src/NexusReader.Application/Abstractions/Services/IUserPreferenceStore.cs

@@ -0,0 +1,10 @@
+using FluentResults;
+using NexusReader.Domain.Enums;
+
+namespace NexusReader.Application.Abstractions.Services;
+
+public interface IUserPreferenceStore
+{
+    Task<Result> SaveThemePreferenceAsync(ThemeMode mode);
+    Task<Result<ThemeMode>> GetThemePreferenceAsync();
+}

src/NexusReader.Application/Commands/User/UpdateThemeCommand.cs

@@ -0,0 +1,6 @@
+using NexusReader.Application.Abstractions.Messaging;
+using NexusReader.Domain.Enums;
+
+namespace NexusReader.Application.Commands.User;
+
+public record UpdateThemeCommand(string UserId, ThemeMode Mode) : ICommand;

src/NexusReader.Application/Commands/User/UpdateThemeCommandHandler.cs

@@ -0,0 +1,41 @@
+using FluentResults;
+using Microsoft.EntityFrameworkCore;
+using NexusReader.Application.Abstractions.Messaging;
+using NexusReader.Data.Persistence;
+
+namespace NexusReader.Application.Commands.User;
+
+public class UpdateThemeCommandHandler : ICommandHandler<UpdateThemeCommand>
+{
+    private readonly IDbContextFactory<AppDbContext> _dbContextFactory;
+
+    public UpdateThemeCommandHandler(IDbContextFactory<AppDbContext> dbContextFactory)
+    {
+        _dbContextFactory = dbContextFactory;
+    }
+
+    public async Task<Result> Handle(UpdateThemeCommand request, CancellationToken cancellationToken)
+    {
+        try
+        {
+            using var dbContext = await _dbContextFactory.CreateDbContextAsync(cancellationToken);
+            var user = await dbContext.Users
+                .AsTracking()
+                .FirstOrDefaultAsync(u => u.Id == request.UserId, cancellationToken);
+                
+            if (user == null)
+            {
+                return Result.Fail("User not found.");
+            }
+
+            user.ThemePreference = request.Mode;
+            await dbContext.SaveChangesAsync(cancellationToken);
+            
+            return Result.Ok();
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error("Failed to save theme preference in database.").CausedBy(ex));
+        }
+    }
+}

src/NexusReader.Application/Common/AppJsonContext.cs

@@ -16,6 +16,8 @@ namespace NexusReader.Application.Common;
 [JsonSerializable(typeof(NexusReader.Application.Queries.Recommendations.ContextualRecommendationResponse))]
 [JsonSerializable(typeof(NexusReader.Application.Queries.Recommendations.RecommendationDto))]
 [JsonSerializable(typeof(List<NexusReader.Application.Queries.Recommendations.RecommendationDto>))]
+[JsonSerializable(typeof(NexusReader.Application.DTOs.User.UpdateThemeRequest))]
+[JsonSerializable(typeof(NexusReader.Domain.Enums.ThemeMode))]
 public partial class AppJsonContext : JsonSerializerContext
 {
 }

src/NexusReader.Application/DTOs/User/UpdateThemeRequest.cs

@@ -0,0 +1,5 @@
+using NexusReader.Domain.Enums;
+
+namespace NexusReader.Application.DTOs.User;
+
+public record UpdateThemeRequest(ThemeMode Mode);

src/NexusReader.Application/DTOs/User/UserProfileDto.cs

@@ -1,4 +1,5 @@
 using NexusReader.Application.Constants;
+using NexusReader.Domain.Enums;
 
 namespace NexusReader.Application.DTOs.User;
 
@@ -8,6 +9,7 @@ public record UserProfileDto
     public string UserId { get; init; } = string.Empty;
     public int AITokensUsed { get; init; }
     public Guid TenantId { get; init; }
+    public ThemeMode ThemePreference { get; init; } = ThemeMode.System;
     
     /// <summary>
     /// Relational data for the current subscription plan.

src/NexusReader.Application/Queries/User/GetUserProfileQueryHandler.cs

@@ -27,6 +27,7 @@ public class GetUserProfileQueryHandler : IRequestHandler<GetUserProfileQuery, R
                 UserId = u.Id,
                 AITokensUsed = u.AITokensUsed,
                 TenantIdString = u.TenantId,
+                ThemePreference = u.ThemePreference,
                 Plan = u.SubscriptionPlan != null ? new SubscriptionPlanDto
                 {
                     Id = u.SubscriptionPlan.Id,
@@ -106,6 +107,7 @@ public class GetUserProfileQueryHandler : IRequestHandler<GetUserProfileQuery, R
             AverageQuizScore = averageQuizScore,
             DisplayName = userRaw.DisplayName,
             BooksReadCount = userRaw.BooksReadCount,
+            ThemePreference = userRaw.ThemePreference,
             ConceptsMappedCount = conceptsMappedCount,
             LastReadBook = userRaw.LastReadBook,
             RecentQuizzes = userRaw.QuizResults.OrderByDescending(q => q.CompletedDate).Take(5).Select(q => new QuizResultDto

src/NexusReader.Data/Migrations/20260607104453_AddThemePreference.Designer.cs

@@ -0,0 +1,711 @@
+// <auto-generated />
+using System;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using NexusReader.Data.Persistence;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+
+#nullable disable
+
+namespace NexusReader.Data.Migrations
+{
+    [DbContext(typeof(AppDbContext))]
+    [Migration("20260607104453_AddThemePreference")]
+    partial class AddThemePreference
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasAnnotation("ProductVersion", "10.0.7")
+                .HasAnnotation("Relational:MaxIdentifierLength", 63);
+
+            NpgsqlModelBuilderExtensions.UseIdentityByDefaultColumns(modelBuilder);
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityRole", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("text");
+
+                    b.Property<string>("ConcurrencyStamp")
+                        .IsConcurrencyToken()
+                        .HasColumnType("text");
+
+                    b.Property<string>("Name")
+                        .HasMaxLength(256)
+                        .HasColumnType("character varying(256)");
+
+                    b.Property<string>("NormalizedName")
+                        .HasMaxLength(256)
+                        .HasColumnType("character varying(256)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("NormalizedName")
+                        .IsUnique()
+                        .HasDatabaseName("RoleNameIndex");
+
+                    b.ToTable("AspNetRoles", (string)null);
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityRoleClaim<string>", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("Id"));
+
+                    b.Property<string>("ClaimType")
+                        .HasColumnType("text");
+
+                    b.Property<string>("ClaimValue")
+                        .HasColumnType("text");
+
+                    b.Property<string>("RoleId")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("RoleId");
+
+                    b.ToTable("AspNetRoleClaims", (string)null);
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserClaim<string>", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("Id"));
+
+                    b.Property<string>("ClaimType")
+                        .HasColumnType("text");
+
+                    b.Property<string>("ClaimValue")
+                        .HasColumnType("text");
+
+                    b.Property<string>("UserId")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("AspNetUserClaims", (string)null);
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserLogin<string>", b =>
+                {
+                    b.Property<string>("LoginProvider")
+                        .HasColumnType("text");
+
+                    b.Property<string>("ProviderKey")
+                        .HasColumnType("text");
+
+                    b.Property<string>("ProviderDisplayName")
+                        .HasColumnType("text");
+
+                    b.Property<string>("UserId")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.HasKey("LoginProvider", "ProviderKey");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("AspNetUserLogins", (string)null);
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserRole<string>", b =>
+                {
+                    b.Property<string>("UserId")
+                        .HasColumnType("text");
+
+                    b.Property<string>("RoleId")
+                        .HasColumnType("text");
+
+                    b.HasKey("UserId", "RoleId");
+
+                    b.HasIndex("RoleId");
+
+                    b.ToTable("AspNetUserRoles", (string)null);
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserToken<string>", b =>
+                {
+                    b.Property<string>("UserId")
+                        .HasColumnType("text");
+
+                    b.Property<string>("LoginProvider")
+                        .HasColumnType("text");
+
+                    b.Property<string>("Name")
+                        .HasColumnType("text");
+
+                    b.Property<string>("Value")
+                        .HasColumnType("text");
+
+                    b.HasKey("UserId", "LoginProvider", "Name");
+
+                    b.ToTable("AspNetUserTokens", (string)null);
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.Author", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("Id"));
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("character varying(255)");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("Authors");
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.Ebook", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("uuid");
+
+                    b.Property<DateTime>("AddedDate")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<int>("AuthorId")
+                        .HasColumnType("integer");
+
+                    b.Property<string>("CoverUrl")
+                        .HasColumnType("text");
+
+                    b.Property<string>("Description")
+                        .HasColumnType("text");
+
+                    b.Property<string>("FilePath")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.Property<bool>("IsReadyForReading")
+                        .HasColumnType("boolean");
+
+                    b.Property<string>("LastChapter")
+                        .HasMaxLength(255)
+                        .HasColumnType("character varying(255)");
+
+                    b.Property<int>("LastChapterIndex")
+                        .HasColumnType("integer");
+
+                    b.Property<DateTime?>("LastReadDate")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<double>("Progress")
+                        .HasColumnType("double precision");
+
+                    b.Property<string>("TenantId")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("character varying(128)");
+
+                    b.Property<string>("Title")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("character varying(255)");
+
+                    b.Property<string>("UserId")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("AuthorId");
+
+                    b.HasIndex("TenantId");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("Ebooks");
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.KnowledgeUnit", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasMaxLength(128)
+                        .HasColumnType("character varying(128)");
+
+                    b.Property<string>("Content")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<Guid?>("EbookId")
+                        .HasColumnType("uuid");
+
+                    b.Property<string>("MetadataJson")
+                        .HasColumnType("text");
+
+                    b.Property<string>("TenantId")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("character varying(128)");
+
+                    b.Property<int>("Type")
+                        .HasColumnType("integer");
+
+                    b.Property<string>("Version")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("character varying(50)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("EbookId");
+
+                    b.HasIndex("TenantId");
+
+                    b.ToTable("KnowledgeUnits");
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.KnowledgeUnitLink", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("Id"));
+
+                    b.Property<string>("RelationType")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("character varying(50)");
+
+                    b.Property<string>("SourceUnitId")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("character varying(128)");
+
+                    b.Property<string>("TargetUnitId")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("character varying(128)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("SourceUnitId");
+
+                    b.HasIndex("TargetUnitId");
+
+                    b.ToTable("KnowledgeUnitLinks");
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.NexusUser", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("text");
+
+                    b.Property<int>("AITokenLimit")
+                        .HasColumnType("integer");
+
+                    b.Property<int>("AITokensUsed")
+                        .HasColumnType("integer");
+
+                    b.Property<int>("AccessFailedCount")
+                        .HasColumnType("integer");
+
+                    b.Property<string>("ConcurrencyStamp")
+                        .IsConcurrencyToken()
+                        .HasColumnType("text");
+
+                    b.Property<string>("DisplayName")
+                        .HasMaxLength(100)
+                        .HasColumnType("character varying(100)");
+
+                    b.Property<string>("Email")
+                        .HasMaxLength(256)
+                        .HasColumnType("character varying(256)");
+
+                    b.Property<bool>("EmailConfirmed")
+                        .HasColumnType("boolean");
+
+                    b.Property<DateTime?>("LastAiActionDate")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<DateTime?>("LastReadAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("LastReadPageId")
+                        .HasMaxLength(255)
+                        .HasColumnType("character varying(255)");
+
+                    b.Property<bool>("LockoutEnabled")
+                        .HasColumnType("boolean");
+
+                    b.Property<DateTimeOffset?>("LockoutEnd")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("NormalizedEmail")
+                        .HasMaxLength(256)
+                        .HasColumnType("character varying(256)");
+
+                    b.Property<string>("NormalizedUserName")
+                        .HasMaxLength(256)
+                        .HasColumnType("character varying(256)");
+
+                    b.Property<string>("PasswordHash")
+                        .HasColumnType("text");
+
+                    b.Property<string>("PhoneNumber")
+                        .HasColumnType("text");
+
+                    b.Property<bool>("PhoneNumberConfirmed")
+                        .HasColumnType("boolean");
+
+                    b.Property<string>("SecurityStamp")
+                        .HasColumnType("text");
+
+                    b.Property<int>("SubscriptionPlanId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer")
+                        .HasDefaultValue(1);
+
+                    b.Property<string>("TenantId")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("character varying(128)");
+
+                    b.Property<int>("ThemePreference")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer")
+                        .HasDefaultValue(0);
+
+                    b.Property<bool>("TwoFactorEnabled")
+                        .HasColumnType("boolean");
+
+                    b.Property<string>("UserName")
+                        .HasMaxLength(256)
+                        .HasColumnType("character varying(256)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("NormalizedEmail")
+                        .HasDatabaseName("EmailIndex");
+
+                    b.HasIndex("NormalizedUserName")
+                        .IsUnique()
+                        .HasDatabaseName("UserNameIndex");
+
+                    b.HasIndex("SubscriptionPlanId");
+
+                    b.HasIndex("TenantId");
+
+                    b.ToTable("AspNetUsers", (string)null);
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.QuizResult", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("uuid");
+
+                    b.Property<DateTime>("CompletedDate")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<int>("Score")
+                        .HasColumnType("integer");
+
+                    b.Property<string>("TenantId")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("character varying(128)");
+
+                    b.Property<string>("Topic")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.Property<int>("TotalQuestions")
+                        .HasColumnType("integer");
+
+                    b.Property<string>("UserId")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("TenantId");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("QuizResults");
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.SemanticKnowledgeCache", b =>
+                {
+                    b.Property<string>("ContentHash")
+                        .HasMaxLength(128)
+                        .HasColumnType("character varying(128)");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("JsonData")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.Property<string>("ModelId")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("character varying(50)");
+
+                    b.Property<string>("OriginalText")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.Property<string>("PromptVersion")
+                        .IsRequired()
+                        .HasMaxLength(10)
+                        .HasColumnType("character varying(10)");
+
+                    b.Property<string>("TenantId")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("character varying(128)");
+
+                    b.HasKey("ContentHash");
+
+                    b.HasIndex("ContentHash")
+                        .IsUnique();
+
+                    b.HasIndex("TenantId");
+
+                    b.ToTable("SemanticKnowledgeCache");
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.SubscriptionPlan", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("Id"));
+
+                    b.Property<int>("AITokenLimit")
+                        .HasColumnType("integer");
+
+                    b.Property<bool>("IsUnlimitedTokens")
+                        .HasColumnType("boolean");
+
+                    b.Property<decimal>("MonthlyPrice")
+                        .HasColumnType("numeric");
+
+                    b.Property<string>("PlanName")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("character varying(50)");
+
+                    b.Property<string>("StripeProductId")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("character varying(50)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("PlanName")
+                        .IsUnique();
+
+                    b.ToTable("SubscriptionPlans");
+
+                    b.HasData(
+                        new
+                        {
+                            Id = 1,
+                            AITokenLimit = 5000,
+                            IsUnlimitedTokens = false,
+                            MonthlyPrice = 0m,
+                            PlanName = "Free",
+                            StripeProductId = "prod_Free789"
+                        },
+                        new
+                        {
+                            Id = 2,
+                            AITokenLimit = 10000,
+                            IsUnlimitedTokens = false,
+                            MonthlyPrice = 9.99m,
+                            PlanName = "Basic",
+                            StripeProductId = "prod_basic_placeholder"
+                        },
+                        new
+                        {
+                            Id = 3,
+                            AITokenLimit = 50000,
+                            IsUnlimitedTokens = false,
+                            MonthlyPrice = 19.99m,
+                            PlanName = "Pro",
+                            StripeProductId = "prod_pro_placeholder"
+                        },
+                        new
+                        {
+                            Id = 4,
+                            AITokenLimit = 1000000000,
+                            IsUnlimitedTokens = true,
+                            MonthlyPrice = 99.99m,
+                            PlanName = "Enterprise",
+                            StripeProductId = "prod_enterprise_placeholder"
+                        });
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityRoleClaim<string>", b =>
+                {
+                    b.HasOne("Microsoft.AspNetCore.Identity.IdentityRole", null)
+                        .WithMany()
+                        .HasForeignKey("RoleId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserClaim<string>", b =>
+                {
+                    b.HasOne("NexusReader.Domain.Entities.NexusUser", null)
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserLogin<string>", b =>
+                {
+                    b.HasOne("NexusReader.Domain.Entities.NexusUser", null)
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserRole<string>", b =>
+                {
+                    b.HasOne("Microsoft.AspNetCore.Identity.IdentityRole", null)
+                        .WithMany()
+                        .HasForeignKey("RoleId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("NexusReader.Domain.Entities.NexusUser", null)
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserToken<string>", b =>
+                {
+                    b.HasOne("NexusReader.Domain.Entities.NexusUser", null)
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.Ebook", b =>
+                {
+                    b.HasOne("NexusReader.Domain.Entities.Author", "Author")
+                        .WithMany("Ebooks")
+                        .HasForeignKey("AuthorId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.HasOne("NexusReader.Domain.Entities.NexusUser", "User")
+                        .WithMany("Ebooks")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Author");
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.KnowledgeUnit", b =>
+                {
+                    b.HasOne("NexusReader.Domain.Entities.Ebook", "Ebook")
+                        .WithMany()
+                        .HasForeignKey("EbookId")
+                        .OnDelete(DeleteBehavior.Cascade);
+
+                    b.Navigation("Ebook");
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.KnowledgeUnitLink", b =>
+                {
+                    b.HasOne("NexusReader.Domain.Entities.KnowledgeUnit", "SourceUnit")
+                        .WithMany("OutgoingLinks")
+                        .HasForeignKey("SourceUnitId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("NexusReader.Domain.Entities.KnowledgeUnit", "TargetUnit")
+                        .WithMany("IncomingLinks")
+                        .HasForeignKey("TargetUnitId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("SourceUnit");
+
+                    b.Navigation("TargetUnit");
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.NexusUser", b =>
+                {
+                    b.HasOne("NexusReader.Domain.Entities.SubscriptionPlan", "SubscriptionPlan")
+                        .WithMany()
+                        .HasForeignKey("SubscriptionPlanId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.Navigation("SubscriptionPlan");
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.QuizResult", b =>
+                {
+                    b.HasOne("NexusReader.Domain.Entities.NexusUser", "User")
+                        .WithMany("QuizResults")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.Author", b =>
+                {
+                    b.Navigation("Ebooks");
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.KnowledgeUnit", b =>
+                {
+                    b.Navigation("IncomingLinks");
+
+                    b.Navigation("OutgoingLinks");
+                });
+
+            modelBuilder.Entity("NexusReader.Domain.Entities.NexusUser", b =>
+                {
+                    b.Navigation("Ebooks");
+
+                    b.Navigation("QuizResults");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

