Fix comparison badge to update in real-time across components

- Move comparison state from hook to shared context provider
- All components now share the same state instance
- Badge count updates immediately when schools are added/removed
- Add key prop to badge to re-trigger animation on count change
- Add storage event listener for cross-tab synchronization

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

nextjs-app/hooks/useComparison.ts

@@ -1,35 +1,25 @@
 /**
  * Custom hook for managing school comparison state
+ * Uses shared context for real-time updates across components
  */
 
 'use client';
 
-import { useState, useEffect, useCallback } from 'react';
 import useSWR from 'swr';
 import { fetcher } from '@/lib/api';
-import { getFromLocalStorage, setToLocalStorage } from '@/lib/utils';
-import type { School, ComparisonResponse } from '@/lib/types';
-
-const STORAGE_KEY = 'selectedSchools';
-const MAX_SCHOOLS = 5;
+import { useComparisonContext } from '@/context/ComparisonContext';
+import type { ComparisonResponse } from '@/lib/types';
 
 export function useComparison() {
-  const [selectedSchools, setSelectedSchools] = useState<School[]>([]);
-  const [isInitialized, setIsInitialized] = useState(false);
-
-  // Load from localStorage on mount
-  useEffect(() => {
-    const stored = getFromLocalStorage<School[]>(STORAGE_KEY, []);
-    setSelectedSchools(stored);
-    setIsInitialized(true);
-  }, []);
-
-  // Save to localStorage when schools change
-  useEffect(() => {
-    if (isInitialized) {
-      setToLocalStorage(STORAGE_KEY, selectedSchools);
-    }
-  }, [selectedSchools, isInitialized]);
+  const {
+    selectedSchools,
+    addSchool,
+    removeSchool,
+    clearAll,
+    isSelected,
+    canAddMore,
+    isInitialized,
+  } = useComparisonContext();
 
   // Fetch comparison data for selected schools
   const urns = selectedSchools.map((s) => s.urn).join(',');
@@ -38,40 +28,10 @@ export function useComparison() {
     fetcher,
     {
       revalidateOnFocus: false,
-      dedupingInterval: 10000, // 10 seconds
+      dedupingInterval: 10000,
     }
   );
 
-  const addSchool = useCallback((school: School) => {
-    setSelectedSchools((prev) => {
-      // Check if already selected
-      if (prev.some((s) => s.urn === school.urn)) {
-        return prev;
-      }
-
-      // Check max limit
-      if (prev.length >= MAX_SCHOOLS) {
-        alert(`Maximum ${MAX_SCHOOLS} schools can be compared`);
-        return prev;
-      }
-
-      return [...prev, school];
-    });
-  }, []);
-
-  const removeSchool = useCallback((urn: number) => {
-    setSelectedSchools((prev) => prev.filter((s) => s.urn !== urn));
-  }, []);
-
-  const clearAll = useCallback(() => {
-    setSelectedSchools([]);
-  }, []);
-
-  const isSelected = useCallback(
-    (urn: number) => selectedSchools.some((s) => s.urn === urn),
-    [selectedSchools]
-  );
-
   return {
     selectedSchools,
     comparisonData: data?.comparison,
@@ -81,7 +41,8 @@ export function useComparison() {
     removeSchool,
     clearAll,
     isSelected,
-    canAddMore: selectedSchools.length < MAX_SCHOOLS,
+    canAddMore,
+    isInitialized,
     mutate,
   };
 }