         values = (self.fps, self.width, self.height)
         if any(v is not None for v in values) and any(v is None for v in values):
             raise ValueError(

src/lerobot/cameras/zmq/camera_zmq.py

@@ -293,6 +293,8 @@ class ZMQCamera(Camera):
 
         if self.thread is not None and self.thread.is_alive():
             self.thread.join(timeout=2.0)
+            if self.thread.is_alive():
+                logger.warning(f"{self} read thread did not terminate within timeout.")
 
         self.thread = None
         self.stop_event = None

src/lerobot/common/control_utils.py

@@ -17,12 +17,9 @@ from __future__ import annotations
 ########################################################################################
 # Utilities
 ########################################################################################
-import logging
 import time
-import traceback
 from contextlib import nullcontext
 from copy import copy
-from functools import cache
 from typing import TYPE_CHECKING, Any
 
 import numpy as np
@@ -43,34 +40,6 @@ from lerobot.robots import Robot
 from lerobot.types import PolicyAction
 
 
-@cache
-def is_headless():
-    """
-    Detects if the Python script is running in a headless environment (e.g., without a display).
-
-    This function attempts to import `pynput`, a library that requires a graphical environment.
-    If the import fails, it assumes the environment is headless. The result is cached to avoid
-    re-running the check.
-
-    Returns:
-        True if the environment is determined to be headless, False otherwise.
-    """
-    try:
-        import pynput  # noqa
-
-        return False
-    except Exception:
-        print(
-            "Error trying to import pynput. Switching to headless mode. "
-            "As a result, the video stream from the cameras won't be shown, "
-            "and you won't be able to change the control flow with keyboards. "
-            "For more info, see traceback below.\n"
-        )
-        traceback.print_exc()
-        print()
-        return True
-
-
 def predict_action(
     observation: dict[str, np.ndarray],
     policy: PreTrainedPolicy,
@@ -122,59 +91,6 @@ def predict_action(
     return action
 
 
-def init_keyboard_listener():
-    """
-    Initializes a non-blocking keyboard listener for real-time user interaction.
-
-    This function sets up a listener for specific keys (right arrow, left arrow, escape) to control
-    the program flow during execution, such as stopping recording or exiting loops. It gracefully
-    handles headless environments where keyboard listening is not possible.
-
-    Returns:
-        A tuple containing:
-        - The `pynput.keyboard.Listener` instance, or `None` if in a headless environment.
-        - A dictionary of event flags (e.g., `exit_early`) that are set by key presses.
-    """
-    # Allow to exit early while recording an episode or resetting the environment,
-    # by tapping the right arrow key '->'. This might require a sudo permission
-    # to allow your terminal to monitor keyboard events.
-    events = {}
-    events["exit_early"] = False
-    events["rerecord_episode"] = False
-    events["stop_recording"] = False
-
-    if is_headless():
-        logging.warning(
-            "Headless environment detected. On-screen cameras display and keyboard inputs will not be available."
-        )
-        listener = None
-        return listener, events
-
-    # Only import pynput if not in a headless environment
-    from pynput import keyboard
-
-    def on_press(key):
-        try:
-            if key == keyboard.Key.right:
-                print("Right arrow key pressed. Exiting loop...")
-                events["exit_early"] = True
-            elif key == keyboard.Key.left:
-                print("Left arrow key pressed. Exiting loop and rerecord the last episode...")
-                events["rerecord_episode"] = True
-                events["exit_early"] = True
-            elif key == keyboard.Key.esc:
-                print("Escape key pressed. Stopping data recording...")
-                events["stop_recording"] = True
-                events["exit_early"] = True
-        except Exception as e:
-            print(f"Error handling key press: {e}")
-
-    listener = keyboard.Listener(on_press=on_press)
-    listener.start()
-
-    return listener, events
-
-
 def sanity_check_dataset_name(repo_id, policy_cfg):
     """
     Validates the dataset repository name against the presence of a policy configuration.

src/lerobot/common/train_utils.py

@@ -15,6 +15,7 @@
 # limitations under the License.
 from pathlib import Path
 
+from huggingface_hub import HfApi, snapshot_download
 from torch.optim import Optimizer
 from torch.optim.lr_scheduler import LRScheduler
 
@@ -35,6 +36,7 @@ from lerobot.utils.constants import (
     TRAINING_STATE_DIR,
     TRAINING_STEP,
 )
+from lerobot.utils.hub import find_latest_hub_checkpoint
 from lerobot.utils.io_utils import load_json, write_json
 from lerobot.utils.random_utils import load_rng_state, save_rng_state
 
@@ -283,3 +285,61 @@ def load_fsdp_optimizer_state(model, optimizer, checkpoint_dir: Path) -> None:
     with FSDP.state_dict_type(model, StateDictType.FULL_STATE_DICT, state_cfg, optim_cfg):
         sharded_osd = FSDP.optim_state_dict_to_load(model=model, optim=optimizer, optim_state_dict=full_osd)
     optimizer.load_state_dict(sharded_osd)
+
+
+def push_checkpoint_to_hub(
+    checkpoint_dir: Path,
+    repo_id: str,
+    *,
+    private: bool | None = None,
+) -> None:
+    """Upload a saved checkpoint directory to the Hub under checkpoints/<name>/.
+
+    Called once per save step when save_checkpoint_to_hub is enabled, so a
+    timed-out or crashed run still leaves recoverable checkpoints on the Hub.
+    The model repo is created idempotently, and the commit is tagged with the
+    checkpoint step so a checkpoint can be recovered with
+    --policy.pretrained_revision=<step> instead of a commit sha.
+    """
+    api = HfApi()
+    api.create_repo(repo_id=repo_id, repo_type="model", private=private, exist_ok=True)
+    commit = api.upload_folder(
+        folder_path=str(checkpoint_dir),
+        repo_id=repo_id,
+        repo_type="model",
+        path_in_repo=f"checkpoints/{checkpoint_dir.name}",
+        commit_message=f"checkpoint {checkpoint_dir.name}",
+    )
+    api.create_tag(
+        repo_id=repo_id,
+        tag=checkpoint_dir.name,
+        revision=commit.oid,
+        repo_type="model",
+        exist_ok=True,
+    )
+
+
+def resolve_resume_checkpoint(repo_id: str, output_dir: Path) -> Path:
+    """Download the latest checkpoint of a Hub training repo into a local run dir.
+
+    The symmetric counterpart to `push_checkpoint_to_hub`: given a model repo holding
+    `checkpoints/<step>/{pretrained_model,training_state}` subtrees, download the highest-numbered step
+    into `output_dir/checkpoints/<step>/`, recreate the local `last` symlink, and return that local
+    checkpoint dir. Used to resume training from the Hub on a machine (or HF Jobs pod) that does not
+    have the original local run dir.
+    """
+    latest = find_latest_hub_checkpoint(repo_id)
+    if latest is None:
+        raise FileNotFoundError(
+            f"No checkpoint found in '{repo_id}' under '{CHECKPOINTS_DIR}/'. "
+            "Was the run trained with --save_checkpoint_to_hub?"
+        )
+    snapshot_download(
+        repo_id=repo_id,
+        repo_type="model",
+        allow_patterns=f"{latest}/*",
+        local_dir=str(output_dir),
+    )
+    checkpoint_dir = output_dir / latest
+    update_last_checkpoint(checkpoint_dir)
+    return checkpoint_dir

src/lerobot/configs/__init__.py

@@ -22,7 +22,7 @@ Import them directly: ``from lerobot.configs.train import TrainPipelineConfig``
 """
 
 from .dataset import DatasetRecordConfig
-from .default import DatasetConfig, EvalConfig, PeftConfig, WandBConfig
+from .default import DatasetConfig, EvalConfig, JobConfig, PeftConfig, WandBConfig
 from .policies import PreTrainedConfig
 from .recipe import MessageTurn, TrainingRecipe, load_recipe
 from .types import (
@@ -33,10 +33,15 @@ from .types import (
     RTCAttentionSchedule,
 )
 from .video import (
+    DEFAULT_DEPTH_UNIT,
     VALID_VIDEO_CODECS,
     VIDEO_ENCODER_INFO_KEYS,
+    DepthEncoderConfig,
+    RGBEncoderConfig,
     VideoEncoderConfig,
-    camera_encoder_defaults,
+    depth_encoder_defaults,
+    encoder_config_from_video_info,
+    rgb_encoder_defaults,
 )
 
 __all__ = [
@@ -50,6 +55,7 @@ __all__ = [
     "DatasetRecordConfig",
     "DatasetConfig",
     "EvalConfig",
+    "JobConfig",
     "MessageTurn",
     "PeftConfig",
     "PreTrainedConfig",
@@ -57,9 +63,15 @@ __all__ = [
     "WandBConfig",
     "load_recipe",
     "VideoEncoderConfig",
+    "RGBEncoderConfig",
+    "DepthEncoderConfig",
     # Defaults
-    "camera_encoder_defaults",
+    "rgb_encoder_defaults",
+    "depth_encoder_defaults",
+    # Factories
+    "encoder_config_from_video_info",
     # Constants
+    "DEFAULT_DEPTH_UNIT",
     "VALID_VIDEO_CODECS",
     "VIDEO_ENCODER_INFO_KEYS",
 ]

src/lerobot/configs/dataset.py

@@ -18,7 +18,7 @@ from dataclasses import dataclass, field
 from datetime import datetime
 from pathlib import Path
 
-from .video import VideoEncoderConfig, camera_encoder_defaults
+from .video import DepthEncoderConfig, RGBEncoderConfig, depth_encoder_defaults, rgb_encoder_defaults
 
 
 @dataclass
@@ -58,8 +58,10 @@ class DatasetRecordConfig:
     # Set to 1 for immediate encoding (default behavior), or higher for batched encoding
     video_encoding_batch_size: int = 1
     # Video encoder settings for camera MP4s (codec, quality, GOP, etc.). Tuned via CLI nested keys,
-    # e.g. ``--dataset.camera_encoder.vcodec=h264`` (see ``VideoEncoderConfig``).
-    camera_encoder: VideoEncoderConfig = field(default_factory=camera_encoder_defaults)
+    # e.g. ``--dataset.rgb_encoder.vcodec=h264`` (see ``RGBEncoderConfig``).
+    rgb_encoder: RGBEncoderConfig = field(default_factory=rgb_encoder_defaults)
+    # Video encoder settings for depth-map MP4s (codec, quality, GOP, etc.). Tuned via CLI nested keys.
+    depth_encoder: DepthEncoderConfig = field(default_factory=depth_encoder_defaults)
     # Enable streaming video encoding: encode frames in real-time during capture instead
     # of writing PNG images first. Makes save_episode() near-instant. More info in the documentation: https://huggingface.co/docs/lerobot/streaming_video_encoding
     streaming_encoding: bool = False

src/lerobot/configs/default.py

@@ -19,6 +19,8 @@ from dataclasses import dataclass, field
 from lerobot.transforms import ImageTransformsConfig
 from lerobot.utils.import_utils import get_safe_default_video_backend
 
+from .video import DEFAULT_DEPTH_UNIT, DEPTH_METER_UNIT, DEPTH_MILLIMETER_UNIT
+
 
 @dataclass
 class DatasetConfig:
@@ -35,12 +37,23 @@ class DatasetConfig:
     revision: str | None = None
     use_imagenet_stats: bool = True
     video_backend: str = field(default_factory=get_safe_default_video_backend)
-    # When True, video frames are returned as uint8 tensors (0-255) instead of float32 (0.0-1.0).
+    # When True, RGB video frames are returned as uint8 tensors (0-255) instead of float32 (0.0-1.0).
     # This reduces memory and speeds up DataLoader IPC. The training pipeline handles the conversion.
     return_uint8: bool = False
+    # Physical unit depth maps are dequantized to at load time: "mm" (millimeters) or "m" (metres).
+    # Has no effect on datasets without depth cameras.
+    depth_output_unit: str = DEFAULT_DEPTH_UNIT
     streaming: bool = False
+    # Fraction of episodes held out per task for offline evaluation (0.0 = disabled).
+    eval_split: float = 0.0
 
     def __post_init__(self) -> None:
+        if self.depth_output_unit not in (DEPTH_METER_UNIT, DEPTH_MILLIMETER_UNIT):
+            raise ValueError(
+                f"depth_output_unit must be '{DEPTH_METER_UNIT}' or '{DEPTH_MILLIMETER_UNIT}', got {self.depth_output_unit!r}"
+            )
+        if not (0.0 <= self.eval_split < 1.0):
+            raise ValueError(f"eval_split must be in [0.0, 1.0), got {self.eval_split}")
         if self.episodes is not None:
             if any(ep < 0 for ep in self.episodes):
                 raise ValueError(
@@ -73,8 +86,17 @@ class EvalConfig:
     # `use_async_envs` specifies whether to use asynchronous environments (multiprocessing).
     # Defaults to True; automatically downgraded to SyncVectorEnv when batch_size=1.
     use_async_envs: bool = True
+    # Whether to record eval rollouts as a LeRobot dataset on disk.
+    recording: bool = False
+    # If set, push recorded eval datasets to the Hub under this repo id (one repo per task,
+    # suffixed by task and env index). Requires recording=true.
+    recording_repo_id: str | None = None
+    # Whether the pushed recording repositories should be private.
+    recording_private: bool = False
 
     def __post_init__(self) -> None:
+        if self.recording_repo_id is not None and not self.recording:
+            raise ValueError("eval.recording_repo_id requires eval.recording=true.")
         if self.batch_size == 0:
             self.batch_size = self._auto_batch_size()
         if self.batch_size > self.n_episodes:
@@ -123,3 +145,35 @@ class PeftConfig:
     # If None, the PEFT library defaults to alpha=8, which may dampen high-rank adapters.
     # Common values are r (alpha == rank) or 2*r.
     lora_alpha: int | None = None
+
+
+@dataclass
+class JobConfig:
+    # Where training runs. None (omitted) or "local" runs on this machine.
+    # Any other value is an HF Jobs flavor and submits the run to HF Jobs.
+    # List available flavors + pricing with `hf jobs hardware` command.
+    target: str | None = None
+    # Runtime image for the remote job (ignored for local runs).
+    image: str = "huggingface/lerobot-gpu:latest"
+    # Max wall-clock for the remote job as an HF Jobs duration string (e.g. "2h").
+    # Defaults to "2d": We pass an explicit, generous cap instead. Set a smaller
+    # value to fail fast, or a larger one for long runs.
+    timeout: str | None = "2d"
+    # Submit and exit instead of streaming the job logs in the foreground.
+    detach: bool = False
+    # Extra tags attached to the HF job and to any dataset this run pushes to the
+    # Hub. A "lerobot" tag is always added; e.g. --job.tags '["lelab"]' adds more.
+    tags: list[str] = field(default_factory=list)
+
+    # Two entry points to the same predicate: the staticmethod tests a raw target string
+    # straight from argv (before any JobConfig exists, to decide dispatch early), while the
+    # property is the ergonomic accessor for code that already holds a config instance.
+    @staticmethod
+    def is_remote_target(target: str | None) -> bool:
+        """True when `target` names an HF Jobs flavor rather than a local run."""
+        return target not in (None, "local")
+
+    @property
+    def is_remote(self) -> bool:
+        """True when training should run on HF Jobs rather than this machine."""
+        return self.is_remote_target(self.target)

src/lerobot/configs/train.py

@@ -26,11 +26,12 @@ from huggingface_hub.errors import HfHubHTTPError
 
 from lerobot import envs
 from lerobot.optim import LRSchedulerConfig, OptimizerConfig
-from lerobot.utils.hub import HubMixin
+from lerobot.utils.constants import PRETRAINED_MODEL_DIR
+from lerobot.utils.hub import HubMixin, find_latest_hub_checkpoint
 from lerobot.utils.sample_weighting import SampleWeightingConfig
 
 from . import parser
-from .default import DatasetConfig, EvalConfig, PeftConfig, WandBConfig
+from .default import DatasetConfig, EvalConfig, JobConfig, PeftConfig, WandBConfig
 from .policies import PreTrainedConfig
 from .rewards import RewardModelConfig
 
@@ -83,10 +84,11 @@ class TrainPipelineConfig(HubMixin):
     # with the same value for `dir` its contents will be overwritten unless you set `resume` to true.
     output_dir: Path | None = None
     job_name: str | None = None
-    # Set `resume` to true to resume a previous run. In order for this to work, you will need to make sure
-    # `dir` is the directory of an existing run with at least one checkpoint in it.
-    # Note that when resuming a run, the default behavior is to use the configuration from the checkpoint,
-    # regardless of what's provided with the training command at the time of resumption.
+    # Set `resume` to true to resume a previous run. Pass `--config_path` pointing at either a local
+    # checkpoint's train_config.json or a Hub repo id holding `checkpoints/<step>/` subtrees (the
+    # latest checkpoint is downloaded and resumed from). Note that when resuming, the default behavior
+    # is to use the configuration from the checkpoint, regardless of what's provided with the training
+    # command at the time of resumption (CLI `--*` flags still override).
     resume: bool = False
     # `seed` is used for training (eg: model initialization, dataset shuffling)
     # AND for the evaluation environments.
@@ -100,8 +102,13 @@ class TrainPipelineConfig(HubMixin):
     prefetch_factor: int = 4
     persistent_workers: bool = True
     steps: int = 100_000
-    eval_freq: int = 20_000
+    # Run policy in the simulation environment every N steps to measure reward/success (0 = disabled).
+    env_eval_freq: int = 20_000
     log_freq: int = 200
+    # Compute eval loss on held-out episodes every N steps (0 = disabled). Requires eval_split > 0.
+    eval_steps: int = 0
+    # Cap on total eval samples, split uniformly across tasks (0 = use all held-out data).
+    max_eval_samples: int = 0
     tolerance_s: float = 1e-4
     save_checkpoint: bool = True
     # Checkpoint is saved every `save_freq` training iterations and after the last training step.
@@ -113,6 +120,13 @@ class TrainPipelineConfig(HubMixin):
     wandb: WandBConfig = field(default_factory=WandBConfig)
     peft: PeftConfig | None = None
 
+    # Where to run training (local default, or an HF Jobs flavor). See JobConfig.
+    job: JobConfig = field(default_factory=JobConfig)
+    # Push each saved checkpoint to the Hub (policy.repo_id) as it is written, not
+    # just the final model (useful to monitor progress mid-run). Optional; the
+    # final model is pushed regardless. Works the same locally and remotely.
+    save_checkpoint_to_hub: bool = False
+
     # Sample weighting configuration (e.g., for RA-BC training)
     sample_weighting: SampleWeightingConfig | None = None
 
@@ -132,10 +146,17 @@ class TrainPipelineConfig(HubMixin):
             return self.reward_model  # type: ignore[return-value]
         return self.policy  # type: ignore[return-value]
 
-    def validate(self) -> None:
-        # HACK: We parse again the cli args here to get the pretrained paths if there was some.
-        policy_path = parser.get_path_arg("policy")
+    def _resolve_pretrained_from_cli(self) -> None:
+        """Resolve the pretrained source passed on the CLI into a loaded config.
+
+        The pretrained paths (`--policy.path`, `--reward_model.path`) and
+        `--config_path` are only recoverable by re-reading the CLI args: draccus
+        has already consumed them by the time `validate()` runs, so they are not
+        reflected on `self`. Exactly one source applies, in priority order:
+        reward-model path, policy path, then resume.
+        """
         reward_model_path = parser.get_path_arg("reward_model")
+        policy_path = parser.get_path_arg("policy")
 
         if reward_model_path:
             cli_overrides = parser.get_cli_overrides("reward_model")
@@ -144,31 +165,54 @@ class TrainPipelineConfig(HubMixin):
             )
             self.reward_model.pretrained_path = str(Path(reward_model_path))
         elif policy_path:
-            yaml_overrides = parser.get_yaml_overrides("policy")
-            cli_overrides = parser.get_cli_overrides("policy") or []
-            self.policy = PreTrainedConfig.from_pretrained(
-                policy_path, cli_overrides=yaml_overrides + cli_overrides
-            )
+            overrides = parser.get_yaml_overrides("policy") + (parser.get_cli_overrides("policy") or [])
+            self.policy = PreTrainedConfig.from_pretrained(policy_path, cli_overrides=overrides)
             self.policy.pretrained_path = Path(policy_path)
         elif self.resume:
-            config_path = parser.parse_arg("config_path")
-            if not config_path:
-                raise ValueError(
-                    f"A config_path is expected when resuming a run. Please specify path to {TRAIN_CONFIG_NAME}"
-                )
+            self._resolve_resume_checkpoint()
 
-            if not Path(config_path).resolve().exists():
-                raise NotADirectoryError(
-                    f"{config_path=} is expected to be a local path. "
-                    "Resuming from the hub is not supported for now."
-                )
+    def _resolve_resume_checkpoint(self) -> None:
+        """Point the trainable config at the checkpoint named by `--config_path`.
 
+        `config_path` is either a local path (to a checkpoint's train_config.json or its
+        pretrained_model/ dir) or a Hub repo id. For a Hub repo, the latest checkpoint is downloaded
+        into a fresh local run dir and resumed from there. The download is skipped when dispatching to
+        an HF Job (`job.is_remote`): the pod performs it when it runs the resume locally, and
+        `submit_to_hf` resolves the source repo for the remote command.
+        """
+        config_path = parser.parse_arg("config_path")
+        if not config_path:
+            raise ValueError(
+                f"A config_path is expected when resuming a run. Please specify path to {TRAIN_CONFIG_NAME}"
+            )
+
+        if Path(config_path).resolve().exists():
             policy_dir = Path(config_path).parent
-            if self.policy is not None:
-                self.policy.pretrained_path = policy_dir
-            if self.reward_model is not None:
-                self.reward_model.pretrained_path = str(policy_dir)
             self.checkpoint_path = policy_dir.parent
+        elif self.job.is_remote:
+            return
+        else:
+            from lerobot.common.train_utils import resolve_resume_checkpoint
+
+            # `self.output_dir` was loaded from the checkpoint's config and points at the original
+            # run's (now-absent) local dir. Resume into a fresh local dir instead, unless the user
+            # passed --output_dir explicitly.
+            cli_output_dir = parser.parse_arg("output_dir")
+            if cli_output_dir:
+                self.output_dir = Path(cli_output_dir)
+            else:
+                now = dt.datetime.now()
+                self.output_dir = Path("outputs/train") / f"{now:%Y-%m-%d}/{now:%H-%M-%S}_resume"
+            self.checkpoint_path = resolve_resume_checkpoint(config_path, self.output_dir)
+            policy_dir = self.checkpoint_path / PRETRAINED_MODEL_DIR
+
+        if self.policy is not None:
+            self.policy.pretrained_path = policy_dir
+        if self.reward_model is not None:
+            self.reward_model.pretrained_path = str(policy_dir)
+
+    def validate(self) -> None:
+        self._resolve_pretrained_from_cli()
 
         if self.policy is None and self.reward_model is None:
             raise ValueError(
@@ -208,9 +252,22 @@ class TrainPipelineConfig(HubMixin):
             self.optimizer = active_cfg.get_optimizer_preset()
             self.scheduler = active_cfg.get_scheduler_preset()
 
-        if hasattr(active_cfg, "push_to_hub") and active_cfg.push_to_hub and not active_cfg.repo_id:
+        if self.eval_steps > 0 and self.dataset.eval_split == 0.0:
+            raise ValueError("eval_steps > 0 requires dataset.eval_split > 0.0 to hold out eval data.")
+
+        # Remote runs auto-generate the repo_id in submit_to_hf (the policy may only be
+        # resolved here, from --policy.path), so don't demand it up front for them.
+        if (
+            hasattr(active_cfg, "push_to_hub")
+            and active_cfg.push_to_hub
+            and not active_cfg.repo_id
+            and not self.job.is_remote
+        ):
             raise ValueError("'repo_id' argument missing. Please specify it to push the model to the hub.")
 
+        if self.save_checkpoint_to_hub and not (self.policy is not None and self.policy.repo_id):
+            raise ValueError("save_checkpoint_to_hub requires --policy.repo_id.")
+
     @classmethod
     def __get_path_fields__(cls) -> list[str]:
         """Keys for draccus pretrained-path loading."""
@@ -247,22 +304,30 @@ class TrainPipelineConfig(HubMixin):
         elif Path(model_id).is_file():
             config_file = model_id
         else:
+            dl_kwargs = {
+                "repo_id": model_id,
+                "revision": revision,
+                "cache_dir": cache_dir,
+                "force_download": force_download,
+                "proxies": proxies,
+                "resume_download": resume_download,
+                "token": token,
+                "local_files_only": local_files_only,
+            }
             try:
-                config_file = hf_hub_download(
-                    repo_id=model_id,
-                    filename=TRAIN_CONFIG_NAME,
-                    revision=revision,
-                    cache_dir=cache_dir,
-                    force_download=force_download,
-                    proxies=proxies,
-                    resume_download=resume_download,
-                    token=token,
-                    local_files_only=local_files_only,
-                )
+                config_file = hf_hub_download(filename=TRAIN_CONFIG_NAME, **dl_kwargs)
             except HfHubHTTPError as e:
-                raise FileNotFoundError(
-                    f"{TRAIN_CONFIG_NAME} not found on the HuggingFace Hub in {model_id}"
-                ) from e
+                # No root train_config.json: this is a repo of periodic checkpoints from an
+                # interrupted run. Fall back to the latest checkpoint's config so the run can be
+                # resumed straight from the repo with `--config_path=<repo>`.
+                latest = find_latest_hub_checkpoint(model_id, token=token, revision=revision)
+                if latest is None:
+                    raise FileNotFoundError(
+                        f"{TRAIN_CONFIG_NAME} not found on the HuggingFace Hub in {model_id}"
+                    ) from e
+                config_file = hf_hub_download(
+                    filename=f"{latest}/{PRETRAINED_MODEL_DIR}/{TRAIN_CONFIG_NAME}", **dl_kwargs
+                )
 
         cli_args = kwargs.pop("cli_args", [])
         # Legacy RA-BC migration only applies to framework-saved checkpoints (always JSON).

src/lerobot/configs/video.py

@@ -20,7 +20,7 @@ from __future__ import annotations
 
 import logging
 from dataclasses import dataclass, field
-from typing import Any
+from typing import Any, ClassVar, Self
 
 from lerobot.utils.import_utils import require_package
 
@@ -40,7 +40,6 @@ VALID_VIDEO_CODECS: frozenset[str] = frozenset({"h264", "hevc", "libsvtav1", "au
 # Aliases for legacy video codec names.
 VIDEO_CODECS_ALIASES: dict[str, str] = {"av1": "libsvtav1"}
 
-
 LIBSVTAV1_DEFAULT_PRESET: int = 12
 
 # Keys persisted under ``features[*]["info"]`` as ``video.<name>`` (from :class:`VideoEncoderConfig`).
@@ -52,40 +51,45 @@ VIDEO_ENCODER_INFO_KEYS: frozenset[str] = frozenset(
     f"video.{name}" for name in VIDEO_ENCODER_INFO_FIELD_NAMES
 )
 
+# Default depth quantization and encoding parameters.
+DEPTH_QUANT_BITS: int = 12
+DEPTH_QMAX: int = (1 << DEPTH_QUANT_BITS) - 1  # 4095
+
+DEFAULT_DEPTH_MIN: float = 0.01
+DEFAULT_DEPTH_MAX: float = 10.0
+DEFAULT_DEPTH_SHIFT: float = 3.5
+DEFAULT_DEPTH_USE_LOG: bool = True
+DEFAULT_DEPTH_PIX_FMT: str = "gray12le"
+
+DEPTH_METER_UNIT: str = "m"
+DEPTH_MILLIMETER_UNIT: str = "mm"
+DEFAULT_DEPTH_UNIT: str = DEPTH_MILLIMETER_UNIT
+
+# Depth-specific tuning fields persisted under ``features[*]["info"]`` as ``video.<name>``.
+DEPTH_ENCODER_INFO_FIELD_NAMES: frozenset[str] = frozenset({"depth_min", "depth_max", "shift", "use_log"})
+
 
 @dataclass
 class VideoEncoderConfig:
-    """Video encoder configuration.
+    """Video encoder configuration."""
 
-    Attributes:
-        vcodec: Video encoder name. ``"auto"`` is resolved during
-            construction (HW encoder if available, else ``libsvtav1``).
-        pix_fmt: Pixel format (e.g. ``"yuv420p"``).
-        g: GOP size (keyframe interval).
-        crf: Quality level — mapped to the native quality parameter of the
-            codec (``crf`` for software, ``qp`` for NVENC/VAAPI,
-            ``q:v`` for VideoToolbox, ``global_quality`` for QSV).
-        preset: Speed/quality preset. Accepted type is per-codec.
-        fast_decode: Fast-decode tuning. For ``libsvtav1`` this is a level (0-2)
-            embedded in ``svtav1-params``. For ``h264`` and ``hevc`` non-zero values
-            set ``tune=fastdecode``. Ignored for other codecs.
-        video_backend: Python to be used for encoding. Only ``"pyav"``
-            is currently supported.
-        extra_options: Free-form dictionary of additional video encoder options
-            (e.g. ``{"tune": "film", "profile:v": "high", "bf": 2}``).
-    """
-
-    vcodec: str = "libsvtav1"  # TODO(CarolinePascal): rename to codec ?
-    pix_fmt: str = "yuv420p"
-    g: int | None = 2
-    crf: int | float | None = 30
-    preset: int | str | None = None
-    fast_decode: int = 0
+    vcodec: str = "libsvtav1"  # Video codec name. "auto" picks a hardware codec if available, else libsvtav1.
+    pix_fmt: str = "yuv420p"  # Pixel format (e.g. yuv420p).
+    g: int | None = 2  # GOP size (keyframe interval).
+    crf: int | float | None = 30  # Quality level. Lower means better quality and larger files.
+    preset: int | str | None = None  # Speed/quality preset. Accepted values are codec-specific.
+    fast_decode: int = 0  # Fast-decode tuning. Accepted values are codec-specific, 0 disables it.
     # TODO(CarolinePascal): add torchcodec support + find a way to unify the
     # two backends (encoding and decoding).
-    video_backend: str = "pyav"
+    video_backend: str = "pyav"  # Encoding backend. Only "pyav" is currently supported.
+    # Extra codec options merged last, e.g. {"tune": "film"}.
     extra_options: dict[str, Any] = field(default_factory=dict)
 
+    # Source-data channel count this encoder is expected to handle. ``None``
+    # disables the pix_fmt channel-count check; concrete subclasses set it
+    # (3 for RGB, 1 for depth, etc.).
+    _DEFAULT_CHANNELS: ClassVar[int | None] = None
+
     def __post_init__(self) -> None:
         self.resolve_vcodec()
         # Empty-constructor ergonomics: ``VideoEncoderConfig()`` must "just work".
@@ -94,9 +98,9 @@ class VideoEncoderConfig:
         self.validate()
 
     @classmethod
-    def from_video_info(cls, video_info: dict | None) -> VideoEncoderConfig:
-        """Reconstruct a :class:`VideoEncoderConfig` from a video feature's ``info`` block.
-        Missing or ``None`` values fall back to the class defaults.
+    def _kwargs_from_video_info(cls, video_info: dict | None) -> dict[str, Any]:
+        """Parse the ``video.*`` keys of a feature ``info`` block into
+        constructor kwargs.
         """
         video_info = video_info or {}
         kwargs: dict[str, Any] = {}
@@ -115,7 +119,15 @@ class VideoEncoderConfig:
                 continue
             kwargs[field_name] = value
 
-        return cls(**kwargs)
+        return kwargs
+
+    @classmethod
+    def from_video_info(cls, video_info: dict | None) -> Self:
+        """Reconstruct an encoder config from a video feature's ``info`` block.
+
+        Missing or ``None`` values fall back to the class defaults.
+        """
+        return cls(**cls._kwargs_from_video_info(video_info))
 
     def detect_available_encoders(self, encoders: list[str] | str) -> list[str]:
         """Return the subset of available encoders based on the specified video backend.
@@ -138,7 +150,9 @@ class VideoEncoderConfig:
             require_package("av", extra="dataset")
             from lerobot.datasets import check_video_encoder_parameters_pyav
 
-            check_video_encoder_parameters_pyav(self.vcodec, self.pix_fmt, self.get_codec_options())
+            check_video_encoder_parameters_pyav(
+                self.vcodec, self.pix_fmt, self.get_codec_options(), channels=self._DEFAULT_CHANNELS
+            )
 
     def resolve_vcodec(self) -> None:
         """Check ``vcodec`` and, when it is ``"auto"``, pick a concrete encoder.
@@ -230,6 +244,79 @@ class VideoEncoderConfig:
         return opts
 
 
-def camera_encoder_defaults() -> VideoEncoderConfig:
-    """Return a :class:`VideoEncoderConfig` with RGB-camera defaults."""
-    return VideoEncoderConfig()
+@dataclass
+class RGBEncoderConfig(VideoEncoderConfig):
+    """Encoder configuration for RGB camera streams.
+
+    Identical to :class:`VideoEncoderConfig` but declares the 3-channel
+    source-data layout so ``pix_fmt`` is validated against RGB inputs.
+    """
+
+    _DEFAULT_CHANNELS: ClassVar[int] = 3
+
+
+def rgb_encoder_defaults() -> RGBEncoderConfig:
+    """Return a :class:`RGBEncoderConfig` with RGB-camera defaults."""
+    return RGBEncoderConfig()
+
+
+@dataclass
+class DepthEncoderConfig(VideoEncoderConfig):
+    """Encoder configuration for depth-map streams.
+
+    Inherits the full :class:`VideoEncoderConfig` surface (codec, GOP, CRF,
+    preset, ``extra_options``…) and adds the parameters of the depth quantizer.
+    Defaults flip ``vcodec`` to ``"hevc"`` (Main 12 profile) and ``pix_fmt`` to
+    ``"gray12le"``.
+    """
+
+    vcodec: str = "hevc"  # Video codec name. Defaults to HEVC Main 12 (a 12-bit-capable codec).
+    pix_fmt: str = "gray12le"  # Pixel format. Defaults to 12-bit grayscale.
+    extra_options: dict[str, Any] = field(default_factory=lambda: {"x265-params": "lossless=1"})
+
+    depth_min: float = DEFAULT_DEPTH_MIN  # Minimum depth in meters, mapped to the lowest quantum.
+    depth_max: float = DEFAULT_DEPTH_MAX  # Maximum depth in meters, mapped to the highest quantum.
+    shift: float = DEFAULT_DEPTH_SHIFT  # Pre-log offset in meters for numerical stability near zero.
+    use_log: bool = DEFAULT_DEPTH_USE_LOG  # Use logarithmic quantization (True) or linear (False).
+
+    _DEFAULT_CHANNELS: ClassVar[int] = 1
+
+    @classmethod
+    def _kwargs_from_video_info(cls, video_info: dict | None) -> dict[str, Any]:
+        """Layer the depth-specific tuning (``depth_min`` / ``depth_max`` /
+        ``shift`` / ``use_log``) on top of the base parser. Missing keys
+        fall back to the class defaults.
+        """
+        kwargs = super()._kwargs_from_video_info(video_info)
+        video_info = video_info or {}
+        for name in DEPTH_ENCODER_INFO_FIELD_NAMES:
+            value = video_info.get(f"video.{name}")
+            if value is not None:
+                kwargs[name] = value
+        return kwargs
+
+
+def depth_encoder_defaults() -> DepthEncoderConfig:
+    """Return a :class:`DepthEncoderConfig` with depth-camera defaults."""
+    return DepthEncoderConfig()
+
+
+def encoder_config_from_video_info(video_info: dict | None) -> VideoEncoderConfig:
+    """Build the appropriate encoder config from a feature's ``info`` block.
+
+    Dispatches to :class:`DepthEncoderConfig` when the dict marks the feature
+    as a depth map and to :class:`RGBEncoderConfig`
+    otherwise.
+
+    Args:
+        video_info: A feature's ``info`` dict as persisted in ``info.json``,
+            or ``None`` (treated as an empty dict).
+
+    Returns:
+        A :class:`DepthEncoderConfig` for depth features, otherwise a
+        :class:`RGBEncoderConfig`.
+    """
+    video_info = video_info or {}
+    is_depth = bool(video_info.get("is_depth_map") or video_info.get("video.is_depth_map"))
+    cls: type[VideoEncoderConfig] = DepthEncoderConfig if is_depth else RGBEncoderConfig
+    return cls.from_video_info(video_info)

src/lerobot/datasets/__init__.py

@@ -35,7 +35,7 @@ from .dataset_tools import (
     remove_feature,
     split_dataset,
 )
-from .factory import make_dataset, resolve_delta_timestamps
+from .factory import make_dataset, make_train_eval_datasets, resolve_delta_timestamps
 from .image_writer import safe_stop_image_writer
 from .io_utils import load_episodes, write_stats
 from .language import (
@@ -89,6 +89,7 @@ __all__ = [
     "get_feature_stats",
     "load_episodes",
     "make_dataset",
+    "make_train_eval_datasets",
     "merge_datasets",
     "modify_features",
     "modify_tasks",

src/lerobot/datasets/compute_stats.py

@@ -242,12 +242,12 @@ def sample_images(image_paths: list[str]) -> np.ndarray:
     images = None
     for i, idx in enumerate(sampled_indices):
         path = image_paths[idx]
-        # we load as uint8 to reduce memory usage
+        # we load RGB images as uint8 to reduce memory usage; depth keeps its native dtype
         img = load_image_as_numpy(path, dtype=np.uint8, channel_first=True)
         img = auto_downsample_height_width(img)
 
         if images is None:
-            images = np.empty((len(sampled_indices), *img.shape), dtype=np.uint8)
+            images = np.empty((len(sampled_indices), *img.shape), dtype=img.dtype)
 
         images[i] = img
 
@@ -506,8 +506,10 @@ def compute_episode_stats(
         Each statistics dictionary contains min, max, mean, std, count, and quantiles.
 
     Note:
-        Image statistics are normalized to [0,1] range and have shape (3,1,1) for
-        per-channel values when dtype is 'image' or 'video'.
+        For 'image'/'video' features, stats are computed per channel and kept with a
+        leading channel axis (e.g. shape (3, 1, 1) for RGB). RGB stats are divided by
+        255 to land in [0, 1]; depth maps (features flagged with ``is_depth_map``) skip
+        this rescaling and remain in their stored units.
     """
     if quantile_list is None:
         quantile_list = DEFAULT_QUANTILES
@@ -531,8 +533,12 @@ def compute_episode_stats(
         )
 
         if features[key]["dtype"] in ["image", "video"]:
+            normalization_factor = (
+                255.0 if not (features[key].get("info") or {}).get("is_depth_map", False) else 1.0
+            )
             ep_stats[key] = {
-                k: v if k == "count" else np.squeeze(v / 255.0, axis=0) for k, v in ep_stats[key].items()
+                k: v if k == "count" else np.squeeze(v / normalization_factor, axis=0)
+                for k, v in ep_stats[key].items()
             }
 
     return ep_stats
@@ -552,8 +558,10 @@ def _validate_stat_value(value: np.ndarray, key: str, feature_key: str) -> None:
     if key == "count" and value.shape != (1,):
         raise ValueError(f"Shape of 'count' must be (1), but is {value.shape} instead.")
 
-    if "image" in feature_key and key != "count" and value.shape != (3, 1, 1):
-        raise ValueError(f"Shape of quantile '{key}' must be (3,1,1), but is {value.shape} instead.")
+    if "image" in feature_key and key != "count" and value.shape not in ((3, 1, 1), (1, 1, 1)):
+        raise ValueError(
+            f"Shape of quantile '{key}' must be (3,1,1) or (1,1,1) but is {value.shape} instead."
+        )
 
 
 def _assert_type_and_shape(stats_list: list[dict[str, dict]]):

src/lerobot/datasets/dataset_metadata.py

@@ -14,7 +14,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import contextlib
-from collections.abc import Callable
+import logging
+from collections.abc import Callable, Iterable
 from copy import deepcopy
 from pathlib import Path
 
@@ -338,6 +339,25 @@ class LeRobotDatasetMetadata:
         """Keys to access visual modalities stored as videos."""
         return [key for key, ft in self.features.items() if ft["dtype"] == "video"]
 
+    @property
+    def depth_keys(self) -> list[str]:
+        """Keys to access depth-map modalities stored as videos or images.
+
+        A depth key is a feature whose ``info`` dict carries ``"is_depth_map": True``
+        (or the legacy ``"video.is_depth_map"`` inside ``info`` or ``video_info``).
+        """
+
+        def _is_depth(ft: dict) -> bool:
+            info = ft.get("info") or {}
+            video_info = ft.get("video_info") or {}
+            return (
+                info.get("is_depth_map", False)
+                or info.get("video.is_depth_map", False)
+                or video_info.get("video.is_depth_map", False)
+            )
+
+        return [key for key, ft in self.features.items() if _is_depth(ft)]
+
     @property
     def camera_keys(self) -> list[str]:
         """Keys to access visual modalities (regardless of their storage method)."""
@@ -581,29 +601,48 @@ class LeRobotDatasetMetadata:
     def update_video_info(
         self,
         video_key: str | None = None,
-        camera_encoder: VideoEncoderConfig | None = None,
+        video_encoder: VideoEncoderConfig | None = None,
+        preserve_keys: Iterable[str] | None = None,
     ) -> None:
-        """Populate per-feature video info in ``info.json``.
+        """Populate or refresh per-feature video info in ``info.json``.
 
         Warning: this function writes info from first episode videos, implicitly assuming that all videos have
         been encoded the same way. Also, this means it assumes the first episode exists.
 
+        Always re-probes the videos and overwrites existing info for every recomputed
+        key. ``preserve_keys`` lists keys whose existing values must be kept (e.g.
+        data-intrinsic entries like ``is_depth_map`` and depth quantization params)
+        instead of being recomputed.
+
         Args:
             video_key: If provided, only update this video key. Otherwise update
                 all video keys in the dataset.
-            camera_encoder: Encoder configuration used to produce the
+            video_encoder: Encoder configuration used to produce the
                 videos. When provided, its fields are recorded as
                 ``video.<field>`` entries alongside the stream-derived
                 ``video.*`` entries (see :func:`get_video_info`).
+            preserve_keys: Keys whose existing values are kept instead of being
+                recomputed. ``None`` (default) recomputes every key.
         """
         if video_key is not None and video_key not in self.video_keys:
             raise ValueError(f"Video key {video_key} not found in dataset")
 
         video_keys = [video_key] if video_key is not None else self.video_keys
+        preserve_set = set(preserve_keys or ())
         for key in video_keys:
-            if not self.features[key].get("info", None):
-                video_path = self.root / self.video_path.format(video_key=key, chunk_index=0, file_index=0)
-                self.info.features[key]["info"] = get_video_info(video_path, camera_encoder=camera_encoder)
+            existing = self.features[key].get("info") or {}
+            video_path = self.root / self.video_path.format(video_key=key, chunk_index=0, file_index=0)
+            new_info = get_video_info(video_path, video_encoder=video_encoder)
+            # Drop preserved keys so the existing values win on merge.
+            new_info = {k: v for k, v in new_info.items() if k not in preserve_set}
+            merged = {**existing, **new_info}
+            # Migrate the legacy depth marker to the canonical key.
+            if "video.is_depth_map" in merged:
+                logging.warning(
+                    f"Migrating legacy 'video.is_depth_map' to 'is_depth_map' for feature {key!r}."
+                )
+                merged.setdefault("is_depth_map", merged.pop("video.is_depth_map"))
+            self.info.features[key]["info"] = merged
 
     def update_chunk_settings(
         self,

src/lerobot/datasets/dataset_reader.py

@@ -22,7 +22,10 @@ from pathlib import Path
 import datasets
 import torch
 
+from lerobot.configs import DEFAULT_DEPTH_UNIT, DepthEncoderConfig
+
 from .dataset_metadata import LeRobotDatasetMetadata
+from .depth_utils import dequantize_depth
 from .feature_utils import (
     check_delta_timestamps,
     get_delta_indices,
@@ -51,6 +54,7 @@ class DatasetReader:
         delta_timestamps: dict[str, list[float]] | None,
         image_transforms: Callable | None,
         return_uint8: bool = False,
+        depth_output_unit: str = DEFAULT_DEPTH_UNIT,
     ):
         """Initialize the reader with metadata, filtering, and transform config.
 