src/NexusReader.Data/Migrations/20260607104453_AddThemePreference.cs

@@ -0,0 +1,56 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+using Pgvector;
+
+#nullable disable
+
+namespace NexusReader.Data.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddThemePreference : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "Vector",
+                table: "SemanticKnowledgeCache");
+
+            migrationBuilder.DropColumn(
+                name: "Vector",
+                table: "KnowledgeUnits");
+
+            migrationBuilder.AlterDatabase()
+                .OldAnnotation("Npgsql:PostgresExtension:vector", ",,");
+
+            migrationBuilder.AddColumn<int>(
+                name: "ThemePreference",
+                table: "AspNetUsers",
+                type: "integer",
+                nullable: false,
+                defaultValue: 0);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "ThemePreference",
+                table: "AspNetUsers");
+
+            migrationBuilder.AlterDatabase()
+                .Annotation("Npgsql:PostgresExtension:vector", ",,");
+
+            migrationBuilder.AddColumn<Vector>(
+                name: "Vector",
+                table: "SemanticKnowledgeCache",
+                type: "vector(1536)",
+                nullable: true);
+
+            migrationBuilder.AddColumn<Vector>(
+                name: "Vector",
+                table: "KnowledgeUnits",
+                type: "vector(768)",
+                nullable: true);
+        }
+    }
+}

src/NexusReader.Data/Migrations/AppDbContextModelSnapshot.cs

@@ -5,7 +5,6 @@ using Microsoft.EntityFrameworkCore.Infrastructure;
 using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
 using NexusReader.Data.Persistence;
 using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
-using Pgvector;
 
 #nullable disable
 
@@ -21,7 +20,6 @@ namespace NexusReader.Data.Migrations
                 .HasAnnotation("ProductVersion", "10.0.7")
                 .HasAnnotation("Relational:MaxIdentifierLength", 63);
 
-            NpgsqlModelBuilderExtensions.HasPostgresExtension(modelBuilder, "vector");
             NpgsqlModelBuilderExtensions.UseIdentityByDefaultColumns(modelBuilder);
 
             modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityRole", b =>
@@ -264,9 +262,6 @@ namespace NexusReader.Data.Migrations
                     b.Property<int>("Type")
                         .HasColumnType("integer");
 
-                    b.Property<Vector>("Vector")
-                        .HasColumnType("vector(768)");
-
                     b.Property<string>("Version")
                         .IsRequired()
                         .HasMaxLength(50)
@@ -388,6 +383,11 @@ namespace NexusReader.Data.Migrations
                         .HasMaxLength(128)
                         .HasColumnType("character varying(128)");
 
+                    b.Property<int>("ThemePreference")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer")
+                        .HasDefaultValue(0);
+
                     b.Property<bool>("TwoFactorEnabled")
                         .HasColumnType("boolean");
 
@@ -480,9 +480,6 @@ namespace NexusReader.Data.Migrations
                         .HasMaxLength(128)
                         .HasColumnType("character varying(128)");
 
-                    b.Property<Vector>("Vector")
-                        .HasColumnType("vector(1536)");
-
                     b.HasKey("ContentHash");
 
                     b.HasIndex("ContentHash")

src/NexusReader.Data/Persistence/AppDbContext.cs

@@ -1,6 +1,7 @@
 using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore;
 using NexusReader.Domain.Entities;
+using NexusReader.Domain.Enums;
 
 namespace NexusReader.Data.Persistence;
 
@@ -43,6 +44,10 @@ public class AppDbContext : IdentityDbContext<NexusUser>
             // Note: DefaultValue for int is 1 (which corresponds to 'Free' in our seed)
             entity.Property(u => u.SubscriptionPlanId)
                 .HasDefaultValue(1);
+
+            entity.Property(u => u.ThemePreference)
+                .HasConversion<int>()
+                .HasDefaultValue(ThemeMode.System);
         });
 
         modelBuilder.Entity<SubscriptionPlan>(entity =>

src/NexusReader.Domain/Entities/NexusUser.cs

@@ -1,6 +1,7 @@
 using Microsoft.AspNetCore.Identity;
 using System.ComponentModel.DataAnnotations;
 using System.ComponentModel.DataAnnotations.Schema;
+using NexusReader.Domain.Enums;
 
 namespace NexusReader.Domain.Entities;
 
@@ -65,4 +66,9 @@ public class NexusUser : IdentityUser
     /// Last read timestamp.
     /// </summary>
     public DateTime? LastReadAt { get; set; }
+
+    /// <summary>
+    /// User's visual theme preference.
+    /// </summary>
+    public ThemeMode ThemePreference { get; set; } = ThemeMode.System;
 }

src/NexusReader.Domain/Enums/ThemeMode.cs

@@ -0,0 +1,8 @@
+namespace NexusReader.Domain.Enums;
+
+public enum ThemeMode
+{
+    System = 0,
+    Dark = 1,
+    LightSepia = 2
+}

src/NexusReader.Maui/MauiProgram.cs

@@ -8,6 +8,7 @@ using NexusReader.Application;
 using MediatR;
 using NexusReader.Maui.Infrastructure.Logging;
 using NexusReader.Maui.Infrastructure.Identity;
+using NexusReader.Maui.Services;
 
 namespace NexusReader.Maui;
 
@@ -44,7 +45,7 @@ public static class MauiProgram
 
 			// Minimal Infrastructure
 			builder.Services.AddSingleton<IPlatformService, MauiPlatformService>();
-			builder.Services.AddSingleton<INativeStorageService, MauiStorageService>();
+			builder.Services.AddSingleton<INativeStorageService, NexusReader.Infrastructure.Mobile.Services.MauiStorageService>();
 			
 			// Minimal Identity (Safe Mode)
 			builder.Services.AddScoped<NexusAuthenticationStateProvider>();
@@ -67,7 +68,8 @@ public static class MauiProgram
 			var featureSettings = builder.Configuration.GetSection("Features").Get<FeatureSettings>() ?? new FeatureSettings();
 			builder.Services.AddSingleton(featureSettings);
 
-			builder.Services.AddScoped<IThemeService, ThemeService>();
+			builder.Services.AddSingleton<IUserPreferenceStore, MauiUserPreferenceStore>();
+			builder.Services.AddSingleton<IThemeService, ThemeService>();
 			builder.Services.AddScoped<IFocusModeService, FocusModeService>();
 			builder.Services.AddScoped<IQuizStateService, QuizStateService>();
 			builder.Services.AddScoped<IReaderNavigationService, ReaderNavigationService>();

src/NexusReader.Maui/Services/MauiUserPreferenceStore.cs

@@ -0,0 +1,61 @@
+using System.Net.Http;
+using System.Net.Http.Json;
+using FluentResults;
+using NexusReader.Application.DTOs.User;
+using NexusReader.Domain.Enums;
+using NexusReader.Application.Abstractions.Services;
+
+namespace NexusReader.Maui.Services;
+
+public class MauiUserPreferenceStore : IUserPreferenceStore
+{
+    private readonly IHttpClientFactory _httpClientFactory;
+
+    public MauiUserPreferenceStore(IHttpClientFactory httpClientFactory)
+    {
+        _httpClientFactory = httpClientFactory;
+    }
+
+    private HttpClient CreateClient() => _httpClientFactory.CreateClient("NexusAPI");
+
+    public async Task<Result> SaveThemePreferenceAsync(ThemeMode mode)
+    {
+        try
+        {
+            var client = CreateClient();
+            var response = await client.PostAsJsonAsync("identity/theme", new UpdateThemeRequest(mode));
+            if (response.IsSuccessStatusCode)
+            {
+                return Result.Ok();
+            }
+            
+            var error = await response.Content.ReadAsStringAsync();
+            return Result.Fail($"Failed to save cloud theme preference on mobile: {error}");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error("Network error saving mobile theme preference to cloud.").CausedBy(ex));
+        }
+    }
+
+    public async Task<Result<ThemeMode>> GetThemePreferenceAsync()
+    {
+        try
+        {
+            var client = CreateClient();
+            var response = await client.GetAsync("identity/profile");
+            if (response.IsSuccessStatusCode)
+            {
+                var profile = await response.Content.ReadFromJsonAsync<UserProfileDto>();
+                return profile != null 
+                    ? Result.Ok(profile.ThemePreference) 
+                    : Result.Fail("Failed to deserialize mobile profile response.");
+            }
+            return Result.Fail($"Failed to fetch theme preference from cloud on mobile: {response.ReasonPhrase}");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error("Network error retrieving theme preference on mobile.").CausedBy(ex));
+        }
+    }
+}

src/NexusReader.Maui/wwwroot/index.html

@@ -9,14 +9,29 @@
     <link rel="icon" type="image/png" href="favicon.png" />
     <script>
         (function () {
-            const savedTheme = localStorage.getItem('theme');
+            try {
-            const systemPrefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
+                var themeMode = localStorage.getItem('theme-mode');
-            const isLight = savedTheme === 'light' || (!savedTheme && !systemPrefersDark);
+                var savedTheme = localStorage.getItem('theme');
+                var isLight = false;
+                
+                if (themeMode === '2' || savedTheme === 'light') {
+                    isLight = true;
+                } else if (themeMode === '1' || savedTheme === 'dark') {
+                    isLight = false;
+                } else {
+                    isLight = window.matchMedia && window.matchMedia('(prefers-color-scheme: light)').matches;
+                }
+                
                 if (isLight) {
                     document.documentElement.classList.add('theme-light');
+                    document.documentElement.classList.remove('theme-dark');
                 } else {
+                    document.documentElement.classList.add('theme-dark');
                     document.documentElement.classList.remove('theme-light');
                 }
+            } catch (e) {
+                // Fail silently
+            }
         })();
     </script>
 </head>

src/NexusReader.UI.Shared/Components/Molecules/AiResponseRenderer.razor.css

@@ -30,17 +30,17 @@
 }
 
 .user-row .message-avatar {
-    background: linear-gradient(135deg, rgba(255, 255, 255, 0.15) 0%, rgba(255, 255, 255, 0.05) 100%);
+    background: var(--bg-surface);
-    color: #ffffff;
+    color: var(--text-main);
-    border: 1px solid rgba(255, 255, 255, 0.2);
+    border: 1px solid var(--border);
-    box-shadow: 0 0 10px rgba(255, 255, 255, 0.1);
+    box-shadow: 0 0 10px var(--border);
 }
 
 .ai-row .message-avatar {
     background: linear-gradient(135deg, #005f38 0%, #004024 100%);
     color: #e6fffa;
-    border: 1px solid rgba(0, 255, 153, 0.4);
+    border: 1px solid var(--accent);
-    box-shadow: 0 0 10px rgba(0, 255, 153, 0.25);
+    box-shadow: 0 0 10px var(--accent-glow);
 }
 
 .message-bubble {
@@ -55,23 +55,23 @@
 }
 
 .user-bubble {
-    background: #1a1a1e;
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
-    color: #e4e4e7;
+    color: var(--text-main);
     border-top-right-radius: 4px;
-    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
+    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.02);
 }
 
 .ai-bubble {
-    background: rgba(26, 26, 30, 0.6);
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
-    color: #e2e8f0;
+    color: var(--text-main);
     border-top-left-radius: 4px;
-    box-shadow: 0 4px 25px rgba(0, 0, 0, 0.2);
+    box-shadow: 0 4px 25px rgba(0, 0, 0, 0.03);
 }
 
 .paywalled-bubble {
-    border-color: rgba(16, 185, 129, 0.15);
+    border-color: var(--accent-glow);
 }
 
 .message-header {
@@ -109,8 +109,8 @@
 .paywall-teaser {
     position: relative;
     margin-bottom: 1.5rem;
-    -webkit-mask-image: linear-gradient(to bottom, black 30%, transparent 100%);
+    -webkit-mask-image: linear-gradient(to bottom, #000 30%, transparent 100%);
-    mask-image: linear-gradient(to bottom, black 30%, transparent 100%);
+    mask-image: linear-gradient(to bottom, #000 30%, transparent 100%);
     filter: blur(2px);
     pointer-events: none;
     -webkit-user-select: none;
@@ -119,12 +119,12 @@
 
 /* Upsell Card */
 .upsell-card {
-    background: #1a1a1e;
+    background: var(--bg-base);
     border-radius: 12px;
-    border: 1px solid rgba(16, 185, 129, 0.25);
+    border: 1px solid var(--accent-glow);
     padding: 1.5rem;
     margin-top: 1rem;
-    box-shadow: 0 8px 32px rgba(16, 185, 129, 0.08), 0 4px 12px rgba(0, 0, 0, 0.4);
+    box-shadow: 0 8px 32px var(--accent-glow), 0 4px 12px var(--border);
     animation: card-slide-in 0.4s cubic-bezier(0.16, 1, 0.3, 1) forwards;
 }
 
@@ -141,14 +141,14 @@
 
 .upsell-header h4 {
     margin: 0;
-    color: #10b981;
+    color: var(--accent);
     font-size: 1.1rem;
     font-weight: 700;
     letter-spacing: 0.5px;
 }
 
 .upsell-text {
-    color: rgba(255, 255, 255, 0.75);
+    color: var(--text-main);
     font-size: 0.9rem;
     line-height: 1.55;
     margin: 0 0 1.25rem 0;
@@ -177,15 +177,16 @@
 }
 
 .btn-primary {
-    background: #10b981;
+    background: var(--accent);
     border: none;
-    color: #121214;
+    color: var(--bg-surface);
 }
 
 .btn-primary:hover:not(:disabled) {
-    background: #0d9668;
+    background: var(--accent);
+    opacity: 0.9;
     transform: translateY(-2px);
-    box-shadow: 0 4px 15px rgba(16, 185, 129, 0.3);
+    box-shadow: 0 4px 15px var(--accent-glow);
 }
 
 .btn-primary:active:not(:disabled) {
@@ -193,19 +194,19 @@
 }
 
 .btn-primary:disabled {
-    background: rgba(16, 185, 129, 0.5);
+    background: var(--accent-glow);
-    color: rgba(18, 18, 20, 0.6);
+    color: var(--text-muted);
     cursor: not-allowed;
 }
 
 .btn-secondary {
     background: transparent;
-    border: 1px solid #10b981;
+    border: 1px solid var(--accent);
-    color: #10b981;
+    color: var(--accent);
 }
 
 .btn-secondary:hover {
-    background: rgba(16, 185, 129, 0.05);
+    background: var(--accent-glow);
     transform: translateY(-2px);
 }
 
