Production code should never depend on the attention of "the oldest guy in the office". We used to have methods not to break stuff: extensive automated testing,

Production code should never depend on the attention of "the oldest guy in the office". We used to have methods not to break stuff: extensive automated testing, monitoring, QA, canary deployments, A/B testing. And, ultimately, a rollback plan. Building production-grade application should not be a one-man (or one-agent) job. Back in the pre-AI era software also used to break when you did not have proper testing and release processes.