feat(dataset): integrate episode streaming into training

tests/test_streaming_core_imports.py

@@ -0,0 +1,39 @@
+#!/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
+
+from __future__ import annotations
+
+import subprocess
+import sys
+
+
+def test_streaming_core_imports_without_dataset_extra() -> None:
+    code = """
+import importlib.abc
+import sys
+
+class BlockDatasets(importlib.abc.MetaPathFinder):
+    def find_spec(self, fullname, path, target=None):
+        if fullname == "datasets" or fullname.startswith("datasets."):
+            raise ModuleNotFoundError("blocked optional datasets dependency")
+        return None
+
+sys.meta_path.insert(0, BlockDatasets())
+from lerobot.streaming.episode_video import EpisodeByteCache, ExactCoveragePool
+from lerobot.streaming.mp4 import Mp4Index
+"""
+    result = subprocess.run(
+        [sys.executable, "-c", code],
+        capture_output=True,
+        text=True,
+        timeout=30,
+    )
+
+    assert result.returncode == 0, result.stderr