no chart

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)
-    final displayAttempts = attempts.reversed.take(maxDisplayItems).toList();
+    // Get recent attempts (take most recent, then reverse so oldest is first for chronological display)
+    final displayAttempts = attempts.reversed.take(maxDisplayItems).toList().reversed.toList();
     if (displayAttempts.isEmpty) {
       return const SizedBox.shrink();
     }
 
-    // Find min and max values for scaling
-    final percentages = displayAttempts.map((e) => e.percentageCorrect).toList();
+    // Find min and max values for scaling (using unknown percentage)
+    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);