incident-postmortem

A blameless record of a service failure, covering what happened, when it happened, its effects, the underlying causes, and follow-up work. A post-mortem is a review held after an incident; RCA means finding its root cause.

In plain words
What is it for?
Use it after outages, security events, failed deployments, or other incidents to record the timeline, impact, causes, and prevention tasks.
Why use it?
It turns a confusing outage into a shared account of what failed and helps teams improve systems without focusing on individual blame.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/fattain-naime/engineering-docs/incident-postmortem
Any agent
npx skills add fattain-naime/engineering-docs --skill incident-postmortem
Clone the repo
git clone --depth 1 https://github.com/fattain-naime/engineering-docs

Made for: Claude Code, Codex.

Per session 59 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,711 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00059 $0.03711
Opus 5 $0.00030 $0.01855
Sonnet 5 $0.00012 $0.00742
Haiku 4.5 $0.00006 $0.00371

Measured 2d ago against content hash 57681d8a6b4a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

incident-postmortem scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/incident-postmortem/SKILL.md · 270 lines

How it starts

The opening of the file, as written. The whole thing — 270 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Purpose

Produce a blameless post-mortem that captures what happened, why it happened at every causal layer, and what specific, measurable actions will prevent recurrence.

A post-mortem that blames a person is a post-mortem that will not be written honestly next time. The goal is to find and fix system failures, not to assign individual culpability.

Input

Works best with: A description of the incident. Also valuable: Timeline of events, monitoring data, the alert that fired, what was done to mitigate, any on-call notes from the incident.

Example invocation: Write a post-mortem for the incident on 2026-07-09 where the payment gateway returned 500 errors for 22 minutes affecting 8% of payment attempts. The root cause was a database connection pool exhaustion triggered by a slow query introduced in the v2.3.0 deployment 2 hours earlier.

Key Concepts

Blameless Culture (Google SRE)

People do not cause incidents. Systems do. When an engineer makes a mistake that leads to an incident, the real questions are:

  • Why did the system allow that mistake to have this impact?
  • What alerting, testing, or deployment control would have prevented it?
  • What process would have caught this before production?

Blameless does not mean consequence-free. It means the post-mortem focuses on systemic remediation, not individual punishment.

Conflict Resolution

When your analysis conflicts with the user's stated preference:

  1. Present both positions — show your analysis and their preference side by side
  2. Explain the trade-off — what are the consequences of each choice?
  3. Recommend with reasoning — state your recommendation and why
  4. Respect the user's decision — they own the final call
  5. Document the decision — record it as an [owner-specified] override with reasoning

Document Length

Target length: 5-8 pages (excluding appendices).

Shorter is better than longer. If the document exceeds the target, check for:

  • Redundant content that can be cut
  • Overly verbose explanations
  • Content that belongs in a separate reference document
  • Material the agent already knows (don't explain what HTTP is)

Read the full file on GitHub · 270 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 270 lines · 59 tokens per session scan A 57681d8a6b4a

Subscribe to this mod's changes

incident-postmortem is a skill published in the GitHub repository fattain-naime/engineering-docs (4 stars, last pushed 17d ago), licensed MIT. It adds 59 tokens to every session and 3,711 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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