ALTER TABLE cases
  ADD COLUMN archived_at DATETIME NULL AFTER created_by_user_id,
  ADD COLUMN archived_by_user_id CHAR(36) NULL AFTER archived_at,
  ADD KEY idx_cases_archived (law_firm_id, archived_at, status_code),
  ADD CONSTRAINT fk_cases_archived_by
    FOREIGN KEY (archived_by_user_id) REFERENCES users (id);
