diff --git a/src/main/repository/NoteRepository.ts b/src/main/repository/NoteRepository.ts
index 9492c68..8a3a996 100644
--- a/src/main/repository/NoteRepository.ts
+++ b/src/main/repository/NoteRepository.ts
@@ -40,6 +40,8 @@ export interface ImportNoteResult {
   status: ImportNoteStatus;
 }
 
+const KEBAB_CASE_RE = /^[a-z0-9-]+$/;
+
 export class NoteRepository {
   constructor(private db: Database.Database) {}
 
@@ -219,11 +221,15 @@ export class NoteRepository {
    * v0.2.3 #3 — AI prompt 의 vocabulary 후보. 사용 빈도 높은 태그 top-N.
    * source 무시 (AI+user 통합), kebab-case 통과한 것만 (한글/공백/대문자 제외).
    * deleted_at IS NULL 만 (휴지통 노트 태그 제외).
+   *
+   * Note: LIMIT 가 SQL 단계에서 먼저 적용된 후 regex 필터링이 후처리 됨.
+   * 따라서 반환 배열 length 가 limit 보다 작을 수 있음 (top-N 안에 비-kebab-case
+   * 태그가 섞여 있을 때). v0.2.3 dogfood 규모에서는 실용적 영향 없음.
    */
   getTopUsedTags(limit = 20): string[] {
     const rows = this.db
       .prepare(
-        `SELECT t.name, COUNT(*) c
+        `SELECT t.name, COUNT(*) AS c
            FROM tags t
            JOIN note_tags nt ON nt.tag_id = t.id
            JOIN notes n ON n.id = nt.note_id
@@ -235,7 +241,7 @@ export class NoteRepository {
       .all(limit) as Array<{ name: string; c: number }>;
     return rows
       .map((r) => r.name)
-      .filter((n) => /^[a-z0-9-]+$/.test(n));
+      .filter((n) => KEBAB_CASE_RE.test(n));
   }
 
   /**
diff --git a/tests/unit/NoteRepository.test.ts b/tests/unit/NoteRepository.test.ts
index c875f8a..8097b9b 100644
--- a/tests/unit/NoteRepository.test.ts
+++ b/tests/unit/NoteRepository.test.ts
@@ -681,11 +681,17 @@ describe('NoteRepository — failed retry helpers', () => {
   it('getTopUsedTags counts AI + user sources together', () => {
     const a = repo.create({ rawText: 'a' }).id;
     const b = repo.create({ rawText: 'b' }).id;
+    const c = repo.create({ rawText: 'c' }).id;
+    // design: 1 AI (a) + 1 user (b) = 2 total; meeting: 1 AI (c) = 1 total
+    // → design must rank first (proves source merging, not AI-only count)
+    // Note: updateUserAiFields REPLACES tags (DELETE+reinsert), so each note
+    // gets exactly the tags passed in the call.
     repo.updateAiResult(a, { title: 't', summary: 'x\ny\nz', tags: ['design'], provider: 'p' });
     repo.updateUserAiFields(b, { tags: ['design'] });
-    // design count 는 AI 1 + user 1 = 2
+    repo.updateAiResult(c, { title: 't', summary: 'x\ny\nz', tags: ['meeting'], provider: 'p' });
     const top = repo.getTopUsedTags();
-    expect(top).toContain('design');
+    expect(top[0]).toBe('design');  // 2 (AI+user) > 1 (AI only)
+    expect(top.indexOf('meeting')).toBeGreaterThan(0);
   });
 
   it('getTopUsedTags excludes tags from deleted notes', () => {