feat: 主页账号备份，并修好 B50 预览缩不小

账号备份（AccountBackupCard + AccountBackupService）：
- 并发读 GetUserData/Extend/Option/Rating/Charge/Activity/MissionData +
  Character + Map（分页）+ KaleidxScope + 各 itemKind 的 GetUserItemApi，
  汇成一个 JSON 字符串可复制到剪贴板。舞里程与总游玩数据本就在
  userData 的 point/totalPoint/playCount 里。
- itemKind 15（KaleidxScopeKey）不列进回读清单：客户端 ExportUserItems
  从不输出它，下行也没有读它的路径，钥匙实际是
  userKaleidxScopeList[].isKeyFound。
- 全程只发 GetUser*Api，不碰 UpsertUserAllApi。
- 逐段容错：私服没实现某个接口时其余照样备出，失败段单独列出——
  「读到但是空的」和「没读到」在 userItemList 里按 kind 分开存，可区分。
- 取数与拼装分开，buildBackupDocument/encode 部分是纯函数，单测覆盖。

B50 预览：原因是 InteractiveViewer(constrained:false) 给孩子无界约束，
FittedBox(fit: fitWidth) 在无界下根本不缩放，海报按 1762x1850 原尺寸铺开；
而 minScale 又算成 1.0，于是既巨大又缩不动。改为给一个 contain 尺寸的
有限盒子让 FittedBox 真正缩放，minScale 固定 1.0（这个版本没有
initialScale 可用）。RepaintBoundary 留在 FittedBox 内侧，绘制尺寸仍是
1762x1850，导出分辨率不受影响，并加了断言守住这点。

README.md

@@ -12,12 +12,13 @@ Android / iOS / Windows / macOS / Linux。
 
 | 入口 | 说明 |
 | --- | --- |
-| 主页 | Aime 登录（QR / 令牌）、Rating 详情、入坑信息、游玩统计、状态 |
+| 主页 | Aime 登录（QR / 令牌）、Rating 详情、入坑信息、游玩统计、状态、账号备份 |
 | 票据 | 功能票查询与使用 |
 | B50 | Best 50 成绩图，可导出 PNG（移植自 Empurple 的 `Best50ImageRenderer`） |
 | 风险 | 歌曲解锁、收藏品获取、旅行伙伴发放与编组（含等级）、修改总 Rating、添加舞里程、一键跑图、万花筒专区 |
 | 设置 | Title Server / Auth Server / 机器参数，支持配置导入导出 |
 | 连接信息（实验性） | 主页导出 uid + JSESSIONID + token 的 Base64 快照，登录页粘贴即可恢复会话；内容未加密，请勿外传 |
+| 账号备份 | 主页只读地把服务器上的用户数据汇成一串 JSON（道具、舞里程、游玩统计、旅行伙伴、区域与万花筒进度、Rating/成绩）。全程只发 `GetUser*Api`，不写任何数据；单段读失败不整体作废，失败段列在结果里 |
 
 ## 开发
 

lib/config/strings.dart

@@ -37,6 +37,23 @@ class AppStrings {
   static const connectionShareEmpty = '当前会话既没有 Cookie 也没有令牌，无法导出。';
   static const restoreSession = '恢复会话';
   static const restoringSession = '恢复中...';
+
+  // 账号备份：把服务器可读到的用户数据汇成一个 JSON 字符串
+  static const accountBackupTitle = '账号备份';
+  static const accountBackupDesc =
+      '只读地把服务器上的用户数据汇成一串 JSON：道具清单、舞里程、游玩统计、'
+      '旅行伙伴、区域进度、万花筒进度、Rating 与成绩等。全程只发 GetUser* 接口，'
+      '不会写任何数据。';
+  static const accountBackupRun = '生成备份';
+  static String accountBackupRunning(String section) =>
+      section.isEmpty ? '备份中...' : '备份中：$section';
+  static const accountBackupCopy = '复制到剪贴板';
+  static const accountBackupCopied = '备份内容已复制到剪贴板';
+  static String accountBackupSize(String size) => '共 $size';
+  static String accountBackupPartial(List<String> failures) =>
+      '${failures.length} 段没读到（私服可能未实现该接口），其余照常：'
+      '${failures.join('、')}';
+  static const accountBackupSecurity = '备份含账号标识与进度数据；内容未加密，请勿贴到公开场合。';
   static const sessionShareDetected = '已识别为连接信息（实验性功能），点击「恢复会话」直接续上这次登录。';
   static const sessionRestoreFailed = '会话恢复失败';
   static const sessionRestoreCookie =

