diff --git a/DATABASE_NAMING_CONVENTION_PLAN.md b/DATABASE_NAMING_CONVENTION_PLAN.md
new file mode 100644
index 0000000..2569f19
--- /dev/null
+++ b/DATABASE_NAMING_CONVENTION_PLAN.md
@@ -0,0 +1,213 @@
+# 資料庫命名規範統一計劃
+
+## 📋 計劃概述
+
+本計劃旨在解決 DramaLing 專案中資料庫欄位命名不一致的問題，將所有資料庫欄位統一為 `snake_case` 命名規範。
+
+## 🔍 現況分析
+
+### 問題描述
+目前資料庫中同時存在兩種命名方式：
+- **PascalCase**: `Example`, `Word`, `Translation`, `Definition`, `Name`, `Color` 等
+- **snake_case**: `user_id`, `created_at`, `is_favorite`, `part_of_speech` 等
+
+### 問題根源
+1. **歷史遺留**: 早期遷移沒有統一配置欄位命名
+2. **不完整配置**: 部分屬性缺少 `.HasColumnName()` 映射
+3. **維護疏漏**: 新增欄位時沒有遵循統一規範
+
+### 已修復項目 ✅
+- ✅ `Flashcard.Word` → `word`
+- ✅ `Flashcard.Translation` → `translation`
+- ✅ `Flashcard.Definition` → `definition`
+- ✅ `Flashcard.Pronunciation` → `pronunciation`
+- ✅ `Flashcard.Example` → `example` (原始問題)
+
+## 🎯 統一規範標準
+
+### 命名規則
+| 層級 | 命名方式 | 範例 | 說明 |
+|------|----------|------|------|
+| **C# 實體屬性** | PascalCase | `UserId`, `CreatedAt`, `ExampleTranslation` | 符合 C# 慣例 |
+| **資料庫欄位** | snake_case | `user_id`, `created_at`, `example_translation` | 符合資料庫慣例 |
+| **表格名稱** | snake_case | `flashcards`, `user_profiles`, `daily_stats` | 保持一致性 |
+
+### 映射規則
+```csharp
+// 所有屬性都需要明確映射
+entity.Property(e => e.PropertyName).HasColumnName("property_name");
+```
+
+## 📝 待修復項目清單
+
+### 1. Tag 實體
+```csharp
+// 目前缺少的映射：
+public Guid Id { get; set; }           // → "id"
+public string Name { get; set; }       // → "name"
+public string Color { get; set; }      // → "color"
+```
+
+### 2. ErrorReport 實體
+```csharp
+// 目前缺少的映射：
+public Guid Id { get; set; }           // → "id"
+public string? Description { get; set; } // → "description"
+public string Status { get; set; }     // → "status"
+```
+
+### 3. DailyStats 實體
+```csharp
+// 目前缺少的映射：
+public Guid Id { get; set; }           // → "id"
+public DateTime Date { get; set; }     // → "date"
+```
+
+### 4. 其他實體
+需要檢查以下實體是否有遺漏的映射：
+- `SentenceAnalysisCache`
+- `WordQueryUsageStats`
+- `ExampleImage`
+- `ImageGenerationRequest`
+- `OptionsVocabulary`
+
+### 5. 通用 Id 欄位
+所有實體的 `Id` 屬性都應該映射為 `id`
+
+## 🚀 執行步驟
+
+### 階段一：DbContext 配置更新
+1. **補充 Tag 實體配置**
+   ```csharp
+   private void ConfigureTagEntities(ModelBuilder modelBuilder)
+   {
+       var tagEntity = modelBuilder.Entity<Tag>();
+       tagEntity.Property(t => t.Id).HasColumnName("id");
+       tagEntity.Property(t => t.Name).HasColumnName("name");
+       tagEntity.Property(t => t.Color).HasColumnName("color");
+       // 其他現有配置...
+   }
+   ```
+
+2. **補充其他實體配置**
+   - 更新 `ConfigureErrorReportEntity`
+   - 更新 `ConfigureDailyStatsEntity`
+   - 新增其他實體的配置方法
+
+### 階段二：資料庫遷移
+1. **建立遷移**
+   ```bash
+   dotnet ef migrations add CompleteSnakeCaseNaming
+   ```
+
+2. **套用遷移**
+   ```bash
+   dotnet ef database update
+   ```
+
+### 階段三：驗證與測試
+1. **檢查資料庫結構**
+   ```sql
+   .schema table_name
+   ```
+
+2. **測試應用程式功能**
+   - API 端點測試
+   - 資料查詢測試
+   - 完整功能驗證
+
+## 📋 檢核清單
+
+### 配置檢核
+- [ ] 所有實體的 `Id` 屬性都有 `.HasColumnName("id")`
+- [ ] 所有多單字屬性都使用 snake_case（如 `CreatedAt` → `created_at`）
+- [ ] 所有布林屬性都使用 `is_` 前綴（如 `IsActive` → `is_active`）
+- [ ] 外鍵屬性都使用 `_id` 後綴（如 `UserId` → `user_id`）
+
+### 遷移檢核
+- [ ] 遷移檔案正確生成
+- [ ] SQL 指令正確（RENAME COLUMN）
+- [ ] 沒有資料遺失風險
+- [ ] 回滾計劃準備完成
+
+### 測試檢核
+- [ ] 所有 API 端點正常運作
+- [ ] 資料查詢結果正確
+- [ ] 無效能退化
+- [ ] 前端功能正常
+
+## 🔧 長期維護建議
+
+### 1. 編碼規範
+建立明確的編碼規範文檔：
+```markdown
+## 資料庫命名規範
+- 所有新增的實體屬性都必須配置 `.HasColumnName()`
+- 資料庫欄位名稱統一使用 snake_case
+- 布林欄位使用 `is_` 前綴
+- 外鍵欄位使用 `_id` 後綴
+```
+
+### 2. Code Review 檢查點
+在 PR 審查時檢查：
+- 新增實體是否有完整的欄位映射配置
+- 遷移檔案是否符合命名規範
+- 是否需要更新相關文檔
+
+### 3. 自動化檢查
+考慮實施：
+- **Pre-commit Hook**: 檢查新增的 DbContext 配置
+- **CI/CD 檢查**: 驗證遷移檔案的正確性
+- **單元測試**: 確保所有實體都有正確的欄位映射
+
+### 4. 全局慣例配置（進階選項）
+可以考慮使用 EF Core 的全局慣例：
+```csharp
+protected override void ConfigureConventions(ModelConfigurationBuilder configurationBuilder)
+{
+    configurationBuilder.Properties<string>()
+        .HaveColumnName(propertyInfo => propertyInfo.Name.ToSnakeCase());
+}
+```
+
+## 📊 影響評估
+
+### 優點
+- ✅ 統一的命名規範
+- ✅ 更好的可維護性
+- ✅ 避免開發混淆
+- ✅ 符合業界標準
+
+### 風險
+- ⚠️ 需要資料庫遷移
+- ⚠️ 可能影響現有查詢
+- ⚠️ 需要充分測試
+
+### 緩解措施
+- 📋 充分的測試計劃
+- 🔄 準備回滾方案
+- 📝 詳細的變更文檔
+- 👥 團隊溝通協調
+
+## 🗓️ 執行時間表
+
+| 階段 | 預估時間 | 責任人 | 狀態 |
+|------|----------|--------|------|
+| 現況分析 | 0.5 天 | 開發團隊 | ✅ 完成 |
+| 配置更新 | 1 天 | 後端開發 | 🚧 進行中 |
+| 遷移建立 | 0.5 天 | 後端開發 | ⏳ 待執行 |
+| 測試驗證 | 1 天 | 全團隊 | ⏳ 待執行 |
+| 部署上線 | 0.5 天 | DevOps | ⏳ 待執行 |
+
+## 📞 聯絡資訊
+
+如有問題或需要協助，請聯絡：
+- **技術負責人**: [待填入]
+- **專案經理**: [待填入]
+- **QA 負責人**: [待填入]
+
+---
+
+**文件版本**: v1.0
+**最後更新**: 2025-09-30
+**建立人**: Claude Code Assistant
\ No newline at end of file
diff --git a/backend/DramaLing.Api/Controllers/AIController.cs b/backend/DramaLing.Api/Controllers/AIController.cs
index 578fad9..f5870dd 100644
--- a/backend/DramaLing.Api/Controllers/AIController.cs
+++ b/backend/DramaLing.Api/Controllers/AIController.cs
@@ -6,19 +6,16 @@ using System.Diagnostics;
 
 namespace DramaLing.Api.Controllers;
 
-[ApiController]
 [Route("api/ai")]
-public class AIController : ControllerBase
+public class AIController : BaseController
 {
     private readonly IAnalysisService _analysisService;
-    private readonly ILogger<AIController> _logger;
 
     public AIController(
         IAnalysisService analysisService,
-        ILogger<AIController> logger)
+        ILogger<AIController> logger) : base(logger)
     {
         _analysisService = analysisService;
-        _logger = logger;
     }
 
     /// <summary>
@@ -28,7 +25,7 @@ public class AIController : ControllerBase
     /// <returns>分析結果</returns>
     [HttpPost("analyze-sentence")]
     [AllowAnonymous]
-    public async Task<ActionResult<SentenceAnalysisResponse>> AnalyzeSentence(
+    public async Task<IActionResult> AnalyzeSentence(
         [FromBody] SentenceAnalysisRequest request)
     {
         var requestId = Guid.NewGuid().ToString();
@@ -45,9 +42,7 @@ public class AIController : ControllerBase
             // Input validation
             if (!ModelState.IsValid)
             {
-                return BadRequest(CreateErrorResponse("INVALID_INPUT", "輸入格式錯誤",
-                    ModelState.Values.SelectMany(v => v.Errors).Select(e => e.ErrorMessage).ToList(),
-                    requestId));
+                return HandleModelStateErrors();
             }
 
             // 使用帶快取的分析服務
@@ -61,27 +56,29 @@ public class AIController : ControllerBase
             _logger.LogInformation("Sentence analysis completed for request {RequestId} in {ElapsedMs}ms",
                 requestId, stopwatch.ElapsedMilliseconds);
 
-            return Ok(new SentenceAnalysisResponse
+            var response = new SentenceAnalysisResponse
             {
                 Success = true,
                 ProcessingTime = stopwatch.Elapsed.TotalSeconds,
                 Data = analysisData
-            });
+            };
+
+            return SuccessResponse(response);
         }
         catch (ArgumentException ex)
         {
             _logger.LogWarning(ex, "Invalid input for request {RequestId}", requestId);
-            return BadRequest(CreateErrorResponse("INVALID_INPUT", ex.Message, null, requestId));
+            return ErrorResponse("INVALID_INPUT", ex.Message, null, 400);
         }
         catch (InvalidOperationException ex)
         {
             _logger.LogError(ex, "AI service error for request {RequestId}", requestId);
-            return StatusCode(500, CreateErrorResponse("AI_SERVICE_ERROR", "AI服務暫時不可用", null, requestId));
+            return ErrorResponse("AI_SERVICE_ERROR", "AI服務暫時不可用", null, 500);
         }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Unexpected error processing request {RequestId}", requestId);
-            return StatusCode(500, CreateErrorResponse("INTERNAL_ERROR", "伺服器內部錯誤", null, requestId));
+            return ErrorResponse("INTERNAL_ERROR", "伺服器內部錯誤", null, 500);
         }
     }
 
@@ -90,15 +87,17 @@ public class AIController : ControllerBase
     /// </summary>
     [HttpGet("health")]
     [AllowAnonymous]
-    public ActionResult GetHealth()
+    public IActionResult GetHealth()
     {
-        return Ok(new
+        var healthData = new
         {
             Status = "Healthy",
             Service = "AI Analysis Service",
             Timestamp = DateTime.UtcNow,
             Version = "1.0"
-        });
+        };
+
+        return SuccessResponse(healthData);
     }
 
     /// <summary>
@@ -106,59 +105,28 @@ public class AIController : ControllerBase
     /// </summary>
     [HttpGet("stats")]
     [AllowAnonymous]
-    public async Task<ActionResult> GetAnalysisStats()
+    public async Task<IActionResult> GetAnalysisStats()
     {
         try
         {
             var stats = await _analysisService.GetAnalysisStatsAsync();
-            return Ok(new
+            var statsData = new
             {
-                Success = true,
-                Data = new
-                {
-                    TotalAnalyses = stats.TotalAnalyses,
-                    CachedAnalyses = stats.CachedAnalyses,
-                    CacheHitRate = stats.CacheHitRate,
-                    AverageResponseTimeMs = stats.AverageResponseTimeMs,
-                    LastAnalysisAt = stats.LastAnalysisAt,
-                    ProviderUsage = stats.ProviderUsageStats
-                }
-            });
+                TotalAnalyses = stats.TotalAnalyses,
+                CachedAnalyses = stats.CachedAnalyses,
+                CacheHitRate = stats.CacheHitRate,
+                AverageResponseTimeMs = stats.AverageResponseTimeMs,
+                LastAnalysisAt = stats.LastAnalysisAt,
+                ProviderUsage = stats.ProviderUsageStats
+            };
+
+            return SuccessResponse(statsData);
         }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Error getting analysis stats");
-            return StatusCode(500, new { Success = false, Error = "無法取得統計資訊" });
+            return ErrorResponse("INTERNAL_ERROR", "無法取得統計資訊");
         }
     }
 
-    private ApiErrorResponse CreateErrorResponse(string code, string message, object? details, string requestId)
-    {
-        var suggestions = GetSuggestionsForError(code);
-
-        return new ApiErrorResponse
-        {
-            Success = false,
-            Error = new ApiError
-            {
-                Code = code,
-                Message = message,
-                Details = details,
-                Suggestions = suggestions
-            },
-            RequestId = requestId,
-            Timestamp = DateTime.UtcNow
-        };
-    }
-
-    private List<string> GetSuggestionsForError(string errorCode)
-    {
-        return errorCode switch
-        {
-            "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" },
-            _ => new List<string> { "請稍後重試" }
-        };
-    }
 }
\ No newline at end of file
diff --git a/backend/DramaLing.Api/Controllers/AnalysisController.cs b/backend/DramaLing.Api/Controllers/AnalysisController.cs
new file mode 100644
index 0000000..e8d7b4f
--- /dev/null
+++ b/backend/DramaLing.Api/Controllers/AnalysisController.cs
@@ -0,0 +1,124 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Authorization;
+using DramaLing.Api.Models.DTOs;
+using DramaLing.Api.Services;
+using System.Diagnostics;
+
+namespace DramaLing.Api.Controllers;
+
+[Route("api/analysis")]
+[AllowAnonymous]
+public class AnalysisController : BaseController
+{
+    private readonly IAnalysisService _analysisService;
+
+    public AnalysisController(
+        IAnalysisService analysisService,
+        ILogger<AnalysisController> logger) : base(logger)
+    {
+        _analysisService = analysisService;
+    }
+
+    /// <summary>
+    /// 智能分析英文句子
+    /// </summary>
+    /// <param name="request">分析請求</param>
+    /// <returns>分析結果</returns>
+    [HttpPost("analyze")]
+    public async Task<IActionResult> AnalyzeSentence([FromBody] SentenceAnalysisRequest request)
+    {
+        var requestId = Guid.NewGuid().ToString();
+        var stopwatch = Stopwatch.StartNew();
+
+        try
+        {
+            // Input validation
+            if (!ModelState.IsValid)
+            {
+                return HandleModelStateErrors();
+            }
+
+            _logger.LogInformation("Processing sentence analysis request {RequestId}", requestId);
+
+            // 使用帶快取的分析服務
+            var options = request.Options ?? new AnalysisOptions();
+            var analysisData = await _analysisService.AnalyzeSentenceAsync(
+                request.InputText, options);
+
+            stopwatch.Stop();
+            analysisData.Metadata.ProcessingDate = DateTime.UtcNow;
+
+            _logger.LogInformation("Sentence analysis completed for request {RequestId} in {ElapsedMs}ms",
+                requestId, stopwatch.ElapsedMilliseconds);
+
+            var response = new SentenceAnalysisResponse
+            {
+                Success = true,
+                ProcessingTime = stopwatch.Elapsed.TotalSeconds,
+                Data = analysisData
+            };
+
+            return SuccessResponse(response);
+        }
+        catch (ArgumentException ex)
+        {
+            _logger.LogWarning(ex, "Invalid input for request {RequestId}", requestId);
+            return ErrorResponse("INVALID_INPUT", ex.Message, null, 400);
+        }
+        catch (InvalidOperationException ex)
+        {
+            _logger.LogError(ex, "AI service error for request {RequestId}", requestId);
+            return ErrorResponse("AI_SERVICE_ERROR", "AI服務暫時不可用", null, 500);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Unexpected error processing request {RequestId}", requestId);
+            return ErrorResponse("INTERNAL_ERROR", "伺服器內部錯誤", null, 500);
+        }
+    }
+
+    /// <summary>
+    /// 健康檢查端點
+    /// </summary>
+    [HttpGet("health")]
+    public IActionResult GetHealth()
+    {
+        var healthData = new
+        {
+            Status = "Healthy",
+            Service = "Analysis Service",
+            Timestamp = DateTime.UtcNow,
+            Version = "1.0"
+        };
+
+        return SuccessResponse(healthData);
+    }
+
+    /// <summary>
+    /// 取得分析統計資訊
+    /// </summary>
+    [HttpGet("stats")]
+    public async Task<IActionResult> GetAnalysisStats()
+    {
+        try
+        {
+            var stats = await _analysisService.GetAnalysisStatsAsync();
+            var statsData = new
+            {
+                TotalAnalyses = stats.TotalAnalyses,
+                CachedAnalyses = stats.CachedAnalyses,
+                CacheHitRate = stats.CacheHitRate,
+                AverageResponseTimeMs = stats.AverageResponseTimeMs,
+                LastAnalysisAt = stats.LastAnalysisAt,
+                ProviderUsage = stats.ProviderUsageStats
+            };
+
+            return SuccessResponse(statsData);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Error getting analysis stats");
+            return ErrorResponse("INTERNAL_ERROR", "無法取得統計資訊");
+        }
+    }
+}
\ No newline at end of file
diff --git a/backend/DramaLing.Api/Controllers/AudioController.cs b/backend/DramaLing.Api/Controllers/AudioController.cs
index d21cabc..132733e 100644
--- a/backend/DramaLing.Api/Controllers/AudioController.cs
+++ b/backend/DramaLing.Api/Controllers/AudioController.cs
@@ -5,23 +5,20 @@ using DramaLing.Api.Services;
 
 namespace DramaLing.Api.Controllers;
 
-[ApiController]
 [Route("api/[controller]")]
 [Authorize]
-public class AudioController : ControllerBase
+public class AudioController : BaseController
 {
     private readonly IAudioCacheService _audioCacheService;
     private readonly IAzureSpeechService _speechService;
-    private readonly ILogger<AudioController> _logger;
 
     public AudioController(
         IAudioCacheService audioCacheService,
         IAzureSpeechService speechService,
-        ILogger<AudioController> logger)
+        ILogger<AudioController> logger) : base(logger)
     {
         _audioCacheService = audioCacheService;
         _speechService = speechService;
-        _logger = logger;
     }
 
     /// <summary>
@@ -30,7 +27,7 @@ public class AudioController : ControllerBase
     /// <param name="request">TTS request parameters</param>
     /// <returns>Audio URL and metadata</returns>
     [HttpPost("tts")]
-    public async Task<ActionResult<TTSResponse>> GenerateAudio([FromBody] TTSRequest request)
+    public async Task<IActionResult> GenerateAudio([FromBody] TTSRequest request)
     {
         try
         {
@@ -70,10 +67,10 @@ public class AudioController : ControllerBase
 
             if (!string.IsNullOrEmpty(response.Error))
             {
-                return StatusCode(500, response);
+                return ErrorResponse("TTS_ERROR", response.Error, null, 500);
             }
 
-            return Ok(response);
+            return SuccessResponse(response);
         }
         catch (Exception ex)
         {
diff --git a/backend/DramaLing.Api/Controllers/AuthController.cs b/backend/DramaLing.Api/Controllers/AuthController.cs
index 6a75910..3af6944 100644
--- a/backend/DramaLing.Api/Controllers/AuthController.cs
+++ b/backend/DramaLing.Api/Controllers/AuthController.cs
@@ -12,26 +12,21 @@ using Microsoft.IdentityModel.Tokens;
 
 namespace DramaLing.Api.Controllers;
 
-[ApiController]
 [Route("api/[controller]")]
-public class AuthController : ControllerBase
+public class AuthController : BaseController
 {
     private readonly DramaLingDbContext _context;
-    private readonly IAuthService _authService;
-    private readonly ILogger<AuthController> _logger;
 
     public AuthController(
         DramaLingDbContext context,
         IAuthService authService,
-        ILogger<AuthController> logger)
+        ILogger<AuthController> logger) : base(logger, authService)
     {
         _context = context;
-        _authService = authService;
-        _logger = logger;
     }
 