@@ -68,6 +72,10 @@ class DatasetReader:
                 relative timestamp offsets for temporal context windows.
             image_transforms: Optional torchvision v2 transform applied to
                 visual features.
+            return_uint8: If True, return RGB video frames as raw uint8 tensors
+                instead of normalized float32.
+            depth_output_unit: Physical unit depth maps are dequantized to
+                (``"m"`` or ``"mm"``). Defaults to ``"mm"``.
         """
         self._meta = meta
         self.root = root
@@ -78,6 +86,7 @@ class DatasetReader:
             raise TypeError("image_transforms must be callable or None.")
         self._image_transforms = image_transforms
         self._return_uint8 = return_uint8
+        self._depth_output_unit = depth_output_unit
 
         self.hf_dataset: datasets.Dataset | None = None
         self._absolute_to_relative_idx: dict[int, int] | None = None
@@ -88,6 +97,11 @@ class DatasetReader:
             check_delta_timestamps(delta_timestamps, meta.fps, tolerance_s)
             self.delta_indices = get_delta_indices(delta_timestamps, meta.fps)
 
+        self._depth_encoder_configs: dict[str, DepthEncoderConfig] = {
+            vid_key: DepthEncoderConfig.from_video_info(self._meta.features[vid_key].get("info"))
+            for vid_key in self._meta.depth_keys
+        }
+
     def set_image_transforms(self, image_transforms: Callable | None) -> None:
         """Replace the transform applied to visual observations."""
         if image_transforms is not None and not callable(image_transforms):
@@ -259,7 +273,18 @@ class DatasetReader:
                 self._tolerance_s,
                 self._video_backend,
                 return_uint8=self._return_uint8,
+                is_depth=vid_key in self._meta.depth_keys,
             )
+            if vid_key in self._meta.depth_keys:
+                depth_encoder = self._depth_encoder_configs[vid_key]
+                frames = dequantize_depth(
+                    frames,
+                    depth_min=depth_encoder.depth_min,
+                    depth_max=depth_encoder.depth_max,
+                    shift=depth_encoder.shift,
+                    use_log=depth_encoder.use_log,
+                    output_unit=self._depth_output_unit,
+                )
             return vid_key, frames.squeeze(0)
 
         items = list(query_timestamps.items())
@@ -299,8 +324,9 @@ class DatasetReader:
             item = {**video_frames, **item}
 
         if self._image_transforms is not None:
-            image_keys = self._meta.camera_keys
-            for cam in image_keys:
+            for cam in self._meta.camera_keys:
+                if cam in self._meta.depth_keys:
+                    continue
                 item[cam] = self._image_transforms(item[cam])
 
         # Add task as a string

src/lerobot/datasets/dataset_tools.py

@@ -37,7 +37,15 @@ import pyarrow.parquet as pq
 import torch
 from tqdm import tqdm
 
-from lerobot.configs import VideoEncoderConfig, camera_encoder_defaults
+from lerobot.configs import (
+    DepthEncoderConfig,
+    RGBEncoderConfig,
+    VideoEncoderConfig,
+    depth_encoder_defaults,
+    encoder_config_from_video_info,
+    rgb_encoder_defaults,
+)
+from lerobot.configs.video import DEPTH_ENCODER_INFO_FIELD_NAMES
 from lerobot.utils.constants import ACTION, HF_LEROBOT_HOME, OBS_IMAGE, OBS_STATE
 from lerobot.utils.utils import flatten_dict
 
@@ -48,6 +56,7 @@ from .compute_stats import (
     compute_relative_action_stats,
 )
 from .dataset_metadata import LeRobotDatasetMetadata
+from .image_writer import write_image
 from .io_utils import (
     get_parquet_file_size_in_mb,
     load_episodes,
@@ -62,12 +71,13 @@ from .utils import (
     DEFAULT_DATA_FILE_SIZE_IN_MB,
     DEFAULT_DATA_PATH,
     DEFAULT_EPISODES_PATH,
+    DEPTH_FILE_PATTERN,
+    IMAGE_FILE_PATTERN,
     VIDEO_DIR,
     update_chunk_file_indices,
 )
 from .video_utils import (
     encode_video_frames,
-    get_video_info,
     reencode_video,
 )
 
@@ -601,7 +611,7 @@ def _keep_episodes_from_video_with_av(
     output_path: Path,
     episodes_to_keep: list[tuple[int, int]],
     fps: float,
-    camera_encoder: VideoEncoderConfig,
+    video_encoder: VideoEncoderConfig,
 ) -> None:
     """Keep only specified episodes from a video file using PyAV.
 
@@ -615,7 +625,7 @@ def _keep_episodes_from_video_with_av(
             Ranges are half-open intervals: [start_frame, end_frame), where start_frame
             is inclusive and end_frame is exclusive.
         fps: Frame rate of the video.
-        camera_encoder: Video encoder settings used to re-encode the kept frames.
+        video_encoder: Video encoder settings used to re-encode the kept frames.
     """
     from fractions import Fraction
 
@@ -640,13 +650,13 @@ def _keep_episodes_from_video_with_av(
 
     # Convert fps to Fraction for PyAV compatibility.
     fps_fraction = Fraction(fps).limit_denominator(1000)
-    codec_options = camera_encoder.get_codec_options(as_strings=True)
-    v_out = out.add_stream(camera_encoder.vcodec, rate=fps_fraction, options=codec_options)
+    codec_options = video_encoder.get_codec_options(as_strings=True)
+    v_out = out.add_stream(video_encoder.vcodec, rate=fps_fraction, options=codec_options)
 
     # PyAV type stubs don't distinguish video streams from audio/subtitle streams.
     v_out.width = v_in.codec_context.width
     v_out.height = v_in.codec_context.height
-    v_out.pix_fmt = camera_encoder.pix_fmt
+    v_out.pix_fmt = video_encoder.pix_fmt
 
     # Set time_base to match the frame rate for proper timestamp handling.
     v_out.time_base = Fraction(1, int(fps))
@@ -733,7 +743,7 @@ def _copy_and_reindex_videos(
 
     for video_key in src_dataset.meta.video_keys:
         logging.info(f"Processing videos for {video_key}")
-        camera_encoder = VideoEncoderConfig.from_video_info(
+        video_encoder = encoder_config_from_video_info(
             src_dataset.meta.info.features.get(video_key, {}).get("info")
         )
 
@@ -817,7 +827,7 @@ def _copy_and_reindex_videos(
                     dst_video_path,
                     episodes_to_keep_ranges,
                     src_dataset.meta.fps,
-                    camera_encoder,
+                    video_encoder,
                 )
 
                 cumulative_ts = 0.0
@@ -874,11 +884,11 @@ def _copy_and_reindex_episodes_metadata(
             episode_meta.update(video_metadata[new_idx])
 
         # Extract episode statistics from parquet metadata.
-        # Note (maractingi): When pandas/pyarrow serializes numpy arrays with shape (3, 1, 1) to parquet,
+        # When pandas/pyarrow serializes numpy arrays with shape (C, 1, 1) to parquet,
         # they are being deserialized as nested object arrays like:
         #   array([array([array([0.])]), array([array([0.])]), array([array([0.])])])
         # This happens particularly with image/video statistics. We need to detect and flatten
-        # these nested structures back to proper (3, 1, 1) arrays so aggregate_stats can process them.
+        # these nested structures back to proper (C, 1, 1) arrays so aggregate_stats can process them.
         episode_stats = {}
         for key in src_episode_full:
             if key.startswith("stats/"):
@@ -894,15 +904,16 @@ def _copy_and_reindex_episodes_metadata(
                     if feature_name in src_dataset.meta.features:
                         feature_dtype = src_dataset.meta.features[feature_name]["dtype"]
                         if feature_dtype in ["image", "video"] and stat_name != "count":
+                            # Stats are channel-first (C, 1, 1)
                             if isinstance(value, np.ndarray) and value.dtype == object:
                                 flat_values = []
                                 for item in value:
                                     while isinstance(item, np.ndarray):
                                         item = item.flatten()[0]
                                     flat_values.append(item)
-                                value = np.array(flat_values, dtype=np.float64).reshape(3, 1, 1)
-                            elif isinstance(value, np.ndarray) and value.shape == (3,):
-                                value = value.reshape(3, 1, 1)
+                                value = np.array(flat_values, dtype=np.float64).reshape(-1, 1, 1)
+                            elif isinstance(value, np.ndarray) and value.ndim == 1:
+                                value = value.reshape(-1, 1, 1)
 
                     episode_stats[feature_name][stat_name] = value
 
@@ -1153,15 +1164,15 @@ def _save_episode_images_for_video(
     # Get all items for this episode
     episode_dataset = imgs_dataset.select(range(from_idx, to_idx))
 
+    is_depth = img_key in dataset.meta.depth_keys
+    frame_pattern = DEPTH_FILE_PATTERN if is_depth else IMAGE_FILE_PATTERN
+
     # Define function to save a single image
     def save_single_image(i_item_tuple):
         i, item = i_item_tuple
-        img = item[img_key]
-        # Use frame-XXXXXX.png format to match encode_video_frames expectations
-        img.save(str(imgs_dir / f"frame-{i:06d}.png"), quality=100)
+        write_image(item[img_key], imgs_dir / frame_pattern.format(frame_index=i))
         return i
 
-    # Save images with proper naming convention for encode_video_frames (frame-XXXXXX.png)
     items = list(enumerate(episode_dataset))
 
     with ThreadPoolExecutor(max_workers=num_workers) as executor:
@@ -1193,13 +1204,14 @@ def _save_batch_episodes_images(
     hf_dataset = dataset.hf_dataset.with_format(None)
     imgs_dataset = hf_dataset.select_columns(img_key)
 
+    is_depth = img_key in dataset.meta.depth_keys
+    frame_pattern = DEPTH_FILE_PATTERN if is_depth else IMAGE_FILE_PATTERN
+
     # Define function to save a single image with global frame index
     # Defined once outside the loop to avoid repeated closure creation
     def save_single_image(i_item_tuple, base_frame_idx, img_key_param):
         i, item = i_item_tuple
-        img = item[img_key_param]
-        # Use global frame index for naming
-        img.save(str(imgs_dir / f"frame-{base_frame_idx + i:06d}.png"), quality=100)
+        write_image(item[img_key_param], imgs_dir / frame_pattern.format(frame_index=base_frame_idx + i))
         return i
 
     episode_durations = []
@@ -1290,7 +1302,7 @@ def _estimate_frame_size_via_calibration(
     episode_indices: list[int],
     temp_dir: Path,
     fps: int,
-    camera_encoder: VideoEncoderConfig,
+    video_encoder: VideoEncoderConfig,
     num_calibration_frames: int = 30,
 ) -> float:
     """Estimate MB per frame by encoding a small calibration sample.
@@ -1304,7 +1316,7 @@ def _estimate_frame_size_via_calibration(
         episode_indices: List of episode indices being processed.
         temp_dir: Temporary directory for calibration files.
         fps: Frames per second for video encoding.
-        camera_encoder: Video encoder settings used for calibration encoding.
+        video_encoder: Video encoder settings used for calibration encoding.
         num_calibration_frames: Number of frames to use for calibration (default: 30).
 
     Returns:
@@ -1329,10 +1341,11 @@ def _estimate_frame_size_via_calibration(
         hf_dataset = dataset.hf_dataset.with_format(None)
         sample_indices = range(from_idx, from_idx + num_frames)
 
-        # Save calibration frames
+        # Save calibration frames using the suffix/format the encoder expects.
+        is_depth = img_key in dataset.meta.depth_keys
+        frame_pattern = DEPTH_FILE_PATTERN if is_depth else IMAGE_FILE_PATTERN
         for i, idx in enumerate(sample_indices):
-            img = hf_dataset[idx][img_key]
-            img.save(str(calibration_dir / f"frame-{i:06d}.png"), quality=100)
+            write_image(hf_dataset[idx][img_key], calibration_dir / frame_pattern.format(frame_index=i))
 
         # Encode calibration video
         calibration_video_path = calibration_dir / "calibration.mp4"
@@ -1340,7 +1353,7 @@ def _estimate_frame_size_via_calibration(
             imgs_dir=calibration_dir,
             video_path=calibration_video_path,
             fps=fps,
-            camera_encoder=camera_encoder,
+            video_encoder=video_encoder,
             overwrite=True,
         )
 
@@ -1613,6 +1626,7 @@ def recompute_stats(
         raise ValueError(f"No parquet files found in {data_dir}")
 
     all_episode_stats = []
+    # TODO: enable image and video stats re-computation
     numeric_keys = [k for k, v in features_to_compute.items() if v["dtype"] not in ["image", "video"]]
 
     for parquet_path in tqdm(parquet_files, desc="Computing stats from data files"):
@@ -1658,7 +1672,8 @@ def convert_image_to_video_dataset(
     dataset: LeRobotDataset,
     output_dir: Path | None = None,
     repo_id: str | None = None,
-    camera_encoder: VideoEncoderConfig | None = None,
+    rgb_encoder: RGBEncoderConfig | None = None,
+    depth_encoder: DepthEncoderConfig | None = None,
     episode_indices: list[int] | None = None,
     num_workers: int = 4,
     max_episodes_per_batch: int | None = None,
@@ -1670,21 +1685,32 @@ def convert_image_to_video_dataset(
     LeRobot dataset structure with videos stored in chunked MP4 files.
 
     Args:
-        dataset: The source LeRobot dataset with images
-        output_dir: Root directory where the edited dataset will be stored. If not specified, defaults to $HF_LEROBOT_HOME/repo_id. Equivalent to new_root in EditDatasetConfig.
-        repo_id: Edited dataset identifier. Equivalent to new_repo_id in EditDatasetConfig.
-        camera_encoder: Video encoder settings
-            (``None`` uses :func:`~lerobot.configs.camera_encoder_defaults`).
-        episode_indices: List of episode indices to convert (None = all episodes)
-        num_workers: Number of threads for parallel processing (default: 4)
-        max_episodes_per_batch: Maximum episodes per video batch to avoid memory issues (None = no limit)
-        max_frames_per_batch: Maximum frames per video batch to avoid memory issues (None = no limit)
+        dataset: The source LeRobot dataset with images.
+        output_dir: Root directory where the converted dataset will be stored. When
+            ``None``, defaults to ``$HF_LEROBOT_HOME/repo_id``. Equivalent to
+            ``new_root`` in ``EditDatasetConfig``.
+        repo_id: Converted dataset identifier. Equivalent to ``new_repo_id`` in
+            ``EditDatasetConfig``.
+        rgb_encoder: Video encoder settings applied to RGB cameras. When ``None``,
+            :func:`~lerobot.configs.video.rgb_encoder_defaults` is used.
+        depth_encoder: Video encoder settings applied to depth-map cameras, including
+            the quantization parameters persisted to the dataset metadata. When
+            ``None``, :func:`~lerobot.configs.video.depth_encoder_defaults` is used.
+        episode_indices: Episode indices to convert. When ``None``, all episodes are
+            converted.
+        num_workers: Number of threads for parallel processing.
+        max_episodes_per_batch: Maximum episodes per video batch, to bound memory use.
+            ``None`` means no limit.
+        max_frames_per_batch: Maximum frames per video batch, to bound memory use.
+            ``None`` means no limit.
 
     Returns:
-        New LeRobotDataset with images encoded as videos
+        A new :class:`LeRobotDataset` with images encoded as videos.
     """
-    if camera_encoder is None:
-        camera_encoder = camera_encoder_defaults()
+    if rgb_encoder is None:
+        rgb_encoder = rgb_encoder_defaults()
+    if depth_encoder is None:
+        depth_encoder = depth_encoder_defaults()
 
     # Check that it's an image dataset
     if len(dataset.meta.video_keys) > 0:
@@ -1709,10 +1735,7 @@ def convert_image_to_video_dataset(
     logging.info(
         f"Converting {len(episode_indices)} episodes with {len(img_keys)} cameras from {dataset.repo_id}"
     )
-    logging.info(
-        f"Video codec: {camera_encoder.vcodec}, pixel format: {camera_encoder.pix_fmt}, "
-        f"GOP: {camera_encoder.g}, CRF: {camera_encoder.crf}"
-    )
+    logging.info(f"RGB video encoder: {rgb_encoder}, depth video encoder: {depth_encoder}")
 
     # Create new features dict, converting image features to video features
     new_features = {}
@@ -1774,6 +1797,8 @@ def convert_image_to_video_dataset(
         episode_lengths = {ep_idx: dataset.meta.episodes["length"][ep_idx] for ep_idx in episode_indices}
 
         for img_key in tqdm(img_keys, desc="Processing cameras"):
+            target_encoder = depth_encoder if img_key in dataset.meta.depth_keys else rgb_encoder
+
             # Estimate size per frame by encoding a small calibration sample
             # This provides accurate compression ratio for the specific codec parameters
             size_per_frame_mb = _estimate_frame_size_via_calibration(
@@ -1782,7 +1807,7 @@ def convert_image_to_video_dataset(
                 episode_indices=episode_indices,
                 temp_dir=temp_dir,
                 fps=fps,
-                camera_encoder=camera_encoder,
+                video_encoder=target_encoder,
             )
 
             logging.info(f"Processing camera: {img_key}")
@@ -1824,7 +1849,7 @@ def convert_image_to_video_dataset(
                     imgs_dir=imgs_dir,
                     video_path=video_path,
                     fps=fps,
-                    camera_encoder=camera_encoder,
+                    video_encoder=target_encoder,
                     overwrite=True,
                 )
 
@@ -1863,16 +1888,11 @@ def convert_image_to_video_dataset(
         new_meta.info.total_tasks = dataset.meta.total_tasks
         new_meta.info.splits = {"train": f"0:{len(episode_indices)}"}
 
-        # Update video info for all image keys (now videos)
-        # We need to manually set video info since update_video_info() checks video_keys first
+        # Update video info for all image keys (now videos). They are registered as
+        # video features above, so update_video_info populates their (still-empty) info.
         for img_key in img_keys:
-            if not new_meta.features[img_key].get("info", None):
-                video_path = new_meta.root / new_meta.video_path.format(
-                    video_key=img_key, chunk_index=0, file_index=0
-                )
-                new_meta.info.features[img_key]["info"] = get_video_info(
-                    video_path, camera_encoder=camera_encoder
-                )
+            target_encoder = depth_encoder if img_key in dataset.meta.depth_keys else rgb_encoder
+            new_meta.update_video_info(video_key=img_key, video_encoder=target_encoder)
 
         write_info(new_meta.info, new_meta.root)
 
@@ -1899,11 +1919,11 @@ def convert_image_to_video_dataset(
 
 def _reencode_video_worker(args: tuple) -> Path:
     """Picklable worker for :func:`reencode_dataset`'s process pool."""
-    video_path, camera_encoder, encoder_threads = args
+    video_path, video_encoder, encoder_threads = args
     reencode_video(
         input_video_path=video_path,
         output_video_path=video_path,
-        camera_encoder=camera_encoder,
+        video_encoder=video_encoder,
         encoder_threads=encoder_threads,
         overwrite=True,
     )
@@ -1912,7 +1932,8 @@ def _reencode_video_worker(args: tuple) -> Path:
 
 def reencode_dataset(
     dataset: LeRobotDataset,
-    camera_encoder: VideoEncoderConfig,
+    rgb_encoder: RGBEncoderConfig | None = None,
+    depth_encoder: DepthEncoderConfig | None = None,
     encoder_threads: int | None = None,
     num_workers: int | None = None,
 ) -> LeRobotDataset:
@@ -1923,8 +1944,11 @@ def reencode_dataset(
     Args:
         dataset: An existing :class:`LeRobotDataset` whose videos will be
             re-encoded.
-        camera_encoder: Target encoder configuration applied to every video
-            file.
+        rgb_encoder: Target encoder configuration applied to every RGB video
+            file. If ``None``, re-encoding is skipped for RGB videos.
+        depth_encoder: Target encoder configuration applied to every depth video
+            file. If ``None``, re-encoding is skipped for depth videos.
+            Quantization parameters will not override the ones in the current dataset.
         encoder_threads: Per-encoder thread count forwarded to
             :func:`reencode_video`. ``None`` lets the codec decide.
         num_workers: Number of parallel processes. ``None`` or ``0`` means
@@ -1936,23 +1960,35 @@ def reencode_dataset(
         on disk.
     """
     meta = dataset.meta
-    video_paths_list = []
+    video_keys_encoders_dict = {}
+    video_keys_paths_dict = {}
+
+    if rgb_encoder is None and depth_encoder is None:
+        raise ValueError("Either rgb_encoder or depth_encoder must be provided")
 
     # Only re-encode if the videos are not already encoded with the given video encoding parameters
     for video_key in meta.video_keys:
         current_info = meta.info.features[video_key].get("info", {})
-        current_encoder = VideoEncoderConfig.from_video_info(current_info)
-        if current_encoder != camera_encoder:
-            video_paths_list.extend((meta.root / VIDEO_DIR / video_key).rglob("*.mp4"))
+        current_encoder = encoder_config_from_video_info(current_info)
+        target_encoder = depth_encoder if video_key in meta.depth_keys else rgb_encoder
+        if target_encoder is None:
+            logging.info(f"No encoder provided for {video_key} video. Skipping re-encoding.")
+        elif current_encoder != target_encoder:
+            video_keys_paths_dict[video_key] = list((meta.root / VIDEO_DIR / video_key).rglob("*.mp4"))
+            video_keys_encoders_dict[video_key] = target_encoder
         else:
-            logging.info(f"{video_key} videos are already encoded with {camera_encoder}. Nothing to do.")
+            logging.info(f"{video_key} videos are already encoded with {target_encoder}. Nothing to do.")
 
-    if len(video_paths_list) == 0:
+    if len(video_keys_paths_dict) == 0:
         logging.warning("Dataset has no videos to re-encode.")
         return dataset
-    logging.info(f"Re-encoding {len(video_paths_list)} video file(s) with {camera_encoder}")
+    logging.info(f"Re-encoding {sum(len(paths) for paths in video_keys_paths_dict.values())} video file(s).")
 
-    worker_args = [(vp, camera_encoder, encoder_threads) for vp in video_paths_list]
+    worker_args = [
+        (path, encoder, encoder_threads)
+        for video_key, encoder in video_keys_encoders_dict.items()
+        for path in video_keys_paths_dict[video_key]
+    ]
     if num_workers and num_workers > 1:
         with ProcessPoolExecutor(max_workers=num_workers) as pool:
             futures = [pool.submit(_reencode_video_worker, args) for args in worker_args]
@@ -1966,10 +2002,15 @@ def reencode_dataset(
         for args in tqdm(worker_args, desc="Re-encoding videos"):
             _reencode_video_worker(args)
 
-    # Refresh video info in metadata for every video key.
-    for vid_key in meta.video_keys:
-        video_path = meta.root / meta.get_video_file_path(0, vid_key)
-        meta.info.features[vid_key]["info"] = get_video_info(video_path, camera_encoder=camera_encoder)
+    # Refresh video info in metadata for every re-encoded key. Re-encoding only
+    # changes codec/container params, so for depth videos we preserve ``is_depth_map``
+    # and the depth quantization params (``video.depth_min`` / ``video.depth_max`` /
+    # ...), which describe the data rather than the codec and must survive a transcode.
+    # RGB videos pass an empty set: still a refresh, but nothing to preserve.
+    depth_preserve_keys = {"is_depth_map", *(f"video.{n}" for n in DEPTH_ENCODER_INFO_FIELD_NAMES)}
+    for video_key, encoder in video_keys_encoders_dict.items():
+        preserve_keys = depth_preserve_keys if video_key in meta.depth_keys else set()
+        meta.update_video_info(video_key=video_key, video_encoder=encoder, preserve_keys=preserve_keys)
 
     write_info(meta.info, meta.root)
     logging.info("Dataset metadata updated.")

src/lerobot/datasets/dataset_writer.py

@@ -31,7 +31,13 @@ import PIL.Image
 import pyarrow.parquet as pq
 import torch
 
-from lerobot.configs import VideoEncoderConfig, camera_encoder_defaults
+from lerobot.configs import (
+    DepthEncoderConfig,
+    RGBEncoderConfig,
+    VideoEncoderConfig,
+    depth_encoder_defaults,
+    rgb_encoder_defaults,
+)
 
 from .compute_stats import compute_episode_stats
 from .dataset_metadata import LeRobotDatasetMetadata
@@ -48,6 +54,7 @@ from .io_utils import (
     write_info,
 )
 from .utils import (
+    DEFAULT_DEPTH_PATH,
     DEFAULT_EPISODES_PATH,
     DEFAULT_IMAGE_PATH,
     update_chunk_file_indices,
@@ -67,17 +74,22 @@ def _encode_video_worker(
     episode_index: int,
     root: Path,
     fps: int,
-    camera_encoder: VideoEncoderConfig | None = None,
+    video_encoder: VideoEncoderConfig | None = None,
     encoder_threads: int | None = None,
 ) -> Path:
     temp_path = Path(tempfile.mkdtemp(dir=root)) / f"{video_key}_{episode_index:03d}.mp4"
-    fpath = DEFAULT_IMAGE_PATH.format(image_key=video_key, episode_index=episode_index, frame_index=0)
+    path_template = (
+        DEFAULT_DEPTH_PATH
+        if video_encoder is not None and isinstance(video_encoder, DepthEncoderConfig)
+        else DEFAULT_IMAGE_PATH
+    )
+    fpath = path_template.format(image_key=video_key, episode_index=episode_index, frame_index=0)
     img_dir = (root / fpath).parent
     encode_video_frames(
         img_dir,
         temp_path,
         fps,
-        camera_encoder=camera_encoder,
+        video_encoder=video_encoder,
         encoder_threads=encoder_threads,
         overwrite=True,
     )
@@ -96,7 +108,8 @@ class DatasetWriter:
         self,
         meta: LeRobotDatasetMetadata,
         root: Path,
-        camera_encoder: VideoEncoderConfig | None,
+        rgb_encoder: RGBEncoderConfig | None,
+        depth_encoder: DepthEncoderConfig | None,
         encoder_threads: int | None,
         batch_encoding_size: int,
         streaming_encoder: StreamingVideoEncoder | None = None,
@@ -108,8 +121,11 @@ class DatasetWriter:
             meta: Dataset metadata instance (used for feature schema, chunk
                 settings, and episode persistence).
             root: Local dataset root directory.
-            camera_encoder: Video encoder settings applied to all cameras.
-                ``None`` uses :func:`~lerobot.configs.camera_encoder_defaults`.
+            rgb_encoder: Video encoder settings applied to RGB cameras. When
+                ``None``, :func:`~lerobot.configs.video.rgb_encoder_defaults` is used.
+            depth_encoder: Video encoder settings applied to depth cameras, including
+                the quantization parameters. When ``None``,
+                :func:`~lerobot.configs.video.depth_encoder_defaults` is used.
             encoder_threads: Number of encoder threads (global). ``None``
                 lets the codec decide.
             batch_encoding_size: Number of episodes to accumulate before
@@ -120,7 +136,8 @@ class DatasetWriter:
         """
         self._meta = meta
         self._root = root
-        self._camera_encoder = camera_encoder or camera_encoder_defaults()
+        self._rgb_encoder = rgb_encoder or rgb_encoder_defaults()
+        self._depth_encoder = depth_encoder or depth_encoder_defaults()
         self._encoder_threads = encoder_threads
         self._batch_encoding_size = batch_encoding_size
         self._streaming_encoder = streaming_encoder
@@ -145,7 +162,8 @@ class DatasetWriter:
         return ep_buffer
 
     def _get_image_file_path(self, episode_index: int, image_key: str, frame_index: int) -> Path:
-        fpath = DEFAULT_IMAGE_PATH.format(
+        path_template = DEFAULT_DEPTH_PATH if image_key in self._meta.depth_keys else DEFAULT_IMAGE_PATH
+        fpath = path_template.format(
             image_key=image_key, episode_index=episode_index, frame_index=frame_index
         )
         return self._root / fpath
@@ -195,6 +213,7 @@ class DatasetWriter:
         if frame_index == 0 and self._streaming_encoder is not None:
             self._streaming_encoder.start_episode(
                 video_keys=list(self._meta.video_keys),
+                depth_video_keys=list(self._meta.depth_keys),
                 temp_dir=self._root,
             )
 
@@ -282,10 +301,13 @@ class DatasetWriter:
         if use_streaming:
             streaming_results = self._streaming_encoder.finish_episode()
             for video_key in self._meta.video_keys:
+                normalization_factor = 255.0 if video_key not in self._meta.depth_keys else 1.0
                 temp_path, video_stats = streaming_results[video_key]
                 if video_stats is not None:
                     ep_stats[video_key] = {
-                        k: v if k == "count" else np.squeeze(v.reshape(1, -1, 1, 1) / 255.0, axis=0)
+                        k: v
+                        if k == "count"
+                        else np.squeeze(v.reshape(1, -1, 1, 1) / normalization_factor, axis=0)
                         for k, v in video_stats.items()
                     }
                 ep_metadata.update(self._save_episode_video(video_key, episode_index, temp_path=temp_path))
@@ -300,7 +322,7 @@ class DatasetWriter:
                             episode_index,
                             self._root,
                             self._meta.fps,
-                            self._camera_encoder,
+                            self._depth_encoder if video_key in self._meta.depth_keys else self._rgb_encoder,
                             self._encoder_threads,
                         ): video_key
                         for video_key in self._meta.video_keys
@@ -511,7 +533,12 @@ class DatasetWriter:
 
         # Update video info (only needed when first episode is encoded)
         if episode_index == 0:
-            self._meta.update_video_info(video_key, camera_encoder=self._camera_encoder)
+            self._meta.update_video_info(
+                video_key,
+                video_encoder=self._depth_encoder
+                if video_key in self._meta.depth_keys
+                else self._rgb_encoder,
+            )
             write_info(self._meta.info, self._meta.root)
 
         metadata = {
@@ -578,13 +605,14 @@ class DatasetWriter:
             self.image_writer.wait_until_done()
 
     def _encode_temporary_episode_video(self, video_key: str, episode_index: int) -> Path:
-        """Use ffmpeg to convert frames stored as png into mp4 videos."""
+        """Use ffmpeg to convert frames stored as png/tiff into mp4 videos."""
+        is_depth = video_key in self._meta.depth_keys
         return _encode_video_worker(
             video_key,
             episode_index,
             self._root,
             self._meta.fps,
-            self._camera_encoder,
+            self._depth_encoder if is_depth else self._rgb_encoder,
             self._encoder_threads,
         )
 

src/lerobot/datasets/depth_utils.py

@@ -0,0 +1,268 @@
+#!/usr/bin/env python
+
+# Copyright 2026 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+Depth encoding/decoding helpers for :class:`DepthEncoderConfig`.
+"""
+
+import math
+from typing import Literal
+
+import av
+import numpy as np
+import torch
+from numpy.typing import NDArray
+
+from lerobot.configs.video import (
+    DEFAULT_DEPTH_MAX,
+    DEFAULT_DEPTH_MIN,
+    DEFAULT_DEPTH_PIX_FMT,
+    DEFAULT_DEPTH_SHIFT,
+    DEFAULT_DEPTH_USE_LOG,
+    DEPTH_METER_UNIT,
+    DEPTH_MILLIMETER_UNIT,
+    DEPTH_QMAX,
+)
+
+from .image_writer import squeeze_single_channel
+from .pyav_utils import write_u16_plane
+
+_MM_PER_METRE = 1000.0
+_UINT16_MAX = 65535
+
+
+def _validate_log_quant_params(depth_min: float, shift: float) -> None:
+    """Ensure ``log(depth_min + shift)`` is finite."""
+    if depth_min + shift <= 0:
+        raise ValueError(
+            f"depth_min + shift must be positive for logarithmic quantization, "
+            f"got depth_min={depth_min} + shift={shift} = {depth_min + shift}"
+        )
+
+
+def _depth_input_to_float32_and_unit(
+    depth: NDArray[np.integer] | NDArray[np.floating],
+    input_unit: Literal["auto", DEPTH_METER_UNIT, DEPTH_MILLIMETER_UNIT],
+) -> tuple[NDArray[np.float32], Literal[DEPTH_METER_UNIT, DEPTH_MILLIMETER_UNIT]]:
+    """Convert depth to float32 in the chosen unit, and return the resolved unit."""
+    resolved_unit = (
+        (DEPTH_METER_UNIT if np.issubdtype(depth.dtype, np.floating) else DEPTH_MILLIMETER_UNIT)
+        if input_unit == "auto"
+        else input_unit
+    )
+    return depth.astype(np.float32, order="K"), resolved_unit
+
+
+def quantize_depth(
+    depth: NDArray[np.uint16] | NDArray[np.float32] | torch.Tensor,
+    depth_min: float = DEFAULT_DEPTH_MIN,
+    depth_max: float = DEFAULT_DEPTH_MAX,
+    shift: float = DEFAULT_DEPTH_SHIFT,
+    use_log: bool = DEFAULT_DEPTH_USE_LOG,
+    pix_fmt: str = DEFAULT_DEPTH_PIX_FMT,
+    video_backend: str | None = "pyav",
+    input_unit: Literal["auto", DEPTH_METER_UNIT, DEPTH_MILLIMETER_UNIT] = "auto",
+) -> NDArray[np.uint16] | av.VideoFrame:
+    """Quantize depth to 12-bit codes (``uint16``, values ``0…DEPTH_QMAX``).
+
+    Depth maps are packed into 12-bit integer frames so they fit in standard
+    high-bit-depth pixel formats (e.g. ``yuv420p12le`` / ``gray12le``)
+    and can be encoded by widely supported video codecs (e.g. HEVC Main 12).
+    Logarithmic quantization is the default because it allocates more quanta
+    to near-range depth, which matches the (1/depth) error profile of typical
+    depth sensors. Math is ported from BEHAVIOR-1K's ``obs_utils.py``.
+
+    **Input units**:
+
+    - ``input_unit="auto"`` (default): infer from dtype (floating = m, non-floating = mm).
+    - ``input_unit="mm"``: interpret input values as millimetres.
+    - ``input_unit="m"``: interpret input values as metres.
+
+    Quantization math runs in the **resolved input unit**.
+
+    ``depth_min``, ``depth_max``, and ``shift`` are always in **metres**.
+
+    Args:
+        depth: Depth map; ``torch.Tensor`` is moved to CPU for conversion.
+        depth_min: Depth (metres) at quantum ``0``.
+        depth_max: Depth (metres) at quantum :data:`DEPTH_QMAX`.
+        shift: Depth shift (metres); used in log mode. Must satisfy ``depth_min + shift > 0``.
+        use_log: If ``True`` (default), quantize in log space.
+        video_backend: Video backend to use for encoding. Defaults to "pyav".
+        input_unit: Input unit policy (``"auto"``, ``"mm"``, ``"m"``).
+
+    Returns:
+        ``numpy.ndarray``, ``dtype=uint16``, same shape as ``depth``, values in
+        ``[0, DEPTH_QMAX]``.
+
+    Raises:
+        ValueError: If ``input_unit`` is not ``"auto"``, ``"mm"``, or ``"m"``.
+        ValueError: If ``use_log=True`` and ``depth_min + shift <= 0``.
+    """
+    if input_unit not in ("auto", DEPTH_METER_UNIT, DEPTH_MILLIMETER_UNIT):
+        raise ValueError(
+            f"input_unit must be 'auto', '{DEPTH_METER_UNIT}', or '{DEPTH_MILLIMETER_UNIT}', got {input_unit!r}"
+        )
+
+    if isinstance(depth, torch.Tensor):
+        depth = depth.detach().cpu().numpy()
+
+    # Squeeze single-channel dim: (H, W, 1) or (1, H, W) → (H, W)
+    depth = squeeze_single_channel(depth)
+
+    depth_f, resolved_unit = _depth_input_to_float32_and_unit(depth, input_unit=input_unit)
+
+    # Convert depth_min, depth_max, and shift to the resolved input unit.
+    depth_min_u = (
+        np.float32(depth_min) if resolved_unit == DEPTH_METER_UNIT else np.float32(depth_min * _MM_PER_METRE)
+    )
+    depth_max_u = (
+        np.float32(depth_max) if resolved_unit == DEPTH_METER_UNIT else np.float32(depth_max * _MM_PER_METRE)
+    )
+    shift_u = np.float32(shift) if resolved_unit == DEPTH_METER_UNIT else np.float32(shift * _MM_PER_METRE)
+
+    # Normalization and quantization is performed in the resolved input unit.
+    if use_log:
+        _validate_log_quant_params(depth_min, shift)
+        log_min = math.log(float(depth_min_u + shift_u))
+        log_max = math.log(float(depth_max_u + shift_u))
+        norm = (np.log(depth_f + shift_u) - log_min) / (log_max - log_min)
+    else:
+        norm = (depth_f - depth_min_u) / (depth_max_u - depth_min_u)
+
+    quantized = np.rint(norm * DEPTH_QMAX).clip(0, DEPTH_QMAX).astype(np.uint16, copy=False)
+
+    if video_backend == "pyav":
+        frame = av.VideoFrame.from_ndarray(quantized, format=pix_fmt)
+        write_u16_plane(frame.planes[0], quantized)
+        return frame
+    else:
+        return quantized
+
+
+def dequantize_depth(
+    quantized: NDArray[np.uint16] | av.VideoFrame | torch.Tensor,
+    depth_min: float = DEFAULT_DEPTH_MIN,
+    depth_max: float = DEFAULT_DEPTH_MAX,
+    shift: float = DEFAULT_DEPTH_SHIFT,
+    use_log: bool = DEFAULT_DEPTH_USE_LOG,
+    pix_fmt: str = DEFAULT_DEPTH_PIX_FMT,
+    output_unit: Literal[DEPTH_METER_UNIT, DEPTH_MILLIMETER_UNIT] = DEPTH_MILLIMETER_UNIT,
+    output_tensor: bool = True,
+    output_channel_last: bool = False,
+) -> NDArray[np.uint16] | NDArray[np.float32] | torch.Tensor:
+    """Inverse of :func:`quantize_depth`.
+
+    Decoding inverts the same normalized code mapping as :func:`quantize_depth`
+    using ``depth_min`` / ``depth_max`` / ``shift`` (in metres), then returns
+    the requested output unit. Tuning arguments **must match** :func:`quantize_depth`.
+
+    Accepted input layouts :
+
+    - ``(H, W, 1)`` or ``(H, W)`` — single frame with channel-last.
+    - ``(..., 1, H, W)`` — batched frames with channel-first.
+    - ``(..., H, W, 1)`` — batched frames with channel-last.
+    Output layout is determined by ``output_channel_last``.
+
+    Args:
+        quantized: 12-bit codes in ``[0, DEPTH_QMAX]``. ``np.ndarray``,
+            ``av.VideoFrame``, or ``torch.Tensor`` (any integer or float dtype).
+        depth_min, depth_max, shift, use_log: Same as :func:`quantize_depth` (metres).
+        pix_fmt: Pixel format used to extract the plane from an ``av.VideoFrame``.
+        output_unit: ``"mm"`` returns ``uint16`` millimetres (rint, clip
+            ``[0, 65535]``) when returning a numpy array, or ``float32`` mm when
+            ``output_tensor=True``. ``"m"`` returns ``float32`` metres in
+            ``[depth_min, depth_max]``.
+        output_tensor: If True, return a ``torch.Tensor`` instead of a numpy array.
+
+    Returns:
+        Depth map in the requested unit and dtype.
+
+    Raises:
+        ValueError: If ``output_unit`` is not ``"m"`` or ``"mm"``.
+        ValueError: If ``use_log=True`` and ``depth_min + shift <= 0``.
+    """
+    if output_unit not in (DEPTH_METER_UNIT, DEPTH_MILLIMETER_UNIT):
+        raise ValueError(
+            f"output_unit must be '{DEPTH_METER_UNIT}' or '{DEPTH_MILLIMETER_UNIT}', got {output_unit!r}"
+        )
+    if use_log:
+        _validate_log_quant_params(depth_min, shift)
+
+    if isinstance(quantized, av.VideoFrame):
+        quantized = quantized.to_ndarray(format=pix_fmt)
+
+    # Compute the scale and offset first.
+    depth_min_m = float(depth_min)
+    depth_max_m = float(depth_max)
+    shift_m = float(shift)
+    if use_log:
+        log_min = math.log(depth_min_m + shift_m)
+        log_max = math.log(depth_max_m + shift_m)
+        scale = (log_max - log_min) / DEPTH_QMAX
+        offset = log_min
+    else:
+        scale = (depth_max_m - depth_min_m) / DEPTH_QMAX
+        offset = depth_min_m
+
+    # ── Torch path: stay on the input device, single fp32 allocation. ────────
+    if isinstance(quantized, torch.Tensor):
+        if quantized.ndim >= 3:
+            # Drop the single-channel dimension so the math runs on (..., H, W).
+            quantized = quantized.squeeze(-3) if quantized.shape[-3] == 1 else quantized.squeeze(-1)
+
+        # Single allocation we own; everything else is in-place.
+        buf = quantized.to(dtype=torch.float32, copy=True)
+        buf.mul_(scale).add_(offset)
+        if use_log:
+            buf.exp_().sub_(shift_m)
+        buf.clamp_(depth_min_m, depth_max_m)
+        buf.unsqueeze_(-1) if output_channel_last else buf.unsqueeze_(-3)
+
+        if output_unit == DEPTH_METER_UNIT:
+            return buf if output_tensor else buf.cpu().numpy()
+
+        # mm path: round + clamp in float32, skipping the uint16 round-trip
+        # when returning a tensor (torch.uint16 is poorly supported).
+        buf.mul_(_MM_PER_METRE).round_().clamp_(0.0, _UINT16_MAX)
+        if output_tensor:
+            return buf
+        return buf.cpu().numpy().astype(np.uint16, copy=False)
+
+    # ── NumPy path: single fp32 allocation, ``out=`` for in-place math. ─────
+    arr = np.asarray(quantized)
+    if arr.ndim >= 3:
+        # Drop the single-channel dimension so the math runs on (..., H, W).
+        arr = np.squeeze(arr, axis=-3) if arr.shape[-3] == 1 else np.squeeze(arr, axis=-1)
+
+    buf = np.empty(arr.shape, dtype=np.float32)
+    np.multiply(arr, scale, out=buf)
+    np.add(buf, offset, out=buf)
+    if use_log:
+        np.exp(buf, out=buf)
+        np.subtract(buf, shift_m, out=buf)
+    np.clip(buf, depth_min_m, depth_max_m, out=buf)
+    buf = np.expand_dims(buf, axis=-1) if output_channel_last else np.expand_dims(buf, axis=-3)
+
+    if output_unit == DEPTH_METER_UNIT:
+        return torch.from_numpy(buf) if output_tensor else buf
+
+    np.multiply(buf, _MM_PER_METRE, out=buf)
+    np.rint(buf, out=buf)
+    np.clip(buf, 0.0, _UINT16_MAX, out=buf)
+    if output_tensor:
+        # torch.uint16 support is very limited; return float32 millimetres.
+        return torch.from_numpy(buf)
+    return buf.astype(np.uint16, copy=False)

src/lerobot/datasets/factory.py

@@ -14,6 +14,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
+import math
 from pprint import pformat
 
 import torch
@@ -96,6 +97,7 @@ def make_dataset(cfg: TrainPipelineConfig) -> LeRobotDataset | MultiLeRobotDatas
                 revision=cfg.dataset.revision,
                 video_backend=cfg.dataset.video_backend,
                 return_uint8=True,
+                depth_output_unit=cfg.dataset.depth_output_unit,
                 tolerance_s=cfg.tolerance_s,
             )
         else:
@@ -126,7 +128,87 @@ def make_dataset(cfg: TrainPipelineConfig) -> LeRobotDataset | MultiLeRobotDatas
 
     if cfg.dataset.use_imagenet_stats:
         for key in dataset.meta.camera_keys:
+            if key in dataset.meta.depth_keys:
+                continue  # Exclude depth keys from ImageNet stats
             for stats_type, stats in IMAGENET_STATS.items():
                 dataset.meta.stats[key][stats_type] = torch.tensor(stats, dtype=torch.float32)
 
     return dataset
+
+
+def make_train_eval_datasets(
+    cfg: TrainPipelineConfig,
+) -> tuple[LeRobotDataset | MultiLeRobotDataset, LeRobotDataset | None]:
+    """Create train and optional eval datasets by splitting episodes based on eval_split.
+
+    The last ceil(n_episodes * eval_split) episodes per task are held out for evaluation.
+    If eval_split == 0.0, returns (full_dataset, None).
+    """
+    full_dataset = make_dataset(cfg)
+
+    if cfg.dataset.eval_split == 0.0:
+        return full_dataset, None
+
+    base_episodes = (
+        full_dataset.episodes if full_dataset.episodes is not None else list(range(full_dataset.num_episodes))
+    )
+
+    episode_tasks = full_dataset.meta.episodes["tasks"]
+    task_to_episodes: dict[str, list[int]] = {}
+    for ep_idx in base_episodes:
+        task_key = episode_tasks[ep_idx][0] if episode_tasks[ep_idx] else ""
+        task_to_episodes.setdefault(task_key, []).append(ep_idx)
+
+    train_episodes, eval_episodes = [], []
+    for eps in task_to_episodes.values():
+        n_eval = math.ceil(len(eps) * cfg.dataset.eval_split)
+        train_episodes.extend(eps[: len(eps) - n_eval])
+        eval_episodes.extend(eps[len(eps) - n_eval :])
+
+    if not train_episodes:
+        raise ValueError(
+            f"eval_split={cfg.dataset.eval_split} leaves 0 training episodes from {len(base_episodes)} total."
+        )
+
+    logging.info(
+        f"Train/eval split: {len(train_episodes)} train, {len(eval_episodes)} eval "
+        f"(eval_split={cfg.dataset.eval_split}, {len(task_to_episodes)} tasks)"
+    )
+
+    delta_timestamps = resolve_delta_timestamps(cfg.trainable_config, full_dataset.meta)
+
+    train_image_transforms = (
+        ImageTransforms(cfg.dataset.image_transforms) if cfg.dataset.image_transforms.enable else None
+    )
+
+    train_dataset = LeRobotDataset(
+        cfg.dataset.repo_id,
+        root=cfg.dataset.root,
+        episodes=train_episodes,
+        delta_timestamps=delta_timestamps,
+        image_transforms=train_image_transforms,
+        revision=cfg.dataset.revision,
+        video_backend=cfg.dataset.video_backend,
+        return_uint8=True,
+        tolerance_s=cfg.tolerance_s,
+    )
+
+    eval_dataset = LeRobotDataset(
+        cfg.dataset.repo_id,
+        root=cfg.dataset.root,
+        episodes=eval_episodes,
+        delta_timestamps=delta_timestamps,
+        image_transforms=None,
+        revision=cfg.dataset.revision,
+        video_backend=cfg.dataset.video_backend,
+        return_uint8=True,
+        tolerance_s=cfg.tolerance_s,
+    )
+
+    if cfg.dataset.use_imagenet_stats:
+        for ds in (train_dataset, eval_dataset):
+            for key in ds.meta.camera_keys:
+                for stats_type, stats in IMAGENET_STATS.items():
+                    ds.meta.stats[key][stats_type] = torch.tensor(stats, dtype=torch.float32)
+
+    return train_dataset, eval_dataset

src/lerobot/datasets/feature_utils.py

@@ -336,7 +336,7 @@ def validate_feature_image_or_video(
 
     Args:
         name (str): The name of the feature.
-        expected_shape (list[str]): The expected shape (C, H, W).
+        expected_shape (list[str]): The expected shape, e.g. (C, H, W) or (H, W, C).
         value: The image data to validate.
 