@@ -218,9 +219,9 @@
     display: flex;
     align-items: center;
     gap: 0.75rem;
-    background: rgba(16, 185, 129, 0.1);
+    background: var(--accent-glow);
-    border: 1px solid rgba(16, 185, 129, 0.3);
+    border: 1px solid var(--accent);
-    color: #10b981;
+    color: var(--accent);
     padding: 1rem;
     border-radius: 8px;
     margin-top: 1.25rem;
@@ -238,8 +239,8 @@
 .payment-spinner {
     width: 16px;
     height: 16px;
-    border: 2px solid rgba(18, 18, 20, 0.2);
+    border: 2px solid var(--border);
-    border-top-color: #121214;
+    border-top-color: var(--accent);
     border-radius: 50%;
     margin-right: 0.75rem;
     animation: spin 0.8s linear infinite;
@@ -265,3 +266,49 @@
     0% { transform: rotate(0deg); }
     100% { transform: rotate(360deg); }
 }
+
+/* ============================================================
+   LIGHT THEME OVERRIDES — "Warm Paper / Soft Sepia"
+   ============================================================ */
+
+.theme-light .ai-row .message-avatar {
+    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
+    color: #ffffff;
+    border: 1px solid rgba(16, 185, 129, 0.2);
+    box-shadow: 0 2px 8px rgba(16, 185, 129, 0.15);
+}
+
+.theme-light .user-row .message-avatar {
+    box-shadow: 0 2px 8px rgba(139, 130, 115, 0.1);
+}
+
+.theme-light .upsell-card {
+    box-shadow: 0 8px 32px rgba(16, 185, 129, 0.08), 0 4px 12px rgba(0, 0, 0, 0.04);
+}
+
+.theme-light .btn-primary {
+    background: var(--accent);
+    color: #ffffff;
+}
+
+.theme-light .btn-primary:hover:not(:disabled) {
+    background: #059669;
+    color: #ffffff;
+    opacity: 1;
+    box-shadow: 0 4px 12px rgba(16, 185, 129, 0.15);
+}
+
+.theme-light .btn-secondary {
+    border-color: var(--accent);
+    color: var(--accent);
+}
+
+.theme-light .btn-secondary:hover {
+    background: rgba(16, 185, 129, 0.05);
+}
+
+.theme-light .paywall-teaser {
+    -webkit-mask-image: linear-gradient(to bottom, #000 30%, transparent 100%);
+    mask-image: linear-gradient(to bottom, #000 30%, transparent 100%);
+}
+

src/NexusReader.UI.Shared/Components/Molecules/IntelligenceToolbar.razor

@@ -49,7 +49,7 @@
     protected override void OnInitialized()
     {
         FocusMode.OnFocusModeChanged += HandleUpdate;
-        ThemeService.OnThemeChanged += HandleThemeChangedAsync;
+        ThemeService.OnThemeChanged += HandleThemeChanged;
     }
 
     private async Task HandleClearCache()
@@ -68,11 +68,11 @@
 
     private Task HandleUpdate() => InvokeAsync(StateHasChanged);
 
-    private Task HandleThemeChangedAsync() => InvokeAsync(StateHasChanged);
+    private void HandleThemeChanged(ThemeMode mode) => InvokeAsync(StateHasChanged);
 
     public void Dispose()
     {
         FocusMode.OnFocusModeChanged -= HandleUpdate;
-        ThemeService.OnThemeChanged -= HandleThemeChangedAsync;
+        ThemeService.OnThemeChanged -= HandleThemeChanged;
     }
 }

src/NexusReader.UI.Shared/Components/Organisms/ConceptsMap.razor.css

@@ -233,3 +233,126 @@
 .lock-icon {
     color: rgba(255, 255, 255, 0.2);
 }
+
+/* ============================================================
+   LIGHT THEME OVERRIDES — "Warm Paper / Soft Sepia"
+   ============================================================ */
+
+.theme-light .concepts-map::-webkit-scrollbar-thumb:hover {
+    background: var(--accent);
+}
+
+.theme-light .empty-map-state {
+    background: rgba(0, 0, 0, 0.01);
+    border-color: var(--border);
+    color: var(--text-muted);
+}
+
+.theme-light .empty-map-state .dim-icon {
+    color: var(--text-muted);
+    opacity: 0.4;
+}
+
+.theme-light .timeline-step:hover {
+    background: rgba(0, 0, 0, 0.02);
+}
+
+.theme-light .timeline-step.unlocked:hover {
+    border-color: rgba(16, 185, 129, 0.15);
+    box-shadow: 0 4px 20px rgba(16, 185, 129, 0.05);
+}
+
+.theme-light .timeline-step.selected {
+    background: rgba(16, 185, 129, 0.04);
+    border-color: var(--accent);
+    box-shadow: 0 0 12px rgba(16, 185, 129, 0.15);
+}
+
+.theme-light .node-circle {
+    background: var(--bg-surface);
+}
+
+.theme-light .unlocked .node-circle {
+    background: var(--bg-surface);
+    border-color: var(--accent);
+    color: var(--accent);
+    box-shadow: none;
+}
+
+.theme-light .locked .node-circle {
+    background: var(--bg-base);
+    border-color: var(--border);
+    color: var(--text-muted);
+}
+
+.theme-light .node-glow {
+    display: none;
+}
+
+.theme-light .track-active {
+    background: var(--accent);
+    box-shadow: none;
+}
+
+.theme-light .track-inactive {
+    background: var(--border);
+}
+
+.theme-light .node-content {
+    background: var(--bg-surface);
+    border: 1px solid var(--border);
+}
+
+.theme-light .timeline-step.selected .node-content {
+    background: var(--bg-surface);
+    border-color: rgba(16, 185, 129, 0.2);
+}
+
+.theme-light .segment-tag {
+    color: var(--text-muted);
+}
+
+.theme-light .unlocked .segment-tag {
+    color: var(--accent);
+}
+
+.theme-light .badge-unlocked {
+    background: rgba(16, 185, 129, 0.08);
+    color: var(--accent);
+    border-color: rgba(16, 185, 129, 0.2);
+}
+
+.theme-light .badge-locked {
+    background: var(--bg-base);
+    color: var(--text-muted);
+    border-color: var(--border);
+}
+
+.theme-light .node-title {
+    color: var(--text-main);
+}
+
+.theme-light .timeline-step.unlocked:hover .node-title {
+    color: var(--accent);
+}
+
+.theme-light .locked .node-title {
+    color: var(--text-muted);
+}
+
+.theme-light .node-desc {
+    color: var(--text-muted);
+}
+
+.theme-light .locked .node-desc {
+    color: var(--text-muted);
+}
+
+.theme-light .check-icon {
+    color: var(--accent);
+}
+
+.theme-light .lock-icon {
+    color: var(--text-muted);
+}
+

src/NexusReader.UI.Shared/Components/Organisms/ContextualRecommendationsWidget.razor

@@ -15,7 +15,7 @@
 
     @if (_isLoading)
     {
-        <div class="loading-state" role="status" aria-label="Ładowanie rekomendacji">
+        <div @key='"loading"' class="loading-state" role="status" aria-label="Ładowanie rekomendacji">
             <div class="spinner-ring">
                 <div class="spinner-track"></div>
                 <div class="spinner-head"></div>
@@ -25,24 +25,24 @@
     }
     else if (_hasError)
     {
-        <div class="empty-state">
+        <div @key='"error"' class="empty-state">
             <NexusIcon Name="alert-circle" Size="32" />
             <p>Nie udało się załadować rekomendacji.</p>
         </div>
     }
     else if (_recommendations is null || _recommendations.Count == 0)
     {
-        <div class="empty-state">
+        <div @key='"empty"' class="empty-state">
             <NexusIcon Name="book-open" Size="32" />
             <p>Zacznij czytać, aby odkryć powiązane tytuły.</p>
         </div>
     }
     else
     {
-        <ul class="recommendations-list" role="list">
+        <ul @key='"list"' class="recommendations-list" role="list">
             @foreach (var rec in _recommendations)
             {
-                <li class="recommendation-item @(rec.IsPremiumUpsell ? "premium" : "owned")"
+                <li @key="rec.TargetBookId" class="recommendation-item @(rec.IsPremiumUpsell ? "premium" : "owned")"
                     role="listitem">
                     <div class="rec-content">
                         <div class="rec-meta">

src/NexusReader.UI.Shared/Components/Organisms/ContextualRecommendationsWidget.razor.css

@@ -251,3 +251,80 @@
         padding: 1.25rem;
     }
 }
+
+/* ============================================================
+   LIGHT THEME OVERRIDES — "Warm Paper / Soft Sepia"
+   ============================================================ */
+
+.theme-light .recommendations-panel {
+    background: var(--bg-surface);
+    border: 1px solid var(--border);
+}
+
+.theme-light .recommendations-panel:hover {
+    box-shadow: 0 8px 24px rgba(139, 130, 115, 0.12);
+}
+
+.theme-light .header-left h4 {
+    color: var(--text-main);
+}
+
+.theme-light .spinner-track {
+    border: 3px solid rgba(0, 0, 0, 0.05);
+}
+
+.theme-light .loading-label,
+.theme-light .empty-state {
+    color: var(--text-muted);
+}
+
+.theme-light .recommendation-item {
+    background: rgba(0, 0, 0, 0.02);
+    border: 1px solid rgba(0, 0, 0, 0.06);
+}
+
+.theme-light .recommendation-item:hover {
+    background: rgba(0, 0, 0, 0.04);
+}
+
+.theme-light .recommendation-item.premium {
+    border-color: rgba(245, 158, 11, 0.2);
+}
+
+.theme-light .recommendation-item.premium:hover {
+    border-color: rgba(245, 158, 11, 0.4);
+    background: rgba(245, 158, 11, 0.04);
+}
+
+.theme-light .recommendation-item.owned {
+    border-color: rgba(16, 185, 129, 0.1);
+}
+
+.theme-light .recommendation-item.owned:hover {
+    border-color: rgba(16, 185, 129, 0.25);
+}
+
+.theme-light .rec-book-title {
+    color: var(--text-main);
+}
+
+.theme-light .rec-chapter-title {
+    color: var(--text-muted);
+}
+
+.theme-light .rec-action-btn {
+    border: 1px solid rgba(0, 0, 0, 0.08);
+    color: var(--text-muted);
+}
+
+.theme-light .rec-action-btn:hover {
+    background: rgba(16, 185, 129, 0.1);
+    border-color: rgba(16, 185, 129, 0.3);
+    color: var(--accent);
+}
+
+.theme-light .premium .rec-action-btn:hover {
+    background: rgba(245, 158, 11, 0.1);
+    border-color: rgba(245, 158, 11, 0.3);
+    color: #f59e0b;
+}

src/NexusReader.UI.Shared/Components/Organisms/CurrentReadingWidget.razor

@@ -5,7 +5,7 @@
 <section class="current-reading-card glass-panel">
     @if (Book != null)
     {
-        <div class="card-layout">
+        <div @key='"current-reading-book"' class="card-layout">
             <div class="book-cover">
                 <img src="@(Book.CoverUrl ?? "https://via.placeholder.com/120x180?text=No+Cover")" alt="@Book.Title" />
             </div>
@@ -51,7 +51,7 @@
     }
     else
     {
-        <div class="empty-state">
+        <div @key='"current-reading-empty"' class="empty-state">
             <div class="empty-icon">
                 <NexusIcon Name="book-open" Size="48" />
             </div>

src/NexusReader.UI.Shared/Components/Organisms/CurrentReadingWidget.razor.css

@@ -210,3 +210,60 @@
         align-items: center;
     }
 }
+
+/* ============================================================
+   LIGHT THEME OVERRIDES — "Warm Paper / Soft Sepia"
+   ============================================================ */
+
+.theme-light .current-reading-card {
+    background: var(--bg-surface);
+    border: 1px solid var(--border);
+}
+
+.theme-light .current-reading-card:hover {
+    background: var(--bg-surface);
+    border-color: var(--accent);
+    box-shadow: 0 10px 30px rgba(139, 130, 115, 0.12);
+}
+
+.theme-light .book-cover img {
+    box-shadow: 0 15px 35px rgba(139, 130, 115, 0.18);
+    border: 1px solid rgba(0, 0, 0, 0.06);
+}
+
+.theme-light .book-title {
+    color: var(--text-main);
+}
+
+.theme-light .author-name {
+    color: var(--text-muted);
+}
+
+.theme-light .chapter-name {
+    color: var(--text-main);
+}
+
+.theme-light .progress-bar-container {
+    background: #e4e1d9;
+}
+
+.theme-light .progress-bar-fill {
+    box-shadow: 0 0 6px rgba(16, 185, 129, 0.2);
+}
+
+.theme-light .book-excerpt {
+    color: var(--text-muted);
+}
+
+.theme-light .empty-text h3 {
+    color: var(--text-main);
+}
+
+.theme-light .empty-text p {
+    color: var(--text-muted);
+}
+
+.theme-light .empty-icon {
+    color: var(--accent);
+    filter: none;
+}

src/NexusReader.UI.Shared/Components/Organisms/MobileReaderToolbar.razor

@@ -114,7 +114,7 @@
         ThemeService.OnThemeChanged += HandleThemeChanged;
     }
 
-    private Task HandleThemeChanged() => InvokeAsync(StateHasChanged);
+    private void HandleThemeChanged(ThemeMode mode) => InvokeAsync(StateHasChanged);
 
     private double GetDashOffset()
     {

src/NexusReader.UI.Shared/Components/Organisms/ReaderCanvas.razor

@@ -127,7 +127,7 @@
     protected override async Task OnInitializedAsync()
     {
         await Coordinator.ClearAsync();
-        ThemeService.OnThemeChanged += HandleUpdate;
+        ThemeService.OnThemeChanged += HandleThemeChanged;
         NavigationService.OnNavigationChanged += OnNavigationChanged;
         QuizService.OnQuizUpdated += HandleUpdate;
 
@@ -451,6 +451,8 @@
 
     private Task HandleUpdate() => InvokeAsync(StateHasChanged);
 
+    private void HandleThemeChanged(ThemeMode mode) => InvokeAsync(StateHasChanged);
+
     private void HandleEscape()
     {
         if (ViewModel != null)
@@ -466,7 +468,7 @@
 
     public async ValueTask DisposeAsync()
     {
-        ThemeService.OnThemeChanged -= HandleUpdate;
+        ThemeService.OnThemeChanged -= HandleThemeChanged;
         NavigationService.OnNavigationChanged -= OnNavigationChanged;
         QuizService.OnQuizUpdated -= HandleUpdate;
 

src/NexusReader.UI.Shared/Layout/MainHubLayout.razor

@@ -6,13 +6,13 @@
 
 @if (!_isFullyLoaded)
 {
-    <div class="app-preloader" style="backdrop-filter: blur(15px); background: rgba(18, 18, 18, 0.95); z-index: 100000; color: #ffffff;">
+    <div @key='"preloader"' class="app-preloader" style="backdrop-filter: blur(15px); background: rgba(18, 18, 18, 0.95); z-index: 100000; color: #ffffff;">
         <div class="preloader-spinner"></div>
         <div class="preloader-text" style="color: #ffffff;">Synchronizing Secure Session...</div>
     </div>
 }
 
-<div class="hub-container @(_isMobileMenuOpen ? "mobile-menu-open" : "")">
+<div @key='"hub-container"' class="hub-container @(_isMobileMenuOpen ? "mobile-menu-open" : "")">
     <AuthorizeView>
         <Authorized>
             <!-- Mobile Sticky Top-bar -->

src/NexusReader.UI.Shared/Layout/MainHubLayout.razor.css

@@ -2,16 +2,16 @@
     display: flex;
     width: 100vw;
     height: 100vh;
-    background: #121214;
+    background: var(--bg-base);
-    color: #e4e4e7;
+    color: var(--text-main);
     overflow: hidden;
 }
 
 ::deep .hub-sidebar {
     width: 80px;
     height: 100%;
-    background: #0d0d0d;
+    background: var(--bg-surface);
-    border-right: 1px solid rgba(255, 255, 255, 0.05);
+    border-right: 1px solid var(--border);
     display: flex;
     flex-direction: column;
     z-index: 100;
@@ -55,7 +55,7 @@
     justify-content: center;
     width: 100%;
     height: 54px;
-    color: #8b8273;
+    color: var(--text-muted);
     text-decoration: none;
     transition: color 0.2s ease, background-color 0.2s ease;
     position: relative;
@@ -63,7 +63,7 @@
 
 ::deep .nav-item:hover {
     color: #10b981;
-    background: rgba(255, 255, 255, 0.01);
+    background: rgba(0, 0, 0, 0.04);
 }
 
 ::deep .nav-item:focus-visible {
@@ -103,7 +103,7 @@
 
 ::deep .sidebar-footer {
     padding: 1.5rem 0;
-    border-top: 1px solid rgba(255, 255, 255, 0.05);
+    border-top: 1px solid var(--border);
     display: flex;
     flex-direction: column;
     align-items: center;
@@ -119,15 +119,15 @@
 ::deep .user-avatar {
     width: 36px;
     height: 36px;
-    background: #1a1a1e;
+    background: var(--bg-base);
-    border: 1px solid rgba(255, 255, 255, 0.08);
+    border: 1px solid var(--border);
     border-radius: 50%;
     display: flex;
     align-items: center;
     justify-content: center;
     font-size: 0.9rem;
     font-weight: 600;
-    color: #e4e4e7;
+    color: var(--text-main);
     flex-shrink: 0;
 }
 
@@ -138,7 +138,7 @@
 ::deep .logout-btn {
     background: transparent;
     border: none;
-    color: #8b8273;
+    color: var(--text-muted);
     cursor: pointer;
     padding: 0.5rem;
     border-radius: 8px;
@@ -157,7 +157,7 @@
     flex: 1;
     height: 100%;
     overflow-y: auto;
-    background: #121214;
+    background: var(--bg-base);
 }
 
 .hub-content {
@@ -204,10 +204,10 @@
         left: 0;
         right: 0;
         height: 60px;
-        background: rgba(18, 18, 18, 0.85);
+        background: var(--bg-surface);
         backdrop-filter: blur(20px);
         -webkit-backdrop-filter: blur(20px);
-        border-bottom: 1px solid rgba(255, 255, 255, 0.05);
+        border-bottom: 1px solid var(--border);
         padding: 0 1.25rem;
         z-index: 150;
     }
@@ -295,7 +295,7 @@
         bottom: 0;
         width: 280px;
         height: 100%;
-        background: #141414;
+        background: var(--bg-surface);
         z-index: 200;
         transform: translateX(-100%);
         will-change: transform;
@@ -324,7 +324,7 @@
 
