diff --git a/frontend/src/features/auth/model/AuthProvider.tsx b/frontend/src/features/auth/model/AuthProvider.tsx
index a230840..8e39667 100644
--- a/frontend/src/features/auth/model/AuthProvider.tsx
+++ b/frontend/src/features/auth/model/AuthProvider.tsx
@@ -7,7 +7,12 @@ import {
   type ReactNode,
 } from 'react'
 import { useQueryClient } from '@tanstack/react-query'
-import { isApiError, setAuthSideEffects, tokenStore } from '@/shared/api'
+import {
+  ensureAccessToken,
+  isApiError,
+  setAuthSideEffects,
+  tokenStore,
+} from '@/shared/api'
 import { fetchCurrentUser, logout as logoutApi } from '../api/auth'
 import {
   AuthContext,
@@ -83,6 +88,13 @@ export function AuthProvider({ children }: AuthProviderProps) {
 
     void (async () => {
       try {
+        // 토큰을 refresh 로 먼저 확보한 뒤 사용자 정보를 부른다.
+        // (토큰 없이 /users/me 를 쏴 401 → refresh → 재시도하던 낭비 제거)
+        const token = await ensureAccessToken()
+        if (!token) {
+          clearAuth()
+          return
+        }
         await refreshUser()
       } catch {
         clearAuth()
diff --git a/frontend/src/shared/api/client.ts b/frontend/src/shared/api/client.ts
index d3f39d2..092b1bc 100644
--- a/frontend/src/shared/api/client.ts
+++ b/frontend/src/shared/api/client.ts
@@ -120,6 +120,22 @@ function refreshOnce(): Promise<string> {
   return refreshing
 }
 
+// 앱 부트스트랩용: 토큰이 없으면 refresh 로 먼저 확보한다.
+// 이렇게 해야 첫 인증 요청(/api/users/me)이 토큰 없이 나가 401 을 유발하고
+// 재시도되는 낭비가 사라진다. 세션이 없으면(refresh 401) null 을 돌려준다.
+export async function ensureAccessToken(): Promise<string | null> {
+  const existing = tokenStore.get()
+  if (existing) return existing
+  try {
+    return await refreshOnce()
+  } catch (err) {
+    // 일시적 장애(SYS_DEPENDENCY_DOWN)는 그대로 던져 상위에서 구분 처리.
+    if (err instanceof ApiError && err.code === 'SYS_DEPENDENCY_DOWN') throw err
+    // 그 외(세션 없음 등)는 비로그인으로 취급.
+    return null
+  }
+}
+
 apiClient.interceptors.response.use(
   (response) => response,
   async (error: AxiosError<ApiErrorBody>) => {
diff --git a/frontend/src/shared/api/index.ts b/frontend/src/shared/api/index.ts
index 2edb6e5..cc9f601 100644
--- a/frontend/src/shared/api/index.ts
+++ b/frontend/src/shared/api/index.ts
@@ -1,4 +1,9 @@
-export { apiClient, setAuthSideEffects, type ApiResponse } from './client'
+export {
+  apiClient,
+  setAuthSideEffects,
+  ensureAccessToken,
+  type ApiResponse,
+} from './client'
 export { tokenStore } from './token-store'
 export {
   ApiError,
diff --git a/frontend/src/widgets/site-nav/ui/SiteNav.tsx b/frontend/src/widgets/site-nav/ui/SiteNav.tsx
index 0f91b43..059f70e 100644
--- a/frontend/src/widgets/site-nav/ui/SiteNav.tsx
+++ b/frontend/src/widgets/site-nav/ui/SiteNav.tsx
@@ -1,4 +1,4 @@
-import { useEffect, useState } from 'react'
+import { useEffect, useId, useState } from 'react'
 import { Link } from 'react-router-dom'
 import { useAuth, useLogout } from '@/features/auth'
 import { ColorModeToggle } from '@/shared/ui'
@@ -9,8 +9,38 @@ const items = [
   { to: '/#faq', label: 'FAQ' },
 ]
 
