fix old docs and comments

DOCS_AUDIT.md

@@ -0,0 +1,113 @@
+# LeRobot Docs Audit
+
+**Status:** Fresh baseline for a new docs redesign effort · **Date:** 2026-07-27
+**Supersedes:** the June 2026 `DOCS_REDESIGN.md` proposal (lived on the unmerged, now-stale `docs/complete-docs-redesign` branch — abandoned; that branch is ~67k lines behind `main` and should not be resurrected). This document re-audits `docs/source/` from scratch against current `main`, since the docs tree grew substantially in the ~6 weeks between the two audits (many new policies, robots, and benchmarks landed).
+
+---
+
+## Snapshot (current state, in numbers)
+
+- **IA**: 15 top-level `_toctree.yml` sections, 81 `local:` entries, 0 broken toctree links.
+- **Files**: 97 total files in `docs/source/` = 80 real `.mdx` pages + 16 orphaned `policy_*_README.md` stubs (up from 14 in June) + 1 `contributing.md` (a genuine symlink to root `CONTRIBUTING.md`).
+- **Growth**: `.mdx` pages grew 49 → 80 in 6 months (+63%, ~5.2 pages/month), arriving in **bursts against a shared, hand-edited `_toctree.yml`** — e.g. 6 benchmark pages landed via 6 separate PRs within 48 hours (Apr 2026); 3 policy pages within 3 days (Jul 2026).
+- **CLI docs coverage improved sharply since June**: 17 of 18 `lerobot-*` commands now documented (only `lerobot-info`, a diagnostics helper, is not) — the June baseline was 6/17 undocumented.
+- **Decision content**: zero comparison/decision pages exist in `docs/source/` for Policies (15 options), Robots (11), Benchmarks (10), or Teleoperators — this equivalent content already exists, fully written, in root `AGENT_GUIDE.md` §6, but was never ported or linked in.
+- **Teleoperators**: dedicated toctree section has only 2 pages vs. 16-17 registered teleoperator types in `src/`, but all types do get at least one doc mention somewhere (usually buried inside a robot's hardware page) — a discoverability gap, not an absence of content.
+- **Orphan policy READMEs**: of the 16, 3 (Diffusion, TD-MPC, VQ-BeT) have **zero real published documentation anywhere** — the orphan stub is their only artifact. 13 duplicate an actively-maintained `.mdx` page under a different name. One (MolmoAct2) is proven to have silently rotted: a 39-line pre-refactor stub sits next to a 495-line maintained page that diverged 481 lines ago.
+- **Root `README.md` itself has drifted**: its "Supported Hardware" line omits SO-101 (the flagship robot) entirely; its "SoTA Models" table links several policies to thin orphan stubs instead of the richer tutorial pages that exist for them.
+- **4 concrete broken/stale copy-paste commands** verified in published pages (`act.mdx`, `il_robots.mdx` ×2 spots, `lerobot-dataset-v3.mdx`, `openarm.mdx` — the last added as recently as Jan 2026, so a fresh miss, not just aging drift).
+- **Process/CI**: no CODEOWNERS, no `_redirects.yml`, no doc-consistency or toctree-completeness check anywhere; the docs CI workflow triggers only on `paths: docs/**`, so code-only PRs get zero automated docs signal (empirically responsible for the one real lag found — OMX's docs page, 41 days after its code). Despite this, 18 of 19 spot-checked new integrations (EVO1, FastWAM, LingBot-VA, MolmoAct2, RTC, VLA-JEPA, X-VLA, WallOSS, Damiao, Hope Jr, OpenArm, reBot B601, Reachy 2, Unitree G1, RoboCasa365, VLABench, IsaacLab Arena, etc.) shipped docs in the *same commit* as the feature — organic discipline is currently strong.
+- **No content template** exists for policy or robot doc pages: heading sets/length vary 80-528 lines with almost no shared vocabulary; by contrast, benchmarks *do* have a written template (`adding_benchmarks.mdx`) and the resulting 8 pages are visibly consistent — direct proof a template is what produces consistency here.
+
+---
+
+## Strengths
+
+1. **Organic contributor discipline is currently much better than the June audit's numbers implied.** 18/19 spot-checked new policies/robots/benchmarks shipped docs in the same PR as the code; 17/18 CLI commands are documented; all teleoperator types get at least one mention. The underlying practice is healthier than the structural numbers (orphans, thin nav sections) suggest — the real problem is increasingly discoverability and consistency, not absence of effort.
+2. **The doc-builder CI pipeline (PR previews, main build, versioned release builds) is solid, standard infrastructure already in place** — nothing bespoke to build or maintain, and it's the same tooling Transformers uses.
+3. **A working, provably-effective template pattern already exists for one catalog (benchmarks)** — `adding_benchmarks.mdx`'s checklist + "at a glance" table produces 8 structurally consistent pages. This is the single best evidence in the repo for what fixes the policy/robot template gap, and it needs no new invention, just extension.
+4. **Genuine single-source-of-truth patterns already exist and work**: `docs/source/contributing.md` is a real symlink to root `CONTRIBUTING.md` (verified via `ls -la`/`find -type l`). Most policy `src/README.md` files are also symlinked into `docs/source/policy_*_README.md`, eliminating drift at that layer (though the docs-side stub itself remains an unlinked orphan — see weaknesses).
+5. **Zero broken toctree links**, and specific pages are genuinely high quality: `cheat-sheet.mdx` (spot-checked line-by-line against source, fully accurate), `bring_your_own_policies.mdx` (clear scope, working PR checklist), `installation.mdx`'s tables/OS tabs, and the SO-100/SO-101 hardware pages.
+6. **Root `README.md` already contains a usable taxonomy for policies** (Imitation Learning / RL / VLAs / World Models / Reward Models) that the flat 15-item Policies sidebar never adopted — the raw material for a better IA already exists in-repo.
+
+---
+
+## Weaknesses
+
+### High
+- **No comparison/decision-guidance page for any multi-option category** (Policies=15, Robots=11, Benchmarks=10, Teleoperators) — the exact content (decision rules, profiling snapshot) already exists in `AGENT_GUIDE.md` §6 but was never ported into `docs/source`.
+- **The landing page (`index.mdx`) provides zero navigation** — 23 lines of marketing copy and a Discord link, no path to installation, cheat-sheet, or audience-specific guidance.
+- **Teleoperators' dedicated nav section (2 pages) badly undersells real coverage** (16-17 implementations, all mentioned somewhere) — a new user browsing that sidebar section would wrongly conclude only phone/Isaac teleop exist. Content exists; it's a pure discoverability failure.
+- **Multiple concrete broken/stale CLI examples in published, frequently copy-pasted pages**: `act.mdx` tells readers to eval with `lerobot-record` while the shown code uses `lerobot-rollout`; an identical shell-breaking snippet (`\`-terminated comment swallowing a continuation) is duplicated in `il_robots.mdx` and `lerobot-dataset-v3.mdx`; `il_robots.mdx:421` uses the dead `--control.push_to_hub` flag namespace; `openarm.mdx:208-210` (added Jan 2026) gives a `lerobot-record` example with flat pre-draccus flags that don't exist on the current config classes.
+- **3 shipping policies (Diffusion, TD-MPC, VQ-BeT) have zero real published documentation** — only a thin, toctree-unreferenced stub exists for each.
+- **Root `README.md` has drifted as the project scaled**: its Supported Hardware line omits SO-101 entirely; its SoTA Models table links ACT/Diffusion/VQ-BeT/Multitask-DiT/TDMPC/GR00T/SmolVLA to thin orphan stubs instead of the richer tutorial pages that exist for several of them.
+- **No content template for policy/robot doc pages, unlike benchmarks** — heading sets and length vary 80-528 lines with almost no shared vocabulary (`molmoact2.mdx` has no Overview section at all; `smolvla.mdx` has no Overview/Architecture/Citation/License and reads as pure tutorial).
+- **Docs CI triggers only on `paths: docs/**`** — code-only PRs get zero automated docs signal; this is the mechanism directly responsible for the one measured lag (OMX's docs page shipped 41 days after its code, in a separate PR).
+- **Proof that orphan-stub drift isn't hypothetical**: `policy_molmoact2_README.md` is a stale 39-line pre-refactor snapshot sitting 481 lines behind the maintained 495-line page it once mirrored — nothing caught this silently rotting.
+
+### Medium
+- 16 orphaned `policy_*_README.md` files unreferenced by the toctree; 13 are pure duplicate cruft shadowing a maintained same-topic `.mdx` page, creating a false "two files to keep in sync" impression for contributors.
+- No `_redirects.yml` anywhere — future cleanup of the orphans/renames has no 404 safety net.
+- `installation.mdx` ends on a dangling forward-reference ("follow the link below to use LeRobot with your robot") — no link follows.
+- `cheat-sheet.mdx`'s "Policy Types" line is stale (`act, diffusion, smolvla, pi05`) against the current 15-entry Policies section, and lists `diffusion`, which has no working toctree page at all.
+- "Tutorials" (10 pages) mixes beginner, contributor, and RL-researcher content in one flat, unlabeled list.
+- The EnvHub feature family is split inconsistently across two unrelated sections (`envhub.mdx`/`envhub_leisaac.mdx` under Simulation, `envhub_isaaclab_arena.mdx` under Benchmarks) despite identical framing/opening text.
+- Admonition syntax is split GFM `[!NOTE]` vs. doc-builder `<Tip>` across sampled pages; since the site actually builds with `hf-doc-builder`, the majority pattern may not render as a styled callout at all (plausible, not independently render-verified).
+- No CODEOWNERS file anywhere — zero designated reviewer routing for `docs/source`.
+- `CONTRIBUTING.md` never links the good in-repo extension guides (`adding_benchmarks.mdx`, `bring_your_own_policies.mdx`, `integrate_hardware.mdx`) and states no docs-required policy.
+- The "docs required" PR checklist convention is applied inconsistently: Policies and Benchmarks have an explicit required-docs checklist; `integrate_hardware.mdx` (Robots/Teleoperators) has none — a plausible root cause of the Teleoperators gap above.
+- Growth repeatedly stacks simultaneous PRs against one shared, hand-edited `_toctree.yml` (6 benchmark PRs in 48h; 3 policy PRs in 3 days) — a merge/oversight risk even though no damage from it was found yet.
+- `policy_sarm_README.md` has no source of truth left to sync against at all (SARM moved `policies/`→`rewards/`, no README carried over) — pure abandoned cruft next to the real 593-line `sarm.mdx`.
+- No automated check anywhere for toctree completeness or README/mdx sync — the only CI gate is whether the doc-builder build succeeds, which doesn't catch missing coverage.
+
+### Low
+- No dedicated "Motors" section despite `motors/` being named as a distinct hardware layer in `CLAUDE.md`; `feetech.mdx`/`damiao.mdx` sit in a catch-all "Resources" section instead.
+- "Sensors" is a single-page top-level nav section (`cameras.mdx` only).
+- Policies (15), Benchmarks (10), and Robots (11) are flat, ungrouped lists with no internal sub-headings, despite `README.md` already having a usable taxonomy that could be reused.
+- "SO-101" vs. "SO101" naming is inconsistent across ~15 files, and even within a single file (`so100.mdx` uses both).
+- `hilserl.mdx` (950 lines) and `il_robots.mdx` (638 lines) each mix tutorial, reference, and troubleshooting content in one long page.
+- `reachy2_camera` has zero doc mentions anywhere; the `zmq` camera backend is documented only incidentally inside `unitree_g1.mdx` rather than centrally in `cameras.mdx`.
+- The PR template's "Documentation updated" line is a self-reported, unenforced checkbox.
+
+---
+
+## Recommendations
+
+### 1. Quick wins (small effort, ship this week, no maintainer proposal needed)
+- Fix the 4 verified broken commands: `act.mdx` (`lerobot-record`→`lerobot-rollout`), the duplicated shell-breaking snippet in `il_robots.mdx` + `lerobot-dataset-v3.mdx`, `il_robots.mdx`'s `--control.push_to_hub`→`--dataset.push_to_hub`, and `openarm.mdx`'s invalid flat-flag record example.
+- Delete the 3 fully-orphaned policy stubs (Diffusion, TD-MPC, VQ-BeT) and give each a real toctree page by promoting the existing `src/` README content.
+- Delete the remaining 13 duplicate orphan stubs and the dead `policy_sarm_README.md`.
+- Fix `installation.mdx`'s dangling ending and `cheat-sheet.mdx`'s stale policy-type list.
+- Fix root `README.md`: add SO-101 to the Supported Hardware line; repoint the SoTA Models table's links from orphan stubs to the richer existing tutorial pages.
+- Move `envhub_isaaclab_arena.mdx` into Simulation (one-line YAML change).
+- Add 2-4 orientation sentences + links to the top of `index.mdx` (installation, cheat-sheet, "I have hardware" / "I don't" / "I want to contribute") without touching its marketing framing.
+- Publish a single "Choosing a policy" page that ports the already-written decision rules from `AGENT_GUIDE.md` §6 — highest-leverage fix available.
+- Start a `docs/source/_redirects.yml` now, before the orphan cleanup above creates the first real dead links.
+- No action needed on the `contributing.md` "duplication" claim — verified it's a working symlink, not an anti-pattern.
+
+### 2. Structural / UX changes (need a proposal + maintainer buy-in, phase as separate PRs)
+- Split "Tutorials" into an explicit beginner-facing section vs. an "Advanced & Research/Contributor" section (mechanical YAML reorg, no content rewrites).
+- Add a "Teleoperators" index page listing all types with one-line descriptions and links to wherever each is actually documented today.
+- Re-group the flat Policies/Benchmarks/Robots lists into sub-headings reusing the taxonomy `README.md` already has.
+- Treat a dedicated "Motors" section, deeper sub-grouping, and closing the remaining teleoperator/robot coverage gaps as a phased backlog of independently reviewable PRs rather than one restructure.
+- Standardize SO-101/SO101 naming and (after confirming actual doc-builder rendering behavior) the admonition syntax, each as one mechanical, low-risk PR.
+- Longer-term and biggest-ticket: port more of `AGENT_GUIDE.md`'s procedural content (training duration heuristics, eval targets, data-collection tips) into the published site.
+
+### 3. Maintainability / process changes (prevent debt from reaccumulating at the current growth rate)
+- Port `adding_benchmarks.mdx`'s explicit "writing a doc page" checklist/template into `bring_your_own_policies.mdx` and `integrate_hardware.mdx`.
+- Add a CODEOWNERS entry for `docs/source/` (and ideally `_toctree.yml` specifically) so docs PRs get routed to a real reviewer.
+- Link the extension guides from `CONTRIBUTING.md` and state a docs-required policy there.
+- Add a lightweight CI/pre-commit script (not a full doc-builder run) that fails when (a) a `docs/source/*.mdx` file isn't reachable from `_toctree.yml`, or (b) a new `register_subclass` policy/robot/teleoperator/env lands with no corresponding doc file in the same diff.
+- Decide the fate of the `policy_*_README.md` symlink convention going forward: it is currently self-perpetuating because `bring_your_own_policies.mdx`'s own checklist instructs new contributors to create the file that ends up orphaned. Either fold citation/paper content into the main `.mdx` tutorial, or wire the stub into the toctree as a linked citation anchor.
+- Make the PR template's "Documentation updated" checkbox actionable (e.g., "(N/A if this PR only touches tests/CI/refactors)").
+- Defer heavier generated-registry/support-matrix tooling (Transformers/Ultralytics-style single source of truth) until closer to 1.0.
+
+---
+
+## Notes on cross-checking
+
+Five independent audit passes fed this report; two disagreements were resolved during synthesis:
+- **Toctree section count** — 15 is correct (independently parsed twice from `_toctree.yml`).
+- **`contributing.md`** — it's a working symlink, not a hand-duplicated anti-pattern; one pass's `diff`-based claim didn't survive checking `find -type l`.
+- **Orphan-README "sync mechanism"** — mostly fixed at the `src/`↔`docs` layer via symlinks, but that just moved the unresolved drift to the docs-side stub's absence from the toctree, and left old pre-symlink stubs (MolmoAct2) as dead leftovers.
+- **Teleoperators coverage** — the nav-section framing ("~2/16") and the "mentioned somewhere" framing are both true; the real gap is discoverability, not content.

