Let's fix the SQLDatabaseToolkit import issue

app.py

@@ -8,15 +8,17 @@ import logging
 try:
     # Intentar importar dependencias opcionales
     from langchain_community.agent_toolkits import create_sql_agent
+    from langchain_community.agent_toolkits.sql.toolkit import SQLDatabaseToolkit
     from langchain_community.utilities import SQLDatabase
     from langchain_google_genai import ChatGoogleGenerativeAI
     from langchain.agents.agent_types import AgentType
+    from langchain_core.messages import AIMessage, HumanMessage, SystemMessage
     import pymysql
     from dotenv import load_dotenv
     
     DEPENDENCIES_AVAILABLE = True
-except ImportError:
-    # Si faltan dependencias, la aplicación funcionará en modo demo
+except ImportError as e:
+    logger.warning(f"Some dependencies are not available: {e}")
     DEPENDENCIES_AVAILABLE = False
 
 # Configuración de logging