Multi-currency

Cartwright has two layers of currency support:

1. Display only (currencySwitcher) — show prices in the customer's currency, but still charge in the base currency.
2. True multi-currency (multiCurrency) — charge the customer in their selected currency and record it on the order.

Base currency & rate table

Prices are stored as base-currency minor units (øre for DKK). The base currency and the static rate table live in brand.config.ts:

policies: {
  currency: "DKK",
  supportedCurrencies: {
    DKK: { rate: 1, label: "Danske kroner" },
    EUR: { rate: 0.134, label: "Euro" },
    USD: { rate: 0.145, label: "US Dollar" },
  },
}

Rates are unit-per-1-base-unit (1 DKK = 0.134 EUR); the base currency must be rate: 1. Update them manually, or enable fxAutoUpdate to refresh them daily from the ECB feed into a DB override (read as dbRate ?? staticAnchor).

Enable it

1. Add ≥2 entries to supportedCurrencies.
2. Turn on currencySwitcher in /admin/features (display only).
3. Turn on multiCurrency to charge in the selected currency (depends on currencySwitcher, needs ≥2 currencies).
4. Run the migration first — Order gains currency + fxRate:

   pnpm db:push

5. Your Stripe account must support the presentment currencies.

At checkout

getCheckoutCurrency() resolves the presentment currency, convertMinor() (lib/money.ts) converts the total, the Stripe PaymentIntent is created in that currency, and the order snapshots currency + fxRate. Display and charge share one conversion path, so the shown price always equals the charged price. The confirmation email renders in the order's currency, and the Stripe webhook verifies the paid amount against the snapshot.

Limits

• 2-decimal currencies only (DKK/EUR/USD/GBP/SEK/NOK); a zero-decimal currency throws a guard rather than silently mis-charging.
• Partial refunds in a non-base currency need conversion (full refunds are fine).