恢复原滚动逻辑

app/src/main/java/com/aiosman/riderpro/ui/chat/ChatScreen.kt

@@ -109,13 +109,11 @@ fun ChatScreen(userId: String) {
     }
     // 监听滚动状态，触发加载更多
     LaunchedEffect(listState) {
-        snapshotFlow { listState.layoutInfo.visibleItemsInfo.firstOrNull()?.index }
+        snapshotFlow { listState.layoutInfo.visibleItemsInfo.lastOrNull()?.index }
             .collect { index ->
-                if (index != null && index < 10 && !isLoadingMore && viewModel.hasMore) { // 调整阈值为 10
-                    isLoadingMore = true
+                if (index == listState.layoutInfo.totalItemsCount - 1) {
                     coroutineScope.launch {
                         viewModel.onLoadMore(context)
-                        isLoadingMore = false
                     }
                 }
             }