refactor: address PR review comments for ingestion workflow

src/NexusReader.Application/Commands/Library/IngestEbookCommandHandler.cs

@@ -23,18 +23,30 @@ public class IngestEbookCommandHandler : IRequestHandler<IngestEbookCommand, Res
 
     public async Task<Result<Guid>> Handle(IngestEbookCommand request, CancellationToken cancellationToken)
     {
+        using var context = await _dbContextFactory.CreateDbContextAsync(cancellationToken);
+        
+        string epubPath;
+        string? coverUrl;
+
         try
         {
-            using var context = await _dbContextFactory.CreateDbContextAsync(cancellationToken);
-
             // 1. Save Files
-            var epubPath = await _storageService.SaveEbookAsync(request.EpubData, $"{request.Title}.epub");
-            var coverUrl = request.CoverImage != null && request.CoverImage.Length > 0
+            epubPath = await _storageService.SaveEbookAsync(request.EpubData, $"{request.Title}.epub");
+            coverUrl = request.CoverImage != null && request.CoverImage.Length > 0
                 ? await _storageService.SaveCoverAsync(request.CoverImage, $"{request.Title}_cover.jpg")
                 : null;
+        }
+        catch (Exception ex)
+        {
+            return Result.Fail(new Error($"Storage failure: {ex.Message}").CausedBy(ex));
+        }
 
+        try
+        {
             // 2. Resolve Author
             var authorName = string.IsNullOrWhiteSpace(request.AuthorName) ? "Unknown Author" : request.AuthorName.Trim();
+            
+            // Use case-insensitive comparison
             var author = await context.Authors
                 .FirstOrDefaultAsync(a => a.Name.ToLower() == authorName.ToLower(), cancellationToken);
 
@@ -42,8 +54,6 @@ public class IngestEbookCommandHandler : IRequestHandler<IngestEbookCommand, Res
             {
                 author = new Author { Name = authorName };
                 context.Authors.Add(author);
-                // We need to save to get the Author ID if we want to use it, 
-                // but EF will handle it if we assign the object.
             }
 
             // 3. Create Ebook
@@ -51,7 +61,7 @@ public class IngestEbookCommandHandler : IRequestHandler<IngestEbookCommand, Res
             {
                 Title = request.Title,
                 Author = author,
-                FilePath = epubPath,
+                FilePath = epubPath, // Relative URL from wwwroot
                 CoverUrl = coverUrl,
                 UserId = request.UserId,
                 TenantId = request.TenantId,
@@ -63,9 +73,13 @@ public class IngestEbookCommandHandler : IRequestHandler<IngestEbookCommand, Res
 
             return Result.Ok(ebook.Id);
         }
+        catch (DbUpdateException ex)
+        {
+            return Result.Fail(new Error($"Database error during ingestion: {ex.Message}").CausedBy(ex));
+        }
         catch (Exception ex)
         {
-            return Result.Fail(new Error("Failed to ingest ebook").CausedBy(ex));
+            return Result.Fail(new Error($"Unexpected error during ingestion: {ex.Message}").CausedBy(ex));
         }
     }
 }