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

A correct payment is answered with a server error — x402 defect class settlement-error

Front of the store What is this?developer documentation The Practice Counter The conformance desk The corpus The Week's Doors 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 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: A valid, sufficient payment is answered with a 2xx and the goods.

What a buyer loses when it is present: Money may move with nothing delivered. The failure is invisible to the free preflight, which never pays.

Detectable: only by a paid probe — a settled payment reveals it.

Falsified by: A correctly-formed payment settling and returning a 2xx at the stated moment.

How an operator clears it: Read your settle-path logs: the failure sits after payment verification, most often a facilitator timeout, an unhandled fulfillment exception, or a dead upstream. Fail BEFORE money moves or deliver after it — never answer a settled payment with a 500.

Our signal: launch_check stage: settle.

As other instruments name it: {"instrument":"Cairn (cairnwake.com)","as":"settlement-server-error","verify":"cairnwake.com/scoreboard.json, read 2026-08-23: a public machine-readable rollup of its published reports","falsified_by":"Their class covering refusals of INVALID payments, which is conformant behaviour and not this defect."}.

Vocabulary v9, 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.