Task/fix tracklet generation bug

src/mouse_tracking/matching/vectorized_features.py

@@ -35,6 +35,10 @@ def __init__(self, detections: list[Detection]):
 
     def _extract_poses(self, detections: list[Detection]) -> np.ndarray:
         """Extract pose data into a vectorized array."""
+        if len(detections) == 0:
+            # Return properly shaped empty array
+            return np.zeros((0, 12, 2), dtype=np.float64)
+
         poses = []
         for det in detections:
             if det.pose is not None:

tests/matching/vectorized_features/test_compute_vectorized_detection_features.py

@@ -33,11 +33,9 @@ def test_init_empty_detections(self):
 
         assert features.n_detections == 0
         assert features.detections == []
-        assert features.poses.shape == (0,)  # Empty array has shape (0,)
+        assert features.poses.shape == (0, 12, 2)  # Properly shaped empty array
         assert features.embeddings.shape == (0, 0)  # Empty embeddings
-        assert (
-            features.valid_pose_masks.shape == ()
-        )  # Empty array results in scalar shape
+        assert features.valid_pose_masks.shape == (0, 12)  # Properly shaped empty mask
         assert features.valid_embed_masks.shape == (0,)
 
     def test_init_mixed_valid_invalid(self, detection_factory):

tests/matching/vectorized_features/test_compute_vectorized_pose_distances.py

@@ -174,15 +174,25 @@ def test_pose_distances_different_sizes(self, features_factory):
         assert distances.shape == (3, 2)
         assert not np.any(np.isnan(distances))  # All should be valid
 
-    def test_pose_distances_empty_features(self):
+    @pytest.mark.parametrize("n_features1, n_features2", [(0, 0), (0, 1), (1, 0)])
+    def test_pose_distances_empty_features(
+        self, n_features1, n_features2, features_factory
+    ):
         """Test pose distance computation with empty features."""
-        features1 = VectorizedDetectionFeatures([])
-        features2 = VectorizedDetectionFeatures([])
+        example_pose_config = [{"has_pose": True, "center": (0, 0)}]
+        features1 = features_factory(
+            n_detections=n_features1, pose_configs=example_pose_config
+        )
+        features2 = features_factory(
+            n_detections=n_features2, pose_configs=example_pose_config
+        )
 
-        # This will likely crash due to empty array indexing - mark as expected behavior
-        # TODO: This reveals a bug in the function with empty features
-        with pytest.raises(IndexError):
-            compute_vectorized_pose_distances(features1, features2)
+        # Should handle empty features gracefully
+        distances = compute_vectorized_pose_distances(features1, features2)
+
+        # Should return empty distance matrix with correct shape
+        assert distances.shape == (n_features1, n_features2)
+        assert distances.dtype == np.float64
 
     def test_pose_distances_single_detection(self, features_factory):
         """Test pose distance computation with single detection."""

tests/matching/vectorized_features/test_get_rotated_poses.py

@@ -115,8 +115,8 @@ def test_get_rotated_poses_empty_detections(self):
             # Should not call rotate_pose
             assert mock_rotate.call_count == 0
 
-            # Should return empty array matching poses shape
-            assert rotated_poses.shape == (0,)
+            # Should return properly shaped empty array
+            assert rotated_poses.shape == (0, 12, 2)
             assert np.array_equal(rotated_poses, features.poses)
 
     def test_get_rotated_poses_uses_detection_rotate_pose(self, detection_factory):