International shipping rates are configured (if applicable)

An address form that accepts 12 countries but routes every order through a domestic shipping rate table charges Canadian customers the same flat US rate as Los Angeles — producing direct financial losses when shipping a package to Toronto for $12 that actually costs $34. The store either absorbs the loss or charges the customer incorrectly. CWE-682 (Incorrect Calculation) applies when a country parameter is accepted by the address form but silently ignored by the shipping calculation. International expansion is invalidated if the first cross-border order ships at a domestic rate.

Add a country branch to the shipping calculation in lib/shipping.ts:

// lib/shipping.ts
async function getShippingRate(
  destination: Address,
  method: ShippingMethod,
  items: OrderItem[]
): Promise<number> {
  if (destination.country === 'US') {
    return getDomesticRate(destination.state, method, items)
  }

  // International: delegate to carrier API for live rates
  const shipment = await easypost.shipment.create({
    to_address: {
      country: destination.country,
      city: destination.city,
      zip: destination.zip,
    },
    parcel: {
      weight: items.reduce((sum, i) => sum + i.weight * i.quantity, 0),
    },
  })
  return Number(shipment.rates[0].rate) * 100
}

If carrier API integration is out of scope, restrict the address form's country dropdown to domestic only rather than silently applying domestic rates to international addresses.