Let the named customer pay you

With X-Reseller-Customer-Id, this creates an invoice on your own payment gateway (connected under Payments in your business dashboard) and returns its pay page: crypto through Heleket or NOWPayments (method: "crypto"), cards through Stripe Checkout or Payoneer Checkout (method: "card"); one live gateway per rail. The page shows your merchant name, the money goes to your account, and when it arrives we credit the customer's store credit automatically: the exact amount, the whole amount when they overpay, and what actually arrived when a crypto invoice closes short. Amounts are whole cents; sub-floor amounts are raised to the method floor ($3 crypto, $10 card) and one invoice is at most $5,000. Send an Idempotency-Key and a retried request returns the same open invoice. No gateway for that method ⇒ 403 deposits_not_available.

An order can pay for itself. POST /orders for a named customer with method: "crypto" or "card" and short credit still answers 402 customer_credit_insufficient, but with payUrl, depositId, chargeCents (the shortfall raised to the rail's minimum) and shortfallCents added. Send the customer to payUrl: when the money lands, the credit is granted and the order is placed automatically under the same Idempotency-Key, a Telegram customer is told in the store's bot, and GET /deposits/{id} shows for_order: true. Without a gateway for that rail the 402 carries no pay page and the customer needs credit first.