from langchain.memory import ConversationEntityMemory
from langchain_openai import ChatOpenAI
llm = ChatOpenAI(model="gpt-4o", temperature=0.4)
from langchain.memory import ConversationBufferMemory

# تأكد إن الـ memory معرفة صح
memory = ConversationBufferMemory(
    memory_key="chat_history",
    return_messages=True,  # مهم جداً!
    output_key="output"
)