Refactor: Implement debouncing and anti-flashing fixes

src/components/moderation/ModerationQueue.tsx

@@ -121,6 +121,10 @@ export const ModerationQueue = forwardRef<ModerationQueueRef>((props, ref) => {
   const preserveInteraction = getPreserveInteractionState();
   const useRealtimeQueue = getUseRealtimeQueue();
 
+  // Track recently removed items to prevent realtime override of optimistic updates
+  const recentlyRemovedRef = useRef<Set<string>>(new Set());
+  const prevLocksRef = useRef<Map<string, boolean>>(new Map());
+
   // Store admin settings and stable refs to avoid triggering fetchItems recreation
   const refreshStrategyRef = useRef(refreshStrategy);
   const preserveInteractionRef = useRef(preserveInteraction);
@@ -574,7 +578,7 @@ export const ModerationQueue = forwardRef<ModerationQueueRef>((props, ref) => {
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [user, refreshMode, pollInterval, isInitialLoad, useRealtimeQueue]);
 
-  // Real-time subscription for lock status
+  // Real-time subscription for lock status (optimized to prevent unnecessary updates)
   useEffect(() => {
     if (!user) return;
 
@@ -589,24 +593,21 @@ export const ModerationQueue = forwardRef<ModerationQueueRef>((props, ref) => {
         },
         (payload) => {
           const newData = payload.new as any;
+          const isLocked = newData.assigned_to && newData.assigned_to !== user.id && 
+                           newData.locked_until && new Date(newData.locked_until) > new Date();
+          const wasLocked = prevLocksRef.current.get(newData.id) || false;
+          
+          // Only update if lock state actually changed
+          if (isLocked !== wasLocked) {
+            prevLocksRef.current.set(newData.id, isLocked);
             
-          // Track submissions locked by others
-          if (newData.assigned_to && newData.assigned_to !== user.id && newData.locked_until) {
-            const lockExpiry = new Date(newData.locked_until);
-            if (lockExpiry > new Date()) {
-              setLockedSubmissions((prev) => new Set(prev).add(newData.id));
-            } else {
-              setLockedSubmissions((prev) => {
-                const next = new Set(prev);
-                next.delete(newData.id);
-                return next;
-              });
-            }
-          } else {
-            // Lock released
             setLockedSubmissions((prev) => {
               const next = new Set(prev);
-              next.delete(newData.id);
+              if (isLocked) {
+                next.add(newData.id);
+              } else {
+                next.delete(newData.id);
+              }
               return next;
             });
           }
@@ -635,6 +636,11 @@ export const ModerationQueue = forwardRef<ModerationQueueRef>((props, ref) => {
         async (payload) => {
           const newSubmission = payload.new as any;
           
+          // Ignore if recently removed (optimistic update)
+          if (recentlyRemovedRef.current.has(newSubmission.id)) {
+            return;
+          }
+          
           // Only process pending/partially_approved submissions
           if (!['pending', 'partially_approved'].includes(newSubmission.status)) {
             return;
@@ -857,14 +863,22 @@ export const ModerationQueue = forwardRef<ModerationQueueRef>((props, ref) => {
     const shouldRemove = (activeStatusFilter === 'pending' || activeStatusFilter === 'flagged') && 
                         (action === 'approved' || action === 'rejected');
     
-    // Optimistic update
-    if (shouldRemove) {
-      setItems(prev => prev.filter(i => i.id !== item.id));
-    } else {
-      setItems(prev => prev.map(i => 
-        i.id === item.id ? { ...i, status: action } : i
-      ));
-    }
+    // Optimistic UI update - batch with requestAnimationFrame for smoother rendering
+    requestAnimationFrame(() => {
+      if (shouldRemove) {
+        setItems(prev => prev.filter(i => i.id !== item.id));
+        
+        // Mark as recently removed - ignore realtime updates for 3 seconds
+        recentlyRemovedRef.current.add(item.id);
+        setTimeout(() => {
+          recentlyRemovedRef.current.delete(item.id);
+        }, 3000);
+      } else {
+        setItems(prev => prev.map(i => 
+          i.id === item.id ? { ...i, status: action } : i
+        ));
+      }
+    });
     
