fix: 修復前端認證 token 發送和用戶資料隔離問題

- 啟用前端 API client 的認證 header 發送（修復關鍵問題）
- 添加 401 錯誤自動清除過期 token 機制
- 設計兩種空狀態畫面：新用戶歡迎 vs 完成慶祝
- 改進錯誤處理：區分認證錯誤和一般錯誤
- 添加詳細除錯日誌追蹤 API 調用過程
- 修復前端條件判斷邏輯，確保正確顯示空狀態

現在用戶資料完全隔離，認證過期會自動處理並引導重新登入。

🤖 Generated with [Claude Code](https://claude.ai/code)

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

backend/DramaLing.Api/Controllers/FlashcardsController.cs

@@ -5,11 +5,12 @@ using DramaLing.Api.Repositories;
 using DramaLing.Api.Services.Review;
 using Microsoft.AspNetCore.Authorization;
 using DramaLing.Api.Utils;
+using DramaLing.Api.Services;
 
 namespace DramaLing.Api.Controllers;
 
 [Route("api/flashcards")]
-[AllowAnonymous]
+[Authorize] // 恢復認證要求，確保用戶資料隔離
 public class FlashcardsController : BaseController
 {
     private readonly IFlashcardRepository _flashcardRepository;
@@ -18,7 +19,8 @@ public class FlashcardsController : BaseController
     public FlashcardsController(
         IFlashcardRepository flashcardRepository,
         IReviewService reviewService,
-        ILogger<FlashcardsController> logger) : base(logger)
+        IAuthService authService,
+        ILogger<FlashcardsController> logger) : base(logger, authService)
     {
         _flashcardRepository = flashcardRepository;
         _reviewService = reviewService;

frontend/app/review/page.tsx

@@ -23,9 +23,21 @@ export default function ReviewPage() {
     handleRestart,
     isLoading,
     error,
-    flashcards
+    flashcards,
+    totalFlashcardsCount
   } = useReviewSession()
 
+  // 除錯日誌 - 檢查狀態
+  console.log('🔍 Review Page 狀態檢查:', {
+    isLoading,
+    error,
+    flashcardsLength: flashcards.length,
+    totalFlashcardsCount,
+    currentQuizItem: currentQuizItem?.id,
+    currentCard: currentCard?.word,
+    isComplete
+  })
+
   // 顯示載入狀態
   if (isLoading) {
     return (
@@ -46,21 +58,221 @@ export default function ReviewPage() {
 
