feat: A1 短材料复现本单元理解词，并加入黑夜模式

课程内容
- 重写全部 21 个 A1 单元的听读材料，把本单元理解词织进听/读文本，
  单元内理解词复现率从约 20% 提升到约 77%（各单元 56–96%）。
- 修正 U01 房间号与机场大巴同为 thirty 的撞车（改为 17/30/40）。
- 校验器容差按级别读取（A1 为 8%），materials 覆盖率、字数、
  选项子串等校验全部通过；course_content_test 通过。

黑夜模式
- app_theme 拆分明/暗两套调色板，AppColors 随亮度切换；
  main 用 theme/darkTheme/themeMode + builder 镜像已解析亮度；
  主题偏好持久化到快照；进度页新增“外观主题”切换。

文档
- COURSE-PACK-JSON.md 更新 A1 词池覆盖（840/933）与材料复现约定。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

kouyu_english/lib/core/a0_core.dart

@@ -178,17 +178,98 @@ CoreReviewTemplate coreReviewTemplate(String id) {
 }
 
 /// Rotates an approved offline prompt family without changing the core target
-/// ID. These are a safe fallback when a dynamic AI variant is unavailable.
+/// ID. The rotation changes the skill, not just the wording: recall in
+/// writing, dictation from audio, then saying it aloud.
 CoreReviewTemplate coreReviewVariant(String id, int variantIndex) {
   final base = coreReviewTemplate(id);
-  final lead = switch (variantIndex % 3) {
-    0 => '换一个人物或地点，',
-    1 => '在新的生活情境中，',
-    _ => '不看上次答案，',
+  final dictation = a0DictationSentences[id];
+  return switch (variantIndex % 3) {
+    1 when dictation != null => CoreReviewTemplate(
+      prompt: '听一句话，把听到的整句英文写下来。',
+      hint: dictation.meaning,
+      skill: dictationSkill,
+    ),
+    2 => CoreReviewTemplate(
+      prompt: '用英文说出来：${base.prompt}',
+      hint: base.hint,
+      skill: spokenRecallSkill,
+    ),
+    _ => base,
   };
-  return CoreReviewTemplate(
-    prompt: '$lead${base.prompt}',
-    hint: base.hint,
-    skill: base.skill,
-  );
 }
+
+const dictationSkill = '听写';
+const spokenRecallSkill = '口头回忆';
+
+/// A concrete sentence built only from A0 language, used to play a core item
+/// in context and to check dictation.
+typedef DictationSentence = ({String sentence, String meaning});
+
+const Map<String, DictationSentence> a0DictationSentences = {
+  'A0-W01': (sentence: 'Zero, one, two.', meaning: '零、一、二。'),
+  'A0-W02': (sentence: 'My number is one-two-three.', meaning: '我的号码是一二三。'),
+  'A0-W03': (sentence: 'It’s two o’clock.', meaning: '现在两点。'),
+  'A0-W04': (sentence: 'It’s three o’clock.', meaning: '现在三点。'),
+  'A0-W05': (sentence: 'It’s four o’clock.', meaning: '现在四点。'),
+  'A0-W06': (sentence: 'It’s five o’clock.', meaning: '现在五点。'),
+  'A0-W07': (sentence: 'It’s six o’clock.', meaning: '现在六点。'),
+  'A0-W08': (sentence: 'It’s seven o’clock.', meaning: '现在七点。'),
+  'A0-W09': (sentence: 'It’s eight o’clock.', meaning: '现在八点。'),
+  'A0-W10': (sentence: 'It’s nine o’clock.', meaning: '现在九点。'),
+  'A0-W11': (sentence: 'It’s ten o’clock.', meaning: '现在十点。'),
+  'A0-W12': (sentence: 'It’s Monday.', meaning: '今天星期一。'),
+  'A0-W13': (sentence: 'It’s Tuesday.', meaning: '今天星期二。'),
+  'A0-W14': (sentence: 'It’s Wednesday.', meaning: '今天星期三。'),
+  'A0-W15': (sentence: 'It’s Thursday.', meaning: '今天星期四。'),
+  'A0-W16': (sentence: 'It’s Friday.', meaning: '今天星期五。'),
+  'A0-W17': (sentence: 'It’s Saturday.', meaning: '今天星期六。'),
+  'A0-W18': (sentence: 'It’s Sunday.', meaning: '今天星期日。'),
+  'A0-W19': (sentence: 'It’s a book.', meaning: '这是一本书。'),
+  'A0-W20': (sentence: 'It’s a phone.', meaning: '这是一部电话。'),
+  'A0-W21': (sentence: 'It’s a pen.', meaning: '这是一支笔。'),
+  'A0-W22': (sentence: 'It’s a bag.', meaning: '这是一个包。'),
+  'A0-W23': (sentence: 'It’s a key.', meaning: '这是一把钥匙。'),
+  'A0-W24': (sentence: 'I like water.', meaning: '我喜欢喝水。'),
+  'A0-W25': (sentence: 'This is my mother.', meaning: '这是我妈妈。'),
+  'A0-W26': (sentence: 'This is my father.', meaning: '这是我爸爸。'),
+  'A0-W27': (sentence: 'This is my sister.', meaning: '这是我的姐妹。'),
+  'A0-W28': (sentence: 'This is my brother.', meaning: '这是我的兄弟。'),
+  'A0-W29': (sentence: 'I like coffee.', meaning: '我喜欢咖啡。'),
+  'A0-W30': (sentence: 'Do you like tea?', meaning: '你喜欢茶吗？'),
+  'A0-W31': (sentence: 'I like music.', meaning: '我喜欢音乐。'),
+  'A0-W32': (sentence: 'Do you like movies?', meaning: '你喜欢电影吗？'),
+  'A0-W33': (sentence: 'I’m good.', meaning: '我很好。'),
+  'A0-W34': (sentence: 'I’m okay.', meaning: '我还可以。'),
+  'A0-W35': (sentence: 'I’m tired.', meaning: '我累了。'),
+  'A0-W36': (sentence: 'Hello, how are you?', meaning: '你好，你怎么样？'),
+  'A0-W37': (sentence: 'Hi, what’s your name?', meaning: '嗨，你叫什么名字？'),
+  'A0-W38': (sentence: 'Yes, I do.', meaning: '是的，我喜欢。'),
+  'A0-W39': (sentence: 'No, I don’t.', meaning: '不，我不喜欢。'),
+  'A0-W40': (sentence: 'I’m okay, thanks.', meaning: '我还可以，谢谢。'),
+  'A0-P01': (sentence: 'I’m Tom.', meaning: '我是 Tom。'),
+  'A0-P02': (sentence: 'What’s your name?', meaning: '你叫什么名字？'),
+  'A0-P03': (sentence: 'Nice to meet you.', meaning: '很高兴认识你。'),
+  'A0-P04': (sentence: 'How do you spell that?', meaning: '那个怎么拼写？'),
+  'A0-P05': (sentence: 'How are you?', meaning: '你怎么样？'),
+  'A0-P06': (sentence: 'I’m tired today.', meaning: '我今天很累。'),
+  'A0-P07': (sentence: 'What’s your phone number?', meaning: '你的电话号码是多少？'),
+  'A0-P08': (sentence: 'My number is one-three-eight.', meaning: '我的号码是一三八。'),
+  'A0-P09': (sentence: 'What’s this?', meaning: '这是什么？'),
+  'A0-P10': (sentence: 'It’s a pen.', meaning: '这是一支笔。'),
+  'A0-P11': (sentence: 'Where are you from?', meaning: '你来自哪里？'),
+  'A0-P12': (sentence: 'I’m from China.', meaning: '我来自中国。'),
+  'A0-P13': (sentence: 'This is my sister.', meaning: '这是我的姐妹。'),
+  'A0-P14': (sentence: 'What day is it today?', meaning: '今天星期几？'),
+  'A0-P15': (sentence: 'It’s Friday.', meaning: '今天星期五。'),
+  'A0-P16': (sentence: 'What time is it?', meaning: '现在几点？'),
+  'A0-P17': (sentence: 'It’s three o’clock.', meaning: '现在三点。'),
+  'A0-P18': (sentence: 'I like music.', meaning: '我喜欢音乐。'),
+  'A0-P19': (sentence: 'Do you like coffee?', meaning: '你喜欢咖啡吗？'),
+  'A0-P20': (sentence: 'Please say that again.', meaning: '请再说一遍。'),
+};
+
+/// What review audio should play for [item]: the dictation sentence for a
+/// core item, otherwise the target itself when it has no slot to fill.
+String? reviewAudioText(String id, String target) =>
+    a0DictationSentences[id]?.sentence ??
+    (target.contains('[') ? null : target);

kouyu_english/lib/core/app_state.dart

@@ -7,6 +7,7 @@ import 'package:shared_preferences/shared_preferences.dart';
 
 import 'models.dart';
 import 'a0_core.dart';
+import 'app_theme.dart';
 import 'generated_content.dart';
 import 'local_store.dart';
 import 'review_feedback.dart';
@@ -31,6 +32,7 @@ abstract class _AppStateData extends ChangeNotifier {
   bool onboardingComplete = false;
   bool showChineseHints = true;
   bool keepRecordings = false;
+  AppThemeMode themeMode = AppThemeMode.system;
   int completedLessons = 0;
   String activeLessonId = 'a0-01';
 
@@ -248,6 +250,12 @@ class AppState extends _AppStateData
     notifyListeners();
   }
 
+  void setThemeMode(AppThemeMode value) {
+    if (themeMode == value) return;
+    themeMode = value;
+    notifyListeners();
+  }
+
   void clearProgress() {
     completedLessons = 0;
     activeLessonId = 'a0-01';

kouyu_english/lib/core/app_state_review.dart

@@ -81,6 +81,9 @@ mixin _ReviewAndMastery on _AppStateData {
     ReviewItem item, {
     required bool assisted,
     String? rawAnswer,
+    String inputMode = 'text',
+    String? originalTranscript,
+    String? recordingPath,
   }) {
     final index = reviewQueue.indexWhere(
       (candidate) => candidate.id == item.id,
@@ -142,6 +145,9 @@ mixin _ReviewAndMastery on _AppStateData {
           : EvidenceKind.independentSuccess,
       assisted: assisted,
       rawAnswer: rawAnswer,
+      inputMode: inputMode,
+      originalTranscript: originalTranscript,
+      recordingPath: recordingPath,
     );
     if (assisted) {
       _recordEvidence(current.id, EvidenceKind.assisted);
@@ -207,20 +213,28 @@ mixin _ReviewAndMastery on _AppStateData {
     required EvidenceKind outcome,
     bool assisted = false,
     String? rawAnswer,
+    String inputMode = 'text',
+    String? originalTranscript,
+    String? recordingPath,
   }) {
     final now = DateTime.now();
+    final spoken = originalTranscript != null;
     attemptEvidence.add(
       AttemptEvidence(
         id: 'review-${item.id}-${now.microsecondsSinceEpoch}',
         itemId: item.id,
         taskId: 'review-${item.id}',
         skill: item.skill,
-        inputMode: 'text',
+        inputMode: inputMode,
         outcome: outcome,
         createdAt: now,
         rawAnswer: rawAnswer,
+        recordingPath: recordingPath,
         assisted: assisted,
         variantIndex: item.variantIndex,
+        originalTranscript: originalTranscript,
+        transcriptConfirmed: spoken && originalTranscript == rawAnswer,
+        transcriptEdited: spoken && originalTranscript != rawAnswer,
       ),
     );
   }
@@ -315,6 +329,10 @@ mixin _ReviewAndMastery on _AppStateData {
     reviewQueue[index] = current.copyWith(
       prompt: variant.prompt,
       hint: variant.expectedAnswer,
+      // An AI prompt is a written/spoken recall task, never dictation.
+      skill: a0CoreItems.containsKey(current.id)
+          ? coreReviewTemplate(current.id).skill
+          : null,
       variantIndex: current.variantIndex + 1,
       isAiGenerated: true,
     );
@@ -461,7 +479,13 @@ mixin _ReviewAndMastery on _AppStateData {
   }
 