+function MenuIcon({ open }: { open: boolean }) {
+  return (
+    <svg
+      width="20"
+      height="20"
+      viewBox="0 0 24 24"
+      fill="none"
+      stroke="currentColor"
+      strokeWidth="2"
+      strokeLinecap="round"
+      aria-hidden
+    >
+      {open ? (
+        <>
+          <path d="M6 6l12 12" />
+          <path d="M18 6L6 18" />
+        </>
+      ) : (
+        <>
+          <path d="M4 7h16" />
+          <path d="M4 12h16" />
+          <path d="M4 17h16" />
+        </>
+      )}
+    </svg>
+  )
+}
+
 export function SiteNav() {
   const [scrolled, setScrolled] = useState(false)
+  const [open, setOpen] = useState(false)
+  const menuId = useId()
   const { status, user } = useAuth()
   const { logout, loggingOut } = useLogout()
 
@@ -21,11 +51,21 @@ export function SiteNav() {
     return () => window.removeEventListener('scroll', onScroll)
   }, [])
 
+  // Esc 로 닫기.
+  useEffect(() => {
+    if (!open) return
+    const onKey = (e: KeyboardEvent) => {
+      if (e.key === 'Escape') setOpen(false)
+    }
+    window.addEventListener('keydown', onKey)
+    return () => window.removeEventListener('keydown', onKey)
+  }, [open])
+
   return (
     <header
       className={[
         'sticky top-0 w-full transition-colors duration-normal ease-standard',
-        scrolled
+        scrolled || open
           ? 'border-b border-border bg-surface-raised/85 backdrop-blur-md'
           : 'border-b border-transparent bg-transparent',
       ].join(' ')}
@@ -90,8 +130,63 @@ export function SiteNav() {
               </Link>
             </>
           )}
+
+          {/* 모바일 메뉴 토글 — 데스크톱 네비/보조 링크가 숨겨지는 구간을 보완 */}
+          <button
+            type="button"
+            onClick={() => setOpen((v) => !v)}
+            aria-expanded={open}
+            aria-controls={menuId}
+            aria-label={open ? '메뉴 닫기' : '메뉴 열기'}
+            className="inline-flex h-9 w-9 items-center justify-center rounded-md text-fg-muted transition-colors duration-fast hover:text-fg-strong md:hidden"
+          >
+            <MenuIcon open={open} />
+          </button>
         </div>
       </div>
+
+      {/* 모바일 드롭다운 메뉴 */}
+      {open ? (
+        <nav
+          id={menuId}
+          aria-label="Mobile"
+          className="border-t border-border bg-surface-raised/95 backdrop-blur-md md:hidden"
+        >
+          <div className="mx-auto flex max-w-content flex-col gap-1 px-6 py-3">
+            {items.map((it) => (
+              <Link
+                key={it.to}
+                to={it.to}
+                onClick={() => setOpen(false)}
+                className="rounded-md px-3 py-2.5 text-button text-fg-muted transition-colors duration-fast hover:bg-surface hover:text-fg-strong"
+              >
+                {it.label}
+              </Link>
+            ))}
+            <div className="my-1 h-px bg-border" />
+            {status === 'authenticated' ? (
+              <Link
+                to="/workspace"
+                onClick={() => setOpen(false)}
+                className="flex items-center gap-2 rounded-md px-3 py-2.5 text-button text-fg-strong transition-colors duration-fast hover:bg-surface"
+              >
+                {user?.avatarUrl ? (
+                  <img src={user.avatarUrl} alt="" aria-hidden className="h-6 w-6 rounded-full" />
+                ) : null}
+                <span>{user?.displayName ?? '워크스페이스'}</span>
+              </Link>
+            ) : (
+              <Link
+                to="/login"
+                onClick={() => setOpen(false)}
+                className="rounded-md px-3 py-2.5 text-button text-fg-strong transition-colors duration-fast hover:bg-surface"
+              >
+                로그인
+              </Link>
+            )}
+          </div>
+        </nav>
+      ) : null}
     </header>
   )
 }