const reply = await dispatchAndWait('BRIDGE_PING');
// → { ok: true, host: 'checkout' }

await dispatchAndWait('TOAST_SHOW', {
  message: 'Gift wrap added',
  variant: 'success',  // or 'error'
});

const cart = await dispatchAndWait('CART_GET');
// {
//   cartId:   'c1-a1b2c3d4-...',     // value of the `cart` cookie
//   items:    [{ id, productId, variantId, title, quantity, price }],
//   itemCount: 3,
//   currency: 'INR',
//   note:     '',
// }

const totals = await dispatchAndWait('CHECKOUT_TOTALS_GET');
// {
//   subtotal:          9600.00,
//   bundleDiscount:    23800.00,   // from cart_transform functions
//   appDiscount:          63.60,   // from discount functions (line/order)
//   shippingDiscount:     50.00,   // from discount functions (shipping)
//   couponDiscount:      225.00,   // from merchant coupon
//   shipping:            100.00,
//   tax:                  18.00,
//   finalPrice:        10273.52,
//   currency: 'INR',
// }

const { email } = await dispatchAndWait('CUSTOMER_GET');
// { email: 'alex@example.com' }

const { currency } = await dispatchAndWait('CURRENCY_GET');
// { currency: 'INR' }

const cost = await dispatchAndWait('COST_GET');
// {
//   subtotalAmount:       { amount: 9600.00,  currencyCode: 'INR' },
//   totalDiscountAmount:  { amount:  288.60,  currencyCode: 'INR' },  // cart_transform + appDiscount + couponDiscount
//   totalShippingAmount:  { amount:  100.00,  currencyCode: 'INR' },
//   totalTaxAmount:       { amount:   18.00,  currencyCode: 'INR' },
//   totalAmount:          { amount: 9429.40,  currencyCode: 'INR' },
// }

const identity = await dispatchAndWait('BUYER_IDENTITY_GET');
// {
//   email:    'alex@example.com',     // '' if the field is empty
//   phone:    '+91-9876543210',       // from selected/manual address
//   customer: { id: 'cus-uuid' }      // null when not logged in
// }

const loc = await dispatchAndWait('LOCALIZATION_GET');
// {
//   country:  { isoCode: 'IN',  name: 'IN' },
//   language: { isoCode: 'en' },
//   currency: { isoCode: 'INR', name: 'INR' },
// }

const { address } = await dispatchAndWait('SHIPPING_ADDRESS_GET');
// address = {
//   firstName:    'Alex',
//   lastName:     'Patel',
//   address1:     '12 MG Road',
//   address2:     'Apt 4B',
//   city:         'Mumbai',
//   provinceCode: 'MH',
//   province:     'MH',
//   countryCode:  'IN',
//   country:      'IN',
//   zip:          '400001',
//   phone:        '+91-9876543210',
//   company:      '',
// } | null

const { address } = await dispatchAndWait('BILLING_ADDRESS_GET');

const { discountCodes } = await dispatchAndWait('DISCOUNT_CODES_GET');
// discountCodes = [{ code: 'WELCOME10', applicable: true }]   // [] when no code is applied

const { appliedGiftCards } = await dispatchAndWait('APPLIED_GIFT_CARDS_GET');
// appliedGiftCards = []

const { deliveryGroups } = await dispatchAndWait('DELIVERY_GROUPS_GET');
// deliveryGroups = [
//   {
//     id: 'default',
//     groupType: 'oneTimePurchase',
//     deliveryOptions: [
//       {
//         id: 'shipping-zone-uuid',
//         title: 'Standard Shipping',
//         cost: { amount: 100.00, currencyCode: 'INR' },
//         description: 'Delivery in 3-5 business days',
//       },
//       // ...
//     ],
//     selectedDeliveryOptionId: null,    // host doesn't track per-group selection today
//   },
// ]

const shop = await dispatchAndWait('SHOP_GET');
// {
//   id:            'store-uuid',
//   name:          'Acme Store',
//   storeDomain:   'acme.launchmystore.io',     // canonical store domain
//   storefrontUrl: 'https://acme.launchmystore.io',
// }

const ins = await dispatchAndWait('INSTRUCTIONS_GET');
// {
//   attributes: { canUpdateAttributes: true },
//   delivery:   { canSelectCustomAddress: true },
//   discounts:  { canUpdateDiscountCodes: true, canRemoveDiscountCodes: false },
//   notes:      { canUpdateNote: true },
//   cartLines:  { canUpdateLines: true, canAddLines: true, canRemoveLines: true },
//   giftCards:  { canUpdate: false },
//   metafields: { canUpdate: false },
// }

const { attributes } = await dispatchAndWait('ATTRIBUTES_GET');
// attributes = { gift_wrap: 'true', delivery_window: 'evening' }

await dispatchAndWait('ORDER_NOTE_SET', {
  note: 'Leave with the concierge, please do not ring the bell.',
});
// { ok: true, note: 'Leave with the concierge, ...' }

await dispatchAndWait('COUPON_APPLY_REQUEST', { code: 'WELCOME10' });
// { ok: true, code: 'WELCOME10' }

import { Cart } from '@launchmystore/app-bridge';
const cart = Cart.create(app);

