systemd-xdg-autostart-generator - User unit generator for XDG autostart files
/usr/lib/systemd/user-generators/systemd-xdg-autostart-generator
systemd-xdg-autostart-generator is a generator that creates .service units for XDG autostart[1] files. This permits desktop environments to delegate startup of these applications to systemd(1) .
Units created by systemd-xdg-autostart-generator can be started by the desktop environment using "xdg-desktop-autostart.target". See systemd.special(7) for more details.
systemd-xdg-autostart-generator implements systemd.generator(7).
systemd(1), systemd.service(5), systemd.target(5)
XDG autostart
https://specifications.freedesktop.org/autostart-spec/autostart-spec-latest.html