Fix upload endpoint: accept JSON payload, add logging

Take token + paths as JSON string instead of gr.File.
Add print logging for upload flow debugging.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app.py

@@ -241,22 +241,30 @@ def build_app() -> gr.Blocks:
         ask_btn = gr.Button(visible=False)
         ask_btn.click(api_ask_stream, inputs=ask_inputs, outputs=ask_output, api_name="ask")
 
-        # Upload endpoint — accepts files, creates workspace
-        upload_token = gr.Textbox(visible=False)
-        upload_files = gr.File(visible=False, file_count="multiple")
+        # Upload endpoint — accepts token + JSON list of file paths from /gradio_api/upload
+        upload_input = gr.Textbox(visible=False)
         upload_output = gr.Textbox(visible=False)
 
-        def api_upload(token, files):
+        def api_upload(payload):
+            print(f"[upload] raw payload: {payload!r}")
+            try:
+                data = json.loads(payload)
+                token = data.get("token", "")
+                file_paths = data.get("paths", [])
+            except (json.JSONDecodeError, AttributeError) as exc:
+                print(f"[upload] parse error: {exc}")
+                return json.dumps({"error": "Invalid payload."})
+            print(f"[upload] token={'***' if token else 'empty'}, paths={file_paths}")
             if ACCESS_TOKEN and token != ACCESS_TOKEN:
                 return json.dumps({"error": "Invalid access token."})
-            if not files:
+            if not file_paths:
                 return json.dumps({"error": "No files provided."})
-            file_paths = [f.name if hasattr(f, "name") else str(f) for f in files]
             workspace = save_uploaded_files(file_paths)
+            print(f"[upload] workspace created: {workspace}")
             return json.dumps({"workspace_path": str(workspace), "file_count": len(file_paths)})
 
         upload_btn = gr.Button(visible=False)
-        upload_btn.click(api_upload, inputs=[upload_token, upload_files], outputs=upload_output, api_name="upload")
+        upload_btn.click(api_upload, inputs=upload_input, outputs=upload_output, api_name="upload")
 
         # Document viewer endpoint
         doc_input = gr.Textbox(visible=False)