Standby

It reads charge, runtime, load and mains voltage straight off the battery over the USB cable you already have plugged in. When the power goes and doesn’t come back, it shuts the machine down cleanly while there’s still battery left to do it in — and stands down by itself if the mains returns mid-count. Your UPS already speaks the standard HID power protocol, so there is no vendor driver, no background service, no Java runtime and no account; it reads the device Windows already found and leaves the inbox battery driver exactly where it sits.