Post-Incident Debrief
VeryGoodOpenSource/vgv-wingspan
Produces a blameless post-incident debrief with timeline, root cause and follow-up actions after an outage, failed release or significant bug, while details are fresh.
Write the canonical engineering record of a fixed bug — root cause, mechanism, fix, validation, and how it slipped through.
Install Post Mortem
$ npx skills add thananon/9arm-skills --skill post-mortem -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install thananon/9arm-skills post-mortem --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/thananon/9arm-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/engineering/post-mortem .claude/skills/post-mortem && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "post-mortem" agent skill from https://github.com/thananon/9arm-skills/tree/main/skills/engineering/post-mortem into .claude/skills/post-mortem/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "post-mortem", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/thananon/9arm-skills/tree/main/skills/engineering/post-mortemType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add thananon/9arm-skills --skill post-mortem -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install thananon/9arm-skills post-mortem --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/thananon/9arm-skills.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/engineering/post-mortem .agents/skills/post-mortem && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "post-mortem" agent skill from https://github.com/thananon/9arm-skills/tree/main/skills/engineering/post-mortem into .agents/skills/post-mortem/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "post-mortem", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add thananon/9arm-skills --skill post-mortem -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install thananon/9arm-skills post-mortem --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/thananon/9arm-skills.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/engineering/post-mortem .cursor/skills/post-mortem && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "post-mortem" agent skill from https://github.com/thananon/9arm-skills/tree/main/skills/engineering/post-mortem into .cursor/skills/post-mortem/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "post-mortem", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/thananon/9arm-skills.git --path skills/engineering/post-mortem--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add thananon/9arm-skills --skill post-mortem -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install thananon/9arm-skills post-mortem --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/thananon/9arm-skills.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/engineering/post-mortem .gemini/skills/post-mortem && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "post-mortem" agent skill from https://github.com/thananon/9arm-skills/tree/main/skills/engineering/post-mortem into .gemini/skills/post-mortem/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "post-mortem", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install thananon/9arm-skills post-mortemInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add thananon/9arm-skills --skill post-mortem -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/thananon/9arm-skills.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/engineering/post-mortem .github/skills/post-mortem && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "post-mortem" agent skill from https://github.com/thananon/9arm-skills/tree/main/skills/engineering/post-mortem into .github/skills/post-mortem/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "post-mortem", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add thananon/9arm-skills --skill post-mortem -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install thananon/9arm-skills post-mortem --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/thananon/9arm-skills.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/engineering/post-mortem .opencode/skills/post-mortem && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "post-mortem" agent skill from https://github.com/thananon/9arm-skills/tree/main/skills/engineering/post-mortem into .opencode/skills/post-mortem/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "post-mortem", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
post-mortem- GitHub stars
- 3.2k
- Token cost
- ~3.4k tokens
- SKILL.md length
- 1,834 words
- Files
- 1
- Skills in repo
- 6
- Repo updated
- First seen
- Licence
- None found
At a glance
Write the canonical engineering record of a fixed bug — root cause, mechanism, fix, validation, and how it slipped through.
- Works in 9 steps: Summary (mandatory) → Symptom → Root cause (mandatory) → …
- The user says write the post-mortem / postmortem / RCA / root cause analysis
- SKILL.md covers When to invoke, When NOT to use, Required inputs — refuse to… and Structure, plus 4 more sections
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
What it does
Post Mortem is an agent skill from thananon/9arm-skills. Write the canonical engineering record of a fixed bug — root cause, mechanism, fix, validation, and how it slipped through. Engineer-audience, code identifiers welcome. Use after a debug session lands a fix, before closing the ticket. Trigger on /post-mortem, when the user says "write the post-mortem / postmortem / RCA / root cause analysis", "document this fix", "write up the root cause", "close out this bug with a writeup", or hands you a fixed-and-validated bug and asks for the writeup.
Its SKILL.md is about 3.4k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.
It sits in DevOps & Cloud, covering Runbooks and postmortems and Root cause analysis.
When your agent uses it
- The user says write the post-mortem / postmortem / RCA / root cause analysis
- Document this fix
- Write up the root cause
- Close out this bug with a writeup
Example prompts
- “write the post-mortem / postmortem / RCA / root cause analysis”
- “document this fix”
- “write up the root cause”
- “/post-mortem”
Workflow steps
9 steps, taken from the step headings in SKILL.md.
- Summary (mandatory)
- Symptom
- Root cause (mandatory)
- Why it produced the symptom
- Fix (mandatory)
- How it was found
- Why it slipped through
- Validation (mandatory)
- Action items / follow-ups
What it can do on your machine
Read from SKILL.md and the folder at commit a1fc303. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Post Mortem loads about 3.4k tokens when it runs. Until then it costs about 127 tokens; SKILL.md has 1,834 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
Without a licence we can't republish the file, so here is its outline and opening line. It has 1,834 words (~3,351 tokens).
“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…”
- name
- post-mortem
Files
Just SKILL.md in skills/engineering/post-mortem of thananon/9arm-skills.
