diff --git a/backend/DramaLing.Api/Controllers/BaseController.cs b/backend/DramaLing.Api/Controllers/BaseController.cs
new file mode 100644
index 0000000..5b13cd3
--- /dev/null
+++ b/backend/DramaLing.Api/Controllers/BaseController.cs
@@ -0,0 +1,157 @@
+using Microsoft.AspNetCore.Mvc;
+using DramaLing.Api.Models.DTOs;
+using DramaLing.Api.Services;
+using System.Security.Claims;
+
+namespace DramaLing.Api.Controllers;
+
+[ApiController]
+public abstract class BaseController : ControllerBase
+{
+    protected readonly ILogger _logger;
+    protected readonly IAuthService? _authService;
+
+    protected BaseController(ILogger logger, IAuthService? authService = null)
+    {
+        _logger = logger;
+        _authService = authService;
+    }
+
+    /// <summary>
+    /// 統一的成功響應格式
+    /// </summary>
+    protected IActionResult SuccessResponse<T>(T data, string? message = null)
+    {
+        return Ok(new ApiResponse<T>
+        {
+            Success = true,
+            Data = data,
+            Message = message,
+            Timestamp = DateTime.UtcNow
+        });
+    }
+
+    /// <summary>
+    /// 統一的錯誤響應格式
+    /// </summary>
+    protected IActionResult ErrorResponse(string code, string message, object? details = null, int statusCode = 500)
+    {
+        var response = new ApiErrorResponse
+        {
+            Success = false,
+            Error = new ApiError
+            {
+                Code = code,
+                Message = message,
+                Details = details,
+                Suggestions = GetSuggestionsForError(code)
+            },
+            RequestId = Guid.NewGuid().ToString(),
+            Timestamp = DateTime.UtcNow
+        };
+
+        return StatusCode(statusCode, response);
+    }
+
+    /// <summary>
+    /// 獲取當前用戶ID（統一處理認證）
+    /// </summary>
+    protected async Task<Guid> GetCurrentUserIdAsync()
+    {
+        if (_authService != null)
+        {
+            // 使用AuthService進行JWT解析（適用於已實現認證的Controller）
+            var userId = await _authService.GetUserIdFromTokenAsync(Request.Headers.Authorization);
+            if (userId.HasValue)
+                return userId.Value;
+        }
+
+        // Fallback: 從Claims直接解析
+        var userIdString = User.FindFirst(ClaimTypes.NameIdentifier)?.Value ??
+                          User.FindFirst("sub")?.Value;
+
+        if (Guid.TryParse(userIdString, out var parsedUserId))
+            return parsedUserId;
+
+        // 開發階段：使用固定測試用戶ID
+        if (IsTestEnvironment())
+        {
+            return Guid.Parse("00000000-0000-0000-0000-000000000001");
+        }
+
+        throw new UnauthorizedAccessException("Invalid or missing user authentication");
+    }
+
+    /// <summary>
+    /// 檢查是否為測試環境
+    /// </summary>
+    protected bool IsTestEnvironment()
+    {
+        var environment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");
+        return environment == "Development" || environment == "Testing";
+    }
+
+    /// <summary>
+    /// 統一的模型驗證錯誤處理
+    /// </summary>
+    protected IActionResult HandleModelStateErrors()
+    {
+        var errors = ModelState
+            .Where(x => x.Value?.Errors.Count > 0)
+            .ToDictionary(
+                kvp => kvp.Key,
+                kvp => kvp.Value?.Errors.Select(e => e.ErrorMessage).ToArray() ?? Array.Empty<string>()
+            );
+
+        return ErrorResponse("VALIDATION_ERROR", "輸入資料驗證失敗", errors, 400);
+    }
+
+    /// <summary>
+    /// 根據錯誤代碼獲取建議
+    /// </summary>
+    private List<string> GetSuggestionsForError(string errorCode)
+    {
+        return errorCode switch
+        {
+            "VALIDATION_ERROR" => new List<string> { "請檢查輸入格式", "確保所有必填欄位已填寫" },
+            "INVALID_INPUT" => new List<string> { "請檢查輸入格式", "確保文本長度在限制內" },
+            "RATE_LIMIT_EXCEEDED" => new List<string> { "升級到Premium帳戶以獲得無限使用", "明天重新嘗試" },
+            "AI_SERVICE_ERROR" => new List<string> { "請稍後重試", "如果問題持續，請聯繫客服" },
+            "UNAUTHORIZED" => new List<string> { "請檢查登入狀態", "確認Token是否有效" },
+            "NOT_FOUND" => new List<string> { "請檢查資源ID是否正確", "確認資源是否存在" },
+            _ => new List<string> { "請稍後重試", "如果問題持續，請聯繫客服" }
+        };
+    }
+}
+
+/// <summary>
+/// 統一API響應格式
+/// </summary>
+public class ApiResponse<T>
+{
+    public bool Success { get; set; } = true;
+    public T? Data { get; set; }
+    public string? Message { get; set; }
+    public DateTime Timestamp { get; set; } = DateTime.UtcNow;
+}
+
+/// <summary>
+/// 分頁響應格式
+/// </summary>
+public class PagedApiResponse<T> : ApiResponse<List<T>>
+{
+    public PaginationMetadata Pagination { get; set; } = new();
+}
+
+/// <summary>
+/// 分頁元數據
+/// </summary>
+public class PaginationMetadata
+{
+    public int CurrentPage { get; set; }
+    public int PageSize { get; set; }
+    public int TotalCount { get; set; }
+    public int TotalPages { get; set; }
+    public bool HasNext { get; set; }
+    public bool HasPrevious { get; set; }
+}
\ No newline at end of file
diff --git a/backend/DramaLing.Api/Controllers/FlashcardsController.cs b/backend/DramaLing.Api/Controllers/FlashcardsController.cs
index 00d2aa1..d1f8841 100644
--- a/backend/DramaLing.Api/Controllers/FlashcardsController.cs
+++ b/backend/DramaLing.Api/Controllers/FlashcardsController.cs
@@ -5,75 +5,73 @@ using Microsoft.AspNetCore.Authorization;
 
