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

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)
         {