fix(notifications): don't lose live alerts until a page refresh

The SignalR connection used the default auto-reconnect, which gives up after
~30s and, even when it did reconnect, never re-ran JoinCafe — so the client
dropped out of the café group and silently stopped receiving notifications until
a manual refresh. Now it retries forever (capped backoff), re-joins the group on
reconnect (and catches up via invalidate), and re-establishes the connection when
the network returns or the tab is refocused. As a safety net, the unread/bell and
tab-badge polls now run in background tabs too (refetchIntervalInBackground).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web/dashboard/src/lib/hooks/use-notifications-feed.ts

@@ -40,6 +40,9 @@ export function useNotificationsFeed(options: UseNotificationsFeedOptions = {})
     queryFn: () => fetchNotifications(cafeId!, unreadOnly, limit),
     enabled: !!cafeId,
     refetchInterval: 60_000,
+    // Keep polling even when the tab is in the background, so the unread count
+    // stays current if the live socket missed something — no refresh needed.
+    refetchIntervalInBackground: true,
   });
 
   const refresh = useCallback(() => {

web/dashboard/src/lib/notifications/use-tab-badge.ts

@@ -94,6 +94,7 @@ export function useTabBadge() {
     queryFn: () => fetchNotifications(cafeId!, false, 50),
     enabled: !!cafeId,
     refetchInterval: 60_000,
+    refetchIntervalInBackground: true, // update the tab badge even when unfocused
   });
 
   const unread = data?.unreadCount ?? 0;

web/dashboard/src/lib/realtime/use-order-alerts.ts

@@ -54,10 +54,23 @@ export function useOrderAlerts() {
         accessTokenFactory: () =>
           (typeof window !== "undefined" ? localStorage.getItem("meezi_access_token") : null) ?? "",
       })
-      .withAutomaticReconnect()
+      // Retry FOREVER (capped backoff). The default policy gives up after ~30s,
+      // leaving the connection dead until a page refresh → missed notifications.
+      .withAutomaticReconnect({
+        nextRetryDelayInMilliseconds: (ctx) =>
+          Math.min(30000, 1000 * 2 ** Math.min(ctx.previousRetryCount, 5)),
+      })
       .build();
 
     let stopped = false;
+    const joinCafe = () => connection.invoke("JoinCafe", cafeId).catch(() => {});
+
+    // On reconnect the server group membership is gone — re-join or we silently
+    // stop receiving notifications. Also catch up anything missed while down.
+    connection.onreconnected(() => {
+      void joinCafe();
+      void qc.invalidateQueries({ queryKey: ["notifications", cafeId] });
+    });
 
     const severityFor = (type: string) => {
       if (type === "table_call_waiter") return notify.warning;
@@ -104,14 +117,36 @@ export function useOrderAlerts() {
     void connection
       .start()
       .then(() => {
-        if (!stopped) return connection.invoke("JoinCafe", cafeId);
+        if (!stopped) return joinCafe();
       })
       .catch(() => {
         // connection/auth failed — alerts simply won't fire; no UI breakage
       });
 
+    // If the connection fully dropped (gave up, or the device slept), bring it
+    // back when the network returns or the tab is focused again.
+    const ensureConnected = () => {
+      if (stopped) return;
+      if (connection.state === signalR.HubConnectionState.Disconnected) {
+        void connection
+          .start()
+          .then(() => {
+            if (!stopped) return joinCafe();
+          })
+          .then(() => qc.invalidateQueries({ queryKey: ["notifications", cafeId] }))
+          .catch(() => {});
+      }
+    };
+    const onVisible = () => {
+      if (document.visibilityState === "visible") ensureConnected();
+    };
+    window.addEventListener("online", ensureConnected);
+    document.addEventListener("visibilitychange", onVisible);
+
     return () => {
       stopped = true;
+      window.removeEventListener("online", ensureConnected);
+      document.removeEventListener("visibilitychange", onVisible);
       void connection.stop();
     };
   }, [cafeId, locale, qc]);