   // 顯示錯誤狀態
   if (error) {
+    const isAuthError = error.includes('登入已過期') || error.includes('認證')
+
     return (
       <div className="min-h-screen bg-gradient-to-br from-blue-50 to-indigo-100">
         <Navigation />
         <div className="py-8">
           <div className="max-w-4xl mx-auto px-4">
             <div className="bg-white rounded-xl shadow-lg p-8 text-center">
-              <div className="text-red-500 text-4xl mb-4">⚠️</div>
-              <h2 className="text-xl font-semibold text-red-700 mb-2">載入失敗</h2>
+              <div className={`text-4xl mb-4 ${isAuthError ? 'text-yellow-500' : 'text-red-500'}`}>
+                {isAuthError ? '🔒' : '⚠️'}
+              </div>
+              <h2 className={`text-xl font-semibold mb-2 ${isAuthError ? 'text-yellow-700' : 'text-red-700'}`}>
+                {isAuthError ? '需要重新登入' : '載入失敗'}
+              </h2>
               <p className="text-gray-600 mb-6">{error}</p>
+
+              <div className="flex flex-col sm:flex-row gap-3 justify-center">
+                {isAuthError ? (
+                  <button
+                    onClick={() => window.location.href = '/login'}
+                    className="px-8 py-3 bg-blue-600 text-white rounded-lg hover:bg-blue-700 transition-colors font-semibold"
+                  >
+                    前往登入
+                  </button>
+                ) : (
                   <button
                     onClick={handleRestart}
                     className="px-6 py-2 bg-blue-600 text-white rounded-lg hover:bg-blue-700 transition-colors"
                   >
                     重新載入
                   </button>
+                )}
+
+                <button
+                  onClick={() => window.location.href = '/'}
+                  className="px-6 py-2 bg-gray-600 text-white rounded-lg hover:bg-gray-700 transition-colors"
+                >
+                  回到首頁
+                </button>
+              </div>
+            </div>
+          </div>
+        </div>
+      </div>
+    )
+  }
+
+  // 情境 1: 新用戶 - 一張詞卡都沒有
+  if (!isLoading && !error && totalFlashcardsCount === 0) {
+    return (
+      <div className="min-h-screen bg-gradient-to-br from-blue-50 to-indigo-100">
+        <Navigation />
+        <div className="py-8">
+          <div className="max-w-4xl mx-auto px-4">
+            <div className="bg-white rounded-xl shadow-lg p-8 text-center">
+              {/* 歡迎圖標 */}
+              <div className="mb-6">
+                <div className="w-24 h-24 bg-gradient-to-br from-blue-400 to-blue-600 rounded-full flex items-center justify-center mx-auto mb-4">
+                  <span className="text-4xl text-white">👋</span>
+                </div>
+              </div>
+
+              {/* 歡迎標題 */}
+              <h1 className="text-3xl font-bold text-gray-900 mb-4">
+                歡迎來到 DramaLing！
+              </h1>
+
+              {/* 說明文字 */}
+              <p className="text-lg text-gray-600 mb-8">
+                開始您的英語學習之旅，建立第一張詞卡來開始學習吧！
+              </p>
+
+              {/* 功能介紹卡片 */}
+              <div className="grid grid-cols-1 md:grid-cols-2 gap-6 mb-8">
+                <div className="bg-gradient-to-br from-green-50 to-green-100 rounded-lg p-6">
+                  <div className="text-2xl text-green-600 mb-2">🎯</div>
+                  <h3 className="font-semibold text-gray-900">智能學習</h3>
+                  <p className="text-sm text-gray-600 mt-2">
+                    AI 驅動的個人化詞彙學習系統
+                  </p>
+                </div>
+
+                <div className="bg-gradient-to-br from-yellow-50 to-yellow-100 rounded-lg p-6">
+                  <div className="text-2xl text-yellow-600 mb-2">🧠</div>
+                  <h3 className="font-semibold text-gray-900">科學記憶</h3>
+                  <p className="text-sm text-gray-600 mt-2">
+                    基於遺忘曲線的複習提醒
+                  </p>
+                </div>
+              </div>
+
+              {/* 主要行動按鈕 */}
+              <div className="mb-6">
+                <button
+                  onClick={() => window.location.href = '/generate'}
+                  className="px-10 py-4 bg-gradient-to-r from-blue-600 to-blue-700 text-white rounded-lg hover:from-blue-700 hover:to-blue-800 transition-all font-semibold text-lg flex items-center justify-center gap-3 mx-auto"
+                >
+                  <span className="text-xl">🚀</span>
+                  建立第一張詞卡
+                </button>
+              </div>
+
+              {/* 次要功能 */}
+              <div className="flex flex-col sm:flex-row gap-3 justify-center">
+                <button
+                  onClick={() => window.location.href = '/flashcards'}
+                  className="px-6 py-2 bg-gray-100 text-gray-700 rounded-lg hover:bg-gray-200 transition-colors font-medium"
+                >
+                  瀏覽詞卡功能
+                </button>
+              </div>
+
+              {/* 學習提示 */}
+              <div className="mt-8 p-4 bg-blue-50 rounded-lg border border-blue-200">
+                <p className="text-sm text-blue-800">
+                  💡 <strong>開始提示</strong>: 建議從日常生活中的詞彙開始，
+                  或輸入您感興趣的英文句子讓 AI 協助分析！
+                </p>
+              </div>
+            </div>
+          </div>
+        </div>
+      </div>
+    )
+  }
+
+  // 情境 2: 有詞卡但都已訓練完成
+  if (!isLoading && !error && totalFlashcardsCount && totalFlashcardsCount > 0 && flashcards.length === 0) {
+    return (
+      <div className="min-h-screen bg-gradient-to-br from-blue-50 to-indigo-100">
+        <Navigation />
+        <div className="py-8">
+          <div className="max-w-4xl mx-auto px-4">
+            <div className="bg-white rounded-xl shadow-lg p-8 text-center">
+              {/* 慶祝圖標 */}
+              <div className="mb-6">
+                <div className="w-24 h-24 bg-gradient-to-br from-green-400 to-green-600 rounded-full flex items-center justify-center mx-auto mb-4">
+                  <span className="text-4xl text-white">🎉</span>
+                </div>
+              </div>
+
+              {/* 主要標題 */}
+              <h1 className="text-3xl font-bold text-gray-900 mb-4">
+                太棒了！所有詞卡都已掌握
+              </h1>
+
+              {/* 次標題 */}
+              <p className="text-lg text-gray-600 mb-4">
+                您已完成所有 <span className="font-semibold text-green-600">{totalFlashcardsCount}</span> 張詞卡的學習！
+              </p>
+              <p className="text-md text-gray-500 mb-8">
+                目前沒有需要複習的詞卡，您的學習進度非常優秀！
+              </p>
+
+              {/* 統計卡片 */}
+              <div className="grid grid-cols-1 md:grid-cols-3 gap-6 mb-8">
+                <div className="bg-gradient-to-br from-blue-50 to-blue-100 rounded-lg p-6">
+                  <div className="text-2xl text-blue-600 mb-2">📚</div>
+                  <h3 className="font-semibold text-gray-900">持續學習</h3>
+                  <p className="text-sm text-gray-600 mt-2">
+                    保持每日複習習慣
+                  </p>
+                </div>
+
+                <div className="bg-gradient-to-br from-purple-50 to-purple-100 rounded-lg p-6">
+                  <div className="text-2xl text-purple-600 mb-2">📈</div>
+                  <h3 className="font-semibold text-gray-900">查看進度</h3>
+                  <p className="text-sm text-gray-600 mt-2">
+                    檢視學習統計數據
+                  </p>
+                </div>
+
+                <div className="bg-gradient-to-br from-green-50 to-green-100 rounded-lg p-6">
+                  <div className="text-2xl text-green-600 mb-2">➕</div>
+                  <h3 className="font-semibold text-gray-900">擴展詞庫</h3>
+                  <p className="text-sm text-gray-600 mt-2">
+                    新增更多詞彙挑戰
+                  </p>
+                </div>
+              </div>
+
+              {/* 行動按鈕 */}
+              <div className="flex flex-col sm:flex-row gap-4 justify-center">
+                <button
+                  onClick={() => window.location.href = '/generate'}
+                  className="px-8 py-3 bg-blue-600 text-white rounded-lg hover:bg-blue-700 transition-colors font-semibold flex items-center justify-center gap-2"
+                >
+                  <span>➕</span>
+                  新增詞卡
+                </button>
+
+                <button
+                  onClick={() => window.location.href = '/stats'}
+                  className="px-8 py-3 bg-purple-600 text-white rounded-lg hover:bg-purple-700 transition-colors font-semibold flex items-center justify-center gap-2"
+                >
+                  <span>📊</span>
+                  查看統計
+                </button>
+
+                <button
+                  onClick={() => window.location.href = '/flashcards'}
+                  className="px-8 py-3 bg-gray-600 text-white rounded-lg hover:bg-gray-700 transition-colors font-semibold flex items-center justify-center gap-2"
+                >
+                  <span>📋</span>
+                  管理詞卡
+                </button>
+              </div>
+
+              {/* 提示文字 */}
+              <div className="mt-8 p-4 bg-yellow-50 rounded-lg border border-yellow-200">
+                <p className="text-sm text-yellow-800">
+                  💡 <strong>小提示</strong>: 詞卡會根據遺忘曲線算法自動安排複習時間。
+                  繼續保持學習，明天可能會有新的複習內容！
+                </p>
+              </div>
             </div>
           </div>
         </div>
@@ -108,6 +320,8 @@ export default function ReviewPage() {
   }
 
