Simulate inbound transfer on a Virtual Account

Simulate an inbound fiat transfer against a Virtual Account, for testing webhook and reconciliation flows. Sandbox / non-production only; returns 404 in production-live. Set the type field in the request body to choose the transfer rail: bankUs (network ach, wire or rtp) or bankIban (network swift). Not every rail is available on every Virtual Account; one whose provider does not offer the requested rail refuses the request. The Idempotency-Key header is required and is deduplicated before the provider is called: a retry carrying the same key replays the recorded response and never reaches the provider again. A retry with a new key is a new request, and on a Virtual Account whose provider models no idempotency key of its own it books a second credit.