postmortem

postmortem is a skill for Claude Code from flonat/flonat-research. It costs 40 tokens per session (1,557 once invoked), scanned A, original, MIT.

A structured retrospective for examining an incident, mistake, rollback, near-miss, or stuck work session.

In plain words
What is it for?
Use it to record facts, reconstruct the timeline, identify root causes, and improve procedures or documentation.
Why use it?
It turns what went wrong into documented causes and preventive changes instead of leaving the same problem likely to recur.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: mentions CLAUDE.md; names the AskUserQuestion tool.

Good fit Use it to record facts, reconstruct the timeline, identify root causes, and improve procedures or documentation.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/flonat/flonat-research/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 flonat/flonat-research --skill postmortem
Clone the repo
git clone --depth 1 https://github.com/flonat/flonat-research

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/flonat/flonat-research/postmortem.svg)](https://agentmods.dev/skills/flonat/flonat-research/postmortem)
Your own site
<a href="https://agentmods.dev/skills/flonat/flonat-research/postmortem"><img src="https://agentmods.dev/badge/skills/flonat/flonat-research/postmortem.svg" alt="Measured on agentmods" height="20"></a>
Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,557 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: 1 finding, 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 183
    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 $0.00040 $0.01557
Opus 5 $0.00020 $0.00779
Sonnet 5 $0.00008 $0.00311
Haiku 4.5 $0.00004 $0.00156

Measured 4d ago against content hash b5d596654160, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, 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 4d 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/postmortem/SKILL.md · 202 lines

How it starts

The opening of the file, as written. The whole thing — 202 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Lessons Learned: Structured Retrospective

Analyse incidents using a structured framework, identify root causes, and encode preventive measures directly into skills, guards, or documentation. The goal is systematic improvement, not blame.

When to Use

  • After incidents, mistakes, rollbacks, or near-misses
  • When the user says "what went wrong", "lessons learned", "post-mortem", "retrospective", or "how do we prevent this"
  • After a stuck session where significant time was lost
  • After a wrong-approach event (plan existed but execution diverged)

Process

Phase 1: Incident Definition

Capture the facts first, analysis later.

## Incident Summary

**What happened:** [Factual description]
**When:** [Date/time]
**Impact:** [What was affected, scope]
**Resolution:** [How it was fixed/rolled back]
**Time to resolution:** [How long to fix]

Phase 2: Timeline Reconstruction

Build a chronological sequence of events:

Time Action Actor Outcome
HH:MM [What was done] [Claude/User] [Result]

Key questions:

  • What was the trigger?
  • Where did the sequence diverge from expected?
  • What was the point of no return?

Phase 3: Root Cause Analysis (5 Whys)

1. Why did [incident] happen?
   → Because [immediate cause]

2. Why did [immediate cause] happen?
   → Because [deeper cause]

3. Why did [deeper cause] happen?
   → Because [systemic issue]

4. Why did [systemic issue] exist?
   → Because [process gap]

5. Why did [process gap] exist?
   → Because [root cause]

Stop when you reach a cause that can be addressed by a concrete change to the system (skill, rule, hook, doc).

Phase 4: Contributing Factors

Identify all factors, not just the root cause:

Category Factor Contribution
Process Missing checkpoint, unclear workflow [How it contributed]
Communication Ambiguous instructions, assumed consent [How it contributed]
Technical Missing guard, no validation [How it contributed]
Context Session continuation, prior assumptions [How it contributed]
Human Fatigue, time pressure, overconfidence [How it contributed]

Read the full file on GitHub · 202 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. 4d ago First seen · 202 lines · 40 tokens per session scan A b5d596654160

Subscribe to this mod's changes

postmortem is a skill published in the GitHub repository flonat/flonat-research (132 stars, last pushed 13d ago), licensed MIT. It adds 40 tokens to every session and 1,557 once invoked, about $0.0002 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.

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