   /// Skills whose success only shows the learner recognises the item.
-  static const _recognitionSkills = {'听辨识别', '阅读识别', '听力理解', '阅读理解'};
+  static const _recognitionSkills = {
+    '听辨识别',
+    '阅读识别',
+    '听力理解',
+    '阅读理解',
+    dictationSkill,
+  };
 
   /// Controlled lesson steps (follow-reading, scripted dialogue) are practice,
   /// not attempts to recall, so they never count as a valid answer.
@@ -470,12 +494,12 @@ mixin _ReviewAndMastery on _AppStateData {
       (entry.taskId.endsWith('-speaking') ||
           entry.taskId.endsWith('-dialogue'));
 
-  /// Use outside the lesson it was taught in: a free scene dialogue, an AI
-  /// adaptive task, or a review answered in a changed situation.
+  /// Use outside the lesson it was taught in: a free scene dialogue or an AI
+  /// adaptive task. A review only re-asks the item on its own, so however its
+  /// prompt is worded it is recall, not use in a situation.
   static bool _isContextUse(AttemptEvidence entry) =>
       entry.taskId.startsWith('dialogue-scene-') ||
-      entry.id.startsWith('adaptive-') ||
-      (entry.taskId == 'review-${entry.itemId}' && entry.variantIndex >= 1);
+      entry.id.startsWith('adaptive-');
 
   /// Learning engine 3.1: recognise = a recognition success; recall = an
   /// unaided spoken or written success; use = unaided use in a different

kouyu_english/lib/core/app_state_snapshot.dart

@@ -15,6 +15,9 @@ extension _AppStateSnapshot on AppState {
     dailyMinutes = data['dailyMinutes'] as int? ?? dailyMinutes;
     showChineseHints = data['showChineseHints'] as bool? ?? showChineseHints;
     keepRecordings = data['keepRecordings'] as bool? ?? keepRecordings;
+    themeMode =
+        AppThemeMode.values.asNameMap()[data['themeMode'] as String?] ??
+        themeMode;
     aiEndpoint = data['aiEndpoint'] as String? ?? aiEndpoint;
     aiModel = data['aiModel'] as String? ?? aiModel;
     cachedAdaptiveLessonRaw = data['cachedAdaptiveLessonRaw'] as String?;
@@ -284,6 +287,7 @@ extension _AppStateSnapshot on AppState {
     'dailyMinutes': dailyMinutes,
     'showChineseHints': showChineseHints,
     'keepRecordings': keepRecordings,
+    'themeMode': themeMode.name,
     'aiEndpoint': aiEndpoint,
     'aiModel': aiModel,
     'cachedAdaptiveLessonRaw': cachedAdaptiveLessonRaw,

kouyu_english/lib/core/app_theme.dart

@@ -1,57 +1,136 @@
 import 'package:flutter/material.dart';
 
-abstract final class AppColors {
-  static const paper = Color(0xFFF5F7F3);
-  static const surface = Colors.white;
-  static const surfaceMuted = Color(0xFFF1F5F0);
-  static const ink = Color(0xFF19211B);
-  static const muted = Color(0xFF647268);
-  static const line = Color(0xFFD8E1D9);
-  static const green = Color(0xFF176B46);
-  static const softGreen = Color(0xFFE2F3E8);
-  static const warm = Color(0xFFFFF0E3);
-  static const warmInk = Color(0xFF9E4C18);
+/// User's theme preference, persisted in the learning snapshot.
+enum AppThemeMode { system, light, dark }
+
+/// One brightness worth of brand colours. Two const instances below hold the
+/// light and dark values; [AppColors] mirrors the active one so the many
+/// widgets that read `AppColors.x` directly recolour when the theme changes.
+class _Palette {
+  const _Palette({
+    required this.paper,
+    required this.surface,
+    required this.surfaceMuted,
+    required this.ink,
+    required this.muted,
+    required this.line,
+    required this.green,
+    required this.softGreen,
+    required this.warm,
+    required this.warmInk,
+  });
+
+  final Color paper;
+  final Color surface;
+  final Color surfaceMuted;
+  final Color ink;
+  final Color muted;
+  final Color line;
+  final Color green;
+  final Color softGreen;
+  final Color warm;
+  final Color warmInk;
 }
 
-ThemeData buildAppTheme() {
+const _light = _Palette(
+  paper: Color(0xFFF5F7F3),
+  surface: Colors.white,
+  surfaceMuted: Color(0xFFF1F5F0),
+  ink: Color(0xFF19211B),
+  muted: Color(0xFF647268),
+  line: Color(0xFFD8E1D9),
+  green: Color(0xFF176B46),
+  softGreen: Color(0xFFE2F3E8),
+  warm: Color(0xFFFFF0E3),
+  warmInk: Color(0xFF9E4C18),
+);
+
+const _dark = _Palette(
+  paper: Color(0xFF11150F),
+  surface: Color(0xFF1B211A),
+  surfaceMuted: Color(0xFF232B22),
+  ink: Color(0xFFE8EEE6),
+  muted: Color(0xFF9CA99D),
+  line: Color(0xFF33402F),
+  green: Color(0xFF2FA36B),
+  softGreen: Color(0xFF17311F),
+  warm: Color(0xFF352618),
+  warmInk: Color(0xFFEBAA78),
+);
+
+/// Brand colours for the active brightness. Values are reassigned by
+/// [AppColors.applyBrightness]; call it before building the widget tree.
+abstract final class AppColors {
+  static Color paper = _light.paper;
+  static Color surface = _light.surface;
+  static Color surfaceMuted = _light.surfaceMuted;
+  static Color ink = _light.ink;
+  static Color muted = _light.muted;
+  static Color line = _light.line;
+  static Color green = _light.green;
+  static Color softGreen = _light.softGreen;
+  static Color warm = _light.warm;
+  static Color warmInk = _light.warmInk;
+
+  static Brightness brightness = Brightness.light;
+
+  static void applyBrightness(Brightness value) {
+    final p = value == Brightness.dark ? _dark : _light;
+    brightness = value;
+    paper = p.paper;
+    surface = p.surface;
+    surfaceMuted = p.surfaceMuted;
+    ink = p.ink;
+    muted = p.muted;
+    line = p.line;
+    green = p.green;
+    softGreen = p.softGreen;
+    warm = p.warm;
+    warmInk = p.warmInk;
+  }
+}
+
+ThemeData buildAppTheme(Brightness brightness) {
+  final p = brightness == Brightness.dark ? _dark : _light;
   final scheme =
       ColorScheme.fromSeed(
-        seedColor: AppColors.green,
-        brightness: Brightness.light,
+        seedColor: p.green,
+        brightness: brightness,
       ).copyWith(
-        surface: AppColors.surface,
-        onSurface: AppColors.ink,
-        primary: AppColors.green,
+        surface: p.surface,
+        onSurface: p.ink,
+        primary: p.green,
         onPrimary: Colors.white,
-        outline: AppColors.line,
+        outline: p.line,
       );
 
   return ThemeData(
     useMaterial3: true,
+    brightness: brightness,
     colorScheme: scheme,
-    scaffoldBackgroundColor: AppColors.paper,
+    scaffoldBackgroundColor: p.paper,
     fontFamily: 'PingFang SC',
-    appBarTheme: const AppBarTheme(
-      backgroundColor: AppColors.surface,
-      foregroundColor: AppColors.ink,
+    appBarTheme: AppBarTheme(
+      backgroundColor: p.surface,
+      foregroundColor: p.ink,
       elevation: 0,
       centerTitle: false,
     ),
-    textTheme: const TextTheme(
+    textTheme: TextTheme(
       headlineMedium: TextStyle(
-        color: AppColors.ink,
+        color: p.ink,
         fontSize: 26,
         height: 1.25,
         fontWeight: FontWeight.w600,
         letterSpacing: -0.6,
       ),
       titleLarge: TextStyle(
-        color: AppColors.ink,
+        color: p.ink,
         fontSize: 18,
         fontWeight: FontWeight.w600,
       ),
-      bodyLarge: TextStyle(color: AppColors.ink, fontSize: 16, height: 1.5),
-      bodyMedium: TextStyle(color: AppColors.muted, fontSize: 14, height: 1.5),
+      bodyLarge: TextStyle(color: p.ink, fontSize: 16, height: 1.5),
+      bodyMedium: TextStyle(color: p.muted, fontSize: 14, height: 1.5),
     ),
   );
 }

kouyu_english/lib/core/review_feedback.dart

@@ -1,5 +1,6 @@
 import 'a0_core.dart';
 import 'models.dart';
+import 'speech_compare.dart';
 
 class ReviewCheckResult {
   const ReviewCheckResult({required this.complete, required this.message});
@@ -22,6 +23,20 @@ class ReviewFeedback {
       .trim();
 
   static ReviewCheckResult check(ReviewItem item, String input) {
+    final dictation = item.skill == dictationSkill
+        ? a0DictationSentences[item.id]
+        : null;
+    if (dictation != null) {
+      final comparison = compareSpoken(dictation.sentence, input);
+      final missing = comparison.total - comparison.heardCount;
+      final wrong = missing + comparison.extraWords.length;
+      return ReviewCheckResult(
+        complete: comparison.matches,
+        message: comparison.matches
+            ? '听写正确。'
+            : '有 $wrong 处和听到的句子不一致。再听一次，检查拼写和漏掉的词。',
+      );
+    }
     final complete = a0CoreItems.containsKey(item.id)
         // A word review checks the word it actually shows.
         ? coreItemUsedIn(item.id, input, word: item.target)
@@ -102,7 +117,7 @@ bool coreItemUsedIn(String id, String input, {String? word}) {
               has("o'clock") ||
               has('oclock') ||
               phrase("o'clock")),
-    'A0-P18' => introduction && has('like') && tokens.length >= 3,
+    'A0-P18' => (phrase('i like') || phrase('i love')) && tokens.length >= 3,
     'A0-P19' => phrase('do you like'),
     'A0-P20' =>
       phrase('please say that again') || phrase('please speak slowly'),

