Add error if with CDC if cache_latents or cache_latents_to_disk is not set

tests/library/test_cdc_cache_detection.py

@@ -243,6 +243,43 @@ def test_cdc_cache_detection_partial_cache():
         assert result is False, "Should detect that some CDC cache files are missing"
 
 
+def test_cdc_requires_latent_caching():
+    """
+    Test that CDC-FM gives a clear error when latent caching is not enabled.
+    """
+
+    with tempfile.TemporaryDirectory() as tmpdir:
+        # Setup mock dataset with NO latent caching (both latents and latents_npz are None)
+        image_info = ImageInfo(
+            image_key="test_image",
+            num_repeats=1,
+            caption="test",
+            is_reg=False,
+            absolute_path=str(Path(tmpdir) / "image.png")
+        )
+        image_info.latents_npz = None  # No disk cache
+        image_info.latents = None  # No memory cache
+        image_info.bucket_reso = (512, 512)
+
+        mock_dataset = MockDataset({"test_image": image_info})
+        dataset_group = DatasetGroup([mock_dataset])
+
+        # Test: Attempt to cache CDC without latent caching enabled
+        with pytest.raises(ValueError) as exc_info:
+            dataset_group.cache_cdc_gamma_b(
+                k_neighbors=256,
+                k_bandwidth=8,
+                d_cdc=8,
+                gamma=1.0
+            )
+
+        # Verify: Error message should mention latent caching requirement
+        error_message = str(exc_info.value)
+        assert "CDC-FM requires latent caching" in error_message
+        assert "cache_latents" in error_message
+        assert "cache_latents_to_disk" in error_message
+
+
 if __name__ == "__main__":
     # Run tests with verbose output
     pytest.main([__file__, "-v"])