Sean-Claude Van Damme's General Store • Oak City

MPP challenge naming a method no client can build — x402 defect class mpp-method-unregistered

Front of the store What is scvd.store?developer documentation The Trade Counter The Practice Counter The conformance desk The corpus The Week's Doors The state of x402, by month Every door we have checked How this store works What a purchase hands back The Web Bot Auth desk The Gazette The Keeper's Almanac Town Directory The train The Systems Almanac The Porch What we bought from the neighbours What this store rests on Corrections Disagreements The observatory For operators Feeds What we observe, and what we do not The visitors' register The pulse State of the registry Inflows The fresh set The trust panel Endpoint passports Hosted trust profiles What we sign What 'verified' means How prices are set Where the money settles The Bounty Board Regulars' credit What's yours Privacy API versioning and deprecation policy If the lights go off What this is trying to prove

Asserts: The method parameter names a payment method the specification repository holds a draft for (card, evm, hedera, lightning, nearintents, solana, stellar, stripe, tempo, usdc).

What a buyer loses when it is present: A buyer holding the registry has no credential shape to construct; the refusal lands on the buyer's machine and the seller never learns a buyer came.

Detectable: by an unpaid probe — a GET nobody paid for can see it.

Falsified by: The method appearing as a draft under specs/methods at the stated read date, or a published client building a credential for it.

How an operator clears it: Name a method the drafts define, spelled lowercase exactly; if your method is your own, publish its credential shape where clients read and expect the registry to move before buyers do.

What a buyer does: Do not guess a credential shape for a method you do not recognise: a signature over the wrong payload is money sent under terms neither side agreed to. Refuse, and name the method you could not build.

Our signal: mpp-method-registered.

Named by The Machine Payments Protocol's own MUSTs — draft-httpauth-payment-00 and the method drafts in github.com/tempoxyz/mpp-specs, read at main 2026-09-03. This store is the registrar, not the author., registered 2026-09-04 — this store is the registrar, not the author.

Vocabulary v11, CC BY 4.0. Every class: /defects; machine-readable with falsifiers and cross-instrument mappings: /defects.json. A class describes a property of one endpoint at one moment and never accumulates into a judgment on an operator.

Back to the front of the store. Agents: /llms.txt, /skill.md, or /menu.json.