     [HttpPost("register")]
-    public async Task<ActionResult> Register([FromBody] RegisterRequest request)
+    public async Task<IActionResult> Register([FromBody] RegisterRequest request)
     {
         try
         {
diff --git a/backend/DramaLing.Api/Controllers/ImageGenerationController.cs b/backend/DramaLing.Api/Controllers/ImageGenerationController.cs
index b8dc3de..81f0aa2 100644
--- a/backend/DramaLing.Api/Controllers/ImageGenerationController.cs
+++ b/backend/DramaLing.Api/Controllers/ImageGenerationController.cs
@@ -7,19 +7,16 @@ using System.Security.Claims;
 namespace DramaLing.Api.Controllers;
 
 [Route("api/[controller]")]
-[ApiController]
 [AllowAnonymous]  // 暫時移除認證要求，與 FlashcardsController 保持一致
-public class ImageGenerationController : ControllerBase
+public class ImageGenerationController : BaseController
 {
     private readonly IImageGenerationOrchestrator _orchestrator;
-    private readonly ILogger<ImageGenerationController> _logger;
 
     public ImageGenerationController(
         IImageGenerationOrchestrator orchestrator,
-        ILogger<ImageGenerationController> logger)
+        ILogger<ImageGenerationController> logger) : base(logger)
     {
         _orchestrator = orchestrator ?? throw new ArgumentNullException(nameof(orchestrator));
-        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
     }
 
     /// <summary>
@@ -43,17 +40,17 @@ public class ImageGenerationController : ControllerBase
 
             var result = await _orchestrator.StartGenerationAsync(flashcardId, request);
 
-            return Ok(new { success = true, data = result });
+            return SuccessResponse(result);
         }
         catch (ArgumentException ex)
         {
             _logger.LogWarning(ex, "Invalid request for flashcard {FlashcardId}", flashcardId);
-            return BadRequest(new { success = false, error = ex.Message });
+            return ErrorResponse("INVALID_REQUEST", ex.Message, null, 400);
         }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Failed to start image generation for flashcard {FlashcardId}", flashcardId);
-            return StatusCode(500, new { success = false, error = "Failed to start generation" });
+            return ErrorResponse("GENERATION_FAILED", "Failed to start generation");
         }
     }
 
@@ -73,17 +70,17 @@ public class ImageGenerationController : ControllerBase
 
             var status = await _orchestrator.GetGenerationStatusAsync(requestId);
 
-            return Ok(new { success = true, data = status });
+            return SuccessResponse(status);
         }
         catch (ArgumentException ex)
         {
             _logger.LogWarning(ex, "Generation request {RequestId} not found", requestId);
-            return NotFound(new { success = false, error = ex.Message });
+            return ErrorResponse("NOT_FOUND", ex.Message, null, 404);
         }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Failed to get status for request {RequestId}", requestId);
-            return StatusCode(500, new { success = false, error = "Failed to get status" });
+            return ErrorResponse("STATUS_ERROR", "Failed to get status");
         }
     }
 
@@ -105,17 +102,17 @@ public class ImageGenerationController : ControllerBase
 
             if (cancelled)
             {
-                return Ok(new { success = true, message = "Generation cancelled successfully" });
+                return SuccessResponse(new { message = "Generation cancelled successfully" });
             }
             else
             {
-                return BadRequest(new { success = false, error = "Cannot cancel this request" });
+                return ErrorResponse("CANCEL_FAILED", "Cannot cancel this request", null, 400);
             }
         }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Failed to cancel generation request {RequestId}", requestId);
-            return StatusCode(500, new { success = false, error = "Failed to cancel generation" });
+            return ErrorResponse("CANCEL_ERROR", "Failed to cancel generation");
         }
     }
 
@@ -148,12 +145,12 @@ public class ImageGenerationController : ControllerBase
                 }
             };
 
-            return Ok(new { success = true, data = history });
+            return SuccessResponse(history);
         }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Failed to get generation history for user");
-            return StatusCode(500, new { success = false, error = "Failed to get history" });
+            return ErrorResponse("HISTORY_ERROR", "Failed to get history");
         }
     }
 
diff --git a/backend/DramaLing.Api/Controllers/OptionsVocabularyTestController.cs b/backend/DramaLing.Api/Controllers/OptionsVocabularyTestController.cs
index 07eeacc..7e793a2 100644
--- a/backend/DramaLing.Api/Controllers/OptionsVocabularyTestController.cs
+++ b/backend/DramaLing.Api/Controllers/OptionsVocabularyTestController.cs
@@ -6,19 +6,16 @@ namespace DramaLing.Api.Controllers;
 /// <summary>
 /// 選項詞彙庫服務測試控制器 (僅用於開發測試)
 /// </summary>
-[ApiController]
 [Route("api/test/[controller]")]
-public class OptionsVocabularyTestController : ControllerBase
+public class OptionsVocabularyTestController : BaseController
 {
     private readonly IOptionsVocabularyService _optionsVocabularyService;
-    private readonly ILogger<OptionsVocabularyTestController> _logger;
 
     public OptionsVocabularyTestController(
         IOptionsVocabularyService optionsVocabularyService,
-        ILogger<OptionsVocabularyTestController> logger)
+        ILogger<OptionsVocabularyTestController> logger) : base(logger)
     {
         _optionsVocabularyService = optionsVocabularyService;
-        _logger = logger;
     }
 
     /// <summary>
diff --git a/backend/DramaLing.Api/Controllers/StatsController.cs b/backend/DramaLing.Api/Controllers/StatsController.cs
index b5a6dc3..9cb7445 100644
--- a/backend/DramaLing.Api/Controllers/StatsController.cs
+++ b/backend/DramaLing.Api/Controllers/StatsController.cs
@@ -6,14 +6,13 @@ using System.Security.Claims;
 
 namespace DramaLing.Api.Controllers;
 
-[ApiController]
 [Route("api/[controller]")]
 [Authorize]
-public class StatsController : ControllerBase
+public class StatsController : BaseController
 {
     private readonly DramaLingDbContext _context;
 
-    public StatsController(DramaLingDbContext context)
+    public StatsController(DramaLingDbContext context, ILogger<StatsController> logger) : base(logger)
     {
         _context = context;
     }
diff --git a/backend/DramaLing.Api/Data/DramaLingDbContext.cs b/backend/DramaLing.Api/Data/DramaLingDbContext.cs
index e55740a..f91ec61 100644
--- a/backend/DramaLing.Api/Data/DramaLingDbContext.cs
+++ b/backend/DramaLing.Api/Data/DramaLingDbContext.cs
@@ -49,14 +49,19 @@ public class DramaLingDbContext : DbContext
         modelBuilder.Entity<FlashcardExampleImage>().ToTable("flashcard_example_images");
         modelBuilder.Entity<ImageGenerationRequest>().ToTable("image_generation_requests");
         modelBuilder.Entity<OptionsVocabulary>().ToTable("options_vocabularies");
+        modelBuilder.Entity<SentenceAnalysisCache>().ToTable("sentence_analysis_cache");
+        modelBuilder.Entity<WordQueryUsageStats>().ToTable("word_query_usage_stats");
 
         // 配置屬性名稱 (snake_case)
         ConfigureUserEntity(modelBuilder);
+        ConfigureUserSettingsEntity(modelBuilder);
         ConfigureFlashcardEntity(modelBuilder);
         // ConfigureStudyEntities 已移除 - StudyRecord 實體已清理
         ConfigureTagEntities(modelBuilder);
         ConfigureErrorReportEntity(modelBuilder);
         ConfigureDailyStatsEntity(modelBuilder);
+        ConfigureSentenceAnalysisCacheEntity(modelBuilder);
+        ConfigureWordQueryUsageStatsEntity(modelBuilder);
         ConfigureAudioEntities(modelBuilder);
         ConfigureImageGenerationEntities(modelBuilder);
         ConfigureOptionsVocabularyEntity(modelBuilder);
@@ -79,6 +84,7 @@ public class DramaLingDbContext : DbContext
     private void ConfigureUserEntity(ModelBuilder modelBuilder)
     {
         var userEntity = modelBuilder.Entity<User>();
+        userEntity.Property(u => u.Id).HasColumnName("id");
         userEntity.Property(u => u.Username).HasColumnName("username");
         userEntity.Property(u => u.Email).HasColumnName("email");
         userEntity.Property(u => u.PasswordHash).HasColumnName("password_hash");
@@ -108,8 +114,14 @@ public class DramaLingDbContext : DbContext
     private void ConfigureFlashcardEntity(ModelBuilder modelBuilder)
     {
         var flashcardEntity = modelBuilder.Entity<Flashcard>();
+        flashcardEntity.Property(f => f.Id).HasColumnName("id");
         flashcardEntity.Property(f => f.UserId).HasColumnName("user_id");
+        flashcardEntity.Property(f => f.Word).HasColumnName("word");
+        flashcardEntity.Property(f => f.Translation).HasColumnName("translation");
+        flashcardEntity.Property(f => f.Definition).HasColumnName("definition");
         flashcardEntity.Property(f => f.PartOfSpeech).HasColumnName("part_of_speech");
+        flashcardEntity.Property(f => f.Pronunciation).HasColumnName("pronunciation");
+        flashcardEntity.Property(f => f.Example).HasColumnName("example");
         flashcardEntity.Property(f => f.ExampleTranslation).HasColumnName("example_translation");
         // 已刪除的復習相關屬性配置
         // EasinessFactor, IntervalDays, NextReviewDate, MasteryLevel,
@@ -126,7 +138,10 @@ public class DramaLingDbContext : DbContext
     private void ConfigureTagEntities(ModelBuilder modelBuilder)
     {
         var tagEntity = modelBuilder.Entity<Tag>();
+        tagEntity.Property(t => t.Id).HasColumnName("id");
         tagEntity.Property(t => t.UserId).HasColumnName("user_id");
+        tagEntity.Property(t => t.Name).HasColumnName("name");
+        tagEntity.Property(t => t.Color).HasColumnName("color");
         tagEntity.Property(t => t.UsageCount).HasColumnName("usage_count");
         tagEntity.Property(t => t.CreatedAt).HasColumnName("created_at");
 
@@ -138,10 +153,13 @@ public class DramaLingDbContext : DbContext
     private void ConfigureErrorReportEntity(ModelBuilder modelBuilder)
     {
         var errorEntity = modelBuilder.Entity<ErrorReport>();
+        errorEntity.Property(e => e.Id).HasColumnName("id");
         errorEntity.Property(e => e.UserId).HasColumnName("user_id");
         errorEntity.Property(e => e.FlashcardId).HasColumnName("flashcard_id");
         errorEntity.Property(e => e.ReportType).HasColumnName("report_type");
+        errorEntity.Property(e => e.Description).HasColumnName("description");
         errorEntity.Property(e => e.StudyMode).HasColumnName("study_mode");
+        errorEntity.Property(e => e.Status).HasColumnName("status");
         errorEntity.Property(e => e.AdminNotes).HasColumnName("admin_notes");
         errorEntity.Property(e => e.ResolvedAt).HasColumnName("resolved_at");
         errorEntity.Property(e => e.ResolvedBy).HasColumnName("resolved_by");
@@ -151,7 +169,9 @@ public class DramaLingDbContext : DbContext
     private void ConfigureDailyStatsEntity(ModelBuilder modelBuilder)
     {
         var statsEntity = modelBuilder.Entity<DailyStats>();
+        statsEntity.Property(d => d.Id).HasColumnName("id");
         statsEntity.Property(d => d.UserId).HasColumnName("user_id");
+        statsEntity.Property(d => d.Date).HasColumnName("date");
         statsEntity.Property(d => d.WordsStudied).HasColumnName("words_studied");
         statsEntity.Property(d => d.WordsCorrect).HasColumnName("words_correct");
         statsEntity.Property(d => d.StudyTimeSeconds).HasColumnName("study_time_seconds");
@@ -161,6 +181,54 @@ public class DramaLingDbContext : DbContext
         statsEntity.Property(d => d.CreatedAt).HasColumnName("created_at");
     }
 
+    private void ConfigureUserSettingsEntity(ModelBuilder modelBuilder)
+    {
+        var settingsEntity = modelBuilder.Entity<UserSettings>();
+        settingsEntity.Property(us => us.Id).HasColumnName("id");
+        settingsEntity.Property(us => us.UserId).HasColumnName("user_id");
+        settingsEntity.Property(us => us.DailyGoal).HasColumnName("daily_goal");
+        settingsEntity.Property(us => us.ReminderTime).HasColumnName("reminder_time");
+        settingsEntity.Property(us => us.ReminderEnabled).HasColumnName("reminder_enabled");
+        settingsEntity.Property(us => us.DifficultyPreference).HasColumnName("difficulty_preference");
+        settingsEntity.Property(us => us.AutoPlayAudio).HasColumnName("auto_play_audio");
+        settingsEntity.Property(us => us.ShowPronunciation).HasColumnName("show_pronunciation");
+        settingsEntity.Property(us => us.CreatedAt).HasColumnName("created_at");
+        settingsEntity.Property(us => us.UpdatedAt).HasColumnName("updated_at");
+    }
+
+    private void ConfigureSentenceAnalysisCacheEntity(ModelBuilder modelBuilder)
+    {
+        var cacheEntity = modelBuilder.Entity<SentenceAnalysisCache>();
+        cacheEntity.Property(sac => sac.Id).HasColumnName("id");
+        cacheEntity.Property(sac => sac.InputTextHash).HasColumnName("input_text_hash");
+        cacheEntity.Property(sac => sac.InputText).HasColumnName("input_text");
+        cacheEntity.Property(sac => sac.CorrectedText).HasColumnName("corrected_text");
+        cacheEntity.Property(sac => sac.HasGrammarErrors).HasColumnName("has_grammar_errors");
+        cacheEntity.Property(sac => sac.GrammarCorrections).HasColumnName("grammar_corrections");
+        cacheEntity.Property(sac => sac.AnalysisResult).HasColumnName("analysis_result");
+        cacheEntity.Property(sac => sac.HighValueWords).HasColumnName("high_value_words");
+        cacheEntity.Property(sac => sac.IdiomsDetected).HasColumnName("idioms_detected");
+        cacheEntity.Property(sac => sac.CreatedAt).HasColumnName("created_at");
+        cacheEntity.Property(sac => sac.ExpiresAt).HasColumnName("expires_at");
+        cacheEntity.Property(sac => sac.AccessCount).HasColumnName("access_count");
+        cacheEntity.Property(sac => sac.LastAccessedAt).HasColumnName("last_accessed_at");
+    }
+
+    private void ConfigureWordQueryUsageStatsEntity(ModelBuilder modelBuilder)
+    {
+        var statsEntity = modelBuilder.Entity<WordQueryUsageStats>();
+        statsEntity.Property(wq => wq.Id).HasColumnName("id");
+        statsEntity.Property(wq => wq.UserId).HasColumnName("user_id");
+        statsEntity.Property(wq => wq.Date).HasColumnName("date");
+        statsEntity.Property(wq => wq.SentenceAnalysisCount).HasColumnName("sentence_analysis_count");
+        statsEntity.Property(wq => wq.HighValueWordClicks).HasColumnName("high_value_word_clicks");
+        statsEntity.Property(wq => wq.LowValueWordClicks).HasColumnName("low_value_word_clicks");
+        statsEntity.Property(wq => wq.TotalApiCalls).HasColumnName("total_api_calls");
+        statsEntity.Property(wq => wq.UniqueWordsQueried).HasColumnName("unique_words_queried");
+        statsEntity.Property(wq => wq.CreatedAt).HasColumnName("created_at");
+        statsEntity.Property(wq => wq.UpdatedAt).HasColumnName("updated_at");
+    }
+
     private void ConfigureRelationships(ModelBuilder modelBuilder)
     {
         // User relationships
@@ -255,8 +323,10 @@ public class DramaLingDbContext : DbContext
     {
         // AudioCache configuration
         var audioCacheEntity = modelBuilder.Entity<AudioCache>();
+        audioCacheEntity.Property(ac => ac.Id).HasColumnName("id");
         audioCacheEntity.Property(ac => ac.TextHash).HasColumnName("text_hash");
         audioCacheEntity.Property(ac => ac.TextContent).HasColumnName("text_content");
+        audioCacheEntity.Property(ac => ac.Accent).HasColumnName("accent");
         audioCacheEntity.Property(ac => ac.VoiceId).HasColumnName("voice_id");
         audioCacheEntity.Property(ac => ac.AudioUrl).HasColumnName("audio_url");
         audioCacheEntity.Property(ac => ac.FileSize).HasColumnName("file_size");
@@ -274,6 +344,7 @@ public class DramaLingDbContext : DbContext
 
         // PronunciationAssessment configuration
         var pronunciationEntity = modelBuilder.Entity<PronunciationAssessment>();
+        pronunciationEntity.Property(pa => pa.Id).HasColumnName("id");
         pronunciationEntity.Property(pa => pa.UserId).HasColumnName("user_id");
         pronunciationEntity.Property(pa => pa.FlashcardId).HasColumnName("flashcard_id");
         pronunciationEntity.Property(pa => pa.TargetText).HasColumnName("target_text");
@@ -296,6 +367,7 @@ public class DramaLingDbContext : DbContext
 
         // UserAudioPreferences configuration
         var audioPrefsEntity = modelBuilder.Entity<UserAudioPreferences>();
+        audioPrefsEntity.Property(uap => uap.UserId).HasColumnName("user_id");
         audioPrefsEntity.Property(uap => uap.PreferredAccent).HasColumnName("preferred_accent");
         audioPrefsEntity.Property(uap => uap.PreferredVoiceMale).HasColumnName("preferred_voice_male");
         audioPrefsEntity.Property(uap => uap.PreferredVoiceFemale).HasColumnName("preferred_voice_female");
@@ -336,6 +408,7 @@ public class DramaLingDbContext : DbContext
     {
         // ExampleImage configuration
         var exampleImageEntity = modelBuilder.Entity<ExampleImage>();
+        exampleImageEntity.Property(ei => ei.Id).HasColumnName("id");
         exampleImageEntity.Property(ei => ei.RelativePath).HasColumnName("relative_path");
         exampleImageEntity.Property(ei => ei.AltText).HasColumnName("alt_text");
         exampleImageEntity.Property(ei => ei.GeminiPrompt).HasColumnName("gemini_prompt");
@@ -371,6 +444,7 @@ public class DramaLingDbContext : DbContext
 
         // ImageGenerationRequest configuration
         var generationRequestEntity = modelBuilder.Entity<ImageGenerationRequest>();
+        generationRequestEntity.Property(igr => igr.Id).HasColumnName("id");
         generationRequestEntity.Property(igr => igr.UserId).HasColumnName("user_id");
         generationRequestEntity.Property(igr => igr.FlashcardId).HasColumnName("flashcard_id");
         generationRequestEntity.Property(igr => igr.OverallStatus).HasColumnName("overall_status");
@@ -433,6 +507,8 @@ public class DramaLingDbContext : DbContext
         var optionsVocabEntity = modelBuilder.Entity<OptionsVocabulary>();
 
         // Configure column names (snake_case)
+        optionsVocabEntity.Property(ov => ov.Id).HasColumnName("id");
+        optionsVocabEntity.Property(ov => ov.Word).HasColumnName("word");
         optionsVocabEntity.Property(ov => ov.CEFRLevel).HasColumnName("cefr_level");
         optionsVocabEntity.Property(ov => ov.PartOfSpeech).HasColumnName("part_of_speech");
         optionsVocabEntity.Property(ov => ov.WordLength).HasColumnName("word_length");
diff --git a/backend/DramaLing.Api/Extensions/ServiceCollectionExtensions.cs b/backend/DramaLing.Api/Extensions/ServiceCollectionExtensions.cs
index 7fa62b5..1dbb05b 100644
--- a/backend/DramaLing.Api/Extensions/ServiceCollectionExtensions.cs
+++ b/backend/DramaLing.Api/Extensions/ServiceCollectionExtensions.cs
@@ -69,27 +69,35 @@ public static class ServiceCollectionExtensions
         services.AddSingleton<ICacheStrategyManager, CacheStrategyManager>();
         services.AddScoped<IDatabaseCacheManager, DatabaseCacheManager>();
 
-        // 快取提供者
-        services.AddScoped<ICacheProvider>(provider =>
-            new MemoryCacheProvider(
-                provider.GetRequiredService<Microsoft.Extensions.Caching.Memory.IMemoryCache>(),
-                provider.GetRequiredService<ILogger<MemoryCacheProvider>>()));
-
-        services.AddScoped<ICacheProvider>(provider =>
+        // 快取提供者 - 使用具名註冊
+        services.AddScoped<ICacheService>(provider =>
         {
+            var memoryCache = provider.GetRequiredService<Microsoft.Extensions.Caching.Memory.IMemoryCache>();
+            var logger = provider.GetRequiredService<ILogger<HybridCacheService>>();
+            var databaseCacheManager = provider.GetRequiredService<IDatabaseCacheManager>();
+            var strategyManager = provider.GetRequiredService<ICacheStrategyManager>();
+
+            var memoryProvider = new MemoryCacheProvider(
+                memoryCache,
+                provider.GetRequiredService<ILogger<MemoryCacheProvider>>());
+
+            ICacheProvider? distributedProvider = null;
             var distributedCache = provider.GetService<Microsoft.Extensions.Caching.Distributed.IDistributedCache>();
             if (distributedCache != null)
             {
-                return new DistributedCacheProvider(
+                distributedProvider = new DistributedCacheProvider(
                     distributedCache,
                     provider.GetRequiredService<ICacheSerializer>(),
                     provider.GetRequiredService<ILogger<DistributedCacheProvider>>());
             }
-            return null!;
-        });
 
