refactor(ProcessPostUseCase, useCursorPagination, useDifferentialPosts): enhance post merging and loading states

- Introduced new methods for merging posts and comments efficiently, improving performance during data updates.
- Updated loading state management in hooks to include initial loading and loading more states for better user feedback.
- Refactored HomeScreen and PostDetailScreen to utilize the new loading states and merging logic, enhancing user experience during data fetching.
- Improved pagination handling in useCursorPagination and useDifferentialPosts to ensure consistent data management across components.

src/screens/message/ChatScreen.tsx

@@ -77,6 +77,7 @@ export const ChatScreen: React.FC = () => {
   
   // 输入框区域高度（用于定位浮动 mention 面板）
   const [inputWrapperHeight, setInputWrapperHeight] = useState(60);
+  const [showEdgeLoadingIndicator, setShowEdgeLoadingIndicator] = useState(false);
   const isPreloadingRef = useRef(false);
   const lastScrollYRef = useRef(0);
   const isUserDraggingRef = useRef(false);
@@ -203,8 +204,15 @@ export const ChatScreen: React.FC = () => {
     loadMoreHistory,
     handleMessageListContentSizeChange,
     handleReachLatestEdge,
+    setBrowsingHistory,
   } = useChatScreen();
 
+  useEffect(() => {
+    if (!loadingMore && showEdgeLoadingIndicator) {
+      setShowEdgeLoadingIndicator(false);
+    }
+  }, [loadingMore, showEdgeLoadingIndicator]);
+
   useEffect(() => {
     return () => {
       if (preloadCooldownTimerRef.current) {
@@ -231,7 +239,7 @@ export const ChatScreen: React.FC = () => {
     return map;
   }, [messages]);
 
-  const renderMessage = ({ item, index }: { item: any; index: number }) => {
+  const renderMessage = useCallback(({ item, index }: { item: any; index: number }) => {
     // inverted 下 renderItem 的 index 与时间顺序不一致，需回查原始序索引
     const logicalIndex = messageIndexMap.get(String(item.id)) ?? index;
     return (
@@ -255,7 +263,26 @@ export const ChatScreen: React.FC = () => {
         onReply={handleReplyMessage}
       />
     );
-  };
+  }, [
+    messageIndexMap,
+    currentUserId,
+    currentUser,
+    otherUser,
+    isGroupChat,
+    groupMembers,
+    otherUserLastReadSeq,
+    selectedMessageId,
+    messageMap,
+    handleLongPressMessage,
+    handleAvatarPress,
+    handleAvatarLongPress,
+    formatTime,
+    shouldShowTime,
+    handleImagePress,
+    handleReplyMessage,
+  ]);
+
+  const keyExtractor = useCallback((item: any) => String(item.id), []);
 
   // 获取正在输入提示
   const typingHint = getTypingHint();
@@ -269,6 +296,11 @@ export const ChatScreen: React.FC = () => {
       viewportHeight: layoutMeasurement.height,
     };
 
+    // 离开最新消息端后进入“浏览历史”模式，屏蔽自动跟随到底
+    if (contentOffset.y > 120) {
+      setBrowsingHistory(true);
+    }
+
     // 仅用户手势主动回到底部时才解除历史阅读锁（避免加载阶段误解锁）
     const isScrollingTowardLatest = contentOffset.y < lastScrollYRef.current;
     if (
@@ -282,13 +314,19 @@ export const ChatScreen: React.FC = () => {
 
     // inverted 下历史端在“列表尾部”，对应 offset 增大且距离尾部变小
     const distanceToHistoryEdge = contentSize.height - (contentOffset.y + layoutMeasurement.height);
-    const isScrollingTowardHistory = contentOffset.y > lastScrollYRef.current;
     lastScrollYRef.current = contentOffset.y;
 
-    const PRELOAD_HISTORY_THRESHOLD = 120;
+    // 预加载阈值：按屏幕高度动态提前（至少 420），确保边界前开始加载
+    const PRELOAD_HISTORY_THRESHOLD = Math.max(420, layoutMeasurement.height * 1.2);
+    // 仅在真正接近边界时才显示旋转提示
+    const EDGE_LOADING_INDICATOR_THRESHOLD = 60;
+    const shouldShowEdgeIndicator = loadingMore && distanceToHistoryEdge <= EDGE_LOADING_INDICATOR_THRESHOLD;
+    if (shouldShowEdgeIndicator !== showEdgeLoadingIndicator) {
+      setShowEdgeLoadingIndicator(shouldShowEdgeIndicator);
+    }
+
     if (
       distanceToHistoryEdge <= PRELOAD_HISTORY_THRESHOLD &&
-      isScrollingTowardHistory &&
       hasMoreHistory &&
       !loadingMore &&
       !loading &&
@@ -304,7 +342,7 @@ export const ChatScreen: React.FC = () => {
         }, 350);
       });
     }
-  }, [scrollPositionRef, hasMoreHistory, loadingMore, loading, loadMoreHistory, handleReachLatestEdge]);
+  }, [scrollPositionRef, hasMoreHistory, loadingMore, loading, loadMoreHistory, handleReachLatestEdge, showEdgeLoadingIndicator, setBrowsingHistory]);
 
   const handleContentSizeChange = useCallback((contentWidth: number, contentHeight: number) => {
     handleMessageListContentSizeChange(contentWidth, contentHeight);
@@ -338,6 +376,7 @@ export const ChatScreen: React.FC = () => {
         onLayout={e => {
           scrollPositionRef.current.viewportHeight = e.nativeEvent.layout.height;
         }}
+        onTouchEnd={handleDismiss}
       >
         {loading ? (
           <View style={styles.loadingContainer}>
@@ -349,10 +388,15 @@ export const ChatScreen: React.FC = () => {
             inverted
             data={displayMessages}
             renderItem={renderMessage}
-            keyExtractor={(item: any) => String(item.id)}
+            keyExtractor={keyExtractor}
             contentContainerStyle={listContentStyle as any}
             showsVerticalScrollIndicator={false}
             keyboardShouldPersistTaps="handled"
+            initialNumToRender={14}
+            maxToRenderPerBatch={10}
+            updateCellsBatchingPeriod={50}
+            windowSize={9}
+            removeClippedSubviews={Platform.OS !== 'web'}
             onScroll={handleMessageListScroll}
             onScrollBeginDrag={() => {
               isUserDraggingRef.current = true;
@@ -368,7 +412,7 @@ export const ChatScreen: React.FC = () => {
             onContentSizeChange={handleContentSizeChange}
           />
         )}
-        {loadingMore && (
+        {showEdgeLoadingIndicator && (
           <View
             pointerEvents="none"
             style={{