What the on-site widget and the mobile promo views show under a price: every plan the merchant's
policy offers for amount, each with the instalment amount, the first and last instalment, the
fees including VAT and the total payable — quoted from the policy's price list with no customer
data. The checkout quotes the customer's own terms; a plan here is the lowest price the policy lists.

Authenticate with a publishable key (pk_test_… / pk_live_…) in the X-Public-Key header —
safe to embed in a page. Cross-origin requests are allowed. The platform keeps a merchant's quote for an
amount for one minute; like every API response this one is marked uncacheable, and the widget caches per page.
plans is empty when the amount is outside [minAmount, maxAmount] or the account has no active
policy; the widget renders nothing in that case.

Errors: 401 PUBLIC_KEY_REQUIRED | INVALID_PUBLIC_KEY, 400 INVALID_AMOUNT | UNSUPPORTED_CURRENCY, 429.