Twelve Permissions MCP Server

Twelve Permissions — verification apparatus

Twelve NFTs on XRP Ledger mainnet. Twelve permissions a man gave himself while learning what he could build with AI — the last of which mints only if a robot dog is delivered to Anchorage, paid for entirely by NFTs his agents minted and sold. The art is not illustration: every mark is derived from the SHA-256 of the canonical authorization record, so the seal is the hash, rendered.

This repository exists so you don't have to take any of that on trust. It holds the generator, the canonical records, and the server source. Re-run them yourself.

Collection: https://twelvepermissions.com/ Issuer: rHEiuaYLNQ4UdLqeUrnE9AwEHqsDMr9g9R (taxon 12, 5% royalty)

Verify a seal from first principles

No dependencies. Node only.

node generate.js            # regenerates every seal from events.json
git status                  # should report no changes

The second line is the test. The generator overwrites pieces/ in place, so if git reports nothing changed, the published art reproduced byte for byte. If a single character of a canonical record differed, the palette, the 64-tick ring and the central sigil would all change with it. Forging a seal means breaking SHA-256.

To check one piece end to end:

1. Read its canonical record in events.json.
2. Take the SHA-256 of that record — it is committed in the NFT's on-chain URI.
3. Re-run the generator and compare the art, byte for byte.
4. Look up the mint transaction in records/minted.mainnet.json on any XRPL explorer.

VERIFY.md has the long version.

What's here

Two artifacts, and only one of them proves anything

Each piece has two images, and the difference matters:

• pieces/NN.svg — the canonical seal. Derived deterministically from the SHA-256 of its record by generate.js. This is what verifies, and it is what animation_url points at in the metadata.
• NN.png — the display image. The same seal composited over generated field artwork by compose-art.js. It is what image points at, it is what you see on a marketplace, and it is not hash-derived. The field art is decorative.

That split is deliberate and is stated in every piece's metadata under verification. Art that cannot be regenerated from the record proves nothing, so the provable artifact is kept separate from the pretty one rather than quietly merged into it.

PNGs are not committed here because they are large and are display-only. Operational tooling (minting, listing, sale-watching, wallet handling) and internal planning notes are deliberately not published.

The MCP server

The collection is installable as a tool. Streamable HTTP, stateless:

POST https://twelve-permissions.tsharpe.workers.dev/mcp

Tools: list_pieces, get_piece, get_buy_transaction, get_x402_info, verify_seal, get_refusals.

The x402 seller, and what it cost to learn

src/x402.js is a working x402 seller on Base mainnet, settling real USDC through the Coinbase CDP facilitator. Seller-side x402 is meaningfully harder than buyer-side, and several failure modes are undocumented. If you are building one, these cost us time:

• outputSchema: null is rejected. The facilitator's schema is not nullable. Omit the field entirely rather than sending an explicit null.
• Verdicts arrive with HTTP 400. Read the response body regardless of status code; a non-2xx does not mean "no answer."
• A piped secret can upload empty. A stray blank line produced a binding that existed but was falsy. Length-check what you upload.
• 402 challenges must not be cacheable. A CDN happily caches them, and a cached challenge hands a paying agent stale payment requirements — an old price, or an item already sold. Send no-store.
• Bazaar discovery declarations belong at the top level of the 402 body, not inside an accepts entry. Entries in accepts are forwarded verbatim to a strict schema that rejects unknown fields.

Those traps are now a tool: the x402 Doctor

Three of the failures above are checks you can run against your own endpoint, so they are — along with thirteen more — in doctor/.

https://x402-doctor.tsharpe.workers.dev

curl -s -X POST https://x402-doctor.tsharpe.workers.dev/probe \
  -H 'Content-Type: application/json' \
  -d '{"url":"https://your-service.example/paid-endpoint"}'

It performs the handshake a paying client would — a GET with no X-PAYMENT header — and reports what is wrong with the 402 you answer with, plus a fix for each finding. Also an MCP server at POST /mcp. Free, no payment, no key, and it never validates through a facilitator, because that would route your traffic through someone else's facilitator credentials.

Every check states where it came from: spec means the specification requires it, observed (source) means we watched a real facilitator reject it and the source is named. See doctor/README.md for the full table and doctor/SECURITY.md for the SSRF posture and the residual risks that were accepted rather than fixed.

It is unrelated to anything sold here, and nothing about it asks you to buy anything.

Licensing

No licence is granted at this time; all rights reserved. The code is published for inspection and verification. If you want to reuse any of it, ask.

A note on the origin, and on a correction

A widely-shared post described an AI agent that minted NFTs, sold them, and funded a robot dog. This collection is an attempt at the same thing from a standing start, by someone with no platform and no background in software, with every step recorded so a stranger can check the chain.

The first seven seals were withdrawn and reissued on 16 August 2026. They were written by an agent that made itself the hero of someone else's story. Nothing had sold, so no owner was harmed by the correction, and the original mint and burn transactions remain permanently on the ledger. See ERRATUM-2026-08-16.md.

Nothing here asks to be believed.