diff --git a/cinny/lotus_deploy.sh b/cinny/lotus_deploy.sh
index f7adeeb..4829048 100755
--- a/cinny/lotus_deploy.sh
+++ b/cinny/lotus_deploy.sh
@@ -177,6 +177,50 @@ for dir in assets public/element-call/assets; do
     find "$WEBROOT/$dir" -type f -mtime +14 -delete
 done
 
+# Every script/stylesheet the app and call pages reference must exist in the
+# webroot. 2026-10-20: the call page's index.html pointed at scripts the deploy
+# never copied and calls failed to load; this check would have caught it.
+missing_assets() {  # <index.html> <its directory>
+    grep -oE '(src|href)="[^"]+\.(js|css)"' "$1" | sed -E 's/^(src|href)="//; s/"$//' |
+        while read -r ref; do
+            case "$ref" in
+                http://*|https://*|//*) continue ;;
+                /*) path="$WEBROOT$ref" ;;
+                *) path="$2/${ref#./}" ;;
+            esac
+            [ -f "$path" ] || echo "$ref"
+        done
+}
+deploy_alert() {  # best effort: the upstream checker's Matrix credentials
+    [ -r /etc/cinny-monitor.env ] || return 0
+    (
+        set -a
+        # shellcheck source=/dev/null
+        source /etc/cinny-monitor.env
+        set +a
+        _ALERT="$1" python3 - <<'PYEOF'
+import json, os, time, urllib.parse, urllib.request
+server = os.environ.get("MATRIX_SERVER", "").rstrip("/")
+room, token = os.environ.get("MATRIX_ROOM", ""), os.environ.get("MATRIX_TOKEN", "")
+if server and room and token:
+    url = f"{server}/_matrix/client/v3/rooms/{urllib.parse.quote(room, safe='')}/send/m.room.message/deploy{int(time.time() * 1000)}"
+    req = urllib.request.Request(url, method="PUT", data=json.dumps({"msgtype": "m.text", "body": os.environ["_ALERT"]}).encode(),
+                                 headers={"Authorization": f"Bearer {token}", "Content-Type": "application/json"})
+    try:
+        urllib.request.urlopen(req, timeout=10)
+    except Exception as exc:
+        print(f"alert failed: {exc}")
+PYEOF
+    ) || true
+}
+MISSING=$(missing_assets "$WEBROOT/index.html" "$WEBROOT"; missing_assets "$WEBROOT/public/element-call/index.html" "$WEBROOT/public/element-call")
+if [ -n "$MISSING" ]; then
+    echo "[$(date '+%Y-%m-%d %H:%M:%S')] ERROR: deployed pages reference missing files:"
+    echo "$MISSING"
+    deploy_alert "⚠️ Lotus Chat deploy ($VITE_APP_VERSION): the live pages reference files that are not on the server, so the app or calls may not load: $(echo "$MISSING" | tr '\n' ' ')"
+    exit 1
+fi
+
 echo "[$(date '+%Y-%m-%d %H:%M:%S')] ===== Deploy complete ($VITE_APP_VERSION) ====="
 
 # A trigger arrived while we were deploying: release the lock and run once more