-        // 主要快取服務
-        services.AddScoped<ICacheService, HybridCacheService>();
+            return new HybridCacheService(
+                memoryProvider,
+                distributedProvider,
+                databaseCacheManager,
+                strategyManager,
+                logger);
+        });
 
         return services;
     }
diff --git a/backend/DramaLing.Api/Migrations/20250930081940_FixFlashcardColumnNaming.Designer.cs b/backend/DramaLing.Api/Migrations/20250930081940_FixFlashcardColumnNaming.Designer.cs
new file mode 100644
index 0000000..02a0fad
--- /dev/null
+++ b/backend/DramaLing.Api/Migrations/20250930081940_FixFlashcardColumnNaming.Designer.cs
@@ -0,0 +1,1201 @@
+// <auto-generated />
+using System;
+using DramaLing.Api.Data;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace DramaLing.Api.Migrations
+{
+    [DbContext(typeof(DramaLingDbContext))]
+    [Migration("20250930081940_FixFlashcardColumnNaming")]
+    partial class FixFlashcardColumnNaming
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder.HasAnnotation("ProductVersion", "8.0.10");
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.AudioCache", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Accent")
+                        .IsRequired()
+                        .HasMaxLength(2)
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("AccessCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("access_count");
+
+                    b.Property<string>("AudioUrl")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("audio_url");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int?>("DurationMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("duration_ms");
+
+                    b.Property<int?>("FileSize")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("file_size");
+
+                    b.Property<DateTime>("LastAccessed")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("last_accessed");
+
+                    b.Property<string>("TextContent")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("text_content");
+
+                    b.Property<string>("TextHash")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("text_hash");
+
+                    b.Property<string>("VoiceId")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("voice_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("LastAccessed")
+                        .HasDatabaseName("IX_AudioCache_LastAccessed");
+
+                    b.HasIndex("TextHash")
+                        .IsUnique()
+                        .HasDatabaseName("IX_AudioCache_TextHash");
+
+                    b.ToTable("audio_cache", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.DailyStats", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("AiApiCalls")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("ai_api_calls");
+
+                    b.Property<int>("CardsGenerated")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("cards_generated");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<DateOnly>("Date")
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("SessionCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("session_count");
+
+                    b.Property<int>("StudyTimeSeconds")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("study_time_seconds");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.Property<int>("WordsCorrect")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("words_correct");
+
+                    b.Property<int>("WordsStudied")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("words_studied");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId", "Date")
+                        .IsUnique();
+
+                    b.ToTable("daily_stats", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ErrorReport", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("AdminNotes")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("admin_notes");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("Description")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<string>("ReportType")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("report_type");
+
+                    b.Property<DateTime?>("ResolvedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("resolved_at");
+
+                    b.Property<Guid?>("ResolvedBy")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("resolved_by");
+
+                    b.Property<string>("Status")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("StudyMode")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("study_mode");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("FlashcardId");
+
+                    b.HasIndex("ResolvedBy");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("error_reports", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ExampleImage", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("AccessCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("access_count");
+
+                    b.Property<string>("AltText")
+                        .HasMaxLength(200)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("alt_text");
+
+                    b.Property<string>("ContentHash")
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("content_hash");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int?>("FileSize")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("file_size");
+
+                    b.Property<decimal?>("GeminiCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_cost");
+
+                    b.Property<string>("GeminiDescription")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_description");
+
+                    b.Property<string>("GeminiPrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_prompt");
+
+                    b.Property<int?>("ImageHeight")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("image_height");
+
+                    b.Property<int?>("ImageWidth")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("image_width");
+
+                    b.Property<string>("ModerationNotes")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("moderation_notes");
+
+                    b.Property<string>("ModerationStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("moderation_status");
+
+                    b.Property<decimal?>("QualityScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("quality_score");
+
+                    b.Property<string>("RelativePath")
+                        .IsRequired()
+                        .HasMaxLength(500)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("relative_path");
+
+                    b.Property<decimal?>("ReplicateCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_cost");
+
+                    b.Property<string>("ReplicateModel")
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_model");
+
+                    b.Property<string>("ReplicatePrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_prompt");
+
+                    b.Property<string>("ReplicateVersion")
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_version");
+
+                    b.Property<decimal?>("TotalGenerationCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("total_generation_cost");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("AccessCount");
+
+                    b.HasIndex("ContentHash")
+                        .IsUnique();
+
+                    b.ToTable("example_images", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Flashcard", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("Definition")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("definition");
+
+                    b.Property<string>("DifficultyLevel")
+                        .HasMaxLength(10)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("difficulty_level");
+
+                    b.Property<string>("Example")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("example");
+
+                    b.Property<string>("ExampleTranslation")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("example_translation");
+
+                    b.Property<bool>("IsArchived")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_archived");
+
+                    b.Property<bool>("IsFavorite")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_favorite");
+
+                    b.Property<string>("PartOfSpeech")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("part_of_speech");
+
+                    b.Property<string>("Pronunciation")
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("pronunciation");
+
+                    b.Property<string>("Translation")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("translation");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.Property<string>("Word")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("word");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("flashcards", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardExampleImage", b =>
+                {
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<Guid>("ExampleImageId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("example_image_id");
+
+                    b.Property<decimal?>("ContextRelevance")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("context_relevance");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int>("DisplayOrder")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("display_order");
+
+                    b.Property<bool>("IsPrimary")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_primary");
+
+                    b.HasKey("FlashcardId", "ExampleImageId");
+
+                    b.HasIndex("ExampleImageId");
+
+                    b.ToTable("flashcard_example_images", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardTag", b =>
+                {
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<Guid>("TagId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("tag_id");
+
+                    b.HasKey("FlashcardId", "TagId");
+
+                    b.HasIndex("TagId");
+
+                    b.ToTable("flashcard_tags", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ImageGenerationRequest", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime?>("CompletedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("completed_at");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("FinalReplicatePrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("final_replicate_prompt");
+
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<DateTime?>("GeminiCompletedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_completed_at");
+
+                    b.Property<decimal?>("GeminiCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_cost");
+
+                    b.Property<string>("GeminiErrorMessage")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_error_message");
+
+                    b.Property<int?>("GeminiProcessingTimeMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("gemini_processing_time_ms");
+
+                    b.Property<string>("GeminiPrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_prompt");
+
+                    b.Property<DateTime?>("GeminiStartedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_started_at");
+
+                    b.Property<string>("GeminiStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_status");
+
+                    b.Property<string>("GeneratedDescription")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("generated_description");
+
+                    b.Property<Guid?>("GeneratedImageId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("generated_image_id");
+
+                    b.Property<string>("OriginalRequest")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("original_request");
+
+                    b.Property<string>("OverallStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("overall_status");
+
+                    b.Property<DateTime?>("ReplicateCompletedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_completed_at");
+
+                    b.Property<decimal?>("ReplicateCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_cost");
+
+                    b.Property<string>("ReplicateErrorMessage")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_error_message");
+
+                    b.Property<int?>("ReplicateProcessingTimeMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("replicate_processing_time_ms");
+
+                    b.Property<DateTime?>("ReplicateStartedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_started_at");
+
+                    b.Property<string>("ReplicateStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_status");
+
+                    b.Property<decimal?>("TotalCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("total_cost");
+
+                    b.Property<int?>("TotalProcessingTimeMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("total_processing_time_ms");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("FlashcardId");
+
+                    b.HasIndex("GeneratedImageId");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("image_generation_requests", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.OptionsVocabulary", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("CEFRLevel")
+                        .IsRequired()
+                        .HasMaxLength(2)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("cefr_level");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at")
+                        .HasDefaultValueSql("CURRENT_TIMESTAMP");
+
+                    b.Property<bool>("IsActive")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(true)
+                        .HasColumnName("is_active");
+
+                    b.Property<string>("PartOfSpeech")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("part_of_speech");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at")
+                        .HasDefaultValueSql("CURRENT_TIMESTAMP");
+
+                    b.Property<string>("Word")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("WordLength")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("word_length");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex(new[] { "IsActive" }, "IX_OptionsVocabulary_Active");
+
+                    b.HasIndex(new[] { "CEFRLevel" }, "IX_OptionsVocabulary_CEFR");
+
+                    b.HasIndex(new[] { "CEFRLevel", "PartOfSpeech", "WordLength" }, "IX_OptionsVocabulary_Core_Matching");
+
+                    b.HasIndex(new[] { "PartOfSpeech" }, "IX_OptionsVocabulary_PartOfSpeech");
+
+                    b.HasIndex(new[] { "Word" }, "IX_OptionsVocabulary_Word")
+                        .IsUnique();
+
+                    b.HasIndex(new[] { "WordLength" }, "IX_OptionsVocabulary_WordLength");
+
+                    b.ToTable("options_vocabularies", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.PronunciationAssessment", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal>("AccuracyScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("accuracy_score");
+
+                    b.Property<string>("AudioUrl")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("audio_url");
+
+                    b.Property<decimal>("CompletenessScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("completeness_score");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<Guid?>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<decimal>("FluencyScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("fluency_score");
+
+                    b.Property<int>("OverallScore")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("overall_score");
+
+                    b.Property<string>("PhonemeScores")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("phoneme_scores");
+
+                    b.Property<string>("PracticeMode")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("practice_mode");
+
+                    b.Property<decimal>("ProsodyScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("prosody_score");
+
+                    b.Property<string>("Suggestions")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("suggestions");
+
+                    b.Property<string>("TargetText")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("target_text");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("FlashcardId");
+
+                    b.HasIndex("UserId", "FlashcardId")
+                        .HasDatabaseName("IX_PronunciationAssessment_UserFlashcard");
+
+                    b.ToTable("pronunciation_assessments", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.SentenceAnalysisCache", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("AccessCount")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("AnalysisResult")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("CorrectedText")
+                        .HasMaxLength(1000)
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("ExpiresAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("GrammarCorrections")
+                        .HasColumnType("TEXT");
+
+                    b.Property<bool>("HasGrammarErrors")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("HighValueWords")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("IdiomsDetected")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("InputText")
+                        .IsRequired()
+                        .HasMaxLength(1000)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("InputTextHash")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime?>("LastAccessedAt")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("ExpiresAt")
+                        .HasDatabaseName("IX_SentenceAnalysisCache_Expires");
+
+                    b.HasIndex("InputTextHash")
+                        .HasDatabaseName("IX_SentenceAnalysisCache_Hash");
+
+                    b.HasIndex("InputTextHash", "ExpiresAt")
+                        .HasDatabaseName("IX_SentenceAnalysisCache_Hash_Expires");
+
+                    b.ToTable("SentenceAnalysisCache");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Color")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("UsageCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("usage_count");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("tags", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.User", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("AvatarUrl")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("avatar_url");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("DisplayName")
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("display_name");
+
+                    b.Property<string>("Email")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("email");
+
+                    b.Property<string>("EnglishLevel")
+                        .IsRequired()
+                        .HasMaxLength(10)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("english_level");
+
+                    b.Property<bool>("IsLevelVerified")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_level_verified");
+
+                    b.Property<string>("LevelNotes")
+                        .HasMaxLength(500)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("level_notes");
+
+                    b.Property<DateTime>("LevelUpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("level_updated_at");
+
+                    b.Property<string>("PasswordHash")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("password_hash");
+
+                    b.Property<string>("Preferences")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferences");
+
+                    b.Property<string>("SubscriptionType")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("subscription_type");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<string>("Username")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("username");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("Email")
+                        .IsUnique();
+
+                    b.HasIndex("Username")
+                        .IsUnique();
+
+                    b.ToTable("user_profiles", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserAudioPreferences", b =>
+                {
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<bool>("AutoPlayEnabled")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("auto_play_enabled");
+
+                    b.Property<decimal>("DefaultSpeed")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("default_speed");
+
+                    b.Property<bool>("EnableDetailedFeedback")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("enable_detailed_feedback");
+
+                    b.Property<string>("PreferredAccent")
+                        .IsRequired()
+                        .HasMaxLength(2)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferred_accent");
+
+                    b.Property<string>("PreferredVoiceFemale")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferred_voice_female");
+
+                    b.Property<string>("PreferredVoiceMale")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferred_voice_male");
+
+                    b.Property<string>("PronunciationDifficulty")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("pronunciation_difficulty");
+
+                    b.Property<int>("TargetScoreThreshold")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("target_score_threshold");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.HasKey("UserId");
+
+                    b.ToTable("user_audio_preferences", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserSettings", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<bool>("AutoPlayAudio")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("DailyGoal")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("DifficultyPreference")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT");
+
+                    b.Property<bool>("ReminderEnabled")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<TimeOnly>("ReminderTime")
+                        .HasColumnType("TEXT");
+
+                    b.Property<bool>("ShowPronunciation")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId")
+                        .IsUnique();
+
+                    b.ToTable("user_settings", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.WordQueryUsageStats", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateOnly>("Date")
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("HighValueWordClicks")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<int>("LowValueWordClicks")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<int>("SentenceAnalysisCount")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<int>("TotalApiCalls")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<int>("UniqueWordsQueried")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("CreatedAt")
+                        .HasDatabaseName("IX_WordQueryUsageStats_CreatedAt");
+
+                    b.HasIndex("UserId", "Date")
+                        .IsUnique()
+                        .HasDatabaseName("IX_WordQueryUsageStats_UserDate");
+
+                    b.ToTable("WordQueryUsageStats");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.DailyStats", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany("DailyStats")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ErrorReport", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany("ErrorReports")
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "ResolvedByUser")
+                        .WithMany()
+                        .HasForeignKey("ResolvedBy")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany("ErrorReports")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("ResolvedByUser");
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Flashcard", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany("Flashcards")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardExampleImage", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.ExampleImage", "ExampleImage")
+                        .WithMany("FlashcardExampleImages")
+                        .HasForeignKey("ExampleImageId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany("FlashcardExampleImages")
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("ExampleImage");
+
+                    b.Navigation("Flashcard");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardTag", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany("FlashcardTags")
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.Tag", "Tag")
+                        .WithMany("FlashcardTags")
+                        .HasForeignKey("TagId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("Tag");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ImageGenerationRequest", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany()
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.ExampleImage", "GeneratedImage")
+                        .WithMany()
+                        .HasForeignKey("GeneratedImageId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("GeneratedImage");
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.PronunciationAssessment", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany()
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserAudioPreferences", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithOne()
+                        .HasForeignKey("DramaLing.Api.Models.Entities.UserAudioPreferences", "UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserSettings", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithOne("Settings")
+                        .HasForeignKey("DramaLing.Api.Models.Entities.UserSettings", "UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.WordQueryUsageStats", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ExampleImage", b =>
+                {
+                    b.Navigation("FlashcardExampleImages");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Flashcard", b =>
+                {
+                    b.Navigation("ErrorReports");
+
+                    b.Navigation("FlashcardExampleImages");
+
+                    b.Navigation("FlashcardTags");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
+                {
+                    b.Navigation("FlashcardTags");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.User", b =>
+                {
+                    b.Navigation("DailyStats");
+
+                    b.Navigation("ErrorReports");
+
+                    b.Navigation("Flashcards");
+
+                    b.Navigation("Settings");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}
diff --git a/backend/DramaLing.Api/Migrations/20250930081940_FixFlashcardColumnNaming.cs b/backend/DramaLing.Api/Migrations/20250930081940_FixFlashcardColumnNaming.cs
new file mode 100644
index 0000000..5857e00
--- /dev/null
+++ b/backend/DramaLing.Api/Migrations/20250930081940_FixFlashcardColumnNaming.cs
@@ -0,0 +1,428 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace DramaLing.Api.Migrations
+{
+    /// <inheritdoc />
+    public partial class FixFlashcardColumnNaming : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "FK_pronunciation_assessments_study_sessions_study_session_id",
+                table: "pronunciation_assessments");
+
+            migrationBuilder.DropTable(
+                name: "study_records");
+
+            migrationBuilder.DropTable(
+                name: "test_results");
+
+            migrationBuilder.DropTable(
+                name: "study_cards");
+
+            migrationBuilder.DropTable(
+                name: "study_sessions");
+
+            migrationBuilder.DropIndex(
+                name: "IX_PronunciationAssessment_Session",
+                table: "pronunciation_assessments");
+
+            migrationBuilder.DropColumn(
+                name: "study_session_id",
+                table: "pronunciation_assessments");
+
+            migrationBuilder.DropColumn(
+                name: "FilledQuestionText",
+                table: "flashcards");
+
+            migrationBuilder.DropColumn(
+                name: "LastQuestionType",
+                table: "flashcards");
+
+            migrationBuilder.DropColumn(
+                name: "Repetitions",
+                table: "flashcards");
+
+            migrationBuilder.DropColumn(
+                name: "ReviewHistory",
+                table: "flashcards");
+
+            migrationBuilder.DropColumn(
+                name: "Synonyms",
+                table: "flashcards");
+
+            migrationBuilder.DropColumn(
+                name: "easiness_factor",
+                table: "flashcards");
+
+            migrationBuilder.DropColumn(
+                name: "interval_days",
+                table: "flashcards");
+
+            migrationBuilder.DropColumn(
+                name: "last_reviewed_at",
+                table: "flashcards");
+
+            migrationBuilder.DropColumn(
+                name: "mastery_level",
+                table: "flashcards");
+
+            migrationBuilder.DropColumn(
+                name: "next_review_date",
+                table: "flashcards");
+
+            migrationBuilder.DropColumn(
+                name: "times_correct",
+                table: "flashcards");
+
+            migrationBuilder.DropColumn(
+                name: "times_reviewed",
+                table: "flashcards");
+
+            migrationBuilder.RenameColumn(
+                name: "Word",
+                table: "flashcards",
+                newName: "word");
+
+            migrationBuilder.RenameColumn(
+                name: "Translation",
+                table: "flashcards",
+                newName: "translation");
+
+            migrationBuilder.RenameColumn(
+                name: "Pronunciation",
+                table: "flashcards",
+                newName: "pronunciation");
+
+            migrationBuilder.RenameColumn(
+                name: "Example",
+                table: "flashcards",
+                newName: "example");
+
+            migrationBuilder.RenameColumn(
+                name: "Definition",
+                table: "flashcards",
+                newName: "definition");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "definition",
+                table: "flashcards",
+                type: "TEXT",
+                nullable: true,
+                oldClrType: typeof(string),
+                oldType: "TEXT");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.RenameColumn(
+                name: "word",
+                table: "flashcards",
+                newName: "Word");
+
+            migrationBuilder.RenameColumn(
+                name: "translation",
+                table: "flashcards",
+                newName: "Translation");
+
+            migrationBuilder.RenameColumn(
+                name: "pronunciation",
+                table: "flashcards",
+                newName: "Pronunciation");
+
+            migrationBuilder.RenameColumn(
+                name: "example",
+                table: "flashcards",
+                newName: "Example");
+
+            migrationBuilder.RenameColumn(
+                name: "definition",
+                table: "flashcards",
+                newName: "Definition");
+
+            migrationBuilder.AddColumn<Guid>(
+                name: "study_session_id",
+                table: "pronunciation_assessments",
+                type: "TEXT",
+                nullable: true);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Definition",
+                table: "flashcards",
+                type: "TEXT",
+                nullable: false,
+                defaultValue: "",
+                oldClrType: typeof(string),
+                oldType: "TEXT",
+                oldNullable: true);
+
+            migrationBuilder.AddColumn<string>(
+                name: "FilledQuestionText",
+                table: "flashcards",
+                type: "TEXT",
+                maxLength: 1000,
+                nullable: true);
+
+            migrationBuilder.AddColumn<string>(
+                name: "LastQuestionType",
+                table: "flashcards",
+                type: "TEXT",
+                maxLength: 50,
+                nullable: true);
+
+            migrationBuilder.AddColumn<int>(
+                name: "Repetitions",
+                table: "flashcards",
+                type: "INTEGER",
+                nullable: false,
+                defaultValue: 0);
+
+            migrationBuilder.AddColumn<string>(
+                name: "ReviewHistory",
+                table: "flashcards",
+                type: "TEXT",
+                nullable: true);
+
+            migrationBuilder.AddColumn<string>(
+                name: "Synonyms",
+                table: "flashcards",
+                type: "TEXT",
+                maxLength: 2000,
+                nullable: true);
+
+            migrationBuilder.AddColumn<float>(
+                name: "easiness_factor",
+                table: "flashcards",
+                type: "REAL",
+                nullable: false,
+                defaultValue: 0f);
+
+            migrationBuilder.AddColumn<int>(
+                name: "interval_days",
+                table: "flashcards",
+                type: "INTEGER",
+                nullable: false,
+                defaultValue: 0);
+
+            migrationBuilder.AddColumn<DateTime>(
+                name: "last_reviewed_at",
+                table: "flashcards",
+                type: "TEXT",
+                nullable: true);
+
+            migrationBuilder.AddColumn<int>(
+                name: "mastery_level",
+                table: "flashcards",
+                type: "INTEGER",
+                nullable: false,
+                defaultValue: 0);
+
+            migrationBuilder.AddColumn<DateTime>(
+                name: "next_review_date",
+                table: "flashcards",
+                type: "TEXT",
+                nullable: false,
+                defaultValue: new DateTime(1, 1, 1, 0, 0, 0, 0, DateTimeKind.Unspecified));
+
+            migrationBuilder.AddColumn<int>(
+                name: "times_correct",
+                table: "flashcards",
+                type: "INTEGER",
+                nullable: false,
+                defaultValue: 0);
+
+            migrationBuilder.AddColumn<int>(
+                name: "times_reviewed",
+                table: "flashcards",
+                type: "INTEGER",
+                nullable: false,
+                defaultValue: 0);
+
+            migrationBuilder.CreateTable(
+                name: "study_sessions",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "TEXT", nullable: false),
+                    user_id = table.Column<Guid>(type: "TEXT", nullable: false),
+                    average_response_time_ms = table.Column<int>(type: "INTEGER", nullable: false),
+                    CompletedCards = table.Column<int>(type: "INTEGER", nullable: false),
+                    CompletedTests = table.Column<int>(type: "INTEGER", nullable: false),
+                    correct_count = table.Column<int>(type: "INTEGER", nullable: false),
+                    CurrentCardIndex = table.Column<int>(type: "INTEGER", nullable: false),
+                    CurrentTestType = table.Column<string>(type: "TEXT", maxLength: 50, nullable: true),
+                    duration_seconds = table.Column<int>(type: "INTEGER", nullable: false),
+                    ended_at = table.Column<DateTime>(type: "TEXT", nullable: true),
+                    session_type = table.Column<string>(type: "TEXT", maxLength: 50, nullable: false),
+                    started_at = table.Column<DateTime>(type: "TEXT", nullable: false),
+                    Status = table.Column<int>(type: "INTEGER", nullable: false),
+                    total_cards = table.Column<int>(type: "INTEGER", nullable: false),
+                    TotalTests = table.Column<int>(type: "INTEGER", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_study_sessions", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_study_sessions_user_profiles_user_id",
+                        column: x => x.user_id,
+                        principalTable: "user_profiles",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "study_cards",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "TEXT", nullable: false),
+                    FlashcardId = table.Column<Guid>(type: "TEXT", nullable: false),
+                    StudySessionId = table.Column<Guid>(type: "TEXT", nullable: false),
+                    CompletedAt = table.Column<DateTime>(type: "TEXT", nullable: true),
+                    IsCompleted = table.Column<bool>(type: "INTEGER", nullable: false),
+                    Order = table.Column<int>(type: "INTEGER", nullable: false),
+                    PlannedTests = table.Column<string>(type: "TEXT", nullable: false),
+                    PlannedTestsJson = table.Column<string>(type: "TEXT", nullable: false),
+                    StartedAt = table.Column<DateTime>(type: "TEXT", nullable: false),
+                    Word = table.Column<string>(type: "TEXT", maxLength: 100, nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_study_cards", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_study_cards_flashcards_FlashcardId",
+                        column: x => x.FlashcardId,
+                        principalTable: "flashcards",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                    table.ForeignKey(
+                        name: "FK_study_cards_study_sessions_StudySessionId",
+                        column: x => x.StudySessionId,
+                        principalTable: "study_sessions",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "study_records",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "TEXT", nullable: false),
+                    flashcard_id = table.Column<Guid>(type: "TEXT", nullable: false),
+                    session_id = table.Column<Guid>(type: "TEXT", nullable: false),
+                    user_id = table.Column<Guid>(type: "TEXT", nullable: false),
+                    is_correct = table.Column<bool>(type: "INTEGER", nullable: false),
