Sandbox only. Simulates an asynchronous bank transition event on a payment session, as if the real bank callback arrived. This lets you drive a pay-in session through its whole lifecycle entirely by API — no Connect / Demo Bank UI — which is the recommended way to run automated tests or load tests against the sandbox.

Scripted flow:

1. Create a session via the standard public API: POST /pis/v2/connect or POST /pis/v2/request-to-pay. No provider selection is needed — the Demo Bank is assigned automatically on the first simulation.
2. Simulate the statuses your integration should handle. Any transition valid in production is accepted, e.g. straight to payment_created, or payment_pending first (a session left there stays pending), then payment_created, payment_unsuccessful (with an optional transfer_reason, e.g. insufficient_funds) or payment_expired. A failed payment can go back to payment_pending (bank retry), as in production.

All side effects (webhooks, notifications) fire exactly as with a real bank callback.

Constraints:

• Not available in production (simulation_not_allowed)
• The session must belong to the authenticated application
• Only status transitions valid in production are accepted (invalid_state_transition) — e.g. payment_created is terminal