docs/source/act.mdx

@@ -76,7 +76,7 @@ If your local computer doesn't have a powerful GPU, you can utilize Google Colab
 
 ## Evaluating ACT
 
-Once training is complete, you can evaluate your ACT policy using the `lerobot-record` command with your trained policy. This will run inference and record evaluation episodes:
+Once training is complete, you can evaluate your ACT policy using the `lerobot-rollout` command with your trained policy. This will run inference and record evaluation episodes:
 
 ```bash
 lerobot-rollout \

docs/source/earthrover_mini_plus.mdx

@@ -194,8 +194,8 @@ lerobot-record \
     --dataset.single_task="Navigate around obstacles" \
     --dataset.streaming_encoding=true \
     --dataset.encoder_threads=2 \
-    # --dataset.rgb_encoder.vcodec=auto \
     --display_data=true
+    # Optionally, set --dataset.rgb_encoder.vcodec=auto to pick a specific video codec
 ```
 
 Replace `your_username/dataset_name` with your Hugging Face username and a name for your dataset.

docs/source/hope_jr.mdx

@@ -232,8 +232,8 @@ lerobot-record \
     --dataset.private=true \
     --dataset.streaming_encoding=true \
     --dataset.encoder_threads=2 \
-    # --dataset.rgb_encoder.vcodec=auto \
     --display_data=true
+    # Optionally, set --dataset.rgb_encoder.vcodec=auto to pick a specific video codec
 ```
 
 ### Replay
@@ -278,6 +278,6 @@ lerobot-record \
   --dataset.num_episodes=10 \
   --dataset.streaming_encoding=true \
   --dataset.encoder_threads=2 \
-  # --dataset.rgb_encoder.vcodec=auto \
   --policy.path=outputs/train/hopejr_hand/checkpoints/last/pretrained_model
+  # Optionally, set --dataset.rgb_encoder.vcodec=auto to pick a specific video codec
 ```

docs/source/il_robots.mdx

@@ -207,8 +207,8 @@ lerobot-record \
     --dataset.num_episodes=5 \
     --dataset.single_task="Grab the black cube" \
     --dataset.streaming_encoding=true \
-    # --dataset.rgb_encoder.vcodec=auto \
     --dataset.encoder_threads=2
+    # Optionally, set --dataset.rgb_encoder.vcodec=auto to pick a specific video codec
 ```
 </hfoption>
 <hfoption id="API example">
@@ -418,7 +418,7 @@ If you want to dive deeper into this important topic, you can check out the [blo
 
 ## Visualize a dataset
 
-If you uploaded your dataset to the hub with `--control.push_to_hub=true`, you can [visualize your dataset online](https://huggingface.co/spaces/lerobot/visualize_dataset) by copy pasting your repo id given by:
+If you uploaded your dataset to the hub with `--dataset.push_to_hub=true`, you can [visualize your dataset online](https://huggingface.co/spaces/lerobot/visualize_dataset) by copy pasting your repo id given by:
 
 ```bash
 echo ${HF_USER}/so101_test

docs/source/language_and_recipes.mdx

@@ -141,17 +141,6 @@ sample["target_message_indices"]
 
 The renderer does not apply a tokenizer chat template. Policy processors decide how to serialize the messages for their backbone, which keeps the same dataset usable across SmolVLA, Pi0.5, and any future VLM that expects OpenAI-style chat messages.
 
-## Blends
-
-Blend recipes select one weighted sub-recipe deterministically from the sample index.
-`recipes/subtask_mem.yaml` trains the compact core blend — high-level subtask prediction, low-level execution, and memory. `recipes/subtask_mem_vqa_speech.yaml` is the fuller variant that also adds VQA and spoken interjection responses.
-
-A message recipe with a supervised assistant turn on the `low_level` stream trains
-the π0.5 paper's joint sequence instead of a blend: the target span gets text CE
-while also conditioning the action losses in the same forward.
-`recipes/subtask_joint.yaml` is the provided example; pair it with
-`--policy.joint_subtask_conditioning=true` at inference.
-
 ## Graceful absence
 
 If both language columns are missing, `None`, or empty, `RenderMessagesStep` is a no-op.

docs/source/lerobot-dataset-v3.mdx

@@ -44,8 +44,8 @@ lerobot-record \
   --dataset.num_episodes=5 \
   --dataset.single_task="Grab the black cube" \
   --dataset.streaming_encoding=true \
-  # --dataset.rgb_encoder.vcodec=auto \
   --dataset.encoder_threads=2
+  # Optionally, set --dataset.rgb_encoder.vcodec=auto to pick a specific video codec
 ```
 
 See the [recording guide](./il_robots#record-a-dataset) for more details.

docs/source/openarm.mdx

@@ -205,9 +205,10 @@ lerobot-record \
     --teleop.type=openarm_leader \
     --teleop.port=can1 \
     --teleop.id=my_leader \
-    --repo-id=my_hf_username/my_openarm_dataset \
-    --fps=30 \
-    --num-episodes=10
+    --dataset.repo_id=my_hf_username/my_openarm_dataset \
+    --dataset.single_task="Grab the black cube" \
+    --dataset.fps=30 \
+    --dataset.num_episodes=10
 ```
 
