Design-session capture of issue #11 (Cameron adopted 'make them messages'). Money stays on the account graph; its paperwork - invoices, POs, pay stubs, statements, past-due notices - becomes interceptable messages. 'Financial' is a payload type, not a fifth delivery channel (invoice/PO ride Email, statement/notice ride Filing), retiring the overloaded MessageChannel::Financial enum into an accounting-carrier capability - the fusion of issue #11's options 1 and 2. Tap/inject/ redirect become the point: forge an invoice that authorizes a real transfer under a persona; intercept a past-due notice. Discovery is only through the mail; the books and mail stay consistent. Spec now, build later: messages.md (payload + criterion 8) and economy.md (tap/inject) mark it decided-not-yet-runtime; tap_accounting stands until the build lands. Defense: design-session capture - the decision in wiki/log/decisions/2026-07-17.md is written into its two owning specs. No behavior change yet; implementation dispatched.