Claude Code Thinking Skills is a catalogue of 28 portable skills that give coding agents structured procedures for reasoning about decisions, diagnosis, risk, strategy, and related problems. It is intended for Claude Code, GitHub Copilot, Codex, Cursor, and other tools that support Agent Skills.
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 tjboudreaux/cc-thinking-skills --skill thinking-pre-mortemgit clone --depth 1 https://github.com/tjboudreaux/cc-thinking-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/tjboudreaux/cc-thinking-skills/thinking-pre-mortem)<a href="https://agentmods.dev/skills/tjboudreaux/cc-thinking-skills/thinking-pre-mortem"><img src="https://agentmods.dev/badge/skills/tjboudreaux/cc-thinking-skills/thinking-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/tjboudreaux/cc-thinking-skills/thinking-pre-mortem"><img src="https://agentmods.dev/badge/skills/tjboudreaux/cc-thinking-skills/thinking-pre-mortem.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk pass
- NVIDIA SkillSpector warn
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 44 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.
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 | $0.00038 | $0.00819 |
| Opus 5 | $0.00019 | $0.00409 |
| Sonnet 5 | $0.00008 | $0.00164 |
| Haiku 4.5 | $0.00004 | $0.00082 |
Grade A, and why
thinking-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 10d 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 — 46 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Pre-Mortem Analysis
Core rule: Prospective hindsight beats "what could go wrong?" Assume the plan has already failed (past tense), generate concrete failure paths, reverse them into prevention requirements, and bind each top path to a verifiable plan change.
When to Use
- Before kickoff, major technical commitment, high-risk sprint work, launch, or release.
- After a plan looks solid but before execution, especially when optimism or overconfidence is likely.
- When a decision is costly to reverse and risks are still implicit rather than enforced.
When NOT to Use
- Work is small, local, and cheaply reversible — skip the ceremony.
- You are mid-incident under time pressure — act now (OODA / scientific method); pre-mortem is pre-execution.
- You would only emit generic risks ("scope creep", "requirements unclear") that do not bind to this plan.
- Risks are already enforced by live gates (CI, canary, rollback, alerts) with no residual unlisted path.
- A mature risk register already covers the same specific failure paths with owners and checks.
Procedure
- Set the failure frame in past tense: "It is [post-deadline date]. The plan failed: [rollback / data loss / no adoption / SLA breach]." Explaining a happened failure is required; predicting one is not enough.
- Generate failure reasons before filtering: sweep technical, process, assumptions, dependencies/external, and people. Force a second pass: "What did the plan most need to be true that was not?" Collect breadth first (aim for many distinct reasons); do not rank mid-sweep.
- Prioritize: group by theme; score likelihood × impact; keep the top 3–5 concrete risks (drop generics that do not bind).
- Failure-first reverse analysis (absorbed reverse path): for each top risk, (a) restate the failed outcome in past tense, (b) list necessary/enabling conditions that had to be true for that failure, (c) invert each condition into a verifiable prevention requirement (avoid/require rule + check), (d) bind owner, verification checkpoint, and ship/stage gate.
- Mitigate and update the plan: for each top risk, attach mitigation steps, spike/contingency if needed, and the reverse-analysis prevention requirements as explicit plan gates. A pre-mortem with no plan change is incomplete.
- Stop when top risks each have a bound mitigation or prevention gate, or when further reasons are only generic restatements — then ship the updated plan, do not keep brainstorming.
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.
- 10d ago First seen · 46 lines · 38 tokens per session scan A a38aff195dcd
thinking-pre-mortem is a skill published in the GitHub repository tjboudreaux/cc-thinking-skills (1,293 stars, last pushed 1mo ago), licensed MIT. It adds 38 tokens to every session and 819 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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