 namespace DramaLing.Api.Controllers;
 
-[ApiController]
 [Route("api/flashcards")]
 [AllowAnonymous]
-public class FlashcardsController : ControllerBase
+public class FlashcardsController : BaseController
 {
     private readonly IFlashcardRepository _flashcardRepository;
-    private readonly ILogger<FlashcardsController> _logger;
 
     public FlashcardsController(
         IFlashcardRepository flashcardRepository,
-        ILogger<FlashcardsController> logger)
+        ILogger<FlashcardsController> logger) : base(logger)
     {
         _flashcardRepository = flashcardRepository;
-        _logger = logger;
-    }
-
-    private Guid GetUserId()
-    {
-        // 暫時使用固定測試用戶 ID
-        return Guid.Parse("00000000-0000-0000-0000-000000000001");
     }
 
     [HttpGet]
-    public async Task<ActionResult> GetFlashcards(
+    public async Task<IActionResult> GetFlashcards(
         [FromQuery] string? search = null,
         [FromQuery] bool favoritesOnly = false)
     {
         try
         {
-            var userId = GetUserId();
+            var userId = await GetCurrentUserIdAsync();
             var flashcards = await _flashcardRepository.GetByUserIdAsync(userId, search, favoritesOnly);
 
-            return Ok(new
+            var flashcardData = new
             {
-                Success = true,
-                Data = new
+                Flashcards = flashcards.Select(f => new
                 {
-                    Flashcards = flashcards.Select(f => new
-                    {
-                        f.Id,
-                        f.Word,
-                        f.Translation,
-                        f.Definition,
-                        f.PartOfSpeech,
-                        f.Pronunciation,
-                        f.Example,
-                        f.ExampleTranslation,
-                        f.IsFavorite,
-                        f.DifficultyLevel,
-                        f.CreatedAt,
-                        f.UpdatedAt
-                    }),
-                    Count = flashcards.Count()
-                }
-            });
+                    f.Id,
+                    f.Word,
+                    f.Translation,
+                    f.Definition,
+                    f.PartOfSpeech,
+                    f.Pronunciation,
+                    f.Example,
+                    f.ExampleTranslation,
+                    f.IsFavorite,
+                    f.DifficultyLevel,
+                    f.CreatedAt,
+                    f.UpdatedAt
+                }),
+                Count = flashcards.Count()
+            };
+
+            return SuccessResponse(flashcardData);
+        }
+        catch (UnauthorizedAccessException)
+        {
+            return ErrorResponse("UNAUTHORIZED", "認證失敗", null, 401);
         }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Error getting flashcards");
-            return StatusCode(500, new { Success = false, Error = "Failed to load flashcards" });
+            return ErrorResponse("INTERNAL_ERROR", "載入詞卡失敗");
         }
     }
 
