Use a ModelIdentifierField to identify the spandrel model in the UpscaleSpandrelInvocation.

invokeai/backend/spandrel_image_to_image_model.py

@@ -16,6 +16,10 @@ class SpandrelImageToImageModel(RawModel):
     def __init__(self, spandrel_model: ImageModelDescriptor[Any]):
         self._spandrel_model = spandrel_model
 
+    def run(self, image_tensor: torch.Tensor) -> torch.Tensor:
+        """Run the image-to-image model."""
+        return self._spandrel_model(image_tensor)
+
     @classmethod
     def load_from_file(cls, file_path: str | Path):
         model = ModelLoader().load_from_file(file_path)
@@ -67,3 +71,13 @@ class SpandrelImageToImageModel(RawModel):
         # TODO(ryand): spandrel.ImageModelDescriptor.to(...) does not support non_blocking. We will access the model
         # directly if we want to apply this optimization.
         self._spandrel_model.to(device=device, dtype=dtype)
+
+    @property
+    def device(self) -> torch.device:
+        """The device of the underlying model."""
+        return self._spandrel_model.device
+
+    @property
+    def dtype(self) -> torch.dtype:
+        """The dtype of the underlying model."""
+        return self._spandrel_model.dtype