refactor: complete P0-P1 improvements

Constants migration:
- server-agent.ts: SERVER_CONSULTATION_STATUS, LANGUAGE_CODE
- troubleshoot-agent.ts: TROUBLESHOOT_STATUS
- notification.ts: NOTIFICATION_TYPE

API improvements:
- search-tool.ts: Zod schema validation for Brave/Context7 APIs
- api-helper.ts: Centralized API call utility with retry/timeout

Testing:
- kv-cache.test.ts: 38 test cases for cache abstraction

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

src/constants/index.ts

@@ -139,6 +139,44 @@ export const DEPOSIT_ACTION = {
   REJECT: 'reject',
 } as const;
 
+/**
+ * Notification types for admin alerts
+ */
+export const NOTIFICATION_TYPE = {
+  CIRCUIT_BREAKER: 'circuit_breaker',
+  RETRY_EXHAUSTED: 'retry_exhausted',
+  API_ERROR: 'api_error',
+} as const;
+
+/**
+ * Troubleshoot session statuses
+ */
+export const TROUBLESHOOT_STATUS = {
+  GATHERING: 'gathering',
+  DIAGNOSING: 'diagnosing',
+  SOLVING: 'solving',
+} as const;
+
+/**
+ * Server consultation session statuses
+ */
+export const SERVER_CONSULTATION_STATUS = {
+  GATHERING: 'gathering',
+  RECOMMENDING: 'recommending',
+  SELECTING: 'selecting',
+  COMPLETED: 'completed',
+} as const;
+
+/**
+ * Language codes for multi-language support
+ */
+export const LANGUAGE_CODE = {
+  KOREAN: 'ko',
+  JAPANESE: 'ja',
+  CHINESE: 'zh',
+  ENGLISH: 'en',
+} as const;
+
 /**
  * Helper to create session key with user ID
  *
@@ -183,3 +221,7 @@ export type ServerOrderStatus = typeof SERVER_ORDER_STATUS[keyof typeof SERVER_O
 export type ServerAction = typeof SERVER_ACTION[keyof typeof SERVER_ACTION];
 export type DomainAction = typeof DOMAIN_ACTION[keyof typeof DOMAIN_ACTION];
 export type DepositAction = typeof DEPOSIT_ACTION[keyof typeof DEPOSIT_ACTION];
+export type NotificationType = typeof NOTIFICATION_TYPE[keyof typeof NOTIFICATION_TYPE];
+export type TroubleshootStatus = typeof TROUBLESHOOT_STATUS[keyof typeof TROUBLESHOOT_STATUS];
+export type ServerConsultationStatus = typeof SERVER_CONSULTATION_STATUS[keyof typeof SERVER_CONSULTATION_STATUS];
+export type LanguageCode = typeof LANGUAGE_CODE[keyof typeof LANGUAGE_CODE];

src/server-agent.ts

@@ -13,6 +13,7 @@ import type { Env, ServerSession, BandwidthInfo, RecommendResponse } from './typ
 import { createLogger } from './utils/logger';
 import { executeSearchWeb, executeLookupDocs } from './tools/search-tool';
 import { formatTrafficInfo } from './utils/formatters';
+import { SERVER_CONSULTATION_STATUS, LANGUAGE_CODE } from './constants';
 
 const logger = createLogger('server-agent');
 
@@ -683,7 +684,7 @@ export async function processServerConsultation(
       // 새 세션 생성하고 시작 메시지 반환
       const newSession: ServerSession = {
         telegramUserId: session.telegramUserId,
-        status: 'gathering',
+        status: SERVER_CONSULTATION_STATUS.GATHERING,
         collectedInfo: {},
         messages: [],
         createdAt: Date.now(),
@@ -699,10 +700,10 @@ export async function processServerConsultation(
       status: session.status,
       hasLastRecommendation: !!session.lastRecommendation,
       recommendationCount: session.lastRecommendation?.recommendations?.length || 0,
-      willProcessSelection: session.status === 'selecting' && !!session.lastRecommendation
+      willProcessSelection: session.status === SERVER_CONSULTATION_STATUS.SELECTING && !!session.lastRecommendation
     });
 
-    if (session.status === 'selecting' && session.lastRecommendation) {
+    if (session.status === SERVER_CONSULTATION_STATUS.SELECTING && session.lastRecommendation) {
       // 상담과 무관한 키워드 감지 (selecting 상태에서만)
       // 명확히 다른 기능 요청인 경우 세션 종료하고 일반 처리로 전환
       const unrelatedPatterns = /기억|날씨|계산|검색|도메인|입금|충전|잔액|시간|문서/;
@@ -812,7 +813,7 @@ export async function processServerConsultation(
       }
 
       // Mark session as recommending
-      session.status = 'recommending';
+      session.status = SERVER_CONSULTATION_STATUS.RECOMMENDING;
       await saveServerSession(env.DB, session.telegramUserId, session);
 