+                    NewEasinessFactor = table.Column<float>(type: "REAL", nullable: false),
+                    NewIntervalDays = table.Column<int>(type: "INTEGER", nullable: false),
+                    NewRepetitions = table.Column<int>(type: "INTEGER", nullable: false),
+                    NextReviewDate = table.Column<DateTime>(type: "TEXT", nullable: false),
+                    PreviousEasinessFactor = table.Column<float>(type: "REAL", nullable: false),
+                    PreviousIntervalDays = table.Column<int>(type: "INTEGER", nullable: false),
+                    PreviousRepetitions = table.Column<int>(type: "INTEGER", nullable: false),
+                    quality_rating = table.Column<int>(type: "INTEGER", nullable: false),
+                    response_time_ms = table.Column<int>(type: "INTEGER", nullable: true),
+                    studied_at = table.Column<DateTime>(type: "TEXT", nullable: false),
+                    study_mode = table.Column<string>(type: "TEXT", maxLength: 50, nullable: false),
+                    user_answer = table.Column<string>(type: "TEXT", nullable: true)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_study_records", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_study_records_flashcards_flashcard_id",
+                        column: x => x.flashcard_id,
+                        principalTable: "flashcards",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                    table.ForeignKey(
+                        name: "FK_study_records_study_sessions_session_id",
+                        column: x => x.session_id,
+                        principalTable: "study_sessions",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                    table.ForeignKey(
+                        name: "FK_study_records_user_profiles_user_id",
+                        column: x => x.user_id,
+                        principalTable: "user_profiles",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "test_results",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "TEXT", nullable: false),
+                    StudyCardId = table.Column<Guid>(type: "TEXT", nullable: false),
+                    CompletedAt = table.Column<DateTime>(type: "TEXT", nullable: false),
+                    ConfidenceLevel = table.Column<int>(type: "INTEGER", nullable: true),
+                    IsCorrect = table.Column<bool>(type: "INTEGER", nullable: false),
+                    ResponseTimeMs = table.Column<int>(type: "INTEGER", nullable: false),
+                    TestType = table.Column<string>(type: "TEXT", maxLength: 50, nullable: false),
+                    UserAnswer = table.Column<string>(type: "TEXT", nullable: true)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_test_results", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_test_results_study_cards_StudyCardId",
+                        column: x => x.StudyCardId,
+                        principalTable: "study_cards",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_PronunciationAssessment_Session",
+                table: "pronunciation_assessments",
+                column: "study_session_id");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_study_cards_FlashcardId",
+                table: "study_cards",
+                column: "FlashcardId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_study_cards_StudySessionId",
+                table: "study_cards",
+                column: "StudySessionId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_study_records_flashcard_id",
+                table: "study_records",
+                column: "flashcard_id");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_study_records_session_id",
+                table: "study_records",
+                column: "session_id");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_StudyRecord_UserCard_TestType_Unique",
+                table: "study_records",
+                columns: new[] { "user_id", "flashcard_id", "study_mode" },
+                unique: true);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_study_sessions_user_id",
+                table: "study_sessions",
+                column: "user_id");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_test_results_StudyCardId",
+                table: "test_results",
+                column: "StudyCardId");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_pronunciation_assessments_study_sessions_study_session_id",
+                table: "pronunciation_assessments",
+                column: "study_session_id",
+                principalTable: "study_sessions",
+                principalColumn: "Id",
+                onDelete: ReferentialAction.SetNull);
+        }
+    }
+}
diff --git a/backend/DramaLing.Api/Migrations/20250930083856_CompleteSnakeCaseNaming.Designer.cs b/backend/DramaLing.Api/Migrations/20250930083856_CompleteSnakeCaseNaming.Designer.cs
new file mode 100644
index 0000000..70f6542
--- /dev/null
+++ b/backend/DramaLing.Api/Migrations/20250930083856_CompleteSnakeCaseNaming.Designer.cs
@@ -0,0 +1,1244 @@
+// <auto-generated />
+using System;
+using DramaLing.Api.Data;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace DramaLing.Api.Migrations
+{
+    [DbContext(typeof(DramaLingDbContext))]
+    [Migration("20250930083856_CompleteSnakeCaseNaming")]
+    partial class CompleteSnakeCaseNaming
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder.HasAnnotation("ProductVersion", "8.0.10");
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.AudioCache", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Accent")
+                        .IsRequired()
+                        .HasMaxLength(2)
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("AccessCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("access_count");
+
+                    b.Property<string>("AudioUrl")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("audio_url");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int?>("DurationMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("duration_ms");
+
+                    b.Property<int?>("FileSize")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("file_size");
+
+                    b.Property<DateTime>("LastAccessed")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("last_accessed");
+
+                    b.Property<string>("TextContent")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("text_content");
+
+                    b.Property<string>("TextHash")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("text_hash");
+
+                    b.Property<string>("VoiceId")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("voice_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("LastAccessed")
+                        .HasDatabaseName("IX_AudioCache_LastAccessed");
+
+                    b.HasIndex("TextHash")
+                        .IsUnique()
+                        .HasDatabaseName("IX_AudioCache_TextHash");
+
+                    b.ToTable("audio_cache", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.DailyStats", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<int>("AiApiCalls")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("ai_api_calls");
+
+                    b.Property<int>("CardsGenerated")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("cards_generated");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<DateOnly>("Date")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("date");
+
+                    b.Property<int>("SessionCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("session_count");
+
+                    b.Property<int>("StudyTimeSeconds")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("study_time_seconds");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.Property<int>("WordsCorrect")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("words_correct");
+
+                    b.Property<int>("WordsStudied")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("words_studied");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId", "Date")
+                        .IsUnique();
+
+                    b.ToTable("daily_stats", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ErrorReport", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("AdminNotes")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("admin_notes");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("Description")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("description");
+
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<string>("ReportType")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("report_type");
+
+                    b.Property<DateTime?>("ResolvedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("resolved_at");
+
+                    b.Property<Guid?>("ResolvedBy")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("resolved_by");
+
+                    b.Property<string>("Status")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("status");
+
+                    b.Property<string>("StudyMode")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("study_mode");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("FlashcardId");
+
+                    b.HasIndex("ResolvedBy");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("error_reports", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ExampleImage", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("AccessCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("access_count");
+
+                    b.Property<string>("AltText")
+                        .HasMaxLength(200)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("alt_text");
+
+                    b.Property<string>("ContentHash")
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("content_hash");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int?>("FileSize")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("file_size");
+
+                    b.Property<decimal?>("GeminiCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_cost");
+
+                    b.Property<string>("GeminiDescription")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_description");
+
+                    b.Property<string>("GeminiPrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_prompt");
+
+                    b.Property<int?>("ImageHeight")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("image_height");
+
+                    b.Property<int?>("ImageWidth")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("image_width");
+
+                    b.Property<string>("ModerationNotes")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("moderation_notes");
+
+                    b.Property<string>("ModerationStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("moderation_status");
+
+                    b.Property<decimal?>("QualityScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("quality_score");
+
+                    b.Property<string>("RelativePath")
+                        .IsRequired()
+                        .HasMaxLength(500)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("relative_path");
+
+                    b.Property<decimal?>("ReplicateCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_cost");
+
+                    b.Property<string>("ReplicateModel")
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_model");
+
+                    b.Property<string>("ReplicatePrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_prompt");
+
+                    b.Property<string>("ReplicateVersion")
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_version");
+
+                    b.Property<decimal?>("TotalGenerationCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("total_generation_cost");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("AccessCount");
+
+                    b.HasIndex("ContentHash")
+                        .IsUnique();
+
+                    b.ToTable("example_images", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Flashcard", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("Definition")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("definition");
+
+                    b.Property<string>("DifficultyLevel")
+                        .HasMaxLength(10)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("difficulty_level");
+
+                    b.Property<string>("Example")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("example");
+
+                    b.Property<string>("ExampleTranslation")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("example_translation");
+
+                    b.Property<bool>("IsArchived")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_archived");
+
+                    b.Property<bool>("IsFavorite")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_favorite");
+
+                    b.Property<string>("PartOfSpeech")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("part_of_speech");
+
+                    b.Property<string>("Pronunciation")
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("pronunciation");
+
+                    b.Property<string>("Translation")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("translation");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.Property<string>("Word")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("word");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("flashcards", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardExampleImage", b =>
+                {
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<Guid>("ExampleImageId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("example_image_id");
+
+                    b.Property<decimal?>("ContextRelevance")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("context_relevance");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int>("DisplayOrder")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("display_order");
+
+                    b.Property<bool>("IsPrimary")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_primary");
+
+                    b.HasKey("FlashcardId", "ExampleImageId");
+
+                    b.HasIndex("ExampleImageId");
+
+                    b.ToTable("flashcard_example_images", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardTag", b =>
+                {
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<Guid>("TagId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("tag_id");
+
+                    b.HasKey("FlashcardId", "TagId");
+
+                    b.HasIndex("TagId");
+
+                    b.ToTable("flashcard_tags", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ImageGenerationRequest", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime?>("CompletedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("completed_at");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("FinalReplicatePrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("final_replicate_prompt");
+
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<DateTime?>("GeminiCompletedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_completed_at");
+
+                    b.Property<decimal?>("GeminiCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_cost");
+
+                    b.Property<string>("GeminiErrorMessage")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_error_message");
+
+                    b.Property<int?>("GeminiProcessingTimeMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("gemini_processing_time_ms");
+
+                    b.Property<string>("GeminiPrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_prompt");
+
+                    b.Property<DateTime?>("GeminiStartedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_started_at");
+
+                    b.Property<string>("GeminiStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_status");
+
+                    b.Property<string>("GeneratedDescription")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("generated_description");
+
+                    b.Property<Guid?>("GeneratedImageId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("generated_image_id");
+
+                    b.Property<string>("OriginalRequest")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("original_request");
+
+                    b.Property<string>("OverallStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("overall_status");
+
+                    b.Property<DateTime?>("ReplicateCompletedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_completed_at");
+
+                    b.Property<decimal?>("ReplicateCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_cost");
+
+                    b.Property<string>("ReplicateErrorMessage")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_error_message");
+
+                    b.Property<int?>("ReplicateProcessingTimeMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("replicate_processing_time_ms");
+
+                    b.Property<DateTime?>("ReplicateStartedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_started_at");
+
+                    b.Property<string>("ReplicateStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_status");
+
+                    b.Property<decimal?>("TotalCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("total_cost");
+
+                    b.Property<int?>("TotalProcessingTimeMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("total_processing_time_ms");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("FlashcardId");
+
+                    b.HasIndex("GeneratedImageId");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("image_generation_requests", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.OptionsVocabulary", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("CEFRLevel")
+                        .IsRequired()
+                        .HasMaxLength(2)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("cefr_level");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at")
+                        .HasDefaultValueSql("CURRENT_TIMESTAMP");
+
+                    b.Property<bool>("IsActive")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(true)
+                        .HasColumnName("is_active");
+
+                    b.Property<string>("PartOfSpeech")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("part_of_speech");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at")
+                        .HasDefaultValueSql("CURRENT_TIMESTAMP");
+
+                    b.Property<string>("Word")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("WordLength")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("word_length");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex(new[] { "IsActive" }, "IX_OptionsVocabulary_Active");
+
+                    b.HasIndex(new[] { "CEFRLevel" }, "IX_OptionsVocabulary_CEFR");
+
+                    b.HasIndex(new[] { "CEFRLevel", "PartOfSpeech", "WordLength" }, "IX_OptionsVocabulary_Core_Matching");
+
+                    b.HasIndex(new[] { "PartOfSpeech" }, "IX_OptionsVocabulary_PartOfSpeech");
+
+                    b.HasIndex(new[] { "Word" }, "IX_OptionsVocabulary_Word")
+                        .IsUnique();
+
+                    b.HasIndex(new[] { "WordLength" }, "IX_OptionsVocabulary_WordLength");
+
+                    b.ToTable("options_vocabularies", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.PronunciationAssessment", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal>("AccuracyScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("accuracy_score");
+
+                    b.Property<string>("AudioUrl")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("audio_url");
+
+                    b.Property<decimal>("CompletenessScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("completeness_score");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<Guid?>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<decimal>("FluencyScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("fluency_score");
+
+                    b.Property<int>("OverallScore")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("overall_score");
+
+                    b.Property<string>("PhonemeScores")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("phoneme_scores");
+
+                    b.Property<string>("PracticeMode")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("practice_mode");
+
+                    b.Property<decimal>("ProsodyScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("prosody_score");
+
+                    b.Property<string>("Suggestions")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("suggestions");
+
+                    b.Property<string>("TargetText")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("target_text");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("FlashcardId");
+
+                    b.HasIndex("UserId", "FlashcardId")
+                        .HasDatabaseName("IX_PronunciationAssessment_UserFlashcard");
+
+                    b.ToTable("pronunciation_assessments", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.SentenceAnalysisCache", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<int>("AccessCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("access_count");
+
+                    b.Property<string>("AnalysisResult")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("analysis_result");
+
+                    b.Property<string>("CorrectedText")
+                        .HasMaxLength(1000)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("corrected_text");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<DateTime>("ExpiresAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("expires_at");
+
+                    b.Property<string>("GrammarCorrections")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("grammar_corrections");
+
+                    b.Property<bool>("HasGrammarErrors")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("has_grammar_errors");
+
+                    b.Property<string>("HighValueWords")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("high_value_words");
+
+                    b.Property<string>("IdiomsDetected")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("idioms_detected");
+
+                    b.Property<string>("InputText")
+                        .IsRequired()
+                        .HasMaxLength(1000)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("input_text");
+
+                    b.Property<string>("InputTextHash")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("input_text_hash");
+
+                    b.Property<DateTime?>("LastAccessedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("last_accessed_at");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("ExpiresAt")
+                        .HasDatabaseName("IX_SentenceAnalysisCache_Expires");
+
+                    b.HasIndex("InputTextHash")
+                        .HasDatabaseName("IX_SentenceAnalysisCache_Hash");
+
+                    b.HasIndex("InputTextHash", "ExpiresAt")
+                        .HasDatabaseName("IX_SentenceAnalysisCache_Hash_Expires");
+
+                    b.ToTable("SentenceAnalysisCache");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("Color")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("color");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("name");
+
+                    b.Property<int>("UsageCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("usage_count");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("tags", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.User", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("AvatarUrl")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("avatar_url");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("DisplayName")
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("display_name");
+
+                    b.Property<string>("Email")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("email");
+
+                    b.Property<string>("EnglishLevel")
+                        .IsRequired()
+                        .HasMaxLength(10)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("english_level");
+
+                    b.Property<bool>("IsLevelVerified")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_level_verified");
+
+                    b.Property<string>("LevelNotes")
+                        .HasMaxLength(500)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("level_notes");
+
+                    b.Property<DateTime>("LevelUpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("level_updated_at");
+
+                    b.Property<string>("PasswordHash")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("password_hash");
+
+                    b.Property<string>("Preferences")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferences");
+
+                    b.Property<string>("SubscriptionType")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("subscription_type");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<string>("Username")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("username");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("Email")
+                        .IsUnique();
+
+                    b.HasIndex("Username")
+                        .IsUnique();
+
+                    b.ToTable("user_profiles", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserAudioPreferences", b =>
+                {
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<bool>("AutoPlayEnabled")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("auto_play_enabled");
+
+                    b.Property<decimal>("DefaultSpeed")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("default_speed");
+
+                    b.Property<bool>("EnableDetailedFeedback")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("enable_detailed_feedback");
+
+                    b.Property<string>("PreferredAccent")
+                        .IsRequired()
+                        .HasMaxLength(2)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferred_accent");
+
+                    b.Property<string>("PreferredVoiceFemale")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferred_voice_female");
+
+                    b.Property<string>("PreferredVoiceMale")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferred_voice_male");
+
+                    b.Property<string>("PronunciationDifficulty")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("pronunciation_difficulty");
+
+                    b.Property<int>("TargetScoreThreshold")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("target_score_threshold");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.HasKey("UserId");
+
+                    b.ToTable("user_audio_preferences", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserSettings", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<bool>("AutoPlayAudio")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("auto_play_audio");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int>("DailyGoal")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("daily_goal");
+
+                    b.Property<string>("DifficultyPreference")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("difficulty_preference");
+
+                    b.Property<bool>("ReminderEnabled")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("reminder_enabled");
+
+                    b.Property<TimeOnly>("ReminderTime")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("reminder_time");
+
+                    b.Property<bool>("ShowPronunciation")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("show_pronunciation");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId")
+                        .IsUnique();
+
+                    b.ToTable("user_settings", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.WordQueryUsageStats", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<DateOnly>("Date")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("date");
+
+                    b.Property<int>("HighValueWordClicks")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("high_value_word_clicks");
+
+                    b.Property<int>("LowValueWordClicks")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("low_value_word_clicks");
+
+                    b.Property<int>("SentenceAnalysisCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("sentence_analysis_count");
+
+                    b.Property<int>("TotalApiCalls")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("total_api_calls");
+
+                    b.Property<int>("UniqueWordsQueried")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("unique_words_queried");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("CreatedAt")
+                        .HasDatabaseName("IX_WordQueryUsageStats_CreatedAt");
+
+                    b.HasIndex("UserId", "Date")
+                        .IsUnique()
+                        .HasDatabaseName("IX_WordQueryUsageStats_UserDate");
+
+                    b.ToTable("WordQueryUsageStats");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.DailyStats", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany("DailyStats")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ErrorReport", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany("ErrorReports")
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "ResolvedByUser")
+                        .WithMany()
+                        .HasForeignKey("ResolvedBy")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany("ErrorReports")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("ResolvedByUser");
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Flashcard", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany("Flashcards")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardExampleImage", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.ExampleImage", "ExampleImage")
+                        .WithMany("FlashcardExampleImages")
+                        .HasForeignKey("ExampleImageId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany("FlashcardExampleImages")
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("ExampleImage");
+
+                    b.Navigation("Flashcard");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardTag", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany("FlashcardTags")
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.Tag", "Tag")
+                        .WithMany("FlashcardTags")
+                        .HasForeignKey("TagId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("Tag");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ImageGenerationRequest", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany()
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.ExampleImage", "GeneratedImage")
+                        .WithMany()
+                        .HasForeignKey("GeneratedImageId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("GeneratedImage");
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.PronunciationAssessment", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany()
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserAudioPreferences", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithOne()
+                        .HasForeignKey("DramaLing.Api.Models.Entities.UserAudioPreferences", "UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserSettings", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithOne("Settings")
+                        .HasForeignKey("DramaLing.Api.Models.Entities.UserSettings", "UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.WordQueryUsageStats", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ExampleImage", b =>
+                {
+                    b.Navigation("FlashcardExampleImages");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Flashcard", b =>
+                {
+                    b.Navigation("ErrorReports");
+
+                    b.Navigation("FlashcardExampleImages");
+
+                    b.Navigation("FlashcardTags");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
+                {
+                    b.Navigation("FlashcardTags");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.User", b =>
+                {
+                    b.Navigation("DailyStats");
+
+                    b.Navigation("ErrorReports");
+
+                    b.Navigation("Flashcards");
+
+                    b.Navigation("Settings");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}
diff --git a/backend/DramaLing.Api/Migrations/20250930083856_CompleteSnakeCaseNaming.cs b/backend/DramaLing.Api/Migrations/20250930083856_CompleteSnakeCaseNaming.cs
new file mode 100644
index 0000000..fbf5f19
--- /dev/null
+++ b/backend/DramaLing.Api/Migrations/20250930083856_CompleteSnakeCaseNaming.cs
@@ -0,0 +1,516 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace DramaLing.Api.Migrations
+{
+    /// <inheritdoc />
+    public partial class CompleteSnakeCaseNaming : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "FK_user_settings_user_profiles_UserId",
+                table: "user_settings");
+
+            migrationBuilder.DropForeignKey(
+                name: "FK_WordQueryUsageStats_user_profiles_UserId",
+                table: "WordQueryUsageStats");
+
+            migrationBuilder.RenameColumn(
+                name: "Date",
+                table: "WordQueryUsageStats",
+                newName: "date");
+
+            migrationBuilder.RenameColumn(
+                name: "Id",
+                table: "WordQueryUsageStats",
+                newName: "id");
+
+            migrationBuilder.RenameColumn(
+                name: "UserId",
+                table: "WordQueryUsageStats",
+                newName: "user_id");
+
+            migrationBuilder.RenameColumn(
+                name: "UpdatedAt",
+                table: "WordQueryUsageStats",
+                newName: "updated_at");
+
+            migrationBuilder.RenameColumn(
+                name: "UniqueWordsQueried",
+                table: "WordQueryUsageStats",
+                newName: "unique_words_queried");
+
+            migrationBuilder.RenameColumn(
+                name: "TotalApiCalls",
+                table: "WordQueryUsageStats",
+                newName: "total_api_calls");
+
+            migrationBuilder.RenameColumn(
+                name: "SentenceAnalysisCount",
+                table: "WordQueryUsageStats",
+                newName: "sentence_analysis_count");
+
+            migrationBuilder.RenameColumn(
+                name: "LowValueWordClicks",
+                table: "WordQueryUsageStats",
+                newName: "low_value_word_clicks");
+
+            migrationBuilder.RenameColumn(
+                name: "HighValueWordClicks",
+                table: "WordQueryUsageStats",
+                newName: "high_value_word_clicks");
+
+            migrationBuilder.RenameColumn(
+                name: "CreatedAt",
+                table: "WordQueryUsageStats",
+                newName: "created_at");
+
+            migrationBuilder.RenameColumn(
+                name: "Id",
+                table: "user_settings",
+                newName: "id");
+
+            migrationBuilder.RenameColumn(
+                name: "UserId",
+                table: "user_settings",
+                newName: "user_id");
+
+            migrationBuilder.RenameColumn(
+                name: "UpdatedAt",
+                table: "user_settings",
+                newName: "updated_at");
+
+            migrationBuilder.RenameColumn(
+                name: "ShowPronunciation",
+                table: "user_settings",
+                newName: "show_pronunciation");
+
+            migrationBuilder.RenameColumn(
+                name: "ReminderTime",
+                table: "user_settings",
+                newName: "reminder_time");
+
+            migrationBuilder.RenameColumn(
+                name: "ReminderEnabled",
+                table: "user_settings",
+                newName: "reminder_enabled");
+
+            migrationBuilder.RenameColumn(
+                name: "DifficultyPreference",
+                table: "user_settings",
+                newName: "difficulty_preference");
+
+            migrationBuilder.RenameColumn(
+                name: "DailyGoal",
+                table: "user_settings",
+                newName: "daily_goal");
+
+            migrationBuilder.RenameColumn(
+                name: "CreatedAt",
+                table: "user_settings",
+                newName: "created_at");
+
+            migrationBuilder.RenameColumn(
+                name: "AutoPlayAudio",
+                table: "user_settings",
+                newName: "auto_play_audio");
+
+            migrationBuilder.RenameIndex(
+                name: "IX_user_settings_UserId",
+                table: "user_settings",
+                newName: "IX_user_settings_user_id");
+
+            migrationBuilder.RenameColumn(
+                name: "Id",
+                table: "user_profiles",
+                newName: "id");
+
+            migrationBuilder.RenameColumn(
+                name: "Name",
+                table: "tags",
+                newName: "name");
+
+            migrationBuilder.RenameColumn(
+                name: "Color",
+                table: "tags",
+                newName: "color");
+
+            migrationBuilder.RenameColumn(
+                name: "Id",
+                table: "tags",
+                newName: "id");
+
+            migrationBuilder.RenameColumn(
+                name: "Id",
+                table: "SentenceAnalysisCache",
+                newName: "id");
+
+            migrationBuilder.RenameColumn(
+                name: "LastAccessedAt",
+                table: "SentenceAnalysisCache",
+                newName: "last_accessed_at");
+
+            migrationBuilder.RenameColumn(
+                name: "InputTextHash",
+                table: "SentenceAnalysisCache",
+                newName: "input_text_hash");
+
+            migrationBuilder.RenameColumn(
+                name: "InputText",
+                table: "SentenceAnalysisCache",
