-- Phase 3: TV display devices, rooms, called counter, retention purge
ALTER TABLE kiosk_devices ADD COLUMN kind ENUM('kiosk','display') NOT NULL DEFAULT 'kiosk' AFTER tenant_id;
ALTER TABLE departments ADD COLUMN room VARCHAR(40) NULL AFTER token_prefix;
ALTER TABLE registrations
  ADD COLUMN called_counter VARCHAR(40) NULL AFTER called_at,
  ADD COLUMN purged_at DATETIME NULL AFTER created_at,
  ADD KEY ix_reg_called (tenant_id, called_at);