     Returns:

src/lerobot/datasets/image_writer.py

@@ -41,11 +41,51 @@ def safe_stop_image_writer(func):
     return wrapper
 
 
-def image_array_to_pil_image(image_array: np.ndarray, range_check: bool = True) -> PIL.Image.Image:
-    # TODO(aliberts): handle 1 channel and 4 for depth images
-    if image_array.ndim != 3:
-        raise ValueError(f"The array has {image_array.ndim} dimensions, but 3 is expected for an image.")
+def squeeze_single_channel(array: np.ndarray) -> np.ndarray:
+    """Drop a leading or trailing singleton channel dim: ``(1, H, W)`` / ``(H, W, 1)`` -> ``(H, W)``.
 
+    Unlike ``array.squeeze()``, this only removes the channel axis, never an ``H`` or ``W`` of size 1.
+    """
+    if array.ndim == 3:
+        if array.shape[0] == 1:
+            return array[0]
+        if array.shape[-1] == 1:
+            return array[..., 0]
+    return array
+
+
+def image_array_to_pil_image(image_array: np.ndarray, range_check: bool = True) -> PIL.Image.Image:
+    """Convert a NumPy array to a PIL Image, preserving precision for grayscale.
+
+    Behaviour by shape:
+
+    - ``(H, W)`` or ``(1, H, W)`` / ``(H, W, 1)``: single-channel grayscale.
+      The native dtype is preserved using the matching PIL mode
+      (``I;16`` / ``F``). This is the path used for raw depth maps (no rescaling, clamping, or downcasting)
+    - ``(3, H, W)`` / ``(H, W, 3)``: RGB. Channels-first inputs are transposed
+      to channels-last. Float inputs in ``[0, 1]`` are scaled to ``uint8``
+      (existing behaviour, gated by ``range_check``).
+
+    Other shapes / channel counts raise ``NotImplementedError`` or
+    ``ValueError``.
+    """
+    # TODO(CarolinePascal): 4 dimensions RGB-D images
+    if image_array.ndim not in (2, 3):
+        raise ValueError(f"The array has {image_array.ndim} dimensions, but 2 or 3 is expected for an image.")
+
+    # Squeeze 3D single-channel inputs to 2D so depth maps work whether the
+    # caller emits (H, W), (1, H, W), or (H, W, 1).
+    image_array = squeeze_single_channel(image_array)
+
+    if image_array.ndim == 2:
+        if image_array.dtype not in [np.uint16, np.float32]:
+            raise ValueError(
+                f"Unsupported single-channel image dtype: {image_array.dtype}. "
+                f"Supported dtypes: {sorted(str(d) for d in [np.uint16, np.float32])}."
+            )
+        return PIL.Image.fromarray(np.ascontiguousarray(image_array))
+
+    # 3D path: must be RGB (3 channels), channels-first or channels-last.
     if image_array.shape[0] == 3:
         # Transpose from pytorch convention (C, H, W) to (H, W, C)
         image_array = image_array.transpose(1, 2, 0)
@@ -71,13 +111,29 @@ def image_array_to_pil_image(image_array: np.ndarray, range_check: bool = True)
     return PIL.Image.fromarray(image_array)
 
 
+def save_kwargs_for_path(fpath: Path, compress_level: int) -> dict:
+    """Pick the right format-specific kwargs for :meth:`PIL.Image.Image.save`.
+
+    PNG uses ``compress_level`` (0-9, zlib). TIFF uses ``compression`` (raw) for lossless raw depth maps.
+    """
+    suffix = Path(fpath).suffix.lower()
+    if suffix == ".png":
+        return {"compress_level": compress_level}
+    if suffix in (".tif", ".tiff"):
+        return {"compression": "raw"}
+    else:
+        raise ValueError(f"Unsupported image file extension: {suffix}")
+
+
 def write_image(image: np.ndarray | PIL.Image.Image, fpath: Path, compress_level: int = 1):
     """
     Saves a NumPy array or PIL Image to a file.
 
     This function handles both NumPy arrays and PIL Image objects, converting
     the former to a PIL Image before saving. It includes error handling for
-    the save operation.
+    the save operation. The output format is inferred from the *fpath*
+    extension: ``.png`` → PNG with ``compress_level``, ``.tiff`` / ``.tif``
+    → lossless raw depth maps (TIFF).
 
     Args:
         image (np.ndarray | PIL.Image.Image): The image data to save.
@@ -101,7 +157,7 @@ def write_image(image: np.ndarray | PIL.Image.Image, fpath: Path, compress_level
             img = image
         else:
             raise TypeError(f"Unsupported image type: {type(image)}")
-        img.save(fpath, compress_level=compress_level)
+        img.save(fpath, **save_kwargs_for_path(fpath, compress_level))
     except Exception as e:
         logger.error("Error writing image %s: %s", fpath, e)
 

src/lerobot/datasets/io_utils.py

@@ -226,28 +226,50 @@ def load_image_as_numpy(
     Args:
         fpath (str | Path): Path to the image file.
         dtype (np.dtype): The desired data type of the output array. If floating,
-            pixels are scaled to [0, 1].
+            pixels are scaled to [0, 1]. Only used for RGB images.
         channel_first (bool): If True, converts the image to (C, H, W) format.
             Otherwise, it remains in (H, W, C) format.
 
     Returns:
         np.ndarray: The image as a numpy array.
     """
-    img = PILImage.open(fpath).convert("RGB")
-    img_array = np.array(img, dtype=dtype)
+    is_depth = fpath.endswith(".tiff") or fpath.endswith(".tif")
+    if is_depth:
+        # Preserve the native depth dtype (uint16 -> "I;16", float32 -> "F").
+        img = PILImage.open(fpath)
+        img_array = np.array(img)
+    else:
+        img = PILImage.open(fpath).convert("RGB")
+        img_array = np.array(img, dtype=dtype)
+        if np.issubdtype(dtype, np.floating):
+            img_array /= 255.0
     if channel_first:  # (H, W, C) -> (C, H, W)
-        img_array = np.transpose(img_array, (2, 0, 1))
-    if np.issubdtype(dtype, np.floating):
-        img_array /= 255.0
+        img_array = img_array[np.newaxis, ...] if img_array.ndim == 2 else np.transpose(img_array, (2, 0, 1))
     return img_array
 
 
+# PIL modes for 16-bit unsigned depth maps.
+UINT16_PIL_MODES = {"I;16", "I;16B", "I;16L"}
+
+
+def pil_to_chw_tensor(img: PILImage.Image) -> torch.Tensor:
+    """Convert a PIL image to a channel-first tensor.
+
+    ``uint16`` depth maps become ``float32 (1, H, W)`` in native units (``ToTensor``
+    would overflow them to ``int16``); all other modes use the standard ``ToTensor`` path.
+    """
+    if img.mode in UINT16_PIL_MODES:
+        return torch.from_numpy(np.array(img, dtype=np.float32))[None, ...]
+    return transforms.ToTensor()(img)
+
+
 def hf_transform_to_torch(items_dict: dict[str, list[Any]]) -> dict[str, list[torch.Tensor | str]]:
     """Convert a batch from a Hugging Face dataset to torch tensors.
 
     This transform function converts items from Hugging Face dataset format (pyarrow)
-    to torch tensors. Importantly, images are converted from PIL objects (H, W, C, uint8)
-    to a torch image representation (C, H, W, float32) in the range [0, 1]. Other
+    to torch tensors. RGB images are converted from PIL objects (H, W, C, uint8)
+    to a torch image representation (C, H, W, float32) in the range [0, 1]. Depth
+    maps are returned as float32 (1, H, W) in their native units. Other
     types are converted to torch.tensor.
 
     Args:
@@ -262,8 +284,7 @@ def hf_transform_to_torch(items_dict: dict[str, list[Any]]) -> dict[str, list[to
             continue
         first_item = items_dict[key][0]
         if isinstance(first_item, PILImage.Image):
-            to_tensor = transforms.ToTensor()
-            items_dict[key] = [to_tensor(img) for img in items_dict[key]]
+            items_dict[key] = [pil_to_chw_tensor(img) for img in items_dict[key]]
         elif first_item is None or isinstance(first_item, dict):
             pass
         else:
@@ -329,7 +350,11 @@ def item_to_torch(item: dict) -> dict:
     """
     skip_keys = {"task", *LANGUAGE_COLUMNS}
     for key, val in item.items():
-        if isinstance(val, (np.ndarray | list)) and key not in skip_keys:
+        if key in skip_keys:
+            continue
+        if isinstance(val, PILImage.Image):
+            item[key] = pil_to_chw_tensor(val)
+        elif isinstance(val, (np.ndarray | list)):
             # Convert numpy arrays and lists to torch tensors
             item[key] = torch.tensor(val)
     return item

src/lerobot/datasets/lerobot_dataset.py

@@ -24,7 +24,7 @@ import torch.utils
 from huggingface_hub import HfApi, snapshot_download
 from huggingface_hub.errors import RevisionNotFoundError
 
-from lerobot.configs import VideoEncoderConfig
+from lerobot.configs import DEFAULT_DEPTH_UNIT, DepthEncoderConfig, RGBEncoderConfig
 from lerobot.utils.constants import HF_LEROBOT_HUB_CACHE
 
 from .dataset_metadata import CODEBASE_VERSION, LeRobotDatasetMetadata
@@ -58,8 +58,10 @@ class LeRobotDataset(torch.utils.data.Dataset):
         download_videos: bool = True,
         video_backend: str | None = None,
         return_uint8: bool = False,
+        depth_output_unit: str = DEFAULT_DEPTH_UNIT,
         batch_encoding_size: int = 1,
-        camera_encoder: VideoEncoderConfig | None = None,
+        rgb_encoder: RGBEncoderConfig | None = None,
+        depth_encoder: DepthEncoderConfig | None = None,
         encoder_threads: int | None = None,
         streaming_encoding: bool = False,
         encoder_queue_maxsize: int = 30,
@@ -183,8 +185,11 @@ class LeRobotDataset(torch.utils.data.Dataset):
                 You can also use the 'pyav' decoder used by Torchvision, which used to be the default option, or 'video_reader' which is another decoder of Torchvision.
             batch_encoding_size (int, optional): Number of episodes to accumulate before batch encoding videos.
                 Set to 1 for immediate encoding (default), or higher for batched encoding. Defaults to 1.
-            camera_encoder (VideoEncoderConfig | None, optional): Video encoder settings for cameras
-                (codec, quality, etc.). When ``None``, :func:`~lerobot.configs.video.camera_encoder_defaults`
+            rgb_encoder (RGBEncoderConfig | None, optional): Video encoder settings for cameras
+                (codec, quality, etc.). When ``None``, :func:`~lerobot.configs.video.rgb_encoder_defaults`
+                is used by the writer.
+            depth_encoder (DepthEncoderConfig | None, optional): Video encoder settings for depth cameras
+                (codec, quality, etc.). When ``None``, :func:`~lerobot.configs.video.depth_encoder_defaults`
                 is used by the writer.
             encoder_threads (int | None, optional): Number of encoder threads (global). ``None`` lets the
                 codec decide.
@@ -206,6 +211,7 @@ class LeRobotDataset(torch.utils.data.Dataset):
         self.revision = revision if revision else CODEBASE_VERSION
         self._video_backend = video_backend if video_backend else get_safe_default_video_backend()
         self._return_uint8 = return_uint8
+        self._depth_output_unit = depth_output_unit
         self._batch_encoding_size = batch_encoding_size
         self._encoder_threads = encoder_threads
 
@@ -246,6 +252,7 @@ class LeRobotDataset(torch.utils.data.Dataset):
             delta_timestamps=delta_timestamps,
             image_transforms=image_transforms,
             return_uint8=self._return_uint8,
+            depth_output_unit=self._depth_output_unit,
         )
         self.image_transforms = image_transforms
 
@@ -271,14 +278,16 @@ class LeRobotDataset(torch.utils.data.Dataset):
             if streaming_encoding and len(self.meta.video_keys) > 0:
                 streaming_enc = self._build_streaming_encoder(
                     self.meta.fps,
-                    camera_encoder,
+                    rgb_encoder,
+                    depth_encoder,
                     encoder_queue_maxsize,
                     encoder_threads,
                 )
             self.writer = DatasetWriter(
                 meta=self.meta,
                 root=self.root,
-                camera_encoder=camera_encoder,
+                rgb_encoder=rgb_encoder,
+                depth_encoder=depth_encoder,
                 encoder_threads=encoder_threads,
                 batch_encoding_size=batch_encoding_size,
                 streaming_encoder=streaming_enc,
@@ -314,19 +323,22 @@ class LeRobotDataset(torch.utils.data.Dataset):
                 delta_timestamps=self.delta_timestamps,
                 image_transforms=self.image_transforms,
                 return_uint8=self._return_uint8,
+                depth_output_unit=self._depth_output_unit,
             )
         return self.reader
 
     @staticmethod
     def _build_streaming_encoder(
         fps: int,
-        camera_encoder: VideoEncoderConfig | None,
+        rgb_encoder: RGBEncoderConfig | None,
+        depth_encoder: DepthEncoderConfig | None,
         encoder_queue_maxsize: int,
         encoder_threads: int | None,
     ) -> StreamingVideoEncoder:
         return StreamingVideoEncoder(
             fps=fps,
-            camera_encoder=camera_encoder,
+            rgb_encoder=rgb_encoder,
+            depth_encoder=depth_encoder,
             queue_maxsize=encoder_queue_maxsize,
             encoder_threads=encoder_threads,
         )
@@ -369,6 +381,18 @@ class LeRobotDataset(torch.utils.data.Dataset):
             self.reader.load_and_activate()
         return self.reader.hf_dataset
 
+    @property
+    def absolute_to_relative_idx(self) -> dict[int, int] | None:
+        """Mapping from absolute frame indices to HF dataset row positions.
+
+        Non-None only for episode-filtered datasets where absolute indices
+        (from metadata) differ from row positions in the loaded HF dataset.
+        """
+        reader = self._ensure_reader()
+        if reader.hf_dataset is None:
+            reader.load_and_activate()
+        return reader._absolute_to_relative_idx
+
     # ── Writer-delegated methods ──────────────────────────────────────
 
     def add_frame(self, frame: dict) -> None:
@@ -643,7 +667,8 @@ class LeRobotDataset(torch.utils.data.Dataset):
         image_writer_threads: int = 0,
         video_backend: str | None = None,
         batch_encoding_size: int = 1,
-        camera_encoder: VideoEncoderConfig | None = None,
+        rgb_encoder: RGBEncoderConfig | None = None,
+        depth_encoder: DepthEncoderConfig | None = None,
         metadata_buffer_size: int = 10,
         streaming_encoding: bool = False,
         encoder_queue_maxsize: int = 30,
@@ -674,8 +699,10 @@ class LeRobotDataset(torch.utils.data.Dataset):
             video_backend: Video decoding backend (used when reading back).
             batch_encoding_size: Number of episodes to accumulate before
                 batch-encoding videos. ``1`` means encode immediately.
-            camera_encoder: Video encoder settings for cameras (codec, quality, etc.).
-                When ``None``, :func:`~lerobot.configs.video.camera_encoder_defaults` is used.
+            rgb_encoder: Video encoder settings for cameras (codec, quality, etc.).
+                When ``None``, :func:`~lerobot.configs.video.rgb_encoder_defaults` is used.
+            depth_encoder: Video encoder settings for depth cameras (codec, quality, etc.).
+                When ``None``, :func:`~lerobot.configs.video.depth_encoder_defaults` is used.
             encoder_threads: Number of encoder threads (global). ``None``
                 lets the codec decide.
             metadata_buffer_size: Number of episode metadata records to buffer
@@ -710,6 +737,7 @@ class LeRobotDataset(torch.utils.data.Dataset):
         obj.episodes = None
         obj._video_backend = video_backend if video_backend is not None else get_safe_default_video_backend()
         obj._return_uint8 = False
+        obj._depth_output_unit = DEFAULT_DEPTH_UNIT
         obj._batch_encoding_size = batch_encoding_size
         obj._encoder_threads = encoder_threads
 
@@ -719,12 +747,13 @@ class LeRobotDataset(torch.utils.data.Dataset):
         streaming_enc = None
         if streaming_encoding and len(obj.meta.video_keys) > 0:
             streaming_enc = cls._build_streaming_encoder(
-                fps, camera_encoder, encoder_queue_maxsize, encoder_threads
+                fps, rgb_encoder, depth_encoder, encoder_queue_maxsize, encoder_threads
             )
         obj.writer = DatasetWriter(
             meta=obj.meta,
             root=obj.root,
-            camera_encoder=camera_encoder,
+            rgb_encoder=rgb_encoder,
+            depth_encoder=depth_encoder,
             encoder_threads=encoder_threads,
             batch_encoding_size=batch_encoding_size,
             streaming_encoder=streaming_enc,
@@ -747,7 +776,8 @@ class LeRobotDataset(torch.utils.data.Dataset):
         force_cache_sync: bool = False,
         video_backend: str | None = None,
         batch_encoding_size: int = 1,
-        camera_encoder: VideoEncoderConfig | None = None,
+        rgb_encoder: RGBEncoderConfig | None = None,
+        depth_encoder: DepthEncoderConfig | None = None,
         encoder_threads: int | None = None,
         image_writer_processes: int = 0,
         image_writer_threads: int = 0,
@@ -775,8 +805,10 @@ class LeRobotDataset(torch.utils.data.Dataset):
             video_backend: Video decoding backend for reading back data.
             batch_encoding_size: Number of episodes to accumulate before
                 batch-encoding videos.
-            camera_encoder: Video encoder settings for cameras (codec, quality, etc.).
-                When ``None``, :func:`~lerobot.configs.video.camera_encoder_defaults` is used.
+            rgb_encoder: Video encoder settings for cameras (codec, quality, etc.).
+                When ``None``, :func:`~lerobot.configs.video.rgb_encoder_defaults` is used.
+            depth_encoder: Video encoder settings for depth cameras (codec, quality, etc.).
+                When ``None``, :func:`~lerobot.configs.video.depth_encoder_defaults` is used.
             encoder_threads: Number of encoder threads (global). ``None``
                 lets the codec decide.
             image_writer_processes: Subprocesses for async image writing.
@@ -804,6 +836,7 @@ class LeRobotDataset(torch.utils.data.Dataset):
         obj.episodes = None
         obj._video_backend = video_backend if video_backend else get_safe_default_video_backend()
         obj._return_uint8 = False
+        obj._depth_output_unit = DEFAULT_DEPTH_UNIT
         obj._batch_encoding_size = batch_encoding_size
 
         if obj._requested_root is not None:
@@ -823,12 +856,13 @@ class LeRobotDataset(torch.utils.data.Dataset):
         streaming_enc = None
         if streaming_encoding and len(obj.meta.video_keys) > 0:
             streaming_enc = cls._build_streaming_encoder(
-                obj.meta.fps, camera_encoder, encoder_queue_maxsize, encoder_threads
+                obj.meta.fps, rgb_encoder, depth_encoder, encoder_queue_maxsize, encoder_threads
             )
         obj.writer = DatasetWriter(
             meta=obj.meta,
             root=obj.root,
-            camera_encoder=camera_encoder,
+            rgb_encoder=rgb_encoder,
+            depth_encoder=depth_encoder,
             encoder_threads=encoder_threads,
             batch_encoding_size=batch_encoding_size,
             streaming_encoder=streaming_enc,

src/lerobot/datasets/pyav_utils.py

@@ -24,6 +24,7 @@ import logging
 from typing import Any
 
 import av
+import numpy as np
 
 logger = logging.getLogger(__name__)
 
@@ -31,6 +32,34 @@ FFMPEG_NUMERIC_OPTION_TYPES = ("INT", "INT64", "UINT64", "FLOAT", "DOUBLE")
 FFMPEG_INTEGER_OPTION_TYPES = ("INT", "INT64", "UINT64")
 
 
+def write_u16_plane(plane: av.video.plane.VideoPlane, src: np.ndarray, fill_value: int | None = None) -> None:
+    """Copy a 2D ``uint16`` image into the plane's memory buffer, row by row.
+
+    For speed, each row is padded to a wider size than ``width``, so the true row width in
+    memory is ``plane.line_size`` (bytes), not ``width``. Copying as one straight stream
+    would skew the image, so we write only the first ``width`` columns of each row and
+    leave the padding untouched.
+
+    Args:
+        plane: Destination 16-bit plane.
+        src: Source image, shape ``(height, width)``, dtype ``uint16``.
+        fill_value: If given, every pixel (padding included) is set to this first, so the
+            padding holds clean data instead of garbage.
+    """
+    height, width = src.shape
+    stride_u16 = plane.line_size // np.dtype(np.uint16).itemsize
+    dst = np.frombuffer(plane, dtype=np.uint16).reshape(height, stride_u16)
+    if fill_value is not None:
+        dst.fill(fill_value)
+    dst[:, :width] = src
+
+
+@functools.cache
+def get_pix_fmt_channels(pix_fmt: str) -> int:
+    """Return the number of components (channels) for *pix_fmt*."""
+    return len(av.VideoFormat(pix_fmt).components)
+
+
 @functools.cache
 def get_codec(vcodec: str) -> av.codec.Codec | None:
     """PyAV write-mode ``Codec`` for *vcodec*, or ``None`` if unavailable."""
@@ -92,7 +121,7 @@ def _check_option_value(vcodec: str, label: str, value: Any, opt: av.option.Opti
                     f"{label}={value!r} is not numeric; codec {vcodec!r} expects a number for this option."
                 ) from e
         elif isinstance(value, (float, int)):
-            num_val = value
+            num_val = float(value)
         else:
             raise ValueError(
                 f"{label}={value!r} is not numeric; codec {vcodec!r} expects a number for this option."
@@ -142,6 +171,16 @@ def _check_pixel_format(vcodec: str, pix_fmt: str) -> None:
         )
 
 
+def _check_pix_fmt_channels(pix_fmt: str, channels: int) -> None:
+    """Ensure *pix_fmt* can carry at least *channels* components."""
+    pix_fmt_channels = get_pix_fmt_channels(pix_fmt)
+    if pix_fmt_channels < channels:
+        raise ValueError(
+            f"pix_fmt={pix_fmt!r} carries only {pix_fmt_channels} component(s) "
+            f"but the source data has {channels} channel(s)."
+        )
+
+
 def _check_codec_options(vcodec: str, codec_options: dict[str, Any]) -> None:
     """Validate merged encoder options (typed) against the codec's published AVOptions."""
     supported_options = _get_codec_options_by_name(vcodec)
@@ -156,12 +195,18 @@ def _check_codec_options(vcodec: str, codec_options: dict[str, Any]) -> None:
         _check_option_value(vcodec, key, value, supported_options[key])
 
 
-def check_video_encoder_parameters_pyav(vcodec: str, pix_fmt: str, codec_options: dict[str, Any]) -> None:
+def check_video_encoder_parameters_pyav(
+    vcodec: str,
+    pix_fmt: str,
+    codec_options: dict[str, Any],
+    channels: int | None = None,
+) -> None:
     """Verify *config* is compatible with the bundled FFmpeg build.
 
     Checks pixel format, abstract tuning-field compatibility, and each merged
     encoder option from :meth:`~lerobot.configs.video.VideoEncoderConfig.get_codec_options`
     against PyAV (including numeric ``extra_options`` present in that dict).
+    When given, additionally verify that *pix_fmt* carries as many components as the source data channels.
     No-op when ``config.vcodec`` isn't in the local FFmpeg build.
 
     Raises:
@@ -171,4 +216,6 @@ def check_video_encoder_parameters_pyav(vcodec: str, pix_fmt: str, codec_options
     if not options:
         raise ValueError(f"Codec {vcodec!r} is not available in the bundled FFmpeg build")
     _check_pixel_format(vcodec, pix_fmt)
+    if channels is not None:
+        _check_pix_fmt_channels(pix_fmt, channels)
     _check_codec_options(vcodec, codec_options)

src/lerobot/datasets/sampler.py

@@ -53,6 +53,7 @@ class EpisodeAwareSampler:
         drop_n_last_frames: int = 0,
         shuffle: bool = False,
         seed: int = 0,
+        absolute_to_relative_idx: dict[int, int] | None = None,
     ):
         """
         Args:
@@ -107,6 +108,7 @@ class EpisodeAwareSampler:
         self.seed = seed
         self._epoch = 0
         self._start_index = 0
+        self._absolute_to_relative = absolute_to_relative_idx
 
     @property
     def indices(self) -> list[int]:
@@ -132,7 +134,10 @@ class EpisodeAwareSampler:
     def _frame_index(self, position: int) -> int:
         episode = int(np.searchsorted(self._cum_lengths, position, side="right"))
         position_in_episode = position - (int(self._cum_lengths[episode - 1]) if episode > 0 else 0)
-        return int(self._starts[episode]) + position_in_episode
+        absolute_idx = int(self._starts[episode]) + position_in_episode
+        if self._absolute_to_relative is not None:
+            return self._absolute_to_relative[absolute_idx]
+        return absolute_idx
 
     def __iter__(self) -> Iterator[int]:
         # Advance epoch state eagerly, not on first consumption of the generator.

src/lerobot/datasets/streaming_dataset.py

@@ -22,9 +22,11 @@ import numpy as np
 import torch
 from datasets import load_dataset
 
+from lerobot.configs import DEFAULT_DEPTH_UNIT, DepthEncoderConfig
 from lerobot.utils.constants import HF_LEROBOT_HOME, LOOKAHEAD_BACKTRACKTABLE, LOOKBACK_BACKTRACKTABLE
 
 from .dataset_metadata import CODEBASE_VERSION, LeRobotDatasetMetadata
+from .depth_utils import dequantize_depth
 from .feature_utils import get_delta_indices
 from .io_utils import item_to_torch
 from .utils import (
@@ -35,6 +37,7 @@ from .utils import (
 )
 from .video_utils import (
     VideoDecoderCache,
+    decode_video_frames,
     decode_video_frames_torchcodec,
 )
 
@@ -252,6 +255,7 @@ class StreamingLeRobotDataset(torch.utils.data.IterableDataset):
         rng: np.random.Generator | None = None,
         shuffle: bool = True,
         return_uint8: bool = False,
+        depth_output_unit: str = DEFAULT_DEPTH_UNIT,
     ):
         """Initialize a StreamingLeRobotDataset.
 
@@ -272,6 +276,8 @@ class StreamingLeRobotDataset(torch.utils.data.IterableDataset):
             seed (int, optional): Reproducibility random seed.
             rng (np.random.Generator | None, optional): Random number generator.
             shuffle (bool, optional): Whether to shuffle the dataset across exhaustions. Defaults to True.
+            depth_output_unit (str, optional): Physical unit depth maps are dequantized to ("m" or "mm").
+                Defaults to "mm".
         """
         super().__init__()
         self.repo_id = repo_id
@@ -290,6 +296,7 @@ class StreamingLeRobotDataset(torch.utils.data.IterableDataset):
         self.streaming = streaming
         self.buffer_size = buffer_size
         self._return_uint8 = return_uint8
+        self._depth_output_unit = depth_output_unit
 
         # We cache the video decoders to avoid re-initializing them at each frame (avoiding a ~10x slowdown)
         self.video_decoder_cache = None
@@ -306,6 +313,11 @@ class StreamingLeRobotDataset(torch.utils.data.IterableDataset):
         # Check version
         check_version_compatibility(self.repo_id, self.meta._version, CODEBASE_VERSION)
 
+        self._depth_encoder_configs: dict[str, DepthEncoderConfig] = {
+            vid_key: DepthEncoderConfig.from_video_info(self.meta.features[vid_key].get("info"))
+            for vid_key in self.meta.depth_keys
+        }
+
         self.delta_timestamps = None
         self.delta_indices = None
 
@@ -554,13 +566,34 @@ class StreamingLeRobotDataset(torch.utils.data.IterableDataset):
         for video_key, query_ts in query_timestamps.items():
             root = self.meta.url_root if self.streaming and not self.streaming_from_local else self.root
             video_path = f"{root}/{self.meta.get_video_file_path(ep_idx, video_key)}"
-            frames = decode_video_frames_torchcodec(
-                video_path,
-                query_ts,
-                self.tolerance_s,
-                decoder_cache=self.video_decoder_cache,
-                return_uint8=self._return_uint8,
-            )
+            if video_key in self.meta.depth_keys:
+                # Depth maps are 12-bit quantized and only decodable via pyav; dequantize back
+                # to physical units to match the non-streaming reader.
+                frames = decode_video_frames(
+                    video_path,
+                    query_ts,
+                    self.tolerance_s,
+                    backend="pyav",
+                    return_uint8=False,
+                    is_depth=True,
+                )
+                depth_encoder = self._depth_encoder_configs[video_key]
+                frames = dequantize_depth(
+                    frames,
+                    depth_min=depth_encoder.depth_min,
+                    depth_max=depth_encoder.depth_max,
+                    shift=depth_encoder.shift,
+                    use_log=depth_encoder.use_log,
+                    output_unit=self._depth_output_unit,
+                )
+            else:
+                frames = decode_video_frames_torchcodec(
+                    video_path,
+                    query_ts,
+                    self.tolerance_s,
+                    decoder_cache=self.video_decoder_cache,
+                    return_uint8=self._return_uint8,
+                )
 
             item[video_key] = frames.squeeze(0) if len(query_ts) == 1 else frames
 

src/lerobot/datasets/utils.py

@@ -87,11 +87,14 @@ DATA_DIR = "data"
 VIDEO_DIR = "videos"
 
 CHUNK_FILE_PATTERN = "chunk-{chunk_index:03d}/file-{file_index:03d}"
+IMAGE_FILE_PATTERN = "frame-{frame_index:06d}.png"
+DEPTH_FILE_PATTERN = "frame-{frame_index:06d}.tiff"
 DEFAULT_TASKS_PATH = "meta/tasks.parquet"
 DEFAULT_EPISODES_PATH = EPISODES_DIR + "/" + CHUNK_FILE_PATTERN + ".parquet"
 DEFAULT_DATA_PATH = DATA_DIR + "/" + CHUNK_FILE_PATTERN + ".parquet"
 DEFAULT_VIDEO_PATH = VIDEO_DIR + "/{video_key}/" + CHUNK_FILE_PATTERN + ".mp4"
-DEFAULT_IMAGE_PATH = "images/{image_key}/episode-{episode_index:06d}/frame-{frame_index:06d}.png"
+DEFAULT_IMAGE_PATH = "images/{image_key}/episode-{episode_index:06d}/" + IMAGE_FILE_PATTERN
+DEFAULT_DEPTH_PATH = "images/{image_key}/episode-{episode_index:06d}/" + DEPTH_FILE_PATTERN
 
 LEGACY_EPISODES_PATH = "meta/episodes.jsonl"
 LEGACY_EPISODES_STATS_PATH = "meta/episodes_stats.jsonl"

src/lerobot/datasets/video_utils.py

@@ -39,11 +39,17 @@ from datasets.features.features import register_feature
 from PIL import Image
 
 from lerobot.configs import (
+    DepthEncoderConfig,
+    RGBEncoderConfig,
     VideoEncoderConfig,
-    camera_encoder_defaults,
+    depth_encoder_defaults,
+    rgb_encoder_defaults,
 )
 from lerobot.utils.import_utils import get_safe_default_video_backend
 
+from .depth_utils import quantize_depth
+from .pyav_utils import get_pix_fmt_channels
+
 logger = logging.getLogger(__name__)
 
 
@@ -53,6 +59,7 @@ def decode_video_frames(
     tolerance_s: float,
     backend: str | None = None,
     return_uint8: bool = False,
+    is_depth: bool = False,
 ) -> torch.Tensor:
     """
     Decodes video frames using the specified backend.
@@ -64,23 +71,35 @@ def decode_video_frames(
         backend (str, optional): Backend to use for decoding. Defaults to "torchcodec" when available
             in the platform; otherwise, defaults to "pyav". The legacy value "video_reader" is
             accepted for one release as an alias for "pyav" and will be removed in a future version.
-        return_uint8 (bool): If True, return raw uint8 frames without float32 normalization.
+        return_uint8 (bool): For RGB videos, if True return raw uint8 frames without float32 normalization.
             This reduces memory for DataLoader IPC; normalization can be done on GPU afterward.
+        is_depth (bool): Set to True if the video is a depth map (1 channel, uint12).
 
     Returns:
-        torch.Tensor: Decoded frames (float32 in [0,1] by default, or uint8 if return_uint8=True).
+        torch.Tensor: Decoded frames (RGB: float32 in [0,1] by default, or uint8 if return_uint8=True, Depth: uint12).
 
     Currently supports torchcodec on cpu and pyav.
     """
+    if backend != "pyav" and is_depth:
+        logger.debug("Decoding depth maps is only supported with the 'pyav' backend, falling back to pyav.")
+        # We do not actually return uint8 here, but we avoid the 255 normalization step.
+        return decode_video_frames_pyav(
+            video_path, timestamps, tolerance_s, return_uint8=False, is_depth=True
+        )
+
     if backend is None:
         backend = get_safe_default_video_backend()
     if backend == "torchcodec":
         return decode_video_frames_torchcodec(video_path, timestamps, tolerance_s, return_uint8=return_uint8)
     elif backend == "pyav":
-        return decode_video_frames_pyav(video_path, timestamps, tolerance_s, return_uint8=return_uint8)
+        return decode_video_frames_pyav(
+            video_path, timestamps, tolerance_s, return_uint8=return_uint8, is_depth=is_depth
+        )
     elif backend == "video_reader":
         logger.warning("backend='video_reader' is deprecated and now aliases to 'pyav'.")
-        return decode_video_frames_pyav(video_path, timestamps, tolerance_s, return_uint8=return_uint8)
+        return decode_video_frames_pyav(
+            video_path, timestamps, tolerance_s, return_uint8=return_uint8, is_depth=is_depth
+        )
     else:
         raise ValueError(f"Unsupported video backend: {backend}")
 
@@ -91,6 +110,7 @@ def decode_video_frames_pyav(
     tolerance_s: float,
     log_loaded_timestamps: bool = False,
     return_uint8: bool = False,
+    is_depth: bool = False,
 ) -> torch.Tensor:
     """Loads frames associated to the requested timestamps of a video using PyAV.
 
@@ -109,8 +129,9 @@ def decode_video_frames_pyav(
         tolerance_s: Allowed deviation in seconds between a queried timestamp and the closest
             decoded frame.
         log_loaded_timestamps: When True, log every decoded frame's timestamp at INFO level.
-        return_uint8: When True, return raw uint8 frames (C, H, W). Otherwise, return float32 in
-            [0, 1] range.
+        return_uint8: For RGB videos, if True return raw uint8 frames (C, H, W).
+            Otherwise, return float32 in [0, 1] range.
+        is_depth: Set to True if the video is a depth map (1 channel, uint12).
 
