feat: add undergraduate import and exam selection screens

mobile/lib/app/app_controller.dart

@@ -134,7 +134,9 @@ class AppController extends ChangeNotifier {
   Future<void> applyImport(
     ImportDraft draft, {
     required bool confirmedEmpty,
+    bool Function()? canApply,
   }) => _run(() async {
+    if (canApply != null && !canApply()) throw StateError('学校页面已变化，请重新导入。');
     if (draft.courses.isEmpty && (!draft.explicitlyEmpty || !confirmedEmpty)) {
       throw const FormatException('未检测到课程，已有课表保持不变');
     }
@@ -202,7 +204,9 @@ class AppController extends ChangeNotifier {
     }
     await _cleanupCalendar();
   });
-  Future<void> applyExams(ExamSchedule value) => _run(() async {
+  Future<void> applyExams(ExamSchedule value, {bool Function()? canApply}) =>
+      _run(() async {
+        if (canApply != null && !canApply()) throw StateError('学校查询已取消，请重新读取。');
         final validated = ExamSchedule.fromJson(value.toJson());
         if (validated.school == SupportedSchool.uestcUndergraduate) {
           await _save(snapshot.copyWith(examSchedule: validated));

mobile/lib/features/profile/import_preview.dart

@@ -10,9 +10,11 @@ class ImportPreview extends StatefulWidget {
     super.key,
     required this.draft,
     required this.controller,
+    this.canApply,
   });
   final ImportDraft draft;
   final AppController controller;
+  final bool Function()? canApply;
   @override
   State<ImportPreview> createState() => _ImportPreviewState();
 }
@@ -41,6 +43,16 @@ class _ImportPreviewState extends State<ImportPreview> {
               style: const TextStyle(color: river),
             ),
             if (draft.semesterLabel != null) Text('学期：${draft.semesterLabel}'),
+            if (widget.controller.snapshot.courses.isNotEmpty &&
+                widget.controller.snapshot.schoolTerm != draft.schoolTerm &&
+                draft.schoolTerm != null)
+              const Padding(
+                padding: EdgeInsets.only(top: 8),
+                child: Text(
+                  '将替换当前课表；导入新学校或新学期后，请重新设置学期开始日。',
+                  style: TextStyle(fontSize: 12, height: 1.6),
+                ),
+              ),
             if (draft.schoolTerm != null)
               const Padding(
                 padding: EdgeInsets.only(top: 8),
@@ -106,6 +118,7 @@ class _ImportPreviewState extends State<ImportPreview> {
                         await widget.controller.applyImport(
                           draft,
                           confirmedEmpty: _clearConfirmed,
+                          canApply: widget.canApply,
                         );
                         if (!context.mounted) return;
                         if (widget.controller.lastError == null) {

