MarsSeed [1] filed a deletion request for sat-cagou-hg [2]: This is not needed, its base sat-xmpp package has been deleted. "SaT" application has been discontinued in 2017, and has been forked into a new app, Libervia. There are AUR packages for that. So it's safe to delete this defunct library.
[1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/sat-cagou-hg/