Fix: Correct type annotation causing Gradio schema serialization bug

app.py

@@ -80,11 +80,14 @@ if __name__ == "__main__":
     
     if os.environ.get("SPACE_ID"):
         # Running in HF Spaces - use settings for public hosting
+        # show_api=False disables the /api endpoint which has a bug in Gradio 5.9.1
+        # that crashes on complex type schemas (TypeError: 'bool' is not iterable)
         logger.info("Starting seg_app on Hugging Face Spaces...")
         demo.launch(
             server_name="0.0.0.0",
             server_port=7860,
             share=False,
+            show_api=False,
         )
     else:
         # Local development
@@ -93,4 +96,5 @@ if __name__ == "__main__":
             server_name="127.0.0.1",
             server_port=7869,
             share=False,
+            show_api=False,
         )

seg_app/ui/gradio_app.py

@@ -170,14 +170,14 @@ def update_coronal_slice(index: int) -> Optional[Image.Image]:
 
 def run_segmentation_task(
     model_id: str,
-) -> Tuple[Image.Image, Image.Image, Image.Image, Dict[str, Any]]:
+) -> Tuple[Optional[Image.Image], Optional[Image.Image], Optional[Image.Image], str]:
     """Run segmentation on the current volume and display results.
     
     Args:
         model_id: ID of the model to use for segmentation
         
     Returns:
-        Tuple of (axial_overlay, sagittal_overlay, coronal_overlay, metrics)
+        Tuple of (axial_overlay, sagittal_overlay, coronal_overlay, metrics_str)
     """
     global _current_mask