mobile/lib/features/school/undergraduate/auth_page.dart

@@ -0,0 +1,227 @@
+import 'package:flutter/material.dart';
+import 'package:webview_flutter/webview_flutter.dart';
+
+import '../../../app/app_controller.dart';
+import '../../../data/json_schedule_import.dart';
+import '../../../domain/exam_schedule.dart';
+import '../../profile/import_preview.dart';
+import 'session.dart';
+import 'exam_query_picker.dart';
+
+class UndergraduateAuthPage extends StatefulWidget {
+  const UndergraduateAuthPage({
+    super.key,
+    required this.session,
+    required this.controller,
+  });
+  final UndergraduateSession session;
+  final AppController controller;
+  @override
+  State<UndergraduateAuthPage> createState() => _UndergraduateAuthPageState();
+}
+
+class _UndergraduateAuthPageState extends State<UndergraduateAuthPage> {
+  bool _saving = false;
+  Object? _handled;
+  String? _saveError;
+  @override
+  void initState() {
+    super.initState();
+    widget.session.addListener(_changed);
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      if (mounted) {
+        widget.session.setReadingActive(true);
+        _changed();
+      }
+    });
+  }
+
+  void _changed() {
+    if (!mounted) return;
+    setState(() {});
+    final s = widget.session, result = s.pendingDraft ?? s.pendingExams;
+    if (_saving || result == null || identical(_handled, result)) return;
+    _handled = result;
+    _saving = true;
+    final generation = s.pageGeneration;
+    WidgetsBinding.instance.addPostFrameCallback((_) async {
+      if (!mounted) return;
+      await _save(s.pendingDraft, s.pendingExams, generation);
+    });
+  }
+
+  Future<void> _save(
+    ImportDraft? draft,
+    ExamSchedule? exams,
+    int generation,
+  ) async {
+    final s = widget.session,
+        controller = widget.controller,
+        route = ModalRoute.of(context);
+    bool current() =>
+        mounted &&
+        route?.isActive == true &&
+        generation == s.pageGeneration &&
+        identical(draft, s.pendingDraft) &&
+        identical(exams, s.pendingExams);
+    try {
+      if (!current()) return;
+      var saved = false;
+      if (draft != null) {
+        final replacement =
+            controller.snapshot.courses.isNotEmpty &&
+            controller.snapshot.schoolTerm != draft.schoolTerm;
+        if (replacement || draft.courses.isEmpty) {
+          final confirmed = await showModalBottomSheet<bool>(
+            context: context,
+            isScrollControlled: true,
+            showDragHandle: true,
+            builder: (_) => ImportPreview(
+              draft: draft,
+              controller: controller,
+              canApply: current,
+            ),
+          );
+          if (!current()) return;
+          saved = confirmed == true;
+        } else {
+          await controller.applyImport(
+            draft,
+            confirmedEmpty: false,
+            canApply: current,
+          );
+          saved = controller.lastError == null;
+        }
+      } else if (exams != null) {
+        await controller.applyExams(exams, canApply: current);
+        saved = controller.lastError == null;
+      }
+      if (!current()) return;
+      if (saved && s.saved(generation: generation)) {
+        final messenger = ScaffoldMessenger.of(context);
+        if (route?.isCurrent == true) Navigator.pop(context);
+        messenger.showSnackBar(
+          SnackBar(
+            content: Text(exams == null ? '课表已导入，请核对学期开始日。' : '考试信息已更新'),
+          ),
+        );
+      } else if (controller.lastError != null) {
+        _saveError = controller.lastError;
+      }
+    } finally {
+      _saving = false;
+      if (mounted) _changed();
+    }
+  }
+
+  @override
+  void dispose() {
+    widget.session.removeListener(_changed);
+    widget.session.setReadingActive(false);
+    super.dispose();
+  }
+
+  Future<void> _changeQuery() async {
+    final value = await showUndergraduateExamQueryPicker(
+      context,
+      initial: widget.session.query,
+      now: widget.controller.clock(),
+    );
+    if (!mounted || value == null) return;
+    _handled = null;
+    _saveError = null;
+    await widget.session.openExams(value);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final s = widget.session;
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(s.requestingExams ? '本科考试查询' : '本科课表导入'),
+        actions: [
+          if (s.requestingExams)
+            IconButton(
+              tooltip: '查询选项',
+              onPressed: _saving ? null : _changeQuery,
+              icon: const Icon(Icons.tune_rounded),
+            ),
+          IconButton(
+            tooltip: '重新认证',
+            onPressed: _saving
+                ? null
+                : () {
+                    _handled = null;
+                    _saveError = null;
+                    s.reauthenticate();
+                  },
+            icon: const Icon(Icons.refresh_rounded),
+          ),
+        ],
+      ),
+      body: Column(
+        children: [
+          if (s.busy || _saving) const LinearProgressIndicator(minHeight: 2),
+          Container(
+            width: double.infinity,
+            padding: const EdgeInsets.all(12),
+            color: const Color(0xFFEFF6FF),
+            child: Text(
+              s.message,
+              style: const TextStyle(fontSize: 12, height: 1.5),
+            ),
+          ),
+          if (s.requestingExams && s.query != null)
+            Padding(
+              padding: const EdgeInsets.all(8),
+              child: Text(
+                '${s.query!.term.label} · ${s.query!.orderedTypes.map((t) => t.label).join('、')}',
+                style: const TextStyle(fontSize: 12),
+              ),
+            ),
+          if (_saveError != null)
+            Padding(
+              padding: const EdgeInsets.all(8),
+              child: Column(
+                children: [
+                  Text(_saveError!, style: const TextStyle(fontSize: 12)),
+                  TextButton(
+                    onPressed: _saving
+                        ? null
+                        : () {
+                            _saveError = null;
+                            _handled = null;
+                            _changed();
+                          },
+                    child: const Text('重试保存'),
+                  ),
+                ],
+              ),
+            ),
+          Expanded(child: WebViewWidget(controller: s.web)),
+          if (!s.requestingExams)
+            SafeArea(
+              top: false,
+              child: Padding(
+                padding: const EdgeInsets.fromLTRB(16, 8, 16, 10),
+                child: SizedBox(
+                  width: double.infinity,
+                  child: FilledButton.icon(
+                    onPressed: _saving || s.busy
+                        ? null
+                        : () {
+                            _handled = null;
+                            _saveError = null;
+                            s.readCurrentTimetable();
+                          },
+                    icon: const Icon(Icons.download_rounded),
+                    label: const Text('导入当前课表'),
+                  ),
+                ),
+              ),
+            ),
+        ],
+      ),
+    );
+  }
+}

