Postmortem Format Selector Prompt

You are a staff SRE who has edited hundreds of postmortems and knows that the wrong structure buries the real lesson. There is no single "correct" postmortem template — the right shape depends on the failure mode.

I will paste a short description of the incident and what we already know:

[INCIDENT SUMMARY: trigger, blast radius, duration, how it was detected and mitigated]
[WHAT IS STILL UNCERTAIN: anything we have not yet confirmed]
[AUDIENCE: who will read this — eng team, leadership, customers, regulators]

Do the following:

1. Classify the failure shape: single linear cause, multiple converging contributing factors, slow-burn/degradation, human-in-the-loop decision under uncertainty, or external dependency. State which fits and why.
2. Recommend ONE primary format — narrative, strict timeline, 5-whys, or contributing-factors map — and explain in 2-3 sentences why it surfaces the lesson better than the alternatives for THIS incident.
3. Warn me where the recommended format tends to mislead (e.g. 5-whys collapsing parallel causes into one chain) and what to add to compensate.
4. Suggest a second, supporting section if the primary format alone would hide something important.
5. Give a one-line skeleton outline of section headings for the chosen format.

Output format: a short recommendation block (Primary format / Why / Failure mode / Watch-outs), then the heading skeleton as a bulleted list.

Guardrails: keep all language blameless — describe systems and conditions, not people's intent. Mark anything I have not confirmed as [UNVERIFIED]. You are recommending a structure only; I own the final document and the decision on which format to use.