post-mortem

post-mortem is a skill for Claude Code, Codex from baphuongna/pi-crew. It costs 14 tokens per session (700 once invoked), scanned A, original, MIT.

An engineering record written after a bug has been fixed. It explains what broke, the confirmed cause, the fix, and how the fix was tested.

In plain words
What is it for?
Use it when a reliable reproduction, known root cause, identified fix, and passing validation are available.
Why use it?
It preserves the reasoning behind a fix so future readers can understand and avoid the same failure.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

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/baphuongna/pi-crew/post-mortem
Any agent
npx skills add baphuongna/pi-crew --skill post-mortem
Clone the repo
git clone --depth 1 https://github.com/baphuongna/pi-crew

Made for: Claude Code, Codex.

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 post-mortem

README.md
[![agentmods](https://agentmods.dev/badge/skills/baphuongna/pi-crew/post-mortem.svg)](https://agentmods.dev/skills/baphuongna/pi-crew/post-mortem)
Your own site
<a href="https://agentmods.dev/skills/baphuongna/pi-crew/post-mortem"><img src="https://agentmods.dev/badge/skills/baphuongna/pi-crew/post-mortem.svg" alt="Measured on agentmods" height="20"></a>
Per session 14 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 700 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 5.1 $0.00014 $0.00700
Opus 5 $0.00007 $0.00350
Sonnet 5 $0.00003 $0.00140
Haiku 4.5 $0.00001 $0.00070

Measured 6d ago against content hash 256a682b0d97, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

post-mortem 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 6d 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/post-mortem/SKILL.md · 97 lines

How it starts

The opening of the file, as written. The whole thing — 97 lines — stays where its author put it; the contents beside it link to each section on GitHub.

post-mortem

The canonical engineering record of a bug fix. Written after debugging lands a real fix.

Required Inputs — Refuse to Draft Without These

  • Reliable repro exists (deterministic or high-rate flake)
  • Root cause is known (mechanism identified, not a hypothesis)
  • Fix is identified (PR / commit / branch)
  • Fix is validated (original repro now passes)

If any missing → list what's missing and stop. Do not draft.

Structure

1. Summary

What broke (user terms), what fixed it (one sentence). JIRA key, PR, owner. A reader who stops here should have the right answer.

2. Symptom

Concrete: test output, error message, log line. No paraphrase. What was actually observed.

3. Root Cause

The actual bug mechanism. Code identifiers welcome — function names, file paths, branch conditions. Walk the cause chain end-to-end.

4. Why It Produced the Symptom

Walk the chain so reader connects symptom to cause. Often non-obvious — bug is in X but visible failure is in Y.

5. Fix

What changed and why this addresses root cause. Link to PR/commit. If a previous fix attempt papered over the symptom, name it and explain what was wrong.

6. How It Was Found

Short. The debugging path:

  • What repro made it deterministic
  • What tools cracked it
  • Hypotheses tried and rejected (with one-line reason each)
  • The single experiment that confirmed the cause

7. Why It Slipped Through

CI gap? Latent code? Workload gap? Incomplete prior fix? Review miss? Be specific.

If honest answer is "no good reason" — say so. Blameless — describe the gap, not the person.

8. Validation

How we know the fix works:

  • Original failing test now passes (test name)
  • Customer workload now completes (workload identifier)
  • Other affected configs/workloads also tested

If only one config validated, say so explicitly.

9. Action Items

What + owner + tracking artifact:

  • Regression test added at . (Owner, test name)
  • CI gap closed: . (Owner, ticket)
  • Doc/runbook updated. (Owner, link)

Read the full file on GitHub · 97 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. 6d ago First seen · 97 lines · 14 tokens per session scan A 256a682b0d97

Subscribe to this mod's changes

post-mortem is a skill published in the GitHub repository baphuongna/pi-crew (51 stars, last pushed yesterday), licensed MIT. It adds 14 tokens to every session and 700 once invoked, about $0.0001 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 2026-08-30.

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