mobile/lib/features/school/undergraduate/exam_query_picker.dart

@@ -0,0 +1,84 @@
+import 'package:flutter/material.dart';
+
+import '../../../domain/school_identity.dart';
+import '../../../domain/school_term.dart';
+import '../../../domain/undergraduate_exam_query.dart';
+
+Future<UndergraduateExamQuery?> showUndergraduateExamQueryPicker(
+  BuildContext context, {
+  UndergraduateExamQuery? initial,
+  required DateTime now,
+}) => showDialog<UndergraduateExamQuery>(
+  context: context,
+  builder: (_) => _ExamPicker(initial: initial, now: now),
+);
+
+class _ExamPicker extends StatefulWidget {
+  const _ExamPicker({this.initial, required this.now});
+  final UndergraduateExamQuery? initial;
+  final DateTime now;
+  @override
+  State<_ExamPicker> createState() => _ExamPickerState();
+}
+
+class _ExamPickerState extends State<_ExamPicker> {
+  late SchoolTerm _term =
+      widget.initial?.term ??
+      SchoolTerm(523, school: SupportedSchool.uestcUndergraduate);
+  late final Set<UndergraduateExamType> _types = {
+    ...?widget.initial?.types,
+    if (widget.initial == null) UndergraduateExamType.finalExam,
+  };
+  @override
+  Widget build(BuildContext context) => AlertDialog(
+    title: const Text('本科考试查询'),
+    content: SingleChildScrollView(
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          const Text('选择一个学期和需要查询的考试类型'),
+          const SizedBox(height: 14),
+          DropdownButton<SchoolTerm>(
+            isExpanded: true,
+            value: _term,
+            items: SchoolTerm.undergraduateChoices(widget.now, saved: _term)
+                .map((t) => DropdownMenuItem(value: t, child: Text(t.label)))
+                .toList(),
+            onChanged: (t) {
+              if (t != null) setState(() => _term = t);
+            },
+          ),
+          for (final type in UndergraduateExamType.values)
+            CheckboxListTile(
+              contentPadding: EdgeInsets.zero,
+              title: Text(type.label),
+              value: _types.contains(type),
+              onChanged: (v) => setState(() {
+                if (v == true) {
+                  _types.add(type);
+                } else {
+                  _types.remove(type);
+                }
+              }),
+            ),
+        ],
+      ),
+    ),
+    actions: [
+      TextButton(
+        onPressed: () => Navigator.pop(context),
+        child: const Text('取消'),
+      ),
+      FilledButton(
+        onPressed: _types.isEmpty
+            ? null
+            : () => Navigator.pop(
+                context,
+                UndergraduateExamQuery(term: _term, types: _types),
+              ),
+        child: const Text('开始查询'),
+      ),
+    ],
+  );
+}

mobile/test/support/fake_school_web.dart

@@ -1,9 +1,16 @@
 import 'dart:async';
+
+import 'package:flutter/widgets.dart';
+
 import 'dart:convert';
 
 import 'package:webview_flutter_platform_interface/webview_flutter_platform_interface.dart';
 
 class FakeSchoolPlatform extends WebViewPlatform {
+  @override
+  PlatformWebViewWidget createPlatformWebViewWidget(
+    PlatformWebViewWidgetCreationParams params,
+  ) => FakeSchoolWidget(params);
   int controllerCreations = 0;
   late FakeSchoolWeb web;
   late FakeSchoolDelegate delegate;
@@ -26,6 +33,13 @@ class FakeSchoolPlatform extends WebViewPlatform {
   ) => cookies;
 }
 
