-- Audit-final v2 fix: polymorphic discriminator columns are currently free-text
-- and a typo in service code (e.g. `'clients'` vs `'client'`) inserts silently
-- and the row becomes unreachable through every read path that uses the
-- resolver service. Add CHECK constraints on the two most load-bearing
-- discriminators to surface drift at the DB level.

ALTER TABLE yachts
  ADD CONSTRAINT yachts_current_owner_type_chk
    CHECK (current_owner_type IN ('client', 'company'));

ALTER TABLE invoices
  ADD CONSTRAINT invoices_billing_entity_type_chk
    CHECK (billing_entity_type IN ('client', 'company'));