Start with the contract
Before changing an integration, write down what enters the system, what leaves it, and which failures are expected. A narrow contract gives both the code and its operators something stable to reason about.
Keep the first signal close
Log or measure a failed validation where it happens. That small decision turns a vague downstream symptom into a useful starting point for investigation.
Make recovery explicit
Retries, fallbacks, and dead-letter handling should be visible choices rather than accidental side effects. The happy path stays simple, and the failure path stays explainable.