+class FakeSchoolWidget extends PlatformWebViewWidget {
+  FakeSchoolWidget(super.params) : super.implementation();
+  @override
+  Widget build(BuildContext context) =>
+      const SizedBox.expand(key: Key('fake-school-browser'));
+}
+
 class FakeSchoolWeb extends PlatformWebViewController {
   FakeSchoolWeb(super.params) : super.implementation();
   final loads = <String>[];

mobile/test/widgets/undergraduate_auth_test.dart

@@ -0,0 +1,128 @@
+import 'dart:io';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:webview_flutter_platform_interface/webview_flutter_platform_interface.dart';
+import 'package:hepan_everyday/features/school/undergraduate/auth_page.dart';
+import 'package:hepan_everyday/features/school/undergraduate/session.dart';
+import 'package:hepan_everyday/features/school/undergraduate/page_probe.dart';
+import 'package:hepan_everyday/app/app_controller.dart';
+import 'package:hepan_everyday/domain/app_snapshot.dart';
+import 'package:hepan_everyday/domain/school_term.dart';
+
+import '../support/fake_school_web.dart';
+import '../support/fakes.dart';
+import '../school/undergraduate_session_test.dart' show underEvidence;
+import '../domain/schedule_engine_test.dart' show course;
+
+void main() {
+  late FakeSchoolPlatform platform;
+  late UndergraduateSession session;
+  late AppController controller;
+  late MemoryStore store;
+  setUp(() {
+    platform = FakeSchoolPlatform();
+    WebViewPlatform.instance = platform;
+    session = UndergraduateSession();
+    store = MemoryStore();
+  });
+  tearDown(() {
+    session.dispose();
+    controller.dispose();
+  });
+  Future<void> open(WidgetTester tester) async {
+    controller = AppController(
+      store,
+      FakeNotifications(),
+      FakeCalendar(),
+      () => DateTime.utc(2026, 10, 14),
+    );
+    await controller.initialize(reconcileServices: false);
+    await session.openTimetable();
+    platform.web.javascript = (s) async => underEvidence(
+      platform.web.url!,
+      html: s == undergraduateCaptureScript
+          ? File('test/fixtures/school/undergraduate-timetable.html')
+                .readAsStringSync()
+          : null,
+    );
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Builder(
+          builder: (context) => Scaffold(
+            body: TextButton(
+              onPressed: () => Navigator.push(
+                context,
+                MaterialPageRoute<void>(
+                  builder: (_) => UndergraduateAuthPage(
+                    session: session,
+                    controller: controller,
+                  ),
+                ),
+              ),
+              child: const Text('打开'),
+            ),
+          ),
+        ),
+      ),
+    );
+    await tester.tap(find.text('打开'));
+    await tester.pumpAndSettle();
+  }
+
+  testWidgets('manual importer waits for the import button and then saves', (
+    tester,
+  ) async {
+    await open(tester);
+    expect(find.text('导入当前课表'), findsOneWidget);
+    expect(session.pendingDraft, isNull);
+    expect(controller.snapshot.courses, isEmpty);
+    await tester.tap(find.text('导入当前课表'));
+    await tester.pumpAndSettle();
+    expect(controller.snapshot.courses, hasLength(18));
+    expect(find.text('打开'), findsOneWidget);
+  });
+  testWidgets('cross school replacement can be cancelled without saving', (
+    tester,
+  ) async {
+    store.value = AppSnapshot(courses: [course()], schoolTerm: SchoolTerm(73));
+    await open(tester);
+    final previous = controller.snapshot.toJson();
+    await tester.tap(find.text('导入当前课表'));
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 400));
+    await tester.pump(const Duration(milliseconds: 400));
+    expect(find.text('确认你的课表'), findsOneWidget);
+    await tester.ensureVisible(find.text('取消').last);
+    await tester.pump();
+    await tester.tap(find.text('取消').last);
+    await tester.pumpAndSettle();
+    expect(controller.snapshot.toJson(), previous);
+    expect(find.text('导入当前课表'), findsOneWidget);
+  });
+  testWidgets('failed saving stays on the browser and can be retried', (
+    tester,
+  ) async {
+    await open(tester);
+    store.failSave = true;
+    await tester.tap(find.text('导入当前课表'));
+    await tester.pumpAndSettle();
+    expect(controller.snapshot.courses, isEmpty);
+    expect(find.text('重试保存'), findsOneWidget);
+    store.failSave = false;
+    await tester.tap(find.text('重试保存'));
+    await tester.pumpAndSettle();
+    expect(controller.snapshot.courses, hasLength(18));
+  });
+  testWidgets('an obsolete deferred save does not strand a newer import', (
+    tester,
+  ) async {
+    await open(tester);
+    await tester.tap(find.text('导入当前课表'));
+    await session.openTimetable();
+    await session.readCurrentTimetable();
+    platform.delegate.finished(platform.web.url!);
+    await tester.pumpAndSettle();
+    expect(controller.snapshot.courses, hasLength(18));
+  });
+}