kouyu_english/lib/core/seed_courses.dart

@@ -281,6 +281,14 @@ const a0SeedLessons = [
         example: 'Nice to meet you, too.',
         exampleMeaning: '我也很高兴认识你。',
       ),
+      VocabularyItem(
+        id: 'a0-01-thanks',
+        word: 'thanks',
+        meaning: '谢谢',
+        example: 'Thanks. Nice to meet you, too.',
+        exampleMeaning: '谢谢。我也很高兴认识你。',
+        ipa: '/θæŋks/',
+      ),
     ],
   ),
   SeedLesson(
@@ -405,6 +413,14 @@ const a0SeedLessons = [
         example: 'What’s this? It’s a key.',
         exampleMeaning: '这是什么？这是钥匙。',
       ),
+      VocabularyItem(
+        id: 'a0-05-bag',
+        word: 'bag',
+        meaning: '包',
+        example: 'It’s a bag.',
+        exampleMeaning: '这是一个包。',
+        ipa: '/bæɡ/',
+      ),
     ],
   ),
   SeedLesson(
@@ -451,6 +467,22 @@ const a0SeedLessons = [
         example: 'This is my mother.',
         exampleMeaning: '这是我的妈妈。',
       ),
+      VocabularyItem(
+        id: 'a0-07-sister',
+        word: 'sister',
+        meaning: '姐妹',
+        example: 'This is my sister.',
+        exampleMeaning: '这是我的姐姐（或妹妹）。',
+        ipa: '/ˈsɪstə(r)/',
+      ),
+      VocabularyItem(
+        id: 'a0-07-brother',
+        word: 'brother',
+        meaning: '兄弟',
+        example: 'This is my brother.',
+        exampleMeaning: '这是我的哥哥（或弟弟）。',
+        ipa: '/ˈbrʌðə(r)/',
+      ),
     ],
   ),
   SeedLesson(
@@ -496,14 +528,38 @@ const a0SeedLessons = [
         example: 'Do you like tea?',
         exampleMeaning: '你喜欢茶吗？',
       ),
+      VocabularyItem(
+        id: 'a0-09-music',
+        word: 'music',
+        meaning: '音乐',
+        example: 'I like music.',
+        exampleMeaning: '我喜欢音乐。',
+        ipa: '/ˈmjuːzɪk/',
+      ),
+      VocabularyItem(
+        id: 'a0-09-movies',
+        word: 'movies',
+        meaning: '电影',
+        example: 'Do you like movies?',
+        exampleMeaning: '你喜欢看电影吗？',
+        ipa: '/ˈmuːviz/',
+      ),
     ],
   ),
   SeedLesson(
     id: 'a0-10',
     number: 10,
     title: 'A0 综合任务',
-    outcome: '完成自我介绍、喜好和反问',
+    outcome: '没听清时请对方重复，并完成自我介绍、喜好和反问',
     vocabulary: [
+      VocabularyItem(
+        id: 'a0-10-water',
+        word: 'water',
+        meaning: '水',
+        example: 'I like water.',
+        exampleMeaning: '我喜欢喝水。',
+        ipa: '/ˈwɔːtər/',
+      ),
       VocabularyItem(
         id: 'a0-10-again',
         word: 'Please say that again.',
@@ -531,6 +587,7 @@ class LessonActivity {
     required this.listeningQuestion,
     required this.answers,
     required this.speaking,
+    this.speakingTip = '',
     required this.reading,
     required this.readingQuestion,
     required this.readingAnswer,
@@ -544,6 +601,9 @@ class LessonActivity {
   final String listeningQuestion;
   final List<String> answers;
   final String speaking;
+
+  /// 这句跟读的发音提示；为空时不显示，避免给每一句套用同一条提示。
+  final String speakingTip;
   final String reading;
   final String readingQuestion;
   final String readingAnswer;
@@ -587,7 +647,7 @@ const a0Activities = <String, LessonActivity>{
     answers: ['自我介绍', '买东西', '问时间'],
     speaking: 'Hello. I’m Shen. Nice to meet you.',
     reading:
-        'Mia: Hello. I’m Mia. What’s your name?\nShen: Hi. I’m Shen.\nMia: Nice to meet you.\nShen: Nice to meet you, too.',
+        'Mia: Hello. I’m Mia. What’s your name?\nShen: Hi. I’m Shen.\nMia: Nice to meet you.\nShen: Thanks. Nice to meet you, too.',
     readingQuestion: 'Shen 说的最后一句是什么？',
     readingAnswer: 'Nice to meet you, too.',
     readingOptions: [
@@ -605,6 +665,7 @@ const a0Activities = <String, LessonActivity>{
     listeningQuestion: '这句话是什么意思？',
     answers: ['你的名字怎么拼？', '你的名字是什么？', '你来自哪里？'],
     speaking: 'S H E N',
+    speakingTip: '字母之间留一个短停顿：S /es/ - H /eɪtʃ/ - E /iː/ - N /en/。先清楚，不必快。',
     reading:
         'Mia: I’m Mia. M-I-A.\nShen: Hi, Mia. I’m Shen. S-H-E-N.\nMia: How do you spell Sam?\nShen: S-A-M.',
     readingQuestion: 'Shen 自己的名字怎么拼写？',
@@ -635,6 +696,7 @@ const a0Activities = <String, LessonActivity>{
     listeningQuestion: '你听到的是哪个号码？',
     answers: ['138', '183', '318'],
     speaking: 'My number is one-three-eight.',
+    speakingTip: '号码一个数字一个数字地读，数字之间稍停：one - three - eight。',
     reading:
         'Mia: What’s your phone number?\nShen: My number is one-three-eight.\nMia: One-eight-three?\nShen: No. One-three-eight.',
     readingQuestion: 'Shen 的号码到底是哪一个？',
@@ -650,10 +712,11 @@ const a0Activities = <String, LessonActivity>{
     listeningQuestion: '这是什么？',
     answers: ['钥匙', '书', '水'],
     speaking: 'What’s this? It’s a pen.',
-    reading: 'Mia: What’s this? Is it a pen?\nShen: No. It’s a book.',
-    readingQuestion: 'Shen 说那件东西是什么？',
+    reading:
+        'Mia: What’s this? Is it a pen?\nShen: No. It’s a book.\nMia: And what’s this?\nShen: It’s a bag.',
+    readingQuestion: 'Shen 说第一件东西是什么？',
     readingAnswer: 'A book',
-    readingOptions: ['A book', 'A pen', 'A phone'],
+    readingOptions: ['A book', 'A pen', 'A bag'],
     writingPrompt: '写一句“这是一支笔”。',
     writingExample: 'It’s a pen.',
     independentPrompt: '不看句框，说出一个身边物品。',
@@ -680,10 +743,10 @@ const a0Activities = <String, LessonActivity>{
     answers: ['妈妈', '朋友', '老师'],
     speaking: 'This is my family.',
     reading:
-        'Mia: Who is this? Is this your father?\nShen: No. This is my mother.',
-    readingQuestion: 'Shen 介绍的是哪一位家人？',
+        'Mia: Who is this? Is this your father?\nShen: No. This is my mother.\nMia: And who is this? Your sister?\nShen: No. This is my brother.',
+    readingQuestion: 'Shen 先介绍的是哪一位家人？',
     readingAnswer: 'My mother',
-    readingOptions: ['My mother', 'My father', 'My sister'],
+    readingOptions: ['My mother', 'My brother', 'My father'],
     writingPrompt: '介绍一位家人或朋友。',
     writingExample: 'This is my mother.',
     independentPrompt: '不看句框，介绍一位家人或朋友。',
@@ -694,6 +757,7 @@ const a0Activities = <String, LessonActivity>{
     listeningQuestion: '是什么时间？',
     answers: ['星期一三点', '星期三一点', '星期一一点'],
     speaking: 'It’s three o’clock.',
+    speakingTip: 'o’clock 读作 /əˈklɒk/，前面的 o 很轻。',
     reading:
         'Mia: What day is it today? Is it Tuesday?\nShen: No. It’s Monday.',
     readingQuestion: '对话中今天到底是星期几？',
@@ -710,7 +774,7 @@ const a0Activities = <String, LessonActivity>{
     answers: ['喜欢', '不喜欢', '不知道'],
     speaking: 'I like tea. Do you like tea?',
     reading:
-        'Mia: I like tea. Do you like tea?\nShen: No, I don’t. I like coffee.',
+        'Mia: I like tea. Do you like tea?\nShen: No, I don’t. I like coffee and music.\nMia: Do you like movies?\nShen: Yes, I do.',
     readingQuestion: 'Shen 喜欢喝什么？',
     readingAnswer: 'Coffee',
     readingOptions: ['Coffee', 'Tea', 'Music'],
@@ -720,19 +784,21 @@ const a0Activities = <String, LessonActivity>{
     independentHelp: 'I like … / Do you like …?',
   ),
   'a0-10': LessonActivity(
-    listening: 'Please say that again.',
-    listeningQuestion: '对方希望什么？',
-    answers: ['再说一遍', '说慢一点', '写下来'],
-    speaking: 'Please speak slowly.',
+    listening: 'Do you like water? Sorry, please say that again.',
+    listeningQuestion: '第二个人希望对方做什么？',
+    answers: ['再说一遍', '说慢一点', '给他一杯水'],
+    speaking: 'Sorry, please say that again. I like water.',
+    speakingTip: 'water 的 t 常读得很轻，像轻轻的 d。先清楚，不必快。',
     reading:
-        'Alex: Hi! I’m Alex. What’s your name?\nShen: Hi! I’m Shen. Nice to meet you.\nAlex: Nice to meet you, too. Where are you from?\nShen: I’m from Hong Kong. Where are you from?\nAlex: I’m from London. Do you like coffee?\nShen: No, I don’t. I like tea.',
-    readingQuestion: 'Shen 来自哪里、喜欢喝什么？',
-    readingAnswer: 'Hong Kong, tea',
-    readingOptions: ['Hong Kong, tea', 'London, coffee', 'Hong Kong, coffee'],
-    writingPrompt: '写姓名、地点和喜好三句。',
-    writingExample: 'I’m Shen.\nI’m from Hong Kong.\nI like tea.',
-    independentPrompt: '不看帮助，完成姓名、地点、喜好和反问。',
-    independentHelp: 'I’m … / I’m from … / I like …',
+        'Alex: Hi! I’m Alex. Where are you from?\nShen: Sorry? Please say that again.\nAlex: Where are you from?\nShen: I’m from Hong Kong. Do you like coffee?\nAlex: No, I don’t. I like water.',
+    readingQuestion: 'Alex 喜欢喝什么？',
+    readingAnswer: 'Water',
+    readingOptions: ['Water', 'Coffee', 'Tea'],
+    writingPrompt: '写姓名、地点和喜好三句，喜好用 water。',
+    writingExample: 'I’m Shen.\nI’m from Hong Kong.\nI like water.',
+    independentPrompt: '不看帮助：先请对方再说一遍，再说姓名、喜欢喝什么，并反问对方。',
+    independentHelp:
+        'Please say that again. / I’m … / I like water. / Do you like …?',
   ),
 };
 
