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Agent skill

Thinking Pre Mortem

by tjboudreaux in tjboudreaux/cc-thinking-skills

Before committing to a plan or launch, assume it already failed and reason backward through concrete causes — convert failure paths into mitigations, gates, and stop checks.

MITAuto-check passed

Install Thinking Pre Mortem

skills CLI
$ npx skills add tjboudreaux/cc-thinking-skills --skill thinking-pre-mortem -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install tjboudreaux/cc-thinking-skills thinking-pre-mortem --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/tjboudreaux/cc-thinking-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/thinking-pre-mortem .claude/skills/thinking-pre-mortem && rm -rf skills-src

Use ~/.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/

Facts

Skill name
thinking-pre-mortem
GitHub stars
1.6k
Token cost
~926 tokens
SKILL.md length
495 words
Files
1
Skills in repo
26
Repo updated
First seen
Licence
MIT

At a glance

Before committing to a plan or launch, assume it already failed and reason backward through concrete causes — convert failure paths into mitigations, gates, and stop checks.

  • Works in 6 steps: Set the failure frame in past tense: "It… → Generate failure reasons before… → Prioritize: group by theme; score… → …
  • SKILL.md covers When to Use, When NOT to Use, Procedure and Output, plus 1 more section
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Thinking Pre Mortem is an agent skill from tjboudreaux/cc-thinking-skills. Before committing to a plan or launch, assume it already failed and reason backward through concrete causes — convert failure paths into mitigations, gates, and stop checks.

Its SKILL.md is about 930 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

The repository describes itself as: 28 eval-informed mental models and critical-thinking skills for Claude Code, GitHub Copilot, Codex, Cursor, and other Agent Skills-compatible tools. The licence is MIT.

Example prompts

  • “/thinking-pre-mortem”

Workflow steps

6 steps, taken from the first numbered list in SKILL.md.

  1. Set the failure frame in past tense: "It is [post-deadline date]. The plan failed: [rollback / data loss / no adoption / SLA breach]."…
  2. Generate failure reasons before filtering: sweep technical, process, assumptions, dependencies/external, and people. Force a second pass…
  3. Prioritize: group by theme; score likelihood × impact; keep the top 3–5 concrete risks (drop generics that do not bind).
  4. Failure-first reverse analysis (absorbed reverse path): for each top risk, (a) restate the failed outcome in past tense, (b) list…
  5. Mitigate and update the plan: for each top risk, attach mitigation steps, spike/contingency if needed, and the reverse-analysis prevention…
  6. Stop when top risks each have a bound mitigation or prevention gate, or when further reasons are only generic restatements — then ship the…

What it can do on your machine

Read from SKILL.md and the folder at commit 7b8fece. 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

Thinking Pre Mortem loads about 926 tokens when it runs. Until then it costs about 48 tokens; SKILL.md has 495 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~48
When it runs · the whole SKILL.md, loaded when a task matches
~926

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

The full file from tjboudreaux/cc-thinking-skills at commit 7b8fece, republished under its MIT licence (© tjboudreaux). 495 words, ~926 tokens.

Download SKILL.mdSave it as .claude/skills/thinking-pre-mortem/SKILL.md (or your agent's skills folder).
name
thinking-pre-mortem
description
Before committing to a plan or launch, assume it already failed and reason backward through concrete causes — convert failure paths into mitigations, gates, and stop checks.
disable-model-invocation
true

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

  1. 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.
  2. 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.
  3. Prioritize: group by theme; score likelihood × impact; keep the top 3–5 concrete risks (drop generics that do not bind).
  4. 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.
  5. 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.
  6. 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.
Show full SKILL.md (128 more words)Show less

Output

  1. Failure scenario — past-tense disaster frame with date and failed outcome.
  2. Failure reasons — unfiltered list, then prioritized top 3–5 with likelihood × impact.
  3. Reverse paths — for each top risk: necessary conditions → inverted prevention requirements.
  4. Mitigations — owner, verification checkpoint, ship/stage gate per top risk.
  5. Plan deltas — concrete tasks, spikes, contingencies, and gates added to the plan.

