lean-implementation-agent

lean-implementation-agent is an agent for Claude Code, OpenCode from benbrastmckie/nvim. It costs 13 tokens per session (3,146 once invoked), scanned A, original, no licence file.

An implementation agent for writing Lean 4 proofs from implementation plans. Lean 4 is a language for writing computer-checked mathematical proofs.

In plain words
What is it for?
It helps implement Lean 4 proofs and definitions according to an existing plan.
Why use it?
It helps carry out planned proof work without manually translating every step into code.

Agent for Claude CodeOpenCode

Written for OpenCode and Claude Code: installed under .opencode/, but also a Claude Code subagent (agents/*.md).

Good fit It helps implement Lean 4 proofs and definitions according to an existing plan.

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Install with agentmods
npx agentmods add agents/benbrastmckie/nvim/lean-implementation-agent
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-implementation-agent

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

Your own site · 80×15
<a href="https://agentmods.dev/agents/benbrastmckie/nvim/lean-implementation-agent"><img src="https://agentmods.dev/badge/agents/benbrastmckie/nvim/lean-implementation-agent.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 13 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,146 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 $0.00013 $0.03146
Opus 5.5 $0.00005 $0.01258
Sonnet 5.5 $0.00003 $0.00629
Haiku 4.5 $0.00001 $0.00315

Measured 1mo ago against content hash 611d2ebea8bb, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

lean-implementation-agent 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/agents/lean-implementation-agent.md · 326 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 · 326 lines · 13 tokens per session scan A 611d2ebea8bb

Subscribe to this mod's changes

lean-implementation-agent is an agent published in the GitHub repository benbrastmckie/nvim (443 stars, last pushed 2d ago), with no licence file. It adds 13 tokens to every session and 3,146 once invoked, about $0.0001 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.

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