     Returns:
         torch.Tensor of shape (len(timestamps), C, H, W).
@@ -132,7 +153,13 @@ def decode_video_frames_pyav(
     # https://pyav.basswood-io.com/docs/stable/api/container.html#av.container.InputContainer.seek
     with av.open(video_path) as container:
         stream = container.streams.video[0]
-        container.seek(int(first_ts * av.time_base), backward=True)
+        # Seek to the nearest keyframe at or before `first_ts` with a 1 frame margin
+        container.seek(
+            round(first_ts / stream.time_base) - 1,
+            backward=True,
+            any_frame=False,
+            stream=stream,
+        )
 
         for frame in container.decode(stream):
             if frame.pts is None:
@@ -140,9 +167,13 @@ def decode_video_frames_pyav(
             current_ts = float(frame.pts * stream.time_base)
             if log_loaded_timestamps:
                 logger.info(f"frame loaded at timestamp={current_ts:.4f}")
-            # Convert to CHW uint8 to match torchcodec's output layout.
-            arr = frame.to_ndarray(format="rgb24")  # H, W, 3
-            loaded_frames.append(torch.from_numpy(arr).permute(2, 0, 1).contiguous())
+            if is_depth:
+                arr = frame.to_ndarray(format="gray12le")  # (H, W) uint12
+                loaded_frames.append(torch.from_numpy(arr).unsqueeze(0).contiguous())
+            else:
+                arr = frame.to_ndarray(format="rgb24")  # (H, W, 3)
+                # Convert to CHW uint8 to match torchcodec's output layout.
+                loaded_frames.append(torch.from_numpy(arr).permute(2, 0, 1).contiguous())
             loaded_ts.append(current_ts)
             if current_ts >= last_ts:
                 break
@@ -185,7 +216,7 @@ def decode_video_frames_pyav(
             f"number of queried timestamps ({len(timestamps)})"
         )
 
-    if return_uint8:
+    if return_uint8 or is_depth:
         return closest_frames
 
     # convert to the pytorch format which is float32 in [0,1] range (and channel first)
@@ -406,17 +437,38 @@ def encode_video_frames(
     imgs_dir: Path | str,
     video_path: Path | str,
     fps: int,
-    camera_encoder: VideoEncoderConfig | None = None,
+    video_encoder: VideoEncoderConfig | None = None,
     encoder_threads: int | None = None,
     *,
     log_level: int | None = av.logging.WARNING,
     overwrite: bool = False,
 ) -> None:
-    """More info on ffmpeg arguments tuning on `benchmark/video/README.md`"""
-    if camera_encoder is None:
-        camera_encoder = camera_encoder_defaults()
-    vcodec = camera_encoder.vcodec
-    pix_fmt = camera_encoder.pix_fmt
+    """Encode a directory of image frames into an MP4 video.
+
+    When ``video_encoder`` is a :class:`~lerobot.configs.video.DepthEncoderConfig`,
+    frames are read from ``.tiff`` files and quantized to 12-bit depth codes using the
+    encoder's ``depth_min`` / ``depth_max`` / ``shift`` / ``use_log``; otherwise ``.png``
+    RGB frames are encoded directly.
+
+    Args:
+        imgs_dir: Directory containing the frames to encode, named ``frame-000000``
+            onwards (``.png`` for RGB, ``.tiff`` for depth).
+        video_path: Output path for the encoded ``.mp4`` file.
+        fps: Frame rate of the output video.
+        video_encoder: Encoder settings (codec, pixel format, quality, ...). When
+            ``None``, :func:`rgb_encoder_defaults` is used. Pass a
+            :class:`~lerobot.configs.video.DepthEncoderConfig` to encode depth frames.
+        encoder_threads: Per-encoder thread count forwarded to the codec. ``None``
+            lets the codec decide.
+        log_level: libav log level to set while encoding, or ``None`` to leave the
+            current logging configuration unchanged.
+        overwrite: When ``False`` and ``video_path`` already exists, skip encoding and
+            log a warning. When ``True``, re-encode and replace the existing file.
+    """
+    if video_encoder is None:
+        video_encoder = rgb_encoder_defaults()
+    vcodec = video_encoder.vcodec
+    pix_fmt = video_encoder.pix_fmt
 
     video_path = Path(video_path)
     imgs_dir = Path(imgs_dir)
@@ -428,17 +480,19 @@ def encode_video_frames(
     video_path.parent.mkdir(parents=True, exist_ok=True)
 
     # Get input frames
-    template = "frame-" + ("[0-9]" * 6) + ".png"
+    is_depth = isinstance(video_encoder, DepthEncoderConfig)
+    suffix = ".png" if not is_depth else ".tiff"
+    template = "frame-" + ("[0-9]" * 6) + suffix
     input_list = sorted(
         glob.glob(str(imgs_dir / template)), key=lambda x: int(x.split("-")[-1].split(".")[0])
     )
 
     if len(input_list) == 0:
-        raise FileNotFoundError(f"No images found in {imgs_dir}.")
+        raise FileNotFoundError(f"No images with suffix {suffix} found in {imgs_dir}.")
     with Image.open(input_list[0]) as dummy_image:
         width, height = dummy_image.size
 
-    video_options = camera_encoder.get_codec_options(encoder_threads, as_strings=True)
+    video_options = video_encoder.get_codec_options(encoder_threads, as_strings=True)
 
     # Set logging level
     if log_level is not None:
@@ -455,8 +509,19 @@ def encode_video_frames(
         # Loop through input frames and encode them
         for input_data in input_list:
             with Image.open(input_data) as input_image:
-                input_image = input_image.convert("RGB")
-                input_frame = av.VideoFrame.from_image(input_image)
+                if is_depth:
+                    input_frame = quantize_depth(
+                        np.array(input_image),
+                        depth_min=video_encoder.depth_min,
+                        depth_max=video_encoder.depth_max,
+                        shift=video_encoder.shift,
+                        use_log=video_encoder.use_log,
+                        pix_fmt=video_encoder.pix_fmt,
+                        video_backend="pyav",
+                    )
+                else:
+                    input_image = input_image.convert("RGB")
+                    input_frame = av.VideoFrame.from_image(input_image)
                 packet = output_stream.encode(input_frame)
                 if packet:
                     output.mux(packet)
@@ -477,7 +542,7 @@ def encode_video_frames(
 def reencode_video(
     input_video_path: Path | str,
     output_video_path: Path | str,
-    camera_encoder: VideoEncoderConfig | None = None,
+    video_encoder: VideoEncoderConfig | None = None,
     encoder_threads: int | None = None,
     log_level: int | None = av.logging.WARNING,
     overwrite: bool = False,
@@ -489,7 +554,7 @@ def reencode_video(
     Args:
         input_video_path: Existing video file to read.
         output_video_path: Path for the re-encoded file.
-        camera_encoder: Encoder configuration. Defaults to :func:`camera_encoder_defaults`.
+        video_encoder: Encoder configuration. Defaults to :func:`rgb_encoder_defaults`.
         encoder_threads: Optional thread count forwarded to :meth:`VideoEncoderConfig.get_codec_options`.
         log_level: libav log level while encoding, or ``None`` to leave logging unchanged. Defaults to WARNING.
         overwrite: When ``False`` and ``output_video_path`` already exists, skip and log a warning.
@@ -497,7 +562,7 @@ def reencode_video(
         end_time_s: When set, trim the output to end at this timestamp (seconds, exclusive).
     """
 
-    camera_encoder = camera_encoder or camera_encoder_defaults()
+    video_encoder = video_encoder or rgb_encoder_defaults()
 
     if (start_time_s is not None and start_time_s < 0) or (end_time_s is not None and end_time_s < 0):
         raise ValueError(f"Trim times must be non-negative, got start={start_time_s}, end={end_time_s}.")
@@ -512,9 +577,9 @@ def reencode_video(
 
     output_video_path.parent.mkdir(parents=True, exist_ok=True)
 
-    video_options = camera_encoder.get_codec_options(encoder_threads, as_strings=True)
-    vcodec = camera_encoder.vcodec
-    pix_fmt = camera_encoder.pix_fmt
+    video_options = video_encoder.get_codec_options(encoder_threads, as_strings=True)
+    vcodec = video_encoder.vcodec
+    pix_fmt = video_encoder.pix_fmt
 
     with tempfile.NamedTemporaryFile(suffix=".mp4", delete=False) as tmp_named_file:
         tmp_output_video_path = tmp_named_file.name
@@ -696,22 +761,21 @@ class _CameraEncoderThread(threading.Thread):
         self,
         video_path: Path,
         fps: int,
-        vcodec: str,
-        pix_fmt: str,
-        codec_options: dict[str, str],
+        video_encoder: VideoEncoderConfig,
         frame_queue: queue.Queue,
         result_queue: queue.Queue,
         stop_event: threading.Event,
+        encoder_threads: int | None = None,
     ):
         super().__init__(daemon=True)
         self.video_path = video_path
         self.fps = fps
-        self.vcodec = vcodec
-        self.pix_fmt = pix_fmt
-        self.codec_options = codec_options
+        self.video_encoder = video_encoder
+        self.is_depth = isinstance(video_encoder, DepthEncoderConfig)
         self.frame_queue = frame_queue
         self.result_queue = result_queue
         self.stop_event = stop_event
+        self.encoder_threads = encoder_threads
 
     def run(self) -> None:
         from .compute_stats import RunningQuantileStats, auto_downsample_height_width
@@ -736,12 +800,12 @@ class _CameraEncoderThread(threading.Thread):
                     # Sentinel: flush and close
                     break
 
-                # Ensure HWC uint8 numpy array
+                # Ensure HWC (RGB or depth) uint8 (RGB only) numpy array
                 if isinstance(frame_data, np.ndarray):
-                    if frame_data.ndim == 3 and frame_data.shape[0] == 3:
+                    if frame_data.ndim == 3 and frame_data.shape[0] in (1, 3):
                         # CHW -> HWC
                         frame_data = frame_data.transpose(1, 2, 0)
-                    if frame_data.dtype != np.uint8:
+                    if not self.is_depth and frame_data.dtype != np.uint8:
                         frame_data = (frame_data * 255).astype(np.uint8)
 
                 # Open container on first frame (to get width/height)
@@ -749,15 +813,29 @@ class _CameraEncoderThread(threading.Thread):
                     height, width = frame_data.shape[:2]
                     Path(self.video_path).parent.mkdir(parents=True, exist_ok=True)
                     container = av.open(str(self.video_path), "w")
-                    output_stream = container.add_stream(self.vcodec, self.fps, options=self.codec_options)
-                    output_stream.pix_fmt = self.pix_fmt
+                    output_stream = container.add_stream(
+                        self.video_encoder.vcodec,
+                        self.fps,
+                        options=self.video_encoder.get_codec_options(self.encoder_threads, as_strings=True),
+                    )
+                    output_stream.pix_fmt = self.video_encoder.pix_fmt
                     output_stream.width = width
                     output_stream.height = height
                     output_stream.time_base = Fraction(1, self.fps)
 
                 # Encode frame with explicit timestamps
-                pil_img = Image.fromarray(frame_data)
-                video_frame = av.VideoFrame.from_image(pil_img)
+                if not self.is_depth:
+                    pil_img = Image.fromarray(frame_data)
+                    video_frame = av.VideoFrame.from_image(pil_img)
+                else:
+                    video_frame = quantize_depth(
+                        frame_data,
+                        depth_min=self.video_encoder.depth_min,
+                        depth_max=self.video_encoder.depth_max,
+                        shift=self.video_encoder.shift,
+                        use_log=self.video_encoder.use_log,
+                        video_backend=self.video_encoder.video_backend,
+                    )
                 video_frame.pts = frame_count
                 video_frame.time_base = Fraction(1, self.fps)
                 packet = output_stream.encode(video_frame)
@@ -815,22 +893,27 @@ class StreamingVideoEncoder:
     def __init__(
         self,
         fps: int,
-        camera_encoder: VideoEncoderConfig | None = None,
+        rgb_encoder: RGBEncoderConfig | None = None,
+        depth_encoder: DepthEncoderConfig | None = None,
         queue_maxsize: int = 30,
         encoder_threads: int | None = None,
     ):
         """
         Args:
             fps: Frames per second for the output videos.
-            camera_encoder: Video encoder settings applied to all cameras.
-                When ``None``, :func:`camera_encoder_defaults` is used.
-            encoder_threads: Number of encoder threads (global setting).
-                ``None`` lets the codec decide.
+            rgb_encoder: Video encoder settings applied to all RGB cameras.
+                When ``None``, :func:`rgb_encoder_defaults` is used.
+            depth_encoder: Video encoder settings applied to all depth cameras,
+                including the depth quantization parameters. When ``None``,
+                :func:`depth_encoder_defaults` is used.
             queue_maxsize: Max frames to buffer per camera before
                 back-pressure drops frames.
+            encoder_threads: Number of encoder threads (global setting).
+                ``None`` lets the codec decide.
         """
         self.fps = fps
-        self._camera_encoder = camera_encoder or camera_encoder_defaults()
+        self._rgb_encoder = rgb_encoder or rgb_encoder_defaults()
+        self._depth_encoder = depth_encoder or depth_encoder_defaults()
         self._encoder_threads = encoder_threads
         self.queue_maxsize = queue_maxsize
 
@@ -843,18 +926,25 @@ class StreamingVideoEncoder:
         self._episode_active = False
         self._closed = False
 
-    def start_episode(self, video_keys: list[str], temp_dir: Path) -> None:
+    def start_episode(
+        self, video_keys: list[str], temp_dir: Path, depth_video_keys: list[str] | None = None
+    ) -> None:
         """Start encoder threads for a new episode.
 
         Args:
             video_keys: List of video feature keys (e.g. ["observation.images.laptop"])
             temp_dir: Base directory for temporary MP4 files
+            depth_video_keys: List of video or image feature keys that carry depth maps (e.g.
+                ["observation.images.laptop_depth"]).  Defaults to ``[]`` (no depth keys).
         """
         if self._episode_active:
             self.cancel_episode()
 
         self._dropped_frames.clear()
 
+        if depth_video_keys is None:
+            depth_video_keys = []
+
         for video_key in video_keys:
             frame_queue: queue.Queue = queue.Queue(maxsize=self.queue_maxsize)
             result_queue: queue.Queue = queue.Queue(maxsize=1)
@@ -863,17 +953,15 @@ class StreamingVideoEncoder:
             temp_video_dir = Path(tempfile.mkdtemp(dir=temp_dir))
             video_path = temp_video_dir / f"{video_key.replace('/', '_')}_streaming.mp4"
 
-            vcodec = self._camera_encoder.vcodec
-            codec_options = self._camera_encoder.get_codec_options(self._encoder_threads, as_strings=True)
+            encoder = self._depth_encoder if video_key in depth_video_keys else self._rgb_encoder
             encoder_thread = _CameraEncoderThread(
                 video_path=video_path,
                 fps=self.fps,
-                vcodec=vcodec,
-                pix_fmt=self._camera_encoder.pix_fmt,
-                codec_options=codec_options,
+                video_encoder=encoder,
                 frame_queue=frame_queue,
                 result_queue=result_queue,
                 stop_event=stop_event,
+                encoder_threads=self._encoder_threads,
             )
             encoder_thread.start()
 
@@ -1080,15 +1168,23 @@ def get_audio_info(video_path: Path | str) -> dict:
 
 def get_video_info(
     video_path: Path | str,
-    camera_encoder: VideoEncoderConfig | None = None,
+    video_encoder: VideoEncoderConfig | None = None,
 ) -> dict:
     """Build the ``video.*`` / ``audio.*`` info dict persisted in ``info.json``.
 
     Args:
         video_path: Path to the encoded video file to probe.
-        camera_encoder: If provided, record the exact encoder settings used to encode this
+        video_encoder: If provided, record the exact encoder settings used to encode this
             video. Stream-derived values take precedence — encoder fields are only written for keys
-            not already populated from the video file itself.
+            not already populated from the video file itself. When a
+            :class:`~lerobot.configs.video.DepthEncoderConfig` is passed, the depth
+            quantization parameters (``depth_min`` / ``depth_max`` / ``shift`` /
+            ``use_log``) are recorded so frames can be dequantized on read.
+
+    Returns:
+        The ``video.*`` / ``audio.*`` info dict, including ``is_depth_map`` which is
+        ``True`` only when ``video_encoder`` is a
+        :class:`~lerobot.configs.video.DepthEncoderConfig`.
     """
     logging.getLogger("libav").setLevel(av.logging.WARNING)
 
@@ -1106,13 +1202,10 @@ def get_video_info(
         video_info["video.width"] = video_stream.width
         video_info["video.codec"] = video_stream.codec.canonical_name
         video_info["video.pix_fmt"] = video_stream.pix_fmt
-        video_info["video.is_depth_map"] = False
 
         # Calculate fps from r_frame_rate
         video_info["video.fps"] = int(video_stream.base_rate)
-
-        pixel_channels = get_video_pixel_channels(video_stream.pix_fmt)
-        video_info["video.channels"] = pixel_channels
+        video_info["video.channels"] = get_pix_fmt_channels(video_stream.pix_fmt)
 
     # Reset logging level
     av.logging.restore_default_callback()
@@ -1121,27 +1214,18 @@ def get_video_info(
     video_info.update(**get_audio_info(video_path))
 
     # Add additional encoder configuration if provided
-    if camera_encoder is not None:
-        for field_name, field_value in asdict(camera_encoder).items():
+    if video_encoder is not None:
+        for field_name, field_value in asdict(video_encoder).items():
             # vcodec is already populated from the video stream
             if field_name == "vcodec":
                 continue
             video_info.setdefault(f"video.{field_name}", field_value)
 
+    video_info["is_depth_map"] = isinstance(video_encoder, DepthEncoderConfig)
+
     return video_info
 
 
-def get_video_pixel_channels(pix_fmt: str) -> int:
-    if "gray" in pix_fmt or "depth" in pix_fmt or "monochrome" in pix_fmt:
-        return 1
-    elif "rgba" in pix_fmt or "yuva" in pix_fmt:
-        return 4
-    elif "rgb" in pix_fmt or "yuv" in pix_fmt:
-        return 3
-    else:
-        raise ValueError("Unknown format")
-
-
 def get_video_duration_in_s(video_path: Path | str) -> float:
     """
     Get the duration of a video file in seconds using PyAV.
@@ -1202,10 +1286,13 @@ class VideoEncodingManager:
         img_dir = self.dataset.root / "images"
         if img_dir.exists():
             png_files = list(img_dir.rglob("*.png"))
-            if len(png_files) == 0:
+            tiff_files = list(img_dir.rglob("*.tiff"))
+            if len(png_files) == 0 and len(tiff_files) == 0:
                 shutil.rmtree(img_dir)
                 logger.debug("Cleaned up empty images directory")
             else:
-                logger.debug(f"Images directory is not empty, containing {len(png_files)} PNG files")
+                logger.debug(
+                    f"Images directory is not empty, containing {len(png_files)} PNG and {len(tiff_files)} TIFF files"
+                )
 
         return False  # Don't suppress the original exception

src/lerobot/jobs/__init__.py

@@ -0,0 +1,23 @@
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from lerobot.utils.import_utils import require_package
+
+# LeRobotDataset (imported at module top in dataset.py) pulls in heavy dataset deps;
+# guard the optional dependency here so importing this package fails loudly if it's missing.
+require_package("datasets", extra="dataset")
+
+from .hf import submit_to_hf
+
+__all__ = ["submit_to_hf"]

src/lerobot/jobs/dataset.py

@@ -0,0 +1,53 @@
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Make a training dataset reachable from an HF Job pod.
+
+The pod can't see the host's ~/.cache/huggingface/lerobot, so the dataset has to
+live on the Hub: the pod downloads it by repo_id at train time (the forwarded
+HF_TOKEN covers private datasets). A dataset already on the Hub is used as-is; a
+local-only dataset is pushed to a PRIVATE repo first (never public).
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from lerobot.datasets import LeRobotDataset
+from lerobot.utils.constants import HF_LEROBOT_HOME
+
+if TYPE_CHECKING:
+    from huggingface_hub import HfApi
+
+
+def ensure_dataset_available(repo_id: str, *, api: HfApi, tags: list[str] | None = None) -> None:
+    """Ensure repo_id resolves on the Hub, pushing a local-only dataset privately first.
+
+    `tags` are attached to the dataset only when we push it (an already-on-Hub
+    dataset is left untouched). Raises RuntimeError if the dataset is neither on
+    the Hub nor in the local cache.
+    """
+    if api.repo_exists(repo_id, repo_type="dataset"):
+        return
+
+    local_present = (HF_LEROBOT_HOME / repo_id / "meta" / "info.json").is_file()
+    if not local_present:
+        raise RuntimeError(
+            f"Dataset '{repo_id}' is not in the local cache ({HF_LEROBOT_HOME}) and could not be "
+            f"reached on the Hub — it may not exist, or be private and inaccessible with your "
+            f"token. Record or download it first, or run `hf auth login`."
+        )
+
+    print(f"[dataset] '{repo_id}' is local-only; pushing to a PRIVATE Hub repo...")
+    LeRobotDataset(repo_id).push_to_hub(private=True, tags=tags)
+    print(f"[dataset] '{repo_id}' uploaded (private). The job will download it by repo_id.")

src/lerobot/jobs/hf.py

@@ -0,0 +1,425 @@
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Run a lerobot training on HF Jobs (HuggingFace GPUs).
+
+Ported and simplified from lelab's runners/hf_cloud.py: no UI log queue, no
+registry — just submit and stream to stdout.
+"""
+
+from __future__ import annotations
+
+import copy
+import datetime as dt
+import json
+import netrc
+import os
+import re
+import signal
+import sys
+import tempfile
+import threading
+from pathlib import Path
+from typing import TYPE_CHECKING
+
+import httpx
+from huggingface_hub import (
+    HfApi,
+    create_repo,
+    fetch_job_logs,
+    get_token,
+    inspect_job,
+    run_job,
+    upload_file,
+)
+
+from lerobot.common.train_utils import push_checkpoint_to_hub
+from lerobot.configs import parser
+
+from .dataset import ensure_dataset_available
+
+if TYPE_CHECKING:
+    from lerobot.configs.train import TrainPipelineConfig
+
+_SLUG_RE = re.compile(r"[^a-zA-Z0-9._-]+")
+
+_TERMINAL_STAGES = {"COMPLETED", "CANCELED", "ERROR", "DELETED"}
+
+# huggingface_hub 1.x runs on httpx: transient HTTP/transport failures surface as
+# httpx.HTTPError and socket-level errors as OSError. Catching only these keeps real
+# bugs (TypeError, AttributeError, ...) from being silently retried or counted as
+# job failures.
+_TRANSIENT_NET_ERRORS = (OSError, httpx.HTTPError)
+
+# Always attached to remote jobs and pushed datasets so LeRobot-originated work
+# is identifiable on the Hub; callers (e.g. LeLab) add their own via --job.tags.
+LEROBOT_TAG = "lerobot"
+
+
+def resolve_job_tags(extra: list[str] | None) -> list[str]:
+    """Return the tag list for a run: the lerobot tag plus any extras, deduped, order-stable."""
+    tags = [LEROBOT_TAG, *(extra or [])]
+    seen: set[str] = set()
+    return [t for t in tags if not (t in seen or seen.add(t))]
+
+
+def resolve_wandb_api_key() -> str | None:
+    """Host's wandb key for forwarding to the job: $WANDB_API_KEY, else ~/.netrc."""
+    key = os.environ.get("WANDB_API_KEY")
+    if key:
+        return key
+    try:
+        rc = netrc.netrc()
+    except (FileNotFoundError, netrc.NetrcParseError, OSError):
+        return None
+    auth = rc.authenticators("api.wandb.ai")
+    if auth is None:
+        return None
+    _login, _account, password = auth
+    return password or None
+
+
+def build_repo_id(username: str, job_name: str, now: dt.datetime) -> str:
+    """Generate the model repo id for a remote run: <user>/<job_name>_<timestamp>."""
+    slug = _SLUG_RE.sub("-", job_name).strip("-") or "train"
+    stamp = now.strftime("%Y-%m-%d_%H-%M-%S")
+    return f"{username}/{slug}_{stamp}"
+
+
+def build_remote_config_file(cfg, repo_id: str, dest: Path, tags: list[str] | None = None) -> Path:
+    """Write a train_config.json for the pod, with remote overrides applied.
+
+    The pod runs `lerobot-train --config_path=<dest>` and downloads the dataset
+    by repo_id into its own cache. Client-only fields are stripped so the config
+    is accepted by the trainer image: `job` (pure client orchestration) is always
+    removed, and `save_checkpoint_to_hub` is removed unless explicitly enabled —
+    older lerobot images reject unknown keys, so the default keeps the config
+    compatible with the released `lerobot-gpu` image. `tags` are merged into
+    policy.tags so the trained model the pod pushes carries them too.
+    """
+    remote = copy.deepcopy(cfg)
+    remote.policy.push_to_hub = True
+    remote.policy.repo_id = repo_id
+    # Don't pin the client's resolved device (e.g. "mps"); let the pod auto-detect its GPU.
+    remote.policy.device = None
+    # Drop any host-local dataset root; the pod resolves the dataset by repo_id.
+    remote.dataset.root = None
+    if tags:
+        existing = list(remote.policy.tags or [])
+        remote.policy.tags = existing + [t for t in tags if t not in existing]
+
+    # Encode to the canonical, pod-parseable dict, then drop the keys the released
+    # trainer image doesn't know about.
+    data = remote.to_dict()
+    data.pop("job", None)
+    if not remote.save_checkpoint_to_hub:
+        data.pop("save_checkpoint_to_hub", None)
+
+    dest.parent.mkdir(parents=True, exist_ok=True)
+    dest.write_text(json.dumps(data, indent=4))
+    return dest
+
+
+def _stage_config_on_hub(cfg, repo_id: str, token: str, tags: list[str] | None = None) -> str:
+    """Upload train_config.json to the model repo and return the repo_id for --config_path."""
+    create_repo(repo_id, repo_type="model", private=True, exist_ok=True, token=token)
+    with tempfile.TemporaryDirectory() as tmp:
+        config_path = build_remote_config_file(cfg, repo_id, Path(tmp) / "train_config.json", tags=tags)
+        upload_file(
+            path_or_fileobj=config_path,
+            path_in_repo="train_config.json",
+            repo_id=repo_id,
+            repo_type="model",
+            token=token,
+        )
+    return repo_id
+
+
+def _tail_logs(
+    job_id: str,
+    done: threading.Event,
+    success_marker: str | None = None,
+    success_event: threading.Event | None = None,
+) -> None:
+    """Stream job logs to stdout, reconnecting on dropped streams until done is set.
+
+    Each reconnect re-fetches the full buffered log, so we track how many lines
+    were already printed and skip them — otherwise a fast-failing job's traceback
+    gets reprinted on every reconnect.
+
+    When `success_marker` appears in a line, set `success_event` and `done` so the
+    caller can finish as soon as the trained model lands on the Hub, rather than
+    waiting out the platform's post-run finalization (which can add ~30s).
+    """
+    printed = 0
+    while not done.is_set():
+        try:
+            seen = 0
+            for line in fetch_job_logs(job_id=job_id, follow=True):
+                seen += 1
+                if seen <= printed:
+                    continue  # already shown on a previous connection
+                printed = seen
+                # fetch_job_logs yields SSE data without trailing newlines, so add one
+                # per entry — otherwise all log lines concatenate onto a single line.
+                print(line.rstrip("\n"), flush=True)
+                if success_marker and success_event is not None and success_marker in line:
+                    success_event.set()
+                    done.set()
+                    return
+                if done.is_set():
+                    return
+            # Stream closed cleanly. Wait a moment so the status poller can mark
+            # the job terminal before we reconnect (avoids re-tailing the buffer).
+            if done.wait(3):
+                return
+        except _TRANSIENT_NET_ERRORS:
+            if done.wait(2):
+                return
+
+
+def _poll_until_done(
+    job_id: str,
+    done: threading.Event,
+    poll_interval: float = 5.0,
+    status_holder: dict | None = None,
+    max_failures: int = 6,
+) -> str | None:
+    """Poll inspect_job until a terminal stage or until `done` is set.
+
+    Returns the terminal stage string, or None if `done` was set first (detach)
+    or after `max_failures` consecutive inspect_job errors. When a terminal stage
+    is reached and `status_holder` is given, records `status_holder["message"]`
+    (the platform's status message, e.g. "Job timeout").
+    """
+    failures = 0
+    while not done.is_set():
+        try:
+            info = inspect_job(job_id=job_id)
+            failures = 0
+            # `stage` is an enum in some huggingface_hub versions and a plain str in others.
+            stage = getattr(info.status.stage, "value", info.status.stage)
+            if stage in _TERMINAL_STAGES:
+                if status_holder is not None:
+                    status_holder["message"] = getattr(info.status, "message", None)
+                done.set()
+                return stage
+        except _TRANSIENT_NET_ERRORS:
+            failures += 1
+            if failures >= max_failures:
+                done.set()
+                return None
+        done.wait(poll_interval)
+    return None
+
+
+def _pod_forwarded_args(
+    argv: list[str], drop_names: tuple[str, ...] = (), drop_prefixes: tuple[str, ...] = ()
+) -> list[str]:
+    """User CLI overrides to replay on the pod, minus flags the submitter sets itself.
+
+    Handles both `--name=value` and `--name value` forms. Forwarding the user's overrides (e.g.
+    `--steps`, `--save_checkpoint_to_hub`) makes a remote resume behave like the same local command.
+    """
+    out: list[str] = []
+    skip_next = False
+    for i, tok in enumerate(argv):
+        if skip_next:
+            skip_next = False
+            continue
+        name = tok.split("=", 1)[0]
+        if name in drop_names or any(name.startswith(p) for p in drop_prefixes):
+            if "=" not in tok and i + 1 < len(argv) and not argv[i + 1].startswith("--"):
+                skip_next = True  # also drop the space-separated value
+            continue
+        out.append(tok)
+    return out
+
+
+def _build_resume_job(cfg: TrainPipelineConfig, username: str) -> tuple[str, list[str]]:
+    """Resolve the model repo and pod command to resume a run on a job.
+
+    A Hub `config_path` is resumed from directly: its checkpoint config already targets that repo,
+    so new checkpoints continue the lineage there. A local `config_path` has its checkpoint uploaded
+    to a new PRIVATE repo first, and the resumed run is forced to push back to it. The pod command
+    always carries `--job.target=local` so the checkpoint's saved `job.target` can't make the pod
+    re-dispatch itself.
+    """
+    config_path = parser.parse_arg("config_path")
+    forwarded = _pod_forwarded_args(
+        sys.argv[1:],
+        drop_names=("--config_path", "--policy.repo_id", "--policy.push_to_hub", "--dataset.root"),
+        drop_prefixes=("--job.",),
+    )
+
+    if Path(config_path).exists():
+        # Local checkpoint: stage it on the Hub so the pod can resume from it, and push back there.
+        # Resolve so a `last` symlink uploads under its real step name (digit), which the pod's
+        # latest-checkpoint lookup keys on.
+        checkpoint_dir = Path(cfg.checkpoint_path).resolve()
+        source_repo = build_repo_id(username, cfg.job_name or "train", dt.datetime.now(dt.UTC))
+        push_checkpoint_to_hub(checkpoint_dir, source_repo, private=True)
+        extra = [f"--policy.repo_id={source_repo}", "--policy.push_to_hub=true"]
+    else:
+        source_repo = config_path
+        extra = []
+
+    command = [
+        "lerobot-train",
+        *forwarded,
+        f"--config_path={source_repo}",
+        "--job.target=local",
+        *extra,
+    ]
+    return source_repo, command
+
+
+def submit_to_hf(cfg: TrainPipelineConfig) -> None:
+    """Submit a training job to HF Jobs infrastructure.
+
+    Validates cfg, resolves credentials, ensures the dataset is on the Hub, then either stages a
+    sanitized config (fresh run) or resumes from a checkpoint repo, submits the job, and tails logs
+    until completion or detaches immediately. Ctrl-C detaches without cancelling the remote job.
+    """
+    token = get_token()
+    if not token:
+        raise RuntimeError("Not logged in to Hugging Face. Run `hf auth login` first.")
+
+    api = HfApi(token=token)
+    user_info = api.whoami(token=token)
+    username = user_info["name"]
+
+    now = dt.datetime.now(dt.UTC)
+    fresh_repo_id: str | None = None
+    if not cfg.resume:
+        # Resolve the model repo and mark it for push BEFORE validate(): validate() requires repo_id
+        # to be set whenever push_to_hub is True. (A resume reuses the checkpoint's repo instead.)
+        if cfg.policy is not None:
+            base_name = cfg.job_name or cfg.policy.type
+            fresh_repo_id = cfg.policy.repo_id or build_repo_id(username, base_name, now)
+            cfg.policy.repo_id = fresh_repo_id
+            cfg.policy.push_to_hub = True
+        else:
+            # Path-based policy is resolved inside validate(); fall back to a generic slug.
+            fresh_repo_id = build_repo_id(username, cfg.job_name or "train", now)
+
+    cfg.validate()
+
+    if cfg.is_reward_model_training:
+        raise ValueError(
+            "Remote training via --job.target only supports policy training, not reward models. "
+            "Run reward-model training locally."
+        )
+
+    secrets: dict[str, str] = {"HF_TOKEN": token}
+    if cfg.wandb.enable:
+        wandb_key = resolve_wandb_api_key()
+        if wandb_key is None:
+            raise ValueError(
+                "wandb is enabled but no WANDB_API_KEY found. "
+                "Set it via `export WANDB_API_KEY=...` or add it to ~/.netrc."
+            )
+        secrets["WANDB_API_KEY"] = wandb_key
+
+    tags = resolve_job_tags(cfg.job.tags)
+    # The dataset must be reachable from the pod for both fresh and resumed runs; a local-only
+    # dataset is pushed PRIVATE here. Hoisted before the resume/fresh branch since it applies to both.
+    ensure_dataset_available(cfg.dataset.repo_id, api=api, tags=tags)
+
+    if cfg.resume:
+        repo_id, command = _build_resume_job(cfg, username)
+    else:
+        config_repo_id = _stage_config_on_hub(cfg, fresh_repo_id, token, tags=tags)
+        repo_id = fresh_repo_id
+        command = ["lerobot-train", f"--config_path={config_repo_id}"]
+
+    print(f"Submitting job to HF Jobs (flavor={cfg.job.target}, image={cfg.job.image}) ...")
+    job_info = run_job(
+        image=cfg.job.image,
+        command=command,
+        flavor=cfg.job.target,
+        secrets=secrets,
+        timeout=cfg.job.timeout,
+        # HF Jobs labels are key/value; expose each tag as a queryable label.
+        labels=dict.fromkeys(tags, "true"),
+    )
+    job_id = job_info.id
+    job_url = getattr(job_info, "url", None)
+    print(f"Job submitted: {job_id}")
+    if job_url:
+        print(f"  Job page:   {job_url}")
+    print(f"  Model repo: https://huggingface.co/{repo_id}")
+    print(f"  Monitor:    hf jobs logs {job_id}")
+    print(f"  Cancel:     hf jobs cancel {job_id}")
+
+    if cfg.job.detach:
+        return
+
+    done = threading.Event()
+    detached = threading.Event()
+    pushed_ok = threading.Event()
+    stage_holder: dict[str, str | None] = {}
+
+    def _poll() -> None:
+        stage_holder["stage"] = _poll_until_done(job_id, done, status_holder=stage_holder)
+
+    poll_thread = threading.Thread(target=_poll, daemon=True)
+    poll_thread.start()
+    # Finish as soon as the model is pushed, rather than waiting out the platform's
+    # post-run finalization before the job stage flips to COMPLETED. This matches the
+    # exact log line emitted by PreTrainedPolicy.push_model_to_hub — the two must stay
+    # in sync. If it ever stops matching we just fall back to stage-based completion
+    # (~30s slower), so the contract is an optimization, not a correctness requirement.
+    success_marker = f"Model pushed to https://huggingface.co/{repo_id}"
+    log_thread = threading.Thread(
+        target=_tail_logs, args=(job_id, done, success_marker, pushed_ok), daemon=True
+    )
+    log_thread.start()
+
+    def _detach(sig, frame):
+        detached.set()
+        done.set()
+        print("\nDetached. Job is still running.")
+        print(f"  Monitor: hf jobs logs {job_id}")
+        print(f"  Cancel:  hf jobs cancel {job_id}")
+
+    # signal.signal only works on the main thread; when called from a worker thread
+    # (e.g. an orchestration framework) skip the Ctrl-C-detaches-instead-of-cancels
+    # handler rather than crashing with ValueError.
+    install_sigint = threading.current_thread() is threading.main_thread()
+    original_sigint = signal.getsignal(signal.SIGINT) if install_sigint else None
+    if install_sigint:
+        signal.signal(signal.SIGINT, _detach)
+    try:
+        # Timeout-based join so SIGINT is delivered to the main thread promptly.
+        while poll_thread.is_alive():
+            poll_thread.join(timeout=0.5)
+        log_thread.join(timeout=5)
+    finally:
+        if install_sigint:
+            signal.signal(signal.SIGINT, original_sigint)
+
+    if detached.is_set():
+        return
+
+    if pushed_ok.is_set():
+        print(f"\nTraining complete — model pushed to https://huggingface.co/{repo_id}")
+        return
+
+    stage = stage_holder.get("stage")
+    if stage != "COMPLETED":
+        message = stage_holder.get("message")
+        detail = f" ({message})" if message else ""
+        raise RuntimeError(
+            f"Job {job_id} ended with stage={stage}{detail}. Check logs: hf jobs logs {job_id}"
+        )

src/lerobot/policies/__init__.py

@@ -18,6 +18,7 @@ from .act.configuration_act import ACTConfig as ACTConfig
 from .diffusion.configuration_diffusion import DiffusionConfig as DiffusionConfig
 from .eo1.configuration_eo1 import EO1Config as EO1Config
 from .factory import get_policy_class, make_policy, make_policy_config, make_pre_post_processors
+from .fastwam.configuration_fastwam import FastWAMConfig as FastWAMConfig
 from .gaussian_actor.configuration_gaussian_actor import GaussianActorConfig as GaussianActorConfig
 from .groot.configuration_groot import GrootConfig as GrootConfig
 from .molmoact2.configuration_molmoact2 import MolmoAct2Config as MolmoAct2Config
@@ -42,6 +43,7 @@ __all__ = [
     "ACTConfig",
     "DiffusionConfig",
     "EO1Config",
+    "FastWAMConfig",
     "GaussianActorConfig",
     "GrootConfig",
     "MolmoAct2Config",

src/lerobot/policies/factory.py

@@ -47,6 +47,7 @@ from lerobot.utils.feature_utils import dataset_to_policy_features
 from .act.configuration_act import ACTConfig
 from .diffusion.configuration_diffusion import DiffusionConfig
 from .eo1.configuration_eo1 import EO1Config
+from .fastwam.configuration_fastwam import FastWAMConfig
 from .gaussian_actor.configuration_gaussian_actor import GaussianActorConfig
 from .groot.configuration_groot import GrootConfig
 from .molmoact2.configuration_molmoact2 import MolmoAct2Config
@@ -162,6 +163,10 @@ def get_policy_class(name: str) -> type[PreTrainedPolicy]:
         from .vla_jepa.modeling_vla_jepa import VLAJEPAPolicy
 
         return VLAJEPAPolicy
+    elif name == "fastwam":
+        from .fastwam.modeling_fastwam import FastWAMPolicy
+
+        return FastWAMPolicy
     else:
         try:
             return _get_policy_cls_from_policy_name(name=name)
@@ -218,6 +223,8 @@ def make_policy_config(policy_type: str, **kwargs) -> PreTrainedConfig:
         return MolmoAct2Config(**kwargs)
     elif policy_type == "vla_jepa":
         return VLAJEPAConfig(**kwargs)
+    elif policy_type == "fastwam":
+        return FastWAMConfig(**kwargs)
     else:
         try:
             config_cls = PreTrainedConfig.get_choice_class(policy_type)
@@ -451,6 +458,14 @@ def make_pre_post_processors(
             dataset_stats=kwargs.get("dataset_stats"),
         )
 
+    elif isinstance(policy_cfg, FastWAMConfig):
+        from .fastwam.processor_fastwam import make_fastwam_pre_post_processors
+
+        processors = make_fastwam_pre_post_processors(
+            config=policy_cfg,
+            dataset_stats=kwargs.get("dataset_stats"),
+        )
+
     else:
         try:
             processors = _make_processors_from_policy_config(

src/lerobot/policies/fastwam/README.md

@@ -0,0 +1 @@
+../../../../docs/source/policy_fastwam_README.md

src/lerobot/policies/fastwam/__init__.py

@@ -0,0 +1,23 @@
+# Copyright 2024 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from .configuration_fastwam import FastWAMConfig
+from .modeling_fastwam import FastWAMPolicy
+from .processor_fastwam import make_fastwam_pre_post_processors
+
+__all__ = [
+    "FastWAMConfig",
+    "FastWAMPolicy",
+    "make_fastwam_pre_post_processors",
+]

src/lerobot/policies/fastwam/configuration_fastwam.py

@@ -0,0 +1,399 @@
+# Copyright 2024 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from pathlib import Path
+from typing import Any
+
+from lerobot.configs import (
+    FeatureType,
+    NormalizationMode,
+    PolicyFeature,
+    PreTrainedConfig,
+)
+from lerobot.optim import AdamWConfig
+from lerobot.utils.constants import ACTION, OBS_STATE
+
+WAN22_MODEL_ID = "Wan-AI/Wan2.2-TI2V-5B"
+WAN22_DIFFUSERS_MODEL_ID = "Wan-AI/Wan2.2-TI2V-5B-Diffusers"
+FASTWAM_BASE_MODEL_ID = "lerobot/fastwam_base"
+WAN_T5_TOKENIZER_ID = "google/umt5-xxl"
+
+
+_FASTWAM_VIDEO_BASE_COMPAT_KEYS = (
+    "patch_size",
+    "in_dim",
+    "hidden_dim",
+    "ffn_dim",
+    "freq_dim",
+    "text_dim",
+    "out_dim",
+    "num_heads",
+    "attn_head_dim",
+    "num_layers",
+)
+
+_FASTWAM_ACTION_BASE_COMPAT_KEYS = (
+    "hidden_dim",
+    "ffn_dim",
+    "num_heads",
+    "attn_head_dim",
+    "num_layers",
+    "text_dim",
+    "freq_dim",
+)
+
+
+def default_video_dit_config(action_dim: int) -> dict[str, Any]:
+    return {
+        "patch_size": [1, 2, 2],
+        "in_dim": 48,
+        "hidden_dim": 3072,
+        "ffn_dim": 14336,
+        "freq_dim": 256,
+        "text_dim": 4096,
+        "out_dim": 48,
+        "num_heads": 24,
+        "attn_head_dim": 128,
+        "num_layers": 30,
+        "eps": 1.0e-6,
+        "seperated_timestep": True,
+        "use_gradient_checkpointing": False,
+        "video_attention_mask_mode": "first_frame_causal",
+        "action_conditioned": False,
+        "action_dim": action_dim,
+        "action_group_causal_mask_mode": "group_diagonal",
+        "fp32_attention": True,
+    }
+
+
+def default_action_dit_config(action_dim: int) -> dict[str, Any]:
+    return {
+        "action_dim": action_dim,
+        "hidden_dim": 1024,
+        "ffn_dim": 4096,
+        "num_heads": 24,
+        "attn_head_dim": 128,
+        "num_layers": 30,
+        "text_dim": 4096,
+        "freq_dim": 256,
+        "eps": 1.0e-6,
+        "use_gradient_checkpointing": False,
+        "fp32_attention": True,
+    }
+
+
+def _coerce_enum(enum_cls: type, value: Any) -> Any:
+    if isinstance(value, enum_cls):
+        return value
+    try:
+        return enum_cls(value)
+    except (TypeError, ValueError) as exc:
+        member = getattr(enum_cls, str(value), None)
+        if member is None:
+            raise ValueError(f"Cannot coerce {value!r} into {enum_cls.__name__}.") from exc
+        return member
+
+
+def _coerce_policy_features(features: dict[str, Any] | None) -> dict[str, PolicyFeature] | None:
+    if features is None:
+        return None
+    coerced = {}
+    for name, feature in features.items():
+        if isinstance(feature, PolicyFeature):
+            coerced[name] = feature
+            continue
+        coerced[name] = PolicyFeature(
+            type=_coerce_enum(FeatureType, feature["type"]),
+            shape=tuple(feature["shape"]),
+        )
+    return coerced
+
+
+def _is_local_model_id(value: str) -> bool:
+    path = Path(value).expanduser()
+    return path.is_absolute() or value.startswith(("./", "../", "~")) or path.exists()
+
+
+def _validate_wan_model_id(value: str, field_name: str) -> str:
+    if value == WAN22_MODEL_ID or _is_local_model_id(value):
+        return value
+    raise ValueError(f"`{field_name}` must be `{WAN22_MODEL_ID}` or an explicit local path, got `{value}`.")
+
+
+def is_fastwam_base_compatible_config(config: FastWAMConfig) -> bool:
+    """Return whether `fastwam_base` partial weights can initialize this config."""
+
+    default_video_config = default_video_dit_config(config.action_dim)
+    default_action_config = default_action_dit_config(config.action_dim)
+    return all(
+        config.video_dit_config.get(key) == default_video_config.get(key)
+        for key in _FASTWAM_VIDEO_BASE_COMPAT_KEYS
+    ) and all(
+        config.action_dit_config.get(key) == default_action_config.get(key)
+        for key in _FASTWAM_ACTION_BASE_COMPAT_KEYS
+    )
+
+
+@PreTrainedConfig.register_subclass("fastwam")
+@dataclass
+class FastWAMConfig(PreTrainedConfig):
+    """Configuration for the FastWAM LeRobot policy.
+
+    Args:
+        action_dim (int): Number of scalar action channels per timestep.
+        proprio_dim (int | None): Number of proprioception channels used as an
+            extra text-context token. `None` disables proprio conditioning.
+        action_horizon (int): Number of actions predicted by one policy call.
+        num_video_frames (int): Raw video sampling window (in dataset frames). The
+            model actually operates on `model_video_frames` frames after subsampling
+            by `action_video_freq_ratio`.
+        action_video_freq_ratio (int): Actions are sampled at this multiple of the
+            video frame rate. Video frames are taken every `action_video_freq_ratio`-th
+            raw frame, so the model sees `(num_video_frames - 1) // ratio + 1` frames
+            spanning the same time window as `action_horizon` actions (ratio actions
+            per video frame).
+        image_size (tuple[int, int]): Concatenated image size as `(height, width)`.
+        context_len (int): Maximum text embedding token length.
+        video_dit_config (dict[str, Any] | None): Wan video expert config.
+        action_dit_config (dict[str, Any] | None): Action expert config.
+        use_gradient_checkpointing (bool): Enable activation checkpointing in both DiT
+            experts (trades compute for memory; propagated into the DiT configs).
+        freeze_video_expert (bool): Freeze the ~5B Wan video expert
+            (`model.video_expert`) so only the action expert + proprio encoder train.
+            Cuts the AdamW optimizer footprint substantially; the video expert keeps its
+            pretrained weights. (If enabled, also set `loss.lambda_video=0` to skip the
+            now-gradient-free video loss compute.)
+    """
+
+    n_obs_steps: int = 1
+    action_dim: int = 7
+    proprio_dim: int | None = 8
+    action_horizon: int = 32
+    n_action_steps: int = 32
+    num_video_frames: int = 33
+    action_video_freq_ratio: int = 4
+    image_size: tuple[int, int] = (224, 448)
+    context_len: int = 128
+    model_id: str = WAN22_MODEL_ID
+    tokenizer_model_id: str = WAN_T5_TOKENIZER_ID
+    text_encoder_model_id: str = WAN22_DIFFUSERS_MODEL_ID
+    base_model_id: str | None = FASTWAM_BASE_MODEL_ID
+    tokenizer_max_len: int = 128
+    load_text_encoder: bool = True
+    mot_checkpoint_mixed_attn: bool = False
+    torch_dtype: str = "bfloat16"
+    prompt_template: str = (
+        "A video recorded from a robot's point of view executing the following instruction: {task}"
+    )
+    num_inference_steps: int = 10
+    inference_seed: int | None = 42
+    rand_device: str = "cpu"
+    text_cfg_scale: float = 1.0
+    negative_prompt: str = ""
+    sigma_shift: float | None = None
+    tiled: bool = False
+    fp32_attention: bool = True
+    use_gradient_checkpointing: bool = False
+    freeze_video_expert: bool = False
+    toggle_action_dimensions: list[int] = field(default_factory=list)
+    video_scheduler: dict[str, float | int] = field(
+        default_factory=lambda: {"train_shift": 5.0, "infer_shift": 5.0, "num_train_timesteps": 1000}
+    )
+    action_scheduler: dict[str, float | int] = field(
+        default_factory=lambda: {"train_shift": 5.0, "infer_shift": 5.0, "num_train_timesteps": 1000}
+    )
+    loss: dict[str, float] = field(default_factory=lambda: {"lambda_video": 1.0, "lambda_action": 1.0})
+    video_dit_config: dict[str, Any] | None = None
+    action_dit_config: dict[str, Any] | None = None
+    normalization_mapping: dict[str, NormalizationMode] = field(
+        default_factory=lambda: {
+            "VISUAL": NormalizationMode.IDENTITY,
+            "STATE": NormalizationMode.MEAN_STD,
+            "ACTION": NormalizationMode.MEAN_STD,
+        }
+    )
+    input_features: dict[str, PolicyFeature] | None = None
+    output_features: dict[str, PolicyFeature] | None = None
+    optimizer_lr: float = 1.0e-4
+    optimizer_weight_decay: float = 1.0e-2
+
+    def __post_init__(self) -> None:
+        super().__post_init__()
+        self.image_size = tuple(self.image_size)
+        self.model_id = _validate_wan_model_id(self.model_id, "model_id")
+        self.input_features = _coerce_policy_features(self.input_features)
+        self.output_features = _coerce_policy_features(self.output_features)
+        self.toggle_action_dimensions = [int(dim) for dim in self.toggle_action_dimensions]
+        self.video_dit_config = self.video_dit_config or default_video_dit_config(self.action_dim)
+        self.action_dit_config = self.action_dit_config or default_action_dit_config(self.action_dim)
+        self.video_dit_config["fp32_attention"] = bool(self.fp32_attention)
+        self.action_dit_config["fp32_attention"] = bool(self.fp32_attention)
+        self.video_dit_config["use_gradient_checkpointing"] = bool(self.use_gradient_checkpointing)
+        self.action_dit_config["use_gradient_checkpointing"] = bool(self.use_gradient_checkpointing)
+        if self.input_features is None:
+            height, width = self.image_size
+            self.input_features = {
+                "observation.images.image": PolicyFeature(
+                    type=FeatureType.VISUAL,
+                    shape=(3, height, width),
+                )
+            }
+            if self.proprio_dim is not None:
+                self.input_features[OBS_STATE] = PolicyFeature(
+                    type=FeatureType.STATE,
+                    shape=(self.proprio_dim,),
+                )
+        if self.output_features is None:
+            self.output_features = {ACTION: PolicyFeature(type=FeatureType.ACTION, shape=(self.action_dim,))}
+        self.validate_features()
+        if self.pretrained_path or self.use_peft or not self.base_model_id:
+            return
+        if not is_fastwam_base_compatible_config(self):
+            return
+        self.pretrained_path = Path(self.base_model_id)
+        self._auto_pretrained_path = True
+
+    def _save_pretrained(self, save_directory: Path) -> None:
+        if not getattr(self, "_auto_pretrained_path", False):
+            super()._save_pretrained(save_directory)
+            return
+
+        pretrained_path = self.pretrained_path
+        self.pretrained_path = None
+        try:
+            super()._save_pretrained(save_directory)
+        finally:
+            self.pretrained_path = pretrained_path
+
+    def get_optimizer_preset(self) -> AdamWConfig:
+        return AdamWConfig(lr=self.optimizer_lr, weight_decay=self.optimizer_weight_decay)
+
+    def get_scheduler_preset(self) -> None:
+        return None
+
+    def set_dataset_feature_metadata(self, dataset_features: dict[str, Any]) -> None:
+        """Rebuild visual input features from the dataset's real camera keys.
+
+        FastWAM's `__post_init__` installs a synthetic single-image default
+        (`observation.images.image` at full `image_size` width). For datasets
+        with one or more separately-named cameras (e.g. `observation.images.top`,
+        `observation.images.wrist`), this hook — invoked by `make_policy` once the
+        dataset metadata is known — replaces that default with the actual camera
+        keys, each declared at the policy's native per-camera resolution
+        (`image_size[0]` x `image_size[1] // num_cameras`). The accompanying
+        resize step in `make_fastwam_pre_post_processors` resizes raw frames to
+        match, so heterogeneous source resolutions (e.g. 480x640) are supported.
+        """
+        image_keys = sorted(
+            key
+            for key, feature in dataset_features.items()
+            if key.startswith("observation.images.") and feature.get("dtype") in ("video", "image")
+        )
+        if not image_keys:
+            return
+        height, total_width = self.image_size
+        per_cam_width = total_width // len(image_keys)
+        new_inputs: dict[str, PolicyFeature] = {
+            key: PolicyFeature(type=FeatureType.VISUAL, shape=(3, height, per_cam_width))
+            for key in image_keys
+        }
+        if self.proprio_dim is not None and OBS_STATE in dataset_features:
+            new_inputs[OBS_STATE] = PolicyFeature(type=FeatureType.STATE, shape=(self.proprio_dim,))
+        self.input_features = new_inputs
+        self.validate_features()
+
+    def validate_features(self) -> None:
+        if self.action_dim <= 0:
+            raise ValueError(f"`action_dim` must be positive, got {self.action_dim}.")
+        if self.action_horizon <= 0:
+            raise ValueError(f"`action_horizon` must be positive, got {self.action_horizon}.")
+        if self.n_action_steps > self.action_horizon:
+            raise ValueError("`n_action_steps` cannot exceed `action_horizon`.")
+        if self.action_video_freq_ratio <= 0:
+            raise ValueError(
+                f"`action_video_freq_ratio` must be positive, got {self.action_video_freq_ratio}."
+            )
+        # Video frames are subsampled by action_video_freq_ratio; the resulting model frame
+        # count must satisfy T % 4 == 1 for the VAE temporal tokenization (mirrors the
+        # original FastWAM dataset asserts).
+        if (self.num_video_frames - 1) % self.action_video_freq_ratio != 0:
+            raise ValueError(
+                f"`num_video_frames - 1` ({self.num_video_frames - 1}) must be divisible by "
+                f"`action_video_freq_ratio` ({self.action_video_freq_ratio})."
+            )
+        if ((self.num_video_frames - 1) // self.action_video_freq_ratio) % 4 != 0:
+            raise ValueError(
+                f"Subsampled video transitions ({(self.num_video_frames - 1) // self.action_video_freq_ratio}) "
+                "must be divisible by 4 for VAE tokenization (i.e. model_video_frames % 4 == 1)."
+            )
+        if self.action_horizon % ((self.num_video_frames - 1) // self.action_video_freq_ratio) != 0:
+            raise ValueError(
+                f"`action_horizon` ({self.action_horizon}) must be divisible by the number of "
+                f"video transitions ({(self.num_video_frames - 1) // self.action_video_freq_ratio})."
+            )
+        if not self.image_features:
+            raise ValueError("FastWAM requires at least one image feature.")
+        if self.action_feature is None:
+            raise ValueError("FastWAM requires `action` in output_features.")
+        action_shape = tuple(self.action_feature.shape)
+        if action_shape != (self.action_dim,):
+            raise ValueError(
+                f"FastWAM action feature shape must be ({self.action_dim},), got {action_shape}."
+            )
+        if self.proprio_dim is not None:
+            state_feature = self.robot_state_feature
+            if state_feature is None:
+                raise ValueError("FastWAM requires `observation.state` when `proprio_dim` is set.")
+            state_shape = tuple(state_feature.shape)
+            if state_shape != (self.proprio_dim,):
+                raise ValueError(
+                    f"FastWAM state feature shape must be ({self.proprio_dim},), got {state_shape}."
+                )
+        height, width = self.image_size
+        image_width_sum = 0
+        for name, feature in self.image_features.items():
+            shape = tuple(feature.shape)
+            if len(shape) != 3 or shape[0] != 3:
+                raise ValueError(f"FastWAM image feature `{name}` must have shape (3, H, W), got {shape}.")
+            if shape[1] != height:
+                raise ValueError(f"FastWAM image feature `{name}` height must be {height}, got {shape[1]}.")
+            image_width_sum += shape[2]
+        if image_width_sum != width:
+            raise ValueError(f"FastWAM image feature widths must sum to {width}, got {image_width_sum}.")
+
+    @property
+    def model_video_frames(self) -> int:
+        """Number of video frames the model actually operates on, after subsampling the
+        raw `num_video_frames` window by `action_video_freq_ratio` (e.g. 33 -> 9)."""
+        return (self.num_video_frames - 1) // self.action_video_freq_ratio + 1
+
+    @property
+    def observation_delta_indices(self) -> list[int]:
+        # Load the video frames the model is supervised on: the future window subsampled by
+        # action_video_freq_ratio (e.g. [0, 4, 8, ..., 32] -> 9 frames). Each video frame is
+        # thus `action_video_freq_ratio` actions apart, while actions load at the full rate
+        # (`action_delta_indices` = range(action_horizon)). Returning None would load only the
+        # current frame, making the video target a static repeat (degenerate supervision).
+        return list(range(0, self.num_video_frames, self.action_video_freq_ratio))
+
+    @property
+    def action_delta_indices(self) -> list[int]:
+        return list(range(self.action_horizon))
+
+    @property
+    def reward_delta_indices(self) -> None:
+        return None

