Maybe for now, try?
This would be a replicant of the window you just parted, that way you can check on text you parted before?
on *:JOIN:#:{
if ($nick == $me) { .log $chan -f $+($chan,.doc) }
}
on *:PART:#:{
if ($nick == $me) {
.window -ak0 $+(@,$chan,)
loadbuf $+(@,$chan,) $+($chan,.doc)
}
}