diff --git a/src/hooks/__tests__/useGamificationCoverage.test.tsx b/src/hooks/__tests__/useGamificationCoverage.test.tsx
new file mode 100644
index 0000000..54eb54f
--- /dev/null
+++ b/src/hooks/__tests__/useGamificationCoverage.test.tsx
@@ -0,0 +1,234 @@
+/* eslint-disable @typescript-eslint/no-explicit-any */
+import { renderHook, act, waitFor } from '@testing-library/react';
+import { useGamification } from '../useGamification';
+import { useAuth } from '../useAuth';
+import { saveGamificationData, getGamification } from '../../firebase/firestore';
+import { vi, describe, it, expect, beforeEach } from 'vitest';
+import type { UserData } from '../../types/question';
+
+// Hoist the mock function
+const { mockGenerateDaily } = vi.hoisted(() => {
+    return { mockGenerateDaily: vi.fn().mockReturnValue([]) };
+});
+
+// Mock dependencies
+vi.mock('../useAuth');
+vi.mock('../../firebase/firestore');
+vi.mock('../../data/gamificationData', async (importOriginal) => {
+    const actual = await importOriginal<typeof import('../../data/gamificationData')>();
+    return {
+        ...actual,
+        generateDailyMissions: mockGenerateDaily,
+    };
+});
+
+// Helper for mock data
+const getFullMockData = (overrides: any = {}) => ({
+    level: { level: 1, currentXP: 0, totalXP: 0 },
+    streak: { currentStreak: 5, longestStreak: 10, lastActivityDate: '', activityHistory: [] },
+    achievements: [],
+    activeMissions: [],
+    inventory: {
+        ownedItems: ['item1'],
+        equippedAvatar: 'avatar1',
+        equippedFrame: 'frame1',
+        equippedTitle: 'title1'
+    },
+    powerUps: {
+        inventory: { skip: 0, fifty_fifty: 0, extra_hint: 0, double_stars: 0, shield: 0 },
+        usesToday: { skip: 0, fifty_fifty: 0, extra_hint: 0, double_stars: 0, shield: 0 },
+        lastResetDate: '2025-01-01'
+    },
+    stats: {
+        totalQuestionsCompleted: 0,
+        totalCorrectAnswers: 0,
+        consecutiveCorrect: 0,
+        bestConsecutiveCorrect: 0,
+        weekendQuestionsCount: 0,
+        lastWeekendDate: '',
+        totalPlayTime: 0,
+        worldsCompleted: 0,
+        perfectWorlds: 0,
+        completedWorldIds: []
+    },
+    ...overrides
+});
+
+describe('useGamification Coverage Edge Cases', () => {
+    const mockUser = { uid: 'test-user-coverage', displayName: 'Coverage User' };
+    const mockUserData: Partial<UserData> = {
+        uid: 'test-user-coverage',
+        balance: 100,
+    };
+    const mockUpdateUserData = vi.fn();
+
+    beforeEach(() => {
+        vi.clearAllMocks();
+        mockGenerateDaily.mockReturnValue([]);
+
+        (useAuth as any).mockReturnValue({
+            user: mockUser,
+            userData: mockUserData,
+            updateUserData: mockUpdateUserData,
+            isGuest: false
+        });
+
+        (saveGamificationData as any).mockResolvedValue(undefined);
+    });
+
+    afterEach(() => {
+        vi.useRealTimers();
+    });
+
+    it('should migrate legacy streak data from UserData if present and greater than current', async () => {
+        // Set date to match lastActiveDate so streak is preserved but not incremented
+        // Only fake Date so setTimeout/setInterval (used by waitFor) still work
+        vi.useFakeTimers({ toFake: ['Date'] });
+        vi.setSystemTime(new Date('2025-01-01T12:00:00Z'));
+
+        // Mock legacy user data having better streak
+        (useAuth as any).mockReturnValue({
+            user: mockUser,
+            userData: { ...mockUserData, streak: 50, longestStreak: 100, lastActiveDate: '2025-01-01' },
+            updateUserData: mockUpdateUserData,
+            isGuest: false
+        });
+
+        // Mock current gamification having worse streak
+        (getGamification as any).mockResolvedValue(getFullMockData({
+             streak: { currentStreak: 5, longestStreak: 10, lastActivityDate: '' }
+        }));
+
+        const { result } = renderHook(() => useGamification());
+        await waitFor(() => expect(result.current.loading).toBe(false));
+
+        // Expect migration to have happened
+        expect(result.current.streak.currentStreak).toBe(50);
+        expect(result.current.streak.longestStreak).toBe(100);
+        // Expect save to be called
+        expect(saveGamificationData).toHaveBeenCalledWith(
+            mockUser.uid,
+            expect.objectContaining({
+                streak: expect.objectContaining({ currentStreak: 50 })
+            })
+        );
+    });
+
+    it('should unlock world_champion achievement after completing 5 worlds', async () => {
