fix pi052 runtime and training safety

tests/policies/pi052/test_pi052_bucketed_ce.py

@@ -19,7 +19,71 @@ import torch
 
 pytest.importorskip("transformers")
 
-from lerobot.policies.pi052.modeling_pi052 import _lin_ce_flat
+from lerobot.policies.pi052.modeling_pi052 import _lin_ce_flat, _shifted_lin_ce
+
+
+def test_shifted_ce_none_retains_distinct_per_sample_losses():
+    hidden = torch.tensor(
+        [
+            [[8.0, 0.0], [0.0, 8.0], [0.0, 0.0]],
+            [[0.0, 8.0], [8.0, 0.0], [0.0, 0.0]],
+        ]
+    )
+    labels = torch.tensor([[0, 0, 1], [0, 0, 1]])
+    losses = _shifted_lin_ce(hidden, torch.eye(2), labels, reduction="none")
+
+    assert losses.shape == (2,)
+    assert losses[0] < losses[1]
+
+
+def test_checkpoint_resolution_forwards_explicit_hub_options(monkeypatch, tmp_path):
+    import lerobot.policies.pi052.modeling_pi052 as modeling_pi052
+
+    checkpoint = tmp_path / "model.safetensors"
+    checkpoint.touch()
+    calls = []
+
+    def fake_cached_file(model_id, filename, **kwargs):
+        calls.append((model_id, filename, kwargs))
+        return None if filename.endswith("index.json") else str(checkpoint)
+
+    monkeypatch.setattr(modeling_pi052, "cached_file", fake_cached_file)
+    files = modeling_pi052._resolve_weight_files(
+        "org/model",
+        force_download=True,
+        resume_download=True,
+        proxies={"https": "proxy"},
+        token="secret",
+        cache_dir=tmp_path / "cache",
+        local_files_only=True,
+        revision="commit",
+    )
+
+    assert files == [checkpoint]
+    for _model_id, _filename, kwargs in calls:
+        assert kwargs["revision"] == "commit"
+        assert kwargs["cache_dir"] == tmp_path / "cache"
+        assert kwargs["force_download"] is True
+        assert kwargs["resume_download"] is True
+        assert kwargs["proxies"] == {"https": "proxy"}
+        assert kwargs["token"] == "secret"
+        assert kwargs["local_files_only"] is True
+
+
+def test_checkpoint_resolution_rejects_local_directory_without_weights(tmp_path):
+    import lerobot.policies.pi052.modeling_pi052 as modeling_pi052
+
+    with pytest.raises(FileNotFoundError, match="model.safetensors"):
+        modeling_pi052._resolve_weight_files(
+            tmp_path,
+            force_download=False,
+            resume_download=None,
+            proxies=None,
+            token=None,
+            cache_dir=None,
+            local_files_only=False,
+            revision=None,
+        )
 
 
 @pytest.mark.parametrize("z_loss_weight", [0.0, 1e-4])