lib/pages/best50_page.dart

@@ -232,22 +232,31 @@ class _Best50PageState extends State<Best50Page> {
           Expanded(
             child: LayoutBuilder(
               builder: (context, constraints) {
-                // 按视口宽度适配：横屏/桌面下海报占满宽度、竖向拖动看全图，
+                // 海报要按视口整体缩放一档，进来才能看见完整一张（之前的现象是
-                // 而不是被 contain 缩成中间一小块、两侧大片空白。
+                // 「太大且缩不小」）。两处坑：
-                // minScale 再允许缩到整张可见，导出仍是原始 1762x1850。
+                //  1. InteractiveViewer(constrained:false) 给子节点无界约束，
+                //     此时 FittedBox 根本不会缩放，必须先给一个有限大小的盒子。
+                //  2. InteractiveViewer 没有 initialScale，所以「初始就缩到位」
+                //     只能靠把子节点做成 contain 尺寸、minScale 固定 1.0。
+                // RepaintBoundary 放在 FittedBox 内侧：它自身的绘制尺寸仍是
+                // 1762x1850，导出分辨率不受这里缩放影响。
                 final fitWidth =
                     constraints.maxWidth / Best50Poster.canvasWidth;
-                final scaledHeight = Best50Poster.canvasHeight * fitWidth;
+                final fitHeight =
-                final containScale = constraints.maxHeight / scaledHeight;
+                    constraints.maxHeight / Best50Poster.canvasHeight;
-                final minScale = containScale < 1 ? containScale : 1.0;
+                final contain = fitWidth < fitHeight ? fitWidth : fitHeight;
 
-                return InteractiveViewer(
+                return Center(
+                  child: InteractiveViewer(
                     constrained: false,
-                  minScale: minScale,
+                    minScale: 1.0,
-                  maxScale: minScale * 6,
+                    maxScale: 10.0,
                     boundaryMargin: const EdgeInsets.all(24),
+                    child: SizedBox(
+                      width: Best50Poster.canvasWidth * contain,
+                      height: Best50Poster.canvasHeight * contain,
                       child: FittedBox(
-                    fit: BoxFit.fitWidth,
+                        fit: BoxFit.fill,
                         child: RepaintBoundary(
                           key: _posterKey,
                           child: Best50Poster(
@@ -259,6 +268,8 @@ class _Best50PageState extends State<Best50Page> {
                           ),
                         ),
                       ),
+                    ),
+                  ),
                 );
               },
             ),

lib/pages/home_page.dart

@@ -10,6 +10,7 @@ import '../models/session_model.dart';
 import '../models/user_data.dart';
 import '../models/user_preview.dart';
 import '../services/title_api_service.dart';
+import '../widgets/account_backup_card.dart';
 import '../widgets/app_notice.dart';
 import '../widgets/connection_share_card.dart';
 import 'about_page.dart';
@@ -539,6 +540,8 @@ class _HomePageState extends State<HomePage> {
             ),
             const SizedBox(height: 12),
             ConnectionShareCard(userId: widget.userId, token: widget.token),
+            const SizedBox(height: 12),
+            AccountBackupCard(userId: widget.userId, cookies: _session.cookies),
             if (TitleApiService.lastRawResponse != null) ...[
               const SizedBox(height: 12),
               _DebugRawJsonCard(