     // Release lock if this submission is claimed by current user
     if (queue.currentLock?.submissionId === item.id) {
@@ -1431,13 +1445,20 @@ export const ModerationQueue = forwardRef<ModerationQueueRef>((props, ref) => {
     return (
       <div className="space-y-6">
         {items.map((item) => (
-          <Card key={item.id} className={`border-l-4 ${
-            item.status === 'flagged' ? 'border-l-red-500' :
-            item.status === 'approved' ? 'border-l-green-500' :
+          <Card 
+            key={item.id} 
+            className={`border-l-4 transition-opacity duration-200 ${
+              item.status === 'flagged' ? 'border-l-red-500' :
+              item.status === 'approved' ? 'border-l-green-500' :
             item.status === 'rejected' ? 'border-l-red-400' :
             item.status === 'partially_approved' ? 'border-l-yellow-500' :
             'border-l-amber-500'
-          }`}>
+          }`}
+            style={{ 
+              opacity: actionLoading === item.id ? 0.5 : 1,
+              pointerEvents: actionLoading === item.id ? 'none' : 'auto'
+            }}
+          >
             <CardHeader className={isMobile ? "pb-3 p-4" : "pb-4"}>
               <div className={`flex gap-3 ${isMobile ? 'flex-col' : 'items-center justify-between'}`}>
                 <div className="flex items-center gap-2 flex-wrap">

src/hooks/useModerationStats.ts

@@ -34,6 +34,7 @@ export const useModerationStats = (options: UseModerationStatsOptions = {}) => {
   const [isInitialLoad, setIsInitialLoad] = useState(true);
   const [lastUpdated, setLastUpdated] = useState<Date | null>(null);
   const onStatsChangeRef = useRef(onStatsChange);
+  const statsDebounceRef = useRef<NodeJS.Timeout | null>(null);
   
   // Update ref when callback changes
   useEffect(() => {
@@ -93,27 +94,35 @@ export const useModerationStats = (options: UseModerationStatsOptions = {}) => {
     }
   }, [enabled, fetchStats]);
 
+  // Debounced stats fetch to prevent rapid-fire updates
+  const debouncedFetchStats = useCallback(() => {
+    if (statsDebounceRef.current) {
+      clearTimeout(statsDebounceRef.current);
+    }
+    
+    statsDebounceRef.current = setTimeout(() => {
+      fetchStats(true); // Silent refresh
+    }, 500); // 500ms debounce
+  }, [fetchStats]);
+
   // Realtime subscription for instant stat updates
   useEffect(() => {
     if (!enabled || !realtimeEnabled) return;
 
     const channel = supabase
       .channel('moderation-stats-realtime')
-      .on('postgres_changes', { event: '*', schema: 'public', table: 'content_submissions' }, () => {
-        fetchStats(true); // Silent refresh
-      })
-      .on('postgres_changes', { event: '*', schema: 'public', table: 'reports' }, () => {
-        fetchStats(true);
-      })
-      .on('postgres_changes', { event: '*', schema: 'public', table: 'reviews' }, () => {
-        fetchStats(true);
-      })
+      .on('postgres_changes', { event: '*', schema: 'public', table: 'content_submissions' }, debouncedFetchStats)
+      .on('postgres_changes', { event: '*', schema: 'public', table: 'reports' }, debouncedFetchStats)
+      .on('postgres_changes', { event: '*', schema: 'public', table: 'reviews' }, debouncedFetchStats)
       .subscribe();
 
     return () => {
       supabase.removeChannel(channel);
+      if (statsDebounceRef.current) {
+        clearTimeout(statsDebounceRef.current);
+      }
     };
-  }, [enabled, realtimeEnabled, fetchStats]);
+  }, [enabled, realtimeEnabled, debouncedFetchStats]);
 
   // Polling (fallback when realtime is disabled)
   useEffect(() => {