   // 主要線性測驗頁面
+  // 只有在有可用測驗項目時才顯示測驗界面
+  if (!isLoading && !error && totalFlashcardsCount !== null && totalFlashcardsCount > 0 && flashcards.length > 0 && currentQuizItem && currentCard) {
   return (
     <div className="min-h-screen bg-gradient-to-br from-blue-50 to-indigo-100">
       <Navigation />
@@ -147,4 +361,32 @@ export default function ReviewPage() {
       </div>
     </div>
   )
+  }
+
+  // Fallback 狀態 - 處理其他未預期情況
+  return (
+    <div className="min-h-screen bg-gradient-to-br from-blue-50 to-indigo-100">
+      <Navigation />
+      <div className="py-8">
+        <div className="max-w-4xl mx-auto px-4">
+          <div className="bg-white rounded-xl shadow-lg p-8 text-center">
+            <div className="text-4xl mb-4">🤔</div>
+            <h2 className="text-xl font-semibold text-gray-700 mb-2">正在準備學習內容</h2>
+            <p className="text-gray-600 mb-4">
+              系統正在載入您的學習資料，請稍候片刻。
+            </p>
+            <p className="text-sm text-gray-500 mb-6">
+              如果問題持續，請嘗試重新載入頁面。
+            </p>
+            <button
+              onClick={handleRestart}
+              className="px-6 py-2 bg-blue-600 text-white rounded-lg hover:bg-blue-700 transition-colors"
+            >
+              重新載入
+            </button>
+          </div>
+        </div>
+      </div>
+    </div>
+  )
 }

