feat(client/auth): 注册页加邀请码(选填)输入,提交时传 invite_code

client/lib/widgets/auth_screen.dart

@@ -24,10 +24,14 @@ const _easeOut = Cubic(0.22, 1, 0.36, 1);
 enum _AuthMode { login, register }
 
 class AuthScreen extends ConsumerStatefulWidget {
-  const AuthScreen({super.key, required this.onDone, required this.t});
+  const AuthScreen({super.key, required this.onDone, required this.t, this.api});
   final VoidCallback onDone;
   final AppText t;
 
+  /// 测试可注入(见 test/widget/auth_invite_field_test.dart);生产不传,内部
+  /// 用 kApiBaseUrl 现建一个,行为不变。
+  final AuthApi? api;
+
   @override
   ConsumerState<AuthScreen> createState() => _AuthScreenState();
 }
@@ -44,6 +48,7 @@ class _AuthScreenState extends ConsumerState<AuthScreen>
   final _email = TextEditingController();
   final _code = TextEditingController();
   final _pw = TextEditingController();
+  final _invite = TextEditingController();
 
   final _emailFocus = FocusNode();
   final _pwFocus = FocusNode();
@@ -54,7 +59,7 @@ class _AuthScreenState extends ConsumerState<AuthScreen>
     duration: const Duration(milliseconds: 620),
   );
 
-  late final AuthApi _api = AuthApi(baseUrl: kApiBaseUrl);
+  late final AuthApi _api = widget.api ?? AuthApi(baseUrl: kApiBaseUrl);
 
   bool get _emailValid => RegExp(r'\S+@\S+\.\S+').hasMatch(_email.text);
 
@@ -79,6 +84,7 @@ class _AuthScreenState extends ConsumerState<AuthScreen>
     _email.dispose();
     _code.dispose();
     _pw.dispose();
+    _invite.dispose();
     _emailFocus.dispose();
     _pwFocus.dispose();
     _codeFocus.dispose();
@@ -108,6 +114,7 @@ class _AuthScreenState extends ConsumerState<AuthScreen>
         code: _code.text.trim(),
         password: _pw.text,
         device: device,
+        inviteCode: _invite.text.trim(),
       );
       await ref.read(tokenStoreProvider).saveLastEmail(_email.text.trim());
       await ref.read(authProvider.notifier).saveTokens(tokens);
@@ -464,6 +471,11 @@ class _AuthScreenState extends ConsumerState<AuthScreen>
       ),
       const SizedBox(height: 16),
       _field(c, icon: PangolinIcons.lock, label: t.pwLabel, focused: _pwFocus.hasFocus, child: _pwInput(c, t.setPwPh, onSubmit: _submitRegister)),
+      const SizedBox(height: 16),
+      _field(c, icon: PangolinIcons.gift, label: t.inviteCodeFieldLabel, focused: false,
+          child: TextField(key: const Key('invite-code-field'), controller: _invite,
+              textInputAction: TextInputAction.done,
+              decoration: _bare.copyWith(hintText: ''))),
       const SizedBox(height: 18),
       _primaryBtn(c, label: _loading ? '...' : t.doCreate,
           onPressed: (!_loading && _pw.text.length >= 6) ? _doRegister : null),

client/test/widget/auth_invite_field_test.dart

@@ -0,0 +1,103 @@
+// auth_invite_field_test.dart — Task 13: 注册页「邀请码(选填)」输入框
+//
+// 驱动路径:切到注册 tab(step0)→ 填邮箱 → 点发送验证码(mock 网络 204)→
+// 填 6 位验证码 → 点下一步(进 step1 设密码步)→ 断言 step1 渲染出
+// key 为 invite-code-field 的 TextField,label 为 t.inviteCodeFieldLabel。
+import 'dart:convert';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:http/http.dart' as http;
+import 'package:http/testing.dart';
+import 'package:pangolin_vpn/l10n/strings_zh.dart';
+import 'package:pangolin_vpn/pangolin_theme.dart';
+import 'package:pangolin_vpn/services/auth_api.dart';
+import 'package:pangolin_vpn/services/token_store.dart';
+import 'package:pangolin_vpn/state/auth_provider.dart';
+import 'package:pangolin_vpn/widgets/auth_screen.dart';
+
+import '../helpers/harness.dart';
+
+class _NullTokenStore implements TokenStore {
+  const _NullTokenStore();
+  @override
+  Future<void> saveTokens({required String access, required String refresh}) async {}
+  @override
+  Future<String?> loadAccessToken() async => null;
+  @override
+  Future<String?> loadRefreshToken() async => null;
+  @override
+  Future<void> clear() async {}
+  @override
+  Future<void> markOnboarded() async {}
+  @override
+  Future<bool> isOnboarded() async => true;
+  @override
+  Future<void> saveLastEmail(String email) async {}
+  @override
+  Future<String?> loadLastEmail() async => null;
+}
+
+void main() {
+  setUpAll(disableGoogleFontsFetching);
+  const t = StringsZh();
+
+  Future<void> _driveToRegisterStep1(WidgetTester tester) async {
+    final mockClient = MockClient((req) async {
+      if (req.method == 'POST' && req.url.path == '/v1/auth/code') {
+        return http.Response('', 204);
+      }
+      return http.Response(jsonEncode({'message_zh': 'unexpected'}), 404);
+    });
+    final api = AuthApi(baseUrl: 'http://test.invalid', client: mockClient);
+
+    await tester.pumpWidget(ProviderScope(
+      overrides: [tokenStoreProvider.overrideWithValue(const _NullTokenStore())],
+      child: MaterialApp(
+        debugShowCheckedModeBanner: false,
+        theme: PangolinTheme.light,
+        home: AuthScreen(t: t, onDone: () {}, api: api),
+      ),
+    ));
+    await tester.pumpAndSettle();
+
+    // 切到注册 tab。
+    await tester.tap(find.text(t.tabRegister));
+    await tester.pumpAndSettle();
+
+    // step0:填邮箱 → 点发送验证码(mock 204)。
+    await tester.enterText(find.byType(TextField).first, 'invitee@example.com');
+    await tester.pump();
+    await tester.tap(find.text(t.sendCode));
+    await tester.pumpAndSettle();
+
+    // 填 6 位验证码 → 下一步,进 step1。
+    await tester.enterText(find.byType(TextField).at(1), '123456');
+    await tester.pump();
+    await tester.tap(find.text(t.doNext));
+    await tester.pumpAndSettle();
+  }
+
+  testWidgets('注册 step1(设密码步)渲染邀请码(选填)输入框', (tester) async {
+    await _driveToRegisterStep1(tester);
+
+    expect(find.byKey(const Key('invite-code-field')), findsOneWidget);
+    expect(find.text(t.inviteCodeFieldLabel), findsOneWidget);
+  });
+
+  testWidgets('登录路径不含邀请码输入框', (tester) async {
+    final api = AuthApi(baseUrl: 'http://test.invalid', client: MockClient((req) async => http.Response('', 404)));
+    await tester.pumpWidget(ProviderScope(
+      overrides: [tokenStoreProvider.overrideWithValue(const _NullTokenStore())],
+      child: MaterialApp(
+        debugShowCheckedModeBanner: false,
+        theme: PangolinTheme.light,
+        home: AuthScreen(t: t, onDone: () {}, api: api),
+      ),
+    ));
+    await tester.pumpAndSettle();
+
+    expect(find.byKey(const Key('invite-code-field')), findsNothing);
+  });
+}