lib/services/account_backup_service.dart

@@ -0,0 +1,117 @@
+import 'dart:convert';
+
+import 'title_api_service.dart';
+
+/// 一次账号备份的结果。
+class AccountBackup {
+  static const int formatVersion = 1;
+
+  final Map<String, dynamic> document;
+
+  /// 读失败的段名（含原因）。备份不因为单段失败而整体作废——
+  /// 私服不一定实现了所有 GetUser* 接口。
+  final List<String> failedSections;
+
+  const AccountBackup({required this.document, required this.failedSections});
+
+  /// 备份正文就是这一长串 JSON。
+  String encode() => const JsonEncoder.withIndent('  ').convert(document);
+
+  int get byteLength => utf8.encode(encode()).length;
+
+  bool get isComplete => failedSections.isEmpty;
+}
+
+/// 把已经读到的各段数据拼成备份文档。与取数分开，方便单测。
+Map<String, dynamic> buildBackupDocument({
+  required int userId,
+  required Map<String, Object?> sections,
+  DateTime? exportedAt,
+}) {
+  return {
+    'backupFormat': AccountBackup.formatVersion,
+    'exportedAt': (exportedAt ?? DateTime.now()).toUtc().toIso8601String(),
+    'userId': userId,
+    'data': sections,
+  };
+}
+
+/// 备份要读的道具类别，对应 `Net.VO.Mai2.ItemKind`。
+///
+/// 只列客户端下行真会读的那些：`StateUserDownload.cs:49-52` 逐个 kind 拉
+/// `GetUserItemApi`，而 itemKind 15（KaleidxScopeKey）客户端从不读
+/// （钥匙是 `userKaleidxScopeList[].isKeyFound`），所以不在此列。
+const List<int> kBackupItemKinds = [1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12];
+
+/// 读取用户数据并汇总成备份。
+///
+/// 每段独立容错：某私服没实现某个接口时，其余部分照样能备出来，
+/// 失败原因记在 [AccountBackup.failedSections] 里给界面显示。
+class AccountBackupService {
+  final TitleApiService _api;
+  final int userId;
+
+  const AccountBackupService(this._api, {required this.userId});
+
+  /// [onSection] 每开始读一段回调一次，供界面显示进度。
+  Future<AccountBackup> run({void Function(String section)? onSection}) async {
+    final sections = <String, Object?>{};
+    final failed = <String>[];
+
+    Future<void> gather(String name, Future<Object?> Function() read) async {
+      onSection?.call(name);
+      try {
+        final value = await read();
+        sections[name] = value;
+      } catch (e) {
+        failed.add('$name: $e');
+      }
+    }
+
+    // 单段一个请求：并发跑，且一段失败不牵连其他段。
+    await Future.wait([
+      gather('userData', () => _api.getUserData(userId)),
+      gather('userExtend', () => _api.getUserExtend(userId)),
+      gather('userOption', () => _api.getUserOption(userId)),
+      gather('userRating', () => _api.getUserRating(userId)),
+      gather('userCharge', () => _api.getUserCharge(userId)),
+      gather('userActivity', () => _api.getUserActivity(userId)),
+      gather('userMissionData', () => _api.getUserMissionData(userId)),
+      gather(
+        'userCharacterList',
+        () async => [
+          for (final c in await _api.getUserCharacters(userId)) c.toWireJson(),
+        ],
+      ),
+      gather('userMapList', () => _api.getUserMaps(userId)),
+      gather(
+        'userKaleidxScopeList',
+        () async => [
+          for (final s in await _api.getUserKaleidxScopes(userId))
+            s.toWireJson(),
+        ],
+      ),
+    ]);
+
+    // userItemList 是按 itemKind 分页拉的，按 kind 分组存放，
+    // 读回时一眼能看出哪类是空的、哪类根本没读到。
+    final items = <String, Object?>{};
+    await Future.wait([
+      for (final kind in kBackupItemKinds)
+        () async {
+          onSection?.call('itemKind $kind');
+          try {
+            items['$kind'] = await _api.getUserItems(userId, kind);
+          } catch (e) {
+            failed.add('userItemList/$kind: $e');
+          }
+        }(),
+    ]);
+    sections['userItemList'] = items;
+
+    return AccountBackup(
+      document: buildBackupDocument(userId: userId, sections: sections),
+      failedSections: failed,
+    );
+  }
+}