frontend/hooks/review/useReviewSession.ts

@@ -34,6 +34,7 @@ interface ReviewState {
   error: string | null
   pendingWordSubmission: string | null  // 等待提交的詞彙ID
   submittingWords: Set<string>          // 正在提交的詞彙ID集合
+  totalFlashcardsCount: number | null   // 用戶總詞卡數（用於區分空狀態）
 }
 
 type ReviewAction =
@@ -42,7 +43,7 @@ type ReviewAction =
   | { type: 'SKIP_TEST_ITEM'; payload: { quizItemId: string } }
   | { type: 'RESTART' }
   | { type: 'LOAD_FLASHCARDS_START' }
-  | { type: 'LOAD_FLASHCARDS_SUCCESS'; payload: { flashcards: Flashcard[]; quizItems: QuizItem[] } }
+  | { type: 'LOAD_FLASHCARDS_SUCCESS'; payload: { flashcards: Flashcard[]; quizItems: QuizItem[]; totalCount: number } }
   | { type: 'LOAD_FLASHCARDS_ERROR'; payload: { error: string } }
   | { type: 'WORD_SUBMIT_START'; payload: { cardId: string } }
   | { type: 'WORD_SUBMIT_SUCCESS'; payload: { cardId: string; nextReviewDate: string } }
@@ -165,7 +166,8 @@ const reviewReducer = (state: ReviewState, action: ReviewAction): ReviewState =>
         isLoading: false,
         error: null,
         flashcards: action.payload.flashcards,
-        quizItems: action.payload.quizItems
+        quizItems: action.payload.quizItems,
+        totalFlashcardsCount: action.payload.totalCount
       }
 
     case 'LOAD_FLASHCARDS_ERROR':
@@ -301,10 +303,11 @@ export function useReviewSession() {
     isLoading: false,
     error: null,
     pendingWordSubmission: null,
-    submittingWords: new Set<string>()
+    submittingWords: new Set<string>(),
+    totalFlashcardsCount: null
   })
 
-  const { quizItems, score, isComplete, flashcards, isLoading, error, pendingWordSubmission, submittingWords } = state
+  const { quizItems, score, isComplete, flashcards, isLoading, error, pendingWordSubmission, submittingWords, totalFlashcardsCount } = state
 
   // 智能排序獲取當前測驗項目 - 使用 useMemo 優化性能
   const sortedQuizItems = useMemo(() => sortQuizItemsByPriority(quizItems), [quizItems])
@@ -321,29 +324,95 @@ export function useReviewSession() {
       dispatch({ type: 'LOAD_FLASHCARDS_START' })
 
       try {
-        const response = await flashcardsService.getDueFlashcards(10)
+        console.log('🚀 開始載入詞卡資料...')
 
