fix(hub): pin pretrained artifacts to one commit

tests/configs/test_policy_revision_pinning.py

@@ -0,0 +1,77 @@
+# 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.
+
+import json
+from dataclasses import dataclass
+
+from lerobot.configs import PreTrainedConfig
+
+
+@PreTrainedConfig.register_subclass("revision_pinning_test")
+@dataclass
+class RevisionPinningTestConfig(PreTrainedConfig):
+    @property
+    def observation_delta_indices(self) -> list | None:
+        return None
+
+    @property
+    def action_delta_indices(self) -> list | None:
+        return None
+
+    @property
+    def reward_delta_indices(self) -> list | None:
+        return None
+
+    def get_optimizer_preset(self):
+        raise NotImplementedError
+
+    def get_scheduler_preset(self):
+        raise NotImplementedError
+
+    def validate_features(self) -> None:
+        pass
+
+
+def test_pretrained_config_pins_resolved_hub_commit(monkeypatch, tmp_path):
+    commit_hash = "a" * 40
+    snapshot_dir = tmp_path / "models--user--policy" / "snapshots" / commit_hash
+    RevisionPinningTestConfig(device="cpu").save_pretrained(snapshot_dir)
+    calls = []
+
+    def fake_hub_download(**kwargs):
+        calls.append(kwargs)
+        return str(snapshot_dir / "config.json")
+
+    monkeypatch.setattr("lerobot.configs.policies.hf_hub_download", fake_hub_download)
+
+    config = PreTrainedConfig.from_pretrained("user/policy", revision="main")
+
+    assert calls[0]["revision"] == "main"
+    assert config._commit_hash == commit_hash
+    assert config._commit_hash_source == "user/policy"
+    assert config.get_hub_revision("user/policy", "main") == commit_hash
+    assert config.get_hub_revision("user/base-policy", "base-tag") == "base-tag"
+
+
+def test_runtime_commit_hash_is_not_serialized(tmp_path):
+    config = RevisionPinningTestConfig(device="cpu")
+    config._set_hub_commit_hash("a" * 40, "user/policy")
+
+    config.save_pretrained(tmp_path)
+
+    serialized_config = json.loads((tmp_path / "config.json").read_text())
+    assert "_commit_hash" not in serialized_config
+    assert "_commit_hash_source" not in serialized_config
+    assert "_runtime_commit_hash" not in serialized_config
+    assert "_runtime_commit_hash_source" not in serialized_config