+                newName: "input_text");
+
+            migrationBuilder.RenameColumn(
+                name: "IdiomsDetected",
+                table: "SentenceAnalysisCache",
+                newName: "idioms_detected");
+
+            migrationBuilder.RenameColumn(
+                name: "HighValueWords",
+                table: "SentenceAnalysisCache",
+                newName: "high_value_words");
+
+            migrationBuilder.RenameColumn(
+                name: "HasGrammarErrors",
+                table: "SentenceAnalysisCache",
+                newName: "has_grammar_errors");
+
+            migrationBuilder.RenameColumn(
+                name: "GrammarCorrections",
+                table: "SentenceAnalysisCache",
+                newName: "grammar_corrections");
+
+            migrationBuilder.RenameColumn(
+                name: "ExpiresAt",
+                table: "SentenceAnalysisCache",
+                newName: "expires_at");
+
+            migrationBuilder.RenameColumn(
+                name: "CreatedAt",
+                table: "SentenceAnalysisCache",
+                newName: "created_at");
+
+            migrationBuilder.RenameColumn(
+                name: "CorrectedText",
+                table: "SentenceAnalysisCache",
+                newName: "corrected_text");
+
+            migrationBuilder.RenameColumn(
+                name: "AnalysisResult",
+                table: "SentenceAnalysisCache",
+                newName: "analysis_result");
+
+            migrationBuilder.RenameColumn(
+                name: "AccessCount",
+                table: "SentenceAnalysisCache",
+                newName: "access_count");
+
+            migrationBuilder.RenameColumn(
+                name: "Id",
+                table: "flashcards",
+                newName: "id");
+
+            migrationBuilder.RenameColumn(
+                name: "Status",
+                table: "error_reports",
+                newName: "status");
+
+            migrationBuilder.RenameColumn(
+                name: "Description",
+                table: "error_reports",
+                newName: "description");
+
+            migrationBuilder.RenameColumn(
+                name: "Id",
+                table: "error_reports",
+                newName: "id");
+
+            migrationBuilder.RenameColumn(
+                name: "Date",
+                table: "daily_stats",
+                newName: "date");
+
+            migrationBuilder.RenameColumn(
+                name: "Id",
+                table: "daily_stats",
+                newName: "id");
+
+            migrationBuilder.RenameIndex(
+                name: "IX_daily_stats_user_id_Date",
+                table: "daily_stats",
+                newName: "IX_daily_stats_user_id_date");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_user_settings_user_profiles_user_id",
+                table: "user_settings",
+                column: "user_id",
+                principalTable: "user_profiles",
+                principalColumn: "id",
+                onDelete: ReferentialAction.Cascade);
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_WordQueryUsageStats_user_profiles_user_id",
+                table: "WordQueryUsageStats",
+                column: "user_id",
+                principalTable: "user_profiles",
+                principalColumn: "id",
+                onDelete: ReferentialAction.Cascade);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "FK_user_settings_user_profiles_user_id",
+                table: "user_settings");
+
+            migrationBuilder.DropForeignKey(
+                name: "FK_WordQueryUsageStats_user_profiles_user_id",
+                table: "WordQueryUsageStats");
+
+            migrationBuilder.RenameColumn(
+                name: "date",
+                table: "WordQueryUsageStats",
+                newName: "Date");
+
+            migrationBuilder.RenameColumn(
+                name: "id",
+                table: "WordQueryUsageStats",
+                newName: "Id");
+
+            migrationBuilder.RenameColumn(
+                name: "user_id",
+                table: "WordQueryUsageStats",
+                newName: "UserId");
+
+            migrationBuilder.RenameColumn(
+                name: "updated_at",
+                table: "WordQueryUsageStats",
+                newName: "UpdatedAt");
+
+            migrationBuilder.RenameColumn(
+                name: "unique_words_queried",
+                table: "WordQueryUsageStats",
+                newName: "UniqueWordsQueried");
+
+            migrationBuilder.RenameColumn(
+                name: "total_api_calls",
+                table: "WordQueryUsageStats",
+                newName: "TotalApiCalls");
+
+            migrationBuilder.RenameColumn(
+                name: "sentence_analysis_count",
+                table: "WordQueryUsageStats",
+                newName: "SentenceAnalysisCount");
+
+            migrationBuilder.RenameColumn(
+                name: "low_value_word_clicks",
+                table: "WordQueryUsageStats",
+                newName: "LowValueWordClicks");
+
+            migrationBuilder.RenameColumn(
+                name: "high_value_word_clicks",
+                table: "WordQueryUsageStats",
+                newName: "HighValueWordClicks");
+
+            migrationBuilder.RenameColumn(
+                name: "created_at",
+                table: "WordQueryUsageStats",
+                newName: "CreatedAt");
+
+            migrationBuilder.RenameColumn(
+                name: "id",
+                table: "user_settings",
+                newName: "Id");
+
+            migrationBuilder.RenameColumn(
+                name: "user_id",
+                table: "user_settings",
+                newName: "UserId");
+
+            migrationBuilder.RenameColumn(
+                name: "updated_at",
+                table: "user_settings",
+                newName: "UpdatedAt");
+
+            migrationBuilder.RenameColumn(
+                name: "show_pronunciation",
+                table: "user_settings",
+                newName: "ShowPronunciation");
+
+            migrationBuilder.RenameColumn(
+                name: "reminder_time",
+                table: "user_settings",
+                newName: "ReminderTime");
+
+            migrationBuilder.RenameColumn(
+                name: "reminder_enabled",
+                table: "user_settings",
+                newName: "ReminderEnabled");
+
+            migrationBuilder.RenameColumn(
+                name: "difficulty_preference",
+                table: "user_settings",
+                newName: "DifficultyPreference");
+
+            migrationBuilder.RenameColumn(
+                name: "daily_goal",
+                table: "user_settings",
+                newName: "DailyGoal");
+
+            migrationBuilder.RenameColumn(
+                name: "created_at",
+                table: "user_settings",
+                newName: "CreatedAt");
+
+            migrationBuilder.RenameColumn(
+                name: "auto_play_audio",
+                table: "user_settings",
+                newName: "AutoPlayAudio");
+
+            migrationBuilder.RenameIndex(
+                name: "IX_user_settings_user_id",
+                table: "user_settings",
+                newName: "IX_user_settings_UserId");
+
+            migrationBuilder.RenameColumn(
+                name: "id",
+                table: "user_profiles",
+                newName: "Id");
+
+            migrationBuilder.RenameColumn(
+                name: "name",
+                table: "tags",
+                newName: "Name");
+
+            migrationBuilder.RenameColumn(
+                name: "color",
+                table: "tags",
+                newName: "Color");
+
+            migrationBuilder.RenameColumn(
+                name: "id",
+                table: "tags",
+                newName: "Id");
+
+            migrationBuilder.RenameColumn(
+                name: "id",
+                table: "SentenceAnalysisCache",
+                newName: "Id");
+
+            migrationBuilder.RenameColumn(
+                name: "last_accessed_at",
+                table: "SentenceAnalysisCache",
+                newName: "LastAccessedAt");
+
+            migrationBuilder.RenameColumn(
+                name: "input_text_hash",
+                table: "SentenceAnalysisCache",
+                newName: "InputTextHash");
+
+            migrationBuilder.RenameColumn(
+                name: "input_text",
+                table: "SentenceAnalysisCache",
+                newName: "InputText");
+
+            migrationBuilder.RenameColumn(
+                name: "idioms_detected",
+                table: "SentenceAnalysisCache",
+                newName: "IdiomsDetected");
+
+            migrationBuilder.RenameColumn(
+                name: "high_value_words",
+                table: "SentenceAnalysisCache",
+                newName: "HighValueWords");
+
+            migrationBuilder.RenameColumn(
+                name: "has_grammar_errors",
+                table: "SentenceAnalysisCache",
+                newName: "HasGrammarErrors");
+
+            migrationBuilder.RenameColumn(
+                name: "grammar_corrections",
+                table: "SentenceAnalysisCache",
+                newName: "GrammarCorrections");
+
+            migrationBuilder.RenameColumn(
+                name: "expires_at",
+                table: "SentenceAnalysisCache",
+                newName: "ExpiresAt");
+
+            migrationBuilder.RenameColumn(
+                name: "created_at",
+                table: "SentenceAnalysisCache",
+                newName: "CreatedAt");
+
+            migrationBuilder.RenameColumn(
+                name: "corrected_text",
+                table: "SentenceAnalysisCache",
+                newName: "CorrectedText");
+
+            migrationBuilder.RenameColumn(
+                name: "analysis_result",
+                table: "SentenceAnalysisCache",
+                newName: "AnalysisResult");
+
+            migrationBuilder.RenameColumn(
+                name: "access_count",
+                table: "SentenceAnalysisCache",
+                newName: "AccessCount");
+
+            migrationBuilder.RenameColumn(
+                name: "id",
+                table: "flashcards",
+                newName: "Id");
+
+            migrationBuilder.RenameColumn(
+                name: "status",
+                table: "error_reports",
+                newName: "Status");
+
+            migrationBuilder.RenameColumn(
+                name: "description",
+                table: "error_reports",
+                newName: "Description");
+
+            migrationBuilder.RenameColumn(
+                name: "id",
+                table: "error_reports",
+                newName: "Id");
+
+            migrationBuilder.RenameColumn(
+                name: "date",
+                table: "daily_stats",
+                newName: "Date");
+
+            migrationBuilder.RenameColumn(
+                name: "id",
+                table: "daily_stats",
+                newName: "Id");
+
+            migrationBuilder.RenameIndex(
+                name: "IX_daily_stats_user_id_date",
+                table: "daily_stats",
+                newName: "IX_daily_stats_user_id_Date");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_user_settings_user_profiles_UserId",
+                table: "user_settings",
+                column: "UserId",
+                principalTable: "user_profiles",
+                principalColumn: "Id",
+                onDelete: ReferentialAction.Cascade);
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_WordQueryUsageStats_user_profiles_UserId",
+                table: "WordQueryUsageStats",
+                column: "UserId",
+                principalTable: "user_profiles",
+                principalColumn: "Id",
+                onDelete: ReferentialAction.Cascade);
+        }
+    }
+}
diff --git a/backend/DramaLing.Api/Migrations/20250930084945_FinalPascalCaseFieldsFix.Designer.cs b/backend/DramaLing.Api/Migrations/20250930084945_FinalPascalCaseFieldsFix.Designer.cs
new file mode 100644
index 0000000..9324ad6
--- /dev/null
+++ b/backend/DramaLing.Api/Migrations/20250930084945_FinalPascalCaseFieldsFix.Designer.cs
@@ -0,0 +1,1252 @@
+// <auto-generated />
+using System;
+using DramaLing.Api.Data;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace DramaLing.Api.Migrations
+{
+    [DbContext(typeof(DramaLingDbContext))]
+    [Migration("20250930084945_FinalPascalCaseFieldsFix")]
+    partial class FinalPascalCaseFieldsFix
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder.HasAnnotation("ProductVersion", "8.0.10");
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.AudioCache", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("Accent")
+                        .IsRequired()
+                        .HasMaxLength(2)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("accent");
+
+                    b.Property<int>("AccessCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("access_count");
+
+                    b.Property<string>("AudioUrl")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("audio_url");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int?>("DurationMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("duration_ms");
+
+                    b.Property<int?>("FileSize")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("file_size");
+
+                    b.Property<DateTime>("LastAccessed")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("last_accessed");
+
+                    b.Property<string>("TextContent")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("text_content");
+
+                    b.Property<string>("TextHash")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("text_hash");
+
+                    b.Property<string>("VoiceId")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("voice_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("LastAccessed")
+                        .HasDatabaseName("IX_AudioCache_LastAccessed");
+
+                    b.HasIndex("TextHash")
+                        .IsUnique()
+                        .HasDatabaseName("IX_AudioCache_TextHash");
+
+                    b.ToTable("audio_cache", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.DailyStats", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<int>("AiApiCalls")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("ai_api_calls");
+
+                    b.Property<int>("CardsGenerated")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("cards_generated");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<DateOnly>("Date")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("date");
+
+                    b.Property<int>("SessionCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("session_count");
+
+                    b.Property<int>("StudyTimeSeconds")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("study_time_seconds");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.Property<int>("WordsCorrect")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("words_correct");
+
+                    b.Property<int>("WordsStudied")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("words_studied");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId", "Date")
+                        .IsUnique();
+
+                    b.ToTable("daily_stats", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ErrorReport", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("AdminNotes")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("admin_notes");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("Description")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("description");
+
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<string>("ReportType")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("report_type");
+
+                    b.Property<DateTime?>("ResolvedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("resolved_at");
+
+                    b.Property<Guid?>("ResolvedBy")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("resolved_by");
+
+                    b.Property<string>("Status")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("status");
+
+                    b.Property<string>("StudyMode")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("study_mode");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("FlashcardId");
+
+                    b.HasIndex("ResolvedBy");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("error_reports", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ExampleImage", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<int>("AccessCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("access_count");
+
+                    b.Property<string>("AltText")
+                        .HasMaxLength(200)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("alt_text");
+
+                    b.Property<string>("ContentHash")
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("content_hash");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int?>("FileSize")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("file_size");
+
+                    b.Property<decimal?>("GeminiCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_cost");
+
+                    b.Property<string>("GeminiDescription")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_description");
+
+                    b.Property<string>("GeminiPrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_prompt");
+
+                    b.Property<int?>("ImageHeight")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("image_height");
+
+                    b.Property<int?>("ImageWidth")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("image_width");
+
+                    b.Property<string>("ModerationNotes")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("moderation_notes");
+
+                    b.Property<string>("ModerationStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("moderation_status");
+
+                    b.Property<decimal?>("QualityScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("quality_score");
+
+                    b.Property<string>("RelativePath")
+                        .IsRequired()
+                        .HasMaxLength(500)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("relative_path");
+
+                    b.Property<decimal?>("ReplicateCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_cost");
+
+                    b.Property<string>("ReplicateModel")
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_model");
+
+                    b.Property<string>("ReplicatePrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_prompt");
+
+                    b.Property<string>("ReplicateVersion")
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_version");
+
+                    b.Property<decimal?>("TotalGenerationCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("total_generation_cost");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("AccessCount");
+
+                    b.HasIndex("ContentHash")
+                        .IsUnique();
+
+                    b.ToTable("example_images", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Flashcard", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("Definition")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("definition");
+
+                    b.Property<string>("DifficultyLevel")
+                        .HasMaxLength(10)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("difficulty_level");
+
+                    b.Property<string>("Example")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("example");
+
+                    b.Property<string>("ExampleTranslation")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("example_translation");
+
+                    b.Property<bool>("IsArchived")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_archived");
+
+                    b.Property<bool>("IsFavorite")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_favorite");
+
+                    b.Property<string>("PartOfSpeech")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("part_of_speech");
+
+                    b.Property<string>("Pronunciation")
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("pronunciation");
+
+                    b.Property<string>("Translation")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("translation");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.Property<string>("Word")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("word");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("flashcards", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardExampleImage", b =>
+                {
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<Guid>("ExampleImageId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("example_image_id");
+
+                    b.Property<decimal?>("ContextRelevance")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("context_relevance");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int>("DisplayOrder")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("display_order");
+
+                    b.Property<bool>("IsPrimary")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_primary");
+
+                    b.HasKey("FlashcardId", "ExampleImageId");
+
+                    b.HasIndex("ExampleImageId");
+
+                    b.ToTable("flashcard_example_images", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardTag", b =>
+                {
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<Guid>("TagId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("tag_id");
+
+                    b.HasKey("FlashcardId", "TagId");
+
+                    b.HasIndex("TagId");
+
+                    b.ToTable("flashcard_tags", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ImageGenerationRequest", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<DateTime?>("CompletedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("completed_at");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("FinalReplicatePrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("final_replicate_prompt");
+
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<DateTime?>("GeminiCompletedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_completed_at");
+
+                    b.Property<decimal?>("GeminiCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_cost");
+
+                    b.Property<string>("GeminiErrorMessage")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_error_message");
+
+                    b.Property<int?>("GeminiProcessingTimeMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("gemini_processing_time_ms");
+
+                    b.Property<string>("GeminiPrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_prompt");
+
+                    b.Property<DateTime?>("GeminiStartedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_started_at");
+
+                    b.Property<string>("GeminiStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_status");
+
+                    b.Property<string>("GeneratedDescription")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("generated_description");
+
+                    b.Property<Guid?>("GeneratedImageId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("generated_image_id");
+
+                    b.Property<string>("OriginalRequest")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("original_request");
+
+                    b.Property<string>("OverallStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("overall_status");
+
+                    b.Property<DateTime?>("ReplicateCompletedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_completed_at");
+
+                    b.Property<decimal?>("ReplicateCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_cost");
+
+                    b.Property<string>("ReplicateErrorMessage")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_error_message");
+
+                    b.Property<int?>("ReplicateProcessingTimeMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("replicate_processing_time_ms");
+
+                    b.Property<DateTime?>("ReplicateStartedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_started_at");
+
+                    b.Property<string>("ReplicateStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_status");
+
+                    b.Property<decimal?>("TotalCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("total_cost");
+
+                    b.Property<int?>("TotalProcessingTimeMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("total_processing_time_ms");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("FlashcardId");
+
+                    b.HasIndex("GeneratedImageId");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("image_generation_requests", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.OptionsVocabulary", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("CEFRLevel")
+                        .IsRequired()
+                        .HasMaxLength(2)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("cefr_level");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at")
+                        .HasDefaultValueSql("CURRENT_TIMESTAMP");
+
+                    b.Property<bool>("IsActive")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(true)
+                        .HasColumnName("is_active");
+
+                    b.Property<string>("PartOfSpeech")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("part_of_speech");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at")
+                        .HasDefaultValueSql("CURRENT_TIMESTAMP");
+
+                    b.Property<string>("Word")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("word");
+
+                    b.Property<int>("WordLength")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("word_length");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex(new[] { "IsActive" }, "IX_OptionsVocabulary_Active");
+
+                    b.HasIndex(new[] { "CEFRLevel" }, "IX_OptionsVocabulary_CEFR");
+
+                    b.HasIndex(new[] { "CEFRLevel", "PartOfSpeech", "WordLength" }, "IX_OptionsVocabulary_Core_Matching");
+
+                    b.HasIndex(new[] { "PartOfSpeech" }, "IX_OptionsVocabulary_PartOfSpeech");
+
+                    b.HasIndex(new[] { "Word" }, "IX_OptionsVocabulary_Word")
+                        .IsUnique();
+
+                    b.HasIndex(new[] { "WordLength" }, "IX_OptionsVocabulary_WordLength");
+
+                    b.ToTable("options_vocabularies", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.PronunciationAssessment", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<decimal>("AccuracyScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("accuracy_score");
+
+                    b.Property<string>("AudioUrl")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("audio_url");
+
+                    b.Property<decimal>("CompletenessScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("completeness_score");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<Guid?>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<decimal>("FluencyScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("fluency_score");
+
+                    b.Property<int>("OverallScore")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("overall_score");
+
+                    b.Property<string>("PhonemeScores")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("phoneme_scores");
+
+                    b.Property<string>("PracticeMode")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("practice_mode");
+
+                    b.Property<decimal>("ProsodyScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("prosody_score");
+
+                    b.Property<string>("Suggestions")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("suggestions");
+
+                    b.Property<string>("TargetText")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("target_text");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("FlashcardId");
+
+                    b.HasIndex("UserId", "FlashcardId")
+                        .HasDatabaseName("IX_PronunciationAssessment_UserFlashcard");
+
+                    b.ToTable("pronunciation_assessments", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.SentenceAnalysisCache", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<int>("AccessCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("access_count");
+
+                    b.Property<string>("AnalysisResult")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("analysis_result");
+
+                    b.Property<string>("CorrectedText")
+                        .HasMaxLength(1000)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("corrected_text");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<DateTime>("ExpiresAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("expires_at");
+
+                    b.Property<string>("GrammarCorrections")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("grammar_corrections");
+
+                    b.Property<bool>("HasGrammarErrors")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("has_grammar_errors");
+
+                    b.Property<string>("HighValueWords")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("high_value_words");
+
+                    b.Property<string>("IdiomsDetected")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("idioms_detected");
+
+                    b.Property<string>("InputText")
+                        .IsRequired()
+                        .HasMaxLength(1000)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("input_text");
+
+                    b.Property<string>("InputTextHash")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("input_text_hash");
+
+                    b.Property<DateTime?>("LastAccessedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("last_accessed_at");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("ExpiresAt")
+                        .HasDatabaseName("IX_SentenceAnalysisCache_Expires");
+
+                    b.HasIndex("InputTextHash")
+                        .HasDatabaseName("IX_SentenceAnalysisCache_Hash");
+
+                    b.HasIndex("InputTextHash", "ExpiresAt")
+                        .HasDatabaseName("IX_SentenceAnalysisCache_Hash_Expires");
+
+                    b.ToTable("SentenceAnalysisCache");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("Color")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("color");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("name");
+
+                    b.Property<int>("UsageCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("usage_count");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("tags", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.User", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("AvatarUrl")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("avatar_url");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("DisplayName")
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("display_name");
+
+                    b.Property<string>("Email")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("email");
+
+                    b.Property<string>("EnglishLevel")
+                        .IsRequired()
+                        .HasMaxLength(10)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("english_level");
+
+                    b.Property<bool>("IsLevelVerified")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_level_verified");
+
+                    b.Property<string>("LevelNotes")
+                        .HasMaxLength(500)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("level_notes");
+
+                    b.Property<DateTime>("LevelUpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("level_updated_at");
+
+                    b.Property<string>("PasswordHash")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("password_hash");
+
+                    b.Property<string>("Preferences")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferences");
+
+                    b.Property<string>("SubscriptionType")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("subscription_type");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<string>("Username")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("username");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("Email")
+                        .IsUnique();
+
+                    b.HasIndex("Username")
+                        .IsUnique();
+
+                    b.ToTable("user_profiles", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserAudioPreferences", b =>
+                {
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.Property<bool>("AutoPlayEnabled")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("auto_play_enabled");
+
+                    b.Property<decimal>("DefaultSpeed")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("default_speed");
+
+                    b.Property<bool>("EnableDetailedFeedback")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("enable_detailed_feedback");
+
+                    b.Property<string>("PreferredAccent")
+                        .IsRequired()
+                        .HasMaxLength(2)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferred_accent");
+
+                    b.Property<string>("PreferredVoiceFemale")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferred_voice_female");
+
+                    b.Property<string>("PreferredVoiceMale")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferred_voice_male");
+
+                    b.Property<string>("PronunciationDifficulty")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("pronunciation_difficulty");
+
+                    b.Property<int>("TargetScoreThreshold")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("target_score_threshold");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.HasKey("UserId");
+
+                    b.ToTable("user_audio_preferences", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserSettings", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<bool>("AutoPlayAudio")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("auto_play_audio");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int>("DailyGoal")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("daily_goal");
+
+                    b.Property<string>("DifficultyPreference")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("difficulty_preference");
+
+                    b.Property<bool>("ReminderEnabled")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("reminder_enabled");
+
+                    b.Property<TimeOnly>("ReminderTime")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("reminder_time");
+
+                    b.Property<bool>("ShowPronunciation")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("show_pronunciation");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId")
+                        .IsUnique();
+
+                    b.ToTable("user_settings", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.WordQueryUsageStats", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<DateOnly>("Date")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("date");
+
+                    b.Property<int>("HighValueWordClicks")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("high_value_word_clicks");
+
+                    b.Property<int>("LowValueWordClicks")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("low_value_word_clicks");
+
+                    b.Property<int>("SentenceAnalysisCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("sentence_analysis_count");
+
+                    b.Property<int>("TotalApiCalls")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("total_api_calls");
+
+                    b.Property<int>("UniqueWordsQueried")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("unique_words_queried");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("CreatedAt")
+                        .HasDatabaseName("IX_WordQueryUsageStats_CreatedAt");
+
+                    b.HasIndex("UserId", "Date")
+                        .IsUnique()
+                        .HasDatabaseName("IX_WordQueryUsageStats_UserDate");
+
+                    b.ToTable("WordQueryUsageStats");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.DailyStats", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany("DailyStats")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ErrorReport", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany("ErrorReports")
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "ResolvedByUser")
+                        .WithMany()
+                        .HasForeignKey("ResolvedBy")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany("ErrorReports")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("ResolvedByUser");
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Flashcard", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany("Flashcards")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardExampleImage", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.ExampleImage", "ExampleImage")
+                        .WithMany("FlashcardExampleImages")
+                        .HasForeignKey("ExampleImageId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany("FlashcardExampleImages")
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("ExampleImage");
+
+                    b.Navigation("Flashcard");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardTag", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany("FlashcardTags")
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.Tag", "Tag")
+                        .WithMany("FlashcardTags")
+                        .HasForeignKey("TagId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("Tag");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ImageGenerationRequest", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany()
