server and web app

apps/server/internal/httpserver/static/realtime.js

@@ -1,4 +1,23 @@
 (function () {
+  const realtimeCallbacks = {
+    notification: [],
+  };
+
+  window.__cairnquireRealtime = {
+    on: function (event, cb) {
+      if (realtimeCallbacks[event]) {
+        realtimeCallbacks[event].push(cb);
+      }
+    },
+    off: function (event, cb) {
+      if (realtimeCallbacks[event]) {
+        realtimeCallbacks[event] = realtimeCallbacks[event].filter(function (c) {
+          return c !== cb;
+        });
+      }
+    },
+  };
+
   const notice = document.querySelector("[data-version-notice]");
   const reload = document.querySelector("[data-version-reload]");
   const offlineNotice = document.querySelector("[data-offline-notice]");
@@ -300,6 +319,13 @@
         return;
       }
 
+      if (payload.type === "notification") {
+        realtimeCallbacks.notification.forEach(function (cb) {
+          cb(payload.data);
+        });
+        return;
+      }
+
       if (payload.type !== "document_version" || !payload.data) {
         return;
       }