Taskfolk Agent Commerce API
Machine-payable credit purchase for a Taskfolk workspace, published as a separate OpenAPI 3.1 document at https://taskfolk.ai/openapi.json. Four operations (/api/mpp/v1/credits/{small|medium|large|custom}) each carry an x-payment-info block and answer an unauthenticated-for-payment call with HTTP 402 plus a WWW-Authenticate Payment challenge; the retry carries an Authorization: Payment payload and settlement returns an Ed25519-signed Payment-Receipt. The same checkout core is exposed through four protocols — MPP (this spec), ACP (/.well-known/acp.json), UCP (/.well-known/ucp) and x402 — all four declared in the RFC 9727 API catalog. Purchases require an API key carrying the admin scope. No refund, void or cancel operation is published, so a completed purchase is irreversible.