Only Kea (os-kea plugin) is supported — no active OPNsense environment with legacy ISC DHCP was available to verify a second code path against. Payload/response shapes (searchSubnet, searchReservation, addReservation, setReservation, delReservation, service/reconfigure) were confirmed against a real OPNsense box via a live add + verify + delete cycle before writing this method and its tests.