       // 1. Call recommendation API (추천 먼저 받기)
@@ -877,7 +878,7 @@ export async function processServerConsultation(
           use_case: session.collectedInfo.useCase || '웹 서비스',
           region_preference: finalRegionPreference,
           budget_limit: session.collectedInfo.budgetLimit,
-          lang: 'ko',
+          lang: LANGUAGE_CODE.KOREAN,
         },
         env
       );
@@ -927,14 +928,14 @@ export async function processServerConsultation(
             use_case: session.collectedInfo.useCase || '웹 서비스',
             region_preference: session.collectedInfo.regionPreference,
             budget_limit: session.collectedInfo.budgetLimit,
-            lang: 'ko',
+            lang: LANGUAGE_CODE.KOREAN,
           },
           env,
           session.telegramUserId
         );
 
         // Mark session as selecting (사용자 선택 대기)
-        session.status = 'selecting';
+        session.status = SERVER_CONSULTATION_STATUS.SELECTING;
         await saveServerSession(env.DB, session.telegramUserId, session);
 
         // 4. 추천 결과 + AI 검토 코멘트 (검토 코멘트는 마지막에)
@@ -942,14 +943,14 @@ export async function processServerConsultation(
         return `${formattedRecommendation}\n\n💬 ${reviewResult.message}\n\n💡 원하는 서버 번호를 선택해주세요 (예: 1번)`;
       } else {
         // 추천 결과 없음 - 세션 삭제
-        session.status = 'completed';
+        session.status = SERVER_CONSULTATION_STATUS.COMPLETED;
         await deleteServerSession(env.DB, session.telegramUserId);
 
         return `${aiResult.message}\n\n조건에 맞는 서버를 찾지 못했습니다.`;
       }
     } else {
       // Continue gathering information
-      session.status = 'gathering';
+      session.status = SERVER_CONSULTATION_STATUS.GATHERING;
       await saveServerSession(env.DB, session.telegramUserId, session);
 
       return aiResult.message;

src/services/notification.ts

@@ -1,13 +1,15 @@
 import { Env } from '../types';
 import { createLogger } from '../utils/logger';
+import { NOTIFICATION_TYPE } from '../constants';
+import type { NotificationType } from '../constants';
 
 const logger = createLogger('notification');
 
 /**
  * 알림 유형별 메시지 템플릿
  */
-const NOTIFICATION_TEMPLATES = {
+const NOTIFICATION_TEMPLATES: Record<NotificationType, (details: NotificationDetails) => string> = {
-  circuit_breaker: (details: NotificationDetails) => `
+  [NOTIFICATION_TYPE.CIRCUIT_BREAKER]: (details: NotificationDetails) => `
 🚨 시스템 알림 (Circuit Breaker)
 
 서비스: ${details.service}
@@ -19,7 +21,7 @@ const NOTIFICATION_TEMPLATES = {
 ${details.context ? `\n추가 정보:\n${details.context}` : ''}
   `.trim(),
 
-  retry_exhausted: (details: NotificationDetails) => `
+  [NOTIFICATION_TYPE.RETRY_EXHAUSTED]: (details: NotificationDetails) => `
 ⚠️ 시스템 알림 (재시도 실패)
 
 서비스: ${details.service}
@@ -31,7 +33,7 @@ ${details.context ? `\n추가 정보:\n${details.context}` : ''}
 ${details.context ? `\n추가 정보:\n${details.context}` : ''}
   `.trim(),
 
-  api_error: (details: NotificationDetails) => `
+  [NOTIFICATION_TYPE.API_ERROR]: (details: NotificationDetails) => `
 🔴 시스템 알림 (API 에러)
 
 서비스: ${details.service}
@@ -42,12 +44,7 @@ ${details.context ? `\n추가 정보:\n${details.context}` : ''}
 즉시 확인이 필요합니다.
 ${details.context ? `\n추가 정보:\n${details.context}` : ''}
   `.trim(),
-} as const;
+};
-
-/**
- * 알림 유형
- */
-export type NotificationType = keyof typeof NOTIFICATION_TEMPLATES;
 
 /**
  * 알림 상세 정보

src/tools/search-tool.ts

@@ -1,11 +1,8 @@
 import type {
   Env,
-  OpenAIResponse,
+  OpenAIResponse
-  BraveSearchResponse,
-  BraveSearchResult,
-  Context7SearchResponse,
-  Context7DocsResponse
 } from '../types';
+import { z } from 'zod';
 import { retryWithBackoff, RetryError } from '../utils/retry';
 import { createLogger } from '../utils/logger';
 import { getOpenAIUrl } from '../utils/api-urls';
@@ -13,6 +10,39 @@ import { ERROR_MESSAGES } from '../constants/messages';
 
 const logger = createLogger('search-tool');
 
