chat_router.pyfrom domain.ai.service import chatclass Message(BaseModel): role: Union[str, None] = None content : str session_id : str@router.post("lang-chain")def chat_request_by_lang_chain(message: Message): return chat.chat_completion_by_lang_chain(session_id = message.session_id, message=message.content) chat.pyfrom langchain_core.prompts import ChatPromptTemplate, MessagesPlaceh..