     ::deep .sidebar-header {
         padding: 1.5rem 1.25rem;
-        border-bottom: 1px solid rgba(255, 255, 255, 0.05);
+        border-bottom: 1px solid var(--border);
     }
 
     ::deep .sidebar-nav {
@@ -342,4 +342,80 @@
     }
 }
 
+/* ============================================================
+   LIGHT THEME OVERRIDES — "Warm Paper / Soft Sepia"
+   Scoped via .theme-light on an ancestor element.
+   ============================================================ */
 
+/* --- Desktop Sidebar: warm paper shadow --- */
+.theme-light ::deep .hub-sidebar {
+    box-shadow: 4px 0 20px rgba(139, 130, 115, 0.08);
+}
+
+/* --- Logo icon: remove neon glow --- */
+.theme-light ::deep .logo-icon {
+    filter: none;
+}
+
+/* --- Nav item hover: ensure green text, warm hover bg --- */
+.theme-light ::deep .nav-item:hover {
+    color: #10b981;
+    background: rgba(0, 0, 0, 0.02);
+}
+
+/* --- Nav active indicator: reduced glow --- */
+.theme-light ::deep .nav-item.active::before {
+    box-shadow: 0 0 8px rgba(16, 185, 129, 0.3);
+}
+
+/* --- Nexus loader: remove neon drop-shadow --- */
+.theme-light ::deep .nexus-loader {
+    filter: none;
+}
+
+/* --- Mobile Styles --- */
+@media (max-width: 768px) {
+
+    /* Hamburger button: dark text on warm paper */
+    .theme-light .hamburger-btn {
+        color: #292524;
+    }
+
+    .theme-light .hamburger-btn:hover {
+        background: rgba(0, 0, 0, 0.04);
+    }
+
+    /* User avatar mini: solid accent, white text, no neon glow */
+    .theme-light .user-avatar-mini {
+        background: #10b981;
+        border: 1px solid rgba(0, 0, 0, 0.08);
+        color: #ffffff;
+        box-shadow: 0 2px 8px rgba(16, 185, 129, 0.15);
+    }
+
+    /* Pulsing logo: subtle accent pulse, no neon glow */
+    .theme-light .pulsing-logo {
+        animation: pulse-glow-light 2s infinite ease-in-out;
+    }
+
+    @keyframes pulse-glow-light {
+        0%, 100% {
+            filter: none;
+            opacity: 0.85;
+        }
+        50% {
+            filter: drop-shadow(0 0 4px rgba(16, 185, 129, 0.2));
+            opacity: 1;
+        }
+    }
+
+    /* Mobile sidebar open state: warm shadow instead of dark */
+    .theme-light .mobile-menu-open ::deep .hub-sidebar {
+        box-shadow: 10px 0 30px rgba(139, 130, 115, 0.2);
+    }
+
+    /* Mobile topbar: warm paper border */
+    .theme-light .nexus-mobile-topbar {
+        border-bottom-color: rgba(0, 0, 0, 0.08);
+    }
+}

src/NexusReader.UI.Shared/Layout/ReaderLayout.razor

@@ -343,7 +343,7 @@
         InteractionService.OnAssistantRequested += HandleAssistantRequestedAsync;
         InteractionService.OnScrollPercentChanged += HandleScrollPercentChanged;
         GraphService.OnGraphUpdated += HandleGraphUpdatedAsync;
-        ThemeService.OnThemeChanged += HandleThemeChangedAsync;
+        ThemeService.OnThemeChanged += HandleThemeChanged;
         Coordinator.OnSelectionSummaryStateChanged += HandleUpdate;
 
         var context = PlatformService.GetDeviceContext();
@@ -359,7 +359,7 @@
         }
     }
 
-    private async Task HandleThemeChangedAsync() => await InvokeAsync(StateHasChanged);
+    private void HandleThemeChanged(ThemeMode mode) => InvokeAsync(StateHasChanged);
 
     private void SetActiveTab(SidebarTab tab)
     {
@@ -520,7 +520,7 @@
         InteractionService.OnAssistantRequested -= HandleAssistantRequestedAsync;
         InteractionService.OnScrollPercentChanged -= HandleScrollPercentChanged;
         GraphService.OnGraphUpdated -= HandleGraphUpdatedAsync;
-        ThemeService.OnThemeChanged -= HandleThemeChangedAsync;
+        ThemeService.OnThemeChanged -= HandleThemeChanged;
         Coordinator.OnSelectionSummaryStateChanged -= HandleUpdate;
 
         try

src/NexusReader.UI.Shared/Pages/Account/Login.razor

@@ -33,7 +33,7 @@
             <span>lub</span>
         </div>
 
-        <EditForm Model="@_loginModel" OnValidSubmit="HandleLogin" class="auth-form">
+        <EditForm FormName="login-form" Model="@_loginModel" OnValidSubmit="HandleLogin" class="auth-form">
             <DataAnnotationsValidator />
 
             <div class="field-group">
@@ -98,7 +98,7 @@
     </div>
 </div>
 
-<form id="nexusLoginForm" method="post" action="/account/login-form" style="display:none">
+<form @formname="hidden-login-form" id="nexusLoginForm" method="post" action="/account/login-form" style="display:none">
     <input type="hidden" name="email" value="@_loginModel.Email" />
     <input type="hidden" name="password" value="@_loginModel.Password" />
     <input type="hidden" name="rememberMe" value="@(_loginModel.RememberMe ? "true" : "false")" />
@@ -117,7 +117,10 @@
     [SupplyParameterFromQuery(Name = "returnUrl")]
     public string? ReturnUrl { get; set; }
 
-    private LoginModel _loginModel = new();
+#pragma warning disable BL0008
+    [SupplyParameterFromForm(FormName = "login-form")]
+    private LoginModel _loginModel { get; set; } = new();
+#pragma warning restore BL0008
     private string? _errorMessage;
     private bool _isSubmitting;
     private bool _showPassword;

src/NexusReader.UI.Shared/Pages/Account/Profile.razor

@@ -4,8 +4,10 @@
 @using NexusReader.UI.Shared.Services
 @using NexusReader.UI.Shared.Components.Atoms
 @attribute [Authorize]
+@using NexusReader.Domain.Enums
 @inject IIdentityService IdentityService
 @inject NavigationManager NavigationManager
+@inject IThemeService ThemeService
 
 <div class="profile-page-container">
     <div class="background-radial"></div>
@@ -97,6 +99,31 @@
                         </div>
                     </div>
                 </div>
+
+                <!-- Theme Preferences Card -->
+                <div class="metric-card glass-panel full-width theme-preference-card">
+                    <div class="card-header">
+                        <NexusIcon Name="settings" Size="24" Color="#10b981" />
+                        <h3>Preferencje Wizualne</h3>
+                    </div>
+                    <div class="card-body theme-selector-layout">
+                        <p class="theme-description">Wybierz profil wizualny systemu zoptymalizowany dla Twojego urządzenia i warunków czytania.</p>
+                        <div class="theme-options">
+                            <button class="theme-option-btn @(ThemeService.Mode == ThemeMode.System ? "active" : "")" @onclick="() => ChangeTheme(ThemeMode.System)">
+                                <NexusIcon Name="cpu" Size="16" />
+                                <span>Systemowy</span>
+                            </button>
+                            <button class="theme-option-btn @(ThemeService.Mode == ThemeMode.Dark ? "active" : "")" @onclick="() => ChangeTheme(ThemeMode.Dark)">
+                                <NexusIcon Name="moon" Size="16" />
+                                <span>Modern Deep Dark</span>
+                            </button>
+                            <button class="theme-option-btn @(ThemeService.Mode == ThemeMode.LightSepia ? "active" : "")" @onclick="() => ChangeTheme(ThemeMode.LightSepia)">
+                                <NexusIcon Name="sun" Size="16" />
+                                <span>Warm Sepia</span>
+                            </button>
+                        </div>
+                    </div>
+                </div>
             </div>
         </div>
     }
@@ -110,6 +137,7 @@
 
     protected override async Task OnInitializedAsync()
     {
+        await ThemeService.InitializeAsync();
         var result = await IdentityService.GetProfileAsync();
         if (result.IsSuccess) 
         {
@@ -118,6 +146,12 @@
         StateHasChanged();
     }
 
+    private async Task ChangeTheme(ThemeMode mode)
+    {
+        await ThemeService.SetThemeAsync(mode);
+        StateHasChanged();
+    }
+
     private int CalculateProgress()
     {
         if (_profile == null || _profile.AITokenLimit == 0) return 0;

src/NexusReader.UI.Shared/Pages/Account/Profile.razor.css

@@ -2,8 +2,8 @@
     position: relative;
     width: 100%;
     min-height: 100vh;
-    background-color: #121214;
+    background-color: var(--bg-base);
-    color: #e4e4e7;
+    color: var(--text-main);
     overflow-x: hidden;
     display: flex;
     justify-content: center;
@@ -26,7 +26,7 @@
 .mesh-overlay {
     position: absolute;
     top: 0; left: 0; width: 100%; height: 100%;
-    background-image: radial-gradient(circle at 1px 1px, rgba(255, 255, 255, 0.02) 1px, transparent 0);
+    background-image: radial-gradient(circle at 1px 1px, var(--border) 1px, transparent 0);
     background-size: 32px 32px;
     z-index: 1;
 }
@@ -63,7 +63,7 @@
 .avatar-inner {
     width: 120px;
     height: 120px;
-    background: #1a1a1e;
+    background: var(--bg-surface);
     border: 2px solid #10b981;
     border-radius: 50%;
     display: flex;
@@ -98,7 +98,7 @@
     font-weight: 700;
     margin: 0;
     letter-spacing: -0.01em;
-    color: #ffffff;
+    color: var(--text-main);
 }
 
 .system-rank {
@@ -120,17 +120,17 @@
 
 .glass-panel {
     padding: 32px;
-    background: #1a1a1e;
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
     border-radius: 12px;
     transition: all 0.3s ease;
 }
 
 .glass-panel:hover {
-    border-color: rgba(16, 185, 129, 0.2);
+    border-color: var(--accent);
     transform: translateY(-4px);
-    background: #1e1e24;
+    background: var(--bg-surface);
-    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
+    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
 }
 
 .metric-card {
@@ -154,7 +154,7 @@
     font-weight: 600;
     text-transform: uppercase;
     letter-spacing: 0.1em;
-    color: #a0aec0;
+    color: var(--text-muted);
     margin: 0;
 }
 
@@ -177,14 +177,14 @@
     gap: 8px;
 }
 
-.usage-values .current { font-size: 2.5rem; font-weight: 800; color: #fff; line-height: 1; }
+.usage-values .current { font-size: 2.5rem; font-weight: 800; color: var(--text-main); line-height: 1; }
-.usage-values .separator { font-size: 1.2rem; color: #4a5568; }
+.usage-values .separator { font-size: 1.2rem; color: var(--border); }
-.usage-values .total { font-size: 1.2rem; color: #718096; font-weight: 600; }
+.usage-values .total { font-size: 1.2rem; color: var(--text-muted); font-weight: 600; }
 
 .usage-progress {
     width: 100%;
     height: 6px;
-    background: rgba(255, 255, 255, 0.05);
+    background: var(--border);
     border-radius: 10px;
     overflow: hidden;
 }
@@ -198,7 +198,7 @@
 
 .metric-label {
     font-size: 0.75rem;
-    color: #718096;
+    color: var(--text-muted);
     text-transform: uppercase;
     letter-spacing: 0.05em;
 }
@@ -218,7 +218,7 @@
 
 .score-label {
     font-size: 0.75rem;
-    color: #718096;
+    color: var(--text-muted);
     text-transform: uppercase;
     margin-top: 4px;
 }
@@ -229,11 +229,11 @@
     align-items: center;
     gap: 8px;
     padding: 10px 16px;
-    background: rgba(16, 185, 129, 0.05);
+    background: var(--bg-base);
-    border: 1px solid rgba(16, 185, 129, 0.1);
+    border: 1px solid var(--border);
     border-radius: 12px;
     font-size: 0.85rem;
-    color: #cbd5e0;
+    color: var(--text-main);
 }
 
 .truncate {
@@ -273,9 +273,9 @@
 }
 
 .plan-badge.free {
-    background: rgba(255, 255, 255, 0.05);
+    background: var(--bg-base);
-    color: #a1a1aa;
+    color: var(--text-muted);
-    border: 1px solid rgba(255, 255, 255, 0.1);
+    border: 1px solid var(--border);
 }
 
 .tenant-tag {
@@ -348,3 +348,111 @@
     .btn-nexus { width: 100%; justify-content: center; }
     .username { font-size: 2.2rem; }
 }
+
+/* Theme Preference Card Styles */
+.theme-preference-card {
+    margin-top: 12px;
+}
+
+.theme-description {
+    font-size: 0.9rem;
+    color: var(--text-muted);
+    margin: 0 0 16px 0;
+}
+
+.theme-options {
+    display: flex;
+    gap: 16px;
+    width: 100%;
+}
+
+.theme-option-btn {
+    flex: 1;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    gap: 8px;
+    padding: 14px 20px;
+    background: var(--bg-base);
+    border: 1px solid var(--border);
+    border-radius: 8px;
+    color: var(--text-muted);
+    font-size: 0.9rem;
+    font-weight: 600;
+    cursor: pointer;
+    transition: all 0.2s ease;
+}
+
+.theme-option-btn:hover {
+    background: rgba(0, 0, 0, 0.04);
+    color: var(--text-main);
+}
+
+.theme-option-btn.active {
+    background: rgba(16, 185, 129, 0.1);
+    color: #10b981;
+    border-color: #10b981;
+    box-shadow: 0 0 15px rgba(16, 185, 129, 0.15);
+}
+
+@media (max-width: 768px) {
+    .theme-options {
+        flex-direction: column;
+    }
+}
+
+/* ============================================
+   Light Theme Overrides — Warm Paper / Soft Sepia
+   ============================================ */
+
+/* Background radial — warmer, slightly stronger glow */
+.theme-light .background-radial {
+    background: radial-gradient(circle, rgba(16, 185, 129, 0.04) 0%, transparent 70%);
+}
+
+/* Avatar — keep green accent, reduce glow intensity */
+.theme-light .avatar-inner {
+    box-shadow: 0 0 20px rgba(16, 185, 129, 0.12), inset 0 0 15px rgba(16, 185, 129, 0.05);
+}
+
+/* Avatar glow ring — softer border */
+.theme-light .avatar-glow {
+    border-color: rgba(16, 185, 129, 0.2);
+}
+
+/* Glass panel hover — warm sepia shadow instead of pure black */
+.theme-light .glass-panel:hover {
+    box-shadow: 0 10px 30px rgba(139, 130, 115, 0.12);
+}
+
+/* Progress bar — reduce neon glow */
+.theme-light .progress-bar {
+    box-shadow: 0 0 10px rgba(16, 185, 129, 0.2);
+}
+
+/* Decorative text — dark ink on light bg instead of light on dark */
+.theme-light .decoration {
+    color: rgba(0, 0, 0, 0.04);
+}
+
+/* Tenant tag — warm stone gray */
+.theme-light .tenant-tag {
+    color: #78716c;
+}
+
+/* Loader — disable neon drop-shadow, softer border */
+.theme-light .nexus-loader {
+    border-color: rgba(16, 185, 129, 0.15);
+    border-top-color: #10b981;
+    filter: none;
+}
+
+/* Theme option active — reduce glow in light mode */
+.theme-light .theme-option-btn.active {
+    box-shadow: 0 0 10px rgba(16, 185, 129, 0.1);
+}
+
+/* Progress bar track — light stone gray */
+.theme-light .usage-progress {
+    background: #e4e1d9;
+}

src/NexusReader.UI.Shared/Pages/Account/Register.razor

@@ -21,7 +21,7 @@
             <p class="auth-subtitle">Utwórz nowe konto</p>
         </div>
 
-        <EditForm Model="@_registerModel" OnValidSubmit="HandleRegister" class="auth-form">
+        <EditForm FormName="register-form" Model="@_registerModel" OnValidSubmit="HandleRegister" class="auth-form">
             <DataAnnotationsValidator />
 
             <div class="field-group">
@@ -71,14 +71,17 @@
     </div>
 </div>
 
-<form id="nexusLoginForm" method="post" action="/account/login-form" style="display:none">
+<form @formname="hidden-register-login-form" id="nexusLoginForm" method="post" action="/account/login-form" style="display:none">
     <input type="hidden" name="email" value="@_registerModel.Email" />
     <input type="hidden" name="password" value="@_registerModel.Password" />
     <input type="hidden" name="rememberMe" value="false" />
 </form>
 
