fix: support diacritic-insensitive search indexing closes (#629)

src/services/searchIndex.ts

@@ -4,6 +4,7 @@ import { FilterValues } from '../components/mobile/FilterSheet';
 import { SearchResultItem } from '../components/mobile/SearchResultCard';
 import { Course } from '../types/course';
 import { appLogger } from '../utils/logger';
+import { normalizeText } from '../utils/stringUtils';
 import { buildTrie, Trie } from '../utils/trie';
 
 const INDEX_STORAGE_KEY = '@teachlink_search_index';
@@ -168,24 +169,24 @@ export function buildSearchIndex(courses: Course[]): PersistedSearchIndex {
     // Suggestions: full title and category phrases as well as individual words.
     suggestionSet.add(course.title);
     suggestionSet.add(course.category);
-    for (const t of tokenize(course.title)) suggestionSet.add(t);
+    for (const t of tokenize(normalizeText(course.title))) suggestionSet.add(t);
 
     // Title
-    const titleTokens = tokenize(course.title);
+    const titleTokens = tokenize(normalizeText(course.title));
     addWeightedTokens(entries, titleTokens, course.id, FIELD_WEIGHTS.title);
 
     // Category
-    for (const token of tokenize(course.category)) {
+    for (const token of tokenize(normalizeText(course.category))) {
       addEntry(entries, token, course.id, FIELD_WEIGHTS.category);
     }
 
     // Instructor name
-    for (const token of tokenize(course.instructor.name)) {
+    for (const token of tokenize(normalizeText(course.instructor.name))) {
       addEntry(entries, token, course.id, FIELD_WEIGHTS.instructor);
     }
 
     // Description (length-capped)
-    const descTokens = tokenize(course.description, MAX_DESC_TOKENS);
+    const descTokens = tokenize(normalizeText(course.description), MAX_DESC_TOKENS);
     addWeightedTokens(entries, descTokens, course.id, FIELD_WEIGHTS.description);
   }
 
@@ -274,7 +275,7 @@ export class SearchIndexService {
   search(query: string, filters: FilterValues = {}, maxResults = 50): SearchResultItem[] {
     if (!this.index || !this.tokenTrie) return [];
 
-    const tokens = tokenize(query);
+    const tokens = tokenize(normalizeText(query));
     if (tokens.length === 0) return [];
 
     const scoreMap = new Map<string, number>();

src/utils/stringUtils.ts

@@ -0,0 +1,8 @@
+/**
+ * Normalizes text by converting it to Unicode NFD form and removing diacritic marks.
+ * E.g., 'Café' -> 'Cafe', 'Résumé' -> 'Resume', 'München' -> 'Munchen', 'Ñoño' -> 'Nono'
+ */
+export function normalizeText(text: string): string {
+  if (!text) return '';
+  return text.normalize('NFD').replace(/[\u0300-\u036f]/g, '');
+}

tests/services/searchIndex.test.ts

@@ -0,0 +1,107 @@
+import { SearchIndexService } from '../../src/services/searchIndex';
+import { Course } from '../../src/types/course';
+
+describe('SearchIndexService diacritics normalization', () => {
+  let service: SearchIndexService;
+
+  beforeEach(() => {
+    service = new SearchIndexService();
+  });
+
+  it('finds course titled "Café" when searching "cafe"', async () => {
+    const courses: Course[] = [
+      {
+        id: 'course-1',
+        title: 'Café Communication',
+        description: 'Learn communication skills.',
+        instructor: { id: 'inst-1', name: 'John Doe' },
+        sections: [],
+        totalLessons: 5,
+        totalDuration: 60,
+        level: 'beginner',
+        category: 'Language',
+      },
+    ];
+
+    await service.buildFromCourses(courses);
+
+    // Test 'Cafe' / 'cafe' search finding 'Café'
+    const results = service.search('Cafe');
+    expect(results).toHaveLength(1);
+    expect(results[0].id).toBe('course-1');
+    expect(results[0].title).toBe('Café Communication'); // Original display text preserved
+  });
+
+  it('finds course titled "Résumé" when searching "Resume"', async () => {
+    const courses: Course[] = [
+      {
+        id: 'course-2',
+        title: 'Résumé Writing',
+        description: 'Professional CV preparation.',
+        instructor: { id: 'inst-2', name: 'Jane Doe' },
+        sections: [],
+        totalLessons: 5,
+        totalDuration: 60,
+        level: 'beginner',
+        category: 'Careers',
+      },
+    ];
+
+    await service.buildFromCourses(courses);
+
+    const results = service.search('Resume');
+    expect(results).toHaveLength(1);
+    expect(results[0].id).toBe('course-2');
+    expect(results[0].title).toBe('Résumé Writing'); // Original display text preserved
+  });
+
+  it('finds course titled "München" when searching "munchen"', async () => {
+    const courses: Course[] = [
+      {
+        id: 'course-3',
+        title: 'München History',
+        description: 'History of Munich (München).',
+        instructor: { id: 'inst-3', name: 'Karl' },
+        sections: [],
+        totalLessons: 5,
+        totalDuration: 60,
+        level: 'beginner',
+        category: 'History',
+      },
+    ];
+
+    await service.buildFromCourses(courses);
+
+    // Test 'munchen' finding 'München' (diacritics normalization)
+    const resultsMunchen = service.search('munchen');
+    expect(resultsMunchen).toHaveLength(1);
+    expect(resultsMunchen[0].id).toBe('course-3');
+
+    // Test 'Munich' finding 'München' (since 'Munich' is in description/indexed fields)
+    const resultsMunich = service.search('Munich');
+    expect(resultsMunich).toHaveLength(1);
+    expect(resultsMunich[0].id).toBe('course-3');
+  });
+
+  it('finds course titled "Ñoño" when searching "nono"', async () => {
+    const courses: Course[] = [
+      {
+        id: 'course-4',
+        title: 'El curso de Ñoño',
+        description: 'Un curso divertido.',
+        instructor: { id: 'inst-4', name: 'Nico' },
+        sections: [],
+        totalLessons: 5,
+        totalDuration: 60,
+        level: 'beginner',
+        category: 'Culture',
+      },
+    ];
+
+    await service.buildFromCourses(courses);
+
+    const results = service.search('nono');
+    expect(results).toHaveLength(1);
+    expect(results[0].id).toBe('course-4');
+  });
+});

tsconfig.json

@@ -6,14 +6,12 @@
     "jsx": "react-native",
     "esModuleInterop": true,
     "allowSyntheticDefaultImports": true,
-    "baseUrl": ".",
-    "ignoreDeprecations": "6.0",
     "paths": {
-      "@components/*": ["src/components/*"],
-      "@hooks/*": ["src/hooks/*"],
-      "@services/*": ["src/services/*"],
-      "@store/*": ["src/store/*"],
-      "@utils/*": ["src/utils/*"],
+      "@components/*": ["./src/components/*"],
+      "@hooks/*": ["./src/hooks/*"],
+      "@services/*": ["./src/services/*"],
+      "@store/*": ["./src/store/*"],
+      "@utils/*": ["./src/utils/*"],
       "@/components/*": ["./src/components/*", "./components/*"],
       "@/hooks/*": ["./src/hooks/*", "./hooks/*"],
       "@/constants/*": ["./constants/*"],