Separately credentialed Xero App Store subscription and usage-billing operations. Generated from Xero's official OpenAPI repository at immutable commit e952d0bda3628facbf7afc5990ad6a0e7e77bd1e; the exact xero-app-store.yaml bytes are SHA-256 pinned. Xero documents marketplace.billing as a non-tenanted client-credentials scope; this leaf therefore uses a separate manually managed bearer connection and is not installed by the ordinary Xero front door. Reads are uncached; all mutations are grant-off and require approval every run. JSON responses preserve unsafe integer literals as exact strings. No work-entity Source is declared because the official response contracts do not guarantee both a mandatory stable identity and a mandatory version field for an honest task, note, or project projection.