Real engineering scenarios. Choose a path. See the consequences. Understand the reasoning.
A routine patch update to a date-formatting library changed its locale handling. The change was semver-compliant. Tests passed. The bug shipped to production and silently corrupted date-sensitive financial reports for 12 hours.
The on-call engineer received 400+ alerts per week. When a real incident started — a slow memory leak that would eventually OOM-kill the primary database — the alert was buried in noise. The outage lasted 4 hours. The alert had fired 90 minutes earlier.