Verification

  • Falsify/stop: if no plan-specific failure path can be stated in past tense with necessary conditions, stop — you are generating theater, not risk. If a "mitigation" has no verification checkpoint, it is not done.
  • Over-application guard: do not pre-mortem reversible chores, mid-incident firefighting, or systems that already enforce the same paths. Do not leave abstract risks as "mitigate later"; either invert them into gates or drop them as non-actionable.

© tjboudreaux, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/thinking-pre-mortem of tjboudreaux/cc-thinking-skills.

Open the folder on GitHubat commit 7b8fece

Compare with similar skills

Thinking Pre 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.

Thinking Pre Mortem compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Thinking Pre Mortem this skilltjboudreaux/cc-thinking-skills1.6k—~926Automated safety check: PassMIT
Commitsickn33/agentic-awesome-skills47k2 repos~1.3kAutomated safety check: PassMIT
Commitdavila7/claude-code-templates32k3 repos~730Automated safety check: PassMIT
Commitwindmill-labs/windmill18k—~447Automated safety check: PassCustom licence
Commitccusage/ccusage19k—~722Automated safety check: PassCustom licence
CommitsJetBrains/intellij-community21k—~589Automated safety check: PassCustom licence

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Questions about Thinking Pre Mortem

What does Thinking Pre Mortem do?

Before committing to a plan or launch, assume it already failed and reason backward through concrete causes — convert failure paths into mitigations, gates, and stop checks. Thinking Pre Mortem is an agent skill from tjboudreaux/cc-thinking-skills. Before committing to a plan or launch, assume it already failed and reason backward through concrete causes — convert failure paths into mitigations, gates, and stop checks.

How do I install Thinking Pre Mortem in Claude Code?

Run `npx skills add tjboudreaux/cc-thinking-skills --skill thinking-pre-mortem -a claude-code`. Or copy the skill folder (skills/thinking-pre-mortem in tjboudreaux/cc-thinking-skills) into .claude/skills/thinking-pre-mortem in your project. Claude Code loads it when a task matches its description.

How do I install Thinking Pre Mortem in Codex?

Run `npx skills add tjboudreaux/cc-thinking-skills --skill thinking-pre-mortem -a codex`. Or copy the skill folder (skills/thinking-pre-mortem in tjboudreaux/cc-thinking-skills) into .agents/skills/thinking-pre-mortem in your project. Codex loads it when a task matches its description.

Can I use Thinking Pre 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 tjboudreaux/cc-thinking-skills --skill thinking-pre-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/thinking-pre-mortem, .gemini/skills/thinking-pre-mortem, .github/skills/thinking-pre-mortem and .opencode/skills/thinking-pre-mortem in your project.

What does Thinking Pre Mortem need to run?

SKILL.md names no scripts, command-line tools or credentials: Thinking Pre Mortem is instructions for the agent only.

Does Thinking Pre 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 Thinking Pre 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 Thinking Pre Mortem use?

Thinking Pre Mortem is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Thinking Pre Mortem use?

About 926 tokens (SKILL.md is roughly 3.7k 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 Thinking Pre Mortem?

Skills that share tags, products or a category with Thinking Pre Mortem: Commit (sickn33/agentic-awesome-skills, 47k stars), Commit (davila7/claude-code-templates, 32k stars), Commit (windmill-labs/windmill, 18k stars) and Commit (ccusage/ccusage, 19k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Thinking Pre Mortem?

tjboudreaux (a GitHub user) maintains it in tjboudreaux/cc-thinking-skills, which has 1,612 GitHub stars. The repository holds 26 skills in this directory. The repository was last updated on August 7, 2026.

Source: tjboudreaux/cc-thinking-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.