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.ExampleImage", "GeneratedImage")
+                        .WithMany()
+                        .HasForeignKey("GeneratedImageId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("GeneratedImage");
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.PronunciationAssessment", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany()
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserAudioPreferences", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithOne()
+                        .HasForeignKey("DramaLing.Api.Models.Entities.UserAudioPreferences", "UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserSettings", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithOne("Settings")
+                        .HasForeignKey("DramaLing.Api.Models.Entities.UserSettings", "UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.WordQueryUsageStats", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ExampleImage", b =>
+                {
+                    b.Navigation("FlashcardExampleImages");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Flashcard", b =>
+                {
+                    b.Navigation("ErrorReports");
+
+                    b.Navigation("FlashcardExampleImages");
+
+                    b.Navigation("FlashcardTags");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
+                {
+                    b.Navigation("FlashcardTags");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.User", b =>
+                {
+                    b.Navigation("DailyStats");
+
+                    b.Navigation("ErrorReports");
+
+                    b.Navigation("Flashcards");
+
+                    b.Navigation("Settings");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}
diff --git a/backend/DramaLing.Api/Migrations/20250930084945_FinalPascalCaseFieldsFix.cs b/backend/DramaLing.Api/Migrations/20250930084945_FinalPascalCaseFieldsFix.cs
new file mode 100644
index 0000000..aa05ccd
--- /dev/null
+++ b/backend/DramaLing.Api/Migrations/20250930084945_FinalPascalCaseFieldsFix.cs
@@ -0,0 +1,122 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace DramaLing.Api.Migrations
+{
+    /// <inheritdoc />
+    public partial class FinalPascalCaseFieldsFix : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "FK_user_audio_preferences_user_profiles_UserId",
+                table: "user_audio_preferences");
+
+            migrationBuilder.RenameColumn(
+                name: "UserId",
+                table: "user_audio_preferences",
+                newName: "user_id");
+
+            migrationBuilder.RenameColumn(
+                name: "Id",
+                table: "pronunciation_assessments",
+                newName: "id");
+
+            migrationBuilder.RenameColumn(
+                name: "Word",
+                table: "options_vocabularies",
+                newName: "word");
+
+            migrationBuilder.RenameColumn(
+                name: "Id",
+                table: "options_vocabularies",
+                newName: "id");
+
+            migrationBuilder.RenameColumn(
+                name: "Id",
+                table: "image_generation_requests",
+                newName: "id");
+
+            migrationBuilder.RenameColumn(
+                name: "Id",
+                table: "example_images",
+                newName: "id");
+
+            migrationBuilder.RenameColumn(
+                name: "Accent",
+                table: "audio_cache",
+                newName: "accent");
+
+            migrationBuilder.RenameColumn(
+                name: "Id",
+                table: "audio_cache",
+                newName: "id");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_user_audio_preferences_user_profiles_user_id",
+                table: "user_audio_preferences",
+                column: "user_id",
+                principalTable: "user_profiles",
+                principalColumn: "id",
+                onDelete: ReferentialAction.Cascade);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "FK_user_audio_preferences_user_profiles_user_id",
+                table: "user_audio_preferences");
+
+            migrationBuilder.RenameColumn(
+                name: "user_id",
+                table: "user_audio_preferences",
+                newName: "UserId");
+
+            migrationBuilder.RenameColumn(
+                name: "id",
+                table: "pronunciation_assessments",
+                newName: "Id");
+
+            migrationBuilder.RenameColumn(
+                name: "word",
+                table: "options_vocabularies",
+                newName: "Word");
+
+            migrationBuilder.RenameColumn(
+                name: "id",
+                table: "options_vocabularies",
+                newName: "Id");
+
+            migrationBuilder.RenameColumn(
+                name: "id",
+                table: "image_generation_requests",
+                newName: "Id");
+
+            migrationBuilder.RenameColumn(
+                name: "id",
+                table: "example_images",
+                newName: "Id");
+
+            migrationBuilder.RenameColumn(
+                name: "accent",
+                table: "audio_cache",
+                newName: "Accent");
+
+            migrationBuilder.RenameColumn(
+                name: "id",
+                table: "audio_cache",
+                newName: "Id");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_user_audio_preferences_user_profiles_UserId",
+                table: "user_audio_preferences",
+                column: "UserId",
+                principalTable: "user_profiles",
+                principalColumn: "id",
+                onDelete: ReferentialAction.Cascade);
+        }
+    }
+}
diff --git a/backend/DramaLing.Api/Migrations/20250930085131_FixTableNamesToSnakeCase.Designer.cs b/backend/DramaLing.Api/Migrations/20250930085131_FixTableNamesToSnakeCase.Designer.cs
new file mode 100644
index 0000000..3c4e84f
--- /dev/null
+++ b/backend/DramaLing.Api/Migrations/20250930085131_FixTableNamesToSnakeCase.Designer.cs
@@ -0,0 +1,1252 @@
+// <auto-generated />
+using System;
+using DramaLing.Api.Data;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace DramaLing.Api.Migrations
+{
+    [DbContext(typeof(DramaLingDbContext))]
+    [Migration("20250930085131_FixTableNamesToSnakeCase")]
+    partial class FixTableNamesToSnakeCase
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder.HasAnnotation("ProductVersion", "8.0.10");
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.AudioCache", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("Accent")
+                        .IsRequired()
+                        .HasMaxLength(2)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("accent");
+
+                    b.Property<int>("AccessCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("access_count");
+
+                    b.Property<string>("AudioUrl")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("audio_url");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int?>("DurationMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("duration_ms");
+
+                    b.Property<int?>("FileSize")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("file_size");
+
+                    b.Property<DateTime>("LastAccessed")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("last_accessed");
+
+                    b.Property<string>("TextContent")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("text_content");
+
+                    b.Property<string>("TextHash")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("text_hash");
+
+                    b.Property<string>("VoiceId")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("voice_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("LastAccessed")
+                        .HasDatabaseName("IX_AudioCache_LastAccessed");
+
+                    b.HasIndex("TextHash")
+                        .IsUnique()
+                        .HasDatabaseName("IX_AudioCache_TextHash");
+
+                    b.ToTable("audio_cache", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.DailyStats", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<int>("AiApiCalls")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("ai_api_calls");
+
+                    b.Property<int>("CardsGenerated")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("cards_generated");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<DateOnly>("Date")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("date");
+
+                    b.Property<int>("SessionCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("session_count");
+
+                    b.Property<int>("StudyTimeSeconds")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("study_time_seconds");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.Property<int>("WordsCorrect")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("words_correct");
+
+                    b.Property<int>("WordsStudied")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("words_studied");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId", "Date")
+                        .IsUnique();
+
+                    b.ToTable("daily_stats", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ErrorReport", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("AdminNotes")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("admin_notes");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("Description")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("description");
+
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<string>("ReportType")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("report_type");
+
+                    b.Property<DateTime?>("ResolvedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("resolved_at");
+
+                    b.Property<Guid?>("ResolvedBy")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("resolved_by");
+
+                    b.Property<string>("Status")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("status");
+
+                    b.Property<string>("StudyMode")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("study_mode");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("FlashcardId");
+
+                    b.HasIndex("ResolvedBy");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("error_reports", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ExampleImage", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<int>("AccessCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("access_count");
+
+                    b.Property<string>("AltText")
+                        .HasMaxLength(200)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("alt_text");
+
+                    b.Property<string>("ContentHash")
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("content_hash");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int?>("FileSize")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("file_size");
+
+                    b.Property<decimal?>("GeminiCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_cost");
+
+                    b.Property<string>("GeminiDescription")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_description");
+
+                    b.Property<string>("GeminiPrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_prompt");
+
+                    b.Property<int?>("ImageHeight")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("image_height");
+
+                    b.Property<int?>("ImageWidth")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("image_width");
+
+                    b.Property<string>("ModerationNotes")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("moderation_notes");
+
+                    b.Property<string>("ModerationStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("moderation_status");
+
+                    b.Property<decimal?>("QualityScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("quality_score");
+
+                    b.Property<string>("RelativePath")
+                        .IsRequired()
+                        .HasMaxLength(500)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("relative_path");
+
+                    b.Property<decimal?>("ReplicateCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_cost");
+
+                    b.Property<string>("ReplicateModel")
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_model");
+
+                    b.Property<string>("ReplicatePrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_prompt");
+
+                    b.Property<string>("ReplicateVersion")
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_version");
+
+                    b.Property<decimal?>("TotalGenerationCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("total_generation_cost");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("AccessCount");
+
+                    b.HasIndex("ContentHash")
+                        .IsUnique();
+
+                    b.ToTable("example_images", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Flashcard", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("Definition")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("definition");
+
+                    b.Property<string>("DifficultyLevel")
+                        .HasMaxLength(10)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("difficulty_level");
+
+                    b.Property<string>("Example")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("example");
+
+                    b.Property<string>("ExampleTranslation")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("example_translation");
+
+                    b.Property<bool>("IsArchived")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_archived");
+
+                    b.Property<bool>("IsFavorite")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_favorite");
+
+                    b.Property<string>("PartOfSpeech")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("part_of_speech");
+
+                    b.Property<string>("Pronunciation")
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("pronunciation");
+
+                    b.Property<string>("Translation")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("translation");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.Property<string>("Word")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("word");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("flashcards", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardExampleImage", b =>
+                {
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<Guid>("ExampleImageId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("example_image_id");
+
+                    b.Property<decimal?>("ContextRelevance")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("context_relevance");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int>("DisplayOrder")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("display_order");
+
+                    b.Property<bool>("IsPrimary")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_primary");
+
+                    b.HasKey("FlashcardId", "ExampleImageId");
+
+                    b.HasIndex("ExampleImageId");
+
+                    b.ToTable("flashcard_example_images", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardTag", b =>
+                {
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<Guid>("TagId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("tag_id");
+
+                    b.HasKey("FlashcardId", "TagId");
+
+                    b.HasIndex("TagId");
+
+                    b.ToTable("flashcard_tags", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ImageGenerationRequest", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<DateTime?>("CompletedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("completed_at");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("FinalReplicatePrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("final_replicate_prompt");
+
+                    b.Property<Guid>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<DateTime?>("GeminiCompletedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_completed_at");
+
+                    b.Property<decimal?>("GeminiCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_cost");
+
+                    b.Property<string>("GeminiErrorMessage")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_error_message");
+
+                    b.Property<int?>("GeminiProcessingTimeMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("gemini_processing_time_ms");
+
+                    b.Property<string>("GeminiPrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_prompt");
+
+                    b.Property<DateTime?>("GeminiStartedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_started_at");
+
+                    b.Property<string>("GeminiStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("gemini_status");
+
+                    b.Property<string>("GeneratedDescription")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("generated_description");
+
+                    b.Property<Guid?>("GeneratedImageId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("generated_image_id");
+
+                    b.Property<string>("OriginalRequest")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("original_request");
+
+                    b.Property<string>("OverallStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("overall_status");
+
+                    b.Property<DateTime?>("ReplicateCompletedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_completed_at");
+
+                    b.Property<decimal?>("ReplicateCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_cost");
+
+                    b.Property<string>("ReplicateErrorMessage")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_error_message");
+
+                    b.Property<int?>("ReplicateProcessingTimeMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("replicate_processing_time_ms");
+
+                    b.Property<DateTime?>("ReplicateStartedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_started_at");
+
+                    b.Property<string>("ReplicateStatus")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("replicate_status");
+
+                    b.Property<decimal?>("TotalCost")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("total_cost");
+
+                    b.Property<int?>("TotalProcessingTimeMs")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("total_processing_time_ms");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("FlashcardId");
+
+                    b.HasIndex("GeneratedImageId");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("image_generation_requests", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.OptionsVocabulary", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("CEFRLevel")
+                        .IsRequired()
+                        .HasMaxLength(2)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("cefr_level");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at")
+                        .HasDefaultValueSql("CURRENT_TIMESTAMP");
+
+                    b.Property<bool>("IsActive")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(true)
+                        .HasColumnName("is_active");
+
+                    b.Property<string>("PartOfSpeech")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("part_of_speech");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at")
+                        .HasDefaultValueSql("CURRENT_TIMESTAMP");
+
+                    b.Property<string>("Word")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("word");
+
+                    b.Property<int>("WordLength")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("word_length");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex(new[] { "IsActive" }, "IX_OptionsVocabulary_Active");
+
+                    b.HasIndex(new[] { "CEFRLevel" }, "IX_OptionsVocabulary_CEFR");
+
+                    b.HasIndex(new[] { "CEFRLevel", "PartOfSpeech", "WordLength" }, "IX_OptionsVocabulary_Core_Matching");
+
+                    b.HasIndex(new[] { "PartOfSpeech" }, "IX_OptionsVocabulary_PartOfSpeech");
+
+                    b.HasIndex(new[] { "Word" }, "IX_OptionsVocabulary_Word")
+                        .IsUnique();
+
+                    b.HasIndex(new[] { "WordLength" }, "IX_OptionsVocabulary_WordLength");
+
+                    b.ToTable("options_vocabularies", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.PronunciationAssessment", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<decimal>("AccuracyScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("accuracy_score");
+
+                    b.Property<string>("AudioUrl")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("audio_url");
+
+                    b.Property<decimal>("CompletenessScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("completeness_score");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<Guid?>("FlashcardId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("flashcard_id");
+
+                    b.Property<decimal>("FluencyScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("fluency_score");
+
+                    b.Property<int>("OverallScore")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("overall_score");
+
+                    b.Property<string>("PhonemeScores")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("phoneme_scores");
+
+                    b.Property<string>("PracticeMode")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("practice_mode");
+
+                    b.Property<decimal>("ProsodyScore")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("prosody_score");
+
+                    b.Property<string>("Suggestions")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("suggestions");
+
+                    b.Property<string>("TargetText")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("target_text");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("FlashcardId");
+
+                    b.HasIndex("UserId", "FlashcardId")
+                        .HasDatabaseName("IX_PronunciationAssessment_UserFlashcard");
+
+                    b.ToTable("pronunciation_assessments", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.SentenceAnalysisCache", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<int>("AccessCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("access_count");
+
+                    b.Property<string>("AnalysisResult")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("analysis_result");
+
+                    b.Property<string>("CorrectedText")
+                        .HasMaxLength(1000)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("corrected_text");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<DateTime>("ExpiresAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("expires_at");
+
+                    b.Property<string>("GrammarCorrections")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("grammar_corrections");
+
+                    b.Property<bool>("HasGrammarErrors")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("has_grammar_errors");
+
+                    b.Property<string>("HighValueWords")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("high_value_words");
+
+                    b.Property<string>("IdiomsDetected")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("idioms_detected");
+
+                    b.Property<string>("InputText")
+                        .IsRequired()
+                        .HasMaxLength(1000)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("input_text");
+
+                    b.Property<string>("InputTextHash")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("input_text_hash");
+
+                    b.Property<DateTime?>("LastAccessedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("last_accessed_at");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("ExpiresAt")
+                        .HasDatabaseName("IX_SentenceAnalysisCache_Expires");
+
+                    b.HasIndex("InputTextHash")
+                        .HasDatabaseName("IX_SentenceAnalysisCache_Hash");
+
+                    b.HasIndex("InputTextHash", "ExpiresAt")
+                        .HasDatabaseName("IX_SentenceAnalysisCache_Hash_Expires");
+
+                    b.ToTable("sentence_analysis_cache", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("Color")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("color");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("name");
+
+                    b.Property<int>("UsageCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("usage_count");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("tags", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.User", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("AvatarUrl")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("avatar_url");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("DisplayName")
+                        .HasMaxLength(100)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("display_name");
+
+                    b.Property<string>("Email")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("email");
+
+                    b.Property<string>("EnglishLevel")
+                        .IsRequired()
+                        .HasMaxLength(10)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("english_level");
+
+                    b.Property<bool>("IsLevelVerified")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("is_level_verified");
+
+                    b.Property<string>("LevelNotes")
+                        .HasMaxLength(500)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("level_notes");
+
+                    b.Property<DateTime>("LevelUpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("level_updated_at");
+
+                    b.Property<string>("PasswordHash")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("password_hash");
+
+                    b.Property<string>("Preferences")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferences");
+
+                    b.Property<string>("SubscriptionType")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("subscription_type");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<string>("Username")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("username");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("Email")
+                        .IsUnique();
+
+                    b.HasIndex("Username")
+                        .IsUnique();
+
+                    b.ToTable("user_profiles", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserAudioPreferences", b =>
+                {
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.Property<bool>("AutoPlayEnabled")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("auto_play_enabled");
+
+                    b.Property<decimal>("DefaultSpeed")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("default_speed");
+
+                    b.Property<bool>("EnableDetailedFeedback")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("enable_detailed_feedback");
+
+                    b.Property<string>("PreferredAccent")
+                        .IsRequired()
+                        .HasMaxLength(2)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferred_accent");
+
+                    b.Property<string>("PreferredVoiceFemale")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferred_voice_female");
+
+                    b.Property<string>("PreferredVoiceMale")
+                        .HasMaxLength(50)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("preferred_voice_male");
+
+                    b.Property<string>("PronunciationDifficulty")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("pronunciation_difficulty");
+
+                    b.Property<int>("TargetScoreThreshold")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("target_score_threshold");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.HasKey("UserId");
+
+                    b.ToTable("user_audio_preferences", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserSettings", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<bool>("AutoPlayAudio")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("auto_play_audio");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int>("DailyGoal")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("daily_goal");
+
+                    b.Property<string>("DifficultyPreference")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("TEXT")
+                        .HasColumnName("difficulty_preference");
+
+                    b.Property<bool>("ReminderEnabled")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("reminder_enabled");
+
+                    b.Property<TimeOnly>("ReminderTime")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("reminder_time");
+
+                    b.Property<bool>("ShowPronunciation")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("show_pronunciation");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId")
+                        .IsUnique();
+
+                    b.ToTable("user_settings", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.WordQueryUsageStats", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<DateOnly>("Date")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("date");
+
+                    b.Property<int>("HighValueWordClicks")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("high_value_word_clicks");
+
+                    b.Property<int>("LowValueWordClicks")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("low_value_word_clicks");
+
+                    b.Property<int>("SentenceAnalysisCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("sentence_analysis_count");
+
+                    b.Property<int>("TotalApiCalls")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("total_api_calls");
+
+                    b.Property<int>("UniqueWordsQueried")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("unique_words_queried");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("CreatedAt")
+                        .HasDatabaseName("IX_WordQueryUsageStats_CreatedAt");
+
+                    b.HasIndex("UserId", "Date")
+                        .IsUnique()
+                        .HasDatabaseName("IX_WordQueryUsageStats_UserDate");
+
+                    b.ToTable("word_query_usage_stats", (string)null);
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.DailyStats", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany("DailyStats")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ErrorReport", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany("ErrorReports")
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "ResolvedByUser")
+                        .WithMany()
+                        .HasForeignKey("ResolvedBy")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany("ErrorReports")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("ResolvedByUser");
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Flashcard", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany("Flashcards")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardExampleImage", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.ExampleImage", "ExampleImage")
+                        .WithMany("FlashcardExampleImages")
+                        .HasForeignKey("ExampleImageId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany("FlashcardExampleImages")
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("ExampleImage");
+
+                    b.Navigation("Flashcard");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.FlashcardTag", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany("FlashcardTags")
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.Tag", "Tag")
+                        .WithMany("FlashcardTags")
+                        .HasForeignKey("TagId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("Tag");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ImageGenerationRequest", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany()
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("DramaLing.Api.Models.Entities.ExampleImage", "GeneratedImage")
+                        .WithMany()
+                        .HasForeignKey("GeneratedImageId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("GeneratedImage");
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.PronunciationAssessment", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
+                        .WithMany()
+                        .HasForeignKey("FlashcardId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Flashcard");
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserAudioPreferences", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithOne()
+                        .HasForeignKey("DramaLing.Api.Models.Entities.UserAudioPreferences", "UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.UserSettings", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithOne("Settings")
+                        .HasForeignKey("DramaLing.Api.Models.Entities.UserSettings", "UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.WordQueryUsageStats", b =>
+                {
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.ExampleImage", b =>
+                {
+                    b.Navigation("FlashcardExampleImages");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Flashcard", b =>
+                {
+                    b.Navigation("ErrorReports");
+
+                    b.Navigation("FlashcardExampleImages");
+
+                    b.Navigation("FlashcardTags");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
+                {
+                    b.Navigation("FlashcardTags");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.User", b =>
+                {
+                    b.Navigation("DailyStats");
+
+                    b.Navigation("ErrorReports");
+
+                    b.Navigation("Flashcards");
+
+                    b.Navigation("Settings");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}
diff --git a/backend/DramaLing.Api/Migrations/20250930085131_FixTableNamesToSnakeCase.cs b/backend/DramaLing.Api/Migrations/20250930085131_FixTableNamesToSnakeCase.cs
new file mode 100644
index 0000000..d4f7cf4
--- /dev/null
+++ b/backend/DramaLing.Api/Migrations/20250930085131_FixTableNamesToSnakeCase.cs
@@ -0,0 +1,94 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace DramaLing.Api.Migrations
+{
+    /// <inheritdoc />
+    public partial class FixTableNamesToSnakeCase : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "FK_WordQueryUsageStats_user_profiles_user_id",
+                table: "WordQueryUsageStats");
+
+            migrationBuilder.DropPrimaryKey(
+                name: "PK_WordQueryUsageStats",
+                table: "WordQueryUsageStats");
+
+            migrationBuilder.DropPrimaryKey(
+                name: "PK_SentenceAnalysisCache",
+                table: "SentenceAnalysisCache");
+
+            migrationBuilder.RenameTable(
+                name: "WordQueryUsageStats",
+                newName: "word_query_usage_stats");
+
+            migrationBuilder.RenameTable(
+                name: "SentenceAnalysisCache",
+                newName: "sentence_analysis_cache");
+
+            migrationBuilder.AddPrimaryKey(
+                name: "PK_word_query_usage_stats",
+                table: "word_query_usage_stats",
+                column: "id");
+
+            migrationBuilder.AddPrimaryKey(
+                name: "PK_sentence_analysis_cache",
+                table: "sentence_analysis_cache",
+                column: "id");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_word_query_usage_stats_user_profiles_user_id",
+                table: "word_query_usage_stats",
+                column: "user_id",
+                principalTable: "user_profiles",
+                principalColumn: "id",
+                onDelete: ReferentialAction.Cascade);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "FK_word_query_usage_stats_user_profiles_user_id",
+                table: "word_query_usage_stats");
+
+            migrationBuilder.DropPrimaryKey(
+                name: "PK_word_query_usage_stats",
+                table: "word_query_usage_stats");
+
+            migrationBuilder.DropPrimaryKey(
+                name: "PK_sentence_analysis_cache",
+                table: "sentence_analysis_cache");
+
+            migrationBuilder.RenameTable(
+                name: "word_query_usage_stats",
+                newName: "WordQueryUsageStats");
+
+            migrationBuilder.RenameTable(
+                name: "sentence_analysis_cache",
+                newName: "SentenceAnalysisCache");
+
+            migrationBuilder.AddPrimaryKey(
+                name: "PK_WordQueryUsageStats",
+                table: "WordQueryUsageStats",
+                column: "id");
+
+            migrationBuilder.AddPrimaryKey(
+                name: "PK_SentenceAnalysisCache",
+                table: "SentenceAnalysisCache",
+                column: "id");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_WordQueryUsageStats_user_profiles_user_id",
+                table: "WordQueryUsageStats",
+                column: "user_id",
+                principalTable: "user_profiles",
+                principalColumn: "id",
+                onDelete: ReferentialAction.Cascade);
+        }
+    }
+}
diff --git a/backend/DramaLing.Api/Migrations/DramaLingDbContextModelSnapshot.cs b/backend/DramaLing.Api/Migrations/DramaLingDbContextModelSnapshot.cs
index fa59d9f..7382bec 100644
--- a/backend/DramaLing.Api/Migrations/DramaLingDbContextModelSnapshot.cs
+++ b/backend/DramaLing.Api/Migrations/DramaLingDbContextModelSnapshot.cs
@@ -21,12 +21,14 @@ namespace DramaLing.Api.Migrations
                 {
                     b.Property<Guid>("Id")
                         .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
 
