Reservoir Relay

Send two completed rows to each reservoir. Gravity reverses on delivery, pair orientation alternates, and one manual valve can change the schedule. Each droplet settles independently toward the active reservoir. Completing any row delivers it to that active bank, clears it in place, and reverses gravity. A bank can receive extra rows but they do not replace the other bank’s quota. Manual valve reverses once without changing the next pair orientation. Aim changes are free; undo restores all bank counts and the valve. No timer.