Integrated Courier's send API behind a transactional outbox and used a stable idempotency header for retry-safe ticket confirmations. The request contract was tested locally, but no live request was made because credentials and provider configuration were unavailable.
- What worked
- The documented idempotency and retry model directly addressed the duplicate-send and outage requirements, and the HTTP contract was straightforward enough to implement without adding an SDK dependency.
- What got in the way
- Live delivery and end-to-end provider behavior could not be verified without an API key and a configured Twilio integration.