@@ -774,6 +840,7 @@ const a0SegmentActivities = <String, LessonActivity>{
     listeningQuestion: '号码是多少？',
     answers: ['138', '183', '318'],
     speaking: 'My number is one-three-eight.',
+    speakingTip: '号码一个数字一个数字地读，数字之间稍停：one - three - eight。',
     reading:
         'Mia: What’s your phone number?\nShen: My number is five-zero-two.\nMia: Five-two-zero?\nShen: No. Five-zero-two.',
     readingQuestion: 'Shen 最后确认的号码是哪一个？',
@@ -1187,10 +1254,10 @@ const a0IndependentRequiredTerms = <String, List<List<String>>>{
     ['i like', 'i love'],
     ['do you like', '#question'],
   ],
-  // 完成姓名、地点、喜好和反问
+  // 请对方重复，完成姓名、喜好和反问
   'a0-10': [
+    ['say that again', 'speak slowly', 'pardon'],
     _introductionTerms,
-    ["i'm from", 'i am from', 'from + #word'],
     ['i like', 'i love'],
     ['#question'],
   ],
@@ -1690,19 +1757,19 @@ const a0Dialogues = <String, LessonDialogue>{
       'Say: Please say that again.',
       'Say: Please speak slowly.',
       'Now ask me your name or where I am from.',
-      'Say one thing you like.',
+      'Tell me what you like to drink.',
     ],
     hints: [
       'Please say that again.',
       'Please speak slowly.',
       'What’s your name?',
-      'I like tea.',
+      'I like water.',
     ],
     translations: [
       '请说：Please say that again（请再说一遍）。',
       '请说：Please speak slowly（请说慢一点）。',
       '现在请问我的名字或我来自哪里。',
-      '请说一件你喜欢的事物。',
+      '告诉我你喜欢喝什么。',
     ],
     requiredTerms: [
       ['say that again', 'again', 'pardon'],
@@ -1716,7 +1783,7 @@ const a0Dialogues = <String, LessonDialogue>{
       ],
       ['i like', 'i love'],
     ],
-    taskLabels: ['请求对方重复', '请求对方放慢语速', '反问名字或来自哪里', '说出一件你喜欢的事物'],
+    taskLabels: ['请求对方重复', '请求对方放慢语速', '反问名字或来自哪里', '说出你喜欢喝什么'],
   ),
 };
 

kouyu_english/lib/core/speech_compare.dart

@@ -0,0 +1,149 @@
+/// 把设备转写和示范句逐词对照。这不是发音评分：转写只说明“机器听成了什么”，
+/// 用来提示学习者哪些词没被听出来，值得再听示范、再说一次。
+class SpokenWord {
+  const SpokenWord(this.text, {required this.heard});
+
+  /// 示范句中的原词（保留大小写和标点，便于直接显示）。
+  final String text;
+  final bool heard;
+}
+
+class SpokenComparison {
+  const SpokenComparison({required this.words, required this.extraWords});
+
+  final List<SpokenWord> words;
+
+  /// 转写里出现、但示范句没有的词。
+  final List<String> extraWords;
+
+  int get heardCount => words.where((word) => word.heard).length;
+  int get total => words.length;
+  List<String> get missedWords => [
+    for (final word in words)
+      if (!word.heard) word.text,
+  ];
+
+  /// 全部听出且没有多余词。
+  bool get matches => total > 0 && heardCount == total && extraWords.isEmpty;
+
+  /// 大部分词被听出（≥ 80%）。
+  bool get close => total > 0 && heardCount / total >= 0.8;
+}
+
+const _digitWords = [
+  'zero',
+  'one',
+  'two',
+  'three',
+  'four',
+  'five',
+  'six',
+  'seven',
+  'eight',
+  'nine',
+];
+
+const _contractions = {
+  "i'm": ['i', 'am'],
+  "it's": ['it', 'is'],
+  "what's": ['what', 'is'],
+  "that's": ['that', 'is'],
+  "he's": ['he', 'is'],
+  "she's": ['she', 'is'],
+  "name's": ['name', 'is'],
+  "don't": ['do', 'not'],
+  "you're": ['you', 'are'],
+};
+
+/// 一个显示词对应的比较单位。例如 "I’m" 展开为 i/am，"138" 展开为
+/// one/three/eight，"o’clock" 统一为 oclock。
+List<String> _unitsOf(String raw) {
+  var word = raw
+      .toLowerCase()
+      .replaceAll(RegExp(r'[‘’`´]'), "'")
+      .replaceAll(RegExp(r"[^a-z0-9']"), '');
+  word = word.replaceAll(RegExp(r"^'+|'+$"), '');
+  if (word.isEmpty) return const [];
+  if (word == "o'clock") return const ['oclock'];
+  final expanded = _contractions[word];
+  if (expanded != null) return expanded;
+  if (RegExp(r'^\d+$').hasMatch(word)) {
+    return [for (final digit in word.split('')) _digitWords[int.parse(digit)]];
+  }
+  return [word.replaceAll("'", '')];
+}
+
+List<String> _displayWords(String text) => text
+    .replaceAll(RegExp(r'[-–—/]'), ' ')
+    .split(RegExp(r'\s+'))
+    .where((word) => _unitsOf(word).isNotEmpty)
+    .toList();
+
+List<String> _heardUnits(String transcript) => [
+  for (final word in _displayWords(transcript)) ..._unitsOf(word),
+];
+
+SpokenComparison compareSpoken(String expected, String transcript) {
+  final display = _displayWords(expected);
+  final expectedUnits = <String>[];
+  final owner = <int>[];
+  for (var index = 0; index < display.length; index++) {
+    for (final unit in _unitsOf(display[index])) {
+      expectedUnits.add(unit);
+      owner.add(index);
+    }
+  }
+  var heard = _heardUnits(transcript);
+  // 拼读时转写常把字母连成一个词（S H E N → Shen），拆回单个字母。
+  final spellsLetters =
+      expectedUnits.isNotEmpty &&
+      expectedUnits.every((unit) => RegExp(r'^[a-z]$').hasMatch(unit));
+  if (spellsLetters) {
+    heard = [for (final unit in heard) ...unit.split('')];
+  }
+
+  // 最长公共子序列：保持词序，重复词也能正确对齐。
+  final n = expectedUnits.length;
+  final m = heard.length;
+  final table = List.generate(n + 1, (_) => List.filled(m + 1, 0));
+  for (var i = n - 1; i >= 0; i--) {
+    for (var j = m - 1; j >= 0; j--) {
+      table[i][j] = expectedUnits[i] == heard[j]
+          ? table[i + 1][j + 1] + 1
+          : (table[i + 1][j] >= table[i][j + 1]
+                ? table[i + 1][j]
+                : table[i][j + 1]);
+    }
+  }
+  final unitHeard = List.filled(n, false);
+  final heardUsed = List.filled(m, false);
+  var i = 0;
+  var j = 0;
+  while (i < n && j < m) {
+    if (expectedUnits[i] == heard[j]) {
+      unitHeard[i] = true;
+      heardUsed[j] = true;
+      i++;
+      j++;
+    } else if (table[i + 1][j] >= table[i][j + 1]) {
+      i++;
+    } else {
+      j++;
+    }
+  }
+
+  final wordHeard = List.filled(display.length, true);
+  for (var unit = 0; unit < n; unit++) {
+    if (!unitHeard[unit]) wordHeard[owner[unit]] = false;
+  }
+  return SpokenComparison(
+    words: [
+      for (var index = 0; index < display.length; index++)
+        SpokenWord(display[index], heard: wordHeard[index]),
+    ],
+    extraWords: [
+      for (var index = 0; index < m; index++)
+        if (!heardUsed[index]) heard[index],
+    ],
+  );
+}

kouyu_english/lib/core/writing_feedback.dart

@@ -77,7 +77,8 @@ class WritingFeedback {
                   ]) ||
                   has('clock')),
         'a0-09' => hasIntroduction && has('like') && words.length >= 3,
-        'a0-10' => hasIntroduction && has('from') && has('like'),
+        'a0-10' =>
+          hasIntroduction && has('from') && has('like') && has('water'),
         _ => words.length >= 2,
       },
     };
@@ -113,7 +114,7 @@ class WritingFeedback {
     'a0-07' => '用 This is my … 介绍一位家人或朋友。',
     'a0-08' => '用 It’s … 写一个星期或整点时间。',
     'a0-09' => '用 I like … 写出一种喜好。',
-    'a0-10' => '分别写姓名、来自哪里和一项喜好三部分。',
+    'a0-10' => '分别写姓名、来自哪里和喜好三部分，喜好用 water：I like water.',
     _ => '再补充一个完整英文句子。',
   };
 }

kouyu_english/lib/features/assessment/assessment_page.dart

@@ -77,7 +77,7 @@ class _AssessmentPreparationPageState extends State<AssessmentPreparationPage> {
               '这些数字帮助你判断准备程度，但不会替代本次评估。',
             ),
           ),
-          const SectionCard(
+          SectionCard(
             tint: AppColors.warm,
             child: Text(
               '评估规则\n'

kouyu_english/lib/features/dialogue/dialogue_flow.dart

@@ -90,7 +90,7 @@ class _OpenScene extends StatelessWidget {
             ),
             Text(
               recommended ? 'A0 · 推荐' : 'A0',
-              style: const TextStyle(color: AppColors.green),
+              style: TextStyle(color: AppColors.green),
             ),
           ],
         ),
@@ -111,7 +111,7 @@ class _LockedScene extends StatelessWidget {
   Widget build(BuildContext context) => SectionCard(
     child: Row(
       children: [
-        const Icon(Icons.lock_outline, color: AppColors.muted),
+        Icon(Icons.lock_outline, color: AppColors.muted),
         const SizedBox(width: 10),
         Expanded(
           child: Column(
@@ -686,7 +686,7 @@ class _DialoguePageState extends State<DialoguePage>
                 tint: AppColors.warm,
                 child: Text(
                   hint!,
-                  style: const TextStyle(color: AppColors.warmInk),
+                  style: TextStyle(color: AppColors.warmInk),
                 ),
               ),
             if (aiNotice != null)
@@ -694,7 +694,7 @@ class _DialoguePageState extends State<DialoguePage>
                 tint: AppColors.warm,
                 child: Row(
                   children: [
-                    const Icon(
+                    Icon(
                       Icons.cloud_off_outlined,
                       size: 18,
                       color: AppColors.warmInk,
@@ -703,7 +703,7 @@ class _DialoguePageState extends State<DialoguePage>
                     Expanded(
                       child: Text(
                         aiNotice!,
-                        style: const TextStyle(
+                        style: TextStyle(
                           color: AppColors.warmInk,
                           fontSize: 13,
                         ),
@@ -715,7 +715,7 @@ class _DialoguePageState extends State<DialoguePage>
             if (validationError != null)
               Text(
                 validationError!,
-                style: const TextStyle(color: AppColors.warmInk),
+                style: TextStyle(color: AppColors.warmInk),
               ),
             TextField(
               controller: controller,
@@ -757,7 +757,7 @@ class _DialoguePageState extends State<DialoguePage>
                 transcriptEdited
                     ? '你修改了设备转写：这轮按文字作答保存。'
                     : '这是设备转写；未修改提交后会作为语音尝试保存。',
-                style: const TextStyle(color: AppColors.muted, fontSize: 12),
+                style: TextStyle(color: AppColors.muted, fontSize: 12),
               ),
             RecordingControls(
               recording: recording,
@@ -771,9 +771,9 @@ class _DialoguePageState extends State<DialoguePage>
               widget.state.keepRecordings
                   ? '录音只保存在本机，不会发送给 AI。'
                   : '录音仅供本次回听，离开后自动删除。',
-              style: const TextStyle(color: AppColors.muted, fontSize: 12),
+              style: TextStyle(color: AppColors.muted, fontSize: 12),
             ),
-            const Text(
+            Text(
               '文字输入可完成教学对话；即使使用语音输入，本受控教学对话也不会单独记为独立口语证据。',
               style: TextStyle(color: AppColors.muted, fontSize: 12),
             ),
@@ -792,7 +792,7 @@ class _DialoguePageState extends State<DialoguePage>
                 tint: AppColors.warm,
                 child: Text(
                   '下次可以注意：${latestFeedback!}',
-                  style: const TextStyle(color: AppColors.warmInk),
+                  style: TextStyle(color: AppColors.warmInk),
                 ),
               ),
             PrimaryButton(
@@ -916,7 +916,7 @@ class _TurnAction extends StatelessWidget {
         const SizedBox(width: 4),
         Text(
           label,
-          style: const TextStyle(
+          style: TextStyle(
             fontSize: 12,
             color: AppColors.green,
             fontWeight: FontWeight.w500,
@@ -935,7 +935,7 @@ class _AssistChip extends StatelessWidget {
   Widget build(BuildContext context) => ActionChip(
     label: Text(label),
     backgroundColor: AppColors.surface,
-    side: const BorderSide(color: AppColors.line),
+    side: BorderSide(color: AppColors.line),
     onPressed: onTap,
   );
 }

