feat: add centralised store selectors

src/store/selectors.ts

@@ -0,0 +1,42 @@
+/**
+ * Centralised store selectors.
+ * Import from here instead of accessing store state inline to keep
+ * components decoupled from store internals.
+ */
+
+import { useSearchStore } from '@/app/store/searchStore';
+import { useNotificationStore } from '@/app/store/notificationStore';
+import { useQuizStore } from '@/app/store/quizStore';
+
+// ── Search selectors ──────────────────────────────────────────────────────────
+export const useSearchFilters = () =>
+  useSearchStore((s) => ({
+    difficulty: s.difficulty,
+    duration: s.duration,
+    topics: s.topics,
+    instructors: s.instructors,
+    sortBy: s.sortBy,
+    price: s.price,
+  }));
+
+export const useSearchHistory = () => useSearchStore((s) => s.searchHistory);
+
+// ── Notification selectors ────────────────────────────────────────────────────
+export const useUnreadNotifications = () =>
+  useNotificationStore((s) => s.notifications.filter((n) => !n.read));
+
+export const useUnreadCount = () =>
+  useNotificationStore((s) => s.notifications.filter((n) => !n.read).length);
+
+// ── Quiz selectors ────────────────────────────────────────────────────────────
+export const useCurrentQuestion = () =>
+  useQuizStore((s) =>
+    s.currentQuiz ? s.currentQuiz.questions[s.currentQuestionIndex] ?? null : null,
+  );
+
+export const useQuizProgress = () =>
+  useQuizStore((s) => ({
+    current: s.currentQuestionIndex + 1,
+    total: s.currentQuiz?.questions.length ?? 0,
+    isReviewMode: s.isReviewMode,
+  }));