no chart

lib/data/default_deck.dart

@@ -156,42 +156,43 @@ class DefaultDeck {
     final now = DateTime.now();
     
     // Create mock attempt history (4 previous attempts)
+    // Unknown percentage decreases over time as more questions become known
     final attemptHistory = [
-      // First attempt - 6/10 correct (60%)
+      // First attempt - 6/10 correct (60%), ~85% unknown (17/20 questions)
       AttemptHistoryEntry(
         timestamp: now.subtract(const Duration(days: 7)).millisecondsSinceEpoch,
         totalQuestions: 10,
-        correctAnswers: 6,
+        correctCount: 6,
-        incorrectAnswers: 4,
+        percentageCorrect: 60.0,
-        skippedAnswers: 0,
+        timeSpent: 245000, // milliseconds
-        timeSpentSeconds: 245,
+        unknownPercentage: 85.0, // 17 out of 20 questions unknown
       ),
-      // Second attempt - 7/10 correct (70%)
+      // Second attempt - 7/10 correct (70%), ~70% unknown (14/20 questions)
       AttemptHistoryEntry(
         timestamp: now.subtract(const Duration(days: 5)).millisecondsSinceEpoch,
         totalQuestions: 10,
-        correctAnswers: 7,
+        correctCount: 7,
-        incorrectAnswers: 3,
+        percentageCorrect: 70.0,
-        skippedAnswers: 0,
+        timeSpent: 198000, // milliseconds
-        timeSpentSeconds: 198,
+        unknownPercentage: 70.0, // 14 out of 20 questions unknown
       ),
-      // Third attempt - 8/10 correct (80%)
+      // Third attempt - 8/10 correct (80%), ~55% unknown (11/20 questions)
       AttemptHistoryEntry(
         timestamp: now.subtract(const Duration(days: 3)).millisecondsSinceEpoch,
         totalQuestions: 10,
-        correctAnswers: 8,
+        correctCount: 8,
-        incorrectAnswers: 2,
+        percentageCorrect: 80.0,
-        skippedAnswers: 0,
+        timeSpent: 187000, // milliseconds
-        timeSpentSeconds: 187,
+        unknownPercentage: 55.0, // 11 out of 20 questions unknown
       ),
-      // Fourth attempt - 9/10 correct (90%)
+      // Fourth attempt - 9/10 correct (90%), ~45% unknown (9/20 questions)
       AttemptHistoryEntry(
         timestamp: now.subtract(const Duration(days: 1)).millisecondsSinceEpoch,
         totalQuestions: 10,
-        correctAnswers: 9,
+        correctCount: 9,
-        incorrectAnswers: 1,
+        percentageCorrect: 90.0,
-        skippedAnswers: 0,
+        timeSpent: 165000, // milliseconds
-        timeSpentSeconds: 165,
+        unknownPercentage: 45.0, // 9 out of 20 questions unknown
       ),
     ];
 

lib/main.dart

@@ -3,7 +3,10 @@ import 'routes.dart';
 import 'theme.dart';
 import 'services/deck_storage.dart';
 
-void main() {
+void main() async {
+  // Ensure Flutter bindings are initialized before using any plugins
+  WidgetsFlutterBinding.ensureInitialized();
+  
   // Initialize storage early
   DeckStorage().initialize();
   runApp(const DeckyApp());

lib/screens/attempt_screen.dart

@@ -477,6 +477,8 @@ class _AttemptScreenState extends State<AttemptScreen> {
     // Add attempt to history
     final historyEntry = AttemptHistoryEntry.fromAttemptResult(
       result: result.result,
+      totalQuestionsInDeck: result.updatedDeck.numberOfQuestions,
+      knownCount: result.updatedDeck.knownCount,
       timestamp: endTime,
     );
     final updatedDeckWithHistory = result.updatedDeck.copyWith(

lib/screens/deck_list_screen.dart

@@ -193,7 +193,7 @@ class _DeckListScreenState extends State<DeckListScreen> {
   void _useDefaultDeck() async {
     // Check if default deck already exists
     final baseDeck = DefaultDeck.deck;
-    final deckExists = _deckStorage.hasDeckSync(baseDeck.id);
+    final deckExists = await _deckStorage.hasDeck(baseDeck.id);
     
     // Show dialog to ask if user wants mock data (only if deck doesn't exist)
     bool? includeMockData = false;
@@ -214,36 +214,47 @@ class _DeckListScreenState extends State<DeckListScreen> {
         ? DefaultDeck.deckWithMockData 
         : DefaultDeck.deck;
     