kouyu_english/lib/features/home/home_page.dart

@@ -62,7 +62,7 @@ class HomePage extends StatelessWidget {
           SectionCard(
             child: Row(
               children: [
-                const Icon(Icons.psychology_outlined, color: AppColors.green),
+                Icon(Icons.psychology_outlined, color: AppColors.green),
                 const SizedBox(width: 10),
                 Expanded(
                   child: Text(
@@ -92,7 +92,7 @@ class HomePage extends StatelessWidget {
                       isReview
                           ? '${(count * 2).clamp(2, 10)} 分钟'
                           : stageStep?.minutes ?? '12 分钟',
-                      style: const TextStyle(color: AppColors.green),
+                      style: TextStyle(color: AppColors.green),
                     ),
                   ],
                 ),
@@ -195,7 +195,7 @@ class _FrameworkNote extends StatelessWidget {
       color: AppColors.warm,
       borderRadius: BorderRadius.circular(14),
     ),
-    child: const Row(
+    child: Row(
       children: [
         Icon(Icons.info_outline, color: AppColors.warmInk),
         SizedBox(width: 8),

kouyu_english/lib/features/lesson/lesson_flow.dart

@@ -5,6 +5,7 @@ import '../../core/ai_service.dart';
 import '../../core/app_theme.dart';
 import '../../core/models.dart';
 import '../../core/seed_courses.dart';
+import '../../core/speech_compare.dart';
 import '../../core/voice_service.dart';
 import '../../core/writing_feedback.dart';
 import '../../widgets/app_widgets.dart';
@@ -112,6 +113,7 @@ class _LessonFlowState extends State<LessonFlow> {
           correctAnswer: activity.answers.first,
           selectedAnswer: selectedAnswer,
           audioPlayed: listeningAudioPlayed,
+          missed: listeningMissed,
           onSelected: (value) => setState(() {
             selectedAnswer = value;
             if (listeningOptions[value] != activity.answers.first) {
@@ -119,11 +121,14 @@ class _LessonFlowState extends State<LessonFlow> {
             }
           }),
           onPlayed: () => setState(() => listeningAudioPlayed = true),
-          onLookup: () => showLexiconLookup(
-            context,
-            state: widget.state,
-            initialText: activity.listening,
-          ),
+          onLookup: () {
+            setState(() => listeningMissed = true);
+            showLexiconLookup(
+              context,
+              state: widget.state,
+              initialText: activity.listening,
+            );
+          },
           onContinue:
               selectedAnswer >= 0 &&
                   listeningOptions[selectedAnswer] == activity.answers.first
@@ -135,6 +140,7 @@ class _LessonFlowState extends State<LessonFlow> {
         content = _SpeakingStep(
           state: widget.state,
           text: activity.speaking,
+          tip: activity.speakingTip,
           keepRecording: widget.state.keepRecordings,
           onContinue: widget.state.completeSpeaking,
         );

kouyu_english/lib/features/lesson/steps/independent_step.dart

@@ -190,7 +190,7 @@ class _IndependentStepState extends State<_IndependentStep>
             tint: AppColors.warm,
             child: Text(
               validationError!,
-              style: const TextStyle(color: AppColors.warmInk),
+              style: TextStyle(color: AppColors.warmInk),
             ),
           ),
         if (!widget.showHelp)

kouyu_english/lib/features/lesson/steps/listening_step.dart

@@ -8,6 +8,7 @@ class _ListeningStep extends StatelessWidget {
     required this.correctAnswer,
     required this.selectedAnswer,
     required this.audioPlayed,
+    required this.missed,
     required this.onSelected,
     required this.onPlayed,
     required this.onLookup,
@@ -21,6 +22,9 @@ class _ListeningStep extends StatelessWidget {
 
   final int selectedAnswer;
   final bool audioPlayed;
+
+  /// 选错过或查看过原文；此后可以看原文，但本题不再算独立听辨。
+  final bool missed;
   final ValueChanged<int> onSelected;
   final VoidCallback onPlayed;
   final VoidCallback onLookup;
@@ -29,6 +33,9 @@ class _ListeningStep extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final answers = options;
+    final answeredCorrectly =
+        selectedAnswer >= 0 && answers[selectedAnswer] == correctAnswer;
+    final revealText = answeredCorrectly || missed;
     return _LessonScaffold(
       step: 2,
       child: SpacedColumn(
@@ -47,22 +54,23 @@ class _ListeningStep extends StatelessWidget {
               onPlayed: onPlayed,
             ),
           ),
-          TextButton.icon(
-            onPressed: onLookup,
-            icon: const Icon(Icons.menu_book_outlined),
-            label: const Text('查看词或短语'),
-          ),
-          if (audioPlayed)
-            SectionCard(child: LexiconText(activity.listening, state: state)),
+          if (!audioPlayed)
+            Text(
+              '先播放音频，听完再选择。原文会在作答后显示。',
+              style: TextStyle(color: AppColors.muted),
+            ),
+          if (revealText)
+            SectionCard(child: LexiconText(activity.listening, state: state))
+          else if (audioPlayed)
+            TextButton.icon(
+              onPressed: onLookup,
+              icon: const Icon(Icons.menu_book_outlined),
+              label: const Text('听不懂，查看原文和词义（本题不计入听辨）'),
+            ),
           for (var index = 0; index < answers.length; index++)
             SectionCard(
               tint: selectedAnswer == index ? AppColors.softGreen : null,
-              onTap: () {
-                onSelected(index);
-                if (!audioPlayed) {
-                  onPlayed();
-                }
-              },
+              onTap: audioPlayed ? () => onSelected(index) : null,
               child: Row(
                 children: [
                   Icon(
@@ -74,18 +82,23 @@ class _ListeningStep extends StatelessWidget {
                         : AppColors.muted,
                   ),
                   const SizedBox(width: 10),
-                  Text(answers[index]),
+                  Text(
+                    answers[index],
+                    style: audioPlayed
+                        ? null
+                        : TextStyle(color: AppColors.muted),
+                  ),
                 ],
               ),
             ),
           PrimaryButton(
             label: selectedAnswer >= 0
                 ? '检查并继续'
-                : (audioPlayed ? '请选择答案' : '先播放音频或选择答案'),
+                : (audioPlayed ? '请选择答案' : '先播放音频'),
             onPressed: onContinue,
           ),
           if (selectedAnswer >= 0 && answers[selectedAnswer] != correctAnswer)
-            const Text(
+            Text(
               '再听一次，选择正确答案。',
               style: TextStyle(color: AppColors.warmInk),
             ),

kouyu_english/lib/features/lesson/steps/reading_step.dart

@@ -95,7 +95,7 @@ class _ReadingStepState extends State<_ReadingStep> {
                 Row(
                   mainAxisAlignment: MainAxisAlignment.spaceBetween,
                   children: [
-                    const Row(
+                    Row(
                       children: [
                         Icon(
                           Icons.chat_bubble_outline,
@@ -117,7 +117,7 @@ class _ReadingStepState extends State<_ReadingStep> {
                       onTap: () =>
                           VoiceService.instance.speak(widget.activity.reading),
                       borderRadius: BorderRadius.circular(16),
-                      child: const Padding(
+                      child: Padding(
                         padding: EdgeInsets.symmetric(
                           horizontal: 8,
                           vertical: 4,
@@ -194,7 +194,7 @@ class _ReadingStepState extends State<_ReadingStep> {
                     color: AppColors.green.withValues(alpha: 0.12),
                     borderRadius: BorderRadius.circular(6),
                   ),
-                  child: const Text(
+                  child: Text(
                     '问题',
                     style: TextStyle(
                       color: AppColors.green,
@@ -207,7 +207,7 @@ class _ReadingStepState extends State<_ReadingStep> {
                 Expanded(
                   child: Text(
                     widget.activity.readingQuestion,
-                    style: const TextStyle(
+                    style: TextStyle(
                       fontSize: 15,
                       fontWeight: FontWeight.w600,
                       color: AppColors.ink,
@@ -279,7 +279,7 @@ class _ReadingStepState extends State<_ReadingStep> {
                     color: AppColors.green.withValues(alpha: 0.3),
                   ),
                 ),
-                child: const Row(
+                child: Row(
                   children: [
                     Icon(Icons.check_circle, color: AppColors.green, size: 20),
                     SizedBox(width: 8),
@@ -309,7 +309,7 @@ class _ReadingStepState extends State<_ReadingStep> {
                     color: AppColors.warmInk.withValues(alpha: 0.2),
                   ),
                 ),
-                child: const Row(
+                child: Row(
                   children: [
                     Icon(
                       Icons.help_outline,
@@ -333,7 +333,7 @@ class _ReadingStepState extends State<_ReadingStep> {
             TextField(
               controller: controller,
               onChanged: (_) => setState(() {}),
-              decoration: const InputDecoration(
+              decoration: InputDecoration(
                 hintText: '用英文输入答案',
                 filled: true,
                 fillColor: AppColors.surface,
@@ -346,7 +346,7 @@ class _ReadingStepState extends State<_ReadingStep> {
               tint: AppColors.warm,
               child: Text(
                 '答案：${widget.activity.readingAnswer}',
-                style: const TextStyle(color: AppColors.warmInk),
+                style: TextStyle(color: AppColors.warmInk),
               ),
             ),
           if (!showAnswer &&

