fix notification suspend state lost on page reload (#23989)

<camera>/notifications/suspended arrives as a string over the live connection but as a number in the camera_activity snapshot, and the truthiness guard dropped the numeric 0, so a camera with notifications off rendered as active after a reload. Normalize to a string and derive isSuspended instead of storing it.

docs/docs/integrations/mqtt.md

@@ -292,7 +292,9 @@ Topic with the currently active profile name. Published value is the profile nam
 
 ### `frigate/notifications/set`
 
-Topic to turn notifications on and off. Expected values are `ON` and `OFF`.
+Topic to turn notifications on and off for all cameras. Expected values are `ON` and `OFF`.
+
+Only available when notifications are enabled in the config. Not persisted across Frigate restarts.
 
 ### `frigate/notifications/state`
 
@@ -570,16 +572,20 @@ Topic with current state of the Birdseye mode for a camera. Published values are
 
 ### `frigate/<camera_name>/notifications/set`
 
-Topic to turn notifications on and off. Expected values are `ON` and `OFF`.
+Topic to turn notifications for a camera on and off. Expected values are `ON` and `OFF`.
+
+`ON` is ignored unless notifications are enabled in the config for the camera. This is not persisted across Frigate restarts. It is the same control the UI labels **Suspend until restart**.
 
 ### `frigate/<camera_name>/notifications/state`
 
-Topic with current state of notifications. Published values are `ON` and `OFF`.
+Topic with current state of notifications. Published values are `ON` and `OFF`. This is the authoritative topic for whether a camera will notify.
 
 ### `frigate/<camera_name>/notifications/suspend`
 
-Topic to suspend notifications for a certain number of minutes. Expected value is an integer.
+Topic to suspend notifications for a certain number of minutes. Expected value is an integer. Separate from `notifications/set`: it does not change `notifications/state`, and is ignored while notifications are off.
 
 ### `frigate/<camera_name>/notifications/suspended`
 
-Topic with timestamp that notifications are suspended until. Published value is a UNIX timestamp, or 0 if notifications are not suspended.
+Topic with timestamp that notifications are suspended until. Published value is a UNIX timestamp, or 0 if there is no timed suspension.
+
+`0` does not mean notifications are enabled: `notifications/set` `OFF` clears the timed suspension, so this publishes `0` while `notifications/state` is `OFF`.

web/src/api/ws.ts

@@ -205,7 +205,7 @@ function applyCameraActivity(payload: string) {
     );
     applyTopicUpdate(
       `${name}/notifications/suspended`,
-      notifications_suspended || 0,
+      String(notifications_suspended ?? 0),
     );
     applyTopicUpdate(
       `${name}/ptz_autotracker/state`,
@@ -806,7 +806,7 @@ export function useNotificationSuspend(camera: string): {
     `${camera}/notifications/suspended`,
     `${camera}/notifications/suspend`,
   );
-  return { payload: payload as string, send };
+  return { payload: String(payload ?? 0), send };
 }
 
 export function useNotificationTest(): {

web/src/components/config-form/sectionExtras/NotificationsSettingsExtras.tsx

@@ -746,18 +746,10 @@ export function CameraNotificationSwitch({
     useNotifications(camera);
   const { payload: notificationSuspendUntil, send: sendNotificationSuspend } =
     useNotificationSuspend(camera);
-  const [isSuspended, setIsSuspended] = useState<boolean>(false);
-
-  useEffect(() => {
-    if (notificationSuspendUntil) {
-      setIsSuspended(
-        notificationSuspendUntil !== "0" || notificationState === "OFF",
-      );
-    }
-  }, [notificationSuspendUntil, notificationState]);
+  const isSuspended =
+    notificationSuspendUntil !== "0" || notificationState === "OFF";
 
   const handleSuspend = (duration: string) => {
-    setIsSuspended(true);
     if (duration == "off") {
       sendNotification("OFF");
     } else {

web/src/components/menu/LiveContextMenu.tsx

@@ -228,15 +228,8 @@ export default function LiveContextMenu({
     useNotifications(camera);
   const { payload: notificationSuspendUntil, send: sendNotificationSuspend } =
     useNotificationSuspend(camera);
-  const [isSuspended, setIsSuspended] = useState<boolean>(false);
-
-  useEffect(() => {
-    if (notificationSuspendUntil) {
-      setIsSuspended(
-        notificationSuspendUntil !== "0" || notificationState === "OFF",
-      );
-    }
-  }, [notificationSuspendUntil, notificationState]);
+  const isSuspended =
+    notificationSuspendUntil !== "0" || notificationState === "OFF";
 
   const handleSuspend = (duration: string) => {
     if (duration === "off") {