fix(lab): stabilize recorded spatial playback

src/k1link/perception/geometry.py

@@ -276,6 +276,13 @@ class RecordedGeometryStore:
         points.setflags(write=False)
         return points
 
+    @property
+    def maximum_current_point_count(self) -> int:
+        """Return the immutable source-pack upper bound for one recorded increment."""
+
+        counts = np.diff(np.asarray(self._source["cloud_offsets"], dtype=np.int64))
+        return int(counts.max(initial=0))
+
     def pose_values_for_frame(
         self,
         frame_id: str,
@@ -946,7 +953,10 @@ def _camera_unavailable_observation(
     )
 
 
-def _load_npz(path: Path, label: str) -> dict[str, npt.NDArray[np.generic]]:
+def _load_npz(
+    path: Path,
+    label: str,
+) -> dict[str, npt.NDArray[np.generic]]:
     try:
         with np.load(path, allow_pickle=False) as archive:
             return {name: np.asarray(archive[name]) for name in archive.files}