-    if (deckExists) {
+    try {
-      // If it exists, create a copy with a new ID
+      if (deckExists) {
-      final clonedDeck = defaultDeck.copyWith(
+        // If it exists, create a copy with a new ID
-        id: '${defaultDeck.id}_${DateTime.now().millisecondsSinceEpoch}',
+        final clonedDeck = defaultDeck.copyWith(
-      );
+          id: '${defaultDeck.id}_${DateTime.now().millisecondsSinceEpoch}',
-      _deckStorage.saveDeckSync(clonedDeck);
-      
-      if (mounted) {
-        ScaffoldMessenger.of(context).showSnackBar(
-          const SnackBar(
-            content: Text('Default deck added successfully'),
-            backgroundColor: Colors.green,
-          ),
         );
-      }
+        await _deckStorage.saveDeck(clonedDeck);
-    } else {
-      // Save default deck to storage
-      _deckStorage.saveDeckSync(defaultDeck);
         
+        if (mounted) {
+          ScaffoldMessenger.of(context).showSnackBar(
+            const SnackBar(
+              content: Text('Default deck added successfully'),
+              backgroundColor: Colors.green,
+            ),
+          );
+        }
+      } else {
+        // Save default deck to storage
+        await _deckStorage.saveDeck(defaultDeck);
+        
+        if (mounted) {
+          ScaffoldMessenger.of(context).showSnackBar(
+            const SnackBar(
+              content: Text('Default deck added successfully'),
+              backgroundColor: Colors.green,
+            ),
+          );
+        }
+      }
+      
+      _loadDecks();
+    } catch (e) {
       if (mounted) {
         ScaffoldMessenger.of(context).showSnackBar(
-          const SnackBar(
+          SnackBar(
-            content: Text('Default deck added successfully'),
+            content: Text('Error adding deck: $e'),
-            backgroundColor: Colors.green,
+            backgroundColor: Colors.red,
           ),
         );
       }
     }
-    
-    _loadDecks();
   }
 
   @override

lib/screens/deck_overview_screen.dart

@@ -2,7 +2,6 @@ import 'package:flutter/material.dart';
 import 'package:practice_engine/practice_engine.dart';
 import '../routes.dart';
 import '../services/deck_storage.dart';
-import '../widgets/attempts_chart.dart';
 
 class DeckOverviewScreen extends StatefulWidget {
   const DeckOverviewScreen({super.key});
@@ -283,6 +282,105 @@ class _DeckOverviewScreenState extends State<DeckOverviewScreen> {
     }
   }
 
+  Widget _buildProgressStats(BuildContext context) {
+    if (_deck == null) return const SizedBox.shrink();
+    
+    final totalQuestions = _deck!.numberOfQuestions;
+    final knownCount = _deck!.knownCount;
+    final unknownCount = totalQuestions - knownCount;
+    final unknownPercentage = totalQuestions > 0 
+        ? (unknownCount / totalQuestions * 100.0) 
+        : 0.0;
+    final knownPercentage = totalQuestions > 0 
+        ? (knownCount / totalQuestions * 100.0) 
+        : 0.0;
+    
+    // Get progress trend if we have history
+    // Attempt history is stored chronologically (oldest first), so first is oldest, last is newest
+    String? trendText;
+    if (_deck!.attemptHistory.isNotEmpty) {
+      final oldestAttempt = _deck!.attemptHistory.first;
+      final newestAttempt = _deck!.attemptHistory.last;
+      final oldestUnknown = oldestAttempt.unknownPercentage;
+      final newestUnknown = newestAttempt.unknownPercentage;
+      final improvement = oldestUnknown - newestUnknown;
+      
+      if (improvement > 0) {
+        trendText = 'Improved by ${improvement.toStringAsFixed(1)}% since first attempt';
+      } else if (improvement < 0) {
+        trendText = '${improvement.abs().toStringAsFixed(1)}% more to learn since first attempt';
+      } else {
+        trendText = 'No change since first attempt';
+      }
+    }
+    
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: [
+        // Main stat: Unknown percentage
+        Row(
+          mainAxisAlignment: MainAxisAlignment.spaceBetween,
+          children: [
+            Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                Text(
+                  'Questions to Learn',
+                  style: Theme.of(context).textTheme.bodyMedium?.copyWith(
+                        color: Theme.of(context).colorScheme.onSurface.withValues(alpha: 0.7),
+                      ),
+                ),
+                const SizedBox(height: 4),
+                Text(
+                  '${unknownPercentage.toStringAsFixed(1)}%',
+                  style: Theme.of(context).textTheme.headlineMedium?.copyWith(
+                        fontWeight: FontWeight.bold,
+                        color: Theme.of(context).colorScheme.primary,
+                      ),
+                ),
+                Text(
+                  '$unknownCount of $totalQuestions questions',
+                  style: Theme.of(context).textTheme.bodySmall,
+                ),
+              ],
+            ),
+            Column(
+              crossAxisAlignment: CrossAxisAlignment.end,
+              children: [
+                Text(
+                  'Questions Known',
+                  style: Theme.of(context).textTheme.bodyMedium?.copyWith(
+                        color: Theme.of(context).colorScheme.onSurface.withValues(alpha: 0.7),
+                      ),
+                ),
+                const SizedBox(height: 4),
+                Text(
+                  '${knownPercentage.toStringAsFixed(1)}%',
+                  style: Theme.of(context).textTheme.headlineMedium?.copyWith(
+                        fontWeight: FontWeight.bold,
+                        color: Theme.of(context).colorScheme.secondary,
+                      ),
+                ),
+                Text(
+                  '$knownCount of $totalQuestions questions',
+                  style: Theme.of(context).textTheme.bodySmall,
+                ),
+              ],
+            ),
+          ],
+        ),
+        if (trendText != null) ...[
+          const SizedBox(height: 12),
+          Text(
+            trendText,
+            style: Theme.of(context).textTheme.bodySmall?.copyWith(
+                  color: Theme.of(context).colorScheme.onSurface.withValues(alpha: 0.6),
+                ),
+          ),
+        ],
+      ],
+    );
+  }
 