+         (getGamification as any).mockResolvedValue(getFullMockData({
+             stats: { worldsCompleted: 4, completedWorldIds: ['1','2','3','4'] }
+        }));
+
+        const { result } = renderHook(() => useGamification());
+        await waitFor(() => expect(result.current.loading).toBe(false));
+
+        await act(async () => {
+            // Completing 5th world
+            result.current.checkWorldAchievements('world-5', 10, 10, 5);
+        });
+
+        await waitFor(() => {
+             expect(result.current.unlockedAchievements.some(a => a.id === 'world_champion')).toBe(true);
+        });
+    });
+
+    it('should dismiss level up modal', async () => {
+        (getGamification as any).mockResolvedValue(getFullMockData());
+        const { result } = renderHook(() => useGamification());
+        await waitFor(() => expect(result.current.loading).toBe(false));
+
+        // Trigger level up
+        await act(async () => {
+             result.current.recordQuestionCompleted(true, 5000, 10);
+        });
+        expect(result.current.showLevelUp).not.toBeNull();
+
+        // Dismiss
+        await act(async () => {
+            result.current.dismissLevelUp();
+        });
+        expect(result.current.showLevelUp).toBeNull();
+    });
+
+    it('should dismiss mission notification', async () => {
+         // Setup mission completion scenario
+         const today = new Date().toISOString().split('T')[0];
+         const missionId = `daily_${today}_test`;
+         const mockMission = {
+                missionId,
+                id: missionId,
+                title: 'Test Mission',
+                type: 'daily',
+                objectiveType: 'complete_questions',
+                targetValue: 1,
+                target: 1,
+                progress: 0,
+                status: 'active',
+                rewards: { stars: 50, xp: 200 },
+                starsReward: 50,
+                xpReward: 200,
+         };
+         mockGenerateDaily.mockReturnValue([mockMission]);
+         (getGamification as any).mockResolvedValue(getFullMockData({ activeMissions: [] }));
+
+         const { result } = renderHook(() => useGamification());
+         await waitFor(() => expect(result.current.loading).toBe(false));
+
+         // Trigger completion
+         await act(async () => {
+              result.current.recordQuestionCompleted(true, 10, 0, { starsEarned: 5 });
+         });
+
+         await waitFor(() => {
+             expect(result.current.missionNotification).not.toBeNull();
+         });
+
+         // Dismiss
+         await act(async () => {
+             result.current.dismissMissionNotification();
+         });
+         expect(result.current.missionNotification).toBeNull();
+    });
+
+    it('should mark achievement as seen', async () => {
+        // Setup initial state with an achievement
+         (getGamification as any).mockResolvedValue(getFullMockData({
+             achievements: [{ achievementId: 'first_world', unlockedAt: '2025-01-01', seen: false }]
+        }));
+
+        const { result } = renderHook(() => useGamification());
+        await waitFor(() => expect(result.current.loading).toBe(false));
+
+        await act(async () => {
+            result.current.markAchievementSeen('first_world');
+        });
+
+        // Verify save
+         expect(saveGamificationData).toHaveBeenCalledWith(
+            mockUser.uid,
+            expect.objectContaining({
+                achievements: expect.arrayContaining([
+                    expect.objectContaining({ achievementId: 'first_world', seen: true })
+                ])
+            })
+        );
+    });
+
+    it('should not add duplicate achievements via safeAddAchievement', async () => {
+         // Start with unlocked achievement
+         (getGamification as any).mockResolvedValue(getFullMockData({
+             achievements: [{ achievementId: 'first_world', unlockedAt: '2025-01-01', seen: true }]
+        }));
+
+        const { result } = renderHook(() => useGamification());
+        await waitFor(() => expect(result.current.loading).toBe(false));
+
+        // Trigger action that would unlock it again
+        await act(async () => {
+             result.current.checkWorldAchievements('world1', 10, 10, 5);
+        });
+
+        // Should not crash and state should remain consistent
+        expect(result.current.unlockedAchievements.filter(a => a.id === 'first_world').length).toBe(1);
+    });
+});