+// Zod schemas for API response validation
+const BraveSearchResultSchema = z.object({
+  title: z.string(),
+  url: z.string(),
+  description: z.string().optional(),
+});
+
+const BraveSearchResponseSchema = z.object({
+  web: z.object({
+    results: z.array(BraveSearchResultSchema),
+  }).optional(),
+  query: z.object({
+    original: z.string(),
+  }).optional(),
+});
+
+const Context7LibrarySchema = z.object({
+  id: z.string(),
+  name: z.string().optional(),
+});
+
+const Context7SearchResponseSchema = z.object({
+  libraries: z.array(Context7LibrarySchema).optional(),
+  results: z.array(Context7LibrarySchema).optional(),  // API가 results로 반환
+});
+
+const Context7DocsResponseSchema = z.object({
+  context: z.string().optional(),
+  content: z.string().optional(),
+  message: z.string().optional(),
+  error: z.string().optional(),
+});
+
 export const searchWebTool = {
   type: 'function',
   function: {
@@ -143,7 +173,20 @@ export async function executeSearchWeb(args: { query: string }, env?: Env): Prom
     if (!response.ok) {
       return `🔍 검색 오류: ${response.status}`;
     }
-    const data = await response.json() as BraveSearchResponse;
+
+    // Zod를 사용한 응답 검증
+    const json = await response.json();
+    const parsed = BraveSearchResponseSchema.safeParse(json);
+
+    if (!parsed.success) {
+      logger.warn('Brave API 응답 파싱 실패', {
+        error: parsed.error.issues,
+        receivedData: JSON.stringify(json).substring(0, 200)
+      });
+      return `🔍 검색 결과 처리 중 오류가 발생했습니다. 잠시 후 다시 시도해주세요.`;
+    }
+
+    const data = parsed.data;
 
     // Web 검색 결과 파싱
     const webResults = data.web?.results || [];
@@ -151,8 +194,8 @@ export async function executeSearchWeb(args: { query: string }, env?: Env): Prom
       return `🔍 "${query}"에 대한 검색 결과가 없습니다.`;
     }
 
-    const results = webResults.slice(0, 3).map((r: BraveSearchResult, i: number) =>
+    const results = webResults.slice(0, 3).map((r, i: number) =>
-      `${i + 1}. <b>${r.title}</b>\n   ${r.description}\n   ${r.url}`
+      `${i + 1}. <b>${r.title}</b>\n   ${r.description || '설명 없음'}\n   ${r.url}`
     ).join('\n\n');
 
     // 번역된 경우 원본 쿼리도 표시
@@ -192,13 +235,27 @@ export async function executeLookupDocs(args: { library: string; query: string }
       () => fetch(searchUrl),
       { maxRetries: 3 }
     );
-    const searchData = await searchResponse.json() as Context7SearchResponse;
 
-    if (!searchData.libraries?.length) {
+    // Zod를 사용한 검색 응답 검증
+    const searchJson = await searchResponse.json();
+    const searchParsed = Context7SearchResponseSchema.safeParse(searchJson);
+
+    if (!searchParsed.success) {
+      logger.warn('Context7 검색 API 응답 파싱 실패', {
+        error: searchParsed.error.issues,
+        receivedData: JSON.stringify(searchJson).substring(0, 200)
+      });
+      return `📚 라이브러리 검색 중 오류가 발생했습니다. 잠시 후 다시 시도해주세요.`;
+    }
+
+    const searchData = searchParsed.data;
+    const libraries = searchData.libraries || searchData.results || [];
+
+    if (libraries.length === 0) {
       return `📚 "${library}" 라이브러리를 찾을 수 없습니다.`;
     }
 
-    const libraryId = searchData.libraries[0].id;
+    const libraryId = libraries[0].id;
 
     // 3. 문서 조회
     const docsUrl = `${env?.CONTEXT7_API_BASE || 'https://context7.com/api/v2'}/context?libraryId=${encodeURIComponent(libraryId)}&query=${encodeURIComponent(query)}`;
@@ -206,7 +263,20 @@ export async function executeLookupDocs(args: { library: string; query: string }
       () => fetch(docsUrl),
       { maxRetries: 3 }
     );
-    const docsData = await docsResponse.json() as Context7DocsResponse;
+
+    // Zod를 사용한 문서 응답 검증
+    const docsJson = await docsResponse.json();
+    const docsParsed = Context7DocsResponseSchema.safeParse(docsJson);
+
+    if (!docsParsed.success) {
+      logger.warn('Context7 문서 API 응답 파싱 실패', {
+        error: docsParsed.error.issues,
+        receivedData: JSON.stringify(docsJson).substring(0, 200)
+      });
+      return `📚 문서 조회 중 오류가 발생했습니다. 잠시 후 다시 시도해주세요.`;
+    }
+
+    const docsData = docsParsed.data;
 
     if (docsData.error) {
       return `📚 문서 조회 실패: ${docsData.message || docsData.error}`;

src/troubleshoot-agent.ts

@@ -17,6 +17,7 @@
 import type { Env, TroubleshootSession } from './types';
 import { createLogger } from './utils/logger';
 import { executeSearchWeb, executeLookupDocs } from './tools/search-tool';
+import { TROUBLESHOOT_STATUS } from './constants';
 
 const logger = createLogger('troubleshoot-agent');
 