   @override
   Widget build(BuildContext context) {
@@ -462,15 +560,12 @@ class _DeckOverviewScreenState extends State<DeckOverviewScreen> {
                       const Divider(),
                       const SizedBox(height: 8),
                       Text(
-                        'Progress Chart',
+                        'Learning Progress',
                         style: Theme.of(context).textTheme.titleSmall,
                       ),
-                      const SizedBox(height: 8),
+                      const SizedBox(height: 12),
-                      // Progress chart
+                      // Current progress
-                      AttemptsChart(
+                      _buildProgressStats(context),
-                        attempts: _deck!.attemptHistory,
-                        maxDisplayItems: 15,
-                      ),
                     ],
                   ],
                 ),

lib/services/deck_storage.dart

@@ -14,17 +14,25 @@ class DeckStorage {
   static const String _deckIdsKey = 'deck_ids';
   bool _initialized = false;
   SharedPreferences? _prefs;
-  final Future<void> _initFuture;
+  Future<void>? _initFuture;
 
-  DeckStorage._internal() : _initFuture = SharedPreferences.getInstance().then((prefs) {
+  DeckStorage._internal();
-    _instance._prefs = prefs;
+
-    _instance._initialized = true;
+  /// Lazy initialization of SharedPreferences
-  });
+  Future<void> _initSharedPreferences() async {
+    if (_initFuture == null) {
+      _initFuture = SharedPreferences.getInstance().then((prefs) {
+        _instance._prefs = prefs;
+        _instance._initialized = true;
+      });
+    }
+    await _initFuture;
+  }
 
   /// Initialize storage with default deck if empty
   Future<void> initialize() async {
     if (_initialized) return;
-    await _initFuture;
+    await _initSharedPreferences();
     