 ## Configuration Options

docs/source/reachy2.mdx

@@ -161,8 +161,8 @@ lerobot-record \
     --dataset.private=true \
     --dataset.streaming_encoding=true \
     --dataset.encoder_threads=2 \
-    # --dataset.rgb_encoder.vcodec=auto \
     --display_data=true
+    # Optionally, set --dataset.rgb_encoder.vcodec=auto to pick a specific video codec
 ```
 
 #### Specific Options
@@ -203,8 +203,8 @@ lerobot-record \
     --dataset.private=true \
     --dataset.streaming_encoding=true \
     --dataset.encoder_threads=2 \
-    # --dataset.rgb_encoder.vcodec=auto \
     --display_data=true
+    # Optionally, set --dataset.rgb_encoder.vcodec=auto to pick a specific video codec
 ```
 
 ##### `--robot.use_external_commands`

docs/source/smolvla.mdx

@@ -100,20 +100,19 @@ Once you are logged in, you can run inference in your setup by doing:
 lerobot-rollout \
   --strategy.type=base \
   --robot.type=so101_follower \
-  --robot.port=/dev/ttyACM0 \ # <- Use your port
-  --robot.id=my_blue_follower_arm \ # <- Use your robot id
-  --robot.cameras="{ front: {type: opencv, index_or_path: 8, width: 640, height: 480, fps: 30}}" \ # <- Use your cameras
-  --task="Grasp a lego block and put it in the bin." \ # <- Use the same task description you used in your dataset recording
-  # <- RTC optional, use when running on low power hardware \
-  # --inference.type=rtc \
-  # --inference.rtc.execution_horizon=10 \
-  # --inference.rtc.max_guidance_weight=10.0 \
-  # <- Teleop optional if you want to teleoperate in between episodes \
-  # --teleop.type=so100_leader \
-  # --teleop.port=/dev/ttyACM0 \
-  # --teleop.id=my_red_leader_arm \
-  # --display_data=true #optional use if you want to see the camera stream \
-  --policy.path=HF_USER/FINETUNE_MODEL_NAME # <- Use your fine-tuned model
+  --robot.port=/dev/ttyACM0 \
+  --robot.id=my_blue_follower_arm \
+  --robot.cameras="{ front: {type: opencv, index_or_path: 8, width: 640, height: 480, fps: 30}}" \
+  --task="Grasp a lego block and put it in the bin." \
+  --policy.path=HF_USER/FINETUNE_MODEL_NAME
 ```
 
+Replace `--robot.port`, `--robot.id`, `--robot.cameras`, `--task`, and `--policy.path` with your own port, robot ID, camera setup, task description (matching what you used when recording your dataset), and fine-tuned model repo ID.
+
+A few optional flags you can add to the command above:
+
+- **RTC** (useful on low-power hardware): `--inference.type=rtc --inference.rtc.execution_horizon=10 --inference.rtc.max_guidance_weight=10.0`
+- **Teleoperate in between episodes**: `--teleop.type=so100_leader --teleop.port=/dev/ttyACM0 --teleop.id=my_red_leader_arm`
+- **See the camera stream**: `--display_data=true`
+
 Depending on your evaluation setup, you can configure the duration and the number of episodes to record for your evaluation suite.

src/lerobot/configs/default.py

@@ -33,8 +33,6 @@ class DatasetConfig:
     # looked up under $HF_LEROBOT_HOME/repo_id and Hub downloads use a revision-safe cache under $HF_LEROBOT_HOME/hub.
     root: str | None = None
     episodes: list[int] | None = None
-    # Episode indices to drop (e.g. corrupt or heterogeneous ones). Applied on top of `episodes`.
-    exclude_episodes: list[int] | None = None
     image_transforms: ImageTransformsConfig = field(default_factory=ImageTransformsConfig)
     revision: str | None = None
     use_imagenet_stats: bool = True
@@ -64,10 +62,6 @@ class DatasetConfig:
             if len(self.episodes) != len(set(self.episodes)):
                 duplicates = sorted({ep for ep in self.episodes if self.episodes.count(ep) > 1})
                 raise ValueError(f"Episode indices contain duplicates: {duplicates}")
-        if self.exclude_episodes is not None and any(ep < 0 for ep in self.exclude_episodes):
-            raise ValueError(
-                f"exclude_episodes must be non-negative, got: {[ep for ep in self.exclude_episodes if ep < 0]}"
-            )
 
 
 @dataclass

src/lerobot/configs/recipe.py

@@ -78,7 +78,7 @@ class MessageTurn:
             raise ValueError(f"Unsupported message stream: {self.stream!r}")
         if self.content is None and self.tool_calls_from is None:
             raise ValueError("MessageTurn.content is required unless tool_calls_from is set.")
-        if self.content is not None and not isinstance(self.content, str | list):
+        if self.content is not None and not isinstance(self.content, (str, list)):
             raise TypeError("MessageTurn.content must be a string, a list of HF-style blocks, or None.")
         if isinstance(self.content, list):
             for block in self.content:
@@ -147,7 +147,7 @@ class TrainingRecipe:
         return cls.from_dict(data)
 
     def _validate_message_recipe(self) -> None:
-        """Validate bindings and require text or low-level action supervision."""
+        """Ensure every templated binding is known and at least one turn is a target."""
         assert self.messages is not None
         known_bindings = set(DEFAULT_BINDINGS) | set(self.bindings or {}) | {"task"}
 
@@ -156,14 +156,8 @@ class TrainingRecipe:
             if missing:
                 raise ValueError(f"MessageTurn references unknown binding(s): {sorted(missing)}")
 
-        has_target = any(turn.target for turn in self.messages)
-        has_low_level = any(turn.stream == "low_level" for turn in self.messages)
-        if not (has_target or has_low_level):
-            raise ValueError(
-                "Message recipes must contain at least one supervised turn — "
-                "either ``target: true`` (text CE) or ``stream: low_level`` "
-                "(flow/action loss)."
-            )
+        if not any(turn.target for turn in self.messages):
+            raise ValueError("Message recipes must contain at least one target turn.")
 
     def _validate_blend_recipe(self) -> None:
         """Ensure each blend component is a non-empty, weighted message recipe."""

src/lerobot/configs/recipes/subtask.yaml

@@ -1,16 +0,0 @@
-# Predicts subtasks from tasks and trains subtask-conditioned action flow without memory or plans.
-# Requires `subtask` annotations; samples with missing `if_present` bindings do not render.
-
-blend:
-
-  high_level_subtask:
-    weight: 0.30
-    messages:
-      - {role: user, content: "${task}", stream: high_level}
-      - {role: assistant, content: "${subtask}", stream: high_level, target: true, if_present: subtask}
-
-  low_level_execution:
-    weight: 0.70
-    messages:
-      # The low-level stream trains action flow on the generated or annotated subtask.
-      - {role: user, content: "${subtask}", stream: low_level, if_present: subtask}

src/lerobot/configs/recipes/subtask_joint.yaml

@@ -1,13 +0,0 @@
-# Paper-style joint sequence (pi0.5 §IV-B): one sample supervises the subtask
-# text with CE and, because the assistant turn is part of the prefix, conditions
-# the FAST and flow action losses on the same annotated subtask in one forward.
-# The supervised span is attended causally; the action losses see task + subtask.
-#
-# Pair with `--policy.joint_subtask_conditioning=true` at inference so the flow
-# prefix reproduces this layout (task turn with state + causal generated subtask).
-# Samples without a `subtask` annotation fall back to a plain task-prompt
-# low-level sample via `if_present`.
-
-messages:
-  - {role: user, content: "${task}", stream: low_level}
-  - {role: assistant, content: "${subtask}", stream: low_level, target: true, if_present: subtask}

src/lerobot/configs/recipes/subtask_mem.yaml

@@ -1,30 +0,0 @@
-# Trains subtask prediction, subtask-conditioned action flow, and memory updates without plans.
-# Requires `subtask` and `memory`; missing `if_present` bindings skip the affected sub-recipe.
-
-blend:
-
-  high_level_subtask:
-    weight: 0.25
-    messages:
-      - {role: user, content: "${task}", stream: high_level}
-      - {role: assistant, content: "${subtask}", stream: high_level, target: true, if_present: subtask}
-
-  low_level_execution:
-    weight: 0.60
-    messages:
-      # The low-level stream trains action flow on the generated or annotated subtask.
-      - {role: user, content: "${subtask}", stream: low_level, if_present: subtask}
-
-  memory_update:
-    # `active_at` densifies sparse boundaries while preserving the prior-memory/subtask mapping.
-    # Inference controls update timing through `subtask_change` events.
-    weight: 0.15
-    bindings:
-      prior_memory: "nth_prev(style=memory, offset=1)"
-      current_memory: "active_at(t, style=memory)"
-      completed_subtask: "nth_prev(style=subtask, offset=1)"
-    messages:
-      - {role: user, content: "${task}", stream: high_level}
-      - {role: assistant, content: "Previous memory: ${prior_memory}", stream: high_level, if_present: prior_memory}
-      - {role: user, content: "Completed subtask: ${completed_subtask}", stream: high_level, if_present: completed_subtask}
-      - {role: assistant, content: "${current_memory}", stream: high_level, target: true, if_present: current_memory}

src/lerobot/configs/recipes/subtask_mem_vqa_speech.yaml

@@ -1,70 +0,0 @@
-# Adds memory, spoken interjection responses, and camera-grounded VQA to subtask/action training.
-# Missing optional annotations skip only their sub-recipe; `say` tool calls tokenize as `<say>...</say>`.
-
-blend:
-
-  high_level_subtask:
-    weight: 0.25
-    messages:
-      - {role: user, content: "${task}", stream: high_level}
-      - {role: assistant, content: "${subtask}", stream: high_level, target: true, if_present: subtask}
-
-  low_level_execution:
-    weight: 0.40
-    messages:
-      # The low-level stream trains action flow on the generated or annotated subtask.
-      - {role: user, content: "${subtask}", stream: low_level, if_present: subtask}
-
-  memory_update:
-    # `active_at` densifies sparse boundaries while preserving the prior-memory/subtask mapping.
-    # Inference controls update timing through `subtask_change` events.
-    weight: 0.10
-    bindings:
-      prior_memory: "nth_prev(style=memory, offset=1)"
-      current_memory: "active_at(t, style=memory)"
-      completed_subtask: "nth_prev(style=subtask, offset=1)"
-    messages:
-      - {role: user, content: "${task}", stream: high_level}
-      - {role: assistant, content: "Previous memory: ${prior_memory}", stream: high_level, if_present: prior_memory}
-      - {role: user, content: "Completed subtask: ${completed_subtask}", stream: high_level, if_present: completed_subtask}
-      - {role: assistant, content: "${current_memory}", stream: high_level, target: true, if_present: current_memory}
-
-  user_interjection_response:
-    weight: 0.10
-    bindings:
-      interjection: "emitted_at(t, style=interjection)"
-      speech: "emitted_at(t, role=assistant, tool_name=say)"
-    messages:
-      - {role: user, content: "${task}", stream: high_level}
-      - {role: user, content: "${interjection}", stream: high_level, if_present: interjection}
-      # The assistant target is a `say` tool call flattened to a `<say>...</say>` marker.