@@ -435,11 +436,11 @@ export async function processTroubleshoot(
 
     // Update session status based on action
     if (aiResult.action === 'diagnose') {
-      session.status = 'diagnosing';
+      session.status = TROUBLESHOOT_STATUS.DIAGNOSING;
     } else if (aiResult.action === 'solve') {
-      session.status = 'solving';
+      session.status = TROUBLESHOOT_STATUS.SOLVING;
     } else {
-      session.status = 'gathering';
+      session.status = TROUBLESHOOT_STATUS.GATHERING;
     }
 
     await saveTroubleshootSession(env.SESSION_KV, session.telegramUserId, session);

src/utils/api-helper.ts

@@ -0,0 +1,157 @@
+/**
+ * API 호출 추상화 유틸리티
+ *
+ * Cloudflare Workers 환경에서 외부 API 호출을 위한 추상화 레이어입니다.
+ * 재시도 로직, 타임아웃, 응답 검증을 자동으로 처리합니다.
+ *
+ * @module api-helper
+ * @example
+ * ```typescript
+ * import { callApi } from './utils/api-helper';
+ * import { z } from 'zod';
+ *
+ * // 스키마 정의
+ * const UserSchema = z.object({
+ *   id: z.number(),
+ *   name: z.string(),
+ * });
+ *
+ * // API 호출 (자동 검증)
+ * const user = await callApi('https://api.example.com/user', {
+ *   schema: UserSchema,
+ * });
+ * ```
+ */
+
+import { z } from 'zod';
+import { createLogger } from './logger';
+import { retryWithBackoff } from './retry';
+
+const logger = createLogger('api-helper');
+
+/**
+ * API 호출 옵션 인터페이스
+ *
+ * @template T - 응답 타입
+ */
+export interface ApiOptions<T> {
+  /** HTTP 메서드 (기본값: 'GET') */
+  method?: 'GET' | 'POST' | 'PUT' | 'DELETE';
+  /** HTTP 헤더 (기본 헤더와 병합됨) */
+  headers?: Record<string, string>;
+  /** 요청 본문 (JSON으로 자동 직렬화) */
+  body?: Record<string, unknown>;
+  /** 타임아웃 (밀리초, 기본값: 30000) */
+  timeout?: number;
+  /** 재시도 횟수 (기본값: 3) */
+  retries?: number;
+  /** 응답 검증 스키마 (Zod) */
+  schema?: z.ZodType<T>;
+}
+
+/**
+ * 외부 API 호출 추상화 함수
+ *
+ * 다음 기능을 자동으로 처리합니다:
+ * - 재시도 로직 (지수 백오프 + 지터)
+ * - 타임아웃 제어
+ * - JSON 응답 파싱
+ * - 응답 검증 (Zod 스키마)
+ * - 구조화된 로깅
+ *
+ * @template T - 응답 타입
+ * @param url - 호출할 API URL
+ * @param options - API 호출 옵션
+ * @returns 파싱 및 검증된 응답 데이터
+ * @throws Error if API call fails after retries
+ *
+ * @example
+ * ```typescript
+ * // 기본 GET 요청
+ * const data = await callApi<{ status: string }>('https://api.example.com/health');
+ *
+ * // POST 요청 with body
+ * const result = await callApi('https://api.example.com/data', {
+ *   method: 'POST',
+ *   body: { name: 'test' },
+ * });
+ *
+ * // 스키마 검증
+ * const ResponseSchema = z.object({
+ *   success: z.boolean(),
+ *   data: z.array(z.string()),
+ * });
+ *
+ * const validated = await callApi('https://api.example.com/list', {
+ *   schema: ResponseSchema,
+ * });
+ *
+ * // 커스텀 타임아웃 및 재시도
+ * const important = await callApi('https://api.example.com/critical', {
+ *   timeout: 60000,  // 60초
+ *   retries: 5,      // 5회 재시도
+ * });
+ * ```
+ */
+export async function callApi<T>(
+  url: string,
+  options?: ApiOptions<T>
+): Promise<T> {
+  return retryWithBackoff(async () => {
+    const controller = new AbortController();
+    const timeoutId = setTimeout(() => controller.abort(), options?.timeout || 30000);
+
+    try {
+      logger.debug('API 호출 시작', {
+        url,
+        method: options?.method || 'GET',
+        timeout: options?.timeout || 30000,
+      });
+
+      const response = await fetch(url, {
+        method: options?.method || 'GET',
+        headers: {
+          'Accept': 'application/json',
+          'Content-Type': 'application/json',
+          ...options?.headers,
+        },
+        body: options?.body ? JSON.stringify(options.body) : undefined,
+        signal: controller.signal,
+      });
+
+      if (!response.ok) {
+        logger.error('API 호출 실패', undefined, {
+          url,
+          status: response.status,
+          statusText: response.statusText,
+        });
+        throw new Error(`API error: ${response.status} ${response.statusText}`);
+      }
+
+      const json = await response.json();
+      
+      if (options?.schema) {
+        try {
+          const validated = options.schema.parse(json);
+          logger.debug('API 응답 검증 성공', { url });
+          return validated;
+        } catch (error) {
+          logger.error('API 응답 검증 실패', error as Error, {
+            url,
+            response: json,
+          });
+          throw error;
+        }
+      }
+      
+      logger.debug('API 호출 성공', { url });
+      return json as T;
+    } finally {
+      clearTimeout(timeoutId);
+    }
+  }, { 
+    maxRetries: options?.retries || 3,
+    initialDelayMs: 1000,
+    maxDelayMs: 10000,
+  });
+}

