Shopping: Restock within a budget, with your approval

examples/62-shopping-restock.halo policies |! people

Checks prices for what's running low, proposes a cart, and refuses any cart over budget in code (Validate), not just in the prompt. You approve the cart from a link on your phone before anything is ordered. Schedule it with halo.json for a weekly restock.

Open in the playground →

// ============================================================
// Shopping: Restock within a budget, with your approval
// ============================================================
// Checks prices for what's running low, proposes a cart, and refuses
// any cart over budget in code (Validate), not just in the prompt.
// You approve the cart from a link on your phone before anything
// is ordered. Schedule it with halo.json for a weekly restock.
// ============================================================

policy Budget    : MaxSpend(0.20)
policy CartShape : Require(JSON) & Validate("total", "<=", "context.input.budget")

tool Prices : REST("api.example-grocer.com/v1", apiKey: Env.GROCER_KEY)
tool Orders : POST("api.example-grocer.com/v1/orders", apiKey: Env.GROCER_KEY, sendInput: false)

schema Cart {
  items: Array<Object>
  total: Number
  notes: String
}

agent Shopper [anthropic/claude-haiku-4-5, temp: 0.0]
  system """
    You build grocery carts. Prefer the cheapest item that meets the need,
    respect the budget, and say what you skipped and why. Answer with
    JSON: {"items": [{"sku": "...", "name": "...", "qty": 1, "price": 0}], "total": 0, "notes": "..."}
  """
  equips Prices
  requires Budget, CartShape

@correct(2)
@retry(2, 5s)
pipeline RestockPantry(running_low: List, budget: Number) -> Cart:
  running_low
    // 1. Current prices for everything on the list
    |> Prices.search(items: running_low) as prices

    // 2. Propose a cart; a cart over budget is rejected and @correct asks again
    |> Shopper.build_cart("Restock these within a budget of {{budget}}.", context.data.prices) as cart

    // 3. You approve before money is spent
    |! yield(msg: "Order this cart?", [context.data.cart]) as approval
    |? (context.data.approval.approved == true)

    // 4. Place the order
    |> Orders.create(items: context.data.cart.items, total: context.data.cart.total) as order
    |> System.Pick(context.data.cart, fields: ["items", "total", "notes"])