Bring script headers onto the template and close safeguard gaps

Headers claimed protections the code never had, and several destructive paths had no
guard against a collapsed config value.

Orchestrators/intermediate_sync_maintenance.sh

@@ -40,13 +40,36 @@
 # OPERATIONAL SAFEGUARDS
 # ==============================================================================================
 #
-#   Root check           — scripts called here require root
-#   acquire_lock         — prevents concurrent intermediate windows
-#   detect_hosts()       — aliases correct per-host share lists
-#   check_connectivity   — verified before any rsync (skipped if no shares)
-#   check_remote_rootfs  — aborts rsync if remote rootfs nearly full
-#   Non-fatal jobs       — a failed arr_sync warns but does not block rsync or artwork fetch
-#   Minimal on success   — runs 6x/day; full breakdown only on failure or --log
+# Root Enforcement
+#   Every script called from here requires root.
+#
+# Lock Acquisition
+#   acquire_lock prevents concurrent intermediate windows.
+#
+# Host Detection
+#   detect_hosts() aliases the correct per-host share lists.
+#
+# Empty Job List Guard
+#   Exits with an error and a notification if INTERMEDIATE_MAINTENANCE_SCRIPTS is empty,
+#   rather than running six no-op windows a day that all report success.
+#
+# Connectivity Check
+#   check_connectivity is verified before any rsync, and skipped entirely when no shares
+#   are configured — there is nothing to reach a partner for.
+#
+# Remote Rootfs Check
+#   check_remote_rootfs aborts rsync if the remote rootfs is nearly full.
+#
+# Drive Temperature Escalation
+#   rsync.sh's exit code is honoured per share: exit 1 skips that share, exit 2 aborts
+#   every remaining sync in the window and notifies.
+#
+# Non-Fatal Jobs
+#   A failing arr_sync warns but does not block rsync or the artwork fetch that follow it.
+#
+# Minimal on Success
+#   Runs six times a day, so the full breakdown only prints on failure or with --log.
+#   A quiet run is the normal outcome and should not fill the log.
 #
 # ==============================================================================================
 # CONFIGURATION
@@ -101,6 +124,16 @@ fi
 acquire_lock
 
 detect_hosts
+
+# An unconfigured job list would run nothing and still report "0/0 passed" — indistinguishable
+# from a healthy run. Fail loudly instead of silently doing no work.
+if [[ ${#INTERMEDIATE_MAINTENANCE_SCRIPTS[@]} -eq 0 ]]; then
+    error "INTERMEDIATE_MAINTENANCE_SCRIPTS is empty — no intermediate maintenance scripts will run"
+    error "Check INTERMEDIATE_MAINTENANCE_SCRIPTS in master.conf"
+    notify "intermediate maintenance scripts skipped on $(hostname) ($MY_ID) — INTERMEDIATE_MAINTENANCE_SCRIPTS is empty" \
+        "$(basename "$0" .sh)" "warning"
+    exit 1
+fi
 resolve_remote_ip
 
 [[ "$DRY_RUN" == true ]] && warn "DRY RUN — no changes will be made"