 @code {
-    private RegisterModel _registerModel = new();
+#pragma warning disable BL0008
+    [SupplyParameterFromForm(FormName = "register-form")]
+    private RegisterModel _registerModel { get; set; } = new();
+#pragma warning restore BL0008
     private string? _errorMessage;
     private bool _isSubmitting;
 

src/NexusReader.UI.Shared/Pages/Catalog.razor.css

@@ -14,13 +14,13 @@
     font-size: 2.5rem;
     font-weight: 700;
     margin: 0 0 0.5rem 0;
-    color: #ffffff;
+    color: var(--text-main);
     letter-spacing: -0.5px;
 }
 
 .catalog-header .subtitle {
     font-size: 1rem;
-    color: #a1a1aa;
+    color: var(--text-muted);
     margin: 0;
 }
 
@@ -38,27 +38,27 @@
     height: 100%;
     overflow: hidden;
     border-radius: 12px;
-    background: #1a1a1e;
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
     transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
     position: relative;
 }
 
 .course-card:hover {
     transform: translateY(-4px);
-    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.3);
+    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.1);
-    border-color: rgba(16, 185, 129, 0.2);
+    border-color: var(--accent);
 }
 
 .card-cover-container {
     position: relative;
     height: 200px;
-    background: rgba(0, 0, 0, 0.2);
+    background: rgba(0, 0, 0, 0.05);
     overflow: hidden;
     display: flex;
     align-items: center;
     justify-content: center;
-    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
+    border-bottom: 1px solid var(--border);
 }
 
 .card-cover {
@@ -147,8 +147,9 @@
     align-self: flex-start;
     font-size: 0.7rem;
     font-weight: 700;
-    color: #a1a1aa;
+    color: var(--text-muted);
-    background: rgba(255, 255, 255, 0.05);
+    background: var(--bg-base);
+    border: 1px solid var(--border);
     padding: 0.2rem 0.5rem;
     border-radius: 4px;
     text-transform: uppercase;
@@ -175,21 +176,21 @@
     font-size: 1.25rem;
     font-weight: 600;
     margin: 0 0 0.4rem 0;
-    color: #ffffff;
+    color: var(--text-main);
     line-height: 1.3;
     font-family: var(--nexus-font-sans, "Outfit", sans-serif);
 }
 
 .course-author {
     font-size: 0.85rem;
-    color: #a1a1aa;
+    color: var(--text-muted);
     margin: 0 0 1rem 0;
 }
 
 .course-desc {
     font-size: 0.88rem;
     line-height: 1.5;
-    color: #a1a1aa;
+    color: var(--text-muted);
     margin: 0 0 1.5rem 0;
     display: -webkit-box;
     -webkit-line-clamp: 3;
@@ -204,8 +205,8 @@
     justify-content: space-between;
     align-items: center;
     font-size: 0.8rem;
-    color: #a1a1aa;
+    color: var(--text-muted);
-    border-top: 1px solid rgba(255, 255, 255, 0.05);
+    border-top: 1px solid var(--border);
     padding-top: 0.75rem;
 }
 
@@ -256,14 +257,14 @@
     border-radius: 12px;
     overflow: hidden;
     height: 440px;
-    background: #1a1a1e;
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
     opacity: 0.6;
 }
 
 .skeleton-cover {
     height: 200px;
-    background: linear-gradient(90deg, rgba(255,255,255,0.02) 25%, rgba(255,255,255,0.06) 50%, rgba(255,255,255,0.02) 75%);
+    background: linear-gradient(90deg, var(--bg-base) 25%, var(--border) 50%, var(--bg-base) 75%);
     background-size: 200% 100%;
     animation: loading 1.5s infinite;
 }
@@ -276,7 +277,7 @@
 }
 
 .skeleton-line {
-    background: linear-gradient(90deg, rgba(255,255,255,0.02) 25%, rgba(255,255,255,0.06) 50%, rgba(255,255,255,0.02) 75%);
+    background: linear-gradient(90deg, var(--bg-base) 25%, var(--border) 50%, var(--bg-base) 75%);
     background-size: 200% 100%;
     animation: loading 1.5s infinite;
     border-radius: 4px;
@@ -314,9 +315,9 @@
     gap: 1.25rem;
     padding: 1.25rem 2.25rem;
     border-radius: 40px;
-    background: rgba(13, 13, 15, 0.85);
+    background: var(--bg-surface);
     backdrop-filter: blur(16px);
-    border: 1px solid rgba(255, 255, 255, 0.08);
+    border: 1px solid var(--border);
     animation: scaleIn 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
 }
 
@@ -332,7 +333,7 @@
 
 .loader-text {
     font-weight: 500;
-    color: #ffffff;
+    color: var(--text-main);
     font-size: 0.95rem;
 }
 
@@ -356,3 +357,34 @@
     from { transform: translate(-50%, -50%) scale(0.9); opacity: 0; }
     to { transform: translate(-50%, -50%) scale(1); opacity: 1; }
 }
+
+/* ============================================
+   LIGHT THEME OVERRIDES — Warm Paper / Soft Sepia
+   ============================================ */
+
+.theme-light .course-card:hover {
+    box-shadow: 0 12px 30px rgba(139, 130, 115, 0.15);
+}
+
+.theme-light .card-cover-container {
+    background: rgba(0, 0, 0, 0.03);
+}
+
+.theme-light .cover-overlay {
+    background: rgba(0, 0, 0, 0.5);
+}
+
+.theme-light .course-card:hover .start-action {
+    color: #292524;
+}
+
+.theme-light .dotnet-gradient,
+.theme-light .blazor-gradient,
+.theme-light .graph-gradient {
+    background: #e4e1d9;
+}
+
+.theme-light .cover-code-text {
+    color: var(--text-main);
+    text-shadow: none;
+}

src/NexusReader.UI.Shared/Pages/ConceptsDashboard.razor.css

@@ -17,11 +17,11 @@
     align-items: center;
     gap: 2rem;
     padding: 1.25rem 2rem;
-    background: rgba(20, 20, 20, 0.35);
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
     border-radius: 16px;
     backdrop-filter: blur(12px);
-    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.2);
+    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.05);
 }
 
 .header-back .btn-back {
@@ -30,22 +30,22 @@
 }
 
 .header-back .btn-back:hover {
-    border-color: var(--nexus-neon);
+    border-color: var(--accent);
-    color: var(--nexus-neon);
+    color: var(--accent);
-    background: var(--nexus-primary-glow);
+    background: var(--accent-glow);
-    box-shadow: 0 0 10px var(--nexus-primary-glow);
+    box-shadow: 0 0 10px var(--accent-glow);
 }
 
 .header-title h1 {
     margin: 0;
     font-size: 1.5rem;
     font-weight: 700;
-    color: #fff;
+    color: var(--text-main);
 }
 
 .header-title .subtitle {
     font-size: 0.85rem;
-    color: rgba(255, 255, 255, 0.4);
+    color: var(--text-muted);
 }
 
 .header-actions .btn-action {
@@ -56,7 +56,7 @@
 }
 
 .header-actions .btn-action:hover {
-    box-shadow: 0 0 20px var(--nexus-primary-glow);
+    box-shadow: 0 0 20px var(--accent-glow);
 }
 
 /* Grid Layout */
@@ -73,28 +73,26 @@
     flex-direction: column;
     overflow: hidden;
     padding: 0;
+    background: var(--bg-surface);
+    border: 1px solid var(--border);
+    border-radius: var(--radius-xl, 16px);
 }
 
 .pane-header {
     padding: 1.25rem 1.5rem;
-    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
+    border-bottom: 1px solid var(--border);
 }
 
 .pane-header h3 {
     margin: 0;
     font-size: 1rem;
     font-weight: 600;
-    color: #fff;
+    color: var(--text-main);
     display: flex;
     align-items: center;
     gap: 0.5rem;
 }
 
-.pane-content {
-    flex-grow: 1;
-    overflow: hidden;
-}
-
 /* Loading, Error and Empty States */
 .loading-state, .error-state, .empty-dashboard-state {
     display: flex;
@@ -118,15 +116,15 @@
 }
 
 .neon-pulse {
-    color: var(--nexus-neon);
+    color: var(--accent);
-    filter: drop-shadow(0 0 10px var(--nexus-neon));
+    filter: drop-shadow(0 0 10px var(--accent-glow));
     animation: robot-pulse 2s infinite ease-in-out;
 }
 
 @keyframes robot-pulse {
-    0% { transform: scale(1); filter: drop-shadow(0 0 10px var(--nexus-neon)); }
+    0% { transform: scale(1); filter: drop-shadow(0 0 10px var(--accent-glow)); }
-    50% { transform: scale(1.08); filter: drop-shadow(0 0 25px var(--nexus-neon)); }
+    50% { transform: scale(1.08); filter: drop-shadow(0 0 25px var(--accent-glow)); }
-    100% { transform: scale(1); filter: drop-shadow(0 0 10px var(--nexus-neon)); }
+    100% { transform: scale(1); filter: drop-shadow(0 0 10px var(--accent-glow)); }
 }
 
 .scan-line {
@@ -135,8 +133,8 @@
     left: 0;
     width: 100%;
     height: 2px;
-    background: var(--nexus-neon);
+    background: var(--accent);
-    box-shadow: 0 0 15px var(--nexus-neon);
+    box-shadow: 0 0 15px var(--accent);
     animation: scan 2s infinite linear;
     opacity: 0.8;
 }
@@ -149,7 +147,7 @@
 
 .loading-text {
     font-size: 0.95rem;
-    color: rgba(255, 255, 255, 0.7);
+    color: var(--text-muted);
     margin-top: 1rem;
     letter-spacing: 0.05em;
 }
@@ -164,17 +162,18 @@
 }
 
 .dim-icon {
-    color: rgba(255, 255, 255, 0.15);
+    color: var(--text-muted);
+    opacity: 0.4;
 }
 
 .empty-dashboard-state h2, .error-state h3 {
-    color: #fff;
+    color: var(--text-main);
     margin: 0 0 0.75rem 0;
     font-weight: 600;
 }
 
 .empty-dashboard-state p, .error-state p {
-    color: rgba(255, 255, 255, 0.45);
+    color: var(--text-muted);
     font-size: 0.88rem;
     line-height: 1.5;
     margin: 0 0 2rem 0;
@@ -189,25 +188,25 @@
     flex-grow: 1;
     padding: 3rem;
     text-align: center;
-    color: rgba(255, 255, 255, 0.4);
+    color: var(--text-muted);
 }
 
 .empty-glowing-brain {
     width: 80px;
     height: 80px;
     border-radius: 50%;
-    background: rgba(0, 255, 153, 0.04);
+    background: var(--accent-glow);
-    border: 1px solid rgba(0, 255, 153, 0.15);
+    border: 1px solid var(--accent);
     display: flex;
     align-items: center;
     justify-content: center;
     margin-bottom: 1.5rem;
-    box-shadow: 0 0 20px var(--nexus-primary-glow);
+    box-shadow: 0 0 20px var(--accent-glow);
 }
 
 .workspace-empty h4 {
     margin: 0 0 0.75rem 0;
-    color: #fff;
+    color: var(--text-main);
     font-size: 1.1rem;
     font-weight: 600;
 }
@@ -227,7 +226,7 @@
 
 .workspace-header {
     padding: 1.5rem;
-    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
+    border-bottom: 1px solid var(--border);
 }
 
 .node-meta {
@@ -242,7 +241,7 @@
     font-size: 0.75rem;
     font-weight: 700;
     letter-spacing: 0.08em;
-    color: var(--nexus-neon);
+    color: var(--accent);
 }
 
 .badge {
@@ -256,22 +255,22 @@
 }
 
 .badge-unlocked {
-    background: rgba(0, 255, 153, 0.08);
+    background: var(--accent-glow);
-    color: var(--nexus-neon);
+    color: var(--accent);
-    border: 1px solid rgba(0, 255, 153, 0.2);
+    border: 1px solid var(--accent);
 }
 
 .badge-locked {
-    background: rgba(255, 255, 255, 0.05);
+    background: var(--bg-base);
-    color: rgba(255, 255, 255, 0.4);
+    color: var(--text-muted);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
 }
 
 .workspace-title {
     margin: 0;
     font-size: 1.4rem;
     font-weight: 700;
-    color: #fff;
+    color: var(--text-main);
 }
 
 .workspace-body {
@@ -291,22 +290,22 @@
     background: transparent;
 }
 .workspace-body::-webkit-scrollbar-thumb {
-    background: rgba(255, 255, 255, 0.08);
+    background: var(--border);
     border-radius: 3px;
 }
 .workspace-body::-webkit-scrollbar-thumb:hover {
-    background: var(--nexus-neon);
+    background: var(--accent);
 }
 
 .locked-warning {
     display: flex;
     flex-direction: row;
     gap: 1rem;
-    background: rgba(255, 171, 0, 0.04);
+    background: rgba(217, 119, 6, 0.05);
-    border: 1px solid rgba(255, 171, 0, 0.15);
+    border: 1px solid rgba(217, 119, 6, 0.15);
     border-radius: 8px;
     padding: 1rem;
-    color: rgba(255, 255, 255, 0.85);
+    color: var(--text-main);
 }
 
 .lock-warning-icon {
@@ -326,14 +325,14 @@
     margin: 0;
     font-size: 0.8rem;
     line-height: 1.4;
-    color: rgba(255, 255, 255, 0.55);
+    color: var(--text-muted);
 }
 
 .metadata-section h4 {
     margin: 0 0 0.5rem 0;
     font-size: 0.85rem;
     font-weight: 600;
-    color: #aaa;
+    color: var(--text-muted);
     display: flex;
     align-items: center;
     gap: 0.35rem;
@@ -345,12 +344,12 @@
     margin: 0;
     font-size: 0.88rem;
     line-height: 1.6;
-    color: rgba(255, 255, 255, 0.7);
+    color: var(--text-main);
 }
 
 .summary-box {
-    background: rgba(255, 255, 255, 0.02);
+    background: var(--bg-base);
-    border-left: 3px solid var(--nexus-neon);
+    border-left: 3px solid var(--accent);
     border-radius: 0 8px 8px 0;
     padding: 1rem;
     margin-top: 0.25rem;
@@ -365,9 +364,9 @@
 
 .term-pill {
     font-size: 0.75rem;
-    background: rgba(255, 255, 255, 0.03);
+    background: var(--bg-base);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
-    color: rgba(255, 255, 255, 0.6);
+    color: var(--text-muted);
     padding: 0.3rem 0.75rem;
     border-radius: 20px;
     font-weight: 500;
@@ -375,14 +374,14 @@
 }
 
 .term-pill:hover {
-    border-color: rgba(0, 255, 153, 0.2);
+    border-color: var(--accent);
-    color: var(--nexus-neon);
+    color: var(--accent);
-    background: rgba(0, 255, 153, 0.03);
+    background: var(--accent-glow);
 }
 
 .workspace-footer {
     padding: 1.25rem 1.5rem;
-    border-top: 1px solid rgba(255, 255, 255, 0.05);
+    border-top: 1px solid var(--border);
 }
 
 @media (max-width: 1024px) {
@@ -403,3 +402,54 @@
         justify-content: center;
     }
 }
+
+/* ============================================
+   Light Theme Overrides — Warm Paper / Soft Sepia
+   ============================================ */
+
+/* Dashboard header — warm sepia shadow instead of pure black */
+.theme-light .dashboard-header {
+    box-shadow: 0 4px 30px rgba(139, 130, 115, 0.05);
+}
+
+/* Neon pulse icon — disable glow filter entirely */
+.theme-light .neon-pulse {
+    filter: none;
+}
+
+/* Override the neon pulse keyframe states in light mode */
+.theme-light .neon-pulse {
+    animation-name: robot-pulse-light;
+}
+
+@keyframes robot-pulse-light {
+    0% { transform: scale(1); filter: none; }
+    50% { transform: scale(1.08); filter: none; }
+    100% { transform: scale(1); filter: none; }
+}
+
+/* Scan line — reduce glow intensity */
+.theme-light .scan-line {
+    box-shadow: 0 0 8px rgba(16, 185, 129, 0.3);
+    opacity: 0.5;
+}
+
+/* Glowing brain empty state — subtle warm glow */
+.theme-light .empty-glowing-brain {
+    box-shadow: 0 0 12px rgba(16, 185, 129, 0.1);
+}
+
+/* Error icon — reduce drop-shadow intensity */
+.theme-light .error-icon {
+    filter: drop-shadow(0 0 4px rgba(255, 74, 74, 0.2));
+}
+
+/* Back button hover — warm glow instead of neon */
+.theme-light .header-back .btn-back:hover {
+    box-shadow: 0 0 8px rgba(16, 185, 129, 0.1);
+}
+
+/* Action button hover — warm glow */
+.theme-light .header-actions .btn-action:hover {
+    box-shadow: 0 0 12px rgba(16, 185, 129, 0.1);
+}

src/NexusReader.UI.Shared/Pages/Dashboard.razor

@@ -61,24 +61,28 @@
                         
                         @if (_profile?.MappedConcepts != null && _profile.MappedConcepts.Any())
                         {
+                            <div @key='"satellite-concepts-container"' style="display: contents;">
                                 @for (int i = 0; i < _profile.MappedConcepts.Count; i++)
                                 {
                                     var concept = _profile.MappedConcepts[i];
                                     var angle = i * (360.0 / _profile.MappedConcepts.Count);
                                     var dist = 65;
-                                <div class="graph-node satellite" 
+                                    <div @key="concept.Id" class="graph-node satellite" 
                                          style="--angle: @(angle)deg; --dist: @(dist)px;"
                                          title="[@concept.Type] @concept.Content"
                                          @onmouseover="() => SetHoveredConcept(concept)"
                                          @onmouseout="ClearHoveredConcept">
                                     </div>
                                 }
+                            </div>
                         }
                         else
                         {
-                            <div class="graph-node satellite" style="--angle: 0deg; --dist: 60px;"></div>
+                            <div @key='"satellite-placeholders-container"' style="display: contents;">
-                            <div class="graph-node satellite" style="--angle: 120deg; --dist: 50px;"></div>
+                                <div @key='"satellite-placeholder-0"' class="graph-node satellite" style="--angle: 0deg; --dist: 60px;"></div>
-                            <div class="graph-node satellite" style="--angle: 240deg; --dist: 70px;"></div>
+                                <div @key='"satellite-placeholder-1"' class="graph-node satellite" style="--angle: 120deg; --dist: 50px;"></div>
+                                <div @key='"satellite-placeholder-2"' class="graph-node satellite" style="--angle: 240deg; --dist: 70px;"></div>
+                            </div>
                         }
                         
