>>416266893
also the group must necessarily be open to join and at that point a rando can just join the group from their friend and join anyway.
I hate the concept of having a "code" but it's the best automated way to only allow in people who read the thread.
Both with groups and with a code, you'd also be keeping out people who use 4chan a lot but don't actively read this thread, both with groups and with threads. Remember that this is supposed to be a 4chan community and not just "exclusively people who read this one general every day".