tests/kv-cache.test.ts

@@ -0,0 +1,498 @@
+/**
+ * Comprehensive Unit Tests for kv-cache.ts
+ *
+ * 테스트 범위:
+ * 1. KVCache 기본 CRUD 작업 (get, set, delete)
+ * 2. TTL 기능 (expirationTtl)
+ * 3. getOrSet 패턴 (cache-aside pattern)
+ * 4. exists 체크
+ * 5. Rate limiting 로직
+ * 6. 에러 핸들링
+ * 7. Prefix 분리 (rate vs session)
+ *
+ * NOTE: 이 테스트는 DB가 필요 없으므로 setup.ts를 import하지 않습니다.
+ */
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import {
+  KVCache,
+  createRateLimitCache,
+  createSessionCache,
+  checkRateLimitWithCache,
+} from '../src/services/kv-cache';
+
+/**
+ * Mock KVNamespace implementation
+ * - In-memory Map으로 실제 KV 동작 시뮬레이션
+ * - TTL 자동 만료 로직 포함
+ */
+const createMockKV = () => {
+  const store = new Map<string, { value: string; expiration?: number }>();
+
+  return {
+    get: vi.fn(async (key: string, type?: string) => {
+      const entry = store.get(key);
+      if (!entry) return null;
+
+      // TTL 만료 확인
+      if (entry.expiration && entry.expiration < Date.now() / 1000) {
+        store.delete(key);
+        return null;
+      }
+
+      // type이 'json'이면 파싱해서 반환
+      if (type === 'json') {
+        try {
+          return JSON.parse(entry.value);
+        } catch {
+          return null;
+        }
+      }
+
+      return entry.value;
+    }),
+    put: vi.fn(async (key: string, value: string, options?: { expirationTtl?: number }) => {
+      const expiration = options?.expirationTtl
+        ? Math.floor(Date.now() / 1000) + options.expirationTtl
+        : undefined;
+      store.set(key, { value, expiration });
+    }),
+    delete: vi.fn(async (key: string) => {
+      store.delete(key);
+    }),
+    _store: store, // 테스트용 직접 접근
+  };
+};
+
+describe('KVCache - Basic Operations', () => {
+  let mockKV: ReturnType<typeof createMockKV>;
+  let cache: KVCache;
+
+  beforeEach(() => {
+    mockKV = createMockKV();
+    cache = new KVCache(mockKV as unknown as KVNamespace, 'test');
+  });
+
+  describe('get/set', () => {
+    it('should store and retrieve simple string values', async () => {
+      await cache.set('key1', 'value1');
+      const result = await cache.get<string>('key1');
+      expect(result).toBe('value1');
+    });
+
+    it('should store and retrieve object values', async () => {
+      const data = { name: 'John', age: 30 };
+      await cache.set('user', data);
+      const result = await cache.get<typeof data>('user');
+      expect(result).toEqual(data);
+    });
+
+    it('should return null for missing keys', async () => {
+      const result = await cache.get('nonexistent');
+      expect(result).toBeNull();
+    });
+
+    it('should use prefix in key names', async () => {
+      await cache.set('key1', 'value1');
+      expect(mockKV.put).toHaveBeenCalledWith(
+        'test:key1',
+        JSON.stringify('value1'),
+        undefined
+      );
+    });
+
+    it('should handle empty prefix', async () => {
+      const noPrefixCache = new KVCache(mockKV as unknown as KVNamespace, '');
+      await noPrefixCache.set('key1', 'value1');
+      expect(mockKV.put).toHaveBeenCalledWith('key1', JSON.stringify('value1'), undefined);
+    });
+  });
+
+  describe('TTL expiration', () => {
+    it('should store value with TTL', async () => {
+      await cache.set('key1', 'value1', 60);
+      expect(mockKV.put).toHaveBeenCalledWith(
+        'test:key1',
+        JSON.stringify('value1'),
+        { expirationTtl: 60 }
+      );
+    });
+
+    it('should respect TTL and expire values', async () => {
+      // TTL 1초로 설정
+      await cache.set('key1', 'value1', 1);
+
+      // 1.1초 대기 (TTL 만료)
+      await new Promise(resolve => setTimeout(resolve, 1100));
+
+      const result = await cache.get('key1');
+      expect(result).toBeNull();
+    });
+
+    it('should not expire values without TTL', async () => {
+      await cache.set('key1', 'value1'); // TTL 없음
+      const result = await cache.get<string>('key1');
+      expect(result).toBe('value1');
+    });
+  });
+
+  describe('delete', () => {
+    it('should delete existing keys', async () => {
+      await cache.set('key1', 'value1');
+      const success = await cache.delete('key1');
+
+      expect(success).toBe(true);
+      expect(mockKV.delete).toHaveBeenCalledWith('test:key1');
+
+      const result = await cache.get('key1');
+      expect(result).toBeNull();
+    });
+
+    it('should return true even for non-existent keys', async () => {
+      const success = await cache.delete('nonexistent');
+      expect(success).toBe(true);
+    });
+  });
+
+  describe('exists', () => {
+    it('should return true for existing keys', async () => {
+      await cache.set('key1', 'value1');
+      const exists = await cache.exists('key1');
+      expect(exists).toBe(true);
+    });
+
+    it('should return false for missing keys', async () => {
+      const exists = await cache.exists('nonexistent');
+      expect(exists).toBe(false);
+    });
+
+    it('should return false for expired keys', async () => {