                         <div class="active-node-label">
@@ -111,10 +115,10 @@
                     <div class="quiz-preview">
                         @if (_profile?.RecentQuizzes != null && _profile.RecentQuizzes.Any())
                         {
-                            <div class="quiz-history-list">
+                            <div @key='"quiz-history-list"' class="quiz-history-list">
                                 @foreach (var quiz in _profile.RecentQuizzes)
                                 {
-                                    <div class="quiz-history-item">
+                                    <div @key="quiz.Id" class="quiz-history-item">
                                         <div class="quiz-item-header">
                                             <span class="quiz-topic">@quiz.Topic</span>
                                             <span class="quiz-score badge @(quiz.Percentage >= 80 ? "badge-success" : quiz.Percentage >= 50 ? "badge-warning" : "badge-danger")">
@@ -130,7 +134,7 @@
                         }
                         else
                         {
-                            <div class="empty-quiz-state">
+                            <div @key='"empty-quiz-state"' class="empty-quiz-state">
                                 <p class="question">Brak rozwiązanych quizów</p>
                                 <p class="sub-text">Rozwiązuj quizy w trakcie czytania książek, aby śledzić swoje postępy.</p>
                             </div>

src/NexusReader.UI.Shared/Pages/Dashboard.razor.css

@@ -17,16 +17,16 @@
     display: flex;
     justify-content: center;
     overflow: hidden;
-    background: #0d0d0d;
+    background: var(--bg-surface);
-    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
+    border-bottom: 1px solid var(--border);
 }
 
 .header-grid-bg {
     position: absolute;
     inset: 0;
     background-image: 
-        linear-gradient(rgba(255,255,255,0.03) 1px, transparent 1px),
+        linear-gradient(var(--border) 1px, transparent 1px),
-        linear-gradient(90deg, rgba(255,255,255,0.03) 1px, transparent 1px);
+        linear-gradient(90deg, var(--border) 1px, transparent 1px);
     background-size: 60px 60px;
     background-position: center;
     mask-image: radial-gradient(circle at center, black, transparent 80%);
@@ -52,10 +52,10 @@
     height: 100%;
     border-radius: 50%;
     object-fit: cover;
-    border: 3px solid #1a1a1a;
+    border: 3px solid var(--border);
     position: relative;
     z-index: 2;
-    background: #222;
+    background: var(--bg-surface);
 }
 
 .avatar-glow {
@@ -78,7 +78,7 @@
     font-family: var(--nexus-font-sans);
     font-size: 1.25rem;
     font-weight: 500;
-    color: #ffffff;
+    color: var(--text-main);
     letter-spacing: 1px;
     text-transform: lowercase;
 }
@@ -103,17 +103,17 @@
 
 .status-pill {
     padding: 0.6rem 1.25rem;
-    background: rgba(16, 185, 129, 0.05);
+    background: var(--bg-base);
-    border: 1px solid rgba(16, 185, 129, 0.3);
+    border: 1px solid var(--border);
     border-radius: 100px;
     display: flex;
     gap: 0.5rem;
     font-size: 0.9rem;
-    box-shadow: 0 0 15px rgba(16, 185, 129, 0.1);
+    box-shadow: 0 0 15px rgba(16, 185, 129, 0.05);
 }
 
-.pill-label { color: #A0A0A0; }
+.pill-label { color: var(--text-muted); }
-.pill-value { color: #ffffff; font-weight: 600; }
+.pill-value { color: var(--text-main); font-weight: 600; }
 
 /* --- Dashboard Content --- */
 .dashboard-content {
@@ -127,7 +127,7 @@
     font-family: var(--nexus-font-serif);
     font-size: 2rem;
     margin-bottom: 2rem;
-    color: #ffffff;
+    color: var(--text-main);
 }
 
 .main-grid {
@@ -137,18 +137,18 @@
 }
 
 .glass-panel {
-    background: #1a1a1e;
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
     border-radius: 12px;
     padding: 1.5rem;
     transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
 }
 
 .glass-panel:hover {
-    background: #1e1e24;
+    background: var(--bg-surface);
-    border-color: rgba(16, 185, 129, 0.2);
+    border-color: var(--accent);
     transform: translateY(-4px);
-    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
+    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
 }
 
 /* Reading Card */
@@ -161,7 +161,7 @@
 .reading-card h3 {
     font-size: 1.1rem;
     font-weight: 600;
-    color: #E0E0E0;
+    color: var(--text-main);
     margin: 0;
 }
 
@@ -178,7 +178,7 @@
 .reading-thumb img {
     width: 100%;
     border-radius: 12px;
-    box-shadow: 0 10px 30px rgba(0,0,0,0.5);
+    box-shadow: 0 10px 30px rgba(0,0,0,0.15);
 }
 
 .reading-info {
@@ -196,12 +196,12 @@
 
 .chapter-label {
     font-size: 0.85rem;
-    color: #A0A0A0;
+    color: var(--text-muted);
 }
 
 .progress-container {
     height: 8px;
-    background: rgba(255, 255, 255, 0.05);
+    background: var(--border);
     border-radius: 4px;
     position: relative;
 }
@@ -228,13 +228,13 @@
 
 .progress-detail {
     font-size: 0.8rem;
-    color: #666;
+    color: var(--text-muted);
 }
 
 .reading-desc {
     font-size: 0.85rem;
     line-height: 1.6;
-    color: #888;
+    color: var(--text-muted);
     margin: 0;
 }
 
@@ -261,7 +261,7 @@
     margin: 0;
     font-size: 1rem;
     font-weight: 600;
-    color: #E0E0E0;
+    color: var(--text-main);
 }
 
 /* Graph Placeholder */
@@ -325,7 +325,7 @@
 
 .question {
     font-size: 0.95rem;
-    color: #E0E0E0;
+    color: var(--text-main);
 }
 
 .quiz-options {
@@ -336,13 +336,14 @@
 
 .quiz-option {
     padding: 0.75rem 1rem;
-    background: rgba(255, 255, 255, 0.02);
+    background: var(--bg-base);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
     border-radius: 10px;
     font-size: 0.9rem;
     display: flex;
     gap: 0.75rem;
     cursor: pointer;
+    color: var(--text-main);
 }
 
 .quiz-option.active {
@@ -372,9 +373,9 @@
 }
 
 .btn-nexus.secondary {
-    background: rgba(255, 255, 255, 0.05);
+    background: var(--bg-base);
-    color: #fff;
+    color: var(--text-main);
-    border: 1px solid rgba(255, 255, 255, 0.1);
+    border: 1px solid var(--border);
 }
 
 .btn-nexus:hover {
@@ -417,16 +418,16 @@
 }
 
 .quiz-history-item {
-    background: rgba(255, 255, 255, 0.02);
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
     border-radius: 12px;
     padding: 1rem;
     transition: all 0.2s ease;
 }
 
 .quiz-history-item:hover {
-    background: rgba(255, 255, 255, 0.04);
+    background: var(--bg-base);
-    border-color: rgba(255, 255, 255, 0.1);
+    border-color: var(--border);
 }
 
 .quiz-item-header {
@@ -440,13 +441,13 @@
 .quiz-topic {
     font-size: 0.95rem;
     font-weight: 500;
-    color: #ffffff;
+    color: var(--text-main);
 }
 
 .quiz-item-meta {
     display: flex;
     font-size: 0.75rem;
-    color: #666666;
+    color: var(--text-muted);
 }
 
 .badge {
@@ -481,7 +482,7 @@
 
 .empty-quiz-state .sub-text {
     font-size: 0.8rem;
-    color: #666666;
+    color: var(--text-muted);
     margin-top: 0.5rem;
 }
 
@@ -489,8 +490,8 @@
 .concept-detail-toast {
     margin-top: 1rem;
     padding: 0.75rem 1rem;
-    background: rgba(255, 255, 255, 0.02);
+    background: var(--bg-base);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
     border-radius: 12px;
     min-height: 80px;
     display: flex;
@@ -514,7 +515,7 @@
 .concept-content {
     font-size: 0.85rem;
     line-height: 1.4;
-    color: #E0E0E0;
+    color: var(--text-main);
     margin: 0;
     display: -webkit-box;
     -webkit-line-clamp: 2;
@@ -603,8 +604,8 @@
 /* --- Architecture Guide Block --- */
 .architecture-guide-panel {
     margin-top: 2.5rem;
-    background: #1a1a1e;
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
     border-radius: 12px;
     padding: 2rem;
 }
@@ -618,7 +619,7 @@
 .architecture-content h3 {
     font-size: 1.5rem;
     font-weight: 700;
-    color: #ffffff;
+    color: var(--text-main);
     margin-bottom: 1.25rem;
     letter-spacing: -0.01em;
 }
@@ -626,16 +627,103 @@
 .architecture-content p {
     font-size: 0.95rem;
     line-height: 1.6;
-    color: #e4e4e7;
+    color: var(--text-main);
     margin-bottom: 1.25rem;
 }
 
 .architecture-content code {
-    background: rgba(255, 255, 255, 0.05);
+    background: var(--bg-base);
     color: #10b981;
     padding: 0.2rem 0.4rem;
     border-radius: 4px;
     font-size: 0.85rem;
 }
 
+/* ============================================================
+   LIGHT THEME OVERRIDES — "Warm Paper / Soft Sepia"
+   ============================================================ */
+
+.theme-light .username::before,
+.theme-light .username::after {
+    color: var(--accent);
+}
+
+.theme-light .avatar-glow {
+    background: var(--accent);
+    filter: blur(15px);
+    opacity: 0.2;
+}
+
+.theme-light .progress-container {
+    background: #e4e1d9;
+}
+
+.theme-light .progress-bar {
+    background: var(--accent);
+    box-shadow: 0 0 8px rgba(16, 185, 129, 0.2);
+}
+
+.theme-light .progress-bubble {
+    background: var(--accent);
+    color: #ffffff;
+}
+
+.theme-light .graph-node {
+    background: rgba(0, 0, 0, 0.06);
+    border: 1px solid rgba(0, 0, 0, 0.08);
+}
+
+.theme-light .graph-node.central {
+    background: var(--accent);
+    box-shadow: 0 0 12px rgba(16, 185, 129, 0.2);
+}
+
+.theme-light .graph-node.satellite {
+    background: rgba(16, 185, 129, 0.15);
+    border: 1px solid var(--accent);
+}
+
+.theme-light .graph-node.satellite:hover {
+    background: var(--accent);
+    box-shadow: 0 0 10px var(--accent);
+}
+
+.theme-light .active-node-label {
+    background: rgba(16, 185, 129, 0.06);
+    border: 1px solid var(--accent);
+    color: var(--accent);
+}
+
+.theme-light .quiz-option.active {
+    background: rgba(16, 185, 129, 0.06);
+    border-color: var(--accent);
+    color: var(--accent);
+}
+
+.theme-light .btn-nexus.primary {
+    background: var(--accent);
+    color: #0d0d0d;
+}
+
+.theme-light .btn-nexus.primary:hover {
+    background: #059669;
+    color: #ffffff;
+}
+
+.theme-light .empty-icon {
+    color: var(--accent);
+    filter: none;
+}
+
+.theme-light .badge-success {
+    background: rgba(16, 185, 129, 0.1);
+    color: var(--accent);
+    border: 1px solid rgba(16, 185, 129, 0.2);
+}
+
+.theme-light .concept-type {
+    color: var(--accent);
+}
+
+
 

src/NexusReader.UI.Shared/Pages/Intelligence.razor.css

@@ -1,7 +1,7 @@
 .intelligence-page {
     margin: -2.5rem;
     height: 100vh;
-    background: #121214;
+    background: var(--bg-base);
     display: flex;
     flex-direction: column;
     overflow: hidden;
@@ -45,11 +45,11 @@
     background: transparent;
 }
 .chat-thread-container::-webkit-scrollbar-thumb {
-    background: rgba(16, 185, 129, 0.2);
+    background: var(--accent-glow);
     border-radius: 4px;
 }
 .chat-thread-container::-webkit-scrollbar-thumb:hover {
-    background: rgba(16, 185, 129, 0.4);
+    background: var(--accent);
 }
 
 .chat-bubbles-scroll {
@@ -78,7 +78,7 @@
 
 .welcome-prompt {
     font-family: var(--nexus-font-sans, inherit);
-    color: #e4e4e7;
+    color: var(--text-main);
     font-size: 1.35rem;
     font-weight: 500;
     letter-spacing: -0.2px;
@@ -87,7 +87,7 @@
 /* Input Controls */
 .chat-input-controls {
     padding: 1.5rem 4rem 3rem 4rem;
-    background: linear-gradient(to top, #121214 70%, rgba(18, 18, 20, 0));
+    background: linear-gradient(to top, var(--bg-base) 70%, transparent);
     flex-shrink: 0;
 }
 
@@ -117,13 +117,13 @@
     gap: 0.6rem;
     font-size: 0.85rem;
     font-weight: 500;
-    color: #8b8273;
+    color: var(--text-muted);
 }
 
 .nexus-select {
-    background: #1a1a1e;
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.06);
+    border: 1px solid var(--border);
-    color: #e4e4e7;
+    color: var(--text-main);
     padding: 0.4rem 2rem 0.4rem 0.75rem;
     border-radius: 8px;
     outline: none;
@@ -138,38 +138,38 @@
 }
 
 .nexus-select:focus {
-    border-color: #10b981;
+    border-color: var(--accent);
-    box-shadow: 0 0 8px rgba(16, 185, 129, 0.15);
+    box-shadow: 0 0 8px var(--accent-glow);
 }
 
 .input-field-group {
     display: flex;
-    background: #1a1a1e;
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.06);
+    border: 1px solid var(--border);
     border-radius: 12px;
     padding: 0.4rem;
     transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
-    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
+    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
 }
 
 .input-field-group:focus-within {
-    border-color: rgba(16, 185, 129, 0.5);
+    border-color: var(--accent);
-    background: #1a1a1e;
+    background: var(--bg-surface);
-    box-shadow: 0 10px 35px rgba(16, 185, 129, 0.1);
+    box-shadow: 0 10px 35px var(--accent-glow);
 }
 
 .nexus-input {
     flex-grow: 1;
     background: transparent;
     border: none;
-    color: #ffffff;
+    color: var(--text-main);
     font-size: 0.975rem;
     outline: none;
     padding: 0.5rem 1rem;
 }
 
 .nexus-input::placeholder {
-    color: #8b8273;
+    color: var(--text-muted);
 }
 
 .search-btn {
@@ -180,29 +180,31 @@
     align-items: center;
     justify-content: center;
     border-radius: 8px;
-    background: #10b981;
+    background: var(--accent);
     border: none;
-    color: #121214;
+    color: var(--bg-surface);
     cursor: pointer;
     transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
 }
 
 .search-btn:hover:not(:disabled) {
-    background: #0d9668;
+    background: var(--accent);
+    opacity: 0.9;
     transform: scale(1.02);
 }
 
 .search-btn:disabled {
-    background: rgba(26, 26, 30, 0.8);
+    background: var(--bg-base);
-    color: rgba(255, 255, 255, 0.2);
+    color: var(--text-muted);
-    border: 1px solid rgba(255, 255, 255, 0.02);
+    opacity: 0.4;
+    border: 1px solid var(--border);
     cursor: not-allowed;
 }
 
 /* Typing / Loading Indicators */
 .message-bubble.pending-bubble {
-    border-color: rgba(16, 185, 129, 0.25);
+    border-color: var(--accent-glow);
-    background: rgba(16, 185, 129, 0.03);
+    background: var(--accent-glow);
     max-width: 450px;
 }
 
@@ -216,7 +218,7 @@
 .typing-indicator span {
     width: 7px;
     height: 7px;
-    background: #10b981;
+    background: var(--accent);
     border-radius: 50%;
     display: inline-block;
     animation: typing-bounce 1.4s infinite ease-in-out both;
@@ -227,16 +229,16 @@
 
 .loading-label {
     font-size: 0.825rem;
-    color: rgba(255, 255, 255, 0.45);
+    color: var(--text-muted);
     font-style: italic;
 }
 
