diff --git a/app/citizen-frontend/src/main.ts b/app/citizen-frontend/src/main.ts
index 082ecfe..dd7266e 100644
--- a/app/citizen-frontend/src/main.ts
+++ b/app/citizen-frontend/src/main.ts
@@ -9,6 +9,7 @@ import { createApp } from "vue";
 
 // Plugins
 import { registerPlugins } from "@/plugins";
+import { useAppStore } from "@/stores/app";
 
 // Components
 import App from "./App.vue";
@@ -20,4 +21,10 @@ const app = createApp(App);
 
 registerPlugins(app);
 
-app.mount("#app");
+async function bootstrap() {
+  const store = useAppStore();
+  await store.initializeAuthentication();
+  app.mount("#app");
+}
+
+void bootstrap();
diff --git a/app/citizen-frontend/src/pages/profile.vue b/app/citizen-frontend/src/pages/profile.vue
index d3f4907..d720bd8 100644
--- a/app/citizen-frontend/src/pages/profile.vue
+++ b/app/citizen-frontend/src/pages/profile.vue
@@ -6,8 +6,8 @@
           <v-card-title class="text-primary font-weight-bold"
             >個人資料修改</v-card-title
           >
-          <v-card-subtitle class="text-grey-darken-3"
-            >更新您的基本資料與緊急聯絡資訊。</v-card-subtitle
+          <v-card-subtitle class="text-grey-darken-3">
+            更新您的基本資料與緊急聯絡資訊。</v-card-subtitle
           >
         </v-card>
 
@@ -59,7 +59,7 @@
                 icon="mdi-lock-outline"
                 variant="tonal"
               >
-                手機門號不可由個人資料修改
+                手機門號不可自行修改
               </v-alert>
 
               <v-text-field
diff --git a/app/citizen-frontend/src/pages/self-assessment.vue b/app/citizen-frontend/src/pages/self-assessment.vue
index e2814d1..27a7ccc 100644
--- a/app/citizen-frontend/src/pages/self-assessment.vue
+++ b/app/citizen-frontend/src/pages/self-assessment.vue
@@ -513,7 +513,7 @@
 </template>
 
 <script setup lang="ts">
-import { computed, onMounted, reactive, ref } from "vue";
+import { computed, onMounted, reactive, ref, watch } from "vue";
 import { useRouter } from "vue-router";
 import type {
   ChronicDisease,
@@ -687,16 +687,25 @@ function scrollToPageTop() {
   window.scrollTo({ top: 0 });
 }
 
+function clearErrorMessage() {
+  errorMessage.value = "";
+}
+
 function goToPreviousStep() {
+  clearErrorMessage();
   currentStep.value -= 1;
   scrollToPageTop();
 }
 
 function goToNextStep() {
+  clearErrorMessage();
   currentStep.value += 1;
   scrollToPageTop();
 }
 
+watch(profileForm, clearErrorMessage);
+watch(assessmentForm, clearErrorMessage);
+
 function buildAssessmentRequest(): SelfAssessmentRequest | null {
   if (
     !profileForm.name.trim() ||
diff --git a/app/citizen-frontend/src/router/index.ts b/app/citizen-frontend/src/router/index.ts
index d041a34..4a605f9 100644
--- a/app/citizen-frontend/src/router/index.ts
+++ b/app/citizen-frontend/src/router/index.ts
@@ -78,8 +78,9 @@ const router = createRouter({
 });
 
 // 簡單的導航守衛：只有標記需要登入的頁面會導向登入頁
-router.beforeEach((to) => {
+router.beforeEach(async (to) => {
   const store = useAppStore();
+  await store.initializeAuthentication();
 
   if (to.meta.requiresAuth && !store.isLoggedIn) {
     return {
@@ -99,9 +100,10 @@ if (typeof window !== "undefined") {
   window.addEventListener("auth-expired", () => {
     const store = useAppStore();
     const currentRoute = router.currentRoute.value;
+    const wasLoggedIn = store.isLoggedIn;
     store.clearAuthentication();
 
-    if (currentRoute.name !== "login") {
+    if (wasLoggedIn && currentRoute.name !== "login") {
       void router.replace({
         name: "login",
         query: { redirect: currentRoute.fullPath },
diff --git a/app/citizen-frontend/src/stores/app.ts b/app/citizen-frontend/src/stores/app.ts
index 9eeded0..6fe5b3c 100644
--- a/app/citizen-frontend/src/stores/app.ts
+++ b/app/citizen-frontend/src/stores/app.ts
@@ -317,6 +317,8 @@ function createDefaultRadarData() {
 
 export const useAppStore = defineStore("app", () => {
   const isLoggedIn = ref(false);
+  const isAuthInitialized = ref(false);
+  let authInitializationPromise: Promise<boolean> | null = null;
   /** 僅供前端顯示或其他使用者資料用途；course/group 不再傳送此值。 */
   const userID = ref("");
   const userProfile = ref<UserProfile>(createEmptyUserProfile());
@@ -368,6 +370,37 @@ export const useAppStore = defineStore("app", () => {
     };
   }
 
+  /** 以 HttpOnly Cookie 還原頁面重新整理後的登入狀態。 */
+  async function initializeAuthentication(): Promise<boolean> {
+    if (isAuthInitialized.value) {
+      return isLoggedIn.value;
+    }
+
+    if (authInitializationPromise) {
+      return authInitializationPromise;
+    }
+
+    authInitializationPromise = (async () => {
+      try {
+        if (!USE_MOCK) {
+          const profile = await apiGetProfile();
+          isLoggedIn.value = true;
+          userProfile.value = applyProfileToStore(profile);
+        }
+
+        return isLoggedIn.value;
+      } catch {
+        // 未登入時 profile API 會回 401，維持訪客狀態即可。
+        clearAuthentication();
+        return false;
+      } finally {
+        isAuthInitialized.value = true;
+      }
+    })();
+
+    return authInitializationPromise;
+  }
+
   /** 使用手機門號與密碼登入，成功後只保存非敏感的回應資料。 */
   async function login(phone: string, password: string): Promise<AuthResponse> {
     if (!password) {
@@ -666,6 +699,7 @@ export const useAppStore = defineStore("app", () => {
 
   return {
     isLoggedIn,
+    isAuthInitialized,
     userID,
     userProfile,
     selfAssessment,
@@ -679,6 +713,7 @@ export const useAppStore = defineStore("app", () => {
     progressPercent,
     login,
     register,
+    initializeAuthentication,
     logout,
     clearAuthentication,
     updateProfile,