Lean Proof

Q: What is a Claude Code skill and how does the Lean Proof 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 Proof 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: prd-spec · Last updated: 2026-05-30

type:review

USE FOR: writing Lean 4 proofs one tactic at a time, fixing tactic errors by priority, planning sorry placeholders, cleaning a working proof, resolving dependent-type rewriting failures. DO NOT USE FOR: reviewing existing proofs (use @lean-proof-review), project-wide quality assessment (use @lean-quality-engine), minimising an error into a bug report (use @lean-mwe), discovering tactics or API (use @lean-research), authoring new theorem statements (use @lean-specification), repairing toolchains (use @lean-setup). TRIGGERS: prove, tactic, sorry, unsolved goals, motive is not type correct.

About this skill (catalog notes)

Lean Proof includes pricing or quota commentary. The SKILL.md runs to about 844 words, in the catalog's typical mid-range.

Source: github.com/r-irbe/proof-skills
License: Apache-2.0
Original author: r-irbe
Indexed lastmod: 2026-05-30
Catalog position: Product · prd-spec
Indexed related skills: 10

How Lean Proof fits the catalog

Lean Proof sits in the Product category under the prd-spec sub-topic in the ClaudSkills catalog. There are 10 related skills indexed alongside it; comparing a few before installing usually reveals which fits your workflow best.

These notes are auto-generated from features detected in the SKILL.md file and from this catalog's structure — they aren't part of the source repository.

What this skill does

Lean Proof is a community-contributed Claude Code skill in the prd-spec sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/lean-proof/ and loads when your prompt matches the skill's trigger.

Who uses this skill

The Lean Proof 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 117,000+ 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-proof
curl -L https://claudskills.com/skills/lean-proof/SKILL.md \
  -o ~/.claude/skills/lean-proof/SKILL.md

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

Skills live at ~/.claude/skills/lean-proof/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\lean-proof\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 Proof Claude Code skill?

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

What does the Lean Proof 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 Proof skill?

Use Lean Proof when your Claude Code task falls under the Product category — specifically in the prd spec 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 Proof" 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 Proof 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 Proof 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/_overrides/lean-proof/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 Proof [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/lean-proof/

BibTeX

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

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Badge

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