A collection of Lean 4 tools for drafting, proving, checking, reviewing, refactoring, shortening, and learning about formal proofs. Lean 4 is a programming language and proof checker for precise mathematics.

Use it to turn claims into Lean code, prove or disprove them, diagnose errors, review or refactor proofs, shorten working proofs, and save progress.

It brings related proof-development tasks into one add-on instead of requiring separate tools for each stage. It can use the Lean language service when available and fall back to scripts.

lean4 — Plugin for Claude Code by cameronfreer/lean4-skills

Install

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.

Clone the repo

git clone --depth 1 https://github.com/cameronfreer/lean4-skills

Made for: Claude Code.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/plugins/cameronfreer/lean4-skills/lean4/github.svg)](https://agentmods.dev/plugins/cameronfreer/lean4-skills/lean4)

Your own site

<a href="https://agentmods.dev/plugins/cameronfreer/lean4-skills/lean4"><img src="https://agentmods.dev/badge/plugins/cameronfreer/lean4-skills/lean4/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.

Your own site · 80×15

<a href="https://agentmods.dev/plugins/cameronfreer/lean4-skills/lean4"><img src="https://agentmods.dev/badge/plugins/cameronfreer/lean4-skills/lean4.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session not measured What this adds to a session before it is invoked.

When invoked not measured The manifest loads nothing itself; its 1 skill, 12 commands, 4 agents, 3 hooks cost 423 tokens a session between them.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Security

Grade A, and why

lean4 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 19d 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.

plugins/lean4/.claude-plugin/plugin.json · 7 lines

What it actually says

{
  "name": "lean4",
  "version": "4.11.3",
  "description": "Unified Lean 4 plugin (draft, formalize, autoformalize, prove, autoprove, disprove, checkpoint, review, refactor, golf, learn, diagnose) — LSP-first, scripts fallback",
  "author": {"name": "Cameron Freer", "email": "[email protected]"}
}

Contents

What it installs

The manifest is a name and a version. 1 skill, 12 commands, 4 agents, 3 hooks travel with it, and installing the plugin installs all of them — 423 tokens a session between them. Each is measured on its own page, and each can be installed alone.

Changes

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.

19d ago Changed 3171a646d019
21d ago Changed e9fe5b07a5de
26d ago Changed 52a3e18cbb45
27d ago Changed 66b4919454b4
1mo ago Changed 1903fa26ed4d
1mo ago Changed b9487f3b6977
1mo ago Changed 93eaf40bb28d
1mo ago Changed f44a36dc2193
1mo ago Changed 7c342455edb1
1mo ago First seen · 7 lines scan A 47ab8d299906

Subscribe to this mod's changes

lean4 is a plugin published in the GitHub repository cameronfreer/lean4-skills (465 stars, last pushed 19d ago), licensed MIT. Its token cost is not measured: this kind of file is read by the harness, not the model. 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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