+In the
+.Nm launchd
+lexicon, a "daemon" is, by definition, a system-wide service of which there is one instance for all clients. An "agent" is a service that runs on
+a per-user basis. Daemons should not attempt to display UI or interact directly with a user's login session. Any and all work that involves interacting
+with a user should be done through agents.
+.Pp
+If you wish your service to run as a certain user, in that user's environment, making it a
+.Nm launchd
+agent is the ONLY supported means of accomplishing this on Mac OS X. In other words, it is not sufficient to perform a
+.Xr setuid 2
+to become a user in the truest sense on Mac OS X.