simpler check and deps messages

rig/ctrl/cluster.sh

@@ -1,17 +1,7 @@
 #!/usr/bin/env bash
-# Cluster lifecycle, plus what else is running on this machine.
-#
-# `list` and `free` live here rather than in a separate script because a
-# near-identical second name (cluster / clusters) is a trap — you reach for one
-# and get the other. One target, one file, unambiguous subcommands.
-#
-# "Idempotent" here means CONVERGENT, not "exits early if the cluster exists".
-# That distinction matters: an interrupted first run can leave a cluster created
-# but not finished, and returning early on the re-run would strand it there.
-# The create step is conditional; every step after it always runs, and each one
-# is individually idempotent.
-#
+# Cluster lifecycle (convergent, not exit-early), plus what else runs on this machine.
 # Usage: cluster.sh up | down | reset | list | free
+# Notes: docs/notes/cluster.md
 set -euo pipefail
 cd "$(dirname "$0")"