diff --git a/packages/ui/src/components/layout/ContextPanel.tsx b/packages/ui/src/components/layout/ContextPanel.tsx
index d45f993d..7e9bbee8 100644
--- a/packages/ui/src/components/layout/ContextPanel.tsx
+++ b/packages/ui/src/components/layout/ContextPanel.tsx
@@ -17,6 +17,8 @@ import { useUIStore, type ContextPanelMode } from '@/stores/useUIStore';
 import { useInlineCommentDraftStore } from '@/stores/useInlineCommentDraftStore';
 import { useSessionUIStore } from '@/sync/session-ui-store';
 import { useInputStore } from '@/sync/input-store';
+import { markSessionViewed } from '@/sync/notification-store';
+import { setExternallyViewedSession } from '@/sync/sync-context';
 import { ContextPanelContent } from './ContextSidebarTab';
 import { toast } from '@/components/ui';
 import { runtimeFetch } from '@/lib/runtime-fetch';
@@ -2176,6 +2178,35 @@ export const ContextPanel: React.FC = () => {
   }, [activeTab, directoryKey, setSelectedFilePath]);
 
   const activeChatTabID = activeTab?.mode === 'chat' ? activeTab.id : null;
+  const activeChatSessionID = activeTab?.mode === 'chat' ? getSessionIDFromDedupeKey(activeTab.dedupeKey) : null;
+
+  React.useEffect(() => {
+    if (!isOpen || !directoryKey || !activeChatSessionID || typeof window === 'undefined') {
+      return;
+    }
+
+    const markActiveChatViewed = () => {
+      if (document.visibilityState === 'hidden' || !document.hasFocus()) {
+        setExternallyViewedSession(directoryKey, activeChatSessionID, false);
+        return;
+      }
+
+      markSessionViewed(activeChatSessionID);
+      setExternallyViewedSession(directoryKey, activeChatSessionID, true);
+    };
+
+    markActiveChatViewed();
+    const interval = window.setInterval(markActiveChatViewed, 10_000);
+    window.addEventListener('focus', markActiveChatViewed);
+    document.addEventListener('visibilitychange', markActiveChatViewed);
+
+    return () => {
+      window.clearInterval(interval);
+      window.removeEventListener('focus', markActiveChatViewed);
+      document.removeEventListener('visibilitychange', markActiveChatViewed);
+      setExternallyViewedSession(directoryKey, activeChatSessionID, false);
+    };
+  }, [activeChatSessionID, directoryKey, isOpen]);
 
   const getEmbeddedChatSrc = React.useCallback((tabID: string, sessionID: string, readOnly: boolean): string => {
     return getOrCreateEmbeddedSessionChatURL(chatFrameSrcByTabIDRef.current, tabID, sessionID, directoryKey || null, readOnly, {