mod_rest: Declare presence priority an integer in -128..127 per RFC6121 util.datamapper doesn't actually understand min/max, but it's informative and the schema could be used to validate the input at some point.

module:hook("message/host", function (event)
	local stanza = event.stanza;
	if #stanza.tags == 1 and stanza.tags[1].attr.xmlns == "http://jabber.org/protocol/chatstates" then
		return true;
	end
end, -10);