State Machine: PayIn

State Machine: PayIn (real, API-facing)

Note: process, processing, in_mempool are transitional and may be skipped in responses. Merchants should rely mainly on: waiting_asset_select, pending, confirm_check, paid*, cancel, expired, system_fail.

Main lifecycle

Create Order
  -> process
     # Order created and initialized (often very short-lived)

process
  -> waiting_asset_select
     # Multiple payment assets are available (or asset must be chosen in H2H)
  -> pending
     # Single asset resolved automatically (address assigned / verified)
  -> system_fail
     # Internal error during initialization

waiting_asset_select
  -> pending
     # Asset selected:
     # - Hosted: user selects on payment page (automatic)
     # - H2H: merchant calls Select Asset endpoint
  -> cancel
     # Available in both Hosted and H2H flows.
     # User may cancel the payment from the terminal / payment page.
  -> expired
     # Lifetime timer reached before asset selection/payment
  -> system_fail
     # Internal error

pending
  -> in_mempool
     # Transaction detected in mempool (primarily BTC; may be skipped on other networks)
  -> confirm_check
     # Transaction detected on-chain (can come directly, skipping mempool)
  -> cancel
     # Available in both Hosted and H2H flows.
     # The user may cancel the payment from the terminal / payment page
  -> expired
     # Lifetime timer reached without valid payment
  -> system_fail
     # Internal error

in_mempool
  -> confirm_check
     # Mempool -> block inclusion / on-chain visibility
     # mempool event is stored, but no finalization happens here
  -> system_fail
   # Transaction dropped from mempool
   # OR replaced (RBF)
   # OR disappeared due to mempool eviction

confirm_check
  -> paid
     # actual within ±accuracy_payment_percent of expected
  -> paid_over
     # actual above allowed tolerance
  -> paid_less
     # actual below allowed tolerance
  -> system_fail
     # Reorg / chain error / internal failure

Webhooks

Webhook notifications are sent on every order status transition, including both transitional and settlement states. Detailed information about which statuses are terminal, and how webhooks behave is described in the Webhooks section.