mobile/test/widgets/undergraduate_exam_picker_test.dart

@@ -0,0 +1,90 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:hepan_everyday/features/school/undergraduate/exam_query_picker.dart';
+import 'package:hepan_everyday/domain/undergraduate_exam_query.dart';
+import 'package:hepan_everyday/domain/school_term.dart';
+import 'package:hepan_everyday/domain/school_identity.dart';
+
+void main() {
+  testWidgets('exam picker keeps one semester and requires at least one type', (
+    tester,
+  ) async {
+    UndergraduateExamQuery? result;
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Builder(
+          builder: (context) => Scaffold(
+            body: TextButton(
+              onPressed: () async {
+                result = await showUndergraduateExamQueryPicker(
+                  context,
+                  now: DateTime(2026, 10),
+                );
+              },
+              child: const Text('选择'),
+            ),
+          ),
+        ),
+      ),
+    );
+    await tester.tap(find.text('选择'));
+    await tester.pumpAndSettle();
+    expect(find.text('2026-2027第一学期'), findsOneWidget);
+    await tester.tap(find.text('期末考试'));
+    await tester.pump();
+    expect(
+      tester
+          .widget<FilledButton>(find.widgetWithText(FilledButton, '开始查询'))
+          .onPressed,
+      isNull,
+    );
+    await tester.tap(find.text('期中考试'));
+    await tester.tap(find.text('补考/缓考'));
+    await tester.pump();
+    await tester.tap(find.text('开始查询'));
+    await tester.pumpAndSettle();
+    expect(result!.term.id, 523);
+    expect(result!.types, {
+      UndergraduateExamType.midterm,
+      UndergraduateExamType.makeup,
+    });
+  });
+  testWidgets('saved term and exam types persist and cancel returns null', (
+    tester,
+  ) async {
+    final initial = UndergraduateExamQuery(
+      term: SchoolTerm(503, school: SupportedSchool.uestcUndergraduate),
+      types: {UndergraduateExamType.midterm},
+    );
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Builder(
+          builder: (context) => Scaffold(
+            body: TextButton(
+              onPressed: () => showUndergraduateExamQueryPicker(
+                context,
+                initial: initial,
+                now: DateTime(2026, 10),
+              ),
+              child: const Text('选择'),
+            ),
+          ),
+        ),
+      ),
+    );
+    await tester.tap(find.text('选择'));
+    await tester.pumpAndSettle();
+    expect(find.text('2025-2026第二学期'), findsOneWidget);
+    expect(
+      tester
+          .widget<CheckboxListTile>(
+            find.widgetWithText(CheckboxListTile, '期中考试'),
+          )
+          .value,
+      isTrue,
+    );
+    await tester.tap(find.text('取消'));
+    await tester.pumpAndSettle();
+    expect(find.text('开始查询'), findsNothing);
+  });
+}