feat: 完善听力口语辅助状态记录、练习分块与复习抽查间隔机制

kouyu_english/lib/core/app_state.dart

@@ -53,12 +53,19 @@ abstract class _AppStateData extends ChangeNotifier {
   LessonStep lessonStep = LessonStep.preview;
   int previewIndex = 0;
   bool lessonListeningComplete = false;
+  bool listeningAudioPlayed = false;
+  bool listeningAudioUnavailable = false;
+  ListeningSupport listeningSupport = ListeningSupport.none;
+  int listeningAttempts = 0;
+  bool sentenceBuildUsed = false;
+  int sentenceBuildIndex = 0;
   bool lessonSpeakingComplete = false;
   bool lessonReadingComplete = false;
   bool lessonWritingComplete = false;
   bool lessonDialogueComplete = false;
   bool independentAttemptComplete = false;
   bool independentAttemptAssisted = false;
+  bool independentAttemptPending = false;
   bool independentAttemptSpoken = false;
   String lessonWritingDraft = '';
   String independentAttemptDraft = '';
@@ -101,7 +108,8 @@ abstract class _AppStateData extends ChangeNotifier {
 }
 
 class AppState extends _AppStateData
-    with _ReviewAndMastery,
+    with
+        _ReviewAndMastery,
         _ReceptiveWords,
         _AssessmentProgress,
         _LessonProgress,
@@ -245,10 +253,14 @@ class AppState extends _AppStateData
     notifyListeners();
   }
 
-  /// Applies the placement result. The start may land on any loaded lesson
-  /// across A0–B1, and placement never counts as passing a lesson.
+  /// Placement never marks an earlier lesson as passed or opens draft content.
   void setPlacementStartLesson(String lessonId) {
-    if (!allLessons.any((lesson) => lesson.id == lessonId)) return;
+    if (!allLessons.any(
+      (lesson) =>
+          lesson.id == lessonId && lesson.status == ContentStatus.approved,
+    )) {
+      return;
+    }
     placementStartLessonId = lessonId;
     activeLessonId = lessonId;
     _resetLessonFlow();
@@ -312,12 +324,19 @@ class AppState extends _AppStateData
     lessonStep = LessonStep.preview;
     previewIndex = 0;
     lessonListeningComplete = false;
+    listeningAudioPlayed = false;
+    listeningAudioUnavailable = false;
+    listeningSupport = ListeningSupport.none;
+    listeningAttempts = 0;
+    sentenceBuildUsed = false;
+    sentenceBuildIndex = 0;
     lessonSpeakingComplete = false;
     lessonReadingComplete = false;
     lessonWritingComplete = false;
     lessonDialogueComplete = false;
     independentAttemptComplete = false;
     independentAttemptAssisted = false;
+    independentAttemptPending = false;
     independentAttemptSpoken = false;
     mastery.clear();
     notifyListeners();