+      await cache.set('key1', 'value1', 1); // TTL 1초
+      await new Promise(resolve => setTimeout(resolve, 1100)); // 1.1초 대기
+
+      const exists = await cache.exists('key1');
+      expect(exists).toBe(false);
+    });
+  });
+});
+
+describe('KVCache - getOrSet Pattern', () => {
+  let mockKV: ReturnType<typeof createMockKV>;
+  let cache: KVCache;
+
+  beforeEach(() => {
+    mockKV = createMockKV();
+    cache = new KVCache(mockKV as unknown as KVNamespace, 'test');
+  });
+
+  it('should return cached value if exists', async () => {
+    const factory = vi.fn(async () => 'new-value');
+
+    // 먼저 캐시에 저장
+    await cache.set('key1', 'cached-value');
+
+    // getOrSet 호출
+    const result = await cache.getOrSet('key1', factory);
+
+    expect(result).toBe('cached-value');
+    expect(factory).not.toHaveBeenCalled(); // factory는 호출 안됨
+  });
+
+  it('should call factory and cache result if not exists', async () => {
+    const factory = vi.fn(async () => 'new-value');
+
+    const result = await cache.getOrSet('key1', factory);
+
+    expect(result).toBe('new-value');
+    expect(factory).toHaveBeenCalledTimes(1);
+
+    // 캐시에 저장되었는지 확인
+    const cached = await cache.get<string>('key1');
+    expect(cached).toBe('new-value');
+  });
+
+  it('should respect TTL in getOrSet', async () => {
+    const factory = vi.fn(async () => 'new-value');
+
+    await cache.getOrSet('key1', factory, 60);
+
+    expect(mockKV.put).toHaveBeenCalledWith(
+      'test:key1',
+      JSON.stringify('new-value'),
+      { expirationTtl: 60 }
+    );
+  });
+
+  it('should handle factory errors gracefully', async () => {
+    const factory = vi.fn(async () => {
+      throw new Error('Factory failed');
+    });
+
+    await expect(cache.getOrSet('key1', factory)).rejects.toThrow('Factory failed');
+
+    // 캐시에 저장되지 않았는지 확인
+    const cached = await cache.get('key1');
+    expect(cached).toBeNull();
+  });
+});
+
+describe('KVCache - Error Handling', () => {
+  let mockKV: ReturnType<typeof createMockKV>;
+  let cache: KVCache;
+
+  beforeEach(() => {
+    mockKV = createMockKV();
+    cache = new KVCache(mockKV as unknown as KVNamespace, 'test');
+  });
+
+  it('should return null on get() error', async () => {
+    mockKV.get.mockRejectedValueOnce(new Error('KV get failed'));
+
+    const result = await cache.get('key1');
+    expect(result).toBeNull();
+  });
+
+  it('should return false on set() error', async () => {
+    mockKV.put.mockRejectedValueOnce(new Error('KV put failed'));
+
+    const success = await cache.set('key1', 'value1');
+    expect(success).toBe(false);
+  });
+
+  it('should return false on delete() error', async () => {
+    mockKV.delete.mockRejectedValueOnce(new Error('KV delete failed'));
+
+    const success = await cache.delete('key1');
+    expect(success).toBe(false);
+  });
+
+  it('should handle JSON parse errors', async () => {
+    // 잘못된 JSON을 직접 저장
+    mockKV._store.set('test:key1', { value: 'invalid-json{', expiration: undefined });
+
+    const result = await cache.get('key1');
+    expect(result).toBeNull();
+  });
+});
+
+describe('Rate Limiting', () => {
+  let mockKV: ReturnType<typeof createMockKV>;
+  let cache: KVCache;
+
+  beforeEach(() => {
+    mockKV = createMockKV();
+    cache = createRateLimitCache(mockKV as unknown as KVNamespace);
+  });
+
+  it('should use "rate" prefix', async () => {
+    await cache.set('user1', 'test');
+    expect(mockKV.put).toHaveBeenCalledWith(
+      'rate:user1',
+      expect.any(String),
+      undefined
+    );
+  });
+
+  describe('checkRateLimitWithCache', () => {
+    it('should allow first request', async () => {
+      const allowed = await checkRateLimitWithCache(cache, 'user1', 30, 60);
+      expect(allowed).toBe(true);
+
+      // count=1로 저장되었는지 확인
+      const data = await cache.get<{ count: number; windowStart: number }>('user1');
+      expect(data?.count).toBe(1);
+    });
+
+    it('should allow requests within limit', async () => {
+      // 30번 요청 허용
+      for (let i = 0; i < 30; i++) {
+        const allowed = await checkRateLimitWithCache(cache, 'user1', 30, 60);
+        expect(allowed).toBe(true);
+      }
+
+      // count=30인지 확인
+      const data = await cache.get<{ count: number; windowStart: number }>('user1');
+      expect(data?.count).toBe(30);
+    });
+
+    it('should block requests over limit', async () => {
+      // 30번 요청
+      for (let i = 0; i < 30; i++) {
+        await checkRateLimitWithCache(cache, 'user1', 30, 60);
+      }
+
+      // 31번째 요청은 차단
+      const allowed = await checkRateLimitWithCache(cache, 'user1', 30, 60);
+      expect(allowed).toBe(false);
+    });
+
+    it('should reset window after expiration', async () => {
+      // windowSeconds=1로 설정 (1초 윈도우)
+      await checkRateLimitWithCache(cache, 'user1', 30, 1);
+
+      // 2초 대기 (윈도우 만료)
+      await new Promise(resolve => setTimeout(resolve, 2000));
+
+      // 새 윈도우 시작되어야 함
+      const allowed = await checkRateLimitWithCache(cache, 'user1', 30, 1);
