I am worried that you are just opening a big can of worm here. Are you
sure that you can keep the chat messages free of special character that
would invalidate the GTP stream? Or there could be a bug in the engine
with the handling of GTP-allowed characters that have never appeared
before, that allows any KGS observer to crash a robot running on KGS.
You may at some point want to allow unicode in user names.
(Ok I won't start about the buffer overflow in the GTP input handling of
my engine that allows a remote exploit via KGS chat :)
I think if you do that, you should at least give a configuration option
to limit the kgs-chat interface to a specified list of KGS usernames.