-      - {role: assistant, stream: high_level, target: true, if_present: speech, tool_calls_from: speech}
-
-  # Each camera uses a separate VQA sub-recipe for view-specific binding.
-  ask_vqa_top:
-    weight: 0.075
-    bindings:
-      vqa_query: "emitted_at(t, style=vqa, role=user, camera=observation.images.front)"
-      vqa: "emitted_at(t, style=vqa, role=assistant, camera=observation.images.front)"
-    messages:
-      - role: user
-        stream: high_level
-        if_present: vqa_query
-        content:
-          - {type: image, feature: observation.images.front}
-          - {type: text, text: "${vqa_query}"}
-      - {role: assistant, content: "${vqa}", stream: high_level, target: true, if_present: vqa}
-
-  ask_vqa_wrist:
-    weight: 0.075
-    bindings:
-      vqa_query: "emitted_at(t, style=vqa, role=user, camera=observation.images.wrist)"
-      vqa: "emitted_at(t, style=vqa, role=assistant, camera=observation.images.wrist)"
-    messages:
-      - role: user
-        stream: high_level
-        if_present: vqa_query
-        content:
-          - {type: image, feature: observation.images.wrist}
-          - {type: text, text: "${vqa_query}"}
-      - {role: assistant, content: "${vqa}", stream: high_level, target: true, if_present: vqa}

src/lerobot/datasets/dataset_reader.py

@@ -163,40 +163,10 @@ class DatasetReader:
     def _load_hf_dataset(self) -> datasets.Dataset:
         """hf_dataset contains all the observations, states, actions, rewards, etc."""
         features = get_hf_features_from_features(self._meta.features)
-        # Annotated datasets may have language columns absent from metadata.
-        # Extend the schema before the strict Parquet cast.
-        features = self._extend_features_with_language_columns(features)
         hf_dataset = load_nested_dataset(self.root / "data", features=features, episodes=self.episodes)
         hf_dataset.set_transform(hf_transform_to_torch)
         return hf_dataset
 
-    def _extend_features_with_language_columns(self, features: datasets.Features) -> datasets.Features:
-        """Register language columns found in Parquet but missing from metadata."""
-        # Leave empty datasets to fail through the normal loading path.
-        try:
-            sample = next((self.root / "data").glob("*/*.parquet"))
-        except StopIteration:
-            return features
-
-        from pyarrow import parquet as _pq  # noqa: PLC0415
-
-        schema_names = set(_pq.read_schema(sample).names)
-        from .language import (  # noqa: PLC0415
-            LANGUAGE_EVENTS,
-            LANGUAGE_PERSISTENT,
-            language_events_column_feature,
-            language_persistent_column_feature,
-        )
-
-        extra: dict[str, object] = {}
-        if LANGUAGE_PERSISTENT in schema_names and LANGUAGE_PERSISTENT not in features:
-            extra[LANGUAGE_PERSISTENT] = language_persistent_column_feature()
-        if LANGUAGE_EVENTS in schema_names and LANGUAGE_EVENTS not in features:
-            extra[LANGUAGE_EVENTS] = language_events_column_feature()
-        if not extra:
-            return features
-        return datasets.Features({**features, **extra})
-
     def _check_cached_episodes_sufficient(self) -> bool:
         """Check if the cached dataset contains all requested episodes and their video files."""
         if self.hf_dataset is None or len(self.hf_dataset) == 0:

src/lerobot/datasets/factory.py

@@ -66,17 +66,6 @@ def resolve_delta_timestamps(
     return delta_timestamps
 
 
-def _resolve_episodes(
-    episodes: list[int] | None, exclude_episodes: list[int] | None, total_episodes: int
-) -> list[int] | None:
-    """Apply an episode exclusion list on top of an optional allowlist."""
-    if not exclude_episodes:
-        return episodes
-    base = episodes if episodes is not None else list(range(total_episodes))
-    excluded = set(exclude_episodes)
-    return [episode for episode in base if episode not in excluded]
-
-
 def make_dataset(cfg: TrainPipelineConfig) -> LeRobotDataset | MultiLeRobotDataset:
     """Handles the logic of setting up delta timestamps and image transforms before creating a dataset.
 
@@ -98,14 +87,11 @@ def make_dataset(cfg: TrainPipelineConfig) -> LeRobotDataset | MultiLeRobotDatas
             cfg.dataset.repo_id, root=cfg.dataset.root, revision=cfg.dataset.revision
         )
         delta_timestamps = resolve_delta_timestamps(cfg.trainable_config, ds_meta)
-        episodes = _resolve_episodes(
-            cfg.dataset.episodes, cfg.dataset.exclude_episodes, ds_meta.total_episodes
-        )
         if not cfg.dataset.streaming:
             dataset = LeRobotDataset(
                 cfg.dataset.repo_id,
                 root=cfg.dataset.root,
-                episodes=episodes,
+                episodes=cfg.dataset.episodes,
                 delta_timestamps=delta_timestamps,
                 image_transforms=image_transforms,
                 revision=cfg.dataset.revision,
@@ -118,7 +104,7 @@ def make_dataset(cfg: TrainPipelineConfig) -> LeRobotDataset | MultiLeRobotDatas
             dataset = StreamingLeRobotDataset(
                 cfg.dataset.repo_id,
                 root=cfg.dataset.root,
-                episodes=episodes,
+                episodes=cfg.dataset.episodes,
                 delta_timestamps=delta_timestamps,
                 image_transforms=image_transforms,
                 revision=cfg.dataset.revision,

src/lerobot/datasets/language_render.py

@@ -162,28 +162,14 @@ def render_sample(
     task: str | None = None,
     dataset_ctx: Any | None = None,
 ) -> RenderedMessages | None:
-    """Resolve one sample's bindings and render its message recipe.
+    """Render the chat-style messages for a single dataset sample.
 
-    Returns ``None`` when no text or low-level action supervision applies.
+    Resolves the recipe's bindings against ``persistent`` and ``events`` rows
+    at frame timestamp ``t``, then expands the recipe's message templates.
+    Returns ``None`` if the resolved sample contains no target message.
     """
     persistent_rows = _normalize_rows(persistent or [])
     event_rows = _normalize_rows(events or [])
-
-    # Route sparse VQA frames to a matching view-specific component before weighted selection.
-    # This avoids dropping annotated frames or selecting VQA without annotations.
-    if recipe.blend is not None:
-        vqa_rendered = _render_vqa_if_present(
-            recipe,
-            persistent=persistent_rows,
-            events=event_rows,
-            t=t,
-            sample_idx=sample_idx,
-            task=task,
-            dataset_ctx=dataset_ctx,
-        )
-        if vqa_rendered is not None:
-            return vqa_rendered
-
     selected_recipe = _select_recipe(recipe, sample_idx)
     bindings = _resolve_bindings(
         selected_recipe,
@@ -197,55 +183,6 @@ def render_sample(
     return _render_message_recipe(selected_recipe, bindings)
 
 
-def _render_vqa_if_present(
-    recipe: TrainingRecipe,
-    *,
-    persistent: Sequence[LanguageRow],
-    events: Sequence[LanguageRow],
-    t: float,
-    sample_idx: int,
-    task: str | None,
-    dataset_ctx: Any | None,
-) -> RenderedMessages | None:
-    """Render a matching VQA component, or return ``None`` for normal selection.
-
-    Multiple matching views are selected deterministically by relative weight.
-    """
-    assert recipe.blend is not None
-    renderable: list[tuple[float, RenderedMessages]] = []
-    for name, component in recipe.blend.items():
-        if not name.startswith("ask_vqa"):
-            continue
-        bindings = _resolve_bindings(
-            component,
-            persistent=persistent,
-            events=events,
-            t=t,
-            sample_idx=sample_idx,
-            task=task,
-            dataset_ctx=dataset_ctx,
-        )
-        rendered = _render_message_recipe(component, bindings)
-        if rendered is not None:
-            renderable.append((float(component.weight or 0.0), rendered))
-
-    if not renderable:
-        return None
-    if len(renderable) == 1:
-        return renderable[0][1]
-
-    # Choose among matching cameras by relative weight, or uniformly when all weights are zero.
-    total = sum(w for w, _ in renderable) or float(len(renderable))
-    digest = hashlib.blake2b(f"vqa:{sample_idx}".encode(), digest_size=8).digest()
-    draw = int.from_bytes(digest, "big") / 2**64 * total
-    cumulative = 0.0
-    for w, rendered in renderable:
-        cumulative += w or (total / len(renderable))
-        if draw < cumulative:
-            return rendered
-    return renderable[-1][1]
-
-
 def _select_recipe(recipe: TrainingRecipe, sample_idx: int) -> TrainingRecipe:
     """Pick a deterministic blend component for ``sample_idx`` (or return ``recipe``)."""
     if recipe.blend is None:
@@ -409,9 +346,7 @@ def _render_message_recipe(
         if turn.target:
             target_indices.append(message_idx)
 
-    # Keep samples with either text targets or low-level action supervision.
-    has_low_level = any(stream == "low_level" for stream in streams)
-    if not target_indices and not has_low_level:
+    if not target_indices:
         return None
 
     rendered = {
@@ -468,12 +403,14 @@ def _validate_rendered(rendered: RenderedMessages) -> None:
 
     if len(streams) != len(messages):
         raise ValueError("message_streams must be aligned with messages.")
-    # Require text or low-level action supervision.
-    if not target_indices and not any(s == "low_level" for s in streams):
-        raise ValueError("Rendered samples must contain a target message or a low_level-stream message.")
+    if not target_indices:
+        raise ValueError("Rendered samples must contain at least one target message.")
     for idx in target_indices:
         if idx < 0 or idx >= len(messages):
             raise ValueError(f"Target message index {idx} is out of bounds.")
+    # ``stream`` is enforced non-None at MessageTurn construction time
+    # (see ``MessageTurn.__post_init__``), so a missing stream here would
+    # mean the dataclass invariant was bypassed; no need to re-check.
 
 
 def _nth_relative(

src/lerobot/policies/gaussian_actor/configuration_gaussian_actor.py

@@ -37,19 +37,13 @@ def is_image_feature(key: str) -> bool:
 @dataclass
 class ConcurrencyConfig:
     """Configuration for the concurrency of the actor and learner.
-
     Possible values are:
     - "threads": Use threads for the actor and learner.
     - "processes": Use processes for the actor and learner.
-
-    ``multiprocessing_context`` selects the process-wide start method when
-    processes are used. Set it to ``None`` to preserve Python's default or a
-    method already selected by the embedding application.
     """
 
     actor: str = "threads"
     learner: str = "threads"
-    multiprocessing_context: str | None = "spawn"
 
 
 @dataclass

src/lerobot/processor/batch_processor.py

