Switching from session A to B unmounted A's TerminalView, whose socket
close the host treated as a transient drop and started the 30s reconnect-
grace countdown — leaving the user in B for >30s killed A's shell, so
switching back respawned a fresh one instead of reattaching.
Add a third control frame {type:'park'} distinct from refresh/crash
drops: the client sends it on unmount when the tab is still open in its
session's state but the active session has moved on; the host marks the
pty as parked and skips the grace countdown. Switching back (open()
cancels the parked state) or explicitly closing the tab (close frame's
scheduleClose clears it) resume the normal lifecycle. Agent terminals
skip park — their lifetime is already indefinite on a bare drop.
多玩幻灵qwq
29b8615bff