"It works" and "it is production-ready" are different claims. The gap between them is where most incidents live. Production readiness is a set of properties you deliberately build in.
Observability
If something breaks at 3 a.m., can you tell what and why? Logs, metrics, and traces are not optional extras — they are how you operate the system at all.
Recoverability
Backups you have never restored are hopes, not backups. Production readiness means tested recovery procedures and a clear understanding of what data loss is acceptable.
Failure behavior
Production systems fail gracefully. They degrade instead of collapsing, retry sensibly, and avoid turning one failure into cascading ones.
Security posture
Least privilege, patched systems, and controlled access are baseline requirements, not enhancements. Security added later is always more expensive.
Ownership and documentation
A production system has an owner and a runbook. When the person who built it is on vacation, someone else can still operate it.
Production readiness is unglamorous. It is also the difference between confidence and firefighting.