Writing postmortems REQUIRED BACKGROUND: the skill (hard rules, truth rules, style). Overview Audience: the engineer who hits something similar in a year, not the people in the room. Core principle: facts from evidence, causes from mechanisms, lessons from both, and no names. Classification: historical; once reviewed it is immutable, and corrections are dated addenda. When to invoke, and not Invoke after an incident is resolved, or at a stable milestone of a long one. A defect that reached users and a near miss (a guard caught what review missed) earn the same write-up. Do NOT invoke during t…