-        if (response.success && response.data) {
-          const flashcards = response.data
-          const quizItems = generateQuizItemsFromFlashcards(flashcards)
+        // 同時獲取待複習詞卡和總詞卡數
+        const [dueResponse, totalResponse] = await Promise.all([
+          flashcardsService.getDueFlashcards(10),
+          flashcardsService.getFlashcards() // 獲取所有詞卡來計算總數
+        ])
+
+        console.log('📥 API 回應:', {
+          dueResponse: {
+            success: dueResponse.success,
+            dataType: typeof dueResponse.data,
+            dataLength: Array.isArray(dueResponse.data) ? dueResponse.data.length : 'not array',
+            error: dueResponse.error
+          },
+          totalResponse: {
+            success: totalResponse.success,
+            dataType: typeof totalResponse.data,
+            dataLength: Array.isArray(totalResponse.data) ? totalResponse.data.length : 'not array',
+            error: totalResponse.error
+          }
+        })
+
+        if (dueResponse.success && totalResponse.success) {
+          // 正確的資料結構處理
+          const dueFlashcards = dueResponse.data || []  // getDueFlashcards 返回 Flashcard[]
+          const totalFlashcardsData = totalResponse.data || { flashcards: [], count: 0 }  // getFlashcards 返回 { flashcards: [], count: number }
+          const totalFlashcards = totalFlashcardsData.flashcards || []
+          const totalCount = totalFlashcardsData.count || totalFlashcards.length
+
+          const quizItems = generateQuizItemsFromFlashcards(dueFlashcards)
+
+          console.log('📊 資料統計:', {
+            dueFlashcards: dueFlashcards.length,
+            totalFlashcards: totalFlashcards.length,
+            totalCount: totalCount,
+            quizItems: quizItems.length
+          })
 
           dispatch({
             type: 'LOAD_FLASHCARDS_SUCCESS',
-            payload: { flashcards, quizItems }
+            payload: {
+              flashcards: dueFlashcards,
+              quizItems,
+              totalCount: totalCount
+            }
           })
 
-          console.log('✅ 成功載入', flashcards.length, '張詞卡')
+          console.log('✅ 成功載入', dueFlashcards.length, '張待複習詞卡 / 總共', totalCount, '張詞卡')
           console.log('🎯 生成', quizItems.length, '個測驗項目')
         } else {
+          console.error('❌ API 調用失敗:', {
+            dueError: dueResponse.error,
+            totalError: totalResponse.error,
+            dueSuccess: dueResponse.success,
+            totalSuccess: totalResponse.success
+          })
+
+          // 檢查是否為認證錯誤
+          const authError = dueResponse.error?.includes('登入已過期') ||
+                           totalResponse.error?.includes('登入已過期') ||
+                           dueResponse.error?.includes('認證') ||
+                           totalResponse.error?.includes('認證')
+
           dispatch({
             type: 'LOAD_FLASHCARDS_ERROR',
-            payload: { error: response.error || '載入詞卡失敗' }
+            payload: {
+              error: authError ?
+                '登入已過期，請重新登入' :
+                (dueResponse.error || totalResponse.error || '載入詞卡失敗')
+            }
           })
         }
       } catch (error) {
+        console.error('❌ API 調用異常:', error)
+
+        // 檢查是否為認證錯誤
+        const errorMessage = error instanceof Error ? error.message : '載入詞卡失敗'
+        const isAuthError = errorMessage.includes('登入已過期') ||
+                           errorMessage.includes('認證') ||
+                           errorMessage.includes('Unauthorized')
+
         dispatch({
           type: 'LOAD_FLASHCARDS_ERROR',
-          payload: { error: error instanceof Error ? error.message : '載入詞卡失敗' }
+          payload: {
+            error: isAuthError ?
+              '登入已過期，請重新登入' :
+              errorMessage
+          }
         })
       }
     }
@@ -467,6 +536,7 @@ export function useReviewSession() {
     isLoading,
     error,
     flashcards,
+    totalFlashcardsCount,
 
     // 計算屬性
     totalQuizItems: quizItems.length,

frontend/lib/api/client.ts

@@ -66,6 +66,12 @@ export class ApiClient {
           const apiError = await createApiErrorFromResponse(response, context)
           lastError = apiError
 
+          // 處理認證錯誤 - 自動清除過期token
+          if (response.status === 401) {
+            localStorage.removeItem('auth_token')
+            console.log('🔒 認證過期，已清除token')
+          }
+
           // 如果不可重試，直接返回錯誤
           if (attempt === retries || !this.isRetryableStatus(response.status)) {
             return createErrorResponse(apiError)
@@ -138,12 +144,11 @@ export class ApiClient {
   private getDefaultHeaders(): Record<string, string> {
     const headers: Record<string, string> = {}
 
-    // 開發階段：不添加認證Token
-    // TODO: 生產環境需要添加認證邏輯
-    // const token = localStorage.getItem('auth_token')
-    // if (token) {
-    //   headers.Authorization = `Bearer ${token}`
-    // }
+    // 添加認證Token（如果存在）
+    const token = localStorage.getItem('auth_token')
+    if (token) {
+      headers.Authorization = `Bearer ${token}`
+    }
 
     return headers
   }