/** An unavailable control's props. With a reason it stays focusable (`aria-disabled`, which
 *  `FocusSafeButton` keeps inert to a click, and the reason read out with its name; the caller shows
 *  it in a tooltip — DESIGN.md "Unavailable with a reason stays focusable"); without one it is
 *  plainly off. */
export function unavailable(disabled: boolean | undefined, reason: string | undefined) {
  if (!disabled) return {};
  return reason
    ? { "aria-disabled": true as const, "aria-description": reason }
    : { disabled: true };
}