@@ -175,6 +175,9 @@ class AddBatchDimensionComplementaryDataStep(ComplementaryDataProcessorStep):
             if isinstance(task_index_value, Tensor) and task_index_value.dim() == 0:
                 complementary_data["task_index"] = task_index_value.unsqueeze(0)
 
+        complementary_data.pop("language_persistent", None)
+        complementary_data.pop("language_events", None)
+
         if "messages" in complementary_data:
             messages = complementary_data["messages"]
             if isinstance(messages, list) and (not messages or isinstance(messages[0], dict)):

src/lerobot/processor/delta_action_processor.py

@@ -132,20 +132,10 @@ class MapDeltaActionToRobotActionStep(RobotActionProcessorStep):
     def transform_features(
         self, features: dict[PipelineFeatureType, dict[str, PolicyFeature]]
     ) -> dict[PipelineFeatureType, dict[str, PolicyFeature]]:
-        for axis in ["x", "y", "z"]:
+        for axis in ["x", "y", "z", "gripper"]:
             features[PipelineFeatureType.ACTION].pop(f"delta_{axis}", None)
-        features[PipelineFeatureType.ACTION].pop("gripper", None)
 
-        for feat in [
-            "enabled",
-            "target_x",
-            "target_y",
-            "target_z",
-            "target_wx",
-            "target_wy",
-            "target_wz",
-            "gripper_vel",
-        ]:
+        for feat in ["enabled", "target_x", "target_y", "target_z", "target_wx", "target_wy", "target_wz"]:
             features[PipelineFeatureType.ACTION][f"{feat}"] = PolicyFeature(
                 type=FeatureType.ACTION, shape=(1,)
             )

src/lerobot/processor/pipeline.py

@@ -41,7 +41,7 @@ from pathlib import Path
 from typing import Any, TypedDict, TypeVar, cast
 
 import torch
-from huggingface_hub import hf_hub_download, snapshot_download
+from huggingface_hub import hf_hub_download
 from safetensors.torch import load_file, save_file
 
 from lerobot.configs import PipelineFeatureType, PolicyFeature
@@ -205,10 +205,6 @@ class ProcessorStep(ABC):
         """
         return None
 
-    def save_artifacts(self, save_directory: Path) -> dict[str, str]:
-        """Save non-tensor assets and map constructor arguments to relative paths."""
-        return {}
-
     def reset(self) -> None:
         """Resets the internal state of the processor step, if any."""
         return None
@@ -553,22 +549,6 @@ class DataProcessorPipeline[TInput, TOutput](HubMixin):
         pipeline_config = self.get_config()
         pipeline_state_dict = self.state_dict()
 
-        for processor_step, step_entry in zip(self.steps, pipeline_config["steps"], strict=True):
-            artifacts = processor_step.save_artifacts(save_directory)
-            if artifacts:
-                for config_key, relative_path in artifacts.items():
-                    artifact_path = Path(relative_path)
-                    if artifact_path.is_absolute() or ".." in artifact_path.parts:
-                        raise ValueError(
-                            f"Processor artifact path must be relative to the checkpoint: {relative_path!r}"
-                        )
-                    if not (save_directory / artifact_path).exists():
-                        raise FileNotFoundError(
-                            f"Processor step did not save declared artifact '{relative_path}'"
-                        )
-                    step_entry["config"][config_key] = artifact_path.as_posix()
-                step_entry["artifacts"] = artifacts
-
         for state_key, step_state_dict in pipeline_state_dict.items():
             state_filename = f"{state_key}.safetensors"
             save_file(step_state_dict, save_directory / state_filename)
@@ -753,13 +733,7 @@ class DataProcessorPipeline[TInput, TOutput](HubMixin):
 
         # 3. Build steps with overrides
         steps, validated_overrides = cls._build_steps_with_overrides(
-            loaded_config,
-            overrides or {},
-            model_id,
-            base_path,
-            config_filename,
-            hub_download_kwargs,
-            is_local_source,
+            loaded_config, overrides or {}, model_id, base_path, hub_download_kwargs, is_local_source
         )
 
         # 4. Validate that all overrides were used
@@ -948,7 +922,6 @@ class DataProcessorPipeline[TInput, TOutput](HubMixin):
         overrides: dict[str, Any],
         model_id: str,
         base_path: Path | None,
-        config_filename: str,
         hub_download_kwargs: dict[str, Any],
         is_local_source: bool = False,
     ) -> tuple[list[ProcessorStep], set[str]]:
@@ -1003,68 +976,15 @@ class DataProcessorPipeline[TInput, TOutput](HubMixin):
             ImportError: If a step class cannot be imported or found in registry
             ValueError: If a step cannot be instantiated with its configuration
         """
-        loaded_config = deepcopy(loaded_config)
-        cls._resolve_artifact_paths(
-            loaded_config,
-            model_id,
-            base_path,
-            config_filename,
-            hub_download_kwargs,
-        )
         steps, remaining_override_keys = cls._build_steps_from_config(loaded_config, overrides)
 
         for step_instance, step_entry in zip(steps, loaded_config["steps"], strict=True):
             cls._load_step_state(
-                step_instance,
-                step_entry,
-                model_id,
-                base_path,
-                config_filename,
-                hub_download_kwargs,
-                is_local_source,
+                step_instance, step_entry, model_id, base_path, hub_download_kwargs, is_local_source
             )
 
         return steps, remaining_override_keys
 
-    @classmethod
-    def _resolve_artifact_paths(
-        cls,
-        loaded_config: dict[str, Any],
-        model_id: str,
-        base_path: Path | None,
-        config_filename: str,
-        hub_download_kwargs: dict[str, Any],
-    ) -> None:
-        """Resolve declared relative processor artifacts before step construction."""
-        is_local = Path(model_id).is_dir() or Path(model_id).is_file()
-
-        for step_entry in loaded_config["steps"]:
-            artifacts = step_entry.get("artifacts", {})
-            for config_key, relative_path in artifacts.items():
-                artifact_path = Path(relative_path)
-                if artifact_path.is_absolute() or ".." in artifact_path.parts:
-                    raise ValueError(
-                        f"Processor artifact path must be relative to the checkpoint: {relative_path!r}"
-                    )
-
-                resolved_path = base_path / artifact_path if base_path is not None else artifact_path
-                if not resolved_path.exists() and not is_local:
-                    repository_path = Path(config_filename).parent / artifact_path
-                    snapshot_download(
-                        repo_id=model_id,
-                        repo_type="model",
-                        allow_patterns=f"{repository_path.as_posix()}/**",
-                        **hub_download_kwargs,
-                    )
-
-                if not resolved_path.exists():
-                    step_name = step_entry.get("registry_name", step_entry.get("class", "unknown"))
-                    raise FileNotFoundError(
-                        f"Missing processor artifact '{relative_path}' for step '{step_name}' "
-                        f"next to '{config_filename}'. Checkpoint artifacts are incomplete."
-                    )
-                step_entry["config"][config_key] = str(resolved_path)
-
     @classmethod
     def _build_steps_from_config(
         cls,
@@ -1224,7 +1144,6 @@ class DataProcessorPipeline[TInput, TOutput](HubMixin):
         step_entry: dict[str, Any],
         model_id: str,
         base_path: Path | None,
-        config_filename: str,
         hub_download_kwargs: dict[str, Any],
         is_local_source: bool = False,
     ) -> None:
@@ -1290,7 +1209,7 @@ class DataProcessorPipeline[TInput, TOutput](HubMixin):
             # Download from Hub
             state_path = hf_hub_download(
                 repo_id=model_id,
-                filename=(Path(config_filename).parent / state_filename).as_posix(),
+                filename=state_filename,
                 repo_type="model",
                 **hub_download_kwargs,
             )

src/lerobot/processor/render_messages_processor.py

@@ -16,7 +16,7 @@
 
 from __future__ import annotations
 
-from dataclasses import asdict, dataclass
+from dataclasses import dataclass
 from typing import Any
 
 from lerobot.configs import PipelineFeatureType, PolicyFeature
@@ -32,18 +32,17 @@ from .pipeline import ProcessorStep, ProcessorStepRegistry
 @dataclass
 @ProcessorStepRegistry.register(name="render_messages_processor")
 class RenderMessagesStep(ProcessorStep):
-    """Render language columns into recipe-defined messages and supervision metadata."""
+    """Processor step that turns raw language columns into rendered chat messages.
+
+    Reads ``language_persistent`` and ``language_events`` from the transition's
+    complementary data, renders them through ``recipe`` at the sample timestamp,
+    and replaces the raw columns with the resulting ``messages`` /
+    ``message_streams`` / ``target_message_indices`` keys.
+    """
 
     recipe: TrainingRecipe
     dataset_ctx: Any | None = None
 
-    def __post_init__(self) -> None:
-        if isinstance(self.recipe, dict):
-            self.recipe = TrainingRecipe.from_dict(self.recipe)
-
-    def get_config(self) -> dict[str, Any]:
-        return {"recipe": asdict(self.recipe)}
-
     def __call__(self, transition: EnvTransition) -> EnvTransition | None:
         """Render messages for a single transition; return ``None`` to drop it."""
         complementary_data = transition.get(TransitionKey.COMPLEMENTARY_DATA) or {}
@@ -51,17 +50,7 @@ class RenderMessagesStep(ProcessorStep):
         events = complementary_data.get(LANGUAGE_EVENTS) or []
 
         if not persistent and not events:
-            rendered = _fallback_low_level_render(complementary_data.get("task"))
-            if rendered is None:
-                return transition
-            new_transition = transition.copy()
-            new_complementary_data = dict(new_transition.get(TransitionKey.COMPLEMENTARY_DATA) or {})
-            new_complementary_data.update(rendered)
-            new_transition[TransitionKey.COMPLEMENTARY_DATA] = new_complementary_data
-            return new_transition
-
-        if _is_batched_language(persistent) or _is_batched_language(events):
-            return self._call_batch(transition, complementary_data, persistent, events)
+            return transition
 
         timestamp = complementary_data.get("timestamp")
         if timestamp is None:
@@ -78,147 +67,18 @@ class RenderMessagesStep(ProcessorStep):
             dataset_ctx=self.dataset_ctx,
         )
         if rendered is None:
-            rendered = _fallback_low_level_render(complementary_data.get("task"))
-            if rendered is None:
