The command-finished guard required a shell in SHELL_NAMES, so a user on
ksh/dash/tcsh/csh/ash/elvish/xonsh could never settle launched-agent hook
authority until the pty itself exited. Those are bare shells for every
consumer of the predicate, so widening the set is the correct scope.
The settle-generation Map also kept one entry per abnormally-exited SSH pty:
that branch preserves launch authority by design (unverifiable, not exited),
but the counter is bookkeeping for a check that can no longer land.