[Darkonig]

Well that was fun

since you are changing packages you do need to pass the $client reference to the plugin, but in order to be usable by the plugin it has to be blessed. So:

sub check_hasitem {
 my $client = shift;
 my $itmchk = shift;
 bless($client,"Client");
 
 my $slot1; 
 my $itemid1; 

 #Check main inventory and cursor 
 for($slot1=0; $slot1<=30; $slot1++) {
   $itemid1=$client->GetItemIDAt($slot1); 
   if($itemid1==$itmchk) {
     return 1;
   }
 }
...
}

and then call with

   if(plugin::check_hasitem($client, 1001)) {
      quest::say("Ah i see you have a cloth cap");
   }