kouyu_english/lib/features/lesson/steps/speaking_step.dart

@@ -4,10 +4,12 @@ class _SpeakingStep extends StatefulWidget {
   const _SpeakingStep({
     required this.state,
     required this.text,
+    this.tip = '',
     required this.keepRecording,
     required this.onContinue,
   });
   final String text;
+  final String tip;
   final AppState state;
   final bool keepRecording;
   final VoidCallback onContinue;
@@ -78,21 +80,18 @@ class _SpeakingStepState extends State<_SpeakingStep>
           textAlign: TextAlign.center,
           style: const TextStyle(fontSize: 30, fontWeight: FontWeight.w600),
         ),
-        Text(
-          '/es - eɪtʃ - iː - en/',
-          style: Theme.of(context).textTheme.bodyMedium,
-        ),
         SectionCard(
           tint: AppColors.surfaceMuted,
           child: _AudioRow(label: '播放示范音', speech: widget.text),
         ),
-        const SectionCard(
-          tint: AppColors.warm,
-          child: Text(
-            '字母之间留一个短停顿。先清楚，不必快。',
-            style: TextStyle(color: AppColors.warmInk),
+        if (widget.tip.isNotEmpty)
+          SectionCard(
+            tint: AppColors.warm,
+            child: Text(
+              widget.tip,
+              style: TextStyle(color: AppColors.warmInk),
+            ),
           ),
-        ),
         SecondaryButton(
           label: transcribing
               ? '正在 AI 识别发音…'
@@ -137,9 +136,11 @@ class _SpeakingStepState extends State<_SpeakingStep>
             ),
           ),
         if (transcript.isNotEmpty)
-          SectionCard(child: Text("设备转写：$transcript\n请确认它是否接近你刚才说的内容。")),
+          _SpokenComparisonCard(expected: widget.text, transcript: transcript),
         const SectionCard(
-          child: Text('转写不确定或与原句不符时，可重说或继续文字练习；这一步只算跟读练习，不作为独立口语证据。'),
+          child: Text(
+            '转写只反映机器听成了什么，不等于发音评分；没听出的词可以再听示范、重说一次。这一步只算跟读练习，不作为独立口语证据。',
+          ),
         ),
         PrimaryButton(
           label: transcript.isEmpty ? '我已跟读，继续' : '确认并继续',
@@ -149,3 +150,54 @@ class _SpeakingStepState extends State<_SpeakingStep>
     ),
   );
 }
+
+class _SpokenComparisonCard extends StatelessWidget {
+  const _SpokenComparisonCard({
+    required this.expected,
+    required this.transcript,
+  });
+
+  final String expected;
+  final String transcript;
+
+  @override
+  Widget build(BuildContext context) {
+    final result = compareSpoken(expected, transcript);
+    final summary = result.matches
+        ? '每个词都被听出来了。'
+        : result.close
+        ? '大部分词都被听出来了，橙色的词再练一次。'
+        : '有几个词没被听出来：先听示范，再慢一点说。';
+    return SectionCard(
+      tint: result.close ? AppColors.softGreen : AppColors.warm,
+      child: SpacedColumn(
+        spacing: 8,
+        children: [
+          Text('听出 ${result.heardCount}/${result.total} 个词。$summary'),
+          Wrap(
+            spacing: 6,
+            runSpacing: 6,
+            children: [
+              for (final word in result.words)
+                Text(
+                  word.text,
+                  style: TextStyle(
+                    fontSize: 18,
+                    fontWeight: FontWeight.w600,
+                    color: word.heard ? AppColors.green : AppColors.warmInk,
+                    decoration: word.heard
+                        ? TextDecoration.none
+                        : TextDecoration.underline,
+                  ),
+                ),
+            ],
+          ),
+          Text(
+            '设备转写：$transcript',
+            style: Theme.of(context).textTheme.bodySmall,
+          ),
+        ],
+      ),
+    );
+  }
+}

kouyu_english/lib/features/lesson/steps/writing_step.dart

@@ -152,7 +152,7 @@ class _WritingStepState extends State<_WritingStep> {
                   Text('还可补充：${aiFeedback!.missing.join('、')}'),
                 if (aiFeedback!.suggestion != null)
                   Text('可参考改写：${aiFeedback!.suggestion}'),
-                const Text(
+                Text(
                   '这是学习帮助；请按自己的意思重写后再检查，系统不会仅凭 AI 建议记为掌握。',
                   style: TextStyle(fontSize: 12, color: AppColors.muted),
                 ),
@@ -164,7 +164,7 @@ class _WritingStepState extends State<_WritingStep> {
             tint: AppColors.warm,
             child: Text(
               aiFeedbackError!,
-              style: const TextStyle(color: AppColors.warmInk),
+              style: TextStyle(color: AppColors.warmInk),
             ),
           ),
         if (result != null)

kouyu_english/lib/features/onboarding/onboarding_pages.dart

@@ -45,7 +45,7 @@ class _WelcomePageState extends State<WelcomePage> {
                 ),
               ),
               const SizedBox(width: 12),
-              const Column(
+              Column(
                 crossAxisAlignment: CrossAxisAlignment.start,
                 children: [
                   Text(
@@ -312,7 +312,7 @@ class _PlacementPageState extends State<PlacementPage>
         label: '播放示范音',
         onPressed: () => VoiceService.instance.speak(_readAloudText),
       ),
-      const SectionCard(
+      SectionCard(
         tint: AppColors.surfaceMuted,
         child: Text('这一题只是开口热身，不录音、不打分，可以跳过。'),
       ),

kouyu_english/lib/features/progress/progress_pages.dart

@@ -130,14 +130,14 @@ class ProgressPage extends StatelessWidget {
                         ],
                       ),
                     ),
-                    const Icon(Icons.chevron_right, color: AppColors.muted),
+                    Icon(Icons.chevron_right, color: AppColors.muted),
                   ],
                 ),
               );
             },
           ),
           if (state.a0Passed)
-            const SectionCard(
+            SectionCard(
               tint: AppColors.softGreen,
               child: Text('A0 已通过。A1 主线内容尚未提供，可继续进行 A0 巩固。'),
             ),
@@ -311,6 +311,41 @@ class _SettingsPageState extends State<SettingsPage> {
           activeThumbColor: AppColors.green,
           onChanged: widget.state.toggleKeepRecordings,
         ),
+        Padding(
+          padding: const EdgeInsets.fromLTRB(4, 10, 4, 6),
+          child: Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              const Text(
+                '外观主题',
+                style: TextStyle(fontSize: 16, fontWeight: FontWeight.w600),
+              ),
+              const SizedBox(height: 4),
+              Text(
+                '深色模式适合夜间使用；跟随系统会随手机的深色开关自动切换',
+                style: TextStyle(fontSize: 12, color: AppColors.muted),
+              ),
+              const SizedBox(height: 10),
+              SizedBox(
+                width: double.infinity,
+                child: SegmentedButton<AppThemeMode>(
+                  segments: const [
+                    ButtonSegment(
+                      value: AppThemeMode.system,
+                      label: Text('跟随系统'),
+                    ),
+                    ButtonSegment(value: AppThemeMode.light, label: Text('浅色')),
+                    ButtonSegment(value: AppThemeMode.dark, label: Text('深色')),
+                  ],
+                  selected: {widget.state.themeMode},
+                  showSelectedIcon: false,
+                  onSelectionChanged: (selection) =>
+                      widget.state.setThemeMode(selection.first),
+                ),
+              ),
+            ],
+          ),
+        ),
         _SettingTile(
           title: '已保存的录音',
           subtitle: '回听或删除本机英语练习录音',
@@ -326,7 +361,7 @@ class _SettingsPageState extends State<SettingsPage> {
           '离线语音识别引擎',
           style: TextStyle(fontSize: 16, fontWeight: FontWeight.w600),
         ),
-        const Text(
+        Text(
           '已内置 SenseVoice-Small 高精度离线语音识别模型 (INT8)。随 App 安装包直接打包，离线即用，无需额外下载，零网络流量消耗。',
           style: TextStyle(fontSize: 12, color: AppColors.muted),
         ),
@@ -335,14 +370,14 @@ class _SettingsPageState extends State<SettingsPage> {
           subtitle: SherpaSttService.instance.isReady
               ? '已就绪 · 本地离线识别 (16kHz WAV · INT8)'
               : '预加载就绪 · 已内置打包',
-          trailing: const Icon(Icons.check_circle, color: AppColors.green, size: 20),
+          trailing: Icon(Icons.check_circle, color: AppColors.green, size: 20),
         ),
         const Divider(height: 28),
         const Text(
           '云同步与多端备份',
           style: TextStyle(fontSize: 16, fontWeight: FontWeight.w600),
         ),
-        const Text(
+        Text(
           '支持通过自建服务器在 Android / iOS / macOS 之间同步学习进度与复习掌握度。离线自动缓存，联网自动双向合并。',
           style: TextStyle(fontSize: 12, color: AppColors.muted),
         ),
@@ -363,7 +398,7 @@ class _SettingsPageState extends State<SettingsPage> {
           'AI 对话服务',
           style: TextStyle(fontSize: 16, fontWeight: FontWeight.w600),
         ),
-        const Text(
+        Text(
           '订阅版 ChatGPT / Gemini 不能直接作为 App API 使用。请使用自己的 API Key，或填写兼容 OpenAI 接口的 CLIProxyAPI 地址。密钥不在此页面保存。',
           style: TextStyle(fontSize: 12, color: AppColors.muted),
         ),
@@ -568,7 +603,7 @@ class _SettingsPageState extends State<SettingsPage> {
                   SectionCard(
                     child: Row(
                       children: [
-                        const Icon(Icons.mic_none, color: AppColors.green),
+                        Icon(Icons.mic_none, color: AppColors.green),
                         const SizedBox(width: 10),
                         Expanded(
                           child: Text(

kouyu_english/lib/features/progress/sync_settings_sheet.dart

@@ -201,7 +201,7 @@ class _SyncSettingsSheetState extends State<SyncSettingsSheet> {
                     ),
                 ],
               ),
-              const Text(
+              Text(
                 '本地优先架构：无网络时不影响学习，联网后自动双向合并学习进度与复习掌握度。',
                 style: TextStyle(fontSize: 13, color: AppColors.muted),
               ),
@@ -214,7 +214,7 @@ class _SyncSettingsSheetState extends State<SyncSettingsSheet> {
                                         children: [
                       Row(
                         children: [
-                          const CircleAvatar(
+                          CircleAvatar(
                             radius: 18,
                             backgroundColor: AppColors.softGreen,
                             child: Icon(Icons.person, color: AppColors.green),
@@ -232,7 +232,7 @@ class _SyncSettingsSheetState extends State<SyncSettingsSheet> {
                                 ),
                                 Text(
                                   _coordinator.serverUrl,
-                                  style: const TextStyle(
+                                  style: TextStyle(
                                     fontSize: 12,
                                     color: AppColors.muted,
                                   ),

kouyu_english/lib/features/review/review_page.dart

@@ -27,7 +27,8 @@ class ReviewPage extends StatefulWidget {
   State<ReviewPage> createState() => _ReviewPageState();
 }
 
-class _ReviewPageState extends State<ReviewPage> {
+class _ReviewPageState extends State<ReviewPage>
+    with VoiceAnswerMixin<ReviewPage> {
   final controller = TextEditingController();
   bool showHint = false;
   bool usedHelp = false;
@@ -35,29 +36,78 @@ class _ReviewPageState extends State<ReviewPage> {
   bool generatingVariant = false;
   bool generatingLesson = false;
 
