A control plane being stopped held every agent's stream for the thirty
seconds of a graceful shutdown, so the standby led within four seconds and
had no nodes for thirty. The agent server is now closed, not drained. A
control plane that loses its lease while it lives on lets its agents go,
rather than keeping nodes the new leader cannot reach.
ctl status and the console's Overview say which control plane leads, which
stand by, and whether the floating address is on the leader. The console
adds a control plane (Do → Add a control plane), asking for the machine and
the floating address. server add says when the mirror would refuse the new
control plane.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
