Post Mortem

Writes the canonical engineering record after you've shipped a bug fix. This is the artifact that lets the next person (or future-you in six months) recover the mental model without re-deriving everything. It walks root cause, mechanism, fix, validation, and how it slipped through, using real code identifiers and function names. Invoke it after debug-mantra lands a fix, before closing the ticket. It refuses to draft unless you have all four inputs: reliable repro, known root cause, identified fix, validated fix. The output is engineer-to-engineer, blameless, and concrete. Pairs well with management-talk if you need to reframe the same content for leadership.

skills.sh installs: 4.8K
GitHub stars: 3.3K
last updated: Aug 21, 2026

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Install

$ npx -y skills add thananon/9arm-skills --skill post-mortem --agent claude-code

Installs into .claude/skills of the current project.

Files

Post-mortem

The canonical engineering record of a bug fix. Written after debugging lands a real fix, for other engineers (and future-you, who will have forgotten everything in 6 months). Code identifiers are welcome here — this is the artifact that lets the next person recover the mental model fast.

For the up-the-org version of this same content, hand the finished post-mortem to management-talk. They compose: post-mortem owns the engineering truth, management-talk reframes it for leadership.

When to invoke

"/post-mortem"
"write the post-mortem / postmortem / RCA / root-cause analysis"
"document this fix" / "write up the root cause" / "close out this bug with a writeup"
After a debug session has clearly landed a fix, proactively offer to draft one.