     // Load existing decks
     final deckIds = _prefs!.getStringList(_deckIdsKey) ?? [];
@@ -39,7 +47,7 @@ class DeckStorage {
   /// Ensure storage is initialized
   Future<void> _ensureInitialized() async {
     if (!_initialized) {
-      await _initFuture;
+      await _initSharedPreferences();
       await initialize();
     }
   }
@@ -75,10 +83,10 @@ class DeckStorage {
       'attemptHistory': deck.attemptHistory.map((entry) => {
         'timestamp': entry.timestamp,
         'totalQuestions': entry.totalQuestions,
-        'correctAnswers': entry.correctAnswers,
+        'correctCount': entry.correctCount,
-        'incorrectAnswers': entry.incorrectAnswers,
+        'percentageCorrect': entry.percentageCorrect,
-        'skippedAnswers': entry.skippedAnswers,
+        'timeSpent': entry.timeSpent,
-        'timeSpentSeconds': entry.timeSpentSeconds,
+        'unknownPercentage': entry.unknownPercentage,
       }).toList(),
       'incompleteAttempt': deck.incompleteAttempt != null ? {
         'attemptId': deck.incompleteAttempt!.attemptId,
@@ -145,13 +153,23 @@ class DeckStorage {
     final historyJson = json['attemptHistory'] as List<dynamic>? ?? [];
     final attemptHistory = historyJson.map((entryJson) {
       final entryMap = entryJson as Map<String, dynamic>;
+      // Support both old and new field names for backward compatibility
+      final correctCount = entryMap['correctCount'] as int? ?? 
+                          entryMap['correctAnswers'] as int? ?? 0;
+      final totalQuestions = entryMap['totalQuestions'] as int? ?? 0;
+      final timeSpent = entryMap['timeSpent'] as int? ?? 
+                       (entryMap['timeSpentSeconds'] as int? ?? 0) * 1000; // Convert seconds to milliseconds
+      // Calculate percentageCorrect if not present
+      final percentageCorrect = entryMap['percentageCorrect'] as double? ?? 
+                               (totalQuestions > 0 ? (correctCount / totalQuestions * 100) : 0.0);
+      final unknownPercentage = entryMap['unknownPercentage'] as double? ?? 0.0;
       return AttemptHistoryEntry(
         timestamp: entryMap['timestamp'] as int? ?? 0,
-        totalQuestions: entryMap['totalQuestions'] as int? ?? 0,
+        totalQuestions: totalQuestions,
-        correctAnswers: entryMap['correctAnswers'] as int? ?? 0,
+        correctCount: correctCount,
-        incorrectAnswers: entryMap['incorrectAnswers'] as int? ?? 0,
+        percentageCorrect: percentageCorrect,
-        skippedAnswers: entryMap['skippedAnswers'] as int? ?? 0,
+        timeSpent: timeSpent,
-        timeSpentSeconds: entryMap['timeSpentSeconds'] as int?,
+        unknownPercentage: unknownPercentage,
       );
     }).toList();
 

lib/widgets/attempts_chart.dart

@@ -1,7 +1,9 @@
 import 'package:flutter/material.dart';
 import 'package:practice_engine/practice_engine.dart';
 
-/// A chart widget that visualizes attempt progress over time.
+/// A chart widget that visualizes learning progress over time.
+/// Shows the percentage of questions that are still unknown (not yet learned).
+/// As you learn more questions, this percentage decreases.
 class AttemptsChart extends StatelessWidget {
   final List<AttemptHistoryEntry> attempts;
   final int maxDisplayItems;
@@ -18,14 +20,14 @@ class AttemptsChart extends StatelessWidget {
       return const SizedBox.shrink();
     }
 
-    // Get recent attempts (most recent first, then reverse for display)
+    // Get recent attempts (take most recent, then reverse so oldest is first for chronological display)
-    final displayAttempts = attempts.reversed.take(maxDisplayItems).toList();
+    final displayAttempts = attempts.reversed.take(maxDisplayItems).toList().reversed.toList();
     if (displayAttempts.isEmpty) {
       return const SizedBox.shrink();
     }
 
-    // Find min and max values for scaling
+    // Find min and max values for scaling (using unknown percentage)
-    final percentages = displayAttempts.map((e) => e.percentageCorrect).toList();
+    final percentages = displayAttempts.map((e) => e.unknownPercentage).toList();
     final minValue = percentages.reduce((a, b) => a < b ? a : b);
     final maxValue = percentages.reduce((a, b) => a > b ? a : b);
     final range = (maxValue - minValue).clamp(10.0, 100.0); // Ensure minimum range
@@ -148,7 +150,7 @@ class _AttemptsChartPainter extends CustomPainter {
     final points = <Offset>[];
 
     for (int i = 0; i < attempts.length; i++) {
-      final percentage = attempts[i].percentageCorrect;
+      final percentage = attempts[i].unknownPercentage;
       final normalizedValue = chartRange > 0 
           ? ((percentage - chartMin) / chartRange).clamp(0.0, 1.0)
           : 0.5; // If all values are the same, center vertically
@@ -201,7 +203,7 @@ class _AttemptsChartPainter extends CustomPainter {
     }
 
