67e6d4ba4d
Two problems made the auto-attach loop: $TMUX was the only nesting guard, and it is trivially lost - sudo -i, env -i, ssh, and dropbear all hand back an interactive tty shell with it unset, so a shell below tmux would start another tmux. The guard also never checked for a login shell, so anything spawning `$SHELL -i` (fzf-tmux, file-manager shell escapes, editor :sh) dragged in a whole tmux client and a fresh grouped session. Now guarded on a login shell with stdin and stdout both a terminal, a $TERM that can host tmux, and an exported $TMUX_AUTOSTART that survives into panes and into nested shells that strip $TMUX. detach-on-destroy was off while the per-client sessions set destroy-unattached on. Those fight: detaching destroys the session, and off means the client is then switched to the most recently active remaining session instead of being allowed to leave - so detach put you back into "main". Restored to on, which is also the default. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>