                     b.Property<string>("Accent")
                         .IsRequired()
                         .HasMaxLength(2)
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("accent");
 
                     b.Property<int>("AccessCount")
                         .HasColumnType("INTEGER")
@@ -86,7 +88,8 @@ namespace DramaLing.Api.Migrations
                 {
                     b.Property<Guid>("Id")
                         .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
 
                     b.Property<int>("AiApiCalls")
                         .HasColumnType("INTEGER")
@@ -101,7 +104,8 @@ namespace DramaLing.Api.Migrations
                         .HasColumnName("created_at");
 
                     b.Property<DateOnly>("Date")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("date");
 
                     b.Property<int>("SessionCount")
                         .HasColumnType("INTEGER")
@@ -135,7 +139,8 @@ namespace DramaLing.Api.Migrations
                 {
                     b.Property<Guid>("Id")
                         .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
 
                     b.Property<string>("AdminNotes")
                         .HasColumnType("TEXT")
@@ -146,7 +151,8 @@ namespace DramaLing.Api.Migrations
                         .HasColumnName("created_at");
 
                     b.Property<string>("Description")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("description");
 
                     b.Property<Guid>("FlashcardId")
                         .HasColumnType("TEXT")
@@ -169,7 +175,8 @@ namespace DramaLing.Api.Migrations
                     b.Property<string>("Status")
                         .IsRequired()
                         .HasMaxLength(50)
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("status");
 
                     b.Property<string>("StudyMode")
                         .HasMaxLength(50)
@@ -195,7 +202,8 @@ namespace DramaLing.Api.Migrations
                 {
                     b.Property<Guid>("Id")
                         .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
 
                     b.Property<int>("AccessCount")
                         .HasColumnType("INTEGER")
@@ -299,40 +307,30 @@ namespace DramaLing.Api.Migrations
                 {
                     b.Property<Guid>("Id")
                         .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
 
                     b.Property<DateTime>("CreatedAt")
                         .HasColumnType("TEXT")
                         .HasColumnName("created_at");
 
                     b.Property<string>("Definition")
-                        .IsRequired()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("definition");
 
                     b.Property<string>("DifficultyLevel")
                         .HasMaxLength(10)
                         .HasColumnType("TEXT")
                         .HasColumnName("difficulty_level");
 
-                    b.Property<float>("EasinessFactor")
-                        .HasColumnType("REAL")
-                        .HasColumnName("easiness_factor");
-
                     b.Property<string>("Example")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("example");
 
                     b.Property<string>("ExampleTranslation")
                         .HasColumnType("TEXT")
                         .HasColumnName("example_translation");
 
-                    b.Property<string>("FilledQuestionText")
-                        .HasMaxLength(1000)
-                        .HasColumnType("TEXT");
-
-                    b.Property<int>("IntervalDays")
-                        .HasColumnType("INTEGER")
-                        .HasColumnName("interval_days");
-
                     b.Property<bool>("IsArchived")
                         .HasColumnType("INTEGER")
                         .HasColumnName("is_archived");
@@ -341,22 +339,6 @@ namespace DramaLing.Api.Migrations
                         .HasColumnType("INTEGER")
                         .HasColumnName("is_favorite");
 
-                    b.Property<string>("LastQuestionType")
-                        .HasMaxLength(50)
-                        .HasColumnType("TEXT");
-
-                    b.Property<DateTime?>("LastReviewedAt")
-                        .HasColumnType("TEXT")
-                        .HasColumnName("last_reviewed_at");
-
-                    b.Property<int>("MasteryLevel")
-                        .HasColumnType("INTEGER")
-                        .HasColumnName("mastery_level");
-
-                    b.Property<DateTime>("NextReviewDate")
-                        .HasColumnType("TEXT")
-                        .HasColumnName("next_review_date");
-
                     b.Property<string>("PartOfSpeech")
                         .HasMaxLength(50)
                         .HasColumnType("TEXT")
@@ -364,29 +346,13 @@ namespace DramaLing.Api.Migrations
 
                     b.Property<string>("Pronunciation")
                         .HasMaxLength(255)
-                        .HasColumnType("TEXT");
-
-                    b.Property<int>("Repetitions")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<string>("ReviewHistory")
-                        .HasColumnType("TEXT");
-
-                    b.Property<string>("Synonyms")
-                        .HasMaxLength(2000)
-                        .HasColumnType("TEXT");
-
-                    b.Property<int>("TimesCorrect")
-                        .HasColumnType("INTEGER")
-                        .HasColumnName("times_correct");
-
-                    b.Property<int>("TimesReviewed")
-                        .HasColumnType("INTEGER")
-                        .HasColumnName("times_reviewed");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("pronunciation");
 
                     b.Property<string>("Translation")
                         .IsRequired()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("translation");
 
                     b.Property<DateTime>("UpdatedAt")
                         .HasColumnType("TEXT")
@@ -399,7 +365,8 @@ namespace DramaLing.Api.Migrations
                     b.Property<string>("Word")
                         .IsRequired()
                         .HasMaxLength(255)
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("word");
 
                     b.HasKey("Id");
 
@@ -462,7 +429,8 @@ namespace DramaLing.Api.Migrations
                 {
                     b.Property<Guid>("Id")
                         .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
 
                     b.Property<DateTime?>("CompletedAt")
                         .HasColumnType("TEXT")
@@ -582,7 +550,8 @@ namespace DramaLing.Api.Migrations
                 {
                     b.Property<Guid>("Id")
                         .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
 
                     b.Property<string>("CEFRLevel")
                         .IsRequired()
@@ -617,7 +586,8 @@ namespace DramaLing.Api.Migrations
                     b.Property<string>("Word")
                         .IsRequired()
                         .HasMaxLength(100)
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("word");
 
                     b.Property<int>("WordLength")
                         .HasColumnType("INTEGER")
@@ -645,7 +615,8 @@ namespace DramaLing.Api.Migrations
                 {
                     b.Property<Guid>("Id")
                         .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
 
                     b.Property<decimal>("AccuracyScore")
                         .HasColumnType("TEXT")
@@ -689,10 +660,6 @@ namespace DramaLing.Api.Migrations
                         .HasColumnType("TEXT")
                         .HasColumnName("prosody_score");
 
-                    b.Property<Guid?>("StudySessionId")
-                        .HasColumnType("TEXT")
-                        .HasColumnName("study_session_id");
-
                     b.Property<string>("Suggestions")
                         .HasColumnType("TEXT")
                         .HasColumnName("suggestions");
@@ -710,9 +677,6 @@ namespace DramaLing.Api.Migrations
 
                     b.HasIndex("FlashcardId");
 
-                    b.HasIndex("StudySessionId")
-                        .HasDatabaseName("IX_PronunciationAssessment_Session");
-
                     b.HasIndex("UserId", "FlashcardId")
                         .HasDatabaseName("IX_PronunciationAssessment_UserFlashcard");
 
