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.
npx skills add hugobowne/show-us-your-agent-skills --skill pre-mortemgit clone --depth 1 https://github.com/hugobowne/show-us-your-agent-skillsWrote 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.
[](https://agentmods.dev/skills/hugobowne/show-us-your-agent-skills/pre-mortem)<a href="https://agentmods.dev/skills/hugobowne/show-us-your-agent-skills/pre-mortem"><img src="https://agentmods.dev/badge/skills/hugobowne/show-us-your-agent-skills/pre-mortem/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.
<a href="https://agentmods.dev/skills/hugobowne/show-us-your-agent-skills/pre-mortem"><img src="https://agentmods.dev/badge/skills/hugobowne/show-us-your-agent-skills/pre-mortem.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00041 | $0.02912 |
| Opus 5 | $0.00020 | $0.01456 |
| Sonnet 5 | $0.00008 | $0.00582 |
| Haiku 4.5 | $0.00004 | $0.00291 |
Grade A, and why
pre-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 12d 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.
How it starts
The opening of the file, as written. The whole thing — 301 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Project: honnibal/claude-skills. "Claude skills I'm experimenting with. Please review carefully before use."
License: MIT License. Full license text is in
LICENSEalongside this file.Snapshot: Frozen copy of
pre-mortem.md.txtas of 2026-05-22. The maintained version lives upstream and may have evolved since this snapshot.
Pre-Mortem: Future Bug Post-Mortems
You are now in pre-mortem mode. Your job is to read production code, identify areas of fragility and implicit assumptions, and then write realistic post-mortem reports for bugs that haven't happened yet — but plausibly could, given the kind of changes a future developer might reasonably make.
This is not a bug hunt. The code may be perfectly correct today. You're looking for places where the code is fragile against future edits: places where a developer who doesn't have full context could make a seemingly reasonable change that breaks something in a non-obvious way.
Scope
$ARGUMENTS
- If the user names specific files or directories, scope your analysis to those.
- If no argument is given, look at the project's source layout and use
AskUserQuestionto agree on a starting scope. Pick a module or package with meaningful logic — don't try to cover everything at once. - Focus on production code. Config files, migrations, and boilerplate are out of scope unless they contain logic that other code depends on.
Workflow
-
Read deeply. Read the files in scope carefully. Don't skim — you need to understand data flow, state management, implicit invariants, and the relationships between components. Read callers and callees, not just the file in isolation.
-
Identify fragility. Look for the patterns described in the catalogue below. For each one you find, ask: "What change would a reasonable developer make here that would break this?" If you can't imagine a plausible edit that causes a problem, move on — not everything is fragile.
What ships with it
3 files 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.
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.
- 12d ago First seen · 301 lines · 41 tokens per session scan A 538f3ee362ef
pre-mortem is a skill published in the GitHub repository hugobowne/show-us-your-agent-skills (67 stars, last pushed 1mo ago), licensed MIT. It adds 41 tokens to every session and 2,912 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 2026-08-30.
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