     [HttpPost]
-    public async Task<ActionResult> CreateFlashcard([FromBody] CreateFlashcardRequest request)
+    public async Task<IActionResult> CreateFlashcard([FromBody] CreateFlashcardRequest request)
     {
         try
         {
-            var userId = GetUserId();
+            if (!ModelState.IsValid)
+            {
+                return HandleModelStateErrors();
+            }
+
+            var userId = await GetCurrentUserIdAsync();
 
             var flashcard = new Flashcard
             {
@@ -93,55 +91,63 @@ public class FlashcardsController : ControllerBase
 
             await _flashcardRepository.AddAsync(flashcard);
 
-            return Ok(new
-            {
-                Success = true,
-                Data = flashcard,
-                Message = "詞卡創建成功"
-            });
+            return SuccessResponse(flashcard, "詞卡創建成功");
+        }
+        catch (UnauthorizedAccessException)
+        {
+            return ErrorResponse("UNAUTHORIZED", "認證失敗", null, 401);
         }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Error creating flashcard");
-            return StatusCode(500, new { Success = false, Error = "Failed to create flashcard" });
+            return ErrorResponse("INTERNAL_ERROR", "創建詞卡失敗");
         }
     }
 
     [HttpGet("{id}")]
-    public async Task<ActionResult> GetFlashcard(Guid id)
+    public async Task<IActionResult> GetFlashcard(Guid id)
     {
         try
         {
-            var userId = GetUserId();
+            var userId = await GetCurrentUserIdAsync();
 
             var flashcard = await _flashcardRepository.GetByUserIdAndFlashcardIdAsync(userId, id);
 
             if (flashcard == null)
             {
-                return NotFound(new { Success = false, Error = "Flashcard not found" });
+                return ErrorResponse("NOT_FOUND", "詞卡不存在", null, 404);
             }
 
-            return Ok(new { Success = true, Data = flashcard });
+            return SuccessResponse(flashcard);
+        }
+        catch (UnauthorizedAccessException)
+        {
+            return ErrorResponse("UNAUTHORIZED", "認證失敗", null, 401);
         }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Error getting flashcard {FlashcardId}", id);
-            return StatusCode(500, new { Success = false, Error = "Failed to get flashcard" });
+            return ErrorResponse("INTERNAL_ERROR", "取得詞卡失敗");
         }
     }
 
     [HttpPut("{id}")]
-    public async Task<ActionResult> UpdateFlashcard(Guid id, [FromBody] CreateFlashcardRequest request)
+    public async Task<IActionResult> UpdateFlashcard(Guid id, [FromBody] CreateFlashcardRequest request)
     {
         try
         {
-            var userId = GetUserId();
+            if (!ModelState.IsValid)
+            {
+                return HandleModelStateErrors();
+            }
+
+            var userId = await GetCurrentUserIdAsync();
 
             var flashcard = await _flashcardRepository.GetByUserIdAndFlashcardIdAsync(userId, id);
 
             if (flashcard == null)
             {
-                return NotFound(new { Success = false, Error = "Flashcard not found" });
+                return ErrorResponse("NOT_FOUND", "詞卡不存在", null, 404);
             }
 
             // 更新詞卡資訊
@@ -156,57 +162,60 @@ public class FlashcardsController : ControllerBase
 
             await _flashcardRepository.UpdateAsync(flashcard);
 
-            return Ok(new
-            {
-                Success = true,
-                Data = flashcard,
-                Message = "詞卡更新成功"
-            });
+            return SuccessResponse(flashcard, "詞卡更新成功");
+        }
+        catch (UnauthorizedAccessException)
+        {
+            return ErrorResponse("UNAUTHORIZED", "認證失敗", null, 401);
         }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Error updating flashcard {FlashcardId}", id);
-            return StatusCode(500, new { Success = false, Error = "Failed to update flashcard" });
+            return ErrorResponse("INTERNAL_ERROR", "更新詞卡失敗");
         }
     }
 
     [HttpDelete("{id}")]
-    public async Task<ActionResult> DeleteFlashcard(Guid id)
+    public async Task<IActionResult> DeleteFlashcard(Guid id)
     {
         try
         {
-            var userId = GetUserId();
+            var userId = await GetCurrentUserIdAsync();
 
             var flashcard = await _flashcardRepository.GetByUserIdAndFlashcardIdAsync(userId, id);
 
             if (flashcard == null)
             {
-                return NotFound(new { Success = false, Error = "Flashcard not found" });
+                return ErrorResponse("NOT_FOUND", "詞卡不存在", null, 404);
             }
 
             await _flashcardRepository.DeleteAsync(flashcard);
 