Open the folder on GitHubat commit a1fc303
Compare with similar skills
Post Mortem next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Post Mortem this skillthananon/9arm-skills | 3.2k | — | ~3.4k | Automated safety check: Pass | None | |
| Post-Incident DebriefVeryGoodOpenSource/vgv-wingspan | 109 | — | ~1.9k | Automated safety check: Pass | MIT | |
| Conducting Post Incident Lessons Learnedmukul975/Anthropic-Cybersecurity-Skills | 34k | — | ~1.7k | Automated safety check: Pass | Apache-2.0 | |
| Post Mortemhanamizuki/solopreneur | 152 | — | ~1.7k | Automated safety check: Pass | MIT | |
| Product Lifecycle Learningmagnus919/agent-skills | 113 | — | ~4.7k | Automated safety check: Pass | MIT | |
| Postmortemalirezarezvani/claude-skills | 28k | 2 repos | ~2k | Automated safety check: Pass | MIT |
Similar skills
Conducting Post Incident Lessons Learned
mukul975/Anthropic-Cybersecurity-Skills
Facilitate structured post-incident reviews to identify root causes, document what worked and failed, and produce actionable recommendations to improve future incident response.
Post Mortem
hanamizuki/solopreneur
Trace when a bug was introduced, find the root cause commit, understand why it happened, and produce a structured post-mortem report.
Product Lifecycle Learning
magnus919/agent-skills
Compare intended product outcomes against observed results to close the launch-to-learning loop: collect post-launch evidence, distinguish expected from observed from uncertain from inferred claims…
Postmortem
alirezarezvani/claude-skills
/em:postmortem — Honest analysis of what went wrong. An agent skill from alirezarezvani/claude-skills.
Postmortem
dralgorhythm/claude-agentic-framework
Runs this framework's blameless postmortem workflow — reconstruct the incident timeline from evidence, drive five-whys to a mechanism-level root cause, and produce owner-and-due-date action items…
More from thananon/9arm-skills
Management Talk
thananon/9arm-skills
Rewrite engineer-to-engineer content for engineering-org leadership (VPs, directors, PMs, release managers, execs in an engineering-savvy company) and shape it for the channel it is going to — JIRA…
Qwen Agent
thananon/9arm-skills
Delegate menial, well-scoped coding tasks to a cheap Qwen-backed subagent via the claude-9arm command instead of burning Claude tokens/quota.
Debug Mantra
thananon/9arm-skills
Four-mantra debugging discipline — reproduce, trace the fail path, falsify the hypothesis, cross-reference every breadcrumb.
Qwenchance
thananon/9arm-skills
Keeps a long Claude Code task on-track — breaks out of looping/circular thinking, watches the context budget, bounds internal reasoning, and triggers a clean handoff before the window fills.
Scrutinize
thananon/9arm-skills
Outsider-perspective end-to-end review of a plan, PR, or code change.
Related
Categories
Questions about Post Mortem
What does Post Mortem do?
Write the canonical engineering record of a fixed bug — root cause, mechanism, fix, validation, and how it slipped through. Post Mortem is an agent skill from thananon/9arm-skills. Write the canonical engineering record of a fixed bug — root cause, mechanism, fix, validation, and how it slipped through.
When should I use Post Mortem?
Post Mortem fits situations like: the user says write the post-mortem / postmortem / RCA / root cause analysis; document this fix; write up the root cause; close out this bug with a writeup.
How do I install Post Mortem in Claude Code?
Run `npx skills add thananon/9arm-skills --skill post-mortem -a claude-code`. Or copy the skill folder (skills/engineering/post-mortem in thananon/9arm-skills) into .claude/skills/post-mortem in your project. Claude Code loads it when a task matches its description.
How do I install Post Mortem in Codex?
Run `npx skills add thananon/9arm-skills --skill post-mortem -a codex`. Or copy the skill folder (skills/engineering/post-mortem in thananon/9arm-skills) into .agents/skills/post-mortem in your project. Codex loads it when a task matches its description.
Can I use Post Mortem in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add thananon/9arm-skills --skill post-mortem -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/post-mortem, .gemini/skills/post-mortem, .github/skills/post-mortem and .opencode/skills/post-mortem in your project.
What does Post Mortem need to run?
SKILL.md names no scripts, command-line tools or credentials: Post Mortem is instructions for the agent only.
Does Post Mortem access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Post Mortem safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Post Mortem use?
No licence was found for Post Mortem or its repository. Without one, default copyright applies: ask the author before reusing or redistributing it.
How many tokens does Post Mortem use?
About 3.4k tokens (SKILL.md is roughly 13k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Post Mortem?
Skills that share tags, products or a category with Post Mortem: Post-Incident Debrief (VeryGoodOpenSource/vgv-wingspan, 109 stars), Conducting Post Incident Lessons Learned (mukul975/Anthropic-Cybersecurity-Skills, 34k stars), Post Mortem (hanamizuki/solopreneur, 152 stars) and Product Lifecycle Learning (magnus919/agent-skills, 113 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Post Mortem?
thananon (a GitHub user) maintains it in thananon/9arm-skills, which has 3,208 GitHub stars. The repository holds 6 skills in this directory. The repository was last updated on June 14, 2026.
Source: thananon/9arm-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.