Lean Applied Reasoning

Q: What is a Claude Code skill and how does the Lean Applied Reasoning skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Lean Applied Reasoning is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Product category. Learn more at https://claudskills.com/learn/what-is-skill-md/.

Category: Product · Sub-category: product-misc · Last updated: 2026-05-30

USE FOR: Applied reasoning for intelligence analysis, strategy creation and analysis, brainstorming methodologies, investigative reasoning, and domain-specific decision-making. Use when formalizing strategic frameworks, situational analysis, hypothesis generation workflows, decision-under-uncertainty models, or when connecting theoretical formalization to practical operational contexts. Bridges mathematical formalization to real-world application domains. DO NOT USE FOR: pure intelligence-analysis methodology (use @applied-intelligence-analysis); strategy analysis methodology (use @applied-strategy-analysis); legal reasoning methodology (use @applied-legal-reasoning). TRIGGERS: applied reasoning, intelligence formalisation, strategy formalisation, investigative reasoning, domain-specific reasoning.

Security AStatic scan found no risk patternsHow grading works ›

From the source SKILL.md

Guide to formalizing applied reasoning — from intelligence analysis to strategic decision-making — in Lean 4.

What this skill does

Lean Applied Reasoning is a community-contributed Claude Code skill in the product-misc sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/lean-applied-reasoning/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use when formalizing strategic frameworks, situational analysis, hypothesis generation workflows, decision-under-uncertainty models, or when connecting theoretical formalization to practical operational contexts. Bridges mathematical formalization to real-world application domains.

Who uses this skill

The Lean Applied Reasoning Claude Code skill is built for product managers, product designers, and cross-functional teams planning, shipping, and measuring product features. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 211,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/lean-applied-reasoning
curl -L https://claudskills.com/skills/lean-applied-reasoning/SKILL.md \
  -o ~/.claude/skills/lean-applied-reasoning/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/lean-applied-reasoning/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/lean-applied-reasoning/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\lean-applied-reasoning\SKILL.md on Windows. See the full install guide for step-by-step instructions.

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the Lean Applied Reasoning Claude Code skill?

Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/lean-applied-reasoning/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.

What does the Lean Applied Reasoning skill do?

Is this skill free to install?

Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.

When should I use the Lean Applied Reasoning skill?

Use Lean Applied Reasoning when your Claude Code task falls under the Product category — specifically in the product misc area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Lean Applied Reasoning" or describe the task and let Claude pick). Browse related skills at /category/product/.

What is a Claude Code skill and how does the Lean Applied Reasoning skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Lean Applied Reasoning is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Product category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Source: https://github.com/r-irbe/proof-skills/blob/HEAD/skills/lean-applied-reasoning/SKILL.md
License: Apache-2.0
Author: r-irbe
Website: https://github.com/r-irbe/proof-skills

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA

r-irbe. (2026). Lean Applied Reasoning [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/lean-applied-reasoning/

BibTeX

@misc{lean-applied-reasoning-2026,
  author    = {r-irbe},
  title     = {Lean Applied Reasoning [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/lean-applied-reasoning/}
}

Embed this skill

Promote, attribute, or link this skill from your own README, blog post, or documentation. All three snippets are free to use — no sign-up, no API key. More distribution surfaces →

Badge

[![ClaudSkills](https://claudskills.com/badge/lean-applied-reasoning.svg)](https://claudskills.com/skills/lean-applied-reasoning/?utm_source=badge&utm_medium=readme&utm_campaign=skill_badge)

Security scan

Grade A · scanned 2026-10-25 — free static scan against the OWASP Agentic Skills Top 10.

The scan flagged 1 of 10 categories (filesystem), including lower-severity patterns. Patterns shown inside code fences are weighted as examples rather than instructions — read the grading methodology for what this does and does not guarantee.

✓ Prompt injection
✓ Data exfiltration
✓ Supply chain
✓ Reverse shell
✓ Credentials
✓ Execution
⚠ Filesystem
✓ Persistence
✓ Obfuscation
✓ Network

Show this grade on your repo (click to copy):

[![Security: A](https://img.shields.io/badge/Security-A-2e7d32)](https://claudskills.com/skills/lean-applied-reasoning/#security)

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