Add Axios interceptor for automatic token refresh with mutex pattern

- api.ts: 401 응답 시 자동으로 refresh → retry, 동시 요청은 큐에 대기 (race condition 방지)
- auth-context.tsx: interceptor에 콜백 연결 (토큰 갱신/로그아웃)
- use-api.ts: 401 retry 로직 제거 (interceptor가 처리)
- build.sh: NEXT_PUBLIC 환경변수 검증 단계 추가
- CLAUDE.md: 프론트엔드 빌드 절차 추가

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -19,6 +19,8 @@
 
 - 빌드: `cd backend && export JAVA_HOME=/opt/homebrew/Cellar/openjdk/25.0.2/libexec/openjdk.jdk/Contents/Home && set -a && source ../.env && set +a && mvn package -q -DskipTests`
 - 컴파일만: `cd backend && export JAVA_HOME=/opt/homebrew/Cellar/openjdk/25.0.2/libexec/openjdk.jdk/Contents/Home && set -a && source ../.env && set +a && mvn compile`
+- 프론트엔드 빌드/배포: `cd sundol-frontend && bash build.sh` (환경변수 검증 포함)
+- 프론트엔드 빌드 전 `.env`에 `NEXT_PUBLIC_GOOGLE_CLIENT_ID`, `NEXT_PUBLIC_API_URL` 필수. 없으면 Google OAuth 로그인 깨짐.
 - 배포 시 반드시 `git push origin main` 포함
 
 # DB 접속 (Oracle Autonomous DB - SQLcl)

sundol-frontend/build.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+cd "$SCRIPT_DIR"
+
+# .env 로드
+ENV_FILE="$SCRIPT_DIR/../.env"
+if [ -f "$ENV_FILE" ]; then
+    set -a && source "$ENV_FILE" && set +a
+fi
+
+# 필수 환경변수 검증
+echo "=== [0/3] 환경변수 검증 ==="
+REQUIRED_VARS=("NEXT_PUBLIC_GOOGLE_CLIENT_ID" "NEXT_PUBLIC_API_URL")
+for var in "${REQUIRED_VARS[@]}"; do
+    if [ -z "${!var}" ]; then
+        echo "ERROR: $var 가 .env에 설정되어 있지 않습니다. 빌드를 중단합니다."
+        exit 1
+    fi
+    echo "  $var = ${!var:0:20}..."
+done
+
+echo "=== [1/3] Next.js 빌드 ==="
+npx next build
+
+echo "=== [2/3] 심볼릭 링크 생성 ==="
+STATIC_SRC="$SCRIPT_DIR/.next/static"
+STATIC_DST="$SCRIPT_DIR/.next/standalone/.next/static"
+
+if [ -L "$STATIC_DST" ] || [ -e "$STATIC_DST" ]; then
+    rm -rf "$STATIC_DST"
+fi
+
+ln -s "$STATIC_SRC" "$STATIC_DST"
+echo "링크 생성 완료: $STATIC_DST -> $STATIC_SRC"
+
+echo "=== [3/3] PM2 재시작 ==="
+pm2 restart sundol-frontend
+
+echo "=== 빌드 완료 ==="

sundol-frontend/src/lib/api.ts

@@ -1,10 +1,96 @@
-import axios from "axios";
+import axios, { AxiosError, InternalAxiosRequestConfig } from "axios";
 
 export const api = axios.create({
   baseURL: process.env.NEXT_PUBLIC_API_URL || "http://localhost:8080",
   withCredentials: true,
 });
 
