CompositeBackend: long-term memory in /memories/

CompositeBackend(
    default=StateBackend(),                                   # any path not listed below
    routes={"/memories/": StoreBackend(namespace=...)},        # this prefix goes to the store
)

from langchain.tools import tool

CATALOG = {
    "paris": {
        "flight": ["Return flight Delhi to Paris: 42,000 rupees"],
        "hotel": ["Seine Budget Inn, Latin Quarter: 5,200 rupees a night",
                  "Hotel Lumiere, Montmartre: 7,500 rupees a night",
                  "Le Grand Opera Hotel: 16,000 rupees a night"],
        "sight": ["Eiffel Tower summit: 3,100 rupees", "Louvre Museum: 2,000 rupees",
                  "Seine river cruise: 1,500 rupees", "Versailles day trip: 2,600 rupees",
                  "Montmartre walking tour: free"],
        "food": ["Cafe breakfast and bistro dinner: 3,000 rupees a day"],
    },
}


@tool
def search_travel(city: str, kind: str) -> str:
    """Search the travel catalog. kind is "flight", "hotel", "sight" or "food". Prices are in rupees."""
    entries = CATALOG.get(city.lower(), {}).get(kind)
    return "\n".join(entries) if entries else f"The catalog has no {kind} entries for {city}."

from deepagents import create_deep_agent
from langchain.chat_models import init_chat_model

model = init_chat_model("groq:openai/gpt-oss-120b", temperature=0, max_retries=6)

from deepagents.backends import CompositeBackend, StateBackend, StoreBackend
from langgraph.checkpoint.memory import InMemorySaver
from langgraph.store.memory import InMemoryStore

def make_agent():
    return create_deep_agent(
        model=model,
        tools=[search_travel],
        backend=CompositeBackend(
            default=StateBackend(),                                    # any other path: this thread only
            routes={"/memories/": StoreBackend(namespace=lambda rt: ("traveller",))},   # kept for every thread
        ),
        store=InMemoryStore(),
        checkpointer=InMemorySaver(),
        system_prompt="You are a travel planner. When the traveller states a preference, save it to /memories/preferences.md. "
                      "Before suggesting anything, read /memories/preferences.md if it exists. "
                      "Use only prices from search_travel. Reply in two short sentences.",
    )

def ask(text, thread_id):
    result = agent.invoke({"messages": [{"role": "user", "content": text}]}, config={"configurable": {"thread_id": thread_id}})
    print(f"[{thread_id}] you:  ", text)
    files_read = [c["args"].get("file_path") for m in result["messages"] for c in getattr(m, "tool_calls", []) if c["name"] == "read_file"]
    print(f"[{thread_id}] read: ", files_read)
    print(f"[{thread_id}] agent:", result["messages"][-1].text)