@@ -723,49 +687,62 @@ namespace DramaLing.Api.Migrations
                 {
                     b.Property<Guid>("Id")
                         .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
 
                     b.Property<int>("AccessCount")
-                        .HasColumnType("INTEGER");
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("access_count");
 
                     b.Property<string>("AnalysisResult")
                         .IsRequired()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("analysis_result");
 
                     b.Property<string>("CorrectedText")
                         .HasMaxLength(1000)
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("corrected_text");
 
                     b.Property<DateTime>("CreatedAt")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
 
                     b.Property<DateTime>("ExpiresAt")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("expires_at");
 
                     b.Property<string>("GrammarCorrections")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("grammar_corrections");
 
                     b.Property<bool>("HasGrammarErrors")
-                        .HasColumnType("INTEGER");
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("has_grammar_errors");
 
                     b.Property<string>("HighValueWords")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("high_value_words");
 
                     b.Property<string>("IdiomsDetected")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("idioms_detected");
 
                     b.Property<string>("InputText")
                         .IsRequired()
                         .HasMaxLength(1000)
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("input_text");
 
                     b.Property<string>("InputTextHash")
                         .IsRequired()
                         .HasMaxLength(64)
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("input_text_hash");
 
                     b.Property<DateTime?>("LastAccessedAt")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("last_accessed_at");
 
                     b.HasKey("Id");
 
@@ -778,209 +755,21 @@ namespace DramaLing.Api.Migrations
                     b.HasIndex("InputTextHash", "ExpiresAt")
                         .HasDatabaseName("IX_SentenceAnalysisCache_Hash_Expires");
 
-                    b.ToTable("SentenceAnalysisCache");
-                });
-
-            modelBuilder.Entity("DramaLing.Api.Models.Entities.StudyCard", b =>
-                {
-                    b.Property<Guid>("Id")
-                        .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
-
-                    b.Property<DateTime?>("CompletedAt")
-                        .HasColumnType("TEXT");
-
-                    b.Property<Guid>("FlashcardId")
-                        .HasColumnType("TEXT");
-
-                    b.Property<bool>("IsCompleted")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<int>("Order")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<string>("PlannedTests")
-                        .IsRequired()
-                        .HasColumnType("TEXT");
-
-                    b.Property<string>("PlannedTestsJson")
-                        .IsRequired()
-                        .HasColumnType("TEXT");
-
-                    b.Property<DateTime>("StartedAt")
-                        .HasColumnType("TEXT");
-
-                    b.Property<Guid>("StudySessionId")
-                        .HasColumnType("TEXT");
-
-                    b.Property<string>("Word")
-                        .IsRequired()
-                        .HasMaxLength(100)
-                        .HasColumnType("TEXT");
-
-                    b.HasKey("Id");
-
-                    b.HasIndex("FlashcardId");
-
-                    b.HasIndex("StudySessionId");
-
-                    b.ToTable("study_cards", (string)null);
-                });
-
-            modelBuilder.Entity("DramaLing.Api.Models.Entities.StudyRecord", b =>
-                {
-                    b.Property<Guid>("Id")
-                        .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
-
-                    b.Property<Guid>("FlashcardId")
-                        .HasColumnType("TEXT")
-                        .HasColumnName("flashcard_id");
-
-                    b.Property<bool>("IsCorrect")
-                        .HasColumnType("INTEGER")
-                        .HasColumnName("is_correct");
-
-                    b.Property<float>("NewEasinessFactor")
-                        .HasColumnType("REAL");
-
-                    b.Property<int>("NewIntervalDays")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<int>("NewRepetitions")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<DateTime>("NextReviewDate")
-                        .HasColumnType("TEXT");
-
-                    b.Property<float>("PreviousEasinessFactor")
-                        .HasColumnType("REAL");
-
-                    b.Property<int>("PreviousIntervalDays")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<int>("PreviousRepetitions")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<int>("QualityRating")
-                        .HasColumnType("INTEGER")
-                        .HasColumnName("quality_rating");
-
-                    b.Property<int?>("ResponseTimeMs")
-                        .HasColumnType("INTEGER")
-                        .HasColumnName("response_time_ms");
-
-                    b.Property<Guid>("SessionId")
-                        .HasColumnType("TEXT")
-                        .HasColumnName("session_id");
-
-                    b.Property<DateTime>("StudiedAt")
-                        .HasColumnType("TEXT")
-                        .HasColumnName("studied_at");
-
-                    b.Property<string>("StudyMode")
-                        .IsRequired()
-                        .HasMaxLength(50)
-                        .HasColumnType("TEXT")
-                        .HasColumnName("study_mode");
-
-                    b.Property<string>("UserAnswer")
-                        .HasColumnType("TEXT")
-                        .HasColumnName("user_answer");
-
-                    b.Property<Guid>("UserId")
-                        .HasColumnType("TEXT")
-                        .HasColumnName("user_id");
-
-                    b.HasKey("Id");
-
-                    b.HasIndex("FlashcardId");
-
-                    b.HasIndex("SessionId");
-
-                    b.HasIndex("UserId", "FlashcardId", "StudyMode")
-                        .IsUnique()
-                        .HasDatabaseName("IX_StudyRecord_UserCard_TestType_Unique");
-
-                    b.ToTable("study_records", (string)null);
-                });
-
-            modelBuilder.Entity("DramaLing.Api.Models.Entities.StudySession", b =>
-                {
-                    b.Property<Guid>("Id")
-                        .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
-
-                    b.Property<int>("AverageResponseTimeMs")
-                        .HasColumnType("INTEGER")
-                        .HasColumnName("average_response_time_ms");
-
-                    b.Property<int>("CompletedCards")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<int>("CompletedTests")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<int>("CorrectCount")
-                        .HasColumnType("INTEGER")
-                        .HasColumnName("correct_count");
-
-                    b.Property<int>("CurrentCardIndex")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<string>("CurrentTestType")
-                        .HasMaxLength(50)
-                        .HasColumnType("TEXT");
-
-                    b.Property<int>("DurationSeconds")
-                        .HasColumnType("INTEGER")
-                        .HasColumnName("duration_seconds");
-
-                    b.Property<DateTime?>("EndedAt")
-                        .HasColumnType("TEXT")
-                        .HasColumnName("ended_at");
-
-                    b.Property<string>("SessionType")
-                        .IsRequired()
-                        .HasMaxLength(50)
-                        .HasColumnType("TEXT")
-                        .HasColumnName("session_type");
-
-                    b.Property<DateTime>("StartedAt")
-                        .HasColumnType("TEXT")
-                        .HasColumnName("started_at");
-
-                    b.Property<int>("Status")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<int>("TotalCards")
-                        .HasColumnType("INTEGER")
-                        .HasColumnName("total_cards");
-
-                    b.Property<int>("TotalTests")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<Guid>("UserId")
-                        .HasColumnType("TEXT")
-                        .HasColumnName("user_id");
-
-                    b.HasKey("Id");
-
-                    b.HasIndex("UserId");
-
-                    b.ToTable("study_sessions", (string)null);
+                    b.ToTable("sentence_analysis_cache", (string)null);
                 });
 
             modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
                 {
                     b.Property<Guid>("Id")
                         .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
 
                     b.Property<string>("Color")
                         .IsRequired()
                         .HasMaxLength(50)
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("color");
 
                     b.Property<DateTime>("CreatedAt")
                         .HasColumnType("TEXT")
@@ -989,7 +778,8 @@ namespace DramaLing.Api.Migrations
                     b.Property<string>("Name")
                         .IsRequired()
                         .HasMaxLength(100)
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("name");
 
                     b.Property<int>("UsageCount")
                         .HasColumnType("INTEGER")
@@ -1006,47 +796,12 @@ namespace DramaLing.Api.Migrations
                     b.ToTable("tags", (string)null);
                 });
 
-            modelBuilder.Entity("DramaLing.Api.Models.Entities.TestResult", b =>
-                {
-                    b.Property<Guid>("Id")
-                        .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
-
-                    b.Property<DateTime>("CompletedAt")
-                        .HasColumnType("TEXT");
-
-                    b.Property<int?>("ConfidenceLevel")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<bool>("IsCorrect")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<int>("ResponseTimeMs")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<Guid>("StudyCardId")
-                        .HasColumnType("TEXT");
-
-                    b.Property<string>("TestType")
-                        .IsRequired()
-                        .HasMaxLength(50)
-                        .HasColumnType("TEXT");
-
-                    b.Property<string>("UserAnswer")
-                        .HasColumnType("TEXT");
-
-                    b.HasKey("Id");
-
-                    b.HasIndex("StudyCardId");
-
-                    b.ToTable("test_results", (string)null);
-                });
-
             modelBuilder.Entity("DramaLing.Api.Models.Entities.User", b =>
                 {
                     b.Property<Guid>("Id")
                         .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
 
                     b.Property<string>("AvatarUrl")
                         .HasColumnType("TEXT")
@@ -1127,7 +882,8 @@ namespace DramaLing.Api.Migrations
             modelBuilder.Entity("DramaLing.Api.Models.Entities.UserAudioPreferences", b =>
                 {
                     b.Property<Guid>("UserId")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
 
                     b.Property<bool>("AutoPlayEnabled")
                         .HasColumnType("INTEGER")
@@ -1180,36 +936,46 @@ namespace DramaLing.Api.Migrations
                 {
                     b.Property<Guid>("Id")
                         .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
 
                     b.Property<bool>("AutoPlayAudio")
-                        .HasColumnType("INTEGER");
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("auto_play_audio");
 
                     b.Property<DateTime>("CreatedAt")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
 
                     b.Property<int>("DailyGoal")
-                        .HasColumnType("INTEGER");
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("daily_goal");
 
                     b.Property<string>("DifficultyPreference")
                         .IsRequired()
                         .HasMaxLength(20)
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("difficulty_preference");
 
                     b.Property<bool>("ReminderEnabled")
-                        .HasColumnType("INTEGER");
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("reminder_enabled");
 
                     b.Property<TimeOnly>("ReminderTime")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("reminder_time");
 
                     b.Property<bool>("ShowPronunciation")
-                        .HasColumnType("INTEGER");
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("show_pronunciation");
 
                     b.Property<DateTime>("UpdatedAt")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
 
                     b.Property<Guid>("UserId")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
 
                     b.HasKey("Id");
 
@@ -1223,34 +989,44 @@ namespace DramaLing.Api.Migrations
                 {
                     b.Property<Guid>("Id")
                         .ValueGeneratedOnAdd()
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
 
                     b.Property<DateTime>("CreatedAt")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
 
                     b.Property<DateOnly>("Date")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("date");
 
                     b.Property<int>("HighValueWordClicks")
-                        .HasColumnType("INTEGER");
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("high_value_word_clicks");
 
                     b.Property<int>("LowValueWordClicks")
-                        .HasColumnType("INTEGER");
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("low_value_word_clicks");
 
                     b.Property<int>("SentenceAnalysisCount")
-                        .HasColumnType("INTEGER");
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("sentence_analysis_count");
 
                     b.Property<int>("TotalApiCalls")
-                        .HasColumnType("INTEGER");
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("total_api_calls");
 
                     b.Property<int>("UniqueWordsQueried")
-                        .HasColumnType("INTEGER");
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("unique_words_queried");
 
                     b.Property<DateTime>("UpdatedAt")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("updated_at");
 
                     b.Property<Guid>("UserId")
-                        .HasColumnType("TEXT");
+                        .HasColumnType("TEXT")
+                        .HasColumnName("user_id");
 
                     b.HasKey("Id");
 
@@ -1261,7 +1037,7 @@ namespace DramaLing.Api.Migrations
                         .IsUnique()
                         .HasDatabaseName("IX_WordQueryUsageStats_UserDate");
 
-                    b.ToTable("WordQueryUsageStats");
+                    b.ToTable("word_query_usage_stats", (string)null);
                 });
 
             modelBuilder.Entity("DramaLing.Api.Models.Entities.DailyStats", b =>
@@ -1383,11 +1159,6 @@ namespace DramaLing.Api.Migrations
                         .HasForeignKey("FlashcardId")
                         .OnDelete(DeleteBehavior.SetNull);
 
-                    b.HasOne("DramaLing.Api.Models.Entities.StudySession", "StudySession")
-                        .WithMany()
-                        .HasForeignKey("StudySessionId")
-                        .OnDelete(DeleteBehavior.SetNull);
-
                     b.HasOne("DramaLing.Api.Models.Entities.User", "User")
                         .WithMany()
                         .HasForeignKey("UserId")
@@ -1396,65 +1167,6 @@ namespace DramaLing.Api.Migrations
 
                     b.Navigation("Flashcard");
 
-                    b.Navigation("StudySession");
-
-                    b.Navigation("User");
-                });
-
-            modelBuilder.Entity("DramaLing.Api.Models.Entities.StudyCard", b =>
-                {
-                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
-                        .WithMany()
-                        .HasForeignKey("FlashcardId")
-                        .OnDelete(DeleteBehavior.Cascade)
-                        .IsRequired();
-
-                    b.HasOne("DramaLing.Api.Models.Entities.StudySession", "StudySession")
-                        .WithMany("StudyCards")
-                        .HasForeignKey("StudySessionId")
-                        .OnDelete(DeleteBehavior.Cascade)
-                        .IsRequired();
-
-                    b.Navigation("Flashcard");
-
-                    b.Navigation("StudySession");
-                });
-
-            modelBuilder.Entity("DramaLing.Api.Models.Entities.StudyRecord", b =>
-                {
-                    b.HasOne("DramaLing.Api.Models.Entities.Flashcard", "Flashcard")
-                        .WithMany("StudyRecords")
-                        .HasForeignKey("FlashcardId")
-                        .OnDelete(DeleteBehavior.Cascade)
-                        .IsRequired();
-
-                    b.HasOne("DramaLing.Api.Models.Entities.StudySession", "Session")
-                        .WithMany("StudyRecords")
-                        .HasForeignKey("SessionId")
-                        .OnDelete(DeleteBehavior.Cascade)
-                        .IsRequired();
-
-                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
-                        .WithMany()
-                        .HasForeignKey("UserId")
-                        .OnDelete(DeleteBehavior.Cascade)
-                        .IsRequired();
-
-                    b.Navigation("Flashcard");
-
-                    b.Navigation("Session");
-
-                    b.Navigation("User");
-                });
-
-            modelBuilder.Entity("DramaLing.Api.Models.Entities.StudySession", b =>
-                {
-                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
-                        .WithMany("StudySessions")
-                        .HasForeignKey("UserId")
-                        .OnDelete(DeleteBehavior.Cascade)
-                        .IsRequired();
-
                     b.Navigation("User");
                 });
 
@@ -1469,17 +1181,6 @@ namespace DramaLing.Api.Migrations
                     b.Navigation("User");
                 });
 
-            modelBuilder.Entity("DramaLing.Api.Models.Entities.TestResult", b =>
-                {
-                    b.HasOne("DramaLing.Api.Models.Entities.StudyCard", "StudyCard")
-                        .WithMany("TestResults")
-                        .HasForeignKey("StudyCardId")
-                        .OnDelete(DeleteBehavior.Cascade)
-                        .IsRequired();
-
-                    b.Navigation("StudyCard");
-                });
-
             modelBuilder.Entity("DramaLing.Api.Models.Entities.UserAudioPreferences", b =>
                 {
                     b.HasOne("DramaLing.Api.Models.Entities.User", "User")
@@ -1525,20 +1226,6 @@ namespace DramaLing.Api.Migrations
                     b.Navigation("FlashcardExampleImages");
 
                     b.Navigation("FlashcardTags");
-
-                    b.Navigation("StudyRecords");
-                });
-
-            modelBuilder.Entity("DramaLing.Api.Models.Entities.StudyCard", b =>
-                {
-                    b.Navigation("TestResults");
-                });
-
-            modelBuilder.Entity("DramaLing.Api.Models.Entities.StudySession", b =>
-                {
-                    b.Navigation("StudyCards");
-
-                    b.Navigation("StudyRecords");
                 });
 
             modelBuilder.Entity("DramaLing.Api.Models.Entities.Tag", b =>
@@ -1555,8 +1242,6 @@ namespace DramaLing.Api.Migrations
                     b.Navigation("Flashcards");
 
                     b.Navigation("Settings");
-
-                    b.Navigation("StudySessions");
                 });
 #pragma warning restore 612, 618
         }
diff --git a/backend/DramaLing.Api/Models/Configuration/GeminiOptions.cs b/backend/DramaLing.Api/Models/Configuration/GeminiOptions.cs
index 9cae548..57947d9 100644
--- a/backend/DramaLing.Api/Models/Configuration/GeminiOptions.cs
+++ b/backend/DramaLing.Api/Models/Configuration/GeminiOptions.cs
@@ -9,19 +9,37 @@ public class GeminiOptions
     [Required(ErrorMessage = "Gemini API Key is required")]
     public string ApiKey { get; set; } = string.Empty;
 
+    /// <summary>
+    /// API 請求超時時間（秒）
+    /// </summary>
     [Range(1, 120, ErrorMessage = "Timeout must be between 1 and 120 seconds")]
     public int TimeoutSeconds { get; set; } = 30;
 
+    /// <summary>
+    /// API 請求最大重試次數
+    /// </summary>
     [Range(1, 10, ErrorMessage = "Max retries must be between 1 and 10")]
     public int MaxRetries { get; set; } = 3;
 
+    /// <summary>
+    /// AI 回應最大 Token 數量
+    /// </summary>
     [Range(100, 10000, ErrorMessage = "Max tokens must be between 100 and 10000")]
     public int MaxOutputTokens { get; set; } = 2000;
 
+    /// <summary>
+    /// AI 回應的隨機性程度（0.0-2.0）
+    /// </summary>
     [Range(0.0, 2.0, ErrorMessage = "Temperature must be between 0 and 2")]
     public double Temperature { get; set; } = 0.7;
 
-    public string Model { get; set; } = "gemini-1.5-flash";
+    /// <summary>
+    /// 使用的 Gemini 模型名稱
+    /// </summary>
+    public string Model { get; set; } = "gemini-2.0-flash";
 
+    /// <summary>
+    /// Gemini API 基本 URL
+    /// </summary>
     public string BaseUrl { get; set; } = "https://generativelanguage.googleapis.com";
 }
\ No newline at end of file
diff --git a/backend/DramaLing.Api/Program.cs b/backend/DramaLing.Api/Program.cs
index ac7f499..55b4d9b 100644
--- a/backend/DramaLing.Api/Program.cs
+++ b/backend/DramaLing.Api/Program.cs
@@ -26,17 +26,27 @@ builder.Services.Configure<ReplicateOptions>(
     builder.Configuration.GetSection(ReplicateOptions.SectionName));
 builder.Services.AddSingleton<IValidateOptions<ReplicateOptions>, ReplicateOptionsValidator>();
 
-// 在開發環境設定測試用的API Key
-if (builder.Environment.IsDevelopment() &&
-    string.IsNullOrEmpty(Environment.GetEnvironmentVariable("GEMINI_API_KEY")))
+// 在開發環境設定 API Key - 修復配置讀取邏輯
+if (builder.Environment.IsDevelopment())
 {
     builder.Services.PostConfigure<GeminiOptions>(options =>
     {
+        // 只有當 ApiKey 未設置時才嘗試從其他來源讀取
         if (string.IsNullOrEmpty(options.ApiKey))
         {
-            options.ApiKey = Environment.GetEnvironmentVariable("GEMINI_API_KEY")
-                           ?? builder.Configuration["Gemini:ApiKey"]
-                           ?? "test-key";
+            // 優先從環境變數讀取
+            var envApiKey = Environment.GetEnvironmentVariable("GEMINI_API_KEY");
+            if (!string.IsNullOrEmpty(envApiKey))
+            {
+                options.ApiKey = envApiKey;
+            }
+            // 如果環境變數沒有，Configuration 應該已經包含 user-secrets
+            // 這裡只是作為後備，不應該覆蓋已經從 user-secrets 載入的設定
+            else if (string.IsNullOrEmpty(builder.Configuration["Gemini:ApiKey"]))
+            {
+                // 只有在真的沒有任何配置時才使用測試金鑰
+                options.ApiKey = "test-key";
+            }
         }
     });
 }
diff --git a/backend/DramaLing.Api/appsettings.json b/backend/DramaLing.Api/appsettings.json
index e33ea80..cc80520 100644
--- a/backend/DramaLing.Api/appsettings.json
+++ b/backend/DramaLing.Api/appsettings.json
@@ -19,15 +19,6 @@
   "Frontend": {
     "Urls": ["http://localhost:3000", "http://localhost:3001"]
   },
-  "Gemini": {
-    "ApiKey": "",
-    "TimeoutSeconds": 30,
-    "MaxRetries": 3,
-    "MaxOutputTokens": 2000,
-    "Temperature": 0.7,
-    "Model": "gemini-1.5-flash",
-    "BaseUrl": "https://generativelanguage.googleapis.com"
-  },
   "Replicate": {
     "ApiKey": "",
     "BaseUrl": "https://api.replicate.com/v1",