Fix habit streak counter to require full daily completion of targetGoal

src/storage.ts

@@ -326,16 +326,53 @@ export class StorageManager {
             timestamp: new Date().toISOString()
         });
 
-        // Update habit streak
+        // Update habit streak based on fully-completed consecutive days
         const habit = data.habits.find(h => h.id === habitId);
         if (habit) {
             habit.lastCompletedDate = dateStr;
-            habit.streak = (habit.streak || 0) + 1;
+            habit.streak = this.calculateHabitStreak(habitId, habit.targetGoal, data.dailyHabitLogs);
         }
 
         this.saveData(data);
     }
 
+    calculateHabitStreak(habitId: string, targetGoal: number, logs: HabitLog[]): number {
+        // Count completions per date for this habit
+        const habitLogs = logs.filter(l => l.habitId === habitId);
+        const countsByDate: Record<string, number> = {};
+        for (const log of habitLogs) {
+            countsByDate[log.date] = (countsByDate[log.date] || 0) + 1;
+        }
+
+        // Get dates where fully completed (>= targetGoal), sorted most recent first
+        const completedDates = Object.keys(countsByDate)
+            .filter(date => countsByDate[date] >= targetGoal)
+            .sort()
+            .reverse();
+
+        if (completedDates.length === 0) return 0;
+
+        // Count consecutive days going backward from the most recent fully-completed day
+        let streak = 1;
+        let currentDate = completedDates[0];
+
+        for (let i = 1; i < completedDates.length; i++) {
+            const [year, month, day] = currentDate.split('-').map(Number);
+            const prevDay = new Date(year, month - 1, day);
+            prevDay.setDate(prevDay.getDate() - 1);
+            const expectedDate = this.formatDate(prevDay);
+
+            if (completedDates[i] === expectedDate) {
+                streak++;
+                currentDate = completedDates[i];
+            } else {
+                break;
+            }
+        }
+
+        return streak;
+    }
+
     isHabitCompletedToday(habitId: string): boolean {
         const data = this.getData();
         const todayStr = this.formatDate(new Date());

tests/storage.test.ts

@@ -164,13 +164,66 @@ describe('StorageManager', () => {
             expect(storage.getHabits().length).toBe(0);
         });
 
-        it('should log habit completion and increment streak', () => {
+        it('should log habit completion and set streak to 1 when targetGoal met', () => {
             const habit = storage.addHabit({ name: 'Exercise' });
             storage.logHabitCompletion(habit.id, new Date());
             const updated = storage.getHabits().find(h => h.id === habit.id);
             expect(updated?.streak).toBe(1);
         });
 
+        it('should not increment streak when targetGoal is not yet met', () => {
+            const habit = storage.addHabit({ name: 'Drink Water', targetGoal: 10 });
+            storage.logHabitCompletion(habit.id, new Date());
+            storage.logHabitCompletion(habit.id, new Date());
+            const updated = storage.getHabits().find(h => h.id === habit.id);
+            expect(updated?.streak).toBe(0);
+        });
+
+        it('should set streak to 1 when targetGoal is fully met', () => {
+            const habit = storage.addHabit({ name: 'Drink Water', targetGoal: 3 });
+            storage.logHabitCompletion(habit.id, new Date());
+            storage.logHabitCompletion(habit.id, new Date());
+            storage.logHabitCompletion(habit.id, new Date());
+            const updated = storage.getHabits().find(h => h.id === habit.id);
+            expect(updated?.streak).toBe(1);
+        });
+
+        it('should count consecutive fully-completed days as streak', () => {
+            const habit = storage.addHabit({ name: 'Exercise' });
+            const day1 = new Date(2025, 0, 13);
+            const day2 = new Date(2025, 0, 14);
+            const day3 = new Date(2025, 0, 15);
+            storage.logHabitCompletion(habit.id, day1);
+            storage.logHabitCompletion(habit.id, day2);
+            storage.logHabitCompletion(habit.id, day3);
+            const updated = storage.getHabits().find(h => h.id === habit.id);
+            expect(updated?.streak).toBe(3);
+        });
+
+        it('should reset streak count when there is a gap between completed days', () => {
+            const habit = storage.addHabit({ name: 'Exercise' });
+            const day1 = new Date(2025, 0, 13);
+            const day3 = new Date(2025, 0, 15);
+            storage.logHabitCompletion(habit.id, day1);
+            storage.logHabitCompletion(habit.id, day3);
+            const updated = storage.getHabits().find(h => h.id === habit.id);
+            expect(updated?.streak).toBe(1);
+        });
+
+        it('should extend streak when retroactively completing a missed day', () => {
+            const habit = storage.addHabit({ name: 'Exercise' });
+            const day1 = new Date(2025, 0, 13);
+            const day2 = new Date(2025, 0, 14);
+            const day3 = new Date(2025, 0, 15);
+            storage.logHabitCompletion(habit.id, day1);
+            storage.logHabitCompletion(habit.id, day3);
+            // Streak is 1 (gap at day2)
+            storage.logHabitCompletion(habit.id, day2);
+            // Now day1, day2, day3 are all complete → streak = 3
+            const updated = storage.getHabits().find(h => h.id === habit.id);
+            expect(updated?.streak).toBe(3);
+        });
+
         it('should count habit completions for today', () => {
             const habit = storage.addHabit({ name: 'Push-ups', targetGoal: 3 });
             storage.logHabitCompletion(habit.id, new Date());
@@ -193,6 +246,19 @@ describe('StorageManager', () => {
             expect(storage.countHabitCompletionsForDate(habit.id, '2025-01-15')).toBe(2);
             expect(storage.countHabitCompletionsForDate(habit.id, '2025-01-16')).toBe(0);
         });
+
+        it('should calculate streak correctly using calculateHabitStreak', () => {
+            const habit = storage.addHabit({ name: 'Drink Water', targetGoal: 2 });
+            const day1 = new Date(2025, 0, 13);
+            const day2 = new Date(2025, 0, 14);
+            storage.logHabitCompletion(habit.id, day1);
+            storage.logHabitCompletion(habit.id, day1);
+            storage.logHabitCompletion(habit.id, day2);
+            storage.logHabitCompletion(habit.id, day2);
+            const data = storage.getData();
+            const streak = storage.calculateHabitStreak(habit.id, habit.targetGoal, data.dailyHabitLogs);
+            expect(streak).toBe(2);
+        });
     });
 
     // ========================