lean

lean is a command for Claude Code, OpenCode from benbrastmckie/nvim. It costs 8 tokens per session (2,061 once invoked), scanned A, original, no licence file.

A command for managing Lean toolchain and Mathlib versions. Lean is a programming language for writing computer-checked mathematical proofs, and Mathlib is its mathematics library.

In plain words
What is it for?
It helps select and manage the Lean and Mathlib versions used by a project.
Why use it?
It helps keep the compiler and mathematics library versions aligned.

Command for Claude CodeOpenCode

Written for Claude Code and OpenCode: allowed-tools in frontmatter, but also installed under .opencode/.

Good fit It helps select and manage the Lean and Mathlib versions used by a project.

Compare 6 commands from other repositories ↓
Install with agentmods
npx agentmods add commands/benbrastmckie/nvim/lean
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/benbrastmckie/nvim

Made for: Claude Code, OpenCode.

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.

agentmods badge for lean

README.md
[![agentmods](https://agentmods.dev/badge/commands/benbrastmckie/nvim/lean/github.svg)](https://agentmods.dev/commands/benbrastmckie/nvim/lean)
Your own site
<a href="https://agentmods.dev/commands/benbrastmckie/nvim/lean"><img src="https://agentmods.dev/badge/commands/benbrastmckie/nvim/lean/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.

agentmods 80×15 button for lean

Your own site · 80×15
<a href="https://agentmods.dev/commands/benbrastmckie/nvim/lean"><img src="https://agentmods.dev/badge/commands/benbrastmckie/nvim/lean.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 8 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,061 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00008 $0.02061
Opus 5.5 $0.00003 $0.00824
Sonnet 5.5 $0.00002 $0.00412
Haiku 4.5 $0.00001 $0.00206

Measured 1mo ago against content hash c74a0b1aa701, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

lean 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 1mo 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.

.opencode/extensions/lean/commands/lean.md · 354 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

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.

  1. 1mo ago First seen · 354 lines · 8 tokens per session scan A c74a0b1aa701

Subscribe to this mod's changes

lean is a command published in the GitHub repository benbrastmckie/nvim (443 stars, last pushed 2d ago), with no licence file. It adds 8 tokens to every session and 2,061 once invoked, about $0.0000 per session on Opus 5.5. 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 2026-09-03.