-                return None
+            return None
 
         new_transition = transition.copy()
-        new_complementary_data = dict(new_transition.get(TransitionKey.COMPLEMENTARY_DATA) or {})
+        new_complementary_data = dict(complementary_data)
         new_complementary_data.pop(LANGUAGE_PERSISTENT, None)
         new_complementary_data.pop(LANGUAGE_EVENTS, None)
         new_complementary_data.update(rendered)
         new_transition[TransitionKey.COMPLEMENTARY_DATA] = new_complementary_data
         return new_transition
 
-    def _call_batch(
-        self,
-        transition: EnvTransition,
-        complementary_data: dict[str, Any],
-        persistent_batch: list,
-        events_batch: list,
-    ) -> EnvTransition | None:
-        timestamp = complementary_data.get("timestamp")
-        if timestamp is None:
-            raise KeyError("RenderMessagesStep requires sample timestamp in complementary data.")
-
-        batch_size = max(len(persistent_batch), len(events_batch))
-        messages: list[list[dict[str, Any]]] = []
-        message_streams: list[list[str | None]] = []
-        target_message_indices: list[list[int]] = []
-        keep_indices: list[int] = []
-
-        for i in range(batch_size):
-            rendered = render_sample(
-                recipe=self.recipe,
-                persistent=persistent_batch[i] if i < len(persistent_batch) else [],
-                events=events_batch[i] if i < len(events_batch) else [],
-                t=_batch_value(timestamp, i),
-                sample_idx=int(_batch_value(complementary_data.get("index", 0), i)),
-                task=_batch_value(complementary_data.get("task"), i),
-                dataset_ctx=self.dataset_ctx,
-            )
-            if rendered is None:
-                rendered = _fallback_low_level_render(_batch_value(complementary_data.get("task"), i))
-                if rendered is None:
-                    continue
-            keep_indices.append(i)
-            messages.append(rendered["messages"])
-            message_streams.append(rendered["message_streams"])
-            target_message_indices.append(rendered["target_message_indices"])
-
-        if not messages:
-            return None
-
-        new_transition = (
-            _select_batch_indices(transition, keep_indices)
-            if len(keep_indices) != batch_size
-            else transition.copy()
-        )
-        new_complementary_data = dict(new_transition.get(TransitionKey.COMPLEMENTARY_DATA) or {})
-        new_complementary_data.pop(LANGUAGE_PERSISTENT, None)
-        new_complementary_data.pop(LANGUAGE_EVENTS, None)
-        new_complementary_data["messages"] = messages
-        new_complementary_data["message_streams"] = message_streams
-        new_complementary_data["target_message_indices"] = target_message_indices
-        new_transition[TransitionKey.COMPLEMENTARY_DATA] = new_complementary_data
-        return new_transition
-
     def transform_features(
         self, features: dict[PipelineFeatureType, dict[str, PolicyFeature]]
     ) -> dict[PipelineFeatureType, dict[str, PolicyFeature]]:
         """Pass features through unchanged; rendering only touches complementary data."""
         return features
-
-
-def _scalar(value: Any) -> float | int:
-    """Unwrap a tensor/array/single-element list into a Python scalar."""
-    if hasattr(value, "item"):
-        return value.item()
-    if isinstance(value, list):
-        if len(value) != 1:
-            raise ValueError(f"Expected a scalar, got list of length {len(value)}: {value!r}")
-        return _scalar(value[0])
-    return value
-
-
-def _is_batched_language(value: Any) -> bool:
-    return isinstance(value, list) and bool(value) and isinstance(value[0], list)
-
-
-def _batch_value(value: Any, index: int) -> Any:
-    if value is None:
-        return None
-    if isinstance(value, list):
-        return value[index]
-    if hasattr(value, "ndim") and value.ndim > 0:
-        return _scalar(value[index])
-    return _scalar(value)
-
-
-def _select_batch_indices(transition: EnvTransition, indices: list[int]) -> EnvTransition:
-    selected = transition.copy()
-    for key in (TransitionKey.OBSERVATION, TransitionKey.COMPLEMENTARY_DATA):
-        data = selected.get(key)
-        if isinstance(data, dict):
-            selected[key] = {k: _select_value(v, indices) for k, v in data.items()}
-    action = selected.get(TransitionKey.ACTION)
-    if action is not None:
-        selected[TransitionKey.ACTION] = _select_value(action, indices)
-    return selected
-
-
-def _select_value(value: Any, indices: list[int]) -> Any:
-    if isinstance(value, list) and len(value) >= len(indices):
-        return [value[i] for i in indices]
-    if hasattr(value, "index_select") and hasattr(value, "new_tensor") and getattr(value, "ndim", 0) > 0:
-        return value.index_select(0, value.new_tensor(indices).long())
-    return value
-
-
-def _fallback_low_level_render(task: Any) -> dict[str, Any] | None:
-    """Keep action-only samples trainable when no recipe branch matches."""
-    if hasattr(task, "item"):
-        task = task.item()
-    if isinstance(task, list):
-        messages = []
-        message_streams = []
-        target_message_indices = []
-        for t in task:
-            rendered = _fallback_low_level_render(t)
-            if rendered is None:
-                return None
-            messages.append(rendered["messages"])
-            message_streams.append(rendered["message_streams"])
-            target_message_indices.append(rendered["target_message_indices"])
-        return {
-            "messages": messages,
-            "message_streams": message_streams,
-            "target_message_indices": target_message_indices,
-        }
-    if not isinstance(task, str) or not task:
-        return None
-    return {
-        "messages": [{"role": "user", "content": task}],
-        "message_streams": ["low_level"],
-        "target_message_indices": [],
-    }

src/lerobot/processor/tokenizer_processor.py

@@ -25,7 +25,6 @@ from __future__ import annotations
 
 import logging
 from dataclasses import dataclass, field
-from pathlib import Path
 from typing import TYPE_CHECKING, Any
 
 import torch
@@ -33,7 +32,6 @@ import torch
 from lerobot.configs import FeatureType, PipelineFeatureType, PolicyFeature
 from lerobot.types import EnvTransition, RobotObservation, TransitionKey
 from lerobot.utils.constants import (
-    ACTION_CODE_TOKEN_MASK,
     ACTION_TOKEN_MASK,
     ACTION_TOKENS,
     OBS_LANGUAGE_ATTENTION_MASK,
@@ -138,7 +136,7 @@ class TokenizerProcessorStep(ObservationProcessorStep):
         # Standardize to a list of strings for the tokenizer
         if isinstance(task, str):
             return [task]
-        elif isinstance(task, list | tuple) and all(isinstance(t, str) for t in task):
+        elif isinstance(task, (list, tuple)) and all(isinstance(t, str) for t in task):
             return list(task)
 
         return None
@@ -351,7 +349,6 @@ class ActionTokenizerProcessorStep(ActionProcessorStep):
     max_action_tokens: int = 256
     fast_skip_tokens: int = 128
     paligemma_tokenizer_name: str = "google/paligemma-3b-pt-224"
-    allow_truncation: bool = True
     # Internal tokenizer instance (not part of the config)
     action_tokenizer: Any = field(default=None, init=False, repr=False)
     _paligemma_tokenizer: Any = field(default=None, init=False, repr=False)
@@ -415,15 +412,14 @@ class ActionTokenizerProcessorStep(ActionProcessorStep):
             # During inference, no action is available, skip tokenization
             return new_transition
 
-        # Tokenize and get masks for the full formatted sequence and the discrete action codes.
-        tokens, mask, code_mask = self._tokenize_action(action)
+        # Tokenize and get both tokens and mask
+        tokens, mask = self._tokenize_action(action)
 
         # Store mask in complementary data
         complementary_data = new_transition.get(TransitionKey.COMPLEMENTARY_DATA, {})
         if complementary_data is None:
             complementary_data = {}
         complementary_data[ACTION_TOKEN_MASK] = mask
-        complementary_data[ACTION_CODE_TOKEN_MASK] = code_mask
         complementary_data[ACTION_TOKENS] = tokens
         new_transition[TransitionKey.COMPLEMENTARY_DATA] = complementary_data
         return new_transition
@@ -434,7 +430,7 @@ class ActionTokenizerProcessorStep(ActionProcessorStep):
         """
         return self._paligemma_tokenizer.vocab_size - 1 - self.fast_skip_tokens - tokens
 
-    def _tokenize_action(self, action: torch.Tensor) -> tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
+    def _tokenize_action(self, action: torch.Tensor) -> tuple[torch.Tensor, torch.Tensor]:
         """
         Tokenizes the action tensor and creates a mask.
 
@@ -463,7 +459,6 @@ class ActionTokenizerProcessorStep(ActionProcessorStep):
         # The fast tokenizer expects action data and returns token IDs
         tokens_list = []
         masks_list = []
-        code_masks_list = []
 
         for i in range(batch_size):
             # Tokenize single action (move to CPU first as tokenizer uses scipy which requires numpy)
@@ -481,82 +476,65 @@ class ActionTokenizerProcessorStep(ActionProcessorStep):
             if tokens.dim() > 1:
                 tokens = tokens.flatten()
 
-            action_code_tokens = self._act_tokens_to_paligemma_tokens(tokens)
             bos_id = self._paligemma_tokenizer.bos_token_id
-            prompt_tokens = torch.tensor(
-                self._paligemma_tokenizer.encode("Action: ", add_special_tokens=False),
-                device=action.device,
-            )
-            end_tokens = torch.tensor(self._paligemma_tokenizer.encode("|"), device=action.device)
-
-            code_start = 1 + len(prompt_tokens)
-            code_end = code_start + len(action_code_tokens)
+            # add bos
             tokens = torch.cat(
                 [
                     torch.tensor([bos_id], device=action.device),
-                    prompt_tokens,
-                    action_code_tokens,
-                    end_tokens,
+                    torch.tensor(
+                        self._paligemma_tokenizer.encode("Action: ", add_special_tokens=False),
+                        device=action.device,
+                    ),
+                    self._act_tokens_to_paligemma_tokens(tokens),
+                    torch.tensor(self._paligemma_tokenizer.encode("|"), device=action.device),
                 ]
             )
-            code_mask = torch.zeros(len(tokens), dtype=torch.bool, device=action.device)
-            code_mask[code_start:code_end] = True
 
             # Truncate or pad to max_action_tokens
             if len(tokens) > self.max_action_tokens:
-                if not self.allow_truncation:
-                    raise ValueError(
-                        f"FAST action sequence has {len(tokens)} tokens, exceeding "