lib/widgets/account_backup_card.dart

@@ -0,0 +1,184 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart' show Clipboard, ClipboardData;
+
+import '../config/strings.dart';
+import '../services/account_backup_service.dart';
+import '../services/title_api_service.dart';
+import 'app_card.dart';
+import 'app_notice.dart';
+
+/// 账号备份：把服务器能读到的用户数据汇成一长串 JSON，可复制到剪贴板。
+///
+/// 只读不写——全程只发 `GetUser*Api`，不会碰 UpsertUserAllApi，所以和
+/// 「风险」页那些伪造包相比是安全操作。
+class AccountBackupCard extends StatefulWidget {
+  final int userId;
+  final String? cookies;
+
+  const AccountBackupCard({super.key, required this.userId, this.cookies});
+
+  @override
+  State<AccountBackupCard> createState() => _AccountBackupCardState();
+}
+
+class _AccountBackupCardState extends State<AccountBackupCard> {
+  bool _running = false;
+  String _progress = '';
+  AccountBackup? _result;
+  String? _error;
+
+  Future<void> _run() async {
+    final service = TitleApiService.fromHolder(cookies: widget.cookies);
+    if (service == null) {
+      context.showSnack(AppStrings.ticketNotConfigured);
+      return;
+    }
+
+    setState(() {
+      _running = true;
+      _error = null;
+      _result = null;
+      _progress = '';
+    });
+
+    try {
+      final backup = await AccountBackupService(service, userId: widget.userId)
+          .run(
+            onSection: (section) {
+              if (mounted) setState(() => _progress = section);
+            },
+          );
+      if (!mounted) return;
+      setState(() {
+        _result = backup;
+        _running = false;
+      });
+    } catch (e) {
+      if (!mounted) return;
+      setState(() {
+        _error = '$e';
+        _running = false;
+      });
+    }
+  }
+
+  Future<void> _copy(String text) async {
+    await Clipboard.setData(ClipboardData(text: text));
+    if (!mounted) return;
+    context.showSnack(AppStrings.accountBackupCopied);
+  }
+
+  String _sizeLabel(int bytes) {
+    if (bytes < 1024) return '$bytes B';
+    if (bytes < 1024 * 1024) return '${(bytes / 1024).toStringAsFixed(1)} KB';
+    return '${(bytes / 1024 / 1024).toStringAsFixed(2)} MB';
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final result = _result;
+
+    return AppCard(
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          SectionTitle(
+            icon: Icons.folder_zip_outlined,
+            title: AppStrings.accountBackupTitle,
+          ),
+          const SizedBox(height: 10),
+          Text(
+            AppStrings.accountBackupDesc,
+            style: theme.textTheme.bodySmall?.copyWith(
+              color: theme.colorScheme.onSurfaceVariant,
+            ),
+          ),
+          const SizedBox(height: 14),
+          SizedBox(
+            width: double.infinity,
+            child: FilledButton.tonalIcon(
+              onPressed: _running ? null : _run,
+              icon: _running
+                  ? const SizedBox(
+                      width: 18,
+                      height: 18,
+                      child: CircularProgressIndicator(strokeWidth: 2),
+                    )
+                  : const Icon(Icons.download_outlined, size: 20),
+              label: Text(
+                _running
+                    ? AppStrings.accountBackupRunning(_progress)
+                    : AppStrings.accountBackupRun,
+              ),
+              style: FilledButton.styleFrom(
+                padding: const EdgeInsets.symmetric(vertical: 13),
+                shape: RoundedRectangleBorder(
+                  borderRadius: BorderRadius.circular(12),
+                ),
+              ),
+            ),
+          ),
+          if (_error != null) ...[
+            const SizedBox(height: 12),
+            AppNotice(_error!, icon: Icons.error_outline, error: true),
+          ],
+          if (result != null) ...[
+            const SizedBox(height: 12),
+            if (!result.isComplete) ...[
+              AppNotice(
+                AppStrings.accountBackupPartial(result.failedSections),
+                icon: Icons.warning_amber_rounded,
+              ),
+              const SizedBox(height: 10),
+            ],
+            Row(
+              children: [
+                Expanded(
+                  child: Text(
+                    AppStrings.accountBackupSize(_sizeLabel(result.byteLength)),
+                    style: theme.textTheme.labelSmall?.copyWith(
+                      color: theme.colorScheme.onSurfaceVariant,
+                    ),
+                  ),
+                ),
+                TextButton.icon(
+                  onPressed: () => _copy(result.encode()),
+                  icon: const Icon(Icons.copy_all, size: 18),
+                  label: const Text(AppStrings.accountBackupCopy),
+                ),
+              ],
+            ),
+            Container(
+              width: double.infinity,
+              constraints: const BoxConstraints(maxHeight: 260),
+              padding: const EdgeInsets.all(12),
+              decoration: BoxDecoration(
+                color: theme.colorScheme.surfaceContainerHighest.withValues(
+                  alpha: 0.5,
+                ),
+                borderRadius: BorderRadius.circular(8),
+              ),
+              child: SingleChildScrollView(
+                child: SelectableText(
+                  result.encode(),
+                  style: theme.textTheme.bodySmall?.copyWith(
+                    fontFamily: 'monospace',
+                    fontSize: 11,
+                  ),
+                ),
+              ),
+            ),
+            const SizedBox(height: 10),
+            Text(
+              AppStrings.accountBackupSecurity,
+              style: theme.textTheme.bodySmall?.copyWith(
+                color: theme.colorScheme.error,
+              ),
+            ),
+          ],
+        ],
+      ),
+    );
+  }
+}

