-sub set_nntp_headers {
- my ($hdr, $ng, $n, $mid) = @_;
+sub xref ($$$$) {
+ my ($self, $ng, $n, $mid) = @_;
+ my $ret = $self->{nntpd}->{servername} . " $ng->{newsgroup}:$n";
+
+ # num_for is pretty cheap and sometimes we'll lookup the existence
+ # of an article without getting even the OVER info. In other words,
+ # I'm not sure if its worth optimizing by scanning To:/Cc: and
+ # PublicInbox::ExtMsg on the PSGI end is just as expensive
+ foreach my $other (@{$self->{nntpd}->{grouplist}}) {
+ next if $ng eq $other;
+ my $num = eval { $other->mm->num_for($mid) } or next;
+ $ret .= " $other->{newsgroup}:$num";
+ }
+ $ret;
+}
+
+sub set_nntp_headers ($$$$$) {
+ my ($self, $hdr, $ng, $n, $mid) = @_;