How to Add Memory to an AI Agent

1"""Personal finance coach with two memory layers: a checkpointer for
2within-session recall and Mem0 for facts that persist across sessions.
3Run: python finance_coach_memory.py
4(pip install langchain langgraph mem0ai; set ANTHROPIC_API_KEY and OPENAI_API_KEY)
5"""
6import uuid
7
8from langchain.agents import create_agent
9from langgraph.checkpoint.memory import InMemorySaver
10from mem0 import Memory
11
12long_term_memory = Memory()
13
14
15def save_long_term_facts(user_id: str, messages: list[dict]) -> None:
16    long_term_memory.add(messages, user_id=user_id)
17
18
19def build_system_prompt(user_id: str, current_message: str, max_facts: int = 5) -> str:
20    hits = long_term_memory.search(current_message, filters={"user_id": user_id})
21    results = sorted(
22        hits.get("results", []), key=lambda m: m.get("score", 0), reverse=True
23    )[:max_facts]
24    facts = "\n".join(f"- {m['memory']}" for m in results)
25    base = "You are a personal finance coach. Be specific with numbers."
26    return f"{base}\n\nKnown facts about this user:\n{facts}" if facts else base
27
28
29def run_turn(user_id: str, thread_id: str, user_message: str) -> str:
30    agent = create_agent(
31        model="anthropic:claude-sonnet-5-5",
32        tools=[],
33        system_prompt=build_system_prompt(user_id, user_message),
34        checkpointer=InMemorySaver(),
35    )
36    config = {"configurable": {"thread_id": thread_id}}
37    result = agent.invoke({"messages": [{"role": "user", "content": user_message}]}, config=config)
38    return result["messages"][-1].content
39
40
41if __name__ == "__main__":
42    user_id = "alex"
43
44    # Session 1: establish a goal, then ask a follow-up in the same thread
45    thread_1 = str(uuid.uuid4())
46    run_turn(user_id, thread_1, "I'm trying to save $20k for a down payment")
47    print(run_turn(user_id, thread_1, "How much should I save monthly for that in 2 years?"))
48
49    # Persist what was learned for future sessions
50    save_long_term_facts(
51        user_id,
52        [
53            {"role": "user", "content": "I'm trying to save $20k for a down payment"},
54            {"role": "assistant", "content": "Got it, saving for a $20k down payment."},
55        ],
56    )
57
58    # Session 2: a brand new thread, days later, still knows the goal
59    thread_2 = str(uuid.uuid4())
60    print(run_turn(user_id, thread_2, "How's my savings plan looking?"))
61