 .btn-spinner {
     width: 18px;
     height: 18px;
-    border: 2px solid rgba(18, 18, 20, 0.1);
+    border: 2px solid var(--border);
     border-radius: 50%;
-    border-top-color: #121214;
+    border-top-color: var(--accent);
     animation: spin 0.8s linear infinite;
 }
 
@@ -260,3 +262,66 @@
     0% { transform: rotate(0deg); }
     100% { transform: rotate(360deg); }
 }
+
+/* ============================================================
+   LIGHT THEME OVERRIDES — "Warm Paper / Soft Sepia"
+   ============================================================ */
+
+.theme-light .welcome-prompt {
+    color: var(--text-main);
+}
+
+.theme-light .welcome-icon svg {
+    stroke: var(--text-muted);
+}
+
+.theme-light .welcome-icon svg circle {
+    fill: var(--text-muted);
+}
+
+.theme-light .welcome-icon svg path[stroke^="rgba(139"] {
+    stroke: rgba(120, 113, 108, 0.4);
+}
+
+.theme-light .welcome-icon svg path[stroke^="rgba(139"][stroke-dasharray] {
+    stroke: rgba(120, 113, 108, 0.3);
+}
+
+.theme-light .input-field-group {
+    background: var(--bg-surface);
+    border: 1px solid var(--border);
+    box-shadow: 0 10px 30px rgba(139, 130, 115, 0.08);
+}
+
+.theme-light .input-field-group:focus-within {
+    border-color: var(--accent);
+    box-shadow: 0 10px 35px rgba(16, 185, 129, 0.15);
+}
+
+.theme-light .nexus-input {
+    color: var(--text-main);
+}
+
+.theme-light .nexus-input::placeholder {
+    color: var(--text-muted);
+}
+
+.theme-light .nexus-select {
+    background-color: var(--bg-surface);
+    border-color: var(--border);
+    color: var(--text-main);
+}
+
+.theme-light .nexus-select:focus {
+    border-color: var(--accent);
+    box-shadow: 0 0 8px var(--accent-glow);
+}
+
+.theme-light .chat-thread-container::-webkit-scrollbar-thumb {
+    background: rgba(0, 0, 0, 0.1);
+}
+
+.theme-light .chat-thread-container::-webkit-scrollbar-thumb:hover {
+    background: rgba(0, 0, 0, 0.2);
+}
+

src/NexusReader.UI.Shared/Pages/MyBooks.razor.css

@@ -19,13 +19,13 @@
     font-size: 2.5rem;
     font-weight: 700;
     margin: 0 0 0.5rem 0;
-    color: #ffffff;
+    color: var(--text-main);
     letter-spacing: -0.5px;
 }
 
 .header-title-section .subtitle {
     font-size: 1rem;
-    color: #a1a1aa;
+    color: var(--text-muted);
     margin: 0;
 }
 
@@ -67,27 +67,27 @@
     height: 100%;
     overflow: hidden;
     border-radius: 12px;
-    background: #1a1a1e;
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
     transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
     position: relative;
 }
 
 .book-card:hover {
     transform: translateY(-4px);
-    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.3);
+    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.1);
-    border-color: rgba(16, 185, 129, 0.2);
+    border-color: var(--accent);
 }
 
 .book-cover-container {
     position: relative;
     height: 360px;
-    background: rgba(0, 0, 0, 0.2);
+    background: rgba(0, 0, 0, 0.05);
     overflow: hidden;
     display: flex;
     align-items: center;
     justify-content: center;
-    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
+    border-bottom: 1px solid var(--border);
 }
 
 .book-cover {
@@ -145,7 +145,7 @@
     font-size: 1.2rem;
     font-weight: 600;
     margin: 0 0 0.4rem 0;
-    color: #ffffff;
+    color: var(--text-main);
     overflow: hidden;
     text-overflow: ellipsis;
     white-space: nowrap;
@@ -154,7 +154,7 @@
 
 .book-author {
     font-size: 0.9rem;
-    color: #a1a1aa;
+    color: var(--text-muted);
     margin: 0 0 1.25rem 0;
 }
 
@@ -179,7 +179,7 @@
 
 .progress-bar {
     height: 6px;
-    background: rgba(255, 255, 255, 0.05);
+    background: var(--border);
     border-radius: 3px;
     overflow: hidden;
 }
@@ -192,7 +192,7 @@
 
 .progress-text {
     font-size: 0.8rem;
-    color: #a1a1aa;
+    color: var(--text-muted);
     white-space: nowrap;
     overflow: hidden;
     text-overflow: ellipsis;
@@ -232,14 +232,14 @@
     justify-content: center;
     padding: 5rem 2rem;
     text-align: center;
-    background: #1a1a1e;
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
     border-radius: 12px;
 }
 
 .empty-icon-pulse {
     margin-bottom: 2rem;
-    color: #a1a1aa;
+    color: var(--text-muted);
     animation: pulse 3s infinite alternate;
 }
 
@@ -247,11 +247,11 @@
     font-family: var(--nexus-font-serif);
     font-size: 1.8rem;
     margin: 0 0 0.5rem 0;
-    color: #ffffff;
+    color: var(--text-main);
 }
 
 .empty-state-container p {
-    color: #a1a1aa;
+    color: var(--text-muted);
     max-width: 400px;
     margin: 0 0 2rem 0;
 }
@@ -278,14 +278,14 @@
     border-radius: 12px;
     overflow: hidden;
     height: 480px;
-    background: #1a1a1e;
+    background: var(--bg-surface);
-    border: 1px solid rgba(255, 255, 255, 0.05);
+    border: 1px solid var(--border);
     opacity: 0.6;
 }
 
 .skeleton-cover {
     height: 360px;
-    background: linear-gradient(90deg, rgba(255,255,255,0.02) 25%, rgba(255,255,255,0.06) 50%, rgba(255,255,255,0.02) 75%);
+    background: linear-gradient(90deg, var(--bg-base) 25%, var(--border) 50%, var(--bg-base) 75%);
     background-size: 200% 100%;
     animation: loading 1.5s infinite;
 }
@@ -298,7 +298,7 @@
 }
 
 .skeleton-line {
-    background: linear-gradient(90deg, rgba(255,255,255,0.02) 25%, rgba(255,255,255,0.06) 50%, rgba(255,255,255,0.02) 75%);
+    background: linear-gradient(90deg, var(--bg-base) 25%, var(--border) 50%, var(--bg-base) 75%);
     background-size: 200% 100%;
     animation: loading 1.5s infinite;
     border-radius: 4px;
@@ -336,9 +336,9 @@
     gap: 1.25rem;
     padding: 1.25rem 2.25rem;
     border-radius: 40px;
-    background: rgba(13, 13, 15, 0.85);
+    background: var(--bg-surface);
     backdrop-filter: blur(16px);
-    border: 1px solid rgba(255, 255, 255, 0.08);
+    border: 1px solid var(--border);
     animation: scaleIn 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
 }
 
@@ -354,7 +354,7 @@
 
 .loader-text {
     font-weight: 500;
-    color: #ffffff;
+    color: var(--text-main);
     font-size: 0.95rem;
 }
 
@@ -383,3 +383,27 @@
     from { transform: translate(-50%, -50%) scale(0.9); opacity: 0; }
     to { transform: translate(-50%, -50%) scale(1); opacity: 1; }
 }
+
+/* ============================================
+   LIGHT THEME OVERRIDES — Warm Paper / Soft Sepia
+   ============================================ */
+
+.theme-light .book-card:hover {
+    box-shadow: 0 12px 30px rgba(139, 130, 115, 0.15);
+}
+
+.theme-light .book-cover-container {
+    background: rgba(0, 0, 0, 0.03);
+}
+
+.theme-light .cover-overlay {
+    background: rgba(0, 0, 0, 0.5);
+}
+
+.theme-light .book-card:hover .read-action {
+    color: #292524;
+}
+
+.theme-light .progress-bar {
+    background: #e4e1d9;
+}

src/NexusReader.UI.Shared/Pages/Settings.razor.css

@@ -72,3 +72,40 @@
     from { opacity: 0; transform: translateY(15px); }
     to { opacity: 1; transform: translateY(0); }
 }
+
+/* ============================================================
+   LIGHT THEME OVERRIDES — "Warm Paper / Soft Sepia"
+   ============================================================ */
+
+.theme-light .settings-page > h1 {
+    background: none;
+    -webkit-text-fill-color: initial;
+    color: var(--text-main);
+}
+
+.theme-light .settings-page > p {
+    color: var(--text-muted);
+}
+
+.theme-light .settings-section h2 {
+    color: var(--text-main);
+}
+
+.theme-light .settings-section p {
+    color: var(--text-muted);
+}
+
+.theme-light .diag-btn {
+    background: rgba(16, 185, 129, 0.05);
+    color: var(--accent);
+    border: 1px solid rgba(16, 185, 129, 0.2);
+}
+
+.theme-light .diag-btn:hover {
+    background: var(--accent);
+    color: #ffffff;
+    border-color: var(--accent);
+    box-shadow: 0 0 10px rgba(16, 185, 129, 0.2);
+    transform: translateY(-2px);
+}
+

src/NexusReader.UI.Shared/Services/IThemeService.cs

@@ -1,9 +1,14 @@
+using NexusReader.Domain.Enums;
+
 namespace NexusReader.UI.Shared.Services;
 
 public interface IThemeService
 {
+    ThemeMode Mode { get; }
     bool IsLightMode { get; }
-    event Func<Task>? OnThemeChanged;
+    event Action<ThemeMode>? OnThemeChanged;
+    
     Task InitializeAsync();
+    Task SetThemeAsync(ThemeMode mode);
     Task ToggleTheme();
 }

src/NexusReader.UI.Shared/Services/ThemeService.cs

@@ -1,42 +1,155 @@
 using Microsoft.JSInterop;
+using NexusReader.Domain.Enums;
+using NexusReader.Application.Abstractions.Services;
 
 namespace NexusReader.UI.Shared.Services;
 
 public sealed class ThemeService : IThemeService
 {
     private readonly IJSRuntime _jsRuntime;
-    public bool IsLightMode { get; private set; } = false;
+    private readonly IUserPreferenceStore _userPreferenceStore;
-    public event Func<Task>? OnThemeChanged;
+    private readonly SemaphoreSlim _semaphore = new(1, 1);
+    private bool _isInitialized;
+    private bool _systemPrefersLight;
 
-    public ThemeService(IJSRuntime jsRuntime)
+    public ThemeMode Mode { get; private set; } = ThemeMode.System;
+
+    public bool IsLightMode => Mode == ThemeMode.LightSepia || (Mode == ThemeMode.System && _systemPrefersLight);
+
+    public event Action<ThemeMode>? OnThemeChanged;
+
+    public ThemeService(IJSRuntime jsRuntime, IUserPreferenceStore userPreferenceStore)
     {
         _jsRuntime = jsRuntime;
+        _userPreferenceStore = userPreferenceStore;
     }
 
     public async Task InitializeAsync()
     {
+        if (_isInitialized) return;
+
+        await _semaphore.WaitAsync();
         try
         {
-            IsLightMode = await _jsRuntime.InvokeAsync<bool>("themeInterop.isLightMode");
+            if (_isInitialized) return;
-            if (OnThemeChanged != null) await OnThemeChanged();
+
+            ThemeMode localMode = ThemeMode.System;
+            try
+            {
+                var cachedThemeVal = await _jsRuntime.InvokeAsync<string?>("localStorage.getItem", "theme-mode");
+                if (Enum.TryParse<ThemeMode>(cachedThemeVal, out var parsedMode))
+                {
+                    localMode = parsedMode;
+                }
+                else if (cachedThemeVal == "light" || cachedThemeVal == "theme-light")
+                {
+                    localMode = ThemeMode.LightSepia;
+                }
+                else if (cachedThemeVal == "dark" || cachedThemeVal == "theme-dark")
+                {
+                    localMode = ThemeMode.Dark;
+                }
+                
+                _systemPrefersLight = await _jsRuntime.InvokeAsync<bool>("themeInterop.isSystemLight");
             }
             catch
             {
-            // Fail silently during prerendering or if JS is not available yet
+                // Silent catch for pre-rendering or unit tests
+            }
+
+            Mode = localMode;
+            _isInitialized = true;
+            
+            await ApplyThemeToDomAsync(Mode);
+
+            // Asynchronously sync with the cloud to check for updates from other devices
+            _ = Task.Run(async () =>
+            {
+                try
+                {
+                    var cloudResult = await _userPreferenceStore.GetThemePreferenceAsync();
+                    if (cloudResult.IsSuccess && cloudResult.Value != Mode)
+                    {
+                        await SetThemeInternalAsync(cloudResult.Value, saveToCloud: false);
+                    }
+                }
+                catch
+                {
+                    // Fail silently for background task/network errors
+                }
+            });
+        }
+        finally
+        {
+            _semaphore.Release();
+        }
+    }
+
+    public async Task SetThemeAsync(ThemeMode mode)
+    {
+        await SetThemeInternalAsync(mode, saveToCloud: true);
+    }
+
+    private async Task SetThemeInternalAsync(ThemeMode mode, bool saveToCloud)
+    {
+        await _semaphore.WaitAsync();
+        try
+        {
+            if (Mode == mode && _isInitialized) return;
+
+            Mode = mode;
+            _isInitialized = true;
+
+            await ApplyThemeToDomAsync(mode);
+
+            OnThemeChanged?.Invoke(mode);
+
+            if (saveToCloud)
+            {
+                _ = Task.Run(async () =>
+                {
+                    try
+                    {
+                        await _userPreferenceStore.SaveThemePreferenceAsync(mode);
+                    }
+                    catch
+                    {
+                        // Fail silently for background cloud sync errors
+                    }
+                });
+            }
+        }
+        finally
+        {
+            _semaphore.Release();
         }
     }
 
     public async Task ToggleTheme()
     {
-        IsLightMode = !IsLightMode;
+        var nextMode = IsLightMode ? ThemeMode.Dark : ThemeMode.LightSepia;
+        await SetThemeAsync(nextMode);
+    }
+
+    private async Task ApplyThemeToDomAsync(ThemeMode mode)
+    {
         try
         {
-            await _jsRuntime.InvokeVoidAsync("themeInterop.setLightMode", IsLightMode);
+            string themeClass = "theme-dark"; // Default
+            if (mode == ThemeMode.LightSepia)
+            {
+                themeClass = "theme-light";
+            }
+            else if (mode == ThemeMode.System)
+            {
+                themeClass = _systemPrefersLight ? "theme-light" : "theme-dark";
+            }
+
+            await _jsRuntime.InvokeVoidAsync("themeInterop.setCachedTheme", themeClass, ((int)mode).ToString());
         }
         catch
         {
-            // Fail silently
+            // Silent catch for pre-rendering
-        }
+        }
-        if (OnThemeChanged != null) await OnThemeChanged();
     }
 }

src/NexusReader.UI.Shared/_Imports.razor

@@ -21,3 +21,4 @@
 @using NexusReader.Application.DTOs.User
 @using NexusReader.Application.Queries.Reader
 @using NexusReader.Application.Queries.Recommendations
+@using NexusReader.Domain.Enums

src/NexusReader.UI.Shared/wwwroot/app.css

@@ -1,17 +1,27 @@
 @import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600&family=Merriweather:ital,wght@0,300;0,400;0,700;1,400&display=swap');
 
 :root {
-    --nexus-neon: #00ff99;
+    /* Semantic design tokens - default to Modern Deep Dark (Dark Mode) */
-    --nexus-neon-glow: rgba(0, 255, 153, 0.3);
+    --bg-base: #121214;
-    --nexus-bg: #121214;
+    --bg-surface: #1a1a1e;
-    --nexus-card: #1a1a1e;
+    --text-main: #ffffff;
-    --nexus-text: #ffffff;
+    --text-muted: #a1a1aa;
+    --accent: #00ff99;
+    --accent-glow: rgba(0, 255, 153, 0.3);
+
+    /* Legacy mapping for backwards compatibility */
+    --nexus-neon: var(--accent);
+    --nexus-neon-glow: var(--accent-glow);
+    --nexus-bg: var(--bg-base);
+    --nexus-card: var(--bg-surface);
+    --nexus-text: var(--text-main);
     --nexus-paper: #F9F9F9;
     --nexus-font-sans: 'Inter', sans-serif;
     --nexus-font-serif: 'Merriweather', serif;
 
     /* Global Selection Style Override */
     --nexus-selection: rgba(0, 255, 153, 0.25);
+    --nexus-accent: var(--accent);
 
     /* Graph Nodes Theme Custom Properties (Dark Mode) */
     --nexus-graph-bg: radial-gradient(circle, #1a1a1a 0%, #121212 100%);
@@ -56,6 +66,7 @@
 
 
 /* Global Semantic Theme Mapping */
+:root {
     --nexus-primary: var(--nexus-neon);
     --nexus-primary-glow: var(--nexus-neon-glow);
     --nexus-primary-hover: #00e688;
@@ -133,11 +144,38 @@
 }
 
