proof-engine-marketplace

Proof Engine

An AI agent skill that creates formal, verifiable proofs of claims. Every fact is either computed by Python code anyone can re-run or backed by a specific source, URL, and exact quote. The LLM never asserts a fact on its own authority.

Uses the open Agent Skills standard. Works with Claude Desktop, Claude Cowork, Claude Code, Codex CLI, Cursor, Windsurf, Manus, ChatGPT, and any other compatible tool.

What It Does

LLMs have two weaknesses that make them unreliable for factual claims: they hallucinate facts and they make reasoning errors. This skill overcomes both by:

• Offloading facts to citations — every empirical claim must have a source, URL, and exact quote
• Offloading reasoning to code — every computation is executable Python, not prose
• Enforcing 7 hardening rules — closing specific failure modes where proof code looks correct but is silently wrong
• Optionally offline-reproducible — embedded page snapshots let proofs run without network access
• Multi-mode verification — live fetch, embedded snapshots, Wayback Machine archive, and PDF support

The skill produces three outputs: a re-runnable proof.py script, a reader-facing proof.md summary with verdict, and a proof_audit.md with full verification details. Verdicts: PROVED, SUPPORTED, DISPROVED, PARTIALLY VERIFIED, UNDETERMINED, or qualified variants with unverified citations.

Installation

Claude.ai (Web)

1. Download proof-engine.zip
2. Click Customize in the sidebar
3. Go to Skills and click +
4. Choose Upload a skill and upload the zip file

Claude Desktop

— or install manually —

1. Click Customize in the sidebar
2. Click Browse Plugins
3. Go to the Personal tab and click +
4. Choose Add marketplace
5. Type yaniv-golan/proof-engine and click Sync

Claude Code (CLI)

From your terminal:

claude plugin marketplace add https://github.com/yaniv-golan/proof-engine
claude plugin install proof-engine@proof-engine-marketplace

Or from within a Claude Code session:

/plugin marketplace add yaniv-golan/proof-engine
/plugin install proof-engine@proof-engine-marketplace

Cursor

1. Open Cursor Settings
2. Paste https://github.com/yaniv-golan/proof-engine into the Search or Paste Link box

Manus

1. Download proof-engine.zip
2. Go to Settings -> Skills
3. Click + Add -> Upload
4. Upload the zip

ChatGPT

Note: ChatGPT Skills are currently in beta, available on Business, Enterprise, Edu, Teachers, and Healthcare plans only. See OpenAI's documentation for the latest on plan availability.

1. Download proof-engine.zip
2. Upload at chatgpt.com/skills

Codex CLI

Use the built-in skill installer:

$skill-installer https://github.com/yaniv-golan/proof-engine

Or install manually:

1. Download proof-engine.zip
2. Extract the proof-engine/ folder to ~/.codex/skills/

Other Tools (Windsurf, etc.)

Download proof-engine.zip and extract the proof-engine/ folder to:

• Project-level: .agents/skills/ in your project root
• User-level: ~/.agents/skills/

Published Proofs