Treat a real third-party endpoint as a new trust boundary

When a real third-party endpoint replaces a provisional integration, treat it as a new trust boundary. Model the exact wire contract, remove obsolete authentication and route assumptions, and strip undeclared response fields before data enters application state.

This limits accidental propagation of operational or personal fields but does not replace transport controls, business-identity validation, or live verification. Preview fixtures also do not prove a terminal integration when a later authoritative refresh overwrites seeded fields. Trace every upstream overwrite and use a real upstream identifier for a positive canary; otherwise label the result component-level verification.