Using the wait_event stage, you can wait for an event to be submitted to a running workflow instance before continuing. This is useful for workflows that require user input, such as a manual approval of a transaction. 
---
stages:
- wait_event:
    event: "payout.confirmed"
Events can be then submitted to running workflow instances using the POST /instances/{id}/events endpoint, or manually using fctl: 
fctl orchestration instances send-event 1234-5678-9012-3456 "payout.confirmed"