+// --- 공통 토큰 refresh 로직 (mutex 패턴) ---
+
+let isRefreshing = false;
+let pendingQueue: {
+  resolve: (token: string) => void;
+  reject: (error: unknown) => void;
+}[] = [];
+
+// auth-context에서 주입하는 콜백
+let onTokenRefreshed: ((token: string) => void) | null = null;
+let onRefreshFailed: (() => void) | null = null;
+
+export function setAuthCallbacks(
+  onRefreshed: (token: string) => void,
+  onFailed: () => void
+) {
+  onTokenRefreshed = onRefreshed;
+  onRefreshFailed = onFailed;
+}
+
+function processQueue(token: string | null, error: unknown) {
+  pendingQueue.forEach(({ resolve, reject }) => {
+    if (token) {
+      resolve(token);
+    } else {
+      reject(error);
+    }
+  });
+  pendingQueue = [];
+}
+
+api.interceptors.response.use(
+  (response) => response,
+  async (error: AxiosError) => {
+    const originalRequest = error.config as InternalAxiosRequestConfig & { _retry?: boolean };
+
+    // 401이 아니거나, refresh 요청 자체가 실패한 경우, 이미 retry한 경우 → 그냥 throw
+    if (
+      error.response?.status !== 401 ||
+      originalRequest.url?.includes("/api/auth/") ||
+      originalRequest._retry
+    ) {
+      return Promise.reject(error);
+    }
+
+    // 이미 refresh 진행 중이면 큐에 대기
+    if (isRefreshing) {
+      return new Promise((resolve, reject) => {
+        pendingQueue.push({
+          resolve: (token: string) => {
+            originalRequest._retry = true;
+            originalRequest.headers["Authorization"] = `Bearer ${token}`;
+            resolve(api.request(originalRequest));
+          },
+          reject,
+        });
+      });
+    }
+
+    // refresh 시작
+    isRefreshing = true;
+    originalRequest._retry = true;
+
+    try {
+      const res = await api.post<LoginResponse>("/api/auth/refresh");
+      const newToken = res.data.accessToken;
+
+      api.defaults.headers.common["Authorization"] = `Bearer ${newToken}`;
+      onTokenRefreshed?.(newToken);
+
+      // 대기 중인 요청들 처리
+      processQueue(newToken, null);
+
+      // 원래 요청 retry
+      originalRequest.headers["Authorization"] = `Bearer ${newToken}`;
+      return api.request(originalRequest);
+    } catch (refreshError) {
+      processQueue(null, refreshError);
+      onRefreshFailed?.();
+      return Promise.reject(refreshError);
+    } finally {
+      isRefreshing = false;
+    }
+  }
+);
+
 // Types
 export interface LoginResponse {
   accessToken: string;

sundol-frontend/src/lib/auth-context.tsx

@@ -1,7 +1,7 @@
 "use client";
 
-import React, { createContext, useContext, useState, useCallback, useEffect } from "react";
-import { api, LoginResponse } from "./api";
+import React, { createContext, useContext, useState, useCallback, useEffect, useRef } from "react";
+import { api, LoginResponse, setAuthCallbacks } from "./api";
 
 interface AuthContextType {
   isAuthenticated: boolean;
@@ -24,13 +24,24 @@ const AuthContext = createContext<AuthContextType>({
 export function AuthProvider({ children }: { children: React.ReactNode }) {
   const [accessToken, setAccessToken] = useState<string | null>(null);
   const [isLoading, setIsLoading] = useState(true);
+  const logoutRef = useRef<() => void>(() => {});
+
+  // interceptor 콜백 등록
+  useEffect(() => {
+    setAuthCallbacks(
+      (token: string) => setAccessToken(token),
+      () => logoutRef.current()
+    );
+  }, []);
 
   useEffect(() => {
     // Try to restore session from refresh token cookie
     const tryRefresh = async () => {
       try {
         const res = await api.post<LoginResponse>("/api/auth/refresh");
-        setAccessToken(res.data.accessToken);
+        const token = res.data.accessToken;
+        setAccessToken(token);
+        api.defaults.headers.common["Authorization"] = `Bearer ${token}`;
       } catch {
         // No valid session
       } finally {
@@ -62,6 +73,11 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
     window.location.href = "/login";
   }, []);
 
+  // ref로 최신 logout 유지 (interceptor에서 사용)
+  useEffect(() => {
+    logoutRef.current = logout;
+  }, [logout]);
+
   return (
     <AuthContext.Provider
       value={{

sundol-frontend/src/lib/use-api.ts

@@ -1,36 +1,16 @@
 "use client";
 
 import { useCallback } from "react";
-import { api, LoginResponse } from "./api";
-import { useAuth } from "./auth-context";
-import { AxiosRequestConfig, AxiosError } from "axios";
+import { api } from "./api";
+import { AxiosRequestConfig } from "axios";
 
 export function useApi() {
-  const { setAccessToken, logout } = useAuth();
-
   const request = useCallback(
     async <T>(config: AxiosRequestConfig): Promise<T> => {
-      try {
       const response = await api.request<T>(config);
       return response.data;
-      } catch (error: unknown) {
-        const axiosError = error as AxiosError;
-        if (axiosError.response?.status === 401) {
-          try {
-            const refreshRes = await api.post<LoginResponse>("/api/auth/refresh");
-            setAccessToken(refreshRes.data.accessToken);
-            api.defaults.headers.common["Authorization"] = `Bearer ${refreshRes.data.accessToken}`;
-            const retryResponse = await api.request<T>(config);
-            return retryResponse.data;
-          } catch {
-            logout();
-            throw error;
-          }
-        }
-        throw error;
-      }
     },
-    [setAccessToken, logout]
+    []
   );
 
   return { request };