Reject unimplemented WorldMem memory backend

datasets/video/memory_selection.py

@@ -400,7 +400,17 @@ def select_memory_indices(poses, target_positions, cfg=None, split: str = "train
     }
     indices, masks = _empty_selection(counts)
 
-    if not bool(cfg_get(cfg, "enabled", True)) or len(target_positions) == 0:
+    enabled = bool(cfg_get(cfg, "enabled", True))
+    backend = cfg_get(cfg, "backend", "dememwm")
+    backend = "dememwm" if backend is None else str(backend).lower()
+    if enabled and backend != "dememwm":
+        if backend == "worldmem":
+            raise NotImplementedError(
+                "memory_selection.backend='worldmem' is not implemented for DeMemWM latent data"
+            )
+        raise ValueError(f"Unsupported memory_selection.backend='{backend}'")
+
+    if not enabled or len(target_positions) == 0:
         return indices, masks
 
     target_start = int(target_positions[0])

tests/test_dememwm_latent_dataset.py

@@ -41,6 +41,13 @@ def _poses(num_frames):
 
 
 class MemorySelectionTests(unittest.TestCase):
+    def test_worldmem_backend_is_explicitly_rejected_until_implemented(self):
+        poses = _poses(8)
+        cfg = _selection_cfg(backend="worldmem")
+
+        with self.assertRaisesRegex(NotImplementedError, "worldmem"):
+            select_memory_indices(poses, np.array([4, 5]), cfg, split="validation")
+
     def test_revisit_uses_sampled_fov_selection(self):
         poses = np.array(
             [