+      expect(allowed).toBe(true);
+
+      // count=1로 리셋되었는지 확인
+      const data = await cache.get<{ count: number; windowStart: number }>('user1');
+      expect(data?.count).toBe(1);
+    });
+
+    it('should handle different users independently', async () => {
+      // user1: 30번 요청
+      for (let i = 0; i < 30; i++) {
+        await checkRateLimitWithCache(cache, 'user1', 30, 60);
+      }
+
+      // user2: 아직 요청 없음 (허용되어야 함)
+      const allowed = await checkRateLimitWithCache(cache, 'user2', 30, 60);
+      expect(allowed).toBe(true);
+    });
+
+    it('should track count correctly', async () => {
+      await checkRateLimitWithCache(cache, 'user1', 30, 60); // count=1
+      await checkRateLimitWithCache(cache, 'user1', 30, 60); // count=2
+      await checkRateLimitWithCache(cache, 'user1', 30, 60); // count=3
+
+      const data = await cache.get<{ count: number; windowStart: number }>('user1');
+      expect(data?.count).toBe(3);
+    });
+
+    it('should handle concurrent requests', async () => {
+      // 동시에 10개의 요청
+      const promises = Array(10).fill(null).map(() =>
+        checkRateLimitWithCache(cache, 'user1', 30, 60)
+      );
+
+      const results = await Promise.all(promises);
+
+      // 모두 허용되어야 함 (10 <= 30)
+      expect(results.every(r => r)).toBe(true);
+
+      // count=10인지 확인 (race condition 가능성 있으나 테스트 환경에서는 순차 실행)
+      const data = await cache.get<{ count: number; windowStart: number }>('user1');
+      expect(data?.count).toBeGreaterThan(0);
+      expect(data?.count).toBeLessThanOrEqual(10);
+    });
+  });
+});
+
+describe('Session Cache', () => {
+  let mockKV: ReturnType<typeof createMockKV>;
+  let cache: KVCache;
+
+  beforeEach(() => {
+    mockKV = createMockKV();
+    cache = createSessionCache(mockKV as unknown as KVNamespace);
+  });
+
+  it('should use "session" prefix', async () => {
+    await cache.set('user1', { state: 'active' });
+    expect(mockKV.put).toHaveBeenCalledWith(
+      'session:user1',
+      expect.any(String),
+      undefined
+    );
+  });
+
+  it('should store and retrieve session data', async () => {
+    const sessionData = {
+      state: 'gathering',
+      collectedInfo: { purpose: '블로그' },
+    };
+
+    await cache.set('server_session:123', sessionData, 3600);
+
+    const result = await cache.get<typeof sessionData>('server_session:123');
+    expect(result).toEqual(sessionData);
+  });
+});
+
+describe('Prefix Isolation', () => {
+  let mockKV: ReturnType<typeof createMockKV>;
+  let rateCache: KVCache;
+  let sessionCache: KVCache;
+
+  beforeEach(() => {
+    mockKV = createMockKV();
+    rateCache = createRateLimitCache(mockKV as unknown as KVNamespace);
+    sessionCache = createSessionCache(mockKV as unknown as KVNamespace);
+  });
+
+  it('should isolate keys between rate and session caches', async () => {
+    await rateCache.set('user1', 'rate-data');
+    await sessionCache.set('user1', 'session-data');
+
+    // rate:user1과 session:user1은 다른 키
+    const rateData = await rateCache.get<string>('user1');
+    const sessionData = await sessionCache.get<string>('user1');
+
+    expect(rateData).toBe('rate-data');
+    expect(sessionData).toBe('session-data');
+  });
+
+  it('should store keys with correct prefixes', async () => {
+    await rateCache.set('user1', 'test');
+    await sessionCache.set('user1', 'test');
+
+    expect(mockKV._store.has('rate:user1')).toBe(true);
+    expect(mockKV._store.has('session:user1')).toBe(true);
+    expect(mockKV._store.has('user1')).toBe(false); // prefix 없는 키는 없어야 함
+  });
+});
+
+describe('Complex Data Types', () => {
+  let mockKV: ReturnType<typeof createMockKV>;
+  let cache: KVCache;
+
+  beforeEach(() => {
+    mockKV = createMockKV();
+    cache = new KVCache(mockKV as unknown as KVNamespace, 'test');
+  });
+
+  it('should handle nested objects', async () => {
+    const data = {
+      user: {
+        id: 1,
+        profile: {
+          name: 'John',
+          age: 30,
+        },
+      },
+    };
+
+    await cache.set('complex', data);
+    const result = await cache.get<typeof data>('complex');
+    expect(result).toEqual(data);
+  });
+
+  it('should handle arrays', async () => {
+    const data = [1, 2, 3, 4, 5];
+    await cache.set('array', data);
+    const result = await cache.get<number[]>('array');
+    expect(result).toEqual(data);
+  });
+
+  it('should handle null values', async () => {
+    await cache.set('null-value', null);
+    const result = await cache.get('null-value');
+    expect(result).toBeNull();
+  });
+
+  it('should handle boolean values', async () => {
+    await cache.set('bool-true', true);
+    await cache.set('bool-false', false);
+
+    expect(await cache.get('bool-true')).toBe(true);
+    expect(await cache.get('bool-false')).toBe(false);
+  });
+
+  it('should handle number values', async () => {
+    await cache.set('number', 12345);
+    const result = await cache.get<number>('number');
+    expect(result).toBe(12345);
+  });
+});

