feat: isolate live section refresh backoff (#167)

frontend/index.html

@@ -1216,8 +1216,12 @@ textarea { resize: vertical; min-height: 120px; }
   }
 
   function renderLiveSnapshot(snapshot) {
-    const notificationsFresh = Array.isArray(snapshot.notifications);
-    if (notificationsFresh) {
+    const contextFreshness = snapshot.freshness?.sections?.context;
+    const eventsFreshness = snapshot.freshness?.sections?.events;
+    const notificationFreshness = snapshot.freshness?.sections?.notifications;
+    const hasNotifications = Array.isArray(snapshot.notifications);
+    const notificationsFresh = hasNotifications && !notificationFreshness?.stale;
+    if (hasNotifications) {
       if (notificationPagination.page > 1) {
         const byId = new Map(lastNotifications.map(item => [item.id, item]));
         snapshot.notifications.forEach(item => byId.set(item.id, item));
@@ -1238,19 +1242,27 @@ textarea { resize: vertical; min-height: 120px; }
     if (snapshot.context) {
       snapshot.context.notifications = lastNotifications;
       renderContextSnapshot(snapshot.context);
-      if (!notificationsFresh) markNotificationsStale();
+      if (contextFreshness?.stale) markMyWorkStale();
+      else if (!notificationsFresh) markNotificationsStale();
     } else handleContextError(new Error('Context section unavailable'));
-    if (snapshot.events) {
-      paintEventStream(snapshot.events);
+    if (Array.isArray(snapshot.events)) paintEventStream(snapshot.events);
+    if (eventsFreshness?.revalidating) {
+      setEventStreamStatus('Refreshing activity · showing last activity');
+    } else if (eventsFreshness?.stale || eventsFreshness?.degraded) {
+      const retrySeconds = Number(eventsFreshness.retry_in_seconds) || 0;
+      setEventStreamStatus('Activity refresh failed · showing last activity' +
+        (retrySeconds > 0 ? ' · retrying in ' + retrySeconds + 's' : ''));
+    } else if (Array.isArray(snapshot.events)) {
       setEventStreamStatus('Updated ' + fmt(new Date()));
     } else {
       setEventStreamStatus('Update failed · showing last activity');
     }
-    if (snapshot.freshness?.degraded && !snapshot.freshness.revalidating) {
+    // Compatibility fallback for snapshots produced before section metadata.
+    if (!eventsFreshness && snapshot.freshness?.degraded && !snapshot.freshness.revalidating) {
       const retrySeconds = Number(snapshot.freshness.retry_in_seconds) || 0;
       setEventStreamStatus('Refresh failed · showing last known data' +
         (retrySeconds > 0 ? ' · retrying in ' + retrySeconds + 's' : ''));
-    } else if (snapshot.freshness?.revalidating) {
+    } else if (!eventsFreshness && snapshot.freshness?.revalidating) {
       setEventStreamStatus('Refreshing · showing recent snapshot');
     }
   }