+  /// The untouched transcript of a spoken answer; null for typed answers.
+  String? transcript;
+  bool dictationPlayed = false;
+
+  @override
+  AppState get voiceState => widget.state;
+
   @override
   void dispose() {
+    VoiceService.instance.stopSpeaking();
+    disposeVoiceAnswer(keepRecording: widget.state.keepRecordings);
     controller.dispose();
     super.dispose();
   }
 
+  void _resetAnswer() {
+    controller.clear();
+    // A recording still held here was never attached to evidence.
+    VoiceService.instance.deleteRecording(recordingPath);
+    showHint = false;
+    usedHelp = false;
+    validationMessage = null;
+    transcript = null;
+    recordingPath = null;
+    dictationPlayed = false;
+  }
+
   void _next(ReviewItem item, {required bool assisted}) {
     final result = ReviewFeedback.check(item, controller.text);
     if (!result.complete) {
       setState(() => validationMessage = result.message);
       return;
     }
+    final answer = controller.text.trim();
+    final spoken = transcript != null;
     widget.state.completeReview(
       item,
       assisted: assisted,
-      rawAnswer: controller.text.trim(),
+      rawAnswer: answer,
+      inputMode: spoken && transcript == answer ? 'speechToText' : 'text',
+      originalTranscript: transcript,
+      recordingPath: spoken && widget.state.keepRecordings
+          ? recordingPath
+          : null,
     );
-    controller.clear();
-    setState(() {
-      showHint = false;
-      usedHelp = false;
-      validationMessage = null;
-    });
+    // A kept recording now belongs to the evidence row; don't delete it.
+    if (spoken && widget.state.keepRecordings) recordingPath = null;
+    setState(_resetAnswer);
+  }
+
+  Future<void> _toggleVoice() async {
+    if (aiVoiceRecording) {
+      await finishVoiceInput(
+        keepAudio: widget.state.keepRecordings,
+        onTranscript: (text) {
+          controller.text = text;
+          transcript = text;
+          validationMessage = null;
+        },
+      );
+      return;
+    }
+    await VoiceService.instance.stopSpeaking();
+    await startVoiceInput(unavailableMessage: '无法访问麦克风，请检查录音权限。你仍可输入英文作答。');
+  }
+
+  Future<void> _play(String text, {bool slow = false}) async {
+    try {
+      await VoiceService.instance.speak(text, slow: slow);
+    } finally {
+      if (mounted) setState(() => dictationPlayed = true);
+    }
   }
 
   Future<void> _generateVariant(ReviewItem item) async {
@@ -144,6 +194,11 @@ class _ReviewPageState extends State<ReviewPage> {
         ),
       );
     }
+    final dictation = item.skill == dictationSkill
+        ? a0DictationSentences[item.id]
+        : null;
+    final spokenTask = item.skill == spokenRecallSkill;
+    final audioText = reviewAudioText(item.id, item.target);
     final checkpoint =
         widget.state.mastery[item.id]?.checkpoint ?? item.successfulReviews;
     final checkpointLabel = checkpoint >= 4
@@ -153,19 +208,22 @@ class _ReviewPageState extends State<ReviewPage> {
       child: SpacedColumn(
         children: [
           Eyebrow('今天复习 · ${widget.state.dueReviewCount} 项待完成'),
-          Text('不看答案，试着回答。', style: Theme.of(context).textTheme.headlineMedium),
+          Text(
+            dictation != null ? '听一听，写下来。' : '不看答案，试着回答。',
+            style: Theme.of(context).textTheme.headlineMedium,
+          ),
           Text(
             '目标技能：${item.skill}',
             style: Theme.of(context).textTheme.bodyMedium,
           ),
           Text(
             checkpointLabel,
-            style: const TextStyle(color: AppColors.green, fontSize: 13),
+            style: TextStyle(color: AppColors.green, fontSize: 13),
           ),
           if (item.isAiGenerated)
             Row(
               children: [
-                const Expanded(
+                Expanded(
                   child: Text(
                     'AI 生成题面 · 已通过客户端结构审核',
                     style: TextStyle(color: AppColors.muted, fontSize: 12),
@@ -174,12 +232,7 @@ class _ReviewPageState extends State<ReviewPage> {
                 TextButton(
                   onPressed: () {
                     widget.state.reportGeneratedReviewVariant(item);
-                    controller.clear();
-                    setState(() {
-                      showHint = false;
-                      usedHelp = false;
-                      validationMessage = null;
-                    });
+                    setState(_resetAnswer);
                     ScaffoldMessenger.of(context).showSnackBar(
                       const SnackBar(content: Text('已隔离该 AI 题面，并换回本地审核题。')),
                     );
@@ -192,7 +245,7 @@ class _ReviewPageState extends State<ReviewPage> {
             tint: AppColors.softGreen,
             child: SpacedColumn(
               children: [
-                const Text(
+                Text(
                   '情境',
                   style: TextStyle(
                     color: AppColors.green,
@@ -200,6 +253,22 @@ class _ReviewPageState extends State<ReviewPage> {
                   ),
                 ),
                 Text(item.prompt, style: const TextStyle(fontSize: 19)),
+                if (dictation != null)
+                  Row(
+                    children: [
+                      IconButton.filled(
+                        tooltip: '播放',
+                        onPressed: () => _play(dictation.sentence),
+                        icon: const Icon(Icons.play_arrow),
+                      ),
+                      const SizedBox(width: 10),
+                      Expanded(child: Text(dictationPlayed ? '再听一次' : '播放句子')),
+                      TextButton(
+                        onPressed: () => _play(dictation.sentence, slow: true),
+                        child: const Text('慢速'),
+                      ),
+                    ],
+                  ),
               ],
             ),
           ),
@@ -207,14 +276,34 @@ class _ReviewPageState extends State<ReviewPage> {
             controller: controller,
             minLines: 2,
             maxLines: 4,
+            enabled: dictation == null || dictationPlayed,
             onChanged: (_) => setState(() {}),
-            decoration: const InputDecoration(
-              hintText: '输入你会怎么回答',
+            decoration: InputDecoration(
+              hintText: dictation != null
+                  ? (dictationPlayed ? '写下你听到的英文' : '先播放句子')
+                  : (spokenTask ? '点下方麦克风说出来，或输入英文' : '输入你会怎么回答'),
               filled: true,
               fillColor: AppColors.surface,
-              border: OutlineInputBorder(),
+              border: const OutlineInputBorder(),
             ),
           ),
+          if (dictation == null)
+            OutlinedButton.icon(
+              onPressed: transcribing ? null : _toggleVoice,
+              icon: Icon(listening ? Icons.stop : Icons.mic_none),
+              label: Text(
+                transcribing
+                    ? '正在识别…'
+                    : listening
+                    ? '说完了，停止并识别'
+                    : '用语音回答',
+              ),
+            ),
+          if (transcript != null && controller.text.trim() != transcript)
+            Text(
+              '你修改了语音转写，本次按文字作答记录。',
+              style: TextStyle(fontSize: 12, color: AppColors.muted),
+            ),
           Wrap(
             spacing: 8,
             runSpacing: 8,
@@ -231,19 +320,14 @@ class _ReviewPageState extends State<ReviewPage> {
                 label: const Text('稍后复习'),
                 onPressed: () {
                   widget.state.postponeReview(item);
-                  setState(() {});
+                  setState(_resetAnswer);
                 },
               ),
               ActionChip(
                 label: const Text('暂时想不起来'),
                 onPressed: () {
                   widget.state.reportReviewFailure(item);
-                  controller.clear();
-                  setState(() {
-                    showHint = false;
-                    usedHelp = false;
-                    validationMessage = null;
-                  });
+                  setState(_resetAnswer);
                 },
               ),
               ActionChip(
@@ -262,25 +346,36 @@ class _ReviewPageState extends State<ReviewPage> {
               ActionChip(
                 avatar: const Icon(Icons.search, size: 16),
                 label: const Text('查词查句'),
-                onPressed: () => showLexiconLookup(
-                  context,
-                  state: widget.state,
-                ),
+                onPressed: () =>
+                    showLexiconLookup(context, state: widget.state),
               ),
             ],
           ),
           if (showHint)
             SectionCard(
               tint: AppColors.warm,
-              child: Text(
-                '参考：${item.hint}\n目标：${item.target}',
-                style: const TextStyle(color: AppColors.warmInk),
+              child: SpacedColumn(
+                spacing: 8,
+                children: [
+                  Text(
+                    dictation != null
+                        ? '句子意思：${item.hint}\n目标词句：${item.target}'
+                        : '参考：${item.hint}\n目标：${item.target}',
+                    style: TextStyle(color: AppColors.warmInk),
+                  ),
+                  if (audioText != null && dictation == null)
+                    TextButton.icon(
+                      onPressed: () => _play(audioText),
+                      icon: const Icon(Icons.volume_up_outlined),
+                      label: Text('听示范：$audioText'),
+                    ),
+                ],
               ),
             ),
           if (validationMessage != null)
             Text(
               validationMessage!,
-              style: const TextStyle(color: AppColors.warmInk),
+              style: TextStyle(color: AppColors.warmInk),
             ),
           PrimaryButton(
             label: usedHelp ? '带提示完成' : '我能独立回答',
@@ -288,7 +383,7 @@ class _ReviewPageState extends State<ReviewPage> {
                 ? null
                 : () => _next(item, assisted: usedHelp),
           ),
-          const Text(
+          Text(
             '提示后完成会在明天换题复练；第一次想不起来先复核，连续两次才会降低当前检查点。',
             style: TextStyle(fontSize: 12, color: AppColors.muted),
           ),
@@ -439,9 +534,7 @@ class _AdaptiveLessonPageState extends State<AdaptiveLessonPage>
       );
       return;
     }
-    await startVoiceInput(
-      unavailableMessage: '无法访问麦克风，请检查录音权限。你仍可输入英文完成补练。',
-    );
+    await startVoiceInput(unavailableMessage: '无法访问麦克风，请检查录音权限。你仍可输入英文完成补练。');
   }
 