// Add a new line
await cart.applyCartLinesChange({
  type: 'addCartLine',
  merchandiseId: 'gid://launchmystore/Variant/abc-123',
  quantity: 1,
  attributes: [{ key: 'gift_wrap', value: 'true' }],
});

// Update a line's quantity
await cart.applyCartLinesChange({
  type: 'updateCartLine',
  id: 'gid://launchmystore/CartLine/line-uuid',
  quantity: 3,
});

// Remove a line
await cart.applyCartLinesChange({
  type: 'removeCartLine',
  id: 'gid://launchmystore/CartLine/line-uuid',
});

// Batch
await cart.applyCartLinesChange([
  { type: 'addCartLine', merchandiseId: 'gid://...', quantity: 1 },
  { type: 'removeCartLine', id: 'gid://...' },
]);

{
  ok: true,
  results: Array<{ type: string, ok: boolean, error?: string }>,
}

await cart.applyDiscountCodeChange({
  type: 'addDiscountCode',
  code: 'WELCOME10',
});

await cart.applyNoteChange({
  type: 'updateNote',
  note: 'Leave with concierge — apt 4B',
});

await cart.applyNoteChange({ type: 'removeNote' });

await cart.applyAttributeChange({
  type: 'updateAttribute',
  key: 'gift_wrap',
  value: 'true',
});

await cart.applyAttributeChange({
  type: 'removeAttribute',
  key: 'gift_wrap',
});

const res = await cart.applyGiftCardChange({
  type: 'addGiftCard',
  code: 'GC-12345',
});
// → { ok: false, applicable: false }

await cart.applyShippingAddressChange({
  type: 'updateShippingAddress',
  address: {
    firstName: 'Alex',
    lastName:  'Patel',
    address1:  '12 MG Road',
    city:      'Mumbai',
    provinceCode: 'MH',
    countryCode:  'IN',
    zip:       '400001',
    phone:     '+91-9876543210',
  },
});
// → { ok: true, address: { ...normalised standard shape... } }

{ payload: {}, error: 'cart metafields not supported yet' }

import { BuyerJourney } from '@launchmystore/app-bridge';

const journey = BuyerJourney.create(app);

const unsubscribe = journey.intercept(() => {
  if (!termsAcceptedCheckbox.checked) {
    return {
      behavior: 'block',
      reason: 'You must accept the terms before continuing.',
    };
  }
  return { behavior: 'allow' };
});

// Stop intercepting
unsubscribe();
// or
journey.destroy();

function resize() {
  window.parent.postMessage(
    { type: 'APP_BRIDGE_RESIZE', height: document.documentElement.scrollHeight },
    '*'
  );
}
new ResizeObserver(resize).observe(document.body);

<!doctype html>
<html><body>
  <textarea id="note" placeholder="Leave a note for the courier"></textarea>
  <button id="save">Save instructions</button>
  <div id="status"></div>

  <script>
    let nextId = 0;
    const pending = new Map();
    window.addEventListener('message', (ev) => {
      const d = ev.data;
      if (d?.type !== 'APP_BRIDGE_RESPONSE') return;
      const cb = pending.get(d.id);
      if (cb) { pending.delete(d.id); cb(d.payload, d.error); }
    });
    function dispatchAndWait(action, payload) {
      return new Promise((resolve, reject) => {
        const id = `dn_${++nextId}_${Date.now()}`;
        const to = setTimeout(() => reject(new Error('timeout')), 3000);
        pending.set(id, (p, err) => { clearTimeout(to); err ? reject(new Error(err)) : resolve(p); });
        parent.postMessage({ type: 'APP_BRIDGE_ACTION', action, payload, id }, '*');
      });
    }

    document.getElementById('save').addEventListener('click', async () => {
      const note = document.getElementById('note').value.trim();
      await dispatchAndWait('ORDER_NOTE_SET', { note });
      await dispatchAndWait('TOAST_SHOW', { message: 'Instructions saved', variant: 'success' });
      document.getElementById('status').textContent = 'Saved.';
    });

    new ResizeObserver(() => parent.postMessage(
      { type: 'APP_BRIDGE_RESIZE', height: document.documentElement.scrollHeight },
      '*'
    )).observe(document.body);
  </script>
</body></html>

{
  "extensions": {
    "checkoutExtensions": [
      {
        "target": "checkout-contact-after",
        "appId": "delivery-instructions-1",
        "appName": "Delivery Instructions",
        "handle": "delivery-instructions",
        "iframeUrl": "/extensions/{your-app}/delivery-instructions.html"
      }
    ]
  }
}