unix_dgram to NOTIFY_SOCKET failed on rk3528 (embedded Node), so WATCHDOG=1 never
reached systemd despite WATCHDOG_USEC fallback. Switch to exec systemd-notify with
NOTIFY_SOCKET in child env; unit sets NotifyAccess=all so cgroup may notify.
Users must reload unit (re-run install.sh or add NotifyAccess=all manually).
Made-with: Cursor