Add end chat detection functionality in AI chat

- Introduced a new asynchronous function `detect_end_chat` to identify user intent to end the chat session based on specific phrases.
- Integrated this function into the chat state graph, allowing for a graceful termination of the session with a user-friendly response.
- This enhancement aims to improve user experience by providing clear communication when the chat session is concluded.

ai_chat.py

@@ -369,16 +369,31 @@ async def extract_and_search_properties(state):
     await end_session(state["session_id"])
     return state
 
+async def detect_end_chat(state):
+    """
+    Detect if the user wants to end the chat session.
+    """
+    user_message = state["user_message"].lower()
+    session_id = state["session_id"]
+    
+    if any(phrase in user_message for phrase in ["thank you", "thanks", "bye", "goodbye", "end chat"]):
+        await end_session(session_id)
+        return {"response": "Thanks for chatting! I've ended this session. Goodbye!"}
+    
+    return {"response": None}
+
 # --- Build LangGraph ---
 graph = StateGraph(ChatState)
 graph.add_node("persona_update", RunnableLambda(extract_and_update_persona))
 graph.add_node("intent_update", RunnableLambda(extract_and_update_intent))
 graph.add_node("property_search", RunnableLambda(extract_and_search_properties))
+graph.add_node("exit_check", RunnableLambda(detect_end_chat))
 graph.add_node("chat", RunnableLambda(chat_with_session_memory))
 graph.set_entry_point("persona_update")
 graph.add_edge("persona_update", "intent_update")
 graph.add_edge("intent_update", "property_search")
-graph.add_edge("property_search", "chat")
+graph.add_edge("property_search", "exit_check")
+graph.add_edge("exit_check", "chat")
 graph.add_edge("chat", END)
 chat_graph = graph.compile()