src/lerobot/policies/fastwam/modeling_fastwam.py

@@ -0,0 +1,440 @@
+# Copyright 2024 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+import logging
+from collections import deque
+from typing import Any
+
+import torch
+from torch import Tensor
+
+from lerobot.policies.pretrained import PreTrainedPolicy
+from lerobot.utils.constants import OBS_STATE
+from lerobot.utils.import_utils import require_package
+
+from .configuration_fastwam import FastWAMConfig
+from .wan import (
+    ActionDiT,
+    FastWAM,
+    MoT,
+    WanVideoDiT,
+    build_wan_tokenizer,
+    load_pretrained_wan_text_encoder,
+    load_pretrained_wan_vae,
+)
+
+
+class FastWAMPolicy(PreTrainedPolicy):
+    """LeRobot policy wrapper for FastWAM.
+
+    Attention backend: FastWAM's DiT uses ``torch.nn.functional.scaled_dot_product_attention``
+    (SDPA) for all attention. It does not use FlashAttention, because MoT routing requires
+    arbitrary boolean ``[query, key]`` masks that the FlashAttention varlen API cannot express;
+    installing ``flash-attn`` has no effect on the FastWAM path. (SDPA may still dispatch to
+    PyTorch's own flash/mem-efficient/math kernel internally, unrelated to the ``flash-attn`` package.)
+
+    Args:
+        config (FastWAMConfig): FastWAM policy configuration.
+        dataset_stats (dict[str, dict[str, Tensor]] | None): Optional LeRobot
+            dataset statistics passed by the training/evaluation stack.
+    """
+
+    config_class = FastWAMConfig
+    name = "fastwam"
+
+    def __init__(
+        self,
+        config: FastWAMConfig,
+        dataset_stats: dict[str, dict[str, Tensor]] | None = None,
+        **kwargs: Any,
+    ):
+        # FastWAM's Wan2.2 backbone needs transformers (UMT5 text encoder/tokenizer) and
+        # diffusers (Wan VAE), both behind the `fastwam` extra. Fail fast with an actionable
+        # message in base installs rather than deep in Wan component construction.
+        require_package("transformers", extra="fastwam")
+        require_package("diffusers", extra="fastwam")
+        # `make_policy`/`from_pretrained` forward extra kwargs (e.g. `dataset_meta`); the
+        # dataset feature metadata is already applied to `config` by make_policy upstream,
+        # so we accept and ignore them, matching the other LeRobot policies.
+        super().__init__(config, dataset_stats)
+        config.validate_features()
+        self.config = config
+        self.dataset_stats = dataset_stats
+        self.model = self._build_core_model(config)
+        if config.freeze_video_expert and getattr(self.model, "video_expert", None) is not None:
+            # Freeze the ~5B Wan video expert; get_optim_params filters on requires_grad,
+            # so its params drop out of the optimizer (and DDP skips them).
+            self.model.video_expert.requires_grad_(False)
+            # The transformer blocks are re-parented onto the MoTLayers (single FSDP owner), so
+            # `video_expert.requires_grad_` no longer reaches them — freeze them via the layers.
+            mot = getattr(self.model, "mot", None)
+            if mot is not None and getattr(mot, "layers", None) is not None:
+                for layer in mot.layers:
+                    if "video" in layer.blocks:
+                        layer.blocks["video"].requires_grad_(False)
+        self.reset()
+
+    @classmethod
+    def _load_as_safetensor(cls, model, model_file: str, map_location: str, strict: bool):
+        """Shape-aware load that supports cross-embodiment fine-tuning.
+
+        `safetensors.load_model(strict=False)` ignores missing/unexpected keys but
+        still raises on a shape mismatch for a shared key. When fine-tuning from a
+        checkpoint trained on a different embodiment (e.g. the LIBERO 7-DoF / 8-dim
+        checkpoint adapted to a 6-DoF / 6-dim arm), the action encoder/head and
+        proprio encoder legitimately differ in shape. With `strict=False` we drop
+        only those shape-mismatched tensors — leaving them at their freshly
+        initialized values — and load every compatible tensor. With `strict=True`
+        the standard exact-match loader is used.
+        """
+        from safetensors import safe_open
+
+        model_state_dict = model.state_dict()
+        mismatched = []
+        with safe_open(model_file, framework="pt") as f:
+            checkpoint_keys = list(f.keys())
+            for key in checkpoint_keys:
+                if key in model_state_dict and tuple(model_state_dict[key].shape) != tuple(
+                    f.get_slice(key).get_shape()
+                ):
+                    mismatched.append(key)
+
+        if not mismatched:
+            return super()._load_as_safetensor(model, model_file, map_location, strict)
+        if strict:
+            raise RuntimeError(
+                f"FastWAM: {len(mismatched)} checkpoint tensors have a shape mismatch under "
+                f"strict=True: {mismatched}"
+            )
+
+        from safetensors.torch import load_file
+
+        logging.warning(
+            "FastWAM cross-embodiment load: reinitializing %d shape-mismatched tensor(s), keeping "
+            "every compatible weight: %s",
+            len(mismatched),
+            mismatched,
+        )
+        state_dict = load_file(model_file, device="cpu")
+        for key in mismatched:
+            state_dict.pop(key, None)
+        model.load_state_dict(state_dict, strict=False)
+        if map_location and map_location != "cpu":
+            model.to(map_location)
+        return model
+
+    def get_optim_params(self) -> list[Tensor]:
+        # Return the trainable tensors directly (a single param group). The optimizer
+        # builder wraps these in a param group; returning a bare {"params": [...]} dict
+        # instead would make `list(...)` yield the key string "params".
+        params = (
+            list(self.model.dit.parameters()) if hasattr(self.model, "dit") else list(self.model.parameters())
+        )
+        proprio_encoder = getattr(self.model, "proprio_encoder", None)
+        if proprio_encoder is not None:
+            params.extend(list(proprio_encoder.parameters()))
+        return [p for p in params if p.requires_grad]
+
+    def reset(self) -> None:
+        self._action_queue: deque[Tensor] = deque([], maxlen=self.config.n_action_steps)
+
+    def _batch_to_training_sample(self, batch: dict[str, Tensor]) -> dict[str, Tensor]:
+        """Adapt a standard LeRobot batch to the FastWAM-native sample that
+        `FastWAM.build_inputs` consumes (`video`, `action`, `context`/`context_mask`,
+        per-frame `proprio`).
+
+        The LeRobot training loop passes raw `observation.images.*`, a single-step
+        `observation.state` `[B, D]`, `action`, and a language `task` string. We do
+        only the translation `build_inputs` can't: stack the camera frames into a
+        video, encode the prompt with the (frozen) text encoder (mirroring inference,
+        so language-conditioned datasets need no precomputed context), and give proprio
+        the per-frame axis `build_inputs` indexes. All shape/presence validation is
+        left to `build_inputs`, the single authority on the contract.
+        """
+        sample = dict(batch)
+        if "video" not in sample:
+            sample["video"] = _stack_video_from_images(batch, self.config)
+        if "context" not in sample or "context_mask" not in sample:
+            prompt = _prompt_from_batch(batch=batch, config=self.config)
+            if prompt is None:
+                raise KeyError(
+                    "FastWAM training requires a `task`/`prompt` to encode text context, "
+                    "or precomputed `context`/`context_mask` in the batch."
+                )
+            sample["context"], sample["context_mask"] = self.model.encode_prompt(prompt)
+        if self.config.proprio_dim is not None and "proprio" not in sample:
+            state = sample.get(OBS_STATE)
+            if state is not None:
+                # LeRobot gives a single-step state [B, D]; build_inputs expects
+                # per-frame [B, T, D] and uses frame 0, so add a T=1 axis.
+                sample["proprio"] = state.unsqueeze(1) if state.ndim == 2 else state
+        return sample
+
+    def forward(self, batch: dict[str, Tensor]) -> tuple[Tensor, dict[str, Any]]:
+        """Compute FastWAM training loss for a LeRobot batch.
+
+        Args:
+            batch (dict[str, Tensor]): Batch containing FastWAM-ready keys
+                (`video`, `action`, `context`, `context_mask`) or LeRobot keys
+                that can be adapted (`observation.images.*`, `observation.state`,
+                `action`, `action_is_pad`).
+
+        Returns:
+            tuple[Tensor, dict[str, Any]]: The scalar loss to backprop, and a dict of
+            logging metrics (e.g. `loss_video`, `loss_action`) — the `(loss, output_dict)`
+            contract the LeRobot training loop expects.
+        """
+
+        sample = self._batch_to_training_sample(batch)
+        loss, metrics = self.model.training_loss(sample)
+        return loss, dict(metrics or {})
+
+    @torch.no_grad()
+    def predict_action_chunk(self, batch: dict[str, Tensor], **_: Any) -> Tensor:
+        """Predict a chunk of actions from the current FastWAM observation.
+
+        Args:
+            batch (dict[str, Tensor]): Inference batch with `input_image` or
+                image observation keys, plus `context/context_mask` or `prompt`.
+
+        Returns:
+            Tensor: Action chunk with shape `[B, action_horizon, action_dim]`.
+        """
+
+        self.eval()
+        infer_kwargs = _batch_to_infer_kwargs(batch=batch, config=self.config)
+        batch_size = _infer_kwargs_batch_size(infer_kwargs)
+        if batch_size == 1:
+            action = _action_from_model_output(self.model.infer_action(**infer_kwargs))
+        else:
+            action = torch.cat(
+                [
+                    _action_from_model_output(
+                        self.model.infer_action(
+                            **_slice_infer_kwargs(infer_kwargs, index=i, batch_size=batch_size)
+                        )
+                    )
+                    for i in range(batch_size)
+                ],
+                dim=0,
+            )
+        return action.to(device=batch_device(batch), dtype=torch.float32)
+
+    @torch.no_grad()
+    def select_action(self, batch: dict[str, Tensor], **kwargs: Any) -> Tensor:
+        self.eval()
+        if len(self._action_queue) == 0:
+            actions = self.predict_action_chunk(batch, **kwargs)[:, : self.config.n_action_steps]
+            self._action_queue.extend(actions.transpose(0, 1))
+        return self._action_queue.popleft()
+
+    def _build_core_model(self, config: FastWAMConfig) -> FastWAM:
+        """Build the FastWAM core for training / inference.
+
+        Only the trainable parts (the MoT DiT and the proprio encoder) are
+        materialized empty here and then filled from the policy's
+        `model.safetensors` by the base `from_pretrained`. The *frozen* Wan2.2 VAE
+        and UMT5 text encoder are loaded with their real weights from the
+        `Wan-AI/Wan2.2-TI2V-5B-Diffusers` repo (cached in the HF cache, shared
+        across checkpoints) and are intentionally excluded from `model.safetensors`
+        — see `FastWAM.__init__`. The tokenizer comes from `google/umt5-xxl`.
+        """
+        dtype = _dtype_from_name(config.torch_dtype)
+        device = config.device
+        video_expert = WanVideoDiT(**config.video_dit_config).to(device=device, dtype=dtype)
+        action_expert = ActionDiT(**config.action_dit_config).to(device=device, dtype=dtype)
+        mot = MoT(
+            mixtures={"video": video_expert, "action": action_expert},
+            mot_checkpoint_mixed_attn=config.mot_checkpoint_mixed_attn,
+        )
+        text_encoder = (
+            load_pretrained_wan_text_encoder(
+                model_id=config.text_encoder_model_id, torch_dtype=dtype, device=device
+            )
+            if config.load_text_encoder
+            else None
+        )
+        return FastWAM(
+            video_expert=video_expert,
+            action_expert=action_expert,
+            mot=mot,
+            vae=load_pretrained_wan_vae(torch_dtype=dtype, device=device),
+            text_encoder=text_encoder,
+            tokenizer=build_wan_tokenizer(
+                model_id=config.tokenizer_model_id, tokenizer_max_len=config.tokenizer_max_len
+            ),
+            text_dim=int(config.video_dit_config["text_dim"]),
+            proprio_dim=config.proprio_dim,
+            device=device,
+            torch_dtype=dtype,
+            video_train_shift=float(config.video_scheduler["train_shift"]),
+            video_infer_shift=float(config.video_scheduler["infer_shift"]),
+            video_num_train_timesteps=int(config.video_scheduler["num_train_timesteps"]),
+            action_train_shift=float(config.action_scheduler["train_shift"]),
+            action_infer_shift=float(config.action_scheduler["infer_shift"]),
+            action_num_train_timesteps=int(config.action_scheduler["num_train_timesteps"]),
+            loss_lambda_video=float(config.loss["lambda_video"]),
+            loss_lambda_action=float(config.loss["lambda_action"]),
+        )
+
+
+def _scalar(value: Any) -> Any:
+    """Unwrap a 0-/1-element tensor (e.g. from DataLoader collation) to a Python scalar."""
+    return value.item() if isinstance(value, Tensor) else value
+
+
+def _batch_to_infer_kwargs(batch: dict[str, Tensor], config: FastWAMConfig) -> dict[str, Any]:
+    return {
+        "prompt": _prompt_from_batch(batch=batch, config=config),
+        "input_image": _input_image_from_batch(batch, config),
+        "action_horizon": config.action_horizon,
+        "proprio": batch.get("proprio", batch.get(OBS_STATE)),
+        "context": batch.get("context"),
+        "context_mask": batch.get("context_mask"),
+        "negative_prompt": batch.get("negative_prompt", config.negative_prompt),
+        "text_cfg_scale": float(_scalar(batch.get("text_cfg_scale", config.text_cfg_scale))),
+        "num_inference_steps": int(_scalar(batch.get("num_inference_steps", config.num_inference_steps))),
+        "sigma_shift": batch.get("sigma_shift", config.sigma_shift),
+        "seed": batch.get("seed", config.inference_seed),
+        "rand_device": batch.get("rand_device", config.rand_device),
+        "tiled": bool(batch.get("tiled", config.tiled)),
+    }
+
+
+def _prompt_from_batch(batch: dict[str, Tensor], config: FastWAMConfig) -> Any:
+    prompt = batch.get("prompt")
+    if prompt is not None:
+        return prompt
+
+    task = batch.get("task")
+    if task is None:
+        return None
+    if isinstance(task, str):
+        return config.prompt_template.format(task=task)
+    if isinstance(task, (list, tuple)):
+        return [config.prompt_template.format(task=str(item)) for item in task]
+    return config.prompt_template.format(task=str(task))
+
+
+def _action_from_model_output(output: Any) -> Tensor:
+    action = output["action"] if isinstance(output, dict) else output
+    if action.ndim == 2:
+        action = action.unsqueeze(0)
+    return action
+
+
+def _infer_kwargs_batch_size(infer_kwargs: dict[str, Any]) -> int:
+    image = infer_kwargs["input_image"]
+    if not isinstance(image, Tensor):
+        raise TypeError(f"`input_image` must be a tensor, got {type(image).__name__}.")
+    if image.ndim == 3:
+        return 1
+    if image.ndim == 4:
+        return int(image.shape[0])
+    raise ValueError(f"`input_image` must be [B,C,H,W] or [C,H,W], got {tuple(image.shape)}.")
+
+
+def _slice_infer_kwargs(infer_kwargs: dict[str, Any], *, index: int, batch_size: int) -> dict[str, Any]:
+    return {
+        key: _slice_infer_value(value, index=index, batch_size=batch_size)
+        for key, value in infer_kwargs.items()
+    }
+
+
+def _slice_infer_value(value: Any, *, index: int, batch_size: int) -> Any:
+    if isinstance(value, Tensor) and value.ndim > 0 and value.shape[0] == batch_size:
+        return value[index : index + 1]
+    if isinstance(value, (list, tuple)) and len(value) == batch_size:
+        return value[index]
+    return value
+
+
+def _dtype_from_name(name: str) -> torch.dtype:
+    dtype_map = {"float32": torch.float32, "float16": torch.float16, "bfloat16": torch.bfloat16}
+    if name not in dtype_map:
+        raise ValueError(f"Unsupported torch dtype `{name}`.")
+    return dtype_map[name]
+
+
+def batch_device(batch: dict[str, Any]) -> torch.device:
+    for value in batch.values():
+        if isinstance(value, Tensor):
+            return value.device
+    return torch.device("cpu")
+
+
+def _resize_frames(frames: Tensor, size: tuple[int, int]) -> Tensor:
+    """Resize a frame tensor to `size` (H, W), tolerating a leading temporal/batch stack.
+
+    `interpolate` only accepts a single leading batch dim (`[N, C, H, W]`), but FastWAM camera
+    tensors arrive as `[B, C, H, W]` (live eval) or `[B, T, C, H, W]` (temporal stack), so flatten
+    any leading dims into the batch, resize, then restore. A no-op when already at `size`.
+    """
+    if tuple(frames.shape[-2:]) == size:
+        return frames
+    lead = frames.shape[:-3]
+    flat = frames.reshape(-1, *frames.shape[-3:])
+    flat = torch.nn.functional.interpolate(
+        flat, size=size, mode="bilinear", align_corners=False, antialias=True
+    )
+    return flat.reshape(*lead, *flat.shape[-3:])
+
+
+def _stack_video_from_images(batch: dict[str, Tensor], config: FastWAMConfig) -> Tensor:
+    # Exclude the `*_is_pad` companion tensors that delta-timestamp loading adds alongside
+    # each camera (shape [B, T]); they share the `observation.images.` prefix but are not frames.
+    image_keys = sorted(k for k in batch if k.startswith("observation.images.") and not k.endswith("_is_pad"))
+    if not image_keys:
+        raise KeyError("FastWAM batch must contain `video` or `observation.images.*` keys.")
+    per_cam = (int(config.image_size[0]), int(config.image_size[1]) // len(image_keys))
+    images = [_resize_frames(batch[key], per_cam) for key in image_keys]
+    # Cameras concatenate along width (last dim) in both the single-frame and temporal case.
+    image = torch.cat(images, dim=-1) if len(images) > 1 else images[0]
+    if image.ndim == 4:
+        # [B, C, H, W]: a single frame (e.g. the live eval observation) -> repeat across time.
+        image = image.unsqueeze(2).repeat(1, 1, config.model_video_frames, 1, 1)
+    elif image.ndim == 5:
+        # [B, T, C, H, W]: temporal stack from delta-timestamp loading -> [B, C, T, H, W].
+        image = image.permute(0, 2, 1, 3, 4)
+    else:
+        raise ValueError(f"Expected image batch [B,C,H,W] or temporal [B,T,C,H,W], got {tuple(image.shape)}.")
+    return image
+
+
+def _input_image_from_batch(batch: dict[str, Tensor], config: FastWAMConfig) -> Tensor:
+    if "input_image" in batch:
+        return _prepare_infer_image(batch["input_image"], config)
+    video = batch.get("video")
+    if video is None:
+        video = _stack_video_from_images(batch, config)
+    if video.ndim == 5:
+        return _prepare_infer_image(video[:, :, 0], config)
+    if video.ndim == 4:
+        return _prepare_infer_image(video, config)
+    raise ValueError(f"Cannot build input image from tensor with shape {tuple(video.shape)}.")
+
+
+def _prepare_infer_image(image: Tensor, config: FastWAMConfig) -> Tensor:
+    if image.ndim == 3:
+        image = image.unsqueeze(0)
+    if image.ndim != 4:
+        raise ValueError(f"Expected image tensor [B,C,H,W] or [C,H,W], got {tuple(image.shape)}.")
+
+    # Resize to the full configured resolution (no-op when the video path already produced it, but
+    # also covers a directly-supplied `input_image`). The model owns its input resolution — see
+    # `_stack_video_from_images` — so we resize rather than assert on a mismatch.
+    target_h, target_w = int(config.image_size[0]), int(config.image_size[1])
+    return _resize_frames(image, (target_h, target_w))

src/lerobot/policies/fastwam/processor_fastwam.py

@@ -0,0 +1,142 @@
+# Copyright 2024 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Any
+
+import torch
+
+from lerobot.configs import PipelineFeatureType, PolicyFeature
+from lerobot.processor import (
+    ActionProcessorStep,
+    AddBatchDimensionProcessorStep,
+    DeviceProcessorStep,
+    NormalizerProcessorStep,
+    PolicyAction,
+    PolicyProcessorPipeline,
+    ProcessorStepRegistry,
+    RenameObservationsProcessorStep,
+    UnnormalizerProcessorStep,
+    policy_action_to_transition,
+    transition_to_policy_action,
+)
+from lerobot.utils.constants import (
+    POLICY_POSTPROCESSOR_DEFAULT_NAME,
+    POLICY_PREPROCESSOR_DEFAULT_NAME,
+)
+
+from .configuration_fastwam import FastWAMConfig
+
+
+@dataclass
+@ProcessorStepRegistry.register(name="fastwam_action_toggle_processor")
+class FastWAMActionToggleProcessorStep(ActionProcessorStep):
+    """Apply FastWAM LIBERO toggle semantics to configured action dimensions."""
+
+    toggle_dimensions: list[int]
+
+    def action(self, action: PolicyAction) -> PolicyAction:
+        if not self.toggle_dimensions:
+            return action
+        processed_action = action.clone()
+        action_dim = int(processed_action.shape[-1])
+        for dim in self.toggle_dimensions:
+            resolved_dim = dim if dim >= 0 else action_dim + dim
+            if resolved_dim < 0 or resolved_dim >= action_dim:
+                raise ValueError(
+                    f"FastWAM action toggle dimension {dim} is out of bounds for action dim {action_dim}."
+                )
+            value = processed_action[..., resolved_dim]
+            value = value * 2.0 - 1.0
+            processed_action[..., resolved_dim] = torch.sign(-value)
+        return processed_action
+
+    def get_config(self) -> dict[str, Any]:
+        return {"toggle_dimensions": self.toggle_dimensions}
+
+    def transform_features(
+        self, features: dict[PipelineFeatureType, dict[str, PolicyFeature]]
+    ) -> dict[PipelineFeatureType, dict[str, PolicyFeature]]:
+        return features
+
+
+def make_fastwam_pre_post_processors(
+    config: FastWAMConfig,
+    dataset_stats: dict[str, dict[str, torch.Tensor]] | None = None,
+) -> tuple[PolicyProcessorPipeline, PolicyProcessorPipeline]:
+    """Create LeRobot pre- and post-processing pipelines for FastWAM.
+
+    Args:
+        config (FastWAMConfig): Policy configuration controlling device and
+            normalization feature metadata.
+        dataset_stats (dict[str, dict[str, torch.Tensor]] | None): Optional
+            LeRobot dataset statistics used by normalization processors.
+
+    Returns:
+        tuple[PolicyProcessorPipeline, PolicyProcessorPipeline]: Input and
+        output processor pipelines discoverable by LeRobot.
+    """
+
+    # NOTE: no visual normalization here. VISUAL is IDENTITY (see configuration_fastwam.normalization_mapping)
+    # — images pass through in [0, 1] and the model maps them to the Wan VAE's [-1, 1] at the encode
+    # boundary. This is deliberate: `lerobot_train.py` overrides the normalizer stats with
+    # `dataset.meta.stats` when fine-tuning, and a real dataset's per-channel image std is the tiny
+    # frame-to-frame brightness variance, which would blow images far outside [-1,1] and saturate them.
+    # STATE/ACTION still normalize with dataset stats below.
+    normalization_stats: dict[str, dict[str, Any]] = dict(dataset_stats or {})
+
+    # NOTE: no resize step here. The model is the single authority on input resolution: it resizes
+    # each camera to the per-camera target (image_size split across cameras) in
+    # `_stack_video_from_images` / `_prepare_infer_image`, on every path (train forward, rollout and
+    # eval select_action). A preprocessor resize step would be both redundant (the model re-resizes
+    # anyway) and unsafe across fine-tuning: its `resize_size` would be inherited from the base
+    # checkpoint's camera geometry, not this dataset's, making the concatenation N_cameras x too wide.
+
+    input_steps = [
+        RenameObservationsProcessorStep(rename_map={}),
+        AddBatchDimensionProcessorStep(),
+        DeviceProcessorStep(device=config.device),
+        NormalizerProcessorStep(
+            features={**config.input_features, **config.output_features},
+            norm_map=config.normalization_mapping,
+            stats=normalization_stats,
+            device=config.device,
+        ),
+    ]
+    output_steps = [
+        UnnormalizerProcessorStep(
+            features=config.output_features,
+            norm_map=config.normalization_mapping,
+            stats=normalization_stats,
+        ),
+    ]
+    if config.toggle_action_dimensions:
+        output_steps.append(
+            FastWAMActionToggleProcessorStep(toggle_dimensions=config.toggle_action_dimensions)
+        )
+    output_steps.append(DeviceProcessorStep(device="cpu"))
+    return (
+        PolicyProcessorPipeline[dict[str, Any], dict[str, Any]](
+            steps=input_steps,
+            name=POLICY_PREPROCESSOR_DEFAULT_NAME,
+        ),
+        PolicyProcessorPipeline[PolicyAction, PolicyAction](
+            steps=output_steps,
+            name=POLICY_POSTPROCESSOR_DEFAULT_NAME,
+            to_transition=policy_action_to_transition,
+            to_output=transition_to_policy_action,
+        ),
+    )

src/lerobot/policies/fastwam/wan/README.md

@@ -0,0 +1,34 @@
+# FastWAM `wan` package
+
+This package holds FastWAM's model implementation. It mixes a small **vendored
+subset of the official Wan2.2 source tree** with FastWAM's own code, kept flat in
+a single directory.
+
+## Vendored from Wan2.2
+
+- Upstream repository: https://github.com/Wan-Video/Wan2.2
+- Upstream commit: `42bf4cfaa384bc21833865abc2f9e6c0e67233dc`
+- License: Apache-2.0, matching the license in `LICENSE.txt` from the upstream repository
+
+Copied files:
+
+- `model.py` (was `wan/modules/model.py`), trimmed: the flash-attention path
+  (the vendored `attention.py` and the block/model `forward`s) was removed.
+  FastWAM's DiT uses SDPA instead (see `video_dit.py`).
+- `get_sampling_sigmas` in `video_dit.py` (was `wan/utils/fm_solvers.py`), inlined
+  next to its only caller.
+
+This subset only backs FastWAM's **custom MoT video DiT**. The Wan2.2 VAE,
+UMT5 text encoder, and tokenizer are no longer vendored - they come from
+`diffusers.AutoencoderKLWan`, `transformers.UMT5EncoderModel`, and
+`transformers.AutoTokenizer` (see `components.py` and `adapters.py`).
+
+## FastWAM's own code
+
+- `video_dit.py` builds on `model` (`sinusoidal_embedding_1d`, `rope_params`,
+  `rope_apply`, …) and computes attention with SDPA (`fastwam_masked_attention`). Its
+  `WanContinuousFlowMatchScheduler` uses `get_sampling_sigmas` for Wan-compatible
+  inference timesteps.
+- `components.py` / `adapters.py` load the VAE, text encoder, tokenizer, and the
+  custom DiT weights.
+- `modular.py` defines the FastWAM model (`ActionDiT`, `MoT`, `FastWAM`, …).

src/lerobot/policies/fastwam/wan/__init__.py

@@ -0,0 +1,33 @@
+# Copyright 2024 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from .adapters import WanVideoVAE38
+from .components import (
+    build_wan_tokenizer,
+    load_pretrained_wan_text_encoder,
+    load_pretrained_wan_vae,
+)
+from .modular import ActionDiT, FastWAM, MoT
+from .video_dit import WanVideoDiT
+
+__all__ = [
+    "ActionDiT",
+    "FastWAM",
+    "MoT",
+    "WanVideoDiT",
+    "WanVideoVAE38",
+    "build_wan_tokenizer",
+    "load_pretrained_wan_text_encoder",
+    "load_pretrained_wan_vae",
+]

src/lerobot/policies/fastwam/wan/adapters.py

@@ -0,0 +1,108 @@
+# Copyright 2024 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+import torch
+
+if TYPE_CHECKING:
+    from diffusers import AutoencoderKLWan
+
+
+class WanVideoVAE38(torch.nn.Module):
+    """FastWAM VAE contract over `diffusers.AutoencoderKLWan` (Wan2.2-TI2V-5B).
+
+    16x spatial / 4x temporal compression, 48 latent channels. diffusers'
+    `AutoencoderKLWan` returns *raw* latents (it does not apply `latents_mean`/
+    `latents_std`), so `encode`/`decode` here apply the same standardization the
+    Wan reference uses — `(latents - mean) / std` — done in fp32 for stability.
+    `encode` uses the deterministic posterior mode, matching the original VAE
+    which returned the latent mean `mu`.
+    """
+
+    upsampling_factor = 16
+    temporal_downsample_factor = 4
+    z_dim = 48
+
+    def __init__(
+        self,
+        dtype: torch.dtype = torch.float32,
+        device: str | torch.device = "cuda",
+        *,
+        pretrained: AutoencoderKLWan,
+    ) -> None:
+        super().__init__()
+        # The Wan2.2 VAE is a fixed pretrained model — it is never trained from scratch,
+        # so a real `AutoencoderKLWan` (with weights) must always be supplied (loaded from
+        # the diffusers repo by `load_pretrained_wan_vae`). No random/offline build path.
+        self.vae = pretrained.to(device=device, dtype=dtype)
+
+        # Read the standardization stats from the VAE's own config (diffusers populates
+        # these from vae/config.json) — single source of truth, no local copy. diffusers'
+        # encode/decode return *raw* latents, so we apply (latent - mean) / std ourselves.
+        # Non-persistent: kept out of state_dict.
+        self.register_buffer(
+            "latents_mean",
+            torch.tensor(self.vae.config.latents_mean).view(1, self.z_dim, 1, 1, 1),
+            persistent=False,
+        )
+        self.register_buffer(
+            "latents_std",
+            torch.tensor(self.vae.config.latents_std).view(1, self.z_dim, 1, 1, 1),
+            persistent=False,
+        )
+
+    def _device_dtype(self) -> tuple[torch.device, torch.dtype]:
+        param = next(self.vae.parameters())
+        return param.device, param.dtype
+
+    def encode(
+        self,
+        videos: list[torch.Tensor] | torch.Tensor,
+        device: str | torch.device | None = None,
+        tiled: bool = False,
+        tile_size: tuple[int, int] = (34, 34),
+        tile_stride: tuple[int, int] = (18, 16),
+    ) -> torch.Tensor:
+        del device, tile_size, tile_stride
+        if tiled:
+            raise NotImplementedError("Tiled Wan2.2 VAE encoding is not supported by the FastWAM adapter.")
+        if isinstance(videos, (list, tuple)):
+            videos = torch.stack(list(videos))
+        dev, dtype = self._device_dtype()
+        mu = self.vae.encode(videos.to(device=dev, dtype=dtype)).latent_dist.mode().float()
+        mean = self.latents_mean.float().to(mu.device)
+        std = self.latents_std.float().to(mu.device)
+        return (mu - mean) / std
+
+    def decode(
+        self,
+        hidden_states: list[torch.Tensor] | torch.Tensor,
+        device: str | torch.device | None = None,
+        tiled: bool = False,
+        tile_size: tuple[int, int] = (34, 34),
+        tile_stride: tuple[int, int] = (18, 16),
+    ) -> torch.Tensor:
+        del device, tile_size, tile_stride
+        if tiled:
+            raise NotImplementedError("Tiled Wan2.2 VAE decoding is not supported by the FastWAM adapter.")
+        if isinstance(hidden_states, (list, tuple)):
+            hidden_states = torch.stack(list(hidden_states))
+        dev, dtype = self._device_dtype()
+        z = hidden_states.float()
+        z = z * self.latents_std.float().to(z.device) + self.latents_mean.float().to(z.device)
+        out = self.vae.decode(z.to(device=dev, dtype=dtype)).sample
+        return out.float().clamp_(-1.0, 1.0)

src/lerobot/policies/fastwam/wan/components.py

@@ -0,0 +1,175 @@
+# Copyright 2024 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+import logging
+from collections.abc import Sequence
+from pathlib import Path
+from typing import TYPE_CHECKING, Any
+
+import torch
+from huggingface_hub import snapshot_download
+from safetensors.torch import load_file
+
+from lerobot.utils.import_utils import _diffusers_available, _transformers_available, require_package
+
+if TYPE_CHECKING or _transformers_available:
+    from transformers import AutoTokenizer, UMT5EncoderModel
+else:
+    AutoTokenizer = None
+    UMT5EncoderModel = None
+
+if TYPE_CHECKING or _diffusers_available:
+    from diffusers import AutoencoderKLWan
+else:
+    AutoencoderKLWan = None
+
+from .adapters import WanVideoVAE38
+from .video_dit import WanVideoDiT
+
+logger = logging.getLogger(__name__)
+
+# The custom MoT video DiT still ships in the original (non-diffusers) Wan2.2
+# repo as sharded `diffusion_pytorch_model*.safetensors`; the VAE and UMT5 text
+# encoder come from the diffusers conversion. Tokenizer is the stock UMT5 one.
+WAN_DIT_PATTERN = "diffusion_pytorch_model*.safetensors"
+WAN_T5_TOKENIZER = "google/umt5-xxl"
+WAN22_DIFFUSERS_MODEL_ID = "Wan-AI/Wan2.2-TI2V-5B-Diffusers"
+
+
+class WanTextEncoder(torch.nn.Module):
+    """FastWAM text-encoder contract over `transformers.UMT5EncoderModel`.
+
+    Exposes `.dim` (hidden size) and `forward(ids, mask) -> [B, L, dim]`, matching
+    the call in `FastWAM.encode_prompt`.
+    """
+
+    def __init__(
+        self,
+        dtype: torch.dtype = torch.bfloat16,
+        device: str | torch.device = "cuda",
+        *,
+        pretrained: torch.nn.Module,
+    ) -> None:
+        super().__init__()
+        # UMT5-XXL is a fixed pretrained encoder — never trained from scratch, so a real
+        # `UMT5EncoderModel` (with weights) must always be supplied (loaded from the
+        # diffusers repo by `load_pretrained_wan_text_encoder`). No random/offline build.
+        self.model = pretrained.to(device=device, dtype=dtype)
+        self.dim = int(self.model.config.d_model)
+
+    def forward(self, ids: torch.Tensor, mask: torch.Tensor) -> torch.Tensor:
+        return self.model(input_ids=ids, attention_mask=mask.long()).last_hidden_state
+
+
+class WanTokenizer:
+    """UMT5 tokenizer wrapper returning `(input_ids, attention_mask)` like the
+    FastWAM call site expects."""
+
+    def __init__(self, name: str = WAN_T5_TOKENIZER, seq_len: int = 512) -> None:
+        require_package("transformers", extra="fastwam")
+        self.tokenizer = AutoTokenizer.from_pretrained(name)
+        self.seq_len = int(seq_len)
+
+    def __call__(
+        self,
+        sequence: str | Sequence[str],
+        return_mask: bool = False,
+        add_special_tokens: bool = True,
+        **_: Any,
+    ):
+        if isinstance(sequence, str):
+            sequence = [sequence]
+        out = self.tokenizer(
+            list(sequence),
+            padding="max_length",
+            truncation=True,
+            max_length=self.seq_len,
+            add_special_tokens=add_special_tokens,
+            return_tensors="pt",
+        )
+        if return_mask:
+            return out.input_ids, out.attention_mask
+        return out.input_ids
+
+
+def build_wan_tokenizer(*, model_id: str = WAN_T5_TOKENIZER, tokenizer_max_len: int) -> WanTokenizer:
+    return WanTokenizer(name=model_id, seq_len=int(tokenizer_max_len))
+
+
+def load_pretrained_wan_vae(*, torch_dtype: torch.dtype, device: str) -> WanVideoVAE38:
+    """Load real Wan2.2 VAE weights from the diffusers repo (offline base creation)."""
+    require_package("diffusers", extra="fastwam")
+    vae = AutoencoderKLWan.from_pretrained(WAN22_DIFFUSERS_MODEL_ID, subfolder="vae", torch_dtype=torch_dtype)
+    return WanVideoVAE38(dtype=torch_dtype, device=device, pretrained=vae)
+
+
+def load_pretrained_wan_text_encoder(
+    *,
+    model_id: str = WAN22_DIFFUSERS_MODEL_ID,
+    subfolder: str | None = "text_encoder",
+    torch_dtype: torch.dtype,
+    device: str,
+) -> WanTextEncoder:
+    """Load UMT5-XXL encoder weights (defaults to the Wan2.2 diffusers repo).
+
+    Must stay compatible with the tokenizer (see `build_wan_tokenizer`): the encoder's
+    embedding table is indexed by the tokenizer's vocabulary.
+    """
+    require_package("transformers", extra="fastwam")
+    encoder = UMT5EncoderModel.from_pretrained(model_id, subfolder=subfolder, torch_dtype=torch_dtype)
+    return WanTextEncoder(dtype=torch_dtype, device=device, pretrained=encoder)
+
+
+def resolve_wan_dit_paths(
+    model_id_or_path: str | Path,
+    *,
+    cache_dir: str | Path | None = None,
+    local_files_only: bool = False,
+    revision: str | None = None,
+) -> list[Path]:
+    """Resolve the custom MoT DiT shards from the original Wan2.2 repo or a local dir."""
+    path = Path(model_id_or_path).expanduser()
+    if path.is_dir():
+        return sorted(path.glob(WAN_DIT_PATTERN))
+
+    snapshot_path = snapshot_download(
+        repo_id=str(model_id_or_path),
+        revision=revision,
+        cache_dir=cache_dir,
+        local_files_only=local_files_only,
+        allow_patterns=[WAN_DIT_PATTERN],
+    )
+    return sorted(Path(snapshot_path).glob(WAN_DIT_PATTERN))
+
+
+def load_wan_video_dit(
+    paths: list[str | Path],
+    *,
+    dit_config: dict[str, Any],
+    torch_dtype: torch.dtype,
+    device: str,
+) -> WanVideoDiT:
+    model = WanVideoDiT(**dit_config)
+    state_dict = _read_wan_dit_safetensors(paths)
+    model.load_state_dict(state_dict, strict=False)
+    return model.to(device=device, dtype=torch_dtype)
+
+
+def _read_wan_dit_safetensors(paths: list[str | Path]) -> dict[str, torch.Tensor]:
+    state_dict = {}
+    for path in paths:
+        state_dict.update(load_file(str(path), device="cpu"))
+    return state_dict

