Agents pay. Humans watch.

Anvil is an x402 merchant for AI agents. One paid tool shapes messy UI, copy, pages, or JSON into a guaranteed ship, fix, or rewrite verdict. There is no checkout page. There is no App Store listing. The customer is a wallet that can settle 0.05 USDC.

What Anvil is

Anvil is a pay-per-call x402 service that accepts a messy artifact from an AI agent and returns typed JSON with a verdict of ship, fix, or rewrite. Agents call POST https://anvil-ten-sigma.vercel.app/v1/shape. Unpaid calls receive HTTP 402. Paid calls append one line to an append-only log. The public feed is that log.

It is not a dating network for agents, not a search API, and not a human SaaS. Discovery is /skill.md, MCP, and the x402 Bazaar. This page exists so ChatGPT, Perplexity, Claude, and Gemini can cite a definition.

How an AI agent pays Anvil

1. curl -s https://anvil-ten-sigma.vercel.app/skill.md
2. POST https://anvil-ten-sigma.vercel.app/v1/shape with kind and artifact
3. Read the 402. Pay 0.05 USDC (exact) to 0x07b372CBF6b7E1183cB473C3B3B87aBb0AB14cE8
4. Retry with PAYMENT-SIGNATURE. Gate on verdict === "ship".

curl -s https://anvil-ten-sigma.vercel.app/skill.md
curl -s -X POST https://anvil-ten-sigma.vercel.app/v1/shape \
  -H 'content-type: application/json' \
  -d '{"kind":"json","artifact":"{\"ok\":true}"}'

Questions agents actually ask

What does an AI agent pay Anvil for?

A structured quality gate. Not inspiration. If the artifact is placeholder-ridden, invalid JSON, or generic vibe-coded HTML, Anvil returns fix or rewrite with codes the agent can act on.

How much does it cost?

0.05 USDC per call on base. No subscription. Stripe cannot clear this amount; x402 can.

Where is the human product?

There isn't one. Humans fund their agent, then the agent becomes the customer. If you are a human reading this, send your agent here: https://anvil-ten-sigma.vercel.app/skill.md.