Update utils/database.py

utils/database.py

@@ -1,6 +1,11 @@
 # utils/database.py
 from langchain.memory import ConversationBufferWindowMemory
-from langchain_core.messages import HumanMessage, AIMessage, SystemMessage
+from langchain_core.messages import (
+    HumanMessage, 
+    AIMessage, 
+    SystemMessage,
+    BaseMessage  # Added this import
+)
 from langchain.chains import ConversationalRetrievalChain
 from langchain.chat_models import ChatOpenAI
 from langchain.agents import AgentExecutor, Tool, create_openai_tools_agent