fix: ensure user-specific ebook tracking and auto-provisioning for progress sync

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

@@ -5,5 +5,5 @@ namespace NexusReader.Application.Abstractions.Services;
 
 public interface IEpubService
 {
-    Task<Result<ReaderPageViewModel>> GetEpubContentAsync(int chapterIndex);
+    Task<Result<ReaderPageViewModel>> GetEpubContentAsync(int chapterIndex, string? userId = null);
 }

src/NexusReader.Application/Queries/Reader/GetReaderPageQuery.cs

@@ -2,4 +2,4 @@ using NexusReader.Application.Abstractions.Messaging;
 
 namespace NexusReader.Application.Queries.Reader;
 
-public record GetReaderPageQuery(int ChapterIndex = 0) : IQuery<ReaderPageViewModel>;
+public record GetReaderPageQuery(int ChapterIndex = 0, string? UserId = null) : IQuery<ReaderPageViewModel>;

src/NexusReader.Application/Queries/Reader/GetReaderPageQueryHandler.cs

@@ -15,6 +15,6 @@ internal sealed class GetReaderPageQueryHandler : IQueryHandler<GetReaderPageQue
 
     public async Task<Result<ReaderPageViewModel>> Handle(GetReaderPageQuery request, CancellationToken cancellationToken)
     {
-        return await _epubService.GetEpubContentAsync(request.ChapterIndex);
+        return await _epubService.GetEpubContentAsync(request.ChapterIndex, request.UserId);
     }
 }

src/NexusReader.Infrastructure/Services/EpubService.cs

@@ -21,7 +21,7 @@ public class EpubService : IEpubService
         _dbContextFactory = dbContextFactory;
     }
 
-    public async Task<Result<ReaderPageViewModel>> GetEpubContentAsync(int chapterIndex)
+    public async Task<Result<ReaderPageViewModel>> GetEpubContentAsync(int chapterIndex, string? userId = null)
     {
         try
         {
@@ -109,14 +109,29 @@ public class EpubService : IEpubService
                 blocks.Add(CreateAiTrigger($"trigger-{blockCounter++}"));
             }
 
-            // Find the EbookId from DB for this file
+            // Find the EbookId from DB for this file AND this user
             using var context = await _dbContextFactory.CreateDbContextAsync();
-            var ebookId = await context.Ebooks
-                .Where(e => e.FilePath.Contains("book.epub"))
-                .Select(e => e.Id)
+            var ebook = await context.Ebooks
+                .Where(e => e.FilePath.Contains("book.epub") && (userId == null || e.UserId == userId))
                 .FirstOrDefaultAsync();
 
-            return Result.Ok(new ReaderPageViewModel(blocks, chapterIndex, readingOrder.Count, chapterTitle, ebookId));
+            // Auto-provision if not found for this user (convenience for dev)
+            if (ebook == null && !string.IsNullOrEmpty(userId))
+            {
+                var author = await context.Authors.FirstOrDefaultAsync() ?? new Author { Name = "Unknown Author" };
+                ebook = new Ebook
+                {
+                    Title = "Lives of the Most Excellent Painters, Sculptors, and Architects",
+                    FilePath = "wwwroot/assets/book.epub",
+                    UserId = userId,
+                    Author = author,
+                    TenantId = "global"
+                };
+                context.Ebooks.Add(ebook);
+                await context.SaveChangesAsync();
+            }
+
+            return Result.Ok(new ReaderPageViewModel(blocks, chapterIndex, readingOrder.Count, chapterTitle, ebook?.Id ?? Guid.Empty));
         }
         catch (Exception ex)
         {

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

@@ -11,6 +11,8 @@
 @inject KnowledgeCoordinator Coordinator
 @inject IReaderInteractionService InteractionService
 @inject ISyncService SyncService
+@using Microsoft.AspNetCore.Components.Authorization
+@inject AuthenticationStateProvider AuthStateProvider
 
 <div class="reader-canvas @(ThemeService.IsLightMode ? "theme-light" : "theme-dark")">
     @if (ViewModel == null)
@@ -190,7 +192,10 @@
         ViewModel = null;
         StatusMessage = "Fetching content...";
         
-        var result = await Mediator.Send(new GetReaderPageQuery(index));
+        var authState = await AuthStateProvider.GetAuthenticationStateAsync();
+        var userId = authState.User.FindFirst(System.Security.Claims.ClaimTypes.NameIdentifier)?.Value;
+
+        var result = await Mediator.Send(new GetReaderPageQuery(index, userId));
         if (result.IsSuccess)
         {
             ViewModel = result.Value;

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

@@ -14,7 +14,7 @@ public class WasmEpubService : IEpubService
         _httpClient = httpClient;
     }
 
-    public async Task<Result<ReaderPageViewModel>> GetEpubContentAsync(int chapterIndex)
+    public async Task<Result<ReaderPageViewModel>> GetEpubContentAsync(int chapterIndex, string? userId = null)
     {
         try
         {

src/NexusReader.Web.New/Program.cs

@@ -226,9 +226,11 @@ app.MapStaticAssets();
 app.MapHub<NexusReader.Infrastructure.RealTime.SyncHub>("/synchub");
 
 // API endpoint for WASM client to fetch EPUB content
-app.MapGet("/api/epub/{index}", async (int index, IEpubService epubService) =>
+app.MapGet("/api/epub/{index}", async (int index, IEpubService epubService, ClaimsPrincipal user) =>
 {
-    var result = await epubService.GetEpubContentAsync(index);
+    var userId = user.FindFirstValue(ClaimTypes.NameIdentifier);
+    var result = await epubService.GetEpubContentAsync(index, userId);
+    
     if (result.IsSuccess) return Results.Ok(result.Value);
     
     var errorMsg = result.Errors.Count > 0 ? result.Errors[0].Message : "Unknown server error";