added introductory prompt

backend.py

@@ -131,27 +131,29 @@ def handle_query(query_str: str,
         )
         
         #chat_engine.reset()
-        
         outputs = []
         response = chat_engine.stream_chat(query_str, conversation)
-        
+        sources = []  # Use a list to collect multiple sources if present
         #response = chat_engine.chat(query_str)
+
         for token in response.response_gen:
-          if not token.startswith("system:") and not token.startswith("user:"):
-            
-            if token.startswith("file_path:"):
-              source = token
-          
-            outputs.append(token)
-            print(f"Generated token: {token}")
-            yield "".join(outputs)
-        
-        outputs.append(f"Fonti utilizzate: {source}")
-        yield "".join(outputs)     
-            
-        
-          
-        
+            if not token.startswith("system:") and not token.startswith("user:"):
+                if token.startswith("file_path:"):
+                    sources.append(token)
+                
+                outputs.append(token)
+                print(f"Generated token: {token}")
+                yield "".join(outputs)
+
+        if sources:
+            sources_str = ", ".join(sources)
+            outputs.append(f"Fonti utilizzate: {sources_str}")
+        else:
+            outputs.append("Nessuna fonte specifica utilizzata.")
+
+        yield "".join(outputs)
+
+
     except Exception as e:
         yield f"Error processing query: {str(e)}"