A deterministic gate in front of every destructive storage operation
Early in the platform's life, an object-storage incident took media offline. I traced it, restored service, and then sat with the more uncomfortable question: the code had done exactly what it was told, and what it was told was wrong. No amount of care on my part would guarantee that never happened again, because the failure mode was a correct-looking instruction issued against the wrong target.
So I stopped treating it as a mistake and treated it as a missing structure. Every operation that can delete or overwrite media now passes through a gate that verifies the target against expected state before anything is touched. If the check does not pass, the operation refuses and reports; it does not proceed and log a warning. The gate is deterministic code, not a convention, not a runbook step, and not a comment asking the next person to be careful.
Alongside it: encrypted off-site backups on a schedule, and a restore I have actually tested rather than assumed.