frontend/app/(app)/_layout.tsx

import { useEffect, useState } from 'react';
import { ActivityIndicator, View } from 'react-native';
import { Redirect } from 'expo-router';

import { AppRouteStack } from '../../src/app-navigation/AppRouteStack';
import { messageManager, useAuthStore } from '../../src/stores';
import { useRegisterPushDevice } from '../../src/hooks';
import { hrefAuthLogin } from '../../src/navigation/hrefs';
import { useAppColors } from '../../src/theme';

export default function AppLayout() {
  const isAuthenticated = useAuthStore((s) => s.isAuthenticated);
  const fetchCurrentUser = useAuthStore((s) => s.fetchCurrentUser);
  const userID = useAuthStore((s) => s.currentUser?.id);
  const colors = useAppColors();
  const [verified, setVerified] = useState(false);

  useEffect(() => {
    // 冷启动 token 校验：仅鉴权分组 (app) 需要。
    // 公开页（/privacy、/terms）和 (auth) 分组在根布局直接渲染，不受此校验影响，
    // 因此冷启动 401 不会把公开页顶到 /login。
    fetchCurrentUser().finally(() => setVerified(true));
  }, [fetchCurrentUser]);

  useRegisterPushDevice(isAuthenticated, userID);

  useEffect(() => {
    messageManager.initialize();
  }, []);

  // 持久化状态显示已登录则立即渲染（后台静默校验）
  if (isAuthenticated) {
    return <AppRouteStack />;
  }

  // 未登录且校验未完成，显示 loading
  if (!verified) {
    return (
      <View
        style={{
          flex: 1,
          justifyContent: 'center',
          alignItems: 'center',
          backgroundColor: colors.background.default,
        }}
      >
        <ActivityIndicator size="large" color={colors.primary.main} />
      </View>
    );
  }

  // 校验完成仍未登录，跳转登录页
  return <Redirect href={hrefAuthLogin()} />;
}