Monitor and troubleshoot

Integrations do not fail loudly. They fail at 02:00 in a job nobody watches, and the first symptom is a buyer asking why the invoice price is not the screen price. The worst failure of all is the one where nothing errors because nothing ran — which is why "no file arrived by 03:00" is an alarm you have to build deliberately.

Three things to keep up: a five-minute daily read of the four logs, a triage routine for the handful of failures that account for almost every support case, and somebody who reads the changelog so that a deprecation is a scheduled task rather than a surprise.

• Monitor your integrations — Calls, errors, latency, webhook delivery.
• Common API problems — 401, 403, 429, 422 — and the webhook that never arrives.
• Handling API changes — Deprecations, versions, the changelog.