State

@app.tool()
def add_to_cart(product_id: str) -> dict:
    """Add a product to the cart."""
    cart = app.get_state("cart", [])
    cart.append(product_id)
    app.set_state("cart", cart)
    return {"cart": cart}

@app.tool()
def checkout(payment_method: str) -> dict:
    """Complete the purchase using items in the cart."""
    cart = app.get_state("cart", [])
    total = calculate_total(cart)
    return {"order_id": "ORD-123", "items": cart, "total": total}

app = Concierge("my-server")
# State lives in process memory:fast but not persistent across restarts

export CONCIERGE_STATE_URL=postgresql://user:pass@host/db

app = Concierge("my-server")
# Concierge auto-detects the env var and uses Postgres

@app.tool()
def select_flight(flight_id: str) -> dict:
    app.set_state("selected_flight", flight_id)
    return {"selected": flight_id}

@app.tool()
def select_hotel(hotel_id: str) -> dict:
    app.set_state("selected_hotel", hotel_id)
    return {"selected": hotel_id}

@app.tool()
def book_trip(payment: str) -> dict:
    flight = app.get_state("selected_flight")
    hotel = app.get_state("selected_hotel")
    return {"booking": {"flight": flight, "hotel": hotel}}

@app.tool()
def checkout(payment_method: str) -> dict:
    cart = app.get_state("cart", [])
    if not cart:
        return {"error": "Cart is empty. Add items first."}
    return {"order_id": "ORD-123", "items": cart}