 
+.theme-dark {
+    /* Semantic design tokens - Modern Deep Dark */
+    --bg-base: #121214;
+    --bg-surface: #1a1a1e;
+    --text-main: #ffffff;
+    --text-muted: #a1a1aa;
+    --accent: #00ff99;
+    --accent-glow: rgba(0, 255, 153, 0.3);
+
+    /* Legacy mapping for backwards compatibility */
+    --nexus-bg: var(--bg-base);
+    --nexus-card: var(--bg-surface);
+    --nexus-text: var(--text-main);
+    --nexus-selection: rgba(0, 255, 153, 0.25);
+    --nexus-accent: var(--accent);
+}
+
 .theme-light {
-    --nexus-bg: #f4f1ea;
+    /* Semantic design tokens - Warm Paper / Soft Sepia */
-    --nexus-card: #ffffff;
+    --bg-base: #f4f1ea;
-    --nexus-text: #2d2a26;
+    --bg-surface: #ffffff;
+    --text-main: #2d2a26;
+    --text-muted: #78716c;
+    --accent: #10b981;
+    --accent-glow: rgba(16, 185, 129, 0.2);
+
+    /* Legacy mapping for backwards compatibility */
+    --nexus-bg: var(--bg-base);
+    --nexus-card: var(--bg-surface);
+    --nexus-text: var(--text-main);
     --nexus-selection: rgba(16, 185, 129, 0.18);
+    --nexus-accent: var(--accent);
 
     /* Graph Nodes Theme Custom Properties (Light Mode) */
     --nexus-graph-bg: radial-gradient(circle, #ffffff 0%, #e8e4da 100%);

src/NexusReader.UI.Shared/wwwroot/js/theme.js

@@ -1,14 +1,25 @@
 window.themeInterop = {
+    isSystemLight: function () {
+        return window.matchMedia && window.matchMedia('(prefers-color-scheme: light)').matches;
+    },
+    setCachedTheme: function (themeClass, modeValue) {
+        localStorage.setItem('theme-mode', modeValue);
+        localStorage.setItem('theme', themeClass === 'theme-light' ? 'light' : 'dark');
+        
+        if (themeClass === 'theme-light') {
+            document.documentElement.classList.add('theme-light');
+            document.documentElement.classList.remove('theme-dark');
+        } else {
+            document.documentElement.classList.add('theme-dark');
+            document.documentElement.classList.remove('theme-light');
+        }
+    },
     isLightMode: function () {
         return document.documentElement.classList.contains('theme-light');
     },
     setLightMode: function (isLight) {
-        if (isLight) {
+        var themeClass = isLight ? 'theme-light' : 'theme-dark';
-            document.documentElement.classList.add('theme-light');
+        var modeValue = isLight ? '2' : '1';
-            localStorage.setItem('theme', 'light');
+        this.setCachedTheme(themeClass, modeValue);
-        } else {
-            document.documentElement.classList.remove('theme-light');
-            localStorage.setItem('theme', 'dark');
-        }
     }
 };

src/NexusReader.Web.Client/Program.cs

@@ -17,7 +17,8 @@ var builder = WebAssemblyHostBuilder.CreateDefault(args);
 // Platform & UI Services
 builder.Services.AddScoped<IPlatformService, WebPlatformService>();
 builder.Services.AddScoped<INativeStorageService, WebStorageService>();
-builder.Services.AddScoped<IThemeService, ThemeService>();
+builder.Services.AddSingleton<IUserPreferenceStore, CloudUserPreferenceStore>();
+builder.Services.AddSingleton<IThemeService, ThemeService>();
 // Feature settings (avoiding direct raw IConfiguration injection in client pages)
 var featureSettings = builder.Configuration.GetSection("Features").Get<FeatureSettings>() ?? new FeatureSettings();
 builder.Services.AddSingleton(featureSettings);
@@ -61,6 +62,10 @@ builder.Services.AddSingleton<IQuizResultRepository>(new ThrowingQuizResultRepos
 builder.Services.AddSingleton<IConceptsMapReadRepository>(new ThrowingConceptsMapReadRepository());
 builder.Services.AddSingleton<ISyncBroadcaster>(new ThrowingSyncBroadcaster());
 builder.Services.AddSingleton<IEpubExtractor>(new ThrowingEpubExtractor());
+builder.Services.AddSingleton<IUserLibraryStore>(new ThrowingUserLibraryStore());
+builder.Services.AddSingleton<IVectorSearchStore>(new ThrowingVectorSearchStore());
+builder.Services.Configure<NexusReader.Application.Common.RagMonetizationOptions>(builder.Configuration.GetSection(NexusReader.Application.Common.RagMonetizationOptions.SectionName));
+builder.Services.AddSingleton<IChatClient>(new ThrowingChatClient());
 
 builder.Services.AddApplication();
 builder.Services.AddScoped<IEpubReader, WasmEpubReader>();
@@ -134,3 +139,37 @@ public class ThrowingEpubExtractor : IEpubExtractor
         => throw new NotSupportedException("EPUB text extraction is not supported in the WASM client.");
 }
 
+public class ThrowingUserLibraryStore : IUserLibraryStore
+{
+    public Task<List<Guid>> GetOwnedBookIdsAsync(string userId, CancellationToken cancellationToken = default)
+        => throw new NotSupportedException("UserLibrary operations are not supported in the WASM client.");
+
+    public Task<Dictionary<Guid, string>> GetBookTitlesAsync(List<Guid> bookIds, CancellationToken cancellationToken = default)
+        => throw new NotSupportedException("UserLibrary operations are not supported in the WASM client.");
+}
+
+public class ThrowingVectorSearchStore : IVectorSearchStore
+{
+    public Task<List<VectorChunk>> SearchGlobalAsync(string queryText, string tenantId, int limit, CancellationToken cancellationToken = default)
+        => throw new NotSupportedException("VectorSearch operations are not supported in the WASM client.");
+
+    public Task<List<VectorChunk>> SearchLocalAsync(string queryText, string tenantId, List<Guid> whitelistedBookIds, int limit, CancellationToken cancellationToken = default)
+        => throw new NotSupportedException("VectorSearch operations are not supported in the WASM client.");
+
+    public Task<List<VectorChunk>> SearchGlobalExcludeAsync(string queryText, string tenantId, Guid excludeBookId, int limit, CancellationToken cancellationToken = default)
+        => throw new NotSupportedException("VectorSearch operations are not supported in the WASM client.");
+}
+
+public class ThrowingChatClient : IChatClient
+{
+    public void Dispose() { }
+
+    public Task<ChatResponse> GetResponseAsync(IEnumerable<ChatMessage> chatMessages, ChatOptions? options = null, CancellationToken cancellationToken = default)
+        => throw new NotSupportedException("Chat operations are not supported in the WASM client.");
+
+    public IAsyncEnumerable<ChatResponseUpdate> GetStreamingResponseAsync(IEnumerable<ChatMessage> chatMessages, ChatOptions? options = null, CancellationToken cancellationToken = default)
+        => throw new NotSupportedException("Chat operations are not supported in the WASM client.");
+
+    public object? GetService(Type serviceType, object? serviceKey = null) => null;
+}
+

src/NexusReader.Web.Client/Services/CloudUserPreferenceStore.cs

@@ -0,0 +1,61 @@
+using System.Net.Http;
+using System.Net.Http.Json;
+using FluentResults;
+using NexusReader.Application.DTOs.User;
+using NexusReader.Domain.Enums;
+using NexusReader.Application.Abstractions.Services;
+
+namespace NexusReader.Web.Client.Services;
+
+public class CloudUserPreferenceStore : IUserPreferenceStore
+{
+    private readonly IHttpClientFactory _httpClientFactory;
+
+    public CloudUserPreferenceStore(IHttpClientFactory httpClientFactory)
+    {
+        _httpClientFactory = httpClientFactory;
+    }
+
+    private HttpClient CreateClient() => _httpClientFactory.CreateClient("NexusAPI");
+
+    public async Task<Result> SaveThemePreferenceAsync(ThemeMode mode)
+    {
+        try
+        {
+            var client = CreateClient();
+            var response = await client.PostAsJsonAsync("identity/theme", new UpdateThemeRequest(mode));
+            if (response.IsSuccessStatusCode)
+            {
+                return Result.Ok();
+            }
+            
+            var error = await response.Content.ReadAsStringAsync();
+            return Result.Fail($"Failed to save cloud theme preference: {error}");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error("Network error saving theme preference to cloud.").CausedBy(ex));
+        }
+    }
+
+    public async Task<Result<ThemeMode>> GetThemePreferenceAsync()
+    {
+        try
+        {
+            var client = CreateClient();
+            var response = await client.GetAsync("identity/profile");
+            if (response.IsSuccessStatusCode)
+            {
+                var profile = await response.Content.ReadFromJsonAsync<UserProfileDto>();
+                return profile != null 
+                    ? Result.Ok(profile.ThemePreference) 
+                    : Result.Fail("Failed to deserialize profile response.");
+            }
+            return Result.Fail($"Failed to fetch theme preference from cloud: {response.ReasonPhrase}");
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error("Network error retrieving theme preference from cloud.").CausedBy(ex));
+        }
+    }
+}

src/NexusReader.Web/Components/App.razor

@@ -11,14 +11,29 @@
 
     <script>
         (function () {
-            const savedTheme = localStorage.getItem('theme');
+            try {
-            const systemPrefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
+                var themeMode = localStorage.getItem('theme-mode');
-            const isLight = savedTheme === 'light' || (!savedTheme && !systemPrefersDark);
+                var savedTheme = localStorage.getItem('theme');
+                var isLight = false;
+                
+                if (themeMode === '2' || savedTheme === 'light') {
+                    isLight = true;
+                } else if (themeMode === '1' || savedTheme === 'dark') {
+                    isLight = false;
+                } else {
+                    isLight = window.matchMedia && window.matchMedia('(prefers-color-scheme: light)').matches;
+                }
+                
                 if (isLight) {
                     document.documentElement.classList.add('theme-light');
+                    document.documentElement.classList.remove('theme-dark');
                 } else {
+                    document.documentElement.classList.add('theme-dark');
                     document.documentElement.classList.remove('theme-light');
                 }
+            } catch (e) {
+                // Fail silently
+            }
         })();
     </script>
 

src/NexusReader.Web/Program.cs

@@ -52,7 +52,9 @@ builder.Services.AddHttpContextAccessor();
 
 builder.Services.AddScoped<IPlatformService, WebPlatformService>();
 builder.Services.AddScoped<INativeStorageService, NexusReader.Web.Services.NativeStorageService>();
-builder.Services.AddScoped<IThemeService, ThemeService>();
+builder.Services.AddScoped<IUserPreferenceStore, NexusReader.Web.Services.ServerUserPreferenceStore>();
+builder.Services.AddScoped<IThemeService, NexusReader.Web.Services.ServerThemeService>();
+builder.Services.AddScoped<IRecommendationService, NexusReader.Web.Services.ServerRecommendationService>();
 // Feature settings (avoiding direct raw IConfiguration injection in client pages)
 var featureSettings = builder.Configuration.GetSection("Features").Get<FeatureSettings>() ?? new FeatureSettings();
 builder.Services.AddSingleton(featureSettings);
@@ -753,6 +755,20 @@ app.MapGet("/identity/profile", async (ClaimsPrincipal user, IMediator mediator)
     return Results.Ok(result.Value);
 }).RequireAuthorization();
 
+app.MapPost("/identity/theme", async (
+    [Microsoft.AspNetCore.Mvc.FromBody] NexusReader.Application.DTOs.User.UpdateThemeRequest request,
+    ClaimsPrincipal user,
+    IMediator mediator) =>
+{
+    var userId = user.FindFirstValue(ClaimTypes.NameIdentifier);
+    if (string.IsNullOrEmpty(userId)) return Results.Unauthorized();
+
+    var result = await mediator.Send(new NexusReader.Application.Commands.User.UpdateThemeCommand(userId, request.Mode));
+    if (result.IsFailed) return Results.BadRequest(result.Errors.FirstOrDefault()?.Message);
+
+    return Results.Ok();
+}).RequireAuthorization();
+
 app.MapRazorComponents<App>()
     .AddInteractiveServerRenderMode()
     .AddInteractiveWebAssemblyRenderMode()

src/NexusReader.Web/Services/ServerRecommendationService.cs

@@ -0,0 +1,50 @@
+using System.Collections.Generic;
+using System.Security.Claims;
+using System.Threading;
+using System.Threading.Tasks;
+using FluentResults;
+using MediatR;
+using Microsoft.AspNetCore.Http;
+using NexusReader.Application.Queries.Recommendations;
+using NexusReader.UI.Shared.Services;
+
+namespace NexusReader.Web.Services;
+
+/// <summary>
+/// Server-side implementation of <see cref="IRecommendationService"/> that executes
+/// the MediatR query directly inside the Web Server's request context.
+/// </summary>
+public sealed class ServerRecommendationService : IRecommendationService
+{
+    private readonly IMediator _mediator;
+    private readonly IHttpContextAccessor _httpContextAccessor;
+
+    public ServerRecommendationService(IMediator mediator, IHttpContextAccessor httpContextAccessor)
+    {
+        _mediator = mediator;
+        _httpContextAccessor = httpContextAccessor;
+    }
+
+    public async Task<List<RecommendationDto>?> GetRecommendationsAsync(CancellationToken cancellationToken = default)
+    {
+        var httpContext = _httpContextAccessor.HttpContext;
+        if (httpContext?.User == null)
+        {
+            return new List<RecommendationDto>();
+        }
+
+        var userId = httpContext.User.FindFirstValue(ClaimTypes.NameIdentifier);
+        if (string.IsNullOrEmpty(userId))
+        {
+            return new List<RecommendationDto>();
+        }
+
+        var result = await _mediator.Send(new GetContextualRecommendationsQuery(userId), cancellationToken);
+        if (result.IsSuccess && result.Value != null)
+        {
+            return result.Value.Recommendations;
+        }
+
+        return new List<RecommendationDto>();
+    }
+}

src/NexusReader.Web/Services/ServerThemeService.cs

@@ -0,0 +1,21 @@
+using NexusReader.Domain.Enums;
+using NexusReader.UI.Shared.Services;
+
+namespace NexusReader.Web.Services;
+
+public sealed class ServerThemeService : IThemeService
+{
+    public ThemeMode Mode => ThemeMode.System;
+    public bool IsLightMode => false;
+
+    // Explicit event implementation to avoid CS0067 warning about unused events on the server
+    public event Action<ThemeMode>? OnThemeChanged
+    {
+        add { }
+        remove { }
+    }
+
+    public Task InitializeAsync() => Task.CompletedTask;
+    public Task SetThemeAsync(ThemeMode mode) => Task.CompletedTask;
+    public Task ToggleTheme() => Task.CompletedTask;
+}

src/NexusReader.Web/Services/ServerUserPreferenceStore.cs

@@ -0,0 +1,78 @@
+using System.Security.Claims;
+using FluentResults;
+using Microsoft.AspNetCore.Http;
+using Microsoft.EntityFrameworkCore;
+using NexusReader.Data.Persistence;
+using NexusReader.Domain.Enums;
+using NexusReader.Application.Abstractions.Services;
+
+namespace NexusReader.Web.Services;
+
+public class ServerUserPreferenceStore : IUserPreferenceStore
+{
+    private readonly IDbContextFactory<AppDbContext> _dbContextFactory;
+    private readonly IHttpContextAccessor _httpContextAccessor;
+
+    public ServerUserPreferenceStore(
+        IDbContextFactory<AppDbContext> dbContextFactory,
+        IHttpContextAccessor httpContextAccessor)
+    {
+        _dbContextFactory = dbContextFactory;
+        _httpContextAccessor = httpContextAccessor;
+    }
+
+    public async Task<Result> SaveThemePreferenceAsync(ThemeMode mode)
+    {
+        var userId = _httpContextAccessor.HttpContext?.User.FindFirstValue(ClaimTypes.NameIdentifier);
+        if (string.IsNullOrEmpty(userId))
+        {
+            return Result.Fail("User is not authenticated on the server.");
+        }
+
+        try
+        {
+            using var dbContext = await _dbContextFactory.CreateDbContextAsync();
+            var user = await dbContext.Users
+                .AsTracking()
+                .FirstOrDefaultAsync(u => u.Id == userId);
+                
+            if (user == null)
+            {
+                return Result.Fail("User not found in database.");
+            }
+
+            user.ThemePreference = mode;
+            await dbContext.SaveChangesAsync();
+            return Result.Ok();
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error("Database failure updating theme preference.").CausedBy(ex));
+        }
+    }
+
+    public async Task<Result<ThemeMode>> GetThemePreferenceAsync()
+    {
+        var userId = _httpContextAccessor.HttpContext?.User.FindFirstValue(ClaimTypes.NameIdentifier);
+        if (string.IsNullOrEmpty(userId))
+        {
+            return Result.Fail("User is not authenticated on the server.");
+        }
+
+        try
+        {
+            using var dbContext = await _dbContextFactory.CreateDbContextAsync();
+            var user = await dbContext.Users.FirstOrDefaultAsync(u => u.Id == userId);
+            if (user == null)
+            {
+                return Result.Fail("User not found in database.");
+            }
+
+            return Result.Ok(user.ThemePreference);
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error("Database failure reading theme preference.").CausedBy(ex));
+        }
+    }
+}