feat: language annotation pipeline (PR 2/3)

Adds the steerable annotation pipeline (`lerobot-annotate`) that populates
the `language_persistent` and `language_events` columns introduced in
PR 1 directly into `data/chunk-*/file-*.parquet`. No flavor namespace,
no sidecar tree.

Modules produced:
- Module 1 (plan_subtasks_memory): Pi0.7-style subtasks, plan (init +
  refresh on interjection), MEM-style memory at subtask boundaries.
- Module 2 (interjections_and_speech): t=0 speech-only acknowledgement,
  mid-episode paired interjection + speech tool-call atom.
- Module 3 (general_vqa): bbox/keypoint/count/attribute/spatial pairs at
  configurable cadence with one-retry JSON validation.

Writer enforces: per-episode persistent identity, exact-frame event
timestamps, column routing per `column_for_style`, dataset-level `tools`
column with the `say` schema, drops legacy `subtask_index`. Validator
runs against staged JSONL artifacts before the writer rewrites parquet.

Adds `lerobot-annotate` console script, `annotations` extra (datatrove +
optional vllm), `make annotation-e2e` opt-in smoke target, and
`docs/source/annotation_pipeline.mdx`.

Branched from PR 1 (`feat/language-columns`).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/annotations/test_validator.py

@@ -0,0 +1,125 @@
+#!/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.
+"""Validator behavior tests."""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+from lerobot.annotations.steerable_pipeline.reader import iter_episodes
+from lerobot.annotations.steerable_pipeline.staging import EpisodeStaging
+from lerobot.annotations.steerable_pipeline.validator import StagingValidator
+from lerobot.annotations.steerable_pipeline.writer import speech_atom
+
+
+def _validate(root: Path, staging_dir: Path):
+    records = list(iter_episodes(root))
+    return StagingValidator().validate(records, staging_dir)
+
+
+def test_validator_catches_misaligned_timestamps(fixture_dataset_root: Path, tmp_path: Path) -> None:
+    staging_dir = tmp_path / "stage"
+    EpisodeStaging(staging_dir, 0).write(
+        "module_3",
+        [
+            {
+                "role": "assistant",
+                "content": json.dumps({"label": "cup", "count": 2}, sort_keys=True),
+                "style": "vqa",
+                "timestamp": 9.999,  # not on any 10 fps frame
+                "tool_calls": None,
+            }
+        ],
+    )
+    report = _validate(fixture_dataset_root, staging_dir)
+    assert not report.ok
+    assert any("does not match any source frame timestamp" in e for e in report.errors)
+
+
+def test_validator_catches_orphan_speech(fixture_dataset_root: Path, tmp_path: Path) -> None:
+    staging_dir = tmp_path / "stage"
+    EpisodeStaging(staging_dir, 0).write(
+        "module_2",
+        [
+            speech_atom(0.0, "Got it."),
+            # interjection at 0.3s with NO paired speech
+            {
+                "role": "user",
+                "content": "skip it",
+                "style": "interjection",
+                "timestamp": 0.3,
+                "tool_calls": None,
+            },
+        ],
+    )
+    report = _validate(fixture_dataset_root, staging_dir)
+    assert not report.ok
+    assert any("paired speech" in e for e in report.errors)
+
+
+def test_validator_catches_inconsistent_plan_memory(fixture_dataset_root: Path, tmp_path: Path) -> None:
+    staging_dir = tmp_path / "stage"
+    EpisodeStaging(staging_dir, 0).write(
+        "module_1",
+        [
+            {
+                "role": "assistant",
+                "content": "1. do x",
+                "style": "plan",
+                "timestamp": 0.0,
+                "tool_calls": None,
+            },
+            {
+                "role": "assistant",
+                "content": "do x",
+                "style": "subtask",
+                "timestamp": 0.0,
+                "tool_calls": None,
+            },
+        ],
+    )
+    EpisodeStaging(staging_dir, 0).write(
+        "module_2",
+        [
+            speech_atom(0.0, "Got it."),
+            speech_atom(0.4, "Replanning."),
+            {
+                "role": "user",
+                "content": "replan",
+                "style": "interjection",
+                "timestamp": 0.4,
+                "tool_calls": None,
+            },
+        ],
+    )
+    report = _validate(fixture_dataset_root, staging_dir)
+    # missing co-timestamped plan refresh at 0.4s → error
+    assert not report.ok
+    assert any("co-timestamped plan update" in e for e in report.errors)
+
+
+def test_validator_catches_wrong_column(fixture_dataset_root: Path, tmp_path: Path) -> None:
+    staging_dir = tmp_path / "stage"
+    EpisodeStaging(staging_dir, 0).write(
+        "module_1",
+        [
+            {"role": "user", "content": "where?", "style": "vqa", "timestamp": 0.0, "tool_calls": None},
+        ],
+    )
+    report = _validate(fixture_dataset_root, staging_dir)
+    assert not report.ok
+    assert any("module_1 emitted style 'vqa'" in e or "must be persistent" in e for e in report.errors)