patbond-flutter/lib/core/network/api_envelope.dart

/// 服务端统一响应信封 `{code, message, data}` 的解析结果。
class ApiEnvelope {
  const ApiEnvelope({required this.code, required this.message, this.data});

  final int code;
  final String message;
  final Object? data;

  /// 从响应体解析信封；结构不符（非 JSON 对象 / 无 int code）返回 null。
  static ApiEnvelope? tryParse(Object? body) {
    if (body is! Map) return null;
    final code = body['code'];
    if (code is! int) return null;
    return ApiEnvelope(
      code: code,
      message: body['message'] is String ? body['message'] as String : '',
      data: body['data'],
    );
  }
}