A notice the whole hall shows: hall-announce on the host, served by every game's site, shown at the top of each page

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Jm2auWk6RP71CjaAb4FMoG

gamehall/ops/hall-announce.sh

@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+# The notice every game of Kestrel's Hall shows at the top of its pages.
+# Each site serves /var/lib/hall/announcement.json at /hall/announcement.json;
+# a page checks it on load and every few minutes. Run on the host as root:
+#   hall-announce "Kestrel's Hall is down for five minutes of maintenance" --at "2026-09-30 11:00 UTC" [--until "2026-09-30 11:15 UTC"]
+#   hall-announce --show
+#   hall-announce --clear
+# --at is when it happens, told in each reader's own time; --until is when the
+# notice stops showing (an hour after --at when not given).
+set -euo pipefail
+FILE=/var/lib/hall/announcement.json
+
+case "${1:-}" in
+  --clear) rm -f "$FILE"; echo "cleared."; exit 0 ;;
+  --show) cat "$FILE" 2>/dev/null || echo "no announcement."; exit 0 ;;
+  ''|-*) sed -n '2,9p' "$0" | sed 's/^# \{0,1\}//'; exit 2 ;;
+esac
+
+TEXT="$1"; shift
+AT=""; UNTIL=""
+while [ $# -gt 0 ]; do
+  case "$1" in
+    --at) AT="$(date -u -d "$2" +%Y-%m-%dT%H:%M:%SZ)"; shift 2 ;;
+    --until) UNTIL="$(date -u -d "$2" +%Y-%m-%dT%H:%M:%SZ)"; shift 2 ;;
+    *) echo "unknown option: $1" >&2; exit 2 ;;
+  esac
+done
+[ -n "$AT" ] && [ -z "$UNTIL" ] && UNTIL="$(date -u -d "$AT + 1 hour" +%Y-%m-%dT%H:%M:%SZ)"
+
+mkdir -p "$(dirname "$FILE")"
+# A new id each time, so a reader who dismissed the last notice still sees this one.
+TEXT="$TEXT" AT="$AT" UNTIL="$UNTIL" ID="$(date -u +%Y%m%dT%H%M%S)" python3 -c '
+import json, os
+a = {"id": os.environ["ID"], "text": os.environ["TEXT"]}
+if os.environ["AT"]: a["at"] = os.environ["AT"]
+if os.environ["UNTIL"]: a["until"] = os.environ["UNTIL"]
+print(json.dumps(a))' > "$FILE.tmp"
+chmod 644 "$FILE.tmp"
+mv "$FILE.tmp" "$FILE"
+cat "$FILE"