I keep seeing a failure mode in service-oriented systems:

We version code (and sometimes infra), but external system changes (DB, queues, IAM/policies, schema registry, flags) often live as runbooks and “don’t forget” steps.

When they diverge across environments, failures are often silent and only surface later as drift.

Two questions: 1) How do you keep these changes aligned with app versions across environments? 2) Where does it break most often for you: data, messaging, IAM/policy, or config/flags?