[Unit]
Description=Detect second DISPLAY using xrandr

[Service]
Type=oneshot
ExecStart=/bin/bash -c '\
    source <(systemctl --user show-environment); \
    SECOND_DISPLAY="$${DISPLAY%\.[0-9]*}.1"; \
    xrandr -d "$SECOND_DISPLAY" -q | grep "connected" && \
        { [ $DISPLAY == $SECOND_DISPLAY ] && echo "DISPLAY=$${DISPLAY%\.[0-9]*}.0 > ~/.second_display || echo "DISPLAY=$SECOND_DISPLAY" > ~/.second_display; \
        } || rm -f ~/.second_display'

[Install]
WantedBy=yavdr-desktop.target