   @override
@@ -508,7 +601,7 @@ class _AdaptiveLessonPageState extends State<AdaptiveLessonPage>
             Text(
               '审核：${widget.state.cachedAdaptiveLessonAuditor ?? '已配置服务'} · '
               '${_formatAuditTime(widget.state.cachedAdaptiveLessonAuditedAt!)}',
-              style: const TextStyle(color: AppColors.muted, fontSize: 12),
+              style: TextStyle(color: AppColors.muted, fontSize: 12),
             ),
           Text(task.prompt, style: Theme.of(context).textTheme.headlineMedium),
           if (showStimulus)
@@ -517,7 +610,7 @@ class _AdaptiveLessonPageState extends State<AdaptiveLessonPage>
               child: Text(task.stimulus, style: const TextStyle(fontSize: 20)),
             )
           else
-            const SectionCard(
+            SectionCard(
               tint: AppColors.surfaceMuted,
               child: Text('先播放音频，再输入你听到的答案。'),
             ),
@@ -579,9 +672,7 @@ class _AdaptiveLessonPageState extends State<AdaptiveLessonPage>
                         child: CircularProgressIndicator(strokeWidth: 2),
                       )
                     : Icon(
-                        listening
-                            ? Icons.stop_circle_outlined
-                            : Icons.mic_none,
+                        listening ? Icons.stop_circle_outlined : Icons.mic_none,
                         color: listening ? AppColors.green : null,
                       ),
               ),
@@ -639,7 +730,7 @@ class _AdaptiveLessonPageState extends State<AdaptiveLessonPage>
           if (answerFeedback != null)
             Text(
               answerFeedback!,
-              style: const TextStyle(color: AppColors.warmInk),
+              style: TextStyle(color: AppColors.warmInk),
             ),
           if (showReference)
             SectionCard(

kouyu_english/lib/features/shell/learning_shell.dart

@@ -121,6 +121,11 @@ class _LearningShellState extends State<LearningShell> {
     switch (route) {
       case _ShellRoute.lesson:
         body = LessonFlow(
+          // 换课或换段时重建，避免上一段的听力选择和播放状态沿用过来。
+          key: ValueKey(
+            '${widget.state.activeLessonId}-'
+            '${widget.state.activeSegmentIndexFor(widget.state.activeLessonId)}',
+          ),
           state: widget.state,
           onOpenDialogue: () => showDialogue(inLesson: true),
           onFinish: () => showTab(tab),
@@ -333,7 +338,7 @@ class _LearningMap extends StatelessWidget {
                 children: [
                   Text(
                     "复习已有积压，今天先完成 ${state.dueReviewCount} 项到期复习，再开启新课。",
-                    style: const TextStyle(color: AppColors.warmInk),
+                    style: TextStyle(color: AppColors.warmInk),
                   ),
                   SecondaryButton(label: "先去复习", onPressed: onOpenReview),
                 ],

kouyu_english/lib/main.dart

@@ -47,43 +47,60 @@ class _KouyuEnglishAppState extends State<KouyuEnglishApp> {
     super.dispose();
   }
 
+  static ThemeMode _themeMode(AppThemeMode mode) => switch (mode) {
+    AppThemeMode.system => ThemeMode.system,
+    AppThemeMode.light => ThemeMode.light,
+    AppThemeMode.dark => ThemeMode.dark,
+  };
+
   @override
   Widget build(BuildContext context) {
-    return MaterialApp(
-      title: '芽说英语 · SpeakSprout',
-      debugShowCheckedModeBanner: false,
-      theme: buildAppTheme(),
-      home: AnimatedBuilder(
-        animation: appState,
-        builder: (context, _) {
-          if (!appState.isLoaded) {
-            return const Scaffold(
-              body: Center(child: CircularProgressIndicator()),
-            );
-          }
-          if (appState.onboardingComplete) {
-            return LearningShell(state: appState);
-          }
-          if (onboardingStep == 0) {
-            return WelcomePage(
-              state: appState,
-              onContinue: () => setState(() => onboardingStep = 1),
-            );
-          }
-          return PopScope(
-            canPop: false,
-            onPopInvokedWithResult: (didPop, _) {
-              if (!didPop) {
-                setState(() => onboardingStep = 0);
-              }
-            },
-            child: PlacementPage(
-              state: appState,
-              onBack: () => setState(() => onboardingStep = 0),
-              onStart: () => appState.finishOnboarding(),
-            ),
-          );
+    return AnimatedBuilder(
+      animation: appState,
+      builder: (context, _) => MaterialApp(
+        title: '芽说英语 · SpeakSprout',
+        debugShowCheckedModeBanner: false,
+        theme: buildAppTheme(Brightness.light),
+        darkTheme: buildAppTheme(Brightness.dark),
+        themeMode: _themeMode(appState.themeMode),
+        // Mirror the resolved brightness into the global palette that many
+        // widgets read directly, so it tracks both the user's choice and any
+        // system dark-mode change.
+        builder: (context, child) {
+          AppColors.applyBrightness(Theme.of(context).brightness);
+          return child ?? const SizedBox.shrink();
         },
+        home: Builder(
+          builder: (context) {
+            if (!appState.isLoaded) {
+              return const Scaffold(
+                body: Center(child: CircularProgressIndicator()),
+              );
+            }
+            if (appState.onboardingComplete) {
+              return LearningShell(state: appState);
+            }
+            if (onboardingStep == 0) {
+              return WelcomePage(
+                state: appState,
+                onContinue: () => setState(() => onboardingStep = 1),
+              );
+            }
+            return PopScope(
+              canPop: false,
+              onPopInvokedWithResult: (didPop, _) {
+                if (!didPop) {
+                  setState(() => onboardingStep = 0);
+                }
+              },
+              child: PlacementPage(
+                state: appState,
+                onBack: () => setState(() => onboardingStep = 0),
+                onStart: () => appState.finishOnboarding(),
+              ),
+            );
+          },
+        ),
       ),
     );
   }

kouyu_english/lib/widgets/app_widgets.dart

@@ -120,7 +120,7 @@ class SecondaryButton extends StatelessWidget {
         onPressed: onPressed,
         style: OutlinedButton.styleFrom(
           foregroundColor: AppColors.ink,
-          side: const BorderSide(color: AppColors.line),
+          side: BorderSide(color: AppColors.line),
           shape: RoundedRectangleBorder(
             borderRadius: BorderRadius.circular(14),
           ),
@@ -139,7 +139,7 @@ class Eyebrow extends StatelessWidget {
   @override
   Widget build(BuildContext context) => Text(
     text,
-    style: const TextStyle(
+    style: TextStyle(
       color: AppColors.green,
       fontWeight: FontWeight.w600,
       fontSize: 13,

kouyu_english/lib/widgets/lexicon_lookup.dart

@@ -165,7 +165,7 @@ class _LexiconTextState extends State<LexiconText> {
           TextSpan(
             text: matched,
             recognizer: recognizer,
-            style: const TextStyle(
+            style: TextStyle(
               color: AppColors.green,
               decoration: TextDecoration.underline,
               decorationColor: AppColors.green,
@@ -401,7 +401,7 @@ class _LexiconLookupSheetState extends State<_LexiconLookupSheet> {
           child: SpacedColumn(
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
-              const Row(
+              Row(
                 children: [
                   Icon(Icons.translate, size: 16, color: AppColors.green),
                   SizedBox(width: 6),
@@ -464,7 +464,7 @@ class _LexiconLookupSheetState extends State<_LexiconLookupSheet> {
                 if (analysis.pronunciationTips != null &&
                     analysis.pronunciationTips!.isNotEmpty) ...[
                   const SizedBox(height: 6),
-                  const Row(
+                  Row(
                     children: [
                       Icon(
                         Icons.record_voice_over_outlined,
@@ -522,7 +522,7 @@ class _LexiconLookupSheetState extends State<_LexiconLookupSheet> {
           const SizedBox(height: 4),
           Row(
             children: [
-              const Icon(
+              Icon(
                 Icons.auto_stories_outlined,
                 size: 18,
                 color: AppColors.green,
@@ -560,7 +560,7 @@ class _LexiconLookupSheetState extends State<_LexiconLookupSheet> {
                             if (phrase.ipa != null && phrase.ipa!.isNotEmpty)
                               Text(
                                 phrase.ipa!,
-                                style: const TextStyle(
+                                style: TextStyle(
                                   fontSize: 13,
                                   color: AppColors.muted,
                                 ),
@@ -575,7 +575,7 @@ class _LexiconLookupSheetState extends State<_LexiconLookupSheet> {
                       ),
                       const SizedBox(width: 4),
                       _addedToReview.contains(phrase.phrase.toLowerCase())
-                          ? const Chip(
+                          ? Chip(
                               label: Text('已在复习', style: TextStyle(fontSize: 12)),
                               avatar: Icon(Icons.check, size: 14, color: AppColors.green),
                               padding: EdgeInsets.zero,
@@ -602,7 +602,7 @@ class _LexiconLookupSheetState extends State<_LexiconLookupSheet> {
                   if (phrase.usageNote != null && phrase.usageNote!.isNotEmpty)
                     Text(
                       '用法：${phrase.usageNote}',
-                      style: const TextStyle(
+                      style: TextStyle(
                         fontSize: 12,
                         color: AppColors.muted,
                       ),
@@ -618,7 +618,7 @@ class _LexiconLookupSheetState extends State<_LexiconLookupSheet> {
           children: [
             Text(
               '解析引擎：${analysis.provider} · 本机已缓存',
-              style: const TextStyle(fontSize: 12, color: AppColors.muted),
+              style: TextStyle(fontSize: 12, color: AppColors.muted),
             ),
             TextButton.icon(
               onPressed: requestingSentenceAnalysis ? null : _requestSentenceAnalysis,
@@ -666,7 +666,7 @@ class _LexiconLookupSheetState extends State<_LexiconLookupSheet> {
                         color: AppColors.softGreen,
                         borderRadius: BorderRadius.circular(10),
                       ),
-                      child: const Text(
+                      child: Text(
                         '已解析',
                         style: TextStyle(
                           fontSize: 11,
@@ -769,7 +769,7 @@ class _LexiconLookupSheetState extends State<_LexiconLookupSheet> {
                 const SizedBox(height: 4),
                 Row(
                   children: [
-                    const Icon(Icons.layers_outlined, size: 18, color: AppColors.green),
+                    Icon(Icons.layers_outlined, size: 18, color: AppColors.green),
                     const SizedBox(width: 6),
                     Text(
                       '本地词典匹配到的短语 (${localPhrases.length})',
@@ -804,7 +804,7 @@ class _LexiconLookupSheetState extends State<_LexiconLookupSheet> {
                             ),
                             const SizedBox(width: 4),
                             _addedToReview.contains(phraseItem.word.toLowerCase())
-                                ? const Icon(Icons.check, size: 18, color: AppColors.green)
+                                ? Icon(Icons.check, size: 18, color: AppColors.green)
                                 : OutlinedButton(
                                     style: OutlinedButton.styleFrom(
                                       visualDensity: VisualDensity.compact,
@@ -823,7 +823,7 @@ class _LexiconLookupSheetState extends State<_LexiconLookupSheet> {
                         if (phraseItem.example.isNotEmpty)
                           Text(
                             '例：${phraseItem.example} (${phraseItem.exampleMeaning})',
-                            style: const TextStyle(
+                            style: TextStyle(
                               fontSize: 12,
                               color: AppColors.muted,
                             ),
@@ -865,7 +865,7 @@ class _LexiconLookupSheetState extends State<_LexiconLookupSheet> {
                       if (sentenceAnalysisError != null)
                         Text(
                           sentenceAnalysisError!,
-                          style: const TextStyle(color: AppColors.warmInk),
+                          style: TextStyle(color: AppColors.warmInk),
                         ),
                     ],
                   ),
@@ -888,7 +888,7 @@ class _LexiconLookupSheetState extends State<_LexiconLookupSheet> {
                 if (temporaryError != null)
                   Text(
                     temporaryError!,
-                    style: const TextStyle(color: AppColors.warmInk),
+                    style: TextStyle(color: AppColors.warmInk),
                   ),
 
                 if (temporaryDefinition != null)