maint_start and maint_abort take an optional unit. With two or more batteries each Batteries card has Start cycle and Stop cycle buttons. One slot per site stays: a start while a battery cycles is refused and names it (no queue). A battery that is switched off, an unknown unit, and a stop on a battery that is not cycling are refused with a plain message. A request with no unit is the old call. The scheduler and the phase machine are unchanged. Co-Authored-By: Claude <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Bdqr7PiaHcBnzPituu2yTC