writing-lean-proofs SKILL.md skillA
writing-lean-proofs from trailofbits/skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add trailofbits/skills/writing-lean-proofs@git:20260807.7b9bd5fPins git:20260807.7b9bd5f in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- trailofbits/skills
- Path
plugins/writing-lean-proofs/skills/writing-lean-proofs/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260807.7b9bd5f, committed Aug 7, 2026
- Size
- 15,997 bytes
- Repository stars
- 8,043
- License
- CC-BY-SA-4.0
Writes and reviews structured Lean 4 proofs and designs Lean libraries following Mathlib conventions. Use when proving theorems in Lean, formalizing mathematics or specifications in Lean 4, defining new types or definitions in a Lean library, reviewing Lean proofs for readability and maintainability, refactoring long tactic proofs into lemmas, filling in sorry placeholders in a Lean development, setting up CI or linters for a Lean project, diagnosing slow proofs or maxHeartbeats timeouts, or…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Writing Lean Proofs ## Contents - [When to Use](#when-to-use) - [When NOT to Use](#when-not-to-use) - [The workflow](#the-workflow) - [The extraction ladder](#the-extraction-ladder) - [Quick reference](#quick-reference) - [Rationalizations to reject](#rationalizations-to-reject) - [References](#references) Structured Lean 4 proof writing and library design, distilled from Mathlib's style and review conventions and from the methodology of large formalization projects (Liquid Tensor Experiment, PFR, Fermat's Last Theorem). **Core principle: design top-down, prove bottom-up.** Lean propositions are proof-irrelevant — only a theorem's *statement* can affect later declarations. Statements are the stable interface; proofs are disposable and freely replaceable. Put design effort into definitions and statements, then fill in proofs against skeletons that already compile (modulo `sorry`). ## When to Use - Proving theorems in Lean 4, from single lemmas to multi-file developments - Formalizing mathematics, protocols, or software specifications in Lean - Defining new types, structures, or functions in a Lean library …
Read the whole file at its exact version.
How to install
mdr add trailofbits/skills/writing-lean-proofs@sha256:fb2ad9c463ac5185The line at the top of this page pins the label git:20260807.7b9bd5f, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_ntje6x5a57pcg2oi)
3 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 1 version of this file, committed on Aug 7, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (15997 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
trailofbits/skills · 8,043 stars · license CC-BY-SA-4.0 · pushed 2026-11-06 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_ntje6x5a57pcg2oi GET https://markdownregistry.com/api/v1/resolve?ref=trailofbits/skills/writing-lean-proofs GET https://markdownregistry.com/api/v1/blob/fb2ad9c463ac5185a014892ce33202460b3423d64405024b95b534f0d3b4d3e0
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.
More from trailofbits/skills
Every file in trailofbits/skills