     // Draw average line (dashed)
-    final avgPercentage = attempts.map((e) => e.percentageCorrect).reduce((a, b) => a + b) / attempts.length;
+    final avgPercentage = attempts.map((e) => e.unknownPercentage).reduce((a, b) => a + b) / attempts.length;
     final avgNormalized = ((avgPercentage - chartMin) / chartRange).clamp(0.0, 1.0);
     final avgY = padding + chartHeight - (avgNormalized * chartHeight);
     

pubspec.lock

@@ -57,6 +57,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.3.3"
+  ffi:
+    dependency: transitive
+    description:
+      name: ffi
+      sha256: "289279317b4b16eb2bb7e271abccd4bf84ec9bdcbe999e278a94b804f5630418"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.4"
+  file:
+    dependency: transitive
+    description:
+      name: file
+      sha256: a3b4f84adafef897088c160faf7dfffb7696046cb13ae90b508c2cbc95d3b8d4
+      url: "https://pub.dev"
+    source: hosted
+    version: "7.0.1"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -75,6 +91,11 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  flutter_web_plugins:
+    dependency: transitive
+    description: flutter
+    source: sdk
+    version: "0.0.0"
   leak_tracker:
     dependency: transitive
     description:
@@ -139,6 +160,46 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.9.1"
+  path_provider_linux:
+    dependency: transitive
+    description:
+      name: path_provider_linux
+      sha256: f7a1fe3a634fe7734c8d3f2766ad746ae2a2884abe22e241a8b301bf5cac3279
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.2.1"
+  path_provider_platform_interface:
+    dependency: transitive
+    description:
+      name: path_provider_platform_interface
+      sha256: "88f5779f72ba699763fa3a3b06aa4bf6de76c8e5de842cf6f29e2e06476c2334"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.2"
+  path_provider_windows:
+    dependency: transitive
+    description:
+      name: path_provider_windows
+      sha256: bd6f00dbd873bfb70d0761682da2b3a2c2fccc2b9e84c495821639601d81afe7
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.0"
+  platform:
+    dependency: transitive
+    description:
+      name: platform
+      sha256: "5d6b1b0036a5f331ebc77c850ebc8506cbc1e9416c27e59b439f917a902a4984"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.6"
+  plugin_platform_interface:
+    dependency: transitive
+    description:
+      name: plugin_platform_interface
+      sha256: "4820fbfdb9478b1ebae27888254d445073732dae3d6ea81f0b7e06d5dedc3f02"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.8"
   practice_engine:
     dependency: "direct main"
     description:
@@ -146,6 +207,62 @@ packages:
       relative: true
     source: path
     version: "1.0.0"
+  shared_preferences:
+    dependency: "direct main"
+    description:
+      name: shared_preferences
+      sha256: "2939ae520c9024cb197fc20dee269cd8cdbf564c8b5746374ec6cacdc5169e64"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.5.4"
+  shared_preferences_android:
+    dependency: transitive
+    description:
+      name: shared_preferences_android
+      sha256: "83af5c682796c0f7719c2bbf74792d113e40ae97981b8f266fa84574573556bc"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.18"
+  shared_preferences_foundation:
+    dependency: transitive
+    description:
+      name: shared_preferences_foundation
+      sha256: "4e7eaffc2b17ba398759f1151415869a34771ba11ebbccd1b0145472a619a64f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.5.6"
+  shared_preferences_linux:
+    dependency: transitive
+    description:
+      name: shared_preferences_linux
+      sha256: "580abfd40f415611503cae30adf626e6656dfb2f0cee8f465ece7b6defb40f2f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.1"
+  shared_preferences_platform_interface:
+    dependency: transitive
+    description:
+      name: shared_preferences_platform_interface
+      sha256: "57cbf196c486bc2cf1f02b85784932c6094376284b3ad5779d1b1c6c6a816b80"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.1"
+  shared_preferences_web:
+    dependency: transitive
+    description:
+      name: shared_preferences_web
+      sha256: c49bd060261c9a3f0ff445892695d6212ff603ef3115edbb448509d407600019
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.3"
+  shared_preferences_windows:
+    dependency: transitive
+    description:
+      name: shared_preferences_windows
+      sha256: "94ef0f72b2d71bc3e700e025db3710911bd51a71cefb65cc609dd0d9a982e3c1"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.1"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -215,6 +332,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "15.0.2"
+  web:
+    dependency: transitive
+    description:
+      name: web
+      sha256: "868d88a33d8a87b18ffc05f9f030ba328ffefba92d6c127917a2ba740f9cfe4a"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.1"
+  xdg_directories:
+    dependency: transitive
+    description:
+      name: xdg_directories
+      sha256: "7a3f37b05d989967cdddcbb571f1ea834867ae2faa29725fd085180e0883aa15"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.0"
 sdks:
-  dart: ">=3.8.0-0 <4.0.0"
+  dart: ">=3.9.0 <4.0.0"
-  flutter: ">=3.18.0-18.0.pre.54"
+  flutter: ">=3.35.0"