I just hate answering my own question, because I want to see how someone better at this sort of thing might do it. But I also don't want this question to disappear.

This is a simple IGS client ...

#!/usr/bin/perl

use strict;
use Term::ReadLine;
use IO::Socket;
use IO::Select;
use threads;
use threads::shared;

## This is the IGS go server.  Welcome to text mode.
## You must create a username on their website to get this to work
my @pair = (qw(igs.joyjoy.net 6969));

my $cmds   : shared = "";
my $prompt : shared = "igs> ";
my $done   : shared = 0;

my $term     = new Term::ReadLine "igs";
my $listener = new threads( \&listener );

&sender;
$listener->join;

exit;

sub sender {
    while( defined(my $line = $term->readline($prompt)) ) {
        lock $cmds;
        $cmds .= "$line\n";
        return if $done;
    }   
}   

sub listener {
    my $sock = new IO::Socket::INET( PeerAddr => $pair[0], PeerPort =>
+ $pair[1], Proto => "tcp" ) or logger->error("pfft: $!");
    my $sele = new IO::Select;
    
    my $eb_count = 0;
    my $last     = time+60;
    
    $sele->add( $sock );
    
    while( $sock->connected ) {
        if( $sele->can_read(0.1) ) {
            my $buf = undef;
            my $sock_addr = recv( $sock, $buf, 1024, 0 );
            
            if( not defined $sock_addr ) {
                die "socket error";
            }   

            if( not $buf ) {
                #print "empty \$buf...\n";

                if( (++ $eb_count) >= 20 ) {
                    warn "connection terminated\n(return to quit)\n";
                    $done = 1;
                    return;
                }
            }

            our $ayt;
            $ayt -- if $ayt and $buf =~ s/(?:\s*|\b)yes\s*(?=\n)//s;
            $prompt = $1 if $buf =~ s/([^\r\n]+?)$//s;

            if( $buf ) {
                print $buf;
                $term->set_prompt( $prompt );
                $term->forced_update_display;
                $eb_count = 0;
            }

        }

        if( $cmds ) {
            lock $cmds;
            print $sock $cmds;
            $cmds = "";
        }

        if( $last+60 < (my $now = time) ) {
            our $ayt ++;
            print $sock "ayt\n";
            $last = $now;
        }
    }

    shutdown $sock, 2;
}
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