Deploying a Persistent Agent

What a real deployment actually needs

Lesson 14 gave a graph memory that survives a restart, per thread. Lesson 25 gave a graph memory that crosses threads, per user. Neither one replaces the other, they solve different problems: "what did we discuss in this conversation" versus "what do I know about this person, regardless of which conversation they're in." A real deployed agent typically needs both running at the same time, on the same compiled graph.

Attaching both to one compile call

return builder.compile(checkpointer=checkpointer, store=store)

compile() accepts both a checkpointer and a store as independent keyword arguments. Neither one knows the other exists, they're separate systems, doing separate jobs, that both happen to be available to every node in this graph.

The checkpointer half: durable, per-thread

with SqliteSaver.from_conn_string(str(DB_PATH)) as checkpointer:
    app = build_app_for_user(user_id, checkpointer)
    ...

Exactly Lesson 14's pattern: a real .sqlite file on disk, opened as a context manager. Every turn within one thread_id is remembered here, and survives the program exiting and restarting, same as before.

The store half: cross-thread, keyed by user

store = InMemoryStore()

def chatbot(state: MessagesState) -> dict:
    saved = store.search(("profile", user_id))
    ...

Exactly Lesson 25's pattern: one store shared across every thread, looked up by user_id rather than thread_id. Note this store is InMemoryStore, still RAM-only in this lesson, a real deployment would typically back the store with its own persistent storage too, the point here is the two memory systems coexisting, not that both happen to be durable in this specific demo.

Proving both work together

config_1 = {"configurable": {"thread_id": "support-session-1"}}
r2 = app.invoke({"messages": [HumanMessage("What did I just tell you?")]}, config_1)
# answered via the CHECKPOINTER, same thread as the previous turn

config_2 = {"configurable": {"thread_id": "support-session-2"}}
r3 = app.invoke({"messages": [HumanMessage("What account tier am I on?")]}, config_2)
# answered via the STORE, a brand new thread, same user

config_1's second turn works because the checkpointer remembers turn one, same thread. config_2 is an entirely new thread with no checkpointer history in common with config_1 at all, yet it still knows the account tier, because that fact came from the store, looked up by user_id, completely independent of which thread asked.