-                        f"max_action_tokens={self.max_action_tokens}."
-                    )
                 logging.warning(
                     f"Token length ({len(tokens)}) exceeds max length ({self.max_action_tokens}), truncating. "
                     "Consider increasing the `max_action_tokens` in your model config if this happens frequently."
                 )
                 tokens = tokens[: self.max_action_tokens]
-                code_mask = code_mask[: self.max_action_tokens]
                 mask = torch.ones(self.max_action_tokens, dtype=torch.bool, device=action.device)
             else:
-                pad_len = self.max_action_tokens - len(tokens)
                 mask = torch.cat(
                     [
                         torch.ones(len(tokens), dtype=torch.bool, device=action.device),
-                        torch.zeros(pad_len, dtype=torch.bool, device=action.device),
+                        torch.zeros(
+                            self.max_action_tokens - len(tokens), dtype=torch.bool, device=action.device
+                        ),
                     ]
                 )
-                code_mask = torch.nn.functional.pad(code_mask, (0, pad_len), value=False)
                 # Pad tokens with zeros
-                tokens = torch.nn.functional.pad(tokens, (0, pad_len), value=0)
+                tokens = torch.nn.functional.pad(tokens, (0, self.max_action_tokens - len(tokens)), value=0)
 
             tokens_list.append(tokens)
             masks_list.append(mask)
-            code_masks_list.append(code_mask)
 
         # Stack into batched tensors
         tokens_batch = torch.stack(tokens_list, dim=0)  # (B, max_action_tokens)
         masks_batch = torch.stack(masks_list, dim=0)  # (B, max_action_tokens)
-        code_masks_batch = torch.stack(code_masks_list, dim=0)  # (B, max_action_tokens)
 
         # Remove batch dimension if input was single sample
         if single_sample:
             tokens_batch = tokens_batch.squeeze(0)
             masks_batch = masks_batch.squeeze(0)
-            code_masks_batch = code_masks_batch.squeeze(0)
 
         # Move to the same device as the input
         if device is not None:
             tokens_batch = tokens_batch.to(device)
             masks_batch = masks_batch.to(device)
-            code_masks_batch = code_masks_batch.to(device)
 
-        return tokens_batch, masks_batch, code_masks_batch
+        return tokens_batch, masks_batch
 
     def action(self, action: torch.Tensor) -> torch.Tensor:
         """
         This method is not used since we override __call__.
         Required by ActionProcessorStep ABC.
         """
-        tokens, _, _ = self._tokenize_action(action)
+        tokens, _ = self._tokenize_action(action)
         return tokens
 
     def get_config(self) -> dict[str, Any]:
@@ -572,9 +550,6 @@ class ActionTokenizerProcessorStep(ActionProcessorStep):
         config = {
             "trust_remote_code": self.trust_remote_code,
             "max_action_tokens": self.max_action_tokens,
-            "fast_skip_tokens": self.fast_skip_tokens,
-            "paligemma_tokenizer_name": self.paligemma_tokenizer_name,
-            "allow_truncation": self.allow_truncation,
         }
 
         # Only save tokenizer_name if it was used to create the tokenizer
@@ -583,14 +558,6 @@ class ActionTokenizerProcessorStep(ActionProcessorStep):
 
         return config
 
-    def save_artifacts(self, save_directory: Path) -> dict[str, str]:
-        artifact_path = Path("action_tokenizer")
-        save_pretrained = getattr(self.action_tokenizer, "save_pretrained", None)
-        if save_pretrained is None:
-            raise TypeError("Action tokenizer must implement save_pretrained() to save a portable pipeline.")
-        save_pretrained(save_directory / artifact_path)
-        return {"action_tokenizer_name": artifact_path.as_posix()}
-
     def transform_features(
         self, features: dict[PipelineFeatureType, dict[str, PolicyFeature]]
     ) -> dict[PipelineFeatureType, dict[str, PolicyFeature]]:

src/lerobot/rl/actor.py

@@ -91,7 +91,7 @@ from lerobot.robots import so_follower  # noqa: F401
 from lerobot.teleoperators import gamepad, so_leader  # noqa: F401
 from lerobot.teleoperators.utils import TeleopEvents
 from lerobot.utils.device_utils import get_safe_torch_device
-from lerobot.utils.process import ProcessSignalHandler, ensure_multiprocessing_start_method
+from lerobot.utils.process import ProcessSignalHandler
 from lerobot.utils.random_utils import set_seed
 from lerobot.utils.robot_utils import precise_sleep
 from lerobot.utils.transition import (
@@ -124,7 +124,9 @@ def actor_cli(cfg: TrainRLServerPipelineConfig):
     cfg.validate()
     display_pid = False
     if not use_threads(cfg):
-        ensure_multiprocessing_start_method(cfg.policy.concurrency.multiprocessing_context)
+        import torch.multiprocessing as mp
+
+        mp.set_start_method("spawn")
         display_pid = True
 
     # Create logs directory to ensure it exists

src/lerobot/rl/learner.py

@@ -102,7 +102,7 @@ from lerobot.utils.constants import (
 )
 from lerobot.utils.device_utils import get_safe_torch_device
 from lerobot.utils.io_utils import load_json, write_json
-from lerobot.utils.process import ProcessSignalHandler, ensure_multiprocessing_start_method
+from lerobot.utils.process import ProcessSignalHandler
 from lerobot.utils.random_utils import set_seed
 from lerobot.utils.utils import (
     format_big_number,
@@ -123,7 +123,9 @@ def train_cli(cfg: TrainRLServerPipelineConfig):
     # Fail fast with a friendly error if the optional ``hilserl`` extra is missing.
     require_package("grpcio", extra="hilserl", import_name="grpc")
     if not use_threads(cfg):
-        ensure_multiprocessing_start_method(cfg.policy.concurrency.multiprocessing_context)
+        import torch.multiprocessing as mp
+
+        mp.set_start_method("spawn")
 
     # Use the job_name from the config
     train(

src/lerobot/utils/collate.py

@@ -22,7 +22,7 @@ from torch.utils.data._utils.collate import default_collate
 
 from lerobot.datasets.language import LANGUAGE_COLUMNS
 
-_PYTHON_LIST_KEYS = {"messages", "message_streams", "target_message_indices", *LANGUAGE_COLUMNS}
+_PYTHON_LIST_KEYS = {"messages", "message_streams", "target_message_indices"}
 
 
 def lerobot_collate_fn(batch: list[dict[str, Any] | None]) -> dict[str, Any] | None:

src/lerobot/utils/constants.py

@@ -26,7 +26,6 @@ OBS_IMAGES = OBS_IMAGE + "s"
 OBS_LANGUAGE = OBS_STR + ".language"
 OBS_LANGUAGE_TOKENS = OBS_LANGUAGE + ".tokens"
 OBS_LANGUAGE_ATTENTION_MASK = OBS_LANGUAGE + ".attention_mask"
-OBS_LANGUAGE_CAUSAL_MARKS = OBS_LANGUAGE + ".causal_marks"
 OBS_LANGUAGE_SUBTASK = OBS_STR + ".subtask"
 OBS_LANGUAGE_SUBTASK_TOKENS = OBS_LANGUAGE_SUBTASK + ".tokens"
 OBS_LANGUAGE_SUBTASK_ATTENTION_MASK = OBS_LANGUAGE_SUBTASK + ".attention_mask"
@@ -35,7 +34,6 @@ ACTION = "action"
 ACTION_PREFIX = ACTION + "."
 ACTION_TOKENS = ACTION + ".tokens"
 ACTION_TOKEN_MASK = ACTION + ".token_mask"
-ACTION_CODE_TOKEN_MASK = ACTION + ".code_token_mask"
 REWARD = "next.reward"
 TRUNCATED = "next.truncated"
 DONE = "next.done"

src/lerobot/utils/process.py

@@ -16,39 +16,11 @@
 # limitations under the License.
 
 import logging
-import multiprocessing
 import os
 import signal
 import sys
 
 
-def ensure_multiprocessing_start_method(start_method: str | None) -> None:
-    """Set a multiprocessing start method once, or verify the existing method matches.
-
-    Passing ``None`` leaves Python's process-wide default untouched. This is useful
-    when LeRobot is embedded in an application that owns multiprocessing setup.
-    """
-    if start_method is None:
-        return
-
-    available_methods = multiprocessing.get_all_start_methods()
-    if start_method not in available_methods:
-        raise ValueError(
-            f"Multiprocessing start method must be one of {available_methods} on this platform, "
-            f"got {start_method!r}."
-        )
-
-    current_method = multiprocessing.get_start_method(allow_none=True)
-    if current_method is None:
-        multiprocessing.set_start_method(start_method)
-    elif current_method != start_method:
-        raise RuntimeError(
-            f"Multiprocessing start method is already {current_method!r}; cannot change it to "
-            f"{start_method!r}. Set the configured multiprocessing context to null to keep the "
-            "application's existing method, or launch LeRobot in a fresh process."
-        )
-
-
 class ProcessSignalHandler:
     """Utility class to attach graceful shutdown signal handlers.
 

tests/configs/test_recipe.py

@@ -29,13 +29,6 @@ def test_message_recipe_validates_unknown_binding():
         )
 
 
-def test_canonical_recipe_loads():
-    """The canonical PI052 blend YAML loads + validates."""
-    recipe = TrainingRecipe.from_yaml(Path("src/lerobot/configs/recipes/subtask_mem_vqa_speech.yaml"))
-    assert recipe.blend is not None
-    assert sum(c.weight for c in recipe.blend.values()) == pytest.approx(1.0)
-
-
 def test_message_turn_requires_a_stream():
     """Every turn must declare a stream — None is rejected at construction.
 

tests/datasets/test_language_render.py

@@ -343,84 +343,6 @@ def test_resolve_task_explicit_override_beats_rephrasings():
     assert rendered["messages"][0]["content"] == "explicit override wins"
 
 
-def test_flow_only_low_level_recipe_renders_without_target():
-    """Regression: a flow-only ``low_level`` recipe has no ``target`` turn —
-    its supervision is the action-expert flow loss, not text-CE. It must
-    still render (not ``None``), otherwise every blend draw of it is dropped
-    and the action expert never receives a flow loss."""
-    recipe = TrainingRecipe(
-        messages=[
-            MessageTurn(
-                role="user",
-                content="${subtask}",
-                stream="low_level",
-                if_present="subtask",
-            ),
-        ],
-        bindings={"subtask": "active_at(t, style=subtask)"},
-    )
-
-    rendered = render_sample(
-        recipe=recipe,
-        persistent=PERSISTENT,
-        events=[],
-        t=0.5,
-        sample_idx=0,
-        task="clean kitchen",
-    )
-
-    assert rendered is not None
-    assert rendered["messages"] == [{"role": "user", "content": "subtask 0"}]
-    assert rendered["message_streams"] == ["low_level"]
-    assert rendered["target_message_indices"] == []
-
-
-def test_vqa_frame_is_consumed_over_the_weighted_blend():
-    """A frame carrying a VQA annotation renders the ``ask_vqa*`` sub-recipe
-    even when its blend weight is tiny — VQA annotations are sparse and must
-    never be wasted on a subtask/action draw."""
-    recipe = TrainingRecipe(
-        blend={
-            "high_level_subtask": TrainingRecipe(
-                weight=0.99,
-                messages=[
-                    MessageTurn(role="user", content="${task}", stream="high_level"),
-                    MessageTurn(role="assistant", content="a subtask", stream="high_level", target=True),
