patbond-flutter/lib/core/navigation/fade_route.dart

import 'package:flutter/material.dart';

/// 统一页面切换：300ms 淡入淡出（12 号组装稿 §7 流程约束）。
Route<T> fadePageRoute<T>(Widget page) {
  return PageRouteBuilder<T>(
    transitionDuration: const Duration(milliseconds: 300),
    reverseTransitionDuration: const Duration(milliseconds: 300),
    pageBuilder: (context, animation, secondaryAnimation) => page,
    transitionsBuilder: (context, animation, secondaryAnimation, child) {
      return FadeTransition(opacity: animation, child: child);
    },
  );
}