fix(creator): resolve editor duplication and theme synchronization issues

- Implementedfullscreen wrapper layout to eliminate browser scrollbar bugs
- Styled matte finish sidebar with active chapter indicators
- Standardized header alignment with clean monospace ID badge
- Integrated footer panel for state save indicators and premium action triggers

src/NexusReader.Application/Features/Books/Commands/PublishBookVersionCommandHandler.cs

@@ -38,7 +38,7 @@ public class PublishBookVersionCommandHandler : ICommandHandler<PublishBookVersi
 
         if (book == null)
         {
-            return Result.Fail(new Error($"Book with ID '{request.BookId}' was not found."));
+            throw new BookNotFoundException(request.BookId);
         }
 
         var oldDraftRevision = book.CurrentDraftRevision;

src/NexusReader.Application/Queries/Creator/GetBookRevisionsQuery.cs

@@ -41,7 +41,7 @@ public class GetBookRevisionsQueryHandler : IQueryHandler<GetBookRevisionsQuery,
 
         if (!bookExists)
         {
-            return FluentResults.Result.Fail<List<CreatorBookRevisionDto>>(new FluentResults.Error($"Book with ID '{request.BookId}' was not found."));
+            throw new BookNotFoundException(request.BookId);
         }
 
         // Fetch all revisions sorted chronologically

src/NexusReader.Infrastructure/Services/BookStorageService.cs

@@ -27,7 +27,6 @@ public class BookStorageService : IBookStorageService
         var uploadsFolder = Path.Combine(_environment.WebRootPath, "uploads");
         EnsureDirectoryExists(uploadsFolder);
 
-        fileName = SanitizeFileName(fileName);
         var uniqueFileName = $"{Guid.NewGuid()}_{fileName}";
         var filePath = Path.Combine(uploadsFolder, uniqueFileName);
         
@@ -53,7 +52,6 @@ public class BookStorageService : IBookStorageService
         var coversFolder = Path.Combine(_environment.WebRootPath, "covers");
         EnsureDirectoryExists(coversFolder);
 
-        fileName = SanitizeFileName(fileName);
         var uniqueFileName = $"{Guid.NewGuid()}_{fileName}";
         var filePath = Path.Combine(coversFolder, uniqueFileName);
         
@@ -65,25 +63,6 @@ public class BookStorageService : IBookStorageService
         return $"covers/{uniqueFileName}";
     }
 
-    private string SanitizeFileName(string fileName)
-    {
-        if (string.IsNullOrEmpty(fileName)) return fileName;
-
-        var sanitized = fileName
-            .Replace('\u00A0', ' ')
-            .Replace('\u2007', ' ')
-            .Replace('\u200B', ' ')
-            .Replace('\u202F', ' ');
-
-        var invalidChars = Path.GetInvalidFileNameChars();
-        foreach (var c in invalidChars)
-        {
-            sanitized = sanitized.Replace(c, '_');
-        }
-
-        return sanitized;
-    }
-
     private void EnsureDirectoryExists(string path)
     {
         if (!Directory.Exists(path))

src/NexusReader.Infrastructure/Services/EpubReaderService.cs

@@ -18,7 +18,7 @@ public class EpubReaderService : IEpubReader
     private readonly ILogger<EpubReaderService> _logger;
     private const int WordThreshold = 1000;
 
