diff --git a/backend/DramaLing.Api/Controllers/FlashcardsController.cs b/backend/DramaLing.Api/Controllers/FlashcardsController.cs
index 036c4fb..a05d5f0 100644
--- a/backend/DramaLing.Api/Controllers/FlashcardsController.cs
+++ b/backend/DramaLing.Api/Controllers/FlashcardsController.cs
@@ -260,6 +260,9 @@ public class FlashcardsController : ControllerBase
                 Pronunciation = request.Pronunciation,
                 Example = request.Example,
                 ExampleTranslation = request.ExampleTranslation,
+                Synonyms = request.Synonyms != null && request.Synonyms.Any()
+                    ? System.Text.Json.JsonSerializer.Serialize(request.Synonyms)
+                    : null,
                 MasteryLevel = 0,
                 TimesReviewed = 0,
                 IsFavorite = false,
@@ -671,4 +674,5 @@ public class CreateFlashcardRequest
     public string Pronunciation { get; set; } = string.Empty;
     public string Example { get; set; } = string.Empty;
     public string? ExampleTranslation { get; set; }
+    public List<string>? Synonyms { get; set; }
 }
\ No newline at end of file
diff --git a/backend/DramaLing.Api/Migrations/20250928080858_AddSynonymsToFlashcard.Designer.cs b/backend/DramaLing.Api/Migrations/20250928080858_AddSynonymsToFlashcard.Designer.cs
new file mode 100644
index 0000000..365b8b2
--- /dev/null
+++ b/backend/DramaLing.Api/Migrations/20250928080858_AddSynonymsToFlashcard.Designer.cs
@@ -0,0 +1,1504 @@
+// <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("20250928080858_AddSynonymsToFlashcard")]
+    partial class AddSynonymsToFlashcard
+    {
+        /// <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")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    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");
+
+                    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");
+
+                    b.Property<bool>("IsFavorite")
+                        .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")
+                        .HasColumnName("part_of_speech");
+
+                    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");
+
+                    b.Property<string>("Translation")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    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");
+
+                    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.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<Guid?>("StudySessionId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("study_session_id");
+
+                    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("StudySessionId")
+                        .HasDatabaseName("IX_PronunciationAssessment_Session");
+
+                    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.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);
+                });
+
+            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.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");
+
+                    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.StudySession", "StudySession")
+                        .WithMany()
+                        .HasForeignKey("StudySessionId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("DramaLing.Api.Models.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    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");
+                });
+
+            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.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")
+                        .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");
+
+                    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 =>
+                {
+                    b.Navigation("FlashcardTags");
+                });
+
+            modelBuilder.Entity("DramaLing.Api.Models.Entities.User", b =>
+                {
+                    b.Navigation("DailyStats");
+
+                    b.Navigation("ErrorReports");
+
+                    b.Navigation("Flashcards");
+
+                    b.Navigation("Settings");
+
+                    b.Navigation("StudySessions");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}
diff --git a/backend/DramaLing.Api/Migrations/20250928080858_AddSynonymsToFlashcard.cs b/backend/DramaLing.Api/Migrations/20250928080858_AddSynonymsToFlashcard.cs
new file mode 100644
index 0000000..a6efd9d
--- /dev/null
+++ b/backend/DramaLing.Api/Migrations/20250928080858_AddSynonymsToFlashcard.cs
@@ -0,0 +1,29 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace DramaLing.Api.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddSynonymsToFlashcard : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<string>(
+                name: "Synonyms",
+                table: "flashcards",
+                type: "TEXT",
+                maxLength: 2000,
+                nullable: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "Synonyms",
+                table: "flashcards");
+        }
+    }
+}
diff --git a/backend/DramaLing.Api/Migrations/DramaLingDbContextModelSnapshot.cs b/backend/DramaLing.Api/Migrations/DramaLingDbContextModelSnapshot.cs
index 5156a2b..4bf9d3e 100644
--- a/backend/DramaLing.Api/Migrations/DramaLingDbContextModelSnapshot.cs
+++ b/backend/DramaLing.Api/Migrations/DramaLingDbContextModelSnapshot.cs
@@ -372,6 +372,10 @@ namespace DramaLing.Api.Migrations
                     b.Property<string>("ReviewHistory")
                         .HasColumnType("TEXT");
 
+                    b.Property<string>("Synonyms")
+                        .HasMaxLength(2000)
+                        .HasColumnType("TEXT");
+
                     b.Property<int>("TimesCorrect")
                         .HasColumnType("INTEGER")
                         .HasColumnName("times_correct");
diff --git a/backend/DramaLing.Api/Models/Entities/Flashcard.cs b/backend/DramaLing.Api/Models/Entities/Flashcard.cs
index 32b68b1..a350657 100644
--- a/backend/DramaLing.Api/Models/Entities/Flashcard.cs
+++ b/backend/DramaLing.Api/Models/Entities/Flashcard.cs
@@ -32,6 +32,9 @@ public class Flashcard
     [MaxLength(1000)]
     public string? FilledQuestionText { get; set; }
 
+    [MaxLength(2000)]
+    public string? Synonyms { get; set; } // JSON 格式儲存同義詞列表
+
     // SM-2 算法參數
     public float EasinessFactor { get; set; } = 2.5f;