-            return Ok(new { Success = true, Message = "詞卡已刪除" });
+            return SuccessResponse(new { Id = id }, "詞卡已刪除");
+        }
+        catch (UnauthorizedAccessException)
+        {
+            return ErrorResponse("UNAUTHORIZED", "認證失敗", null, 401);
         }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Error deleting flashcard {FlashcardId}", id);
-            return StatusCode(500, new { Success = false, Error = "Failed to delete flashcard" });
+            return ErrorResponse("INTERNAL_ERROR", "刪除詞卡失敗");
         }
     }
 
     [HttpPost("{id}/favorite")]
-    public async Task<ActionResult> ToggleFavorite(Guid id)
+    public async Task<IActionResult> ToggleFavorite(Guid id)
     {
         try
         {
-            var userId = GetUserId();
+            var userId = await GetCurrentUserIdAsync();
 
             var flashcard = await _flashcardRepository.GetByUserIdAndFlashcardIdAsync(userId, id);
 
             if (flashcard == null)
             {
-                return NotFound(new { Success = false, Error = "Flashcard not found" });
+                return ErrorResponse("NOT_FOUND", "詞卡不存在", null, 404);
             }
 
             flashcard.IsFavorite = !flashcard.IsFavorite;
@@ -214,16 +223,22 @@ public class FlashcardsController : ControllerBase
 
             await _flashcardRepository.UpdateAsync(flashcard);
 
-            return Ok(new {
-                Success = true,
-                IsFavorite = flashcard.IsFavorite,
-                Message = flashcard.IsFavorite ? "已加入收藏" : "已取消收藏"
-            });
+            var result = new {
+                Id = flashcard.Id,
+                IsFavorite = flashcard.IsFavorite
+            };
+
+            var message = flashcard.IsFavorite ? "已加入收藏" : "已取消收藏";
+            return SuccessResponse(result, message);
+        }
+        catch (UnauthorizedAccessException)
+        {
+            return ErrorResponse("UNAUTHORIZED", "認證失敗", null, 401);
         }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Error toggling favorite for flashcard {FlashcardId}", id);
-            return StatusCode(500, new { Success = false, Error = "Failed to toggle favorite" });
+            return ErrorResponse("INTERNAL_ERROR", "切換收藏狀態失敗");
         }
     }
 }
diff --git a/backend/DramaLing.Api/DramaLing.Api.csproj b/backend/DramaLing.Api/DramaLing.Api.csproj
index 4ed5f7e..c0d1354 100644
--- a/backend/DramaLing.Api/DramaLing.Api.csproj
+++ b/backend/DramaLing.Api/DramaLing.Api.csproj
@@ -24,4 +24,8 @@
     <PackageReference Include="Microsoft.Extensions.Diagnostics.HealthChecks" Version="8.0.10" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Compile Remove="DramaLing.Api.Tests/**/*.cs" />
+  </ItemGroup>
+
 </Project>
\ No newline at end of file
diff --git a/backend/DramaLing.Api/Models/Configuration/GeminiOptionsValidator.cs b/backend/DramaLing.Api/Models/Configuration/GeminiOptionsValidator.cs
index fb6a323..bd0536a 100644
--- a/backend/DramaLing.Api/Models/Configuration/GeminiOptionsValidator.cs
+++ b/backend/DramaLing.Api/Models/Configuration/GeminiOptionsValidator.cs
@@ -5,7 +5,7 @@ namespace DramaLing.Api.Models.Configuration;
 
 public class GeminiOptionsValidator : IValidateOptions<GeminiOptions>
 {
-    public ValidateOptionsResult Validate(string name, GeminiOptions options)
+    public ValidateOptionsResult Validate(string? name, GeminiOptions options)
     {
         var failures = new List<string>();
 
