using RunnableWithMessageHistory by passing the correct runnable argument

workflow.py

@@ -25,7 +25,7 @@ def get_workflow():
 
     # Use RunnableWithMessageHistory for session memory
     conversation_chain = RunnableWithMessageHistory(
-        llm=chat_model,
+        runnable=chat_model,
         get_session_history=lambda: get_session_history(memory),
         memory=memory,
         verbose=True,