postmortem

postmortem is a skill for Claude Code from Kevin-Liu-01/Agent-Machines. It costs 57 tokens per session (2,111 once invoked), scanned A, original, MIT.

A structured process for investigating and documenting a production incident, such as an outage, financial loss, or exploited security problem.

In plain words
What is it for?
Use it to build an incident timeline, measure impact, verify the fix, and record follow-up work.
Why use it?
It replaces guesswork and blame with evidence about what happened, why it happened, and how to prevent it happening again.

Skill for Claude Code

Written for Claude Code: $ARGUMENTS substitution.

Good fit Use it to build an incident timeline, measure impact, verify the fix, and record follow-up work.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/kevin-liu-01/agent-machines/postmortem
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.

Any agent
npx skills add Kevin-Liu-01/Agent-Machines --skill postmortem
Clone the repo
git clone --depth 1 https://github.com/Kevin-Liu-01/Agent-Machines

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for postmortem

README.md
[![agentmods](https://agentmods.dev/badge/skills/kevin-liu-01/agent-machines/postmortem/github.svg)](https://agentmods.dev/skills/kevin-liu-01/agent-machines/postmortem)
Your own site
<a href="https://agentmods.dev/skills/kevin-liu-01/agent-machines/postmortem"><img src="https://agentmods.dev/badge/skills/kevin-liu-01/agent-machines/postmortem/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for postmortem

Your own site · 80×15
<a href="https://agentmods.dev/skills/kevin-liu-01/agent-machines/postmortem"><img src="https://agentmods.dev/badge/skills/kevin-liu-01/agent-machines/postmortem.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 57 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,111 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 2 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Excessive Agency · line 34
    Skill grants unrestricted tool access without appropriate constraints. An agent with unfettered tool access can perform arbitrary actions including file modification, network requests, and code execution.
    Fix: Restrict tool access to only the tools required for the skill's stated purpose. Use an explicit allowlist rather than granting blanket access.
  • medium Excessive Agency · line 115
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
How audits are shown
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 5.1 $0.00057 $0.02111
Opus 5 $0.00028 $0.01056
Sonnet 5 $0.00011 $0.00422
Haiku 4.5 $0.00006 $0.00211

Measured 9d ago against content hash b39e4ceb71c3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

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 9d 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.

knowledge/skills/postmortem/SKILL.md · 245 lines

How it starts

The opening of the file, as written. The whole thing — 245 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Postmortem

Structured incident response. Investigate first, write second, verify third.

When to use

  • Production outage or degradation
  • Financial loss (billing bugs, fraud, credit abuse)
  • Security incident (unauthorized access, data leak, bot abuse)
  • Silent failure discovered after the fact (broken integration, dead code path)
  • Any event where the team needs a shared written record of what happened

Philosophy

A postmortem is a forensic document, not a blame report. It answers:

  1. What happened? (timeline, evidence, impact)
  2. Why did it happen? (root causes, not symptoms)
  3. How do we know the fix works? (verification queries, not vibes)
  4. How do we prevent recurrence? (structural fixes, not patches)

Every claim must be backed by data. "We think X" is not acceptable. "Query Y returned Z, which proves X" is acceptable.

Workflow

Phase 1: Investigate

Gather evidence before forming theories. Use every tool available.

Database queries (/db skill):

  • Query production data to quantify impact (how many users, how much money, what time range)
  • Cross-reference tables to find patterns (which accounts, what behavior, what correlation)
  • Always use --readonly and --env prod (only when the user confirms production)
  • Save the queries in the postmortem so anyone can re-run them

Git history (git log, git blame):

  • Build a commit timeline for the affected code paths
  • Identify who changed what and when (for context, not blame)
  • Find the commit that introduced the bug vs. commits that tried to fix it
  • Use git log --format="%h %ad %an %s" --date=short for clean timelines

External service dashboards (Stripe, Clerk, Vercel, AWS):

  • Use MCP tools when available (Stripe MCP, Supabase MCP, etc.)
  • Use CLI tools (gh, aws, stripe) when MCP is not available
  • Screenshot or copy dashboard data as evidence

Code reading:

  • Trace the full code path from entry point to failure
  • Read the actual production code, not what you think it does
  • Check for race conditions, silent error swallowing, missing validation
  • Verify claims against the code ("the threshold is 90" -- is it really?)

Read the full file on GitHub · 245 lines

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. 9d ago First seen · 245 lines · 57 tokens per session scan A b39e4ceb71c3

Subscribe to this mod's changes

postmortem is a skill published in the GitHub repository Kevin-Liu-01/Agent-Machines (29 stars, last pushed today), licensed MIT. It adds 57 tokens to every session and 2,111 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 2026-09-03.

Related

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