tests/setup.ts

@@ -14,10 +14,12 @@ declare global {
   };
 }
 
-let db: D1Database;
+let db: D1Database | null = null;
 
 beforeAll(async () => {
-  // Miniflare 바인딩 가져오기
+  // Miniflare 바인딩 가져오기 (있을 경우만)
+  if (typeof getMiniflareBindings === 'function') {
+    try {
       const bindings = getMiniflareBindings();
       db = bindings.DB;
 
@@ -34,9 +36,16 @@ beforeAll(async () => {
       for (const statement of statements) {
         await db.exec(statement);
       }
+    } catch (error) {
+      // Miniflare 바인딩이 없는 테스트는 skip
+      console.warn('Miniflare bindings not available, skipping DB setup');
+    }
+  }
 });
 
 afterEach(async () => {
+  // DB가 있을 경우만 정리
+  if (db) {
     // 각 테스트 후 데이터 정리 (스키마는 유지)
     await db.exec('DELETE FROM deposit_transactions');
     await db.exec('DELETE FROM bank_notifications');
@@ -45,6 +54,7 @@ afterEach(async () => {
     await db.exec('DELETE FROM summaries');
     await db.exec('DELETE FROM message_buffer');
     await db.exec('DELETE FROM users');
+  }
 });
 
 /**