I use the trigger.pl script in irssi to react on a visit by a user of our Kiwi IRC webclient. But it doesn't seem to work like it used to with another webclient before.
I use the trigger
/trigger add -joins -channels "#ffki" -masks "*!~ffki-besu*@*" -command "msg #ffki Hallo $N! Please be patient..."
How do I have to modify the trigger mask so it works with Kiwi IRC?
See Install an ircbot that handles greetings of certain users
Freenode assigns a vhost to all clients connecting, so if that's the network you're using, you can use !@gateway/web/cgi-irc/kiwiirc.com/*
Otherwise, you'll have to compare several users connecting to find a common element between them, and create an appropriate mask using the common elements and the mask.