Fix Gradio JSON schema error by returning JSON as string

ui/detection_wrapper.py

@@ -12,6 +12,7 @@ import os
 import requests
 import base64
 import io
+import json
 from PIL import Image
 from typing import Tuple, Optional
 import traceback
@@ -83,7 +84,8 @@ def detect_with_service(
             detections_list = list(json_payload.get("detections", {}).values())
             summary_text = f"**OCR-only mode**\n**Total OCR texts:** {len(detections_list)}"
             
-            return annotated, summary_text, json_payload
+            # Return JSON as string for Gradio compatibility
+            return annotated, summary_text, json.dumps(json_payload, indent=2)
 
         # Standard detection path
         service = get_detection_service()
@@ -136,7 +138,8 @@ def detect_with_service(
         summary_lines.append(f"- BLIP description: {'✅ Enabled' if enable_blip else '❌ Disabled'}")
         summary_text = "\n".join(summary_lines)
 
-        return annotated, summary_text, json_payload
+        # Return JSON as string for Gradio compatibility
+        return annotated, summary_text, json.dumps(json_payload, indent=2)
         
     except Exception as e:
         error_msg = f"""❌ **Error during detection:**
@@ -286,7 +289,8 @@ The API request timed out after {timeout_seconds} seconds.
             ocr_only=json_payload.get("parameters", {}).get("ocr_only", False)
         )
 
-        return annotated_image, summary_text, json_payload
+        # Return JSON as string for Gradio compatibility
+        return annotated_image, summary_text, json.dumps(json_payload, indent=2) if json_payload else None
         
     except Exception as e:
         error_msg = f"""❌ **Error during detection:**

ui/shared_interface.py

@@ -177,7 +177,8 @@ def create_interface(
                 summary_output = gr.Markdown(label="Detection Summary")
                 
                 with gr.Accordion("Raw Results (JSON)", open=False):
-                    json_output = gr.JSON(label="Detections JSON")
+                    json_output = gr.Code(label="Detections JSON", language="json")
+
 
                 with gr.Accordion("API Quickstart", open=False):
                     api_docs = gr.Markdown(