added introductory prompt

backend.py

@@ -102,8 +102,11 @@ def handle_query(query_str: str,
             
             index = build_index("data/chiarimento.txt")
             gr.Info("index costruito con richiesta di chiarimento")
+            chat_engine.reset()
                   
     else:
+      
+        
         # The index is already built, no need to rebuild it.
         storage_context = StorageContext.from_defaults(persist_dir=PERSIST_DIR)
         index = load_index_from_storage(storage_context)