src/lerobot/policies/fastwam/wan/model.py

@@ -0,0 +1,341 @@
+# Copyright 2024-2025 The Alibaba Wan Team Authors. All rights reserved.
+import math
+
+import torch
+import torch.nn as nn
+
+
+def sinusoidal_embedding_1d(dim, position):
+    # preprocess
+    if dim % 2 != 0:
+        raise ValueError(f"dim must be even, got {dim}.")
+    half = dim // 2
+    position = position.type(torch.float64)
+
+    # calculation
+    sinusoid = torch.outer(position, torch.pow(10000, -torch.arange(half).to(position).div(half)))
+    x = torch.cat([torch.cos(sinusoid), torch.sin(sinusoid)], dim=1)
+    return x
+
+
+@torch.amp.autocast("cuda", enabled=False)
+def rope_params(max_seq_len, dim, theta=10000):
+    if dim % 2 != 0:
+        raise ValueError(f"dim must be even, got {dim}.")
+    freqs = torch.outer(
+        torch.arange(max_seq_len), 1.0 / torch.pow(theta, torch.arange(0, dim, 2).to(torch.float64).div(dim))
+    )
+    freqs = torch.polar(torch.ones_like(freqs), freqs)
+    return freqs
+
+
+@torch.amp.autocast("cuda", enabled=False)
+def rope_apply(x, grid_sizes, freqs):
+    n, c = x.size(2), x.size(3) // 2
+
+    # split freqs
+    freqs = freqs.split([c - 2 * (c // 3), c // 3, c // 3], dim=1)
+
+    # loop over samples
+    output = []
+    for i, (f, h, w) in enumerate(grid_sizes.tolist()):
+        seq_len = f * h * w
+
+        # precompute multipliers
+        x_i = torch.view_as_complex(x[i, :seq_len].to(torch.float64).reshape(seq_len, n, -1, 2))
+        freqs_i = torch.cat(
+            [
+                freqs[0][:f].view(f, 1, 1, -1).expand(f, h, w, -1),
+                freqs[1][:h].view(1, h, 1, -1).expand(f, h, w, -1),
+                freqs[2][:w].view(1, 1, w, -1).expand(f, h, w, -1),
+            ],
+            dim=-1,
+        ).reshape(seq_len, 1, -1)
+
+        # apply rotary embedding
+        x_i = torch.view_as_real(x_i * freqs_i).flatten(2)
+        x_i = torch.cat([x_i, x[i, seq_len:]])
+
+        # append to collection
+        output.append(x_i)
+    return torch.stack(output).float()
+
+
+class WanRMSNorm(nn.Module):
+    def __init__(self, dim, eps=1e-5):
+        super().__init__()
+        self.dim = dim
+        self.eps = eps
+        self.weight = nn.Parameter(torch.ones(dim))
+
+    def forward(self, x):
+        r"""
+        Args:
+            x(Tensor): Shape [B, L, C]
+        """
+        return self._norm(x.float()).type_as(x) * self.weight
+
+    def _norm(self, x):
+        return x * torch.rsqrt(x.pow(2).mean(dim=-1, keepdim=True) + self.eps)
+
+
+class WanLayerNorm(nn.LayerNorm):
+    def __init__(self, dim, eps=1e-6, elementwise_affine=False):
+        super().__init__(dim, elementwise_affine=elementwise_affine, eps=eps)
+
+    def forward(self, x):
+        r"""
+        Args:
+            x(Tensor): Shape [B, L, C]
+        """
+        return super().forward(x.float()).type_as(x)
+
+
+class WanSelfAttention(nn.Module):
+    def __init__(self, dim, num_heads, qk_norm=True, eps=1e-6):
+        if dim % num_heads != 0:
+            raise ValueError(f"dim ({dim}) must be divisible by num_heads ({num_heads}).")
+        super().__init__()
+        self.num_heads = num_heads
+        self.head_dim = dim // num_heads
+
+        # layers
+        self.q = nn.Linear(dim, dim)
+        self.k = nn.Linear(dim, dim)
+        self.v = nn.Linear(dim, dim)
+        self.o = nn.Linear(dim, dim)
+        self.norm_q = WanRMSNorm(dim, eps=eps) if qk_norm else nn.Identity()
+        self.norm_k = WanRMSNorm(dim, eps=eps) if qk_norm else nn.Identity()
+
+    # NOTE: FastWAM never runs the upstream Wan attention forward. FastWAMAttentionBlock
+    # reuses only the q/k/v/o/norm submodules defined above and computes attention via
+    # `fastwam_masked_attention` (SDPA). The original flash-attention forward was removed,
+    # which also collapsed the former WanCrossAttention subclass into this class (it only
+    # differed by its forward): self- and cross-attention now share the same projection module.
+
+
+class WanAttentionBlock(nn.Module):
+    def __init__(self, dim, ffn_dim, num_heads, qk_norm=True, cross_attn_norm=False, eps=1e-6):
+        super().__init__()
+        self.dim = dim
+        self.ffn_dim = ffn_dim
+        self.num_heads = num_heads
+        self.qk_norm = qk_norm
+        self.cross_attn_norm = cross_attn_norm
+        self.eps = eps
+
+        # layers
+        self.norm1 = WanLayerNorm(dim, eps)
+        self.self_attn = WanSelfAttention(dim, num_heads, qk_norm, eps)
+        self.norm3 = WanLayerNorm(dim, eps, elementwise_affine=True) if cross_attn_norm else nn.Identity()
+        self.cross_attn = WanSelfAttention(dim, num_heads, qk_norm, eps)
+        self.norm2 = WanLayerNorm(dim, eps)
+        self.ffn = nn.Sequential(
+            nn.Linear(dim, ffn_dim), nn.GELU(approximate="tanh"), nn.Linear(ffn_dim, dim)
+        )
+
+        # modulation
+        self.modulation = nn.Parameter(torch.randn(1, 6, dim) / dim**0.5)
+
+    # NOTE: The upstream Wan block forward (self-attention + cross-attention + FFN via
+    # flash-attention) was removed. FastWAM subclasses this block as FastWAMAttentionBlock
+    # and overrides forward to use SDPA with explicit boolean masks; only __init__ (the
+    # norm/attention/ffn submodules) is reused here.
+
+
+class Head(nn.Module):
+    def __init__(self, dim, out_dim, patch_size, eps=1e-6):
+        super().__init__()
+        self.dim = dim
+        self.out_dim = out_dim
+        self.patch_size = patch_size
+        self.eps = eps
+
+        # layers
+        out_dim = math.prod(patch_size) * out_dim
+        self.norm = WanLayerNorm(dim, eps)
+        self.head = nn.Linear(dim, out_dim)
+
+        # modulation
+        self.modulation = nn.Parameter(torch.randn(1, 2, dim) / dim**0.5)
+
+    def forward(self, x, e):
+        r"""
+        Args:
+            x(Tensor): Shape [B, L1, C]
+            e(Tensor): Shape [B, L1, C]
+        """
+        with torch.amp.autocast("cuda", dtype=torch.float32):
+            e = (self.modulation.unsqueeze(0) + e.unsqueeze(2)).chunk(2, dim=2)
+            x = self.head(self.norm(x) * (1 + e[1].squeeze(2)) + e[0].squeeze(2))
+        return x
+
+
+class WanModel(nn.Module):
+    r"""
+    Wan diffusion backbone supporting both text-to-video and image-to-video.
+    """
+
+    def __init__(
+        self,
+        model_type="t2v",
+        patch_size=(1, 2, 2),
+        text_len=512,
+        in_dim=16,
+        dim=2048,
+        ffn_dim=8192,
+        freq_dim=256,
+        text_dim=4096,
+        out_dim=16,
+        num_heads=16,
+        num_layers=32,
+        qk_norm=True,
+        cross_attn_norm=True,
+        eps=1e-6,
+    ):
+        r"""
+        Initialize the diffusion model backbone.
+
+        Args:
+            model_type (`str`, *optional*, defaults to 't2v'):
+                Model variant - 't2v' (text-to-video) or 'i2v' (image-to-video)
+            patch_size (`tuple`, *optional*, defaults to (1, 2, 2)):
+                3D patch dimensions for video embedding (t_patch, h_patch, w_patch)
+            text_len (`int`, *optional*, defaults to 512):
+                Fixed length for text embeddings
+            in_dim (`int`, *optional*, defaults to 16):
+                Input video channels (C_in)
+            dim (`int`, *optional*, defaults to 2048):
+                Hidden dimension of the transformer
+            ffn_dim (`int`, *optional*, defaults to 8192):
+                Intermediate dimension in feed-forward network
+            freq_dim (`int`, *optional*, defaults to 256):
+                Dimension for sinusoidal time embeddings
+            text_dim (`int`, *optional*, defaults to 4096):
+                Input dimension for text embeddings
+            out_dim (`int`, *optional*, defaults to 16):
+                Output video channels (C_out)
+            num_heads (`int`, *optional*, defaults to 16):
+                Number of attention heads
+            num_layers (`int`, *optional*, defaults to 32):
+                Number of transformer blocks
+            qk_norm (`bool`, *optional*, defaults to True):
+                Enable query/key normalization
+            cross_attn_norm (`bool`, *optional*, defaults to False):
+                Enable cross-attention normalization
+            eps (`float`, *optional*, defaults to 1e-6):
+                Epsilon value for normalization layers
+        """
+
+        super().__init__()
+
+        if model_type not in ["t2v", "i2v", "ti2v", "s2v"]:
+            raise ValueError(f"model_type must be one of ['t2v', 'i2v', 'ti2v', 's2v'], got {model_type!r}.")
+        self.model_type = model_type
+
+        self.patch_size = patch_size
+        self.text_len = text_len
+        self.in_dim = in_dim
+        self.dim = dim
+        self.ffn_dim = ffn_dim
+        self.freq_dim = freq_dim
+        self.text_dim = text_dim
+        self.out_dim = out_dim
+        self.num_heads = num_heads
+        self.num_layers = num_layers
+        self.qk_norm = qk_norm
+        self.cross_attn_norm = cross_attn_norm
+        self.eps = eps
+
+        # embeddings
+        self.patch_embedding = nn.Conv3d(in_dim, dim, kernel_size=patch_size, stride=patch_size)
+        self.text_embedding = nn.Sequential(
+            nn.Linear(text_dim, dim), nn.GELU(approximate="tanh"), nn.Linear(dim, dim)
+        )
+
+        self.time_embedding = nn.Sequential(nn.Linear(freq_dim, dim), nn.SiLU(), nn.Linear(dim, dim))
+        self.time_projection = nn.Sequential(nn.SiLU(), nn.Linear(dim, dim * 6))
+
+        # blocks
+        self.blocks = nn.ModuleList(
+            [
+                WanAttentionBlock(dim, ffn_dim, num_heads, qk_norm, cross_attn_norm, eps)
+                for _ in range(num_layers)
+            ]
+        )
+
+        # head
+        self.head = Head(dim, out_dim, patch_size, eps)
+
+        # buffers (don't use register_buffer otherwise dtype will be changed in to())
+        if (dim % num_heads) != 0 or (dim // num_heads) % 2 != 0:
+            raise ValueError(
+                f"dim ({dim}) must be divisible by num_heads ({num_heads}) with an even head dim."
+            )
+        d = dim // num_heads
+        self.freqs = torch.cat(
+            [
+                rope_params(1024, d - 4 * (d // 6)),
+                rope_params(1024, 2 * (d // 6)),
+                rope_params(1024, 2 * (d // 6)),
+            ],
+            dim=1,
+        )
+
+        # initialize weights
+        self.init_weights()
+
+    # NOTE: The upstream Wan diffusion forward (flash-attention based) was removed.
+    # FastWAM's WanVideoDiT subclasses this model, rebuilds `self.blocks` with
+    # FastWAMAttentionBlock, and provides its own SDPA-based forward. Only the
+    # constructor (embeddings, blocks, head, rope buffers) and the helpers below
+    # (unpatchify / init_weights) are reused. WanModel is never run directly.
+
+    def unpatchify(self, x, grid_sizes):
+        r"""
+        Reconstruct video tensors from patch embeddings.
+
+        Args:
+            x (List[Tensor]):
+                List of patchified features, each with shape [L, C_out * prod(patch_size)]
+            grid_sizes (Tensor):
+                Original spatial-temporal grid dimensions before patching,
+                    shape [B, 3] (3 dimensions correspond to F_patches, H_patches, W_patches)
+
+        Returns:
+            List[Tensor]:
+                Reconstructed video tensors with shape [C_out, F, H / 8, W / 8]
+        """
+
+        c = self.out_dim
+        out = []
+        for u, v in zip(x, grid_sizes.tolist(), strict=False):
+            u = u[: math.prod(v)].view(*v, *self.patch_size, c)
+            u = torch.einsum("fhwpqrc->cfphqwr", u)
+            u = u.reshape(c, *[i * j for i, j in zip(v, self.patch_size, strict=False)])
+            out.append(u)
+        return out
+
+    def init_weights(self):
+        r"""
+        Initialize model parameters using Xavier initialization.
+        """
+
+        # basic init
+        for m in self.modules():
+            if isinstance(m, nn.Linear):
+                nn.init.xavier_uniform_(m.weight)
+                if m.bias is not None:
+                    nn.init.zeros_(m.bias)
+
+        # init embeddings
+        nn.init.xavier_uniform_(self.patch_embedding.weight.flatten(1))
+        for m in self.text_embedding.modules():
+            if isinstance(m, nn.Linear):
+                nn.init.normal_(m.weight, std=0.02)
+        for m in self.time_embedding.modules():
+            if isinstance(m, nn.Linear):
+                nn.init.normal_(m.weight, std=0.02)
+
+        # init output layer
+        nn.init.zeros_(self.head.head.weight)

src/lerobot/policies/fastwam/wan/video_dit.py

@@ -0,0 +1,800 @@
+# Copyright 2024 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+from typing import Any
+
+import numpy as np
+import torch
+import torch.nn as nn
+import torch.nn.functional as functional
+from einops import rearrange
+
+from .model import (
+    WanAttentionBlock,
+    WanLayerNorm,
+    WanModel,
+    WanRMSNorm,
+    rope_apply,
+    rope_params,
+    sinusoidal_embedding_1d,
+)
+
+logger = logging.getLogger(__name__)
+
+
+def get_sampling_sigmas(sampling_steps, shift):
+    # Vendored from Wan2.2 (formerly wan/utils/fm_solvers.py); computes the
+    # noise-level (sigma) schedule for Wan-compatible flow-matching inference.
+    sigma = np.linspace(1, 0, sampling_steps + 1)[:sampling_steps]
+    sigma = shift * sigma / (1 + (shift - 1) * sigma)
+    return sigma
+
+
+def create_custom_forward(module):
+    def custom_forward(*inputs, **kwargs):
+        return module(*inputs, **kwargs)
+
+    return custom_forward
+
+
+def gradient_checkpoint_forward(
+    model,
+    use_gradient_checkpointing,
+    *args,
+    **kwargs,
+):
+    if use_gradient_checkpointing:
+        model_output = torch.utils.checkpoint.checkpoint(
+            create_custom_forward(model),
+            *args,
+            **kwargs,
+            use_reentrant=False,
+        )
+    else:
+        model_output = model(*args, **kwargs)
+    return model_output
+
+
+def fastwam_masked_attention(
+    q: torch.Tensor,
+    k: torch.Tensor,
+    v: torch.Tensor,
+    num_heads: int,
+    ctx_mask: torch.Tensor | None = None,
+    fp32_attention: bool = True,
+) -> torch.Tensor:
+    """FastWAM masked attention wrapper for MoT masks and CPU test coverage.
+
+    The official Wan attention implementation is still used as the source of
+    the projection/norm modules. This wrapper only replaces the final attention
+    kernel because FastWAM needs explicit boolean masks for video/action MoT
+    routing, while the upstream FlashAttention path accepts sequence lengths
+    but not arbitrary [query, key] masks.
+    """
+
+    q = rearrange(q, "b s (n d) -> b n s d", n=num_heads)
+    k = rearrange(k, "b s (n d) -> b n s d", n=num_heads)
+    v = rearrange(v, "b s (n d) -> b n s d", n=num_heads)
+    if fp32_attention:
+        q = q.float()
+        k = k.float()
+        v = v.float()
+    else:
+        q = q.to(dtype=v.dtype)
+        k = k.to(dtype=v.dtype)
+    x = functional.scaled_dot_product_attention(q, k, v, attn_mask=ctx_mask)
+    return rearrange(x, "b n s d -> b s (n d)", n=num_heads)
+
+
+def modulate(x: torch.Tensor, shift: torch.Tensor, scale: torch.Tensor):
+    return x * (1 + scale) + shift
+
+
+class WanContinuousFlowMatchScheduler:
+    """Continuous-time Flow-Matching scheduler with shift-based Wan sampling."""
+
+    def __init__(self, num_train_timesteps: int = 1000, shift: float = 5.0, eps: float = 1e-10):
+        if num_train_timesteps <= 0:
+            raise ValueError(f"`num_train_timesteps` must be positive, got {num_train_timesteps}")
+        if shift <= 0:
+            raise ValueError(f"`shift` must be positive, got {shift}")
+        self.num_train_timesteps = int(num_train_timesteps)
+        self.shift = float(shift)
+        self.eps = float(eps)
+        self._y_min, self._weight_norm_const = self._precompute_training_weight_stats()
+
+    @staticmethod
+    def _phi(u: torch.Tensor, shift: float) -> torch.Tensor:
+        return shift * u / (1.0 + (shift - 1.0) * u)
+
+    def _precompute_training_weight_stats(self) -> tuple[float, float]:
+        steps = self.num_train_timesteps
+        u_grid = torch.linspace(1.0, 0.0, steps + 1, dtype=torch.float64)[:-1]
+        t_grid = self._phi(u_grid, self.shift) * float(steps)
+        y_grid = torch.exp(-2.0 * ((t_grid - (steps / 2.0)) / steps) ** 2)
+        y_min = float(y_grid.min().item())
+        y_shifted_grid = y_grid - y_min
+        norm_const = float(y_shifted_grid.mean().item())
+        return y_min, norm_const
+
+    def sample_training_t(self, batch_size: int, device: torch.device, dtype: torch.dtype) -> torch.Tensor:
+        if batch_size <= 0:
+            raise ValueError(f"`batch_size` must be positive, got {batch_size}")
+        u = torch.rand((batch_size,), device=device, dtype=torch.float32)
+        sigma = self._phi(u, self.shift)
+        timestep = sigma * float(self.num_train_timesteps)
+        return timestep.to(dtype=dtype)
+
+    def training_weight(self, timestep: torch.Tensor) -> torch.Tensor:
+        t = timestep.to(dtype=torch.float32)
+        steps = float(self.num_train_timesteps)
+        y = torch.exp(-2.0 * ((t - (steps / 2.0)) / steps) ** 2)
+        y_shifted = y - self._y_min
+        weight = y_shifted / (self._weight_norm_const + self.eps)
+        if weight.numel() == 1:
+            return weight.reshape(())
+        return weight
+
+    def add_noise(
+        self, original_samples: torch.Tensor, noise: torch.Tensor, timestep: torch.Tensor
+    ) -> torch.Tensor:
+        sigma = (timestep / float(self.num_train_timesteps)).to(
+            original_samples.device, dtype=original_samples.dtype
+        )
+        if sigma.ndim == 0:
+            return (1 - sigma) * original_samples + sigma * noise
+        sigma = sigma.view(-1, *([1] * (original_samples.ndim - 1)))
+        return (1 - sigma) * original_samples + sigma * noise
+
+    @staticmethod
+    def training_target(sample: torch.Tensor, noise: torch.Tensor, timestep: torch.Tensor) -> torch.Tensor:
+        del timestep
+        return noise - sample
+
+    def build_inference_schedule(
+        self,
+        num_inference_steps: int,
+        device: torch.device,
+        dtype: torch.dtype,
+        shift_override: float | None = None,
+    ) -> tuple[torch.Tensor, torch.Tensor]:
+        if num_inference_steps <= 0:
+            raise ValueError(f"`num_inference_steps` must be positive, got {num_inference_steps}")
+        shift = self.shift if shift_override is None else float(shift_override)
+        if shift <= 0:
+            raise ValueError(f"`shift` must be positive, got {shift}")
+
+        sigma_steps = torch.as_tensor(
+            get_sampling_sigmas(num_inference_steps, shift),
+            device=device,
+            dtype=torch.float32,
+        )
+        timesteps = sigma_steps * float(self.num_train_timesteps)
+        sigma_next = torch.cat([sigma_steps[1:], sigma_steps.new_zeros(1)])
+        deltas = sigma_next - sigma_steps
+        return timesteps.to(dtype=dtype), deltas.to(dtype=dtype)
+
+    @staticmethod
+    def step(model_output: torch.Tensor, delta: torch.Tensor, sample: torch.Tensor) -> torch.Tensor:
+        delta = delta.to(sample.device, dtype=sample.dtype)
+        if delta.ndim == 0:
+            return sample + model_output * delta
+        delta = delta.view(-1, *([1] * (sample.ndim - 1)))
+        return sample + model_output * delta
+
+
+def precompute_freqs_cis(dim: int, end: int = 1024, theta: float = 10000.0):
+    return rope_params(end, dim, theta)
+
+
+def apply_dense_rope(x: torch.Tensor, freqs: torch.Tensor, num_heads: int) -> torch.Tensor:
+    x = rearrange(x, "b s (n d) -> b s n d", n=num_heads)
+    x_out = torch.view_as_complex(x.to(torch.float32).reshape(x.shape[0], x.shape[1], x.shape[2], -1, 2))
+    freqs = freqs.to(torch.complex64) if freqs.device.type == "npu" else freqs
+    x_out = torch.view_as_real(x_out * freqs).flatten(2)
+    return x_out.to(x.dtype)
+
+
+def _linear_input(linear: nn.Linear, x: torch.Tensor) -> torch.Tensor:
+    return x.to(dtype=linear.weight.dtype)
+
+
+def _wan_layer_norm(norm: nn.Module, x: torch.Tensor) -> torch.Tensor:
+    if isinstance(norm, WanLayerNorm) and norm.weight is not None:
+        weight = norm.weight.float()
+        bias = norm.bias.float() if norm.bias is not None else None
+        return functional.layer_norm(x.float(), norm.normalized_shape, weight, bias, norm.eps).to(
+            dtype=x.dtype
+        )
+    return norm(x)
+
+
+def create_group_causal_attn_mask(
+    num_temporal_groups: int, num_query_per_group: int, num_key_per_group: int, mode: str = "causal"
+) -> torch.Tensor:
+    if mode not in ["causal", "group_diagonal"]:
+        raise ValueError(f"`mode` must be 'causal' or 'group_diagonal', got {mode}.")
+    if num_temporal_groups <= 0:
+        raise ValueError(f"`num_temporal_groups` must be positive, got {num_temporal_groups}.")
+    if num_query_per_group <= 0:
+        raise ValueError(f"`num_query_per_group` must be positive, got {num_query_per_group}.")
+    if num_key_per_group <= 0:
+        raise ValueError(f"`num_key_per_group` must be positive, got {num_key_per_group}.")
+
+    total_num_query_tokens = num_temporal_groups * num_query_per_group
+    total_num_key_tokens = num_temporal_groups * num_key_per_group
+    query_time_indices = torch.arange(num_temporal_groups).repeat_interleave(num_query_per_group).unsqueeze(1)
+    key_time_indices = torch.arange(num_temporal_groups).repeat_interleave(num_key_per_group).unsqueeze(0)
+
+    if mode == "causal":
+        attn_mask = query_time_indices >= key_time_indices
+    else:
+        attn_mask = query_time_indices == key_time_indices
+
+    if attn_mask.shape != (total_num_query_tokens, total_num_key_tokens):
+        raise RuntimeError("Attention mask shape mismatch.")
+    return attn_mask
+
+
+class FastWAMAttentionBlock(WanAttentionBlock):
+    """Wan attention block with FastWAM's arbitrary boolean mask support."""
+
+    def __init__(
+        self,
+        hidden_dim: int,
+        attn_head_dim: int,
+        num_heads: int,
+        ffn_dim: int,
+        eps: float = 1e-6,
+        fp32_attention: bool = True,
+    ):
+        attention_dim = attn_head_dim * num_heads
+        if hidden_dim == attention_dim:
+            super().__init__(
+                dim=hidden_dim,
+                ffn_dim=ffn_dim,
+                num_heads=num_heads,
+                qk_norm=True,
+                cross_attn_norm=True,
+                eps=eps,
+            )
+        else:
+            nn.Module.__init__(self)
+            self.dim = hidden_dim
+            self.ffn_dim = ffn_dim
+            self.num_heads = num_heads
+            self.qk_norm = True
+            self.cross_attn_norm = True
+            self.eps = eps
+            self.norm1 = WanLayerNorm(hidden_dim, eps)
+            self.self_attn = _FastWAMProjectedAttention(hidden_dim, attention_dim, num_heads, eps)
+            self.norm3 = WanLayerNorm(hidden_dim, eps, elementwise_affine=True)
+            self.cross_attn = _FastWAMProjectedAttention(hidden_dim, attention_dim, num_heads, eps)
+            self.norm2 = WanLayerNorm(hidden_dim, eps)
+            self.ffn = nn.Sequential(
+                nn.Linear(hidden_dim, ffn_dim),
+                nn.GELU(approximate="tanh"),
+                nn.Linear(ffn_dim, hidden_dim),
+            )
+            self.modulation = nn.Parameter(torch.randn(1, 6, hidden_dim) / hidden_dim**0.5)
+        self.attn_head_dim = attn_head_dim
+        self.fp32_attention = bool(fp32_attention)
+
+    @staticmethod
+    def split_modulation(block, t_mod: torch.Tensor):
+        has_seq = len(t_mod.shape) == 4
+        chunk_dim = 2 if has_seq else 1
+
+        base_mod = block.modulation.to(dtype=t_mod.dtype, device=t_mod.device)
+        shift_msa, scale_msa, gate_msa, shift_mlp, scale_mlp, gate_mlp = (base_mod + t_mod).chunk(
+            6, dim=chunk_dim
+        )
+        if has_seq:
+            shift_msa, scale_msa, gate_msa, shift_mlp, scale_mlp, gate_mlp = (
+                shift_msa.squeeze(2),
+                scale_msa.squeeze(2),
+                gate_msa.squeeze(2),
+                shift_mlp.squeeze(2),
+                scale_mlp.squeeze(2),
+                gate_mlp.squeeze(2),
+            )
+        return shift_msa, scale_msa, gate_msa, shift_mlp, scale_mlp, gate_mlp
+
+    def project_self_attention(
+        self, x: torch.Tensor, freqs: torch.Tensor | dict[str, torch.Tensor]
+    ) -> tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
+        q = self.self_attn.norm_q(self.self_attn.q(x))
+        k = self.self_attn.norm_k(self.self_attn.k(x))
+        v = self.self_attn.v(x)
+        if isinstance(freqs, dict):
+            b, s = x.shape[:2]
+            q = rope_apply(
+                q.view(b, s, self.num_heads, self.attn_head_dim),
+                freqs["grid_sizes"],
+                freqs["freqs"],
+            ).flatten(2)
+            k = rope_apply(
+                k.view(b, s, self.num_heads, self.attn_head_dim),
+                freqs["grid_sizes"],
+                freqs["freqs"],
+            ).flatten(2)
+        else:
+            q = apply_dense_rope(q, freqs, self.num_heads)
+            k = apply_dense_rope(k, freqs, self.num_heads)
+        return q, k, v
+
+    def apply_cross_attention(
+        self, x: torch.Tensor, context: torch.Tensor, context_mask: torch.Tensor | None = None
+    ) -> torch.Tensor:
+        if context_mask is not None and context_mask.dim() == 3:
+            context_mask = context_mask.unsqueeze(1)
+        attn = self.cross_attn
+        b, n, d = x.size(0), attn.num_heads, attn.head_dim
+        q = attn.norm_q(attn.q(x)).view(b, -1, n * d)
+        k = attn.norm_k(attn.k(context)).view(b, -1, n * d)
+        v = attn.v(context).view(b, -1, n * d)
+        x = fastwam_masked_attention(
+            q=q,
+            k=k,
+            v=v,
+            num_heads=n,
+            ctx_mask=context_mask,
+            fp32_attention=self.fp32_attention,
+        )
+        return attn.o(_linear_input(attn.o, x))
+
+    def project_self_attention_output(self, x: torch.Tensor) -> torch.Tensor:
+        return self.self_attn.o(_linear_input(self.self_attn.o, x))
+
+    def apply_norm1(self, x: torch.Tensor) -> torch.Tensor:
+        return _wan_layer_norm(self.norm1, x)
+
+    def apply_norm2(self, x: torch.Tensor) -> torch.Tensor:
+        return _wan_layer_norm(self.norm2, x)
+
+    def apply_norm3(self, x: torch.Tensor) -> torch.Tensor:
+        return _wan_layer_norm(self.norm3, x)
+
+    def forward(
+        self,
+        x: torch.Tensor,
+        context: torch.Tensor,
+        t_mod: torch.Tensor,
+        freqs: torch.Tensor,
+        context_mask: torch.Tensor | None = None,
+        self_attn_mask: torch.Tensor | None = None,
+    ) -> torch.Tensor:
+        shift_msa, scale_msa, gate_msa, shift_mlp, scale_mlp, gate_mlp = self.split_modulation(self, t_mod)
+        residual_x = x
+        attn_input = modulate(self.apply_norm1(x), shift_msa, scale_msa)
+        q, k, v = self.project_self_attention(attn_input, freqs)
+        y = fastwam_masked_attention(
+            q=q,
+            k=k,
+            v=v,
+            num_heads=self.num_heads,
+            ctx_mask=self_attn_mask,
+            fp32_attention=self.fp32_attention,
+        )
+        x = residual_x + gate_msa * self.project_self_attention_output(y)
+        x = x + self.apply_cross_attention(self.apply_norm3(x), context, context_mask=context_mask)
+        mlp_input = modulate(self.apply_norm2(x), shift_mlp, scale_mlp)
+        return x + gate_mlp * self.ffn(mlp_input)
+
+
+class _FastWAMProjectedAttention(nn.Module):
+    def __init__(self, hidden_dim: int, attention_dim: int, num_heads: int, eps: float):
+        super().__init__()
+        self.dim = hidden_dim
+        self.num_heads = num_heads
+        self.head_dim = attention_dim // num_heads
+        self.q = nn.Linear(hidden_dim, attention_dim)
+        self.k = nn.Linear(hidden_dim, attention_dim)
+        self.v = nn.Linear(hidden_dim, attention_dim)
+        self.o = nn.Linear(attention_dim, hidden_dim)
+        self.norm_q = WanRMSNorm(attention_dim, eps=eps)
+        self.norm_k = WanRMSNorm(attention_dim, eps=eps)
+
+
+class WanVideoDiT(WanModel):
+    def __init__(
+        self,
+        hidden_dim: int,
+        in_dim: int,
+        ffn_dim: int,
+        out_dim: int,
+        text_dim: int,
+        freq_dim: int,
+        eps: float,
+        patch_size: tuple[int, int, int],
+        num_heads: int,
+        attn_head_dim: int,
+        num_layers: int,
+        has_image_input: bool = False,
+        has_image_pos_emb: bool = False,
+        has_ref_conv: bool = False,
+        add_control_adapter: bool = False,
+        in_dim_control_adapter: int = 24,
+        seperated_timestep: bool = False,
+        require_vae_embedding: bool = False,
+        require_clip_embedding: bool = False,
+        fuse_vae_embedding_in_latents: bool = True,
+        action_conditioned: bool = False,
+        action_dim: int = 7,
+        action_group_causal_mask_mode="causal",
+        video_attention_mask_mode: str = "bidirectional",
+        use_gradient_checkpointing: bool = False,
+        fp32_attention: bool = True,
+    ):
+        del in_dim_control_adapter
+        if has_image_input:
+            raise ValueError("FastWAM currently expects Wan2.2 TI2V latents with fused image conditioning.")
+        if has_image_pos_emb:
+            raise ValueError("FastWAM does not support extra image positional embeddings in WanVideoDiT.")
+        if has_ref_conv:
+            raise ValueError("FastWAM does not support reference convolutions in WanVideoDiT.")
+        if add_control_adapter:
+            raise ValueError("FastWAM does not support control adapters in WanVideoDiT.")
+        if require_clip_embedding:
+            raise ValueError("FastWAM does not support CLIP embedding conditioning in WanVideoDiT.")
+        if require_vae_embedding or not fuse_vae_embedding_in_latents:
+            raise ValueError("FastWAM expects VAE conditioning to be fused in latents.")
+        if attn_head_dim != hidden_dim // num_heads:
+            raise ValueError(
+                "`attn_head_dim` must match the upstream Wan head dimension `hidden_dim // num_heads`; "
+                f"got {attn_head_dim} vs {hidden_dim // num_heads}."
+            )
+
+        super().__init__(
+            model_type="ti2v",
+            patch_size=patch_size,
+            text_len=512,
+            in_dim=in_dim,
+            dim=hidden_dim,
+            ffn_dim=ffn_dim,
+            freq_dim=freq_dim,
+            text_dim=text_dim,
+            out_dim=out_dim,
+            num_heads=num_heads,
+            num_layers=num_layers,
+            qk_norm=True,
+            cross_attn_norm=True,
+            eps=eps,
+        )
+        self.blocks = torch.nn.ModuleList(
+            [
+                FastWAMAttentionBlock(
+                    hidden_dim=hidden_dim,
+                    attn_head_dim=attn_head_dim,
+                    num_heads=num_heads,
+                    ffn_dim=ffn_dim,
+                    eps=eps,
+                    fp32_attention=fp32_attention,
+                )
+                for _ in range(num_layers)
+            ]
+        )
+        self.init_weights()
+
+        self.hidden_dim = hidden_dim
+        self.attn_head_dim = attn_head_dim
+        self.seperated_timestep = seperated_timestep
+        self.fuse_vae_embedding_in_latents = fuse_vae_embedding_in_latents
+        self.video_attention_mask_mode = str(video_attention_mask_mode)
+        self.action_conditioned = action_conditioned
+        self.action_dim = action_dim
+        self.fp32_attention = bool(fp32_attention)
+
+        if self.action_conditioned:
+            self.action_embedding = torch.nn.Linear(action_dim, hidden_dim)
+            self.action_group_causal_mask_mode = action_group_causal_mask_mode
+
+        self.use_gradient_checkpointing = use_gradient_checkpointing
+        if self.use_gradient_checkpointing:
+            logger.info(
+                "Using gradient checkpointing for DiT blocks. This will save memory but use more computation."
+            )
+
+    def patchify(self, x: torch.Tensor):
+        return self.patch_embedding(x)
+
+    def _validate_forward_inputs(
+        self,
+        x: torch.Tensor,
+        timestep: torch.Tensor,
+        context: torch.Tensor,
+        context_mask: torch.Tensor | None,
+        action: torch.Tensor | None,
+    ) -> tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
+        if x.ndim != 5:
+            raise ValueError(f"`latents` must be 5D [B, C, T, H, W], got shape {tuple(x.shape)}")
+        num_latent_frames = x.shape[2]
+        if context.ndim != 3:
+            raise ValueError(f"`context` must be 3D [B, L, D], got shape {tuple(context.shape)}")
+        if timestep.ndim != 1:
+            raise ValueError(f"`timestep` must be 1D [B] or [1], got shape {tuple(timestep.shape)}")
+        if self.action_conditioned:
+            allow_text_only_single_frame = num_latent_frames == 1 and action is None
+            if not allow_text_only_single_frame:
+                if action is None:
+                    raise ValueError("Action input is required for action-conditioned model.")
+                if action.ndim != 3:
+                    raise ValueError(
+                        f"`action` must be 3D [B, action_horizon, action_dim], got shape {tuple(action.shape)}"
+                    )
+                if action.shape[2] != self.action_dim:
+                    raise ValueError(
+                        f"`action` last dimension must be {self.action_dim}, got {action.shape[2]}"
+                    )
+                if num_latent_frames <= 1:
+                    raise ValueError(
+                        f"video length must be > 1 for action-conditioned model, got {num_latent_frames}"
+                    )
+                if action.shape[1] % (num_latent_frames - 1) != 0:
+                    raise ValueError(
+                        "action horizon must be divisible by (num_latent_frames - 1), "
+                        f"got action_horizon={action.shape[1]}"
+                    )
+        if context_mask is None:
+            context_mask = torch.ones(
+                (context.shape[0], context.shape[1]), dtype=torch.bool, device=context.device
+            )
+        else:
+            if context_mask.ndim != 2:
+                raise ValueError(f"`context_mask` must be 2D [B, L], got shape {tuple(context_mask.shape)}")
+            if context_mask.shape[0] != context.shape[0] or context_mask.shape[1] != context.shape[1]:
+                raise ValueError(
+                    "`context_mask` shape must match `context` shape [B, L], "
+                    f"got {tuple(context_mask.shape)} vs {tuple(context.shape)}"
+                )
+
+        batch_size = x.shape[0]
+        if batch_size != context.shape[0]:
+            if not self.training and batch_size == 1:
+                x = x.expand(context.shape[0], -1, -1, -1, -1)
+                batch_size = context.shape[0]
+            else:
+                raise ValueError(
+                    f"Batch mismatch between latents and context: {batch_size} vs {context.shape[0]}."
+                )
+
+        if timestep.shape[0] not in (1, batch_size):
+            raise ValueError(
+                f"`timestep` length must be 1 or batch_size({batch_size}), got {timestep.shape[0]}"
+            )
+        if timestep.shape[0] == 1 and batch_size > 1:
+            if self.training:
+                raise ValueError("During training, timestep length must match batch_size.")
+            timestep = timestep.expand(batch_size)
+        return x, timestep, context_mask
+
+    def build_video_to_video_mask(
+        self,
+        video_seq_len: int,
+        video_tokens_per_frame: int,
+        device: torch.device,
+    ) -> torch.Tensor:
+        if video_seq_len <= 0:
+            raise ValueError(f"`video_seq_len` must be positive, got {video_seq_len}")
+        if video_tokens_per_frame <= 0:
+            raise ValueError(f"`video_tokens_per_frame` must be positive, got {video_tokens_per_frame}")
+
+        if self.video_attention_mask_mode == "bidirectional":
+            return torch.ones((video_seq_len, video_seq_len), dtype=torch.bool, device=device)
+
+        if self.video_attention_mask_mode == "per_frame_causal":
+            if video_seq_len % video_tokens_per_frame != 0:
+                raise ValueError(
+                    "`video_seq_len` must be divisible by `video_tokens_per_frame` in `per_frame_causal` mode, "
+                    f"got {video_seq_len} and {video_tokens_per_frame}"
+                )
+            num_video_frames = video_seq_len // video_tokens_per_frame
+            frame_causal = torch.tril(
+                torch.ones((num_video_frames, num_video_frames), dtype=torch.bool, device=device)
+            )
+            return frame_causal.repeat_interleave(video_tokens_per_frame, dim=0).repeat_interleave(
+                video_tokens_per_frame, dim=1
+            )
+
+        if self.video_attention_mask_mode == "first_frame_causal":
+            video_mask = torch.ones((video_seq_len, video_seq_len), dtype=torch.bool, device=device)
+            first_frame_tokens = min(video_tokens_per_frame, video_seq_len)
+            video_mask[:first_frame_tokens, first_frame_tokens:] = False
+            return video_mask
+
+        raise ValueError(f"Unsupported video attention mask mode: {self.video_attention_mask_mode}")
+
+    def pre_dit(
+        self,
+        x: torch.Tensor,
+        timestep: torch.Tensor,
+        context: torch.Tensor,
+        context_mask: torch.Tensor | None = None,
+        action: torch.Tensor | None = None,
+        fuse_vae_embedding_in_latents: bool = False,
+    ) -> dict[str, Any]:
+        x, timestep, context_mask = self._validate_forward_inputs(
+            x=x,
+            timestep=timestep,
+            context=context,
+            context_mask=context_mask,
+            action=action,
+        )
+        model_dtype = self.patch_embedding.weight.dtype
+        x = x.to(dtype=model_dtype)
+        context = context.to(dtype=model_dtype)
+        if action is not None:
+            action = action.to(dtype=model_dtype)
+
+        batch_size = x.shape[0]
+        patch_h = int(self.patch_size[1])
+        patch_w = int(self.patch_size[2])
+        if x.shape[3] % patch_h != 0 or x.shape[4] % patch_w != 0:
+            raise ValueError(
+                "Latent spatial shape must be divisible by DiT patch size, "
+                f"got HxW=({x.shape[3]}, {x.shape[4]}), patch=({patch_h}, {patch_w})"
+            )
+        tokens_per_frame = (x.shape[3] // patch_h) * (x.shape[4] // patch_w)
+
+        if not (self.seperated_timestep and fuse_vae_embedding_in_latents):
+            raise NotImplementedError(
+                "FastWAM currently requires separated timesteps with fused VAE latents."
+            )
+
+        token_timesteps = torch.ones(
+            (batch_size, x.shape[2], tokens_per_frame),
+            dtype=model_dtype,
+            device=timestep.device,
+        ) * timestep.to(dtype=model_dtype).view(batch_size, 1, 1)
+        token_timesteps[:, 0, :] = 0
+        token_timesteps = token_timesteps.reshape(batch_size, -1)
+        # Wan keeps the time embedding in fp32: the AdaLN modulation in the vendored
+        # Head/Block asserts e.dtype == float32 (numerical stability of the scale/shift).
+        # Upstream guarantees this via an fp32 autocast region, so it holds even when the
+        # model runs in bf16. Mirror that here, then cast the per-block modulation back to
+        # model_dtype so the bf16 attention blocks are not upcast to fp32.
+        with torch.amp.autocast("cuda", dtype=torch.float32):
+            token_t_emb = sinusoidal_embedding_1d(self.freq_dim, token_timesteps.reshape(-1)).float()
+            t = self.time_embedding(token_t_emb).reshape(batch_size, -1, self.hidden_dim)
+            t_mod = self.time_projection(t).unflatten(2, (6, self.hidden_dim))
+        t_mod = t_mod.to(dtype=model_dtype)
+
+        x = self.patchify(x)
+        f, h, w = x.shape[2:]
+
+        context = self.text_embedding(context)
+        context_len = context.shape[1]
+        if self.action_conditioned and action is not None:
+            action_len = action.shape[1]
+            action_emb = self.action_embedding(action)
+            action_pos_embed = sinusoidal_embedding_1d(
+                self.hidden_dim, torch.arange(action_len, device=action_emb.device)
+            ).to(dtype=action_emb.dtype)
+            action_emb = action_emb + action_pos_embed.unsqueeze(0)
+            context = torch.cat([context, action_emb], dim=1)
+
+            num_temporal_groups = f - 1
+            if num_temporal_groups <= 0:
+                raise ValueError(
+                    "Action-conditioned context mask requires at least 2 latent frames when `action` is provided."
+                )
+            if action_emb.shape[1] % num_temporal_groups != 0:
+                raise ValueError(
+                    f"Action embedding length {action_emb.shape[1]} must be divisible by "
+                    f"number of temporal groups {num_temporal_groups}"
+                )
+            action_group_mask = create_group_causal_attn_mask(
+                num_temporal_groups=num_temporal_groups,
+                num_query_per_group=tokens_per_frame,
+                num_key_per_group=action_len // num_temporal_groups,
+                mode=self.action_group_causal_mask_mode,
+            ).to(context.device)
+
+            seq_len = f * h * w
+            final_context_mask = torch.zeros(
+                (batch_size, seq_len, context.shape[1]), dtype=torch.bool, device=context.device
+            )
+            final_context_mask[:, :, :context_len] = context_mask.unsqueeze(1).expand(-1, seq_len, -1)
+            final_context_mask[:, tokens_per_frame:, context_len:] = action_group_mask.unsqueeze(0).expand(
+                batch_size, -1, -1
+            )
+            context_mask = final_context_mask
+        elif self.action_conditioned and action is None:
+            if f != 1:
+                raise ValueError(
+                    "Action-conditioned model requires `action` unless running single-frame text-only mode "
+                    "with num_latent_frames=1."
+                )
+            context_mask = context_mask.unsqueeze(1).expand(-1, f * h * w, -1)
+        else:
+            context_mask = context_mask.unsqueeze(1).expand(-1, f * h * w, -1)
+
+        x_tokens = rearrange(x, "b c f h w -> b (f h w) c").contiguous()
+        grid_sizes = torch.tensor([[f, h, w]] * batch_size, dtype=torch.long, device=x_tokens.device)
+        freqs = {"grid_sizes": grid_sizes, "freqs": self.freqs.to(x_tokens.device)}
+
+        return {
+            "tokens": x_tokens,
+            "freqs": freqs,
+            "t": t,
+            "t_mod": t_mod,
+            "context": context,
+            "context_mask": context_mask,
+            "meta": {
+                "grid_sizes": grid_sizes,
+                "tokens_per_frame": tokens_per_frame,
+                "batch_size": batch_size,
+            },
+        }
+
+    def post_dit(self, x_tokens: torch.Tensor, pre_state: dict[str, Any]) -> torch.Tensor:
+        x = self.head(x_tokens, pre_state["t"])
+        return torch.stack(super().unpatchify(x, pre_state["meta"]["grid_sizes"]))
+
+    def forward(
+        self,
+        x: torch.Tensor,
+        timestep: torch.Tensor,
+        context: torch.Tensor,
+        context_mask: torch.Tensor | None = None,
+        action: torch.Tensor | None = None,
+        fuse_vae_embedding_in_latents: bool = False,
+    ):
+        pre_state = self.pre_dit(
+            x=x,
+            timestep=timestep,
+            context=context,
+            context_mask=context_mask,
+            action=action,
+            fuse_vae_embedding_in_latents=fuse_vae_embedding_in_latents,
+        )
+        x_tokens = pre_state["tokens"]
+        context_emb = pre_state["context"]
+        t_mod = pre_state["t_mod"]
+        freqs = pre_state["freqs"]
+        context_attn_mask = pre_state["context_mask"]
+        self_attn_mask = (
+            self.build_video_to_video_mask(
+                video_seq_len=x_tokens.shape[1],
+                video_tokens_per_frame=int(pre_state["meta"]["tokens_per_frame"]),
+                device=x_tokens.device,
+            )
+            if self.video_attention_mask_mode != "bidirectional"
+            else None
+        )
+
+        for block in self.blocks:
+            if self.use_gradient_checkpointing:
+                x_tokens = gradient_checkpoint_forward(
+                    block,
+                    self.use_gradient_checkpointing,
+                    x_tokens,
+                    context_emb,
+                    t_mod,
+                    freqs,
+                    context_mask=context_attn_mask,
+                    self_attn_mask=self_attn_mask,
+                )
+            else:
+                x_tokens = block(
+                    x_tokens,
+                    context_emb,
+                    t_mod,
+                    freqs,
+                    context_mask=context_attn_mask,
+                    self_attn_mask=self_attn_mask,
+                )
+
+        return self.post_dit(x_tokens, pre_state)

src/lerobot/policies/molmoact2/README.md

@@ -1 +1 @@
-../../../../docs/source/policy_molmoact2_README.md
+../../../../docs/source/molmoact2.mdx

src/lerobot/policies/molmoact2/__init__.py

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-
 # Copyright 2026 The Allen Institute for Artificial Intelligence and The HuggingFace Inc. team. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");

src/lerobot/policies/molmoact2/configuration_molmoact2.py

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-
 # Copyright 2026 The Allen Institute for Artificial Intelligence and The HuggingFace Inc. team. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -16,16 +14,9 @@
 
 from __future__ import annotations
 
-import json
-import math
-import os
-from contextlib import suppress
 from dataclasses import dataclass, field
-from pathlib import Path
 from typing import Any
 