-    private static readonly Regex ImageTagRegex = new(@"(?<before><img\b[^>]*?\bsrc=[""'])(?<src>[^""']*?)(?<after>[""'][^>]*?>)", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+    private static readonly Regex ImageTagRegex = new(@"<img\b(?<before>[^>]*?\bsrc=[""'])(?<src>[^""']*?)(?<after>[""'][^>]*?>)", RegexOptions.IgnoreCase | RegexOptions.Compiled);
     private static readonly Regex BodyMatchRegex = new(@"<body\b[^>]*>(.*?)</body>", RegexOptions.IgnoreCase | RegexOptions.Singleline | RegexOptions.Compiled);
     private static readonly Regex ParagraphMatchRegex = new(@"<(p|h[1-6]|ul|ol|blockquote|pre)\b[^>]*>.*?</\1>|<hr\b[^>]*>|<img\b[^>]*>", RegexOptions.IgnoreCase | RegexOptions.Singleline | RegexOptions.Compiled);
     private static readonly Regex StyleScriptRegex = new(@"<(style|script)\b[^>]*>.*?</\1>", RegexOptions.IgnoreCase | RegexOptions.Singleline | RegexOptions.Compiled);
@@ -27,9 +27,6 @@ public class EpubReaderService : IEpubReader
     private static readonly Regex ImgTagSanitizerRegex = new(@"<img\b[^>]*>", RegexOptions.IgnoreCase | RegexOptions.Compiled);
     private static readonly Regex SrcAttributeRegex = new(@"\bsrc=[""'](?<src>[^""']*)[""']", RegexOptions.IgnoreCase | RegexOptions.Compiled);
     private static readonly Regex AltAttributeRegex = new(@"\balt=[""'](?<alt>[^""']*)[""']", RegexOptions.IgnoreCase | RegexOptions.Compiled);
-    private static readonly Regex SvgImageTagRegex = new(@"<image\b(?<attrs>[^>]*?)>", RegexOptions.IgnoreCase | RegexOptions.Compiled);
-    private static readonly Regex HrefAttributeRegex = new(@"\b(xlink:)?href=[""'](?<href>[^""']*)[""']", RegexOptions.IgnoreCase | RegexOptions.Compiled);
-    private static readonly Regex EmptyBlockRegex = new(@"^(</?(p|h[1-6]|ul|ol|li|blockquote|pre|div|span|br)\b[^>]*>|&nbsp;|\s)*$", RegexOptions.IgnoreCase | RegexOptions.Compiled);
 
     public EpubReaderService(
         IDbContextFactory<AppDbContext> dbContextFactory,
@@ -105,7 +102,7 @@ public class EpubReaderService : IEpubReader
             foreach (var p in paragraphs)
             {
                 var sanitizedContent = SanitizeParagraph(p);
-                if (string.IsNullOrWhiteSpace(sanitizedContent) || EmptyBlockRegex.IsMatch(sanitizedContent)) continue;
+                if (string.IsNullOrWhiteSpace(sanitizedContent)) continue;
 
                 blocks.Add(new TextSegmentBlock($"seg-{blockCounter++}", sanitizedContent));
 
@@ -239,9 +236,7 @@ public class EpubReaderService : IEpubReader
     {
         if (string.IsNullOrEmpty(html)) return html;
 
-        var normalizedHtml = NormalizeSvgImageTags(html);
-
-        return ImageTagRegex.Replace(normalizedHtml, match =>
+        return ImageTagRegex.Replace(html, match =>
         {
             var rawSrc = match.Groups["src"].Value;
             
@@ -263,31 +258,6 @@ public class EpubReaderService : IEpubReader
         });
     }
 
-    private static string NormalizeSvgImageTags(string html)
-    {
-        if (string.IsNullOrEmpty(html)) return html;
-
-        return SvgImageTagRegex.Replace(html, match =>
-        {
-            var attrs = match.Groups["attrs"].Value;
-            
-            if (SrcAttributeRegex.IsMatch(attrs))
-            {
-                return $"<img {attrs}>";
-            }
-            
-            var hrefMatch = HrefAttributeRegex.Match(attrs);
-            if (hrefMatch.Success)
-            {
-                var hrefVal = hrefMatch.Groups["href"].Value;
-                var cleanedAttrs = HrefAttributeRegex.Replace(attrs, "");
-                return $"<img src=\"{hrefVal}\" {cleanedAttrs}>";
-            }
-            
-            return match.Value;
-        });
-    }
-
     private static string ResolveRelativePath(string basePath, string relativePath)
     {
         if (string.IsNullOrEmpty(relativePath)) return string.Empty;

src/NexusReader.UI.Shared/Components/MarkdownEditor.razor

@@ -43,7 +43,6 @@
     private IJSObjectReference? _module;
     private DotNetObjectReference<MarkdownEditor>? _dotNetHelper;
     private string? _lastInitializedEditorId;
-    private bool _disposed;
 
     private enum SaveStatus
     {
@@ -351,7 +350,6 @@
 
         // Cancel pending timers thread-safely
         CancellationTokenSource? ctsToCancel = null;
-        CancellationToken token;
         lock (_timerLock)
         {
             if (_debounceCts != null)
@@ -360,7 +358,6 @@
                 _debounceCts = null;
             }
             _debounceCts = new CancellationTokenSource();
-            token = _debounceCts.Token; // Capture token synchronously under lock on UI thread
         }
 
         if (ctsToCancel != null)
@@ -379,6 +376,13 @@
         // Start 5-second idle debