principle-postmortemlisted

# Postmortem Incidents are inevitable. A postmortem converts failure into systemic learning — the goal is not to assign blame but to close the gap between what the system can do and what the environment demands. The prevent → detect → learn triad is incomplete without this phase. Cross-references: `principle-resiliency` (prevent), `principle-observability#SLI / SLO / Error Budget` (detect / MTTD-MTTR framing), `principle-release-engineering#Rollback` (remediation action items). ## Blameless Culture Blame suppresses signal. When individuals fear punishment, they conceal information, underreport near-misses, and avoid risky-but-necessary work. Blameless postmortems operate from the assumption that everyone acted rationally given the information and tools available to them at the time. Guiding principles: - **"The system allowed it"** — if a person could cause an outage, the system lacked the guardrails to prevent it. The fix belongs in the system, not the person. - **Psychological safety** — participants must feel safe sharing the full sequence of events, including their own mistakes. Facilitation owns this; interrupt any language that assigns personal fault. - **Hindsight bias** — it is easy to see the right move after the fact. Explicitly reconstruct the information available at each decision point; do not evaluate decisions using information that only became visible later. - **Counterfactual fairness** — "if only they had done X" is only valid if X was a realistic, wel