{
  "handle": "my-shipping-app",
  "name": "Custom Shipping",
  "version": "1.0.0",
  "extensions": {
    "functions": [
      {
        "type": "shipping_rate",
        "handle": "custom-rates",
        "title": "Custom Shipping Rates",
        "entrypoint": "dist/shipping-rate.wasm"
      }
    ]
  }
}

interface ShippingRateInput {
  cart: {
    items: CartItem[];
    totalPrice: number;   // Subtotal in display currency (e.g. 199.99)
    itemCount: number;
    currency: string;     // e.g. "INR", "USD"
  };
  destination: {
    country: string;
    city: string;
    province: string;
    zip: string;
  };
  shippingAddress?: {     // Only present on the order-placement dispatch
    firstName: string;
    lastName: string;
    address1: string;
    address2: string;
    city: string;
    province: string;
    country: string;
    zip: string;
    phone: string;
  };
  currency: string;
}

interface CartItem {
  id: string;             // lineItemId
  variantId: string;
  productId: string;
  title: string;
  quantity: number;
  price: number;          // Effective unit price (display currency)
  originalPrice: number;  // Compare-at unit price
}

interface ShippingRateOutput {
  rates: ShippingRate[];
}

interface ShippingRate {
  name: string;            // Required — shown as the radio label
  price: number;           // Required — in display currency. 0 = free
  description?: string;    // Sub-line under the name
  minDeliveryDays?: number; // Optional — estimated delivery window (min)
  maxDeliveryDays?: number; // Optional — estimated delivery window (max)

  // Optional — what kind of fulfillment this rate represents. Defaults
  // to "standard". Local pickup and pickup point rates render with an
  // extra indicator strip under the radio label.
  kind?: 'standard' | 'local_pickup' | 'pickup_point';
  pickup?: {
    location_id?: string;  // For local_pickup — your warehouse / store
    provider?: string;     // For pickup_point — e.g. "DHL", "UPS Access Point"
    address?: {
      address1?: string;
      city?: string;
      province?: string;
      country?: string;
      zip?: string;
    };
    window?: string;       // Free-text, e.g. "Mon–Fri 10am–6pm"
  };
}

rates.push({
  name: 'Pick up at our flagship',
  price: 0,
  kind: 'local_pickup',
  pickup: {
    location_id: 'gid://launchmystore/Location/flagship-mumbai',
    address: { address1: '101 Linking Rd', city: 'Mumbai', country: 'IN', zip: '400050' },
    window: 'Mon–Sat 10am–8pm',
  },
});

{
  ...yourRate,
  appId: '<app-handle>',
  source: 'app_function',
}

function calculateShippingRates(input, config) {
  const rates = [];
  const threshold = config.freeShippingThreshold || 50;

  if (input.cart.totalPrice >= threshold) {
    rates.push({
      name: 'Free Shipping',
      price: 0,
      description: '5–7 business days'
    });
  } else {
    rates.push({
      name: 'Standard Shipping',
      price: 5.99,
      description: '5–7 business days'
    });
  }

  return { rates };
}

function calculateShippingRates(input) {
  const country = input.destination.country;
  const zones = {
    domestic:     { match: ['IN'],                 std: 5.99,  fast: 12.99 },
    neighbour:    { match: ['NP', 'BD', 'LK'],     std: 9.99,  fast: 19.99 },
    intl:         { match: null,                   std: 24.99,             }
  };

  const zone =
    Object.values(zones).find(z => z.match?.includes(country)) || zones.intl;

  const rates = [{ name: 'Standard', price: zone.std, description: '5–10 days' }];
  if (zone.fast) rates.push({ name: 'Express', price: zone.fast, description: '2–3 days' });
  return { rates };
}

async function fetchCarrierRates(input, config) {
  const res = await fetch(config.apiEndpoint, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json', Authorization: `Bearer ${config.apiKey}` },
    body: JSON.stringify({
      destination: input.destination,
      packages: input.cart.items.map(i => ({
        quantity: i.quantity,
        price: i.price * i.quantity
      })),
      currency: input.cart.currency
    })
  });
  const carrier = await res.json();

  return {
    rates: carrier.map(r => ({
      name: r.serviceName,
      price: r.totalPrice,        // already in display currency from your API
      description: r.estimate
    }))
  };
}

Shipping Method
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

○ Standard Shipping — ₹49.00          ← Merchant zone
○ Express Shipping  — ₹149.00         ← Merchant zone

  Powered by Custom Shipping
○ Same-Day Delivery — ₹299.00         ← Your function
○ Pickup at Store   — FREE            ← Your function