diff --git a/backend/DramaLing.Api/Program.cs b/backend/DramaLing.Api/Program.cs
index 37ebeeb..ac7f499 100644
--- a/backend/DramaLing.Api/Program.cs
+++ b/backend/DramaLing.Api/Program.cs
@@ -1,13 +1,13 @@
 using Microsoft.EntityFrameworkCore;
 using DramaLing.Api.Data;
 using DramaLing.Api.Services;
-// Services.AI namespace removed
 using DramaLing.Api.Services.Caching;
 using DramaLing.Api.Services.Monitoring;
 using DramaLing.Api.Services.Storage;
 using DramaLing.Api.Middleware;
 using DramaLing.Api.Models.Configuration;
 using DramaLing.Api.Repositories;
+using DramaLing.Api.Extensions;
 using Microsoft.AspNetCore.Authentication.JwtBearer;
 using Microsoft.IdentityModel.Tokens;
 using Microsoft.Extensions.Options;
@@ -49,51 +49,16 @@ builder.Services.AddControllers()
         options.JsonSerializerOptions.WriteIndented = true;
     });
 
-// Entity Framework - 使用 SQLite 進行測試
-var useInMemoryDb = Environment.GetEnvironmentVariable("USE_INMEMORY_DB") == "true";
-if (useInMemoryDb)
-{
-    builder.Services.AddDbContext<DramaLingDbContext>(options =>
-        options.UseSqlite("Data Source=:memory:"));
-}
-else
-{
-    var connectionString = Environment.GetEnvironmentVariable("DRAMALING_DB_CONNECTION")
-        ?? builder.Configuration.GetConnectionString("DefaultConnection")
-        ?? "Data Source=dramaling_test.db"; // SQLite 檔案
+// 配置資料庫服務
+builder.Services.AddDatabaseServices(builder.Configuration);
 
-    builder.Services.AddDbContext<DramaLingDbContext>(options =>
-        options.UseSqlite(connectionString));
-}
+// 配置 Repository 和 Caching 服務
+builder.Services.AddRepositoryServices();
+builder.Services.AddCachingServices();
 
-// 暫時註解新的服務，等修正編譯錯誤後再啟用
-// Repository Services
-// builder.Services.AddScoped(typeof(IRepository<>), typeof(BaseRepository<>));
-// builder.Services.AddScoped<IFlashcardRepository, SimpleFlashcardRepository>();
-// builder.Services.AddScoped<IUserRepository, UserRepository>();
-
-// Caching Services - now using Extension method
-// builder.Services.AddMemoryCache();
-// builder.Services.AddScoped<ICacheService, HybridCacheService>();
-
-// AI Services
-// builder.Services.AddHttpClient<GeminiAIProvider>();
-// builder.Services.AddScoped<IAIProvider, GeminiAIProvider>();
-// builder.Services.AddScoped<IAIProviderManager, AIProviderManager>();
-
-// Custom Services
-builder.Services.AddScoped<IAuthService, AuthService>();
-builder.Services.AddHttpClient<IGeminiService, GeminiService>();
-// 新增帶快取的分析服務
-builder.Services.AddScoped<IAnalysisService, AnalysisService>();
-builder.Services.AddScoped<IUsageTrackingService, UsageTrackingService>();
-builder.Services.AddScoped<IAzureSpeechService, AzureSpeechService>();
-// 智能填空題系統服務已移除
-builder.Services.AddScoped<IAudioCacheService, AudioCacheService>();
-
-// 智能複習服務已移除，準備重新實施
-
-// 學習會話服務已清理移除
+// 配置 AI 和業務服務
+builder.Services.AddAIServices(builder.Configuration);
+builder.Services.AddBusinessServices();
 
 // 🆕 選項詞彙庫服務註冊
 builder.Services.Configure<OptionsVocabularyOptions>(
@@ -103,15 +68,7 @@ builder.Services.AddSingleton<OptionsVocabularyMetrics>(); // 監控指標服務
 // builder.Services.AddScoped<OptionsVocabularySeeder>(); // 暫時註解，使用固定選項
 builder.Services.AddScoped<IOptionsVocabularyService, OptionsVocabularyService>();
 
-// Image Generation Services
-builder.Services.AddHttpClient<IReplicateService, ReplicateService>();
-builder.Services.AddScoped<IImageGenerationOrchestrator, ImageGenerationOrchestrator>();
-
-// Image Storage Services
-builder.Services.AddScoped<IImageStorageService, LocalImageStorageService>();
-
-// Image Processing Services
-builder.Services.AddScoped<IImageProcessingService, ImageProcessingService>();
+// (圖片相關服務已透過 AddAIServices 和 AddBusinessServices 註冊)
 
 // Background Services (快取清理服務已移除)