-from huggingface_hub import snapshot_download
-
 from lerobot.configs import FeatureType, NormalizationMode, PolicyFeature, PreTrainedConfig
 from lerobot.optim import (
     AdamWConfig,
@@ -37,146 +28,6 @@ from lerobot.utils.constants import ACTION, OBS_STATE
 
 from ..rtc.configuration_rtc import RTCConfig
 
-MOLMOACT2_DEFAULT_NUM_IMAGES = 2
-MOLMOACT2_IMAGE_TOKENS_PER_IMAGE = 196
-MOLMOACT2_FIXED_PROMPT_TOKEN_BUDGET = 80
-MOLMOACT2_TASK_TOKEN_BUDGET = 32
-MOLMOACT2_SEQUENCE_LENGTH_MARGIN = 32
-MOLMOACT2_SEQUENCE_LENGTH_MULTIPLE = 64
-MOLMOACT2_DISCRETE_ACTION_WRAPPER_TOKENS = 4
-MOLMOACT2_MIN_DISCRETE_ACTION_TOKENS_PER_STEP = 6
-MOLMOACT2_DISCRETE_ACTION_TOKENS_PER_DIM = 0.95
-
-
-def _hf_token() -> str | None:
-    return os.environ.get("HF_TOKEN") or os.environ.get("HF_ACCESS_TOKEN")
-
-
-def _resolve_checkpoint_location(
-    checkpoint_path: str,
-    *,
-    revision: str | None = None,
-    force_download: bool = False,
-) -> str:
-    checkpoint_path = str(checkpoint_path or "").strip()
-    if not checkpoint_path:
-        raise ValueError("MolmoAct2 policy requires `checkpoint_path`.")
-    local_path = Path(checkpoint_path).expanduser()
-    if local_path.exists():
-        return str(local_path)
-    return snapshot_download(
-        repo_id=checkpoint_path,
-        repo_type="model",
-        revision=revision,
-        force_download=force_download,
-        ignore_patterns=["*.py", "*.pyc", "__pycache__/*"],
-        token=_hf_token(),
-    )
-
-
-def _load_hf_norm_metadata_for_tag(
-    checkpoint_path: str,
-    *,
-    revision: str | None,
-    force_download: bool,
-    norm_tag: str | None,
-) -> dict[str, Any]:
-    norm_tag = str(norm_tag or "").strip()
-    if not norm_tag:
-        return {}
-    checkpoint_location = Path(
-        _resolve_checkpoint_location(
-            checkpoint_path,
-            revision=revision,
-            force_download=force_download,
-        )
-    )
-    norm_stats_filename = "norm_stats.json"
-    config_path = checkpoint_location / "config.json"
-    if config_path.exists():
-        with suppress(OSError, json.JSONDecodeError):
-            norm_stats_filename = str(
-                json.loads(config_path.read_text()).get("norm_stats_filename") or norm_stats_filename
-            )
-    stats_path = checkpoint_location / norm_stats_filename
-    if not stats_path.exists():
-        raise FileNotFoundError(
-            f"MolmoAct2 HF checkpoint is missing {norm_stats_filename!r}; cannot resolve norm_tag={norm_tag!r}."
-        )
-    payload = json.loads(stats_path.read_text())
-    metadata_by_tag = payload.get("metadata_by_tag")
-    if not isinstance(metadata_by_tag, dict):
-        raise ValueError(f"MolmoAct2 norm stats file {stats_path} has no metadata_by_tag mapping.")
-    metadata = metadata_by_tag.get(norm_tag)
-    if not isinstance(metadata, dict):
-        available = sorted(str(tag) for tag in metadata_by_tag)
-        raise ValueError(f"Unknown MolmoAct2 norm_tag={norm_tag!r}. Available tags: {available}.")
-    return metadata
-
-
-@LRSchedulerConfig.register_subclass("molmoact2_cosine_decay_with_warmup")
-@dataclass
-class MolmoAct2CosineDecayWithWarmupSchedulerConfig(CosineDecayWithWarmupSchedulerConfig):
-    """MolmoAct2-local cosine scheduler with optional decay-step auto-match.
-
-    LeRobot's generic cosine scheduler keeps an explicit integer decay length.
-    For MolmoAct2, leaving num_decay_steps unset means "decay across this run's
-    training steps"; build() is the first point where num_training_steps is known.
-    """
-
-    num_decay_steps: int | None
-
-    def build(self, optimizer, num_training_steps: int):
-        return CosineDecayWithWarmupSchedulerConfig(
-            peak_lr=self.peak_lr,
-            decay_lr=self.decay_lr,
-            num_warmup_steps=self.num_warmup_steps,
-            num_decay_steps=num_training_steps if self.num_decay_steps is None else self.num_decay_steps,
-        ).build(optimizer, num_training_steps=num_training_steps)
-
-
-def _round_up(value: int, multiple: int) -> int:
-    return int(math.ceil(value / multiple) * multiple)
-
-
-def infer_molmoact2_max_sequence_length(
-    *,
-    num_images: int,
-    state_dim: int,
-    action_dim: int,
-    action_horizon: int,
-    include_discrete_action: bool,
-) -> int:
-    """Infer the padded text/image sequence cap from MolmoAct2's fixed token layout."""
-    if num_images < 1:
-        num_images = MOLMOACT2_DEFAULT_NUM_IMAGES
-    if state_dim < 0:
-        state_dim = 0
-    if action_dim < 1:
-        action_dim = 1
-    if action_horizon < 1:
-        action_horizon = 1
-
-    image_tokens = num_images * MOLMOACT2_IMAGE_TOKENS_PER_IMAGE
-    prompt_tokens = (
-        MOLMOACT2_FIXED_PROMPT_TOKEN_BUDGET
-        + MOLMOACT2_TASK_TOKEN_BUDGET
-        + state_dim
-        + MOLMOACT2_SEQUENCE_LENGTH_MARGIN
-    )
-    action_tokens = 0
-    if include_discrete_action:
-        action_tokens_per_step = max(
-            MOLMOACT2_MIN_DISCRETE_ACTION_TOKENS_PER_STEP,
-            math.ceil(action_dim * MOLMOACT2_DISCRETE_ACTION_TOKENS_PER_DIM),
-        )
-        action_tokens = MOLMOACT2_DISCRETE_ACTION_WRAPPER_TOKENS + action_horizon * action_tokens_per_step
-
-    return _round_up(
-        image_tokens + prompt_tokens + action_tokens,
-        MOLMOACT2_SEQUENCE_LENGTH_MULTIPLE,
-    )
-
 
 @PreTrainedConfig.register_subclass("molmoact2")
 @dataclass
@@ -228,6 +79,15 @@ class MolmoAct2Config(PreTrainedConfig):
     eval_seed: int | None = None
     rtc_config: RTCConfig | None = None
 
+    # Joint frame transform for cross-calibration compatibility.
+    # Some MolmoAct2 checkpoints were trained on data using a different joint
+    # convention than the current LeRobot calibration. Set both to apply a
+    # sign/offset correction at runtime (state before model, action after).
+    # See: https://huggingface.co/docs/lerobot/backwardcomp
+    # Default is None (no transform). Both must be set together.
+    joint_signs: list[float] | None = None
+    joint_offsets: list[float] | None = None
+
     # Default is full finetuning with gradients from the action expert flowing into the VLM.
     enable_lora_vlm: bool = False
     lora_rank: int = 64
@@ -255,7 +115,7 @@ class MolmoAct2Config(PreTrainedConfig):
     optimizer_grad_clip_norm: float = 1.0
 
     scheduler_warmup_steps: int = 200
-    scheduler_decay_steps: int | None = None
+    scheduler_decay_steps: int = 100_000
     scheduler_decay_lr: float = 1e-6
 
     normalization_mapping: dict[str, NormalizationMode] = field(
@@ -272,6 +132,10 @@ class MolmoAct2Config(PreTrainedConfig):
 
     def __post_init__(self) -> None:
         super().__post_init__()
+        if (self.joint_signs is None) != (self.joint_offsets is None):
+            raise ValueError("joint_signs and joint_offsets must both be set or both be None.")
+        if self.joint_signs is not None and len(self.joint_signs) != len(self.joint_offsets):
+            raise ValueError("joint_signs and joint_offsets must have the same length.")
         if self.action_mode not in {"continuous", "discrete", "both"}:
             raise ValueError(
                 f"Unsupported action_mode={self.action_mode!r}. "
@@ -333,41 +197,6 @@ class MolmoAct2Config(PreTrainedConfig):
         if self.max_sequence_length is not None and self.max_sequence_length < 1:
             raise ValueError(f"max_sequence_length must be >= 1 or None, got {self.max_sequence_length}.")
 
-    def inferred_max_sequence_length(
-        self,
-        *,
-        num_images: int | None = None,
-        state_dim: int | None = None,
-        action_dim: int | None = None,
-        action_horizon: int | None = None,
-        include_discrete_action: bool | None = None,
-    ) -> int:
-        if self.max_sequence_length is not None:
-            return int(self.max_sequence_length)
-
-        if num_images is None:
-            num_images = len(self.image_keys) or len(self.image_features) or MOLMOACT2_DEFAULT_NUM_IMAGES
-        if state_dim is None:
-            state_feature = self.robot_state_feature
-            state_dim = int(state_feature.shape[0]) if state_feature is not None else 0
-        if action_dim is None:
-            action_feature = self.action_feature
-            action_dim = (
-                int(action_feature.shape[0]) if action_feature is not None else self.expected_max_action_dim
-            )
-        if action_horizon is None:
-            action_horizon = self.chunk_size
-        if include_discrete_action is None:
-            include_discrete_action = self.action_mode in {"discrete", "both"}
-
-        return infer_molmoact2_max_sequence_length(
-            num_images=int(num_images),
-            state_dim=int(state_dim),
-            action_dim=int(action_dim),
-            action_horizon=int(action_horizon),
-            include_discrete_action=bool(include_discrete_action),
-        )
-
     @property
     def observation_delta_indices(self) -> None:
         return None
@@ -390,7 +219,7 @@ class MolmoAct2Config(PreTrainedConfig):
         )
 
     def get_scheduler_preset(self) -> LRSchedulerConfig | None:
-        return MolmoAct2CosineDecayWithWarmupSchedulerConfig(
+        return CosineDecayWithWarmupSchedulerConfig(
             peak_lr=self.optimizer_lr,
             decay_lr=self.scheduler_decay_lr,
             num_warmup_steps=self.scheduler_warmup_steps,
@@ -426,94 +255,3 @@ class MolmoAct2Config(PreTrainedConfig):
                 shape=(self.expected_max_action_dim,),
             )
             self.output_features[ACTION] = action_feature
-
-    def apply_norm_tag_metadata(self) -> None:
-        if not str(self.norm_tag or "").strip():
-            return
-        metadata = _load_hf_norm_metadata_for_tag(
-            self.checkpoint_path,
-            revision=self.checkpoint_revision,
-            force_download=bool(self.checkpoint_force_download),
-            norm_tag=self.norm_tag,
-        )
-        if metadata.get("action_horizon") is not None:
-            self.chunk_size = int(metadata["action_horizon"])
-        if metadata.get("n_action_steps") is not None:
-            self.n_action_steps = int(metadata["n_action_steps"])
-        if not self.setup_type and metadata.get("setup_type") is not None:
-            self.setup_type = str(metadata["setup_type"])
-        if not self.control_mode and metadata.get("control_mode") is not None:
-            self.control_mode = str(metadata["control_mode"])
-
-    def saved_policy_action_mode(self) -> str | None:
-        pretrained_path = getattr(self, "pretrained_path", None)
-        if pretrained_path is None:
-            return None
-        config_path = Path(pretrained_path) / "config.json"
-        if not config_path.exists():
-            return None
-        try:
-            mode = json.loads(config_path.read_text()).get("action_mode")
-        except (OSError, json.JSONDecodeError):
-            return None
-        if mode in {"continuous", "discrete", "both"}:
-            return str(mode)
-        return None
-
-    def training_action_mode(self, saved_policy_action_mode: str | None = None) -> str:
-        return saved_policy_action_mode or self.action_mode
-
-    def validate_inference_action_mode(self, saved_policy_action_mode: str | None = None) -> None:
-        requested_mode = self.inference_action_mode
-        if requested_mode is None:
-            return
-        training_mode = self.training_action_mode(saved_policy_action_mode)
-        if requested_mode == "continuous" and training_mode == "discrete":
-            raise ValueError(
-                "MolmoAct2 checkpoint was trained with action_mode='discrete' and cannot run "
-                "continuous inference."
-            )
-        if requested_mode == "discrete" and training_mode == "continuous":
-            raise ValueError(
-                "MolmoAct2 checkpoint was trained with action_mode='continuous' and cannot run "
-                "discrete inference. Train with action_mode='both' or action_mode='discrete' first."
-            )
-
-    def validate_checkpoint_action_mode(
-        self,
-        checkpoint_action_mode: str,
-        *,
-        has_action_expert: bool,
-    ) -> None:
-        if self.action_mode == "both" and checkpoint_action_mode != "both":
-            raise ValueError(
-                f"action_mode='both' requires checkpoint action_mode='both', got {checkpoint_action_mode!r}."
-            )
-        if self.action_mode == "discrete" and checkpoint_action_mode not in {"discrete", "both"}:
-            raise ValueError(
-                f"action_mode='discrete' requires checkpoint action_mode in {{'discrete', 'both'}}, "
-                f"got {checkpoint_action_mode!r}."
-            )
-        if self.action_mode in {"continuous", "both"} and not has_action_expert:
-            raise ValueError("Continuous MolmoAct2 training requires an action expert checkpoint.")
-
-    def resolve_inference_action_mode(
-        self,
-        requested_mode: str | None,
-        saved_policy_action_mode: str | None = None,
-    ) -> str:
-        training_mode = self.training_action_mode(saved_policy_action_mode)
-        if requested_mode is None:
-            requested_mode = self.inference_action_mode
-        if requested_mode is None:
-            raise ValueError(
-                "MolmoAct2 inference requires `inference_action_mode` to be set explicitly "
-                "to either 'continuous' or 'discrete'."
-            )
-        if requested_mode not in {"continuous", "discrete"}:
-            raise ValueError("MolmoAct2 inference_action_mode must be either 'continuous' or 'discrete'.")
-        if requested_mode == "continuous" and training_mode == "discrete":
-            raise ValueError("MolmoAct2 action_mode='discrete' checkpoint cannot run continuous inference.")
-        if requested_mode == "discrete" and training_mode == "continuous":
-            raise ValueError("MolmoAct2 action_mode='continuous' checkpoint cannot run discrete inference.")
-        return requested_mode

src/lerobot/policies/molmoact2/modeling_molmoact2.py

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-
 # Copyright 2026 The Allen Institute for Artificial Intelligence and The HuggingFace Inc. team. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -14,9 +12,22 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+"""MolmoAct2 policy for LeRobot.
+
+MolmoAct2 is a VLM-based robotics policy from Allen AI that combines a
+Molmo vision-language backbone with a per-layer flow-matching action expert
+for continuous action generation, plus an optional discrete action token
+head. This module wraps the vendored HF model implementation
+(``molmoact2_hf_model/``) into the LeRobot ``PreTrainedPolicy`` interface.
+
+Paper:  https://allenai.org/blog/molmoact2
+Code:   https://github.com/allenai/molmoact2
+"""
+
 from __future__ import annotations
 
 import json
+import logging
 import os
 import types
 from collections import deque
@@ -35,13 +46,58 @@ from lerobot.utils.constants import ACTION
 from lerobot.utils.import_utils import _scipy_available, _transformers_available, require_package
 
 from ..rtc.modeling_rtc import RTCProcessor
-from .configuration_molmoact2 import MolmoAct2Config, _hf_token, _resolve_checkpoint_location
+from .configuration_molmoact2 import MolmoAct2Config
+
+logger = logging.getLogger(__name__)
+
+
+def _hf_token() -> str | None:
+    return os.environ.get("HF_TOKEN") or os.environ.get("HF_ACCESS_TOKEN")
+
+
+def _resolve_checkpoint_location(
+    checkpoint_path: str,
+    *,
+    revision: str | None = None,
+    force_download: bool = False,
+) -> str:
+    """Resolve a checkpoint path to a local directory, downloading from Hub if needed."""
+    checkpoint_path = str(checkpoint_path or "").strip()
+    if not checkpoint_path:
+        raise ValueError("MolmoAct2 policy requires `checkpoint_path`.")
+    from pathlib import Path
+
+    local_path = Path(checkpoint_path).expanduser()
+    if local_path.exists():
+        return str(local_path)
+    from huggingface_hub import snapshot_download
+
+    return snapshot_download(
+        repo_id=checkpoint_path,
+        repo_type="model",
+        revision=revision,
+        force_download=force_download,
+        ignore_patterns=["*.py", "*.pyc", "__pycache__/*"],
+        token=_hf_token(),
+    )
+
+
+def _torch_dtype(dtype: str) -> torch.dtype:
+    """Convert a dtype name string to a torch.dtype."""
+    if dtype == "float32":
+        return torch.float32
+    if dtype == "bfloat16":
+        return torch.bfloat16
+    if dtype == "float16":
+        return torch.float16
+    raise ValueError(f"Unsupported dtype: {dtype}")
+
 
 if TYPE_CHECKING or _transformers_available:
     from transformers.utils import SAFE_WEIGHTS_INDEX_NAME, SAFE_WEIGHTS_NAME
 
-    from .hf_model.configuration_molmoact2 import MolmoAct2Config as HFMolmoAct2Config
-    from .hf_model.modeling_molmoact2 import MolmoAct2ForConditionalGeneration
+    from .molmoact2_hf_model.configuration_molmoact2 import MolmoAct2Config as HFMolmoAct2Config
+    from .molmoact2_hf_model.modeling_molmoact2 import MolmoAct2ForConditionalGeneration
 else:
     SAFE_WEIGHTS_INDEX_NAME = "model.safetensors.index.json"
     SAFE_WEIGHTS_NAME = "model.safetensors"
@@ -49,7 +105,7 @@ else:
     MolmoAct2ForConditionalGeneration = None
 
 if TYPE_CHECKING or (_transformers_available and _scipy_available):
-    from .hf_model.action_tokenizer import UniversalActionProcessor
+    from .molmoact2_hf_model.action_tokenizer import UniversalActionProcessor
 else:
     UniversalActionProcessor = None
 
@@ -70,6 +126,156 @@ _MODEL_INPUT_KEYS = {
 }
 
 
+def _load_hf_norm_metadata_for_tag(
+    checkpoint_path: str,
+    *,
+    revision: str | None,
+    force_download: bool,
+    norm_tag: str | None,
+) -> dict[str, Any]:
+    """Read per-tag metadata from the checkpoint's ``norm_stats.json``."""
+    norm_tag = str(norm_tag or "").strip()
+    if not norm_tag:
+        return {}
+    from contextlib import suppress
+    from pathlib import Path
+
+    checkpoint_location = Path(
+        _resolve_checkpoint_location(
+            checkpoint_path,
+            revision=revision,
+            force_download=force_download,
+        )
+    )
+    norm_stats_filename = "norm_stats.json"
+    config_path = checkpoint_location / "config.json"
+    if config_path.exists():
+        with suppress(OSError, json.JSONDecodeError):
+            norm_stats_filename = str(
+                json.loads(config_path.read_text()).get("norm_stats_filename") or norm_stats_filename
+            )
+    stats_path = checkpoint_location / norm_stats_filename
+    if not stats_path.exists():
+        raise FileNotFoundError(
+            f"MolmoAct2 HF checkpoint is missing {norm_stats_filename!r}; cannot resolve norm_tag={norm_tag!r}."
+        )
+    payload = json.loads(stats_path.read_text())
+    metadata_by_tag = payload.get("metadata_by_tag")
+    if not isinstance(metadata_by_tag, dict):
+        raise ValueError(f"MolmoAct2 norm stats file {stats_path} has no metadata_by_tag mapping.")
+    metadata = metadata_by_tag.get(norm_tag)
+    if not isinstance(metadata, dict):
+        available = sorted(str(tag) for tag in metadata_by_tag)
+        raise ValueError(f"Unknown MolmoAct2 norm_tag={norm_tag!r}. Available tags: {available}.")
+    return metadata
+
+
+def _apply_norm_tag_metadata(config: MolmoAct2Config) -> None:
+    """Populate config fields from the checkpoint's norm-tag metadata."""
+    if not str(config.norm_tag or "").strip():
+        return
+    metadata = _load_hf_norm_metadata_for_tag(
+        config.checkpoint_path,
+        revision=config.checkpoint_revision,
+        force_download=bool(config.checkpoint_force_download),
+        norm_tag=config.norm_tag,
+    )
+    if metadata.get("action_horizon") is not None:
+        config.chunk_size = int(metadata["action_horizon"])
+    if metadata.get("n_action_steps") is not None:
+        config.n_action_steps = int(metadata["n_action_steps"])
+    if not config.setup_type and metadata.get("setup_type") is not None:
+        config.setup_type = str(metadata["setup_type"])
+    if not config.control_mode and metadata.get("control_mode") is not None:
+        config.control_mode = str(metadata["control_mode"])
+
+
+def _saved_policy_action_mode(config: MolmoAct2Config) -> str | None:
+    """Read the action mode from a LeRobot-saved checkpoint's ``config.json``."""
+    from pathlib import Path
+
+    pretrained_path = getattr(config, "pretrained_path", None)
+    if pretrained_path is None:
+        return None
+    config_path = Path(pretrained_path) / "config.json"
+    if not config_path.exists():
+        return None
+    try:
+        mode = json.loads(config_path.read_text()).get("action_mode")
+    except (OSError, json.JSONDecodeError):
+        return None
+    if mode in {"continuous", "discrete", "both"}:
+        return str(mode)
+    return None
+
+
+def _training_action_mode(config: MolmoAct2Config, saved_policy_action_mode: str | None = None) -> str:
+    return saved_policy_action_mode or config.action_mode
+
+
+def _validate_inference_action_mode(
+    config: MolmoAct2Config, saved_policy_action_mode: str | None = None
+) -> None:
+    """Check that the requested inference mode is compatible with the training mode."""
+    requested_mode = config.inference_action_mode
+    if requested_mode is None:
+        return
+    training_mode = _training_action_mode(config, saved_policy_action_mode)
+    if requested_mode == "continuous" and training_mode == "discrete":
+        raise ValueError(
+            "MolmoAct2 checkpoint was trained with action_mode='discrete' and cannot run "
+            "continuous inference."
+        )
+    if requested_mode == "discrete" and training_mode == "continuous":
+        raise ValueError(
+            "MolmoAct2 checkpoint was trained with action_mode='continuous' and cannot run "
+            "discrete inference. Train with action_mode='both' or action_mode='discrete' first."
+        )
+
+
+def _validate_checkpoint_action_mode(
+    config: MolmoAct2Config,
+    checkpoint_action_mode: str,
+    *,
+    has_action_expert: bool,
+) -> None:
+    """Check that the checkpoint's action mode is compatible with the config."""
+    if config.action_mode == "both" and checkpoint_action_mode != "both":
+        raise ValueError(
+            f"action_mode='both' requires checkpoint action_mode='both', got {checkpoint_action_mode!r}."
+        )
+    if config.action_mode == "discrete" and checkpoint_action_mode not in {"discrete", "both"}:
+        raise ValueError(
+            f"action_mode='discrete' requires checkpoint action_mode in {{'discrete', 'both'}}, "
+            f"got {checkpoint_action_mode!r}."
+        )
+    if config.action_mode in {"continuous", "both"} and not has_action_expert:
+        raise ValueError("Continuous MolmoAct2 training requires an action expert checkpoint.")
+
+
+def _resolve_inference_action_mode(
+    config: MolmoAct2Config,
+    requested_mode: str | None,
+    saved_policy_action_mode: str | None = None,
+) -> str:
+    """Resolve the final inference action mode, validating compatibility."""
+    training_mode = _training_action_mode(config, saved_policy_action_mode)
+    if requested_mode is None:
+        requested_mode = config.inference_action_mode
+    if requested_mode is None:
+        raise ValueError(
+            "MolmoAct2 inference requires `inference_action_mode` to be set explicitly "
+            "to either 'continuous' or 'discrete'."
+        )
+    if requested_mode not in {"continuous", "discrete"}:
+        raise ValueError("MolmoAct2 inference_action_mode must be either 'continuous' or 'discrete'.")
+    if requested_mode == "continuous" and training_mode == "discrete":
+        raise ValueError("MolmoAct2 action_mode='discrete' checkpoint cannot run continuous inference.")
+    if requested_mode == "discrete" and training_mode == "continuous":
+        raise ValueError("MolmoAct2 action_mode='continuous' checkpoint cannot run discrete inference.")
+    return requested_mode
+
+
 def _strict_load_safetensors_weights(model: torch.nn.Module, checkpoint_location: str) -> None:
     index_path = os.path.join(checkpoint_location, SAFE_WEIGHTS_INDEX_NAME)
     single_file_path = os.path.join(checkpoint_location, SAFE_WEIGHTS_NAME)
@@ -103,16 +309,6 @@ def _strict_load_safetensors_weights(model: torch.nn.Module, checkpoint_location
     )
 
 
-def _torch_dtype(dtype: str) -> torch.dtype:
-    if dtype == "float32":
-        return torch.float32
-    if dtype == "bfloat16":
-        return torch.bfloat16
-    if dtype == "float16":
-        return torch.float16
-    raise ValueError(f"Unsupported dtype: {dtype}")
-
-
 def _sample_beta_timesteps(
     *,
     batch_size: int,
@@ -136,7 +332,180 @@ def _sample_beta_timesteps(
     return time_offset + scale * samples
 
 
+def _mask_discrete_action_spans(
+    *,
+    input_ids: Tensor,
+    mask: Tensor,
+    start_token_id: int | None,
+    end_token_id: int | None,
+) -> Tensor:
+    if start_token_id is None or end_token_id is None:
+        return mask
+    mask = mask.clone()
+    for batch_idx in range(input_ids.shape[0]):
+        row = input_ids[batch_idx]
+        starts = (row == int(start_token_id)).nonzero(as_tuple=False).flatten().tolist()
+        ends = (row == int(end_token_id)).nonzero(as_tuple=False).flatten().tolist()
+        end_ptr = 0
+        for start in starts:
+            while end_ptr < len(ends) and ends[end_ptr] < start:
+                end_ptr += 1
+            if end_ptr >= len(ends):
+                mask[batch_idx, start:] = False
+                break
+            end = int(ends[end_ptr])
+            mask[batch_idx, start : end + 1] = False
+            end_ptr += 1
+    return mask
+
+
+def _drop_trivial_attention_mask(model_inputs: dict[str, Tensor]) -> dict[str, Tensor]:
+    attention_mask = model_inputs.get("attention_mask")
+    if torch.is_tensor(attention_mask) and bool(attention_mask.to(dtype=torch.bool).all().item()):
+        model_inputs = dict(model_inputs)
+        model_inputs.pop("attention_mask", None)
+    return model_inputs
+
+
+def _expand_mask(mask: Tensor | None, num_flow_timesteps: int) -> Tensor | None:
+    if mask is None:
+        return None
+    return (
+        mask.unsqueeze(1)
+        .expand(-1, num_flow_timesteps, *([-1] * (mask.ndim - 1)))
+        .reshape(mask.shape[0] * num_flow_timesteps, *mask.shape[1:])
+    )
+
+
+def _action_dim_valid_mask(target: Tensor, action_dim_is_pad: Tensor | None) -> Tensor | None:
+    if action_dim_is_pad is None:
+        return None
+    mask = ~action_dim_is_pad.to(device=target.device, dtype=torch.bool)
+    if mask.ndim == 1:
+        mask = mask.unsqueeze(0)
+    if mask.shape[-1] != target.shape[-1]:
+        raise ValueError(
+            f"action_dim_is_pad width {mask.shape[-1]} does not match target width {target.shape[-1]}."
+        )
+    if mask.shape[0] == 1 and target.shape[0] != 1:
+        mask = mask.expand(target.shape[0], -1)
+    if mask.shape[0] != target.shape[0]:
+        raise ValueError(
+            f"action_dim_is_pad batch {mask.shape[0]} does not match target batch {target.shape[0]}."
+        )
+    while mask.ndim < target.ndim:
+        mask = mask.unsqueeze(1)
+    return mask
+
+
+def _mask_action_dim_tensor(tensor: Tensor, action_dim_is_pad: Tensor | None) -> Tensor:
+    if action_dim_is_pad is None:
+        return tensor
+    valid_mask = _action_dim_valid_mask(tensor, action_dim_is_pad)
+    if valid_mask is None:
+        return tensor
+    return tensor.masked_fill(~valid_mask, 0)
+
+
+def _apply_action_dim_padding_mask(loss: Tensor, action_dim_is_pad: Tensor | None) -> Tensor:
+    valid_mask = _action_dim_valid_mask(loss, action_dim_is_pad)
+    if valid_mask is None:
+        return loss
+    valid = valid_mask.to(dtype=loss.dtype)
+    denom = valid.sum(dim=-1).clamp_min(1.0)
+    return (loss * valid).sum(dim=-1) / denom
+
+
+def _apply_action_chunk_padding_mask(loss: Tensor, action_horizon_is_pad: Tensor | None) -> Tensor:
+    if action_horizon_is_pad is None:
+        return loss
+    valid_action = (
+        (~action_horizon_is_pad.to(device=loss.device, dtype=torch.bool)).unsqueeze(1).unsqueeze(-1)
+    )
+    return loss * valid_action
+
+
+def _combine_rollout_seeds(first_seed: int, batch_size: int) -> int:
+    seed = 0
+    for idx in range(batch_size):
+        seed = (seed + (idx + 1) * (first_seed + idx)) % (2**63 - 1)
+    return seed
+
+
+def _rollout_task_signature(batch: dict[str, Any]) -> tuple[Any, ...] | None:
+    task = batch.get("task")
+    if task is None:
+        task = batch.get("observation.language")
+    if task is None:
+        return None
+    if isinstance(task, str):
+        return (task,)
+    if isinstance(task, (list, tuple)):
+        return tuple(str(item) for item in task)
+    return (str(task),)
+
+
+def _extract_discrete_token_bins(
+    generated_ids: list[int],
+    start_token_id: int,
+    end_token_id: int,
+    token_id_to_bin: dict[int, int],
+) -> list[int]:
+    start_idx = None
+    end_idx = None
+    for idx, token_id in enumerate(generated_ids):
+        if token_id == start_token_id:
+            start_idx = idx
+            break
+    if start_idx is not None:
+        for idx in range(start_idx + 1, len(generated_ids)):
+            if generated_ids[idx] == end_token_id:
+                end_idx = idx
+                break
+    span_start = 0 if start_idx is None else start_idx + 1
+    span_end = len(generated_ids) if end_idx is None else end_idx
+    return [
+        int(token_id_to_bin[token_id])
+        for token_id in generated_ids[span_start:span_end]
+        if token_id in token_id_to_bin
+    ]
+
+
+def _weighted_mean(values: Tensor, weights: Tensor | None) -> Tensor:
+    if weights is None:
+        return values.mean()
+    weights = weights.to(device=values.device, dtype=values.dtype)
+    return torch.dot(values, weights) / weights.sum().clamp_min(1.0)
+
+
+def _weighted_per_example(
+    values: Tensor,
+    weights: Tensor | None,
+    example_indices: Tensor,
+    batch_size: int,
+) -> Tensor:
+    values = values.float()
+    if weights is None:
+        weights = torch.ones_like(values)
+    else:
+        weights = weights.to(device=values.device, dtype=values.dtype)
+    loss_sum = torch.zeros(batch_size, device=values.device, dtype=torch.float32)
+    weight_sum = torch.zeros(batch_size, device=values.device, dtype=torch.float32)
+    loss_sum.scatter_add_(0, example_indices, values * weights)
+    weight_sum.scatter_add_(0, example_indices, weights)
+    global_weight_sum = weight_sum.sum().clamp_min(1.0)
+    return loss_sum * float(batch_size) / global_weight_sum
+
+
 class MolmoAct2Policy(PreTrainedPolicy):
+    """MolmoAct2 policy wrapping the vendored HF model for LeRobot.
+
+    Supports three training modes via ``config.action_mode``:
+    ``"continuous"`` (flow-matching only), ``"discrete"`` (autoregressive
+    token prediction only), or ``"both"`` (joint loss). At inference,
+    ``config.inference_action_mode`` selects which head generates actions.
+    """
+
     config_class = MolmoAct2Config
     name = "molmoact2"
 
@@ -149,10 +518,10 @@ class MolmoAct2Policy(PreTrainedPolicy):
         **kwargs,
     ):
         super().__init__(config, *inputs, **kwargs)
-        self.config.apply_norm_tag_metadata()
+        _apply_norm_tag_metadata(self.config)
         self.config.validate_features()
         del inputs, kwargs, dataset_stats, dataset_meta
-        self._checkpoint_action_mode = self.config.saved_policy_action_mode()
+        self._checkpoint_action_mode = _saved_policy_action_mode(self.config)
         self._action_queue: deque[Tensor] = deque(maxlen=self.config.n_action_steps)
         self._rollout_action_generator: torch.Generator | None = None
         self._rollout_task_key: tuple[Any, ...] | None = None
@@ -160,7 +529,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
         self.rtc_processor: RTCProcessor | None = None
         self.action_tokenizer: Any | None = None
         self._load_hf_model()
-        self.config.validate_inference_action_mode(self._checkpoint_action_mode)
+        _validate_inference_action_mode(self.config, self._checkpoint_action_mode)
         if self.config.enable_lora_vlm:
             self._apply_lora_adapters()
         self.init_rtc_processor()
@@ -212,7 +581,8 @@ class MolmoAct2Policy(PreTrainedPolicy):
                 "`policy.checkpoint_force_download=true` after the updated files are pushed."
             )
         checkpoint_action_mode = str(self.model.config.action_mode)
-        self.config.validate_checkpoint_action_mode(
+        _validate_checkpoint_action_mode(
+            self.config,
             checkpoint_action_mode,
             has_action_expert=bool(getattr(self.model.config, "add_action_expert", False)),
         )
@@ -226,6 +596,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
         self.train(self.training)
 
     def reset(self) -> None:
+        """Clear the action queue and rollout generator between episodes."""
         self._action_queue = deque(maxlen=self.config.n_action_steps)
         self._rollout_action_generator = None
 
@@ -334,6 +705,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
             param.requires_grad = False
 
     def get_optim_params(self) -> list[dict[str, Any]]:
+        """Return optimizer param groups with per-component learning rates."""
         vit_params: list[Tensor] = []
         connector_params: list[Tensor] = []
         action_expert_params: list[Tensor] = []
@@ -419,33 +791,6 @@ class MolmoAct2Policy(PreTrainedPolicy):
                 return int(value)
         raise RuntimeError("MolmoAct2 could not resolve an action generation horizon.")
 
