Update app.py

app.py

@@ -241,7 +241,8 @@ class WarehouseStitcher:
         result_pil.save(buf, format='PNG', optimize=True)
         buf.seek(0)
         
-        return result_pil, "\n".join(logs), buf
+        # Return (image preview, logs, downloadable file)
+        return result_pil, "\n".join(logs), ("stitched_result.png", buf.getvalue())
 
 
 class PoseGuidedWarehouseStitcher(WarehouseStitcher):