test/account_backup_test.dart

@@ -0,0 +1,93 @@
+import 'dart:convert';
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:ichino/services/account_backup_service.dart';
+
+void main() {
+  group('账号备份文档', () {
+    final sections = <String, Object?>{
+      'userData': {
+        'userData': {'point': 123456, 'totalPoint': 999999, 'playCount': 1234},
+      },
+      'userCharacterList': [
+        {'characterId': 101, 'level': 999999, 'awakening': 0, 'useCount': 7},
+      ],
+      'userMapList': [
+        {'mapId': 550002, 'distance': 999999999, 'isComplete': true},
+      ],
+      'userItemList': {
+        '5': [
+          {'itemKind': 5, 'itemId': 11820, 'stock': 1, 'isValid': true},
+        ],
+        '6': const <Object?>[],
+      },
+    };
+
+    test('带格式版本、userId 与 exportedAt，各段挂在 data 下', () {
+      final doc = buildBackupDocument(
+        userId: 42,
+        sections: sections,
+        exportedAt: DateTime.utc(2026, 10, 2, 3, 4, 5),
+      );
+
+      expect(doc['backupFormat'], AccountBackup.formatVersion);
+      expect(doc['userId'], 42);
+      expect(doc['exportedAt'], '2026-10-02T03:04:05.000Z');
+      expect(doc['data'], sections);
+    });
+
+    test('encode 出来的是能原样解回来的 JSON 字符串', () {
+      final backup = AccountBackup(
+        document: buildBackupDocument(userId: 42, sections: sections),
+        failedSections: const [],
+      );
+
+      final text = backup.encode();
+      expect(text, isA<String>());
+      expect(text.contains('11820'), isTrue);
+
+      final back = jsonDecode(text) as Map<String, dynamic>;
+      final data = back['data'] as Map<String, dynamic>;
+      final userData =
+          (data['userData'] as Map<String, dynamic>)['userData']
+              as Map<String, dynamic>;
+      expect(userData['point'], 123456);
+
+      final items = data['userItemList'] as Map<String, dynamic>;
+      expect(items['5'], hasLength(1));
+      // 空的那一类要留着：「读到但是空的」和「没读到」不是一回事。
+      expect(items.containsKey('6'), isTrue);
+      expect(items['6'], isEmpty);
+    });
+
+    test('单段失败不算整体失败，但会记下来并让 isComplete 变 false', () {
+      final backup = AccountBackup(
+        document: buildBackupDocument(userId: 7, sections: sections),
+        failedSections: const ['userMaps: HTTP 500', 'userItemList/12: 超时'],
+      );
+
+      expect(backup.isComplete, isFalse);
+      expect(backup.failedSections, hasLength(2));
+      // 失败信息不进 data，备份正文仍然可用。
+      expect(
+        (jsonDecode(backup.encode()) as Map)['data'].containsKey('userMaps'),
+        isFalse,
+      );
+    });
+
+    test('byteLength 与实际编码长度一致', () {
+      final backup = AccountBackup(
+        document: buildBackupDocument(userId: 7, sections: sections),
+        failedSections: const [],
+      );
+
+      expect(backup.byteLength, utf8.encode(backup.encode()).length);
+    });
+
+    test('备份要覆盖用户点名的那几类数据', () {
+      expect(kBackupItemKinds, containsAll([1, 2, 3, 5, 6, 7, 10, 11, 12]));
+      // 15 = KaleidxScopeKey，客户端从不读它，不该出现在回读清单里。
+      expect(kBackupItemKinds, isNot(contains(15)));
+    });
+  });
+}

test/best50_poster_test.dart

@@ -16,8 +16,20 @@ List<Best50CardData> _cards(int count, {String tag = 'a'}) => [
       syncStatus: i % 5,
       ra: 50 + i,
       rate: const [
-        'D', 'C', 'B', 'BB', 'BBB', 'A', 'AA',
+        'D',
-        'AAA', 'S', 'Sp', 'SS', 'SSp', 'SSS', 'SSSp',
+        'C',
+        'B',
+        'BB',
+        'BBB',
+        'A',
+        'AA',
+        'AAA',
+        'S',
+        'Sp',
+        'SS',
+        'SSp',
+        'SSS',
+        'SSSp',
       ][i % 14],
     ),
 ];
@@ -99,7 +111,11 @@ void main() {
     testWidgets('BEST35 未打满时 BEST15 仍固定在第二区块', (tester) async {
       // 回归用例：以前按 35+15 拼接后的全局序号算行，BEST35 不满 35 条时
       // BEST15 会整体上移、混进上半区。
-      await _pumpPoster(tester, best35: _cards(3), best15: _cards(5, tag: 'b'));
+      await _pumpPoster(
+        tester,
+        best35: _cards(3),
+        best15: _cards(5, tag: 'b'),
+      );
 