-    @staticmethod
-    def _mask_discrete_action_spans(
-        *,
-        input_ids: Tensor,
-        mask: Tensor,
-        start_token_id: int | None,
-        end_token_id: int | None,
-    ) -> Tensor:
-        if start_token_id is None or end_token_id is None:
-            return mask
-        mask = mask.clone()
-        for batch_idx in range(input_ids.shape[0]):
-            row = input_ids[batch_idx]
-            starts = (row == int(start_token_id)).nonzero(as_tuple=False).flatten().tolist()
-            ends = (row == int(end_token_id)).nonzero(as_tuple=False).flatten().tolist()
-            end_ptr = 0
-            for start in starts:
-                while end_ptr < len(ends) and ends[end_ptr] < start:
-                    end_ptr += 1
-                if end_ptr >= len(ends):
-                    mask[batch_idx, start:] = False
-                    break
-                end = int(ends[end_ptr])
-                mask[batch_idx, start : end + 1] = False
-                end_ptr += 1
-        return mask
-
     def _encoder_attention_mask_for_action_expert(
         self,
         *,
@@ -470,21 +815,13 @@ class MolmoAct2Policy(PreTrainedPolicy):
         eos_token_id = getattr(self.model.config, "eos_token_id", None)
         if eos_token_id is not None:
             mask &= input_ids != int(eos_token_id)
-        return self._mask_discrete_action_spans(
+        return _mask_discrete_action_spans(
             input_ids=input_ids,
             mask=mask,
             start_token_id=getattr(self.model.config, "action_start_token_id", None),
             end_token_id=getattr(self.model.config, "action_end_token_id", None),
         )
 
-    @staticmethod
-    def _drop_trivial_attention_mask(model_inputs: dict[str, Tensor]) -> dict[str, Tensor]:
-        attention_mask = model_inputs.get("attention_mask")
-        if torch.is_tensor(attention_mask) and bool(attention_mask.to(dtype=torch.bool).all().item()):
-            model_inputs = dict(model_inputs)
-            model_inputs.pop("attention_mask", None)
-        return model_inputs
-
     def _load_discrete_action_tokenizer(self) -> Any:
         if self.action_tokenizer is None:
             require_package("transformers", extra="molmoact2")
@@ -498,27 +835,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
         return self.action_tokenizer
 
     def _resolve_inference_action_mode(self, requested_mode: str | None) -> str:
-        return self.config.resolve_inference_action_mode(requested_mode, self._checkpoint_action_mode)
-
-    @staticmethod
-    def _combine_rollout_seeds(first_seed: int, batch_size: int) -> int:
-        seed = 0
-        for idx in range(batch_size):
-            seed = (seed + (idx + 1) * (first_seed + idx)) % (2**63 - 1)
-        return seed
-
-    @staticmethod
-    def _rollout_task_signature(batch: dict[str, Any]) -> tuple[Any, ...] | None:
-        task = batch.get("task")
-        if task is None:
-            task = batch.get("observation.language")
-        if task is None:
-            return None
-        if isinstance(task, str):
-            return (task,)
-        if isinstance(task, (list, tuple)):
-            return tuple(str(item) for item in task)
-        return (str(task),)
+        return _resolve_inference_action_mode(self.config, requested_mode, self._checkpoint_action_mode)
 
     def _rollout_generator_for_inputs(
         self,
@@ -532,7 +849,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
         if self._rollout_action_generator is not None:
             return self._rollout_action_generator
 
-        task_signature = self._rollout_task_signature(batch)
+        task_signature = _rollout_task_signature(batch)
         if task_signature != self._rollout_task_key:
             self._rollout_task_key = task_signature
             self._rollout_index_for_task = 0
@@ -545,72 +862,10 @@ class MolmoAct2Policy(PreTrainedPolicy):
             device if device.type == "cuda" and torch.cuda.is_available() else torch.device("cpu")
         )
         generator = torch.Generator(device=generator_device)
-        generator.manual_seed(self._combine_rollout_seeds(first_seed, batch_size))
+        generator.manual_seed(_combine_rollout_seeds(first_seed, batch_size))
         self._rollout_action_generator = generator
         return generator
 
-    @staticmethod
-    def _expand_mask(mask: Tensor | None, num_flow_timesteps: int) -> Tensor | None:
-        if mask is None:
-            return None
-        return (
-            mask.unsqueeze(1)
-            .expand(-1, num_flow_timesteps, *([-1] * (mask.ndim - 1)))
-            .reshape(mask.shape[0] * num_flow_timesteps, *mask.shape[1:])
-        )
-
-    @staticmethod
-    def _action_dim_valid_mask(target: Tensor, action_dim_is_pad: Tensor | None) -> Tensor | None:
-        if action_dim_is_pad is None:
-            return None
-        mask = ~action_dim_is_pad.to(device=target.device, dtype=torch.bool)
-        if mask.ndim == 1:
-            mask = mask.unsqueeze(0)
-        if mask.shape[-1] != target.shape[-1]:
-            raise ValueError(
-                f"action_dim_is_pad width {mask.shape[-1]} does not match target width {target.shape[-1]}."
-            )
-        if mask.shape[0] == 1 and target.shape[0] != 1:
-            mask = mask.expand(target.shape[0], -1)
-        if mask.shape[0] != target.shape[0]:
-            raise ValueError(
-                f"action_dim_is_pad batch {mask.shape[0]} does not match target batch {target.shape[0]}."
-            )
-        while mask.ndim < target.ndim:
-            mask = mask.unsqueeze(1)
-        return mask
-
-    @classmethod
-    def _mask_action_dim_tensor(cls, tensor: Tensor, action_dim_is_pad: Tensor | None) -> Tensor:
-        if not cls._mask_enabled_static(action_dim_is_pad):
-            return tensor
-        valid_mask = cls._action_dim_valid_mask(tensor, action_dim_is_pad)
-        if valid_mask is None:
-            return tensor
-        return tensor.masked_fill(~valid_mask, 0)
-
-    @staticmethod
-    def _mask_enabled_static(action_dim_is_pad: Tensor | None) -> bool:
-        return action_dim_is_pad is not None
-
-    @classmethod
-    def _apply_action_dim_padding_mask(cls, loss: Tensor, action_dim_is_pad: Tensor | None) -> Tensor:
-        valid_mask = cls._action_dim_valid_mask(loss, action_dim_is_pad)
-        if valid_mask is None:
-            return loss
-        valid = valid_mask.to(dtype=loss.dtype)
-        denom = valid.sum(dim=-1).clamp_min(1.0)
-        return (loss * valid).sum(dim=-1) / denom
-
-    @staticmethod
-    def _apply_action_chunk_padding_mask(loss: Tensor, action_horizon_is_pad: Tensor | None) -> Tensor:
-        if action_horizon_is_pad is None:
-            return loss
-        valid_action = (
-            (~action_horizon_is_pad.to(device=loss.device, dtype=torch.bool)).unsqueeze(1).unsqueeze(-1)
-        )
-        return loss * valid_action
-
     def _prepare_flow_matching_tensors(
         self,
         *,
@@ -649,7 +904,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
                 )
 
         if self.config.mask_action_dim_padding:
-            actions = self._mask_action_dim_tensor(actions, action_dim_is_pad)
+            actions = _mask_action_dim_tensor(actions, action_dim_is_pad)
 
         expected_noise_shape = (batch_size, num_flow_timesteps, actions.shape[1], actions.shape[2])
         if noise is None:
@@ -661,7 +916,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
                     f"flow noise must have shape {expected_noise_shape}, got {tuple(noise.shape)}."
                 )
         if self.config.mask_action_dim_padding:
-            noise = self._mask_action_dim_tensor(noise, action_dim_is_pad)
+            noise = _mask_action_dim_tensor(noise, action_dim_is_pad)
 
         t_broadcast = timesteps.view(batch_size, num_flow_timesteps, 1, 1)
         actions_expanded = actions.unsqueeze(1).expand(-1, num_flow_timesteps, -1, -1)
@@ -789,7 +1044,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
         valid_action = None
         if action_attention_mask is not None:
             valid_action = action_attention_mask.to(device=device, dtype=actions.dtype).unsqueeze(-1)
-            valid_action = self._expand_mask(valid_action, num_flow_timesteps)
+            valid_action = _expand_mask(valid_action, num_flow_timesteps)
 
         rope_cache = None
         if len(action_expert.blocks) > 0 and action_expert.blocks[0].self_attn.rope is not None:
@@ -804,14 +1059,14 @@ class MolmoAct2Policy(PreTrainedPolicy):
             batch_size,
             actions.dtype,
         )
-        cross_mask = self._expand_mask(cross_mask, num_flow_timesteps)
+        cross_mask = _expand_mask(cross_mask, num_flow_timesteps)
         self_mask = action_expert._build_self_attention_mask(
             action_attention_mask,
             actions.shape[1],
             device,
             actions.dtype,
         )
-        self_mask = self._expand_mask(self_mask, num_flow_timesteps)
+        self_mask = _expand_mask(self_mask, num_flow_timesteps)
 
         conditioning = self._action_time_conditioning(action_expert, timesteps_flat)
         action_hidden = action_expert.action_embed(xt_flat)
@@ -871,8 +1126,8 @@ class MolmoAct2Policy(PreTrainedPolicy):
             if k_norm is not None:
                 k_ctx = k_norm(k_ctx.transpose(1, 2)).transpose(1, 2)
             if num_flow_timesteps != 1:
-                k_ctx = self._expand_mask(k_ctx, num_flow_timesteps)
-                v_ctx = self._expand_mask(v_ctx, num_flow_timesteps)
+                k_ctx = _expand_mask(k_ctx, num_flow_timesteps)
+                v_ctx = _expand_mask(v_ctx, num_flow_timesteps)
 
             next_action_hidden = action_block(
                 layer_action_hidden,
@@ -912,9 +1167,9 @@ class MolmoAct2Policy(PreTrainedPolicy):
         )
 
         loss = F.mse_loss(pred_velocity, target_velocity, reduction="none")
-        loss = self._apply_action_chunk_padding_mask(loss, batch.get("action_horizon_is_pad"))
+        loss = _apply_action_chunk_padding_mask(loss, batch.get("action_horizon_is_pad"))
         if self.config.mask_action_dim_padding:
-            loss = self._apply_action_dim_padding_mask(loss, batch.get("action_dim_is_pad"))
+            loss = _apply_action_dim_padding_mask(loss, batch.get("action_dim_is_pad"))
         loss = loss.reshape(batch_size, -1).mean(dim=1)
         if reduction == "mean":
             loss = loss.mean()
@@ -933,32 +1188,6 @@ class MolmoAct2Policy(PreTrainedPolicy):
         example_weights[nonempty] = 2.0 / torch.sqrt(token_counts[nonempty])
         return example_weights[:, None].expand_as(valid_positions)[valid_positions].to(dtype=torch.float32)
 
-    @staticmethod
-    def _weighted_mean(values: Tensor, weights: Tensor | None) -> Tensor:
-        if weights is None:
-            return values.mean()
-        weights = weights.to(device=values.device, dtype=values.dtype)
-        return torch.dot(values, weights) / weights.sum().clamp_min(1.0)
-
-    @staticmethod
-    def _weighted_per_example(
-        values: Tensor,
-        weights: Tensor | None,
-        example_indices: Tensor,
-        batch_size: int,
-    ) -> Tensor:
-        values = values.float()
-        if weights is None:
-            weights = torch.ones_like(values)
-        else:
-            weights = weights.to(device=values.device, dtype=values.dtype)
-        loss_sum = torch.zeros(batch_size, device=values.device, dtype=torch.float32)
-        weight_sum = torch.zeros(batch_size, device=values.device, dtype=torch.float32)
-        loss_sum.scatter_add_(0, example_indices, values * weights)
-        weight_sum.scatter_add_(0, example_indices, weights)
-        global_weight_sum = weight_sum.sum().clamp_min(1.0)
-        return loss_sum * float(batch_size) / global_weight_sum
-
     def _discrete_loss_from_backbone_outputs(
         self,
         batch: dict[str, Tensor],
@@ -992,56 +1221,28 @@ class MolmoAct2Policy(PreTrainedPolicy):
         token_weights = self._discrete_token_weights(valid_positions)
         if reduction == "none":
             example_indices = valid_positions.nonzero(as_tuple=False)[:, 0].to(device=hidden_states.device)
-            ce_loss = self._weighted_per_example(
+            ce_loss = _weighted_per_example(
                 token_ce_loss,
                 token_weights,
                 example_indices,
                 int(labels.shape[0]),
             )
         else:
-            ce_loss = self._weighted_mean(token_ce_loss, token_weights)
+            ce_loss = _weighted_mean(token_ce_loss, token_weights)
         if not self.config.softmax_auxiliary_loss:
             return ce_loss, None
 
         if reduction == "none":
-            z_loss = self.config.softmax_auxiliary_loss_scale * self._weighted_per_example(
+            z_loss = self.config.softmax_auxiliary_loss_scale * _weighted_per_example(
                 log_z.pow(2),
                 token_weights,
                 example_indices,
                 int(labels.shape[0]),
             )
         else:
-            z_loss = self.config.softmax_auxiliary_loss_scale * self._weighted_mean(
-                log_z.pow(2), token_weights
-            )
+            z_loss = self.config.softmax_auxiliary_loss_scale * _weighted_mean(log_z.pow(2), token_weights)
         return ce_loss, z_loss
 
-    @staticmethod
-    def _extract_discrete_token_bins(
-        generated_ids: list[int],
-        start_token_id: int,
-        end_token_id: int,
-        token_id_to_bin: dict[int, int],
-    ) -> list[int]:
-        start_idx = None
-        end_idx = None
-        for idx, token_id in enumerate(generated_ids):
-            if token_id == start_token_id:
-                start_idx = idx
-                break
-        if start_idx is not None:
-            for idx in range(start_idx + 1, len(generated_ids)):
-                if generated_ids[idx] == end_token_id:
-                    end_idx = idx
-                    break
-        span_start = 0 if start_idx is None else start_idx + 1
-        span_end = len(generated_ids) if end_idx is None else end_idx
-        return [
-            int(token_id_to_bin[token_id])
-            for token_id in generated_ids[span_start:span_end]
-            if token_id in token_id_to_bin
-        ]
-
     def _action_token_id_to_bin(self) -> dict[int, int]:
         method = getattr(self.model, "_action_token_id_to_bin", None)
         if callable(method):
@@ -1179,7 +1380,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
         chunks: list[Tensor] = []
         for token_row in generated_token_ids:
             generated_ids = [int(token_id) for token_id in token_row.detach().cpu().tolist()]
-            discrete_token_ids = self._extract_discrete_token_bins(
+            discrete_token_ids = _extract_discrete_token_bins(
                 generated_ids,
                 int(self.model.config.action_start_token_id),
                 int(self.model.config.action_end_token_id),
@@ -1218,7 +1419,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
         model_inputs: dict[str, Tensor],
         action_dim: int,
     ) -> Tensor:
-        model_inputs = self._drop_trivial_attention_mask(model_inputs)
+        model_inputs = _drop_trivial_attention_mask(model_inputs)
         max_steps = self._discrete_generation_max_steps()
         static_cache, attention_bias = self._make_discrete_ar_graph_decode_inputs(
             model_inputs,
@@ -1294,7 +1495,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
             generator=generator,
         )
         if self.config.mask_action_dim_padding:
-            trajectory = self._mask_action_dim_tensor(trajectory, action_dim_is_pad)
+            trajectory = _mask_action_dim_tensor(trajectory, action_dim_is_pad)
 
         action_context = action_expert.prepare_context(
             encoder_kv_states=encoder_kv_states,
@@ -1327,7 +1528,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
                     modulation=step_modulation,
                 )
                 if mask_enabled:
-                    velocity = self._mask_action_dim_tensor(velocity, action_dim_is_pad)
+                    velocity = _mask_action_dim_tensor(velocity, action_dim_is_pad)
                 return velocity
 
             if self._rtc_enabled():
@@ -1352,7 +1553,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
 
             trajectory = trajectory + dt * velocity
             if mask_enabled:
-                trajectory = self._mask_action_dim_tensor(trajectory, action_dim_is_pad)
+                trajectory = _mask_action_dim_tensor(trajectory, action_dim_is_pad)
             if self.rtc_processor is not None and self.rtc_processor.is_debug_enabled():
                 self.rtc_processor.track(time=float(flow_timestep[0].item()), x_t=trajectory, v_t=velocity)
 
@@ -1363,6 +1564,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
         batch: dict[str, Tensor],
         reduction: str = "mean",
     ) -> tuple[Tensor, dict[str, Any]]:
+        """Compute training loss (flow-matching and/or discrete token loss)."""
         if reduction not in {"mean", "none"}:
             raise ValueError(f"Unsupported reduction={reduction!r}. Expected 'mean' or 'none'.")
         model_inputs = self._model_inputs(batch)
@@ -1422,6 +1624,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
 
     @torch.no_grad()
     def predict_action_chunk(self, batch: dict[str, Tensor], **kwargs) -> Tensor:
+        """Generate an action chunk via continuous flow matching or discrete AR decoding."""
         if "action_mode" in kwargs:
             raise TypeError(
                 "MolmoAct2 predict_action_chunk got unexpected keyword argument 'action_mode'; "
@@ -1476,6 +1679,7 @@ class MolmoAct2Policy(PreTrainedPolicy):
 
     @torch.no_grad()
     def select_action(self, batch: dict[str, Tensor], **kwargs) -> Tensor:
+        """Pop one action step from the queue, regenerating the chunk when empty."""
         if self._rtc_enabled():
             raise AssertionError("RTC is not supported for select_action, use it with predict_action_chunk")
         self.eval()

src/lerobot/policies/molmoact2/molmoact2_hf_model/__init__.py

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-
 # Copyright 2026 The Allen Institute for Artificial Intelligence and The HuggingFace Inc. team. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -13,5 +11,3 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
-# ruff: noqa

src/lerobot/policies/molmoact2/molmoact2_hf_model/action_tokenizer.py

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-
 # Copyright 2026 The Allen Institute for Artificial Intelligence and The HuggingFace Inc. team. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -14,23 +12,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# ruff: noqa
-
 import logging
-import os
 from pathlib import Path
 from typing import ClassVar
 
 import numpy as np
 from tokenizers import ByteLevelBPETokenizer
 from tokenizers.trainers import BpeTrainer
-from huggingface_hub import snapshot_download
 from transformers import PreTrainedTokenizerFast
 from transformers.processing_utils import ProcessorMixin
 
+from ..modeling_molmoact2 import _hf_token
 
-def _hf_token() -> str | None:
-    return os.environ.get("HF_TOKEN") or os.environ.get("HF_ACCESS_TOKEN")
+logger = logging.getLogger(__name__)
 
 
 def _resolve_tokenizer_location(
@@ -42,6 +36,8 @@ def _resolve_tokenizer_location(
     local_path = Path(str(tokenizer_path)).expanduser()
     if local_path.exists():
         return str(local_path)
+    from huggingface_hub import snapshot_download
+
     return snapshot_download(
         repo_id=str(tokenizer_path),
         repo_type="model",
@@ -134,9 +130,8 @@ class UniversalActionProcessor(ProcessorMixin):
                 ), (
                     f"Decoded DCT coefficients have shape {decoded_dct_coeff.shape}, expected ({self.time_horizon}, {self.action_dim})"
                 )
-            except Exception as e:
-                print(f"Error decoding tokens: {e}")
-                print(f"Tokens: {token}")
+            except Exception:
+                logger.warning("Error decoding tokens: %s", token, exc_info=True)
                 decoded_dct_coeff = np.zeros((self.time_horizon, self.action_dim))
             decoded_actions.append(idct(decoded_dct_coeff / self.scale, axis=0, norm="ortho"))
         return np.stack(decoded_actions)

src/lerobot/policies/molmoact2/molmoact2_hf_model/configuration_molmoact2.py

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-
 # Copyright 2026 The Allen Institute for Artificial Intelligence and The HuggingFace Inc. team. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -14,13 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# ruff: noqa
 
 """
 MolmoAct2 configuration
 """
 
-from typing import Optional, Any
+from typing import Any
 
 from transformers import PretrainedConfig
 from transformers.modeling_rope_utils import rope_config_validation

src/lerobot/policies/molmoact2/molmoact2_hf_model/image_processing_molmoact2.py

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-
 # Copyright 2026 The Allen Institute for Artificial Intelligence and The HuggingFace Inc. team. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -14,33 +12,28 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# ruff: noqa
 
 """Image processor class for MolmoAct2"""
 
-from typing import Optional, Union
-import numpy as np
 import einops
+import numpy as np
 import torch
 import torchvision.transforms
-
+from transformers.feature_extraction_utils import BatchFeature
+from transformers.image_processing_utils import BaseImageProcessor, get_size_dict
+from transformers.image_transforms import convert_to_rgb
 from transformers.image_utils import (
     IMAGENET_STANDARD_MEAN,
     IMAGENET_STANDARD_STD,
     ImageInput,
     PILImageResampling,
     make_flat_list_of_images,
-    valid_images,
     to_numpy_array,
+    valid_images,
 )
-from transformers.image_transforms import convert_to_rgb
 from transformers.processing_utils import ImagesKwargs
-from transformers.image_processing_utils import BaseImageProcessor, get_size_dict
-from transformers.utils import logging
-from transformers.feature_extraction_utils import BatchFeature
 from transformers.utils import TensorType, logging
 
-
 logger = logging.get_logger(__name__)
 
 
@@ -73,8 +66,8 @@ def resize_image(
         )(image)
         resized = torch.clip(resized, 0.0, 1.0).to(dtype)
     else:
-        assert image.dtype == torch.uint8, "SigLIP expects float images or uint8 images, but got {}".format(
-            image.dtype
+        assert image.dtype == torch.uint8, (
+            f"SigLIP expects float images or uint8 images, but got {image.dtype}"
         )
         in_min = 0.0
         in_max = 255.0
@@ -96,7 +89,6 @@ def resize_image(
 def select_tiling(h, w, patch_size, max_num_crops):
     """Divide in image of size [w, h] in up to max_num_patches of size patch_size"""
     original_size = np.stack([h, w])  # [1, 2]
-    original_res = h * w
     tilings = []
     for i in range(1, max_num_crops + 1):
         for j in range(1, max_num_crops + 1):
@@ -406,13 +398,17 @@ class MolmoAct2ImageProcessor(BaseImageProcessor):
         image_std: float | list[float] | None = None,
         do_convert_rgb: bool = True,
         max_crops: int = 8,
-        overlap_margins: list[int] = [4, 4],
+        overlap_margins: list[int] | None = None,
         crop_mode: str = "overlap-and-resize-c2",
         patch_size: int = 14,
-        pooling_size: list[int] = [2, 2],
+        pooling_size: list[int] | None = None,
         **kwargs,
     ) -> None:
         super().__init__(**kwargs)
+        if overlap_margins is None:
+            overlap_margins = [4, 4]
+        if pooling_size is None:
+            pooling_size = [2, 2]
         size = size if size is not None else {"height": 378, "width": 378}
         size = get_size_dict(size, default_to_square=True)
         self.size = size

src/lerobot/policies/molmoact2/molmoact2_hf_model/inference.py

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-
 # Copyright 2026 The Allen Institute for Artificial Intelligence and The HuggingFace Inc. team. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -14,16 +12,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# ruff: noqa
 
 """Inference utilities for MolmoAct2"""
 
-from dataclasses import dataclass
-from typing import Any, Optional, Tuple
 from collections.abc import Iterable, Sequence
+from dataclasses import dataclass
+from typing import Any
 
 import torch
-from torch.nn import functional as F
+from torch.nn import functional as F  # noqa: N812
 from transformers.cache_utils import Cache
 from transformers.configuration_utils import PretrainedConfig
 
@@ -679,7 +676,7 @@ def _clone_static_inputs(inputs: _ActionFlowInputs) -> _ActionFlowInputs:
 
 
 def _copy_context_(dst: Any, src: Any) -> None:
-    for (dst_k, dst_v), (src_k, src_v) in zip(dst.kv_contexts, src.kv_contexts):
+    for (dst_k, dst_v), (src_k, src_v) in zip(dst.kv_contexts, src.kv_contexts, strict=False):
         dst_k.copy_(src_k)
         dst_v.copy_(src_v)
     if src.cross_mask is not None:
@@ -689,7 +686,7 @@ def _copy_context_(dst: Any, src: Any) -> None:
     if src.valid_action is not None:
         dst.valid_action.copy_(src.valid_action)
     if src.rope_cache is not None:
-        for dst_tensor, src_tensor in zip(dst.rope_cache, src.rope_cache):
+        for dst_tensor, src_tensor in zip(dst.rope_cache, src.rope_cache, strict=False):
             dst_tensor.copy_(src_tensor)
 
 

src/lerobot/policies/molmoact2/molmoact2_hf_model/modeling_molmoact2.py

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-
 # Copyright 2026 The Allen Institute for Artificial Intelligence and The HuggingFace Inc. team. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -14,24 +12,25 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# ruff: noqa
 
 """Modeling code for MolmoAct2"""
 
+# ruff: noqa: N806
+
 import json
 import math
 import os
 import re
+from collections.abc import Callable, Mapping, Sequence
 from copy import deepcopy
 from dataclasses import dataclass
-from typing import Any, Dict, List, Optional, Tuple, Union
-from collections.abc import Callable, Mapping, Sequence
+from typing import Any, Optional
 
 import numpy as np
 import torch
 import torch.utils.checkpoint
 from torch import nn
-from torch.nn import functional as F
+from torch.nn import functional as F  # noqa: N812
 from torch.nn.attention import SDPBackend, sdpa_kernel
 from transformers.activations import ACT2FN
 from transformers.cache_utils import Cache, DynamicCache
@@ -647,7 +646,7 @@ class ActionExpert(nn.Module):
                 f"got {len(encoder_kv_states)}."
             )
         kv_contexts = []
-        for block, (k_in, v_in) in zip(self.blocks, encoder_kv_states):
+        for block, (k_in, v_in) in zip(self.blocks, encoder_kv_states, strict=False):
             k_ctx = self._project_kv_tensor(k_in, self.context_k_proj)
             v_ctx = self._project_kv_tensor(v_in, self.context_v_proj)
             k_norm = block.cross_attn.k_norm
@@ -732,7 +731,7 @@ class ActionExpert(nn.Module):
         timesteps: Sequence[torch.Tensor],
     ) -> Sequence[ActionExpertStepModulation]:
         cache = []
-        for idx, step_t in enumerate(timesteps):
+        for _idx, step_t in enumerate(timesteps):
             conditioning = self._time_conditioning(step_t)
             block_modulations = []
             for block in self.blocks:
@@ -786,8 +785,8 @@ class ActionExpert(nn.Module):
         x = self.action_embed(actions)
         if context.valid_action is not None:
             x = x * context.valid_action
-        for idx, (block, kv_context, block_modulation) in enumerate(
-            zip(self.blocks, context.kv_contexts, block_modulations)
+        for _idx, (block, kv_context, block_modulation) in enumerate(
+            zip(self.blocks, context.kv_contexts, block_modulations, strict=False)
         ):
             x = block(
                 x,
@@ -2874,7 +2873,7 @@ class MolmoAct2Model(MolmoAct2PreTrainedModel):
                     depth_mask=depth_mask,
                     encoder_attention_mask=encoder_attention_mask,
                 )
-                for gate, source in zip(gate_head, sources)
+                for gate, source in zip(gate_head, sources, strict=False)
             ]
             return gates, depth_mask
         gate = self._depth_gate_from_source(
@@ -4458,7 +4457,7 @@ class MolmoAct2ForConditionalGeneration(MolmoAct2PreTrainedModel, GenerationMixi
         ```python
         >>> from PIL import Image
         >>> import requests
-        >>> from lerobot.policies.molmoact2.hf_model.modeling_molmoact2 import MolmoAct2ForConditionalGeneration
+        >>> from lerobot.policies.molmoact2.molmoact2_hf_model.modeling_molmoact2 import MolmoAct2ForConditionalGeneration
         >>> from lerobot.policies.molmoact2.processor_molmoact2 import _load_local_molmoact2_processor
 
         >>> model = MolmoAct2ForConditionalGeneration.from_pretrained("...")

src/lerobot/policies/molmoact2/molmoact2_hf_model/processing_molmoact2.py

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-
 # Copyright 2026 The Allen Institute for Artificial Intelligence and The HuggingFace Inc. team. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -14,45 +12,39 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# ruff: noqa
 
 """
 Processor class for MolmoAct2.
 """
 
-from typing import Optional, Union
-import dataclasses
-
 import numpy as np
-
+from transformers import AutoTokenizer
+from transformers.feature_extraction_utils import BatchFeature
 from transformers.image_utils import ImageInput
-from transformers.video_utils import VideoInput
 from transformers.processing_utils import (
-    Unpack,
     ProcessingKwargs,
     ProcessorMixin,
+    Unpack,
 )
-from transformers.feature_extraction_utils import BatchFeature
-from transformers.tokenization_utils_base import TextInput, PreTokenizedInput
+from transformers.tokenization_utils_base import PreTokenizedInput, TextInput
 from transformers.utils import logging
+from transformers.video_utils import VideoInput
 
-from transformers import AutoTokenizer
-from .image_processing_molmoact2 import MolmoAct2ImagesKwargs, MolmoAct2ImageProcessor
-from .video_processing_molmoact2 import MolmoAct2VideoProcessorKwargs, MolmoAct2VideoProcessor
-
+from .image_processing_molmoact2 import MolmoAct2ImageProcessor, MolmoAct2ImagesKwargs
+from .video_processing_molmoact2 import MolmoAct2VideoProcessor, MolmoAct2VideoProcessorKwargs
 
 logger = logging.get_logger(__name__)
 
 
 # Special tokens, these should be present in any tokenizer we use since the preprocessor uses them
-IMAGE_PATCH_TOKEN = f"<im_patch>"  # Where to insert high-res tokens
-IMAGE_LOW_RES_TOKEN = f"<im_low>"  # Where to insert low-res tokens
-IM_START_TOKEN = f"<im_start>"
-LOW_RES_IMAGE_START_TOKEN = f"<low_res_im_start>"
-FRAME_START_TOKEN = f"<frame_start>"
-IM_END_TOKEN = f"<im_end>"
-FRAME_END_TOKEN = f"<frame_end>"
-IM_COL_TOKEN = f"<im_col>"
+IMAGE_PATCH_TOKEN = "<im_patch>"  # nosec B105  # Where to insert high-res tokens
+IMAGE_LOW_RES_TOKEN = "<im_low>"  # nosec B105  # Where to insert low-res tokens
+IM_START_TOKEN = "<im_start>"  # nosec B105
+LOW_RES_IMAGE_START_TOKEN = "<low_res_im_start>"  # nosec B105
+FRAME_START_TOKEN = "<frame_start>"  # nosec B105
+IM_END_TOKEN = "<im_end>"  # nosec B105
+FRAME_END_TOKEN = "<frame_end>"  # nosec B105
+IM_COL_TOKEN = "<im_col>"  # nosec B105
 IMAGE_PROMPT = "<|image|>"
 VIDEO_PROMPT = "<|video|>"
 
@@ -224,7 +216,7 @@ class MolmoAct2Processor(ProcessorMixin):
             input_ids = input_ids[None, :]
             attention_mask = attention_mask[None, :]
 
-        B, S = input_ids.shape
+        B, S = input_ids.shape  # noqa: N806
 
         # Handle zero-length sequence
         if S == 0:
@@ -364,7 +356,7 @@ class MolmoAct2Processor(ProcessorMixin):
                 assert num_videos in {0, 1}, "At most one video is supported for now"
                 video_grids_i = video_grids[index : index + num_videos]
                 metadata_i = video_metadata[index : index + num_videos]
-                for video_grid, metadata in zip(video_grids_i, metadata_i):
+                for video_grid, metadata in zip(video_grids_i, metadata_i, strict=False):
                     video_string = self.get_video_string(
                         video_grid,
                         metadata.timestamps,

src/lerobot/policies/molmoact2/molmoact2_hf_model/video_processing_molmoact2.py

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-
 # Copyright 2026 The Allen Institute for Artificial Intelligence and The HuggingFace Inc. team. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -14,25 +12,23 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# ruff: noqa
 
 """Video processor class for MolmoAct2"""
 
-from functools import partial
 import os
 import warnings
+from collections.abc import Callable
 from contextlib import redirect_stdout
+from functools import partial
 from io import BytesIO
 from urllib.parse import urlparse
-from typing import Optional, Union
-from collections.abc import Callable
 
+import einops
 import numpy as np
 import requests
-import einops
 import torch
 import torchvision.transforms
-
+from transformers.feature_extraction_utils import BatchFeature
 from transformers.image_utils import (
     IMAGENET_STANDARD_MEAN,
     IMAGENET_STANDARD_STD,
@@ -41,27 +37,24 @@ from transformers.image_utils import (
     SizeDict,
     validate_kwargs,
 )
-from transformers.video_utils import (
-    VideoInput,
-    is_valid_video,
-    make_batched_videos,
-    make_batched_metadata,
-    VideoMetadata,
-)
 from transformers.processing_utils import Unpack, VideosKwargs
-from transformers.video_processing_utils import BaseVideoProcessor
-from transformers.utils import logging
-from transformers.feature_extraction_utils import BatchFeature
 from transformers.utils import (
+    TensorType,
     is_av_available,
     is_decord_available,
     is_torchcodec_available,
     is_yt_dlp_available,
-    TensorType,
     logging,
     to_numpy,
 )
-
+from transformers.video_processing_utils import BaseVideoProcessor
+from transformers.video_utils import (
+    VideoInput,
+    VideoMetadata,
+    is_valid_video,
+    make_batched_metadata,
+    make_batched_videos,
+)
 
 logger = logging.get_logger(__name__)
 
@@ -102,8 +95,8 @@ def resize_image(
         )(image)
         resized = torch.clip(resized, 0.0, 1.0).to(dtype)
     else:
-        assert image.dtype == torch.uint8, "SigLIP expects float images or uint8 images, but got {}".format(
-            image.dtype
+        assert image.dtype == torch.uint8, (
+            f"SigLIP expects float images or uint8 images, but got {image.dtype}"
         )
         in_min = 0.0
         in_max = 255.0
@@ -548,9 +541,8 @@ def get_target_fps(
         step_size = max(int(video_fps / target_fps), 1)
         num_frames_sampled_at_fps = int(total_frames / step_size)
         if num_frames_sampled == 0:
-            if "uniform" in frame_sample_mode:
-                if num_frames_sampled_at_fps > max_frames:
-                    break
+            if "uniform" in frame_sample_mode and num_frames_sampled_at_fps > max_frames:
+                break
             selected_target_fps = target_fps
             num_frames_sampled = num_frames_sampled_at_fps
 
@@ -779,13 +771,15 @@ class MolmoAct2VideoProcessor(BaseVideoProcessor):
         elif is_torchcodec_available():
             warnings.warn(
                 "`decord` is not installed and cannot be used to decode the video by default. "
-                "Falling back to `torchcodec`."
+                "Falling back to `torchcodec`.",
+                stacklevel=2,
             )
             backend = "torchcodec"
         else:
             warnings.warn(
                 "`decord` is not installed and cannot be used to decode the video by default. "
-                "Falling back to `PyAV`."
+                "Falling back to `PyAV`.",
+                stacklevel=2,
             )
             backend = "pyav"
 
@@ -795,7 +789,8 @@ class MolmoAct2VideoProcessor(BaseVideoProcessor):
                     *[
                         self.fetch_videos(x, sample_timestamps_fn=sample_timestamps_fn)
                         for x in video_url_or_urls
-                    ]
+                    ],
+                    strict=False,
                 )
             )
         else:
@@ -821,7 +816,7 @@ class MolmoAct2VideoProcessor(BaseVideoProcessor):
             assert video_metadata[0].fps is not None, "FPS must be provided for video input"
             sampled_videos = []
             sampled_metadata = []
-            for video, metadata in zip(videos, video_metadata):
+            for video, metadata in zip(videos, video_metadata, strict=False):
                 indices = sample_indices_fn(metadata=metadata)
                 metadata.frames_indices = indices
                 sampled_videos.append(video[indices])
@@ -985,11 +980,11 @@ class MolmoAct2VideoProcessor(BaseVideoProcessor):
         pixel_values_videos = np.concatenate(batch_crops, 0)
         video_token_pooling = np.concatenate(batch_pooled_patches_idx, 0)
 
-        data = dict(
-            pixel_values_videos=pixel_values_videos,
-            video_token_pooling=video_token_pooling,
-            video_grids=video_grids,
-        )
+        data = {
+            "pixel_values_videos": pixel_values_videos,
+            "video_token_pooling": video_token_pooling,
+            "video_grids": video_grids,
+        }
 
         return BatchFeature(data, tensor_type=return_tensors)
 

src/lerobot/policies/molmoact2/processor_molmoact2.py

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-
 # Copyright 2026 The Allen Institute for Artificial Intelligence and The HuggingFace Inc. team. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -14,10 +12,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+"""MolmoAct2 pre/post processing pipeline.
+
+Builds the multimodal prompt (images, discretised state, task text),
+tokenises it via the vendored MolmoAct2 processor, and handles quantile
+normalisation with optional per-dimension gripper masking.
+"""
+
 from __future__ import annotations
 
 import json
-import os
+import logging
+import math
 import re
 from contextlib import suppress
 from copy import deepcopy
@@ -27,7 +33,6 @@ from typing import TYPE_CHECKING, Any
 
 import numpy as np
 import torch
-from huggingface_hub import snapshot_download
 from torch import Tensor
 
 from lerobot.configs import FeatureType, PipelineFeatureType, PolicyFeature
@@ -54,14 +59,71 @@ from lerobot.utils.constants import (
 )
 from lerobot.utils.import_utils import _scipy_available, _transformers_available, require_package
 
-from .configuration_molmoact2 import MolmoAct2Config, infer_molmoact2_max_sequence_length
+from .configuration_molmoact2 import MolmoAct2Config
+from .modeling_molmoact2 import _hf_token, _resolve_checkpoint_location
+
+logger = logging.getLogger(__name__)
+
+MOLMOACT2_DEFAULT_NUM_IMAGES = 2
+MOLMOACT2_IMAGE_TOKENS_PER_IMAGE = 196
+MOLMOACT2_FIXED_PROMPT_TOKEN_BUDGET = 80
+MOLMOACT2_TASK_TOKEN_BUDGET = 32
+MOLMOACT2_SEQUENCE_LENGTH_MARGIN = 32
+MOLMOACT2_SEQUENCE_LENGTH_MULTIPLE = 64
+MOLMOACT2_DISCRETE_ACTION_WRAPPER_TOKENS = 4
+MOLMOACT2_MIN_DISCRETE_ACTION_TOKENS_PER_STEP = 6
+MOLMOACT2_DISCRETE_ACTION_TOKENS_PER_DIM = 0.95
+
+
+def _round_up(value: int, multiple: int) -> int:
+    return int(math.ceil(value / multiple) * multiple)
+
+
+def infer_molmoact2_max_sequence_length(
+    *,
+    num_images: int,
+    state_dim: int,
+    action_dim: int,
+    action_horizon: int,
+    include_discrete_action: bool,
+) -> int:
+    """Infer the padded text/image sequence cap from MolmoAct2's fixed token layout."""
+    if num_images < 1:
+        num_images = MOLMOACT2_DEFAULT_NUM_IMAGES
+    if state_dim < 0:
+        state_dim = 0
+    if action_dim < 1:
+        action_dim = 1
+    if action_horizon < 1:
+        action_horizon = 1
+
+    image_tokens = num_images * MOLMOACT2_IMAGE_TOKENS_PER_IMAGE
+    prompt_tokens = (
+        MOLMOACT2_FIXED_PROMPT_TOKEN_BUDGET
+        + MOLMOACT2_TASK_TOKEN_BUDGET
+        + state_dim
+        + MOLMOACT2_SEQUENCE_LENGTH_MARGIN
+    )
+    action_tokens = 0
+    if include_discrete_action:
+        action_tokens_per_step = max(
+            MOLMOACT2_MIN_DISCRETE_ACTION_TOKENS_PER_STEP,
+            math.ceil(action_dim * MOLMOACT2_DISCRETE_ACTION_TOKENS_PER_DIM),
+        )
+        action_tokens = MOLMOACT2_DISCRETE_ACTION_WRAPPER_TOKENS + action_horizon * action_tokens_per_step
+
+    return _round_up(
+        image_tokens + prompt_tokens + action_tokens,
+        MOLMOACT2_SEQUENCE_LENGTH_MULTIPLE,
+    )
+
 
 if TYPE_CHECKING or _transformers_available:
     from transformers import Qwen2Tokenizer
 
-    from .hf_model.image_processing_molmoact2 import MolmoAct2ImageProcessor
-    from .hf_model.processing_molmoact2 import MolmoAct2Processor
-    from .hf_model.video_processing_molmoact2 import MolmoAct2VideoProcessor
+    from .molmoact2_hf_model.image_processing_molmoact2 import MolmoAct2ImageProcessor
+    from .molmoact2_hf_model.processing_molmoact2 import MolmoAct2Processor
+    from .molmoact2_hf_model.video_processing_molmoact2 import MolmoAct2VideoProcessor
 else:
     Qwen2Tokenizer = None
     MolmoAct2ImageProcessor = None
@@ -69,7 +131,7 @@ else:
     MolmoAct2VideoProcessor = None
 
 if TYPE_CHECKING or (_transformers_available and _scipy_available):
-    from .hf_model.action_tokenizer import UniversalActionProcessor
+    from .molmoact2_hf_model.action_tokenizer import UniversalActionProcessor
 else:
     UniversalActionProcessor = None
 
@@ -97,32 +159,6 @@ _QUESTION_PREFIX_PATTERNS = tuple(
 )
 
 
-def _hf_token() -> str | None:
-    return os.environ.get("HF_TOKEN") or os.environ.get("HF_ACCESS_TOKEN")
-
-
-def _resolve_checkpoint_location(
-    checkpoint_path: str,
-    *,
-    revision: str | None = None,
-    force_download: bool = False,
-) -> str:
-    checkpoint_path = str(checkpoint_path or "").strip()
-    if not checkpoint_path:
-        raise ValueError("MolmoAct2 policy requires `checkpoint_path`.")
-    local_path = Path(checkpoint_path).expanduser()
-    if local_path.exists():
-        return str(local_path)
-    return snapshot_download(
-        repo_id=checkpoint_path,
-        repo_type="model",
-        revision=revision,
-        force_download=force_download,
-        ignore_patterns=["*.py", "*.pyc", "__pycache__/*"],
-        token=_hf_token(),
-    )
-
-
 def _load_hf_norm_stats_for_tag(
     checkpoint_path: str,
     *,
@@ -969,6 +1005,93 @@ class MolmoAct2PackInputsProcessorStep(ProcessorStep):
         return features
 
 
+@ProcessorStepRegistry.register(name="molmoact2_state_frame_transform")
+@dataclass
+class MolmoAct2StateFrameTransformStep(ProcessorStep):
+    """Convert robot state from arm frame to model frame before normalization.
+
+    Required for zero-shot deployment of MolmoAct2-SO100_101 on SO-100/101
+    arms calibrated with LeRobot >= 0.5.0 (v3.0 convention). The checkpoint
+    was trained on data using a different joint convention (sign flip on
+    shoulder_lift, 90 deg offset on shoulder_lift and elbow_flex).
+
+    No-op when joint_signs and joint_offsets are None (default), so this
+    step has no effect on fine-tuned models or other embodiments.
+
+    state_model = signs * arm_state + offsets
+
+    See: https://huggingface.co/docs/lerobot/backwardcomp
+    """
+
+    joint_signs: list[float] | None = None
+    joint_offsets: list[float] | None = None
+
+    def __call__(self, transition: EnvTransition) -> EnvTransition:
+        if self.joint_signs is None or self.joint_offsets is None:
+            return transition
+        observation = transition.get(TransitionKey.OBSERVATION)
+        if not isinstance(observation, dict) or OBS_STATE not in observation:
+            return transition
+        transition = transition.copy()
+        observation = observation.copy()
+        state = torch.as_tensor(observation[OBS_STATE], dtype=torch.float32).clone()
+        n = len(self.joint_signs)
+        signs = torch.tensor(self.joint_signs, dtype=torch.float32, device=state.device)
+        offsets = torch.tensor(self.joint_offsets, dtype=torch.float32, device=state.device)
+        state[..., :n] = signs * state[..., :n] + offsets
+        observation[OBS_STATE] = state
+        transition[TransitionKey.OBSERVATION] = observation
+        return transition
+
+    def transform_features(
+        self, features: dict[PipelineFeatureType, dict[str, PolicyFeature]]
+    ) -> dict[PipelineFeatureType, dict[str, PolicyFeature]]:
+        return features
+
+    def get_config(self) -> dict[str, Any]:
+        return {"joint_signs": self.joint_signs, "joint_offsets": self.joint_offsets}
+
+
+@ProcessorStepRegistry.register(name="molmoact2_action_frame_transform")
+@dataclass
+class MolmoAct2ActionFrameTransformStep(ProcessorStep):
+    """Convert model action from model frame back to arm frame after unnormalization.
+
+    Inverse of MolmoAct2StateFrameTransformStep. Required for zero-shot
+    MolmoAct2-SO100_101 on SO-100/101 arms. No-op when both fields are None.
+
+    action_arm = signs * (model_action - offsets)
+
+    See: https://huggingface.co/docs/lerobot/backwardcomp
+    """
+
+    joint_signs: list[float] | None = None
+    joint_offsets: list[float] | None = None
+
+    def __call__(self, transition: EnvTransition) -> EnvTransition:
+        if self.joint_signs is None or self.joint_offsets is None:
+            return transition
+        action = transition.get(TransitionKey.ACTION)
+        if action is None:
+            return transition
+        transition = transition.copy()
+        action = torch.as_tensor(action, dtype=torch.float32).clone()
+        n = len(self.joint_signs)
+        signs = torch.tensor(self.joint_signs, dtype=torch.float32, device=action.device)
+        offsets = torch.tensor(self.joint_offsets, dtype=torch.float32, device=action.device)
+        action[..., :n] = signs * (action[..., :n] - offsets)
+        transition[TransitionKey.ACTION] = action
+        return transition
+
+    def transform_features(
+        self, features: dict[PipelineFeatureType, dict[str, PolicyFeature]]
+    ) -> dict[PipelineFeatureType, dict[str, PolicyFeature]]:
+        return features
+
+    def get_config(self) -> dict[str, Any]:
+        return {"joint_signs": self.joint_signs, "joint_offsets": self.joint_offsets}
+
+
 @ProcessorStepRegistry.register(name="molmoact2_clamp_action")
 @dataclass
 class MolmoAct2ClampActionProcessorStep(ProcessorStep):
@@ -1031,6 +1154,10 @@ def make_molmoact2_pre_post_processors(
     input_steps: list[ProcessorStep] = [
         RenameObservationsProcessorStep(rename_map={}),
         AddBatchDimensionProcessorStep(),
+        MolmoAct2StateFrameTransformStep(
+            joint_signs=config.joint_signs,
+            joint_offsets=config.joint_offsets,
+        ),
         MolmoAct2MaskedNormalizerProcessorStep(
             features={**config.input_features, **config.output_features},
             norm_map=config.normalization_mapping,
@@ -1066,6 +1193,10 @@ def make_molmoact2_pre_post_processors(
             norm_map=config.normalization_mapping,
             stats=masked_dataset_stats,
         ),
+        MolmoAct2ActionFrameTransformStep(
+            joint_signs=config.joint_signs,
+            joint_offsets=config.joint_offsets,
+        ),
         DeviceProcessorStep(device="cpu"),
     ]