flagging

packages/practice_engine/lib/logic/deck_service.dart

@@ -25,6 +25,20 @@ class DeckService {
     return deck.copyWith(questions: updatedQuestions);
   }
 
+  /// Toggles the flagged state of a question.
+  static Deck toggleQuestionFlag({
+    required Deck deck,
+    required String questionId,
+  }) {
+    final updatedQuestions = deck.questions.map((q) {
+      if (q.id == questionId) {
+        return q.copyWith(isFlagged: !q.isFlagged);
+      }
+      return q;
+    }).toList();
+    return deck.copyWith(questions: updatedQuestions);
+  }
+
   /// Marks a question as needs practice (manual override).
   ///
   /// Sets isKnown to false and streak to 0, but keeps priority unchanged.

packages/practice_engine/lib/models/deck.dart

@@ -70,6 +70,12 @@ class Deck {
   /// Number of questions marked as known.
   int get knownCount => questions.where((q) => q.isKnown).length;
 
+  /// Number of questions the user has flagged.
+  int get flaggedCount => questions.where((q) => q.isFlagged).length;
+
+  /// Questions that the user has flagged.
+  List<Question> get flaggedQuestions => questions.where((q) => q.isFlagged).toList();
+
   /// Practice percentage: (known / total) * 100
   double get practicePercentage {
     if (questions.isEmpty) return 0.0;

packages/practice_engine/lib/models/question.dart

@@ -24,6 +24,9 @@ class Question {
   /// Whether this question is considered "known".
   final bool isKnown;
 
+  /// Whether the user has flagged this question for review.
+  final bool isFlagged;
+
   /// Priority points (higher = more likely to be selected).
   final int priorityPoints;
 
@@ -44,6 +47,7 @@ class Question {
     @Deprecated('Use correctAnswerIndices instead') int? correctAnswerIndex,
     this.consecutiveCorrect = 0,
     this.isKnown = false,
+    this.isFlagged = false,
     this.priorityPoints = 0,
     this.lastAttemptIndex = -1,
     this.totalCorrectAttempts = 0,
@@ -61,6 +65,7 @@ class Question {
     @Deprecated('Use correctAnswerIndices instead') int? correctAnswerIndex,
     int? consecutiveCorrect,
     bool? isKnown,
+    bool? isFlagged,
     int? priorityPoints,
     int? lastAttemptIndex,
     int? totalCorrectAttempts,
@@ -74,6 +79,7 @@ class Question {
       correctAnswerIndex: correctAnswerIndex ?? this.correctAnswerIndex,
       consecutiveCorrect: consecutiveCorrect ?? this.consecutiveCorrect,
       isKnown: isKnown ?? this.isKnown,
+      isFlagged: isFlagged ?? this.isFlagged,
       priorityPoints: priorityPoints ?? this.priorityPoints,
       lastAttemptIndex: lastAttemptIndex ?? this.lastAttemptIndex,
       totalCorrectAttempts: totalCorrectAttempts ?? this.totalCorrectAttempts,
@@ -117,6 +123,7 @@ class Question {
           correctAnswerIndices.toString() == other.correctAnswerIndices.toString() &&
           consecutiveCorrect == other.consecutiveCorrect &&
           isKnown == other.isKnown &&
+          isFlagged == other.isFlagged &&
           priorityPoints == other.priorityPoints &&
           lastAttemptIndex == other.lastAttemptIndex &&
           totalCorrectAttempts == other.totalCorrectAttempts &&
@@ -130,6 +137,7 @@ class Question {
       correctAnswerIndices.hashCode ^
       consecutiveCorrect.hashCode ^
       isKnown.hashCode ^
+      isFlagged.hashCode ^
       priorityPoints.hashCode ^
       lastAttemptIndex.hashCode ^
       totalCorrectAttempts.hashCode ^