-                ],
-            ),
-            "ask_vqa_top": TrainingRecipe(
-                weight=0.01,
-                bindings={
-                    "vqa_query": "emitted_at(t, style=vqa, role=user, camera=observation.images.top)",
-                    "vqa": "emitted_at(t, style=vqa, role=assistant, camera=observation.images.top)",
-                },
-                messages=[
-                    MessageTurn(
-                        role="user", content="${vqa_query}", stream="high_level", if_present="vqa_query"
-                    ),
-                    MessageTurn(
-                        role="assistant",
-                        content="${vqa}",
-                        stream="high_level",
-                        target=True,
-                        if_present="vqa",
-                    ),
-                ],
-            ),
-        }
-    )
-    # A frame WITH a vqa event renders VQA on every sample_idx, despite the
-    # ask_vqa weight being only 0.01.
-    for sample_idx in range(20):
-        rendered = render_sample(
-            recipe=recipe, persistent=PERSISTENT, events=EVENTS_AT_1, t=1.0, sample_idx=sample_idx, task="x"
-        )
-        assert rendered["messages"][-1]["content"] == '{"count": 2}', sample_idx
-    # A frame WITHOUT a vqa event falls back to the normal weighted blend.
-    rendered = render_sample(recipe=recipe, persistent=PERSISTENT, events=[], t=1.0, sample_idx=0, task="x")
-    assert rendered["messages"][-1]["content"] == "a subtask"
-
-
 def test_emitted_at_persistent_tolerates_small_timestamp_drift():
     """Persistent ``emitted_at`` should match within EMITTED_AT_TOLERANCE_S
     so callers that derive ``t`` arithmetically (``frame_idx / fps``) still

tests/datasets/test_sampler.py

@@ -25,7 +25,7 @@ from datasets import Dataset  # noqa: E402
 from lerobot.datasets.io_utils import (
     hf_transform_to_torch,
 )
-from lerobot.datasets.sampler import EpisodeAwareSampler, compute_sampler_state
+from lerobot.datasets.sampler import EpisodeAwareSampler
 
 
 def calculate_episode_data_index(hf_dataset: Dataset) -> dict[str, torch.Tensor]:
@@ -154,6 +154,8 @@ def test_partial_episode_drop_warns(caplog):
 
 # --- seeded (seed, epoch) shuffling, resume, and state ---
 
+from lerobot.datasets.sampler import compute_sampler_state  # noqa: E402
+
 EPISODE_BOUNDS = ([0, 2, 3], [2, 3, 6])  # episodes of 2, 1 and 3 frames
 
 

tests/policies/test_gaussian_actor_config.py

@@ -113,7 +113,6 @@ def test_gaussian_actor_config_default_initialization():
     # Concurrency configuration
     assert config.concurrency.actor == "threads"
     assert config.concurrency.learner == "threads"
-    assert config.concurrency.multiprocessing_context == "spawn"
 
     assert isinstance(config.actor_network_kwargs, ActorNetworkConfig)
     assert isinstance(config.policy_kwargs, PolicyConfig)
@@ -153,7 +152,6 @@ def test_concurrency_config():
     config = ConcurrencyConfig()
     assert config.actor == "threads"
     assert config.learner == "threads"
-    assert config.multiprocessing_context == "spawn"
 
 
 def test_gaussian_actor_config_custom_initialization():

tests/processor/test_render_messages_processor.py

@@ -12,9 +12,7 @@ from lerobot.processor.render_messages_processor import RenderMessagesStep  # no
 from lerobot.types import TransitionKey  # noqa: E402
 
 
-def test_render_messages_step_renders_task_fallback_without_language_columns():
-    """No language columns + a task string → low-level task fallback render,
-    matching what the policy sees at eval time on unannotated observations."""
+def test_render_messages_step_noops_without_language_columns():
     recipe = TrainingRecipe(
         messages=[
             MessageTurn(role="user", content="${task}", stream="high_level"),
@@ -23,24 +21,6 @@ def test_render_messages_step_renders_task_fallback_without_language_columns():
     )
     transition = create_transition(complementary_data={"task": "do it"})
 
-    out = RenderMessagesStep(recipe)(transition)
-    data = out[TransitionKey.COMPLEMENTARY_DATA]
-
-    assert data["messages"] == [{"role": "user", "content": "do it"}]
-    assert data["message_streams"] == ["low_level"]
-    assert data["target_message_indices"] == []
-    assert data["task"] == "do it"
-
-
-def test_render_messages_step_noops_without_language_columns_or_task():
-    recipe = TrainingRecipe(
-        messages=[
-            MessageTurn(role="user", content="${task}", stream="high_level"),
-            MessageTurn(role="assistant", content="${subtask}", stream="low_level", target=True),
-        ]
-    )
-    transition = create_transition(complementary_data={})
-
     assert RenderMessagesStep(recipe)(transition) == transition
 
 
@@ -78,70 +58,3 @@ def test_render_messages_step_renders_and_drops_raw_language():
     assert data["messages"][-1]["content"] == "reach carefully"
     assert data["message_streams"] == ["high_level", "low_level"]
     assert data["target_message_indices"] == [1]
-
-
-def test_render_messages_step_falls_back_to_low_level_task_when_recipe_misses():
-    recipe = TrainingRecipe(
-        messages=[
-            MessageTurn(
-                role="assistant",
-                content="${subtask}",
-                stream="high_level",
-                target=True,
-                if_present="subtask",
-            ),
-        ]
-    )
-    transition = create_transition(
-        complementary_data={
-            "task": "pick the cube",
-            "timestamp": torch.tensor(0.0),
-            "index": torch.tensor(7),
-            "language_persistent": [],
-            "language_events": [{"style": "unmatched", "timestamp": 0.0}],
-        }
-    )
-
-    out = RenderMessagesStep(recipe)(transition)
-    data = out[TransitionKey.COMPLEMENTARY_DATA]
-
-    assert data["messages"] == [{"role": "user", "content": "pick the cube"}]
-    assert data["message_streams"] == ["low_level"]
-    assert data["target_message_indices"] == []
-
-
-def test_render_messages_step_falls_back_per_sample_in_batched_language():
-    recipe = TrainingRecipe(
-        messages=[
-            MessageTurn(
-                role="assistant",
-                content="${subtask}",
-                stream="high_level",
-                target=True,
-                if_present="subtask",
-            ),
-        ]
-    )
-    transition = create_transition(
-        action=torch.arange(4).reshape(2, 2),
-        complementary_data={
-            "task": ["pick the cube", "open the drawer"],
-            "timestamp": torch.tensor([0.0, 1.0]),
-            "index": torch.tensor([7, 8]),
-            "language_persistent": [[], []],
-            "language_events": [
-                [{"style": "unmatched", "timestamp": 0.0}],
-                [{"style": "unmatched", "timestamp": 1.0}],
-            ],
-        },
-    )
-
-    out = RenderMessagesStep(recipe)(transition)
-    data = out[TransitionKey.COMPLEMENTARY_DATA]
-
-    assert data["messages"] == [
-        [{"role": "user", "content": "pick the cube"}],
-        [{"role": "user", "content": "open the drawer"}],
-    ]
-    assert data["message_streams"] == [["low_level"], ["low_level"]]
-    assert data["target_message_indices"] == [[], []]

tests/processor/test_tokenizer_processor.py

@@ -25,7 +25,7 @@ import pytest
 import torch
 
 from lerobot.configs.types import FeatureType, PipelineFeatureType, PolicyFeature
-from lerobot.processor import ActionTokenizerProcessorStep, DataProcessorPipeline, TokenizerProcessorStep
+from lerobot.processor import DataProcessorPipeline, TokenizerProcessorStep
 from lerobot.processor.converters import create_transition, identity_transition
 from lerobot.types import TransitionKey
 from lerobot.utils.constants import (
@@ -88,46 +88,6 @@ class MockTokenizer:
         return result
 
 
-def test_action_tokenizer_config_preserves_token_mapping():
-    processor = object.__new__(ActionTokenizerProcessorStep)
-    processor.trust_remote_code = True
-    processor.max_action_tokens = 384
-    processor.fast_skip_tokens = 64
-    processor.paligemma_tokenizer_name = "custom/paligemma"
-    processor.allow_truncation = False
-    processor.action_tokenizer_name = "custom/fast"
-    processor.action_tokenizer_input_object = None
-
-    assert processor.get_config() == {
-        "trust_remote_code": True,
-        "max_action_tokens": 384,
-        "fast_skip_tokens": 64,
-        "paligemma_tokenizer_name": "custom/paligemma",
-        "allow_truncation": False,
-        "action_tokenizer_name": "custom/fast",
-    }
-
-
-def test_action_tokenizer_can_reject_truncated_sequences():
-    processor = object.__new__(ActionTokenizerProcessorStep)
-    processor.max_action_tokens = 4
-    processor.fast_skip_tokens = 128
-    processor.allow_truncation = False
-    processor.action_tokenizer = lambda _actions: [1, 2, 3]
-    processor._paligemma_tokenizer = type(
-        "Tokenizer",
-        (),
-        {
-            "vocab_size": 1000,
-            "bos_token_id": 2,
-            "encode": lambda _self, text, **_kwargs: [10, 11] if text == "Action: " else [12, 1],
-        },
-    )()
-
-    with pytest.raises(ValueError, match="max_action_tokens=4"):
-        processor._tokenize_action(torch.zeros(1, 2, 1))
-
-
 @pytest.fixture
 def mock_tokenizer():
     """Provide a mock tokenizer for testing."""

tests/utils/test_collate.py

@@ -9,7 +9,7 @@ import torch  # noqa: E402
 from lerobot.utils.collate import lerobot_collate_fn  # noqa: E402
 
 
-def test_lerobot_collate_preserves_messages_and_raw_language():
+def test_lerobot_collate_preserves_messages_and_drops_raw_language():
     batch = [
         {
             "index": torch.tensor(0),
@@ -17,14 +17,14 @@ def test_lerobot_collate_preserves_messages_and_raw_language():
             "message_streams": ["low_level"],
             "target_message_indices": [0],
             "language_persistent": [{"content": "raw"}],
-            "language_events": [{"content": "event a"}],
+            "language_events": [],
         },
         {
             "index": torch.tensor(1),
             "messages": [{"role": "assistant", "content": "b"}],
             "message_streams": ["low_level"],
             "target_message_indices": [0],
-            "language_persistent": [{"content": "raw b"}],
+            "language_persistent": [{"content": "raw"}],
             "language_events": [],
         },
     ]
@@ -36,8 +36,8 @@ def test_lerobot_collate_preserves_messages_and_raw_language():
     assert out["messages"][1][0]["content"] == "b"
     assert out["message_streams"] == [["low_level"], ["low_level"]]
     assert out["target_message_indices"] == [[0], [0]]
-    assert out["language_persistent"] == [[{"content": "raw"}], [{"content": "raw b"}]]
-    assert out["language_events"] == [[{"content": "event a"}], []]
+    assert "language_persistent" not in out
+    assert "language_events" not in out
 
 
 def test_lerobot_collate_passes_through_standard_batch():