       expect(tester.takeException(), isNull);
       final firstOf35 = tester.getTopLeft(find.text('a#0')).dy;
@@ -113,10 +129,9 @@ void main() {
       expect(lastOf15, greaterThanOrEqualTo(Best50Poster.gridTopSecondBlock));
     });
 
-    testWidgets('窄视口里海报仍保持底图尺寸（FittedBox 预览）', (tester) async {
+    testWidgets('constrained:false 下海报仍保持底图原尺寸', (tester) async {
-      // 回归用例：InteractiveViewer 的 constrained 默认为 true，直接把固定尺寸的
+      // InteractiveViewer(constrained:false) 会给孩子无界约束。不加限定的话
-      // 海报当子节点会被压成视口大小——底图压扁、Positioned 的卡片掉出画布被裁掉。
+      // 海报会按 1762x1850 的逻辑尺寸直接铺开，视口里只看得到左上角。
-      // 中间垫一层 FittedBox 才是对的：视口拿到的是缩放后的显示，边界录到的仍是原尺寸。
       tester.view.physicalSize = const Size(400, 900);
       tester.view.devicePixelRatio = 1.0;
       addTearDown(tester.view.reset);
@@ -151,15 +166,62 @@ void main() {
       expect(tester.takeException(), isNull);
       expect(
         tester.getSize(find.byType(Best50Poster)),
-        const Size(
+        const Size(Best50Poster.canvasWidth, Best50Poster.canvasHeight),
-          Best50Poster.canvasWidth,
-          Best50Poster.canvasHeight,
-        ),
       );
     });
 
+    testWidgets('缩放到 contain 盒子后海报仍是原尺寸（导出分辨率不受影响）', (tester) async {
+      // 页面现在用「有限大小的盒子 + FittedBox」把海报整体缩到视口内，
+      // RepaintBoundary 在 FittedBox 内侧，所以 toImage 出来的还是
+      // 1762x1850 * pixelRatio。这条守的是：别把 RepaintBoundary 挪到盒子外面。
+      tester.view.physicalSize = const Size(400, 900);
+      tester.view.devicePixelRatio = 1.0;
+      addTearDown(tester.view.reset);
+
+      // 视口 400x900，宽度是限制边，所以 contain 按宽算——和页面里的取法一致。
+      const contain = 400 / Best50Poster.canvasWidth;
+      await tester.pumpWidget(
+        MaterialApp(
+          home: Scaffold(
+            body: Center(
+              child: SizedBox(
+                width: Best50Poster.canvasWidth * contain,
+                height: Best50Poster.canvasHeight * contain,
+                child: const FittedBox(
+                  fit: BoxFit.fill,
+                  child: Best50Poster(
+                    userName: 'Test Player',
+                    iconId: 0,
+                    playerRating: 12345,
+                    best35: [],
+                    best15: [],
+                  ),
+                ),
+              ),
+            ),
+          ),
+        ),
+      );
+      await tester.pump();
+
+      expect(tester.takeException(), isNull);
+      expect(
+        tester.getSize(find.byType(Best50Poster)),
+        const Size(Best50Poster.canvasWidth, Best50Poster.canvasHeight),
+      );
+      // 显示盒子确实缩到视口内，所以一进来能看到完整一张。
+      final boxSize = tester.getSize(find.byType(FittedBox).first);
+      expect(boxSize.width, closeTo(400, 0.5));
+      expect(boxSize.height, closeTo(Best50Poster.canvasHeight * contain, 0.5));
+      expect(boxSize.height, lessThan(900));
+    });
+
     testWidgets('超出上限的条目被裁剪到 35+15', (tester) async {
-      await _pumpPoster(tester, best35: _cards(60), best15: _cards(40, tag: 'b'));
+      await _pumpPoster(
+        tester,
+        best35: _cards(60),
+        best15: _cards(40, tag: 'b'),
+      );
 
       expect(tester.takeException(), isNull);
       // BEST35 只保留前 35 条，BEST15 只保留前 15 条。