diff --git a/backend/src/routes/schedules/suggestions.js b/backend/src/routes/schedules/suggestions.js
index 1c9f00d..0a4f2a0 100644
--- a/backend/src/routes/schedules/suggestions.js
+++ b/backend/src/routes/schedules/suggestions.js
@@ -1,7 +1,7 @@
 /**
  * 추천 검색어 API 라우트
  */
-import { readFileSync, writeFileSync } from 'fs';
+import { readFile, writeFile } from 'fs/promises';
 import { SuggestionService } from '../../services/suggestions/index.js';
 import { reloadMorpheme, getUserDictPath } from '../../services/suggestions/morpheme.js';
 import { badRequest, serverError } from '../../utils/error.js';
@@ -139,7 +139,7 @@ export default async function suggestionsRoutes(fastify) {
   }, async (request, reply) => {
     try {
       const dictPath = getUserDictPath();
-      const content = readFileSync(dictPath, 'utf-8');
+      const content = await readFile(dictPath, 'utf-8');
       return { content };
     } catch (error) {
       if (error.code === 'ENOENT') {
@@ -180,7 +180,7 @@ export default async function suggestionsRoutes(fastify) {
 
     try {
       const dictPath = getUserDictPath();
-      writeFileSync(dictPath, content, 'utf-8');
+      await writeFile(dictPath, content, 'utf-8');
 
       // 형태소 분석기 리로드
       await reloadMorpheme();
diff --git a/backend/src/utils/cache.js b/backend/src/utils/cache.js
index db30612..185c0d4 100644
--- a/backend/src/utils/cache.js
+++ b/backend/src/utils/cache.js
@@ -41,15 +41,19 @@ export async function invalidate(redis, keys) {
 }
 
 /**
- * 패턴으로 캐시 무효화
+ * 패턴으로 캐시 무효화 (SCAN 사용으로 블로킹 방지)
  * @param {object} redis - Redis 클라이언트
  * @param {string} pattern - 키 패턴 (예: 'schedule:*')
  */
 export async function invalidatePattern(redis, pattern) {
-  const keys = await redis.keys(pattern);
-  if (keys.length > 0) {
-    await redis.del(...keys);
-  }
+  let cursor = '0';
+  do {
+    const [nextCursor, keys] = await redis.scan(cursor, 'MATCH', pattern, 'COUNT', 100);
+    cursor = nextCursor;
+    if (keys.length > 0) {
+      await redis.del(...keys);
+    }
+  } while (cursor !== '0');
 }
 
 // 캐시 키 생성 헬퍼
diff --git a/docs/improvements.md b/docs/improvements.md
index 1c971c3..faba54a 100644
--- a/docs/improvements.md
+++ b/docs/improvements.md
@@ -546,8 +546,8 @@ await writeFile(dictPath, content, 'utf-8');
 
 | 이슈 | 우선순위 | 상태 |
 |------|---------|------|
-| Redis KEYS → SCAN | Low | ⬜ 미해결 |
-| 동기식 파일 I/O | Low | ⬜ 미해결 |
+| Redis KEYS → SCAN | Low | ✅ 해결됨 |
+| 동기식 파일 I/O | Low | ✅ 해결됨 |
 
 ---
 
@@ -560,4 +560,4 @@ await writeFile(dictPath, content, 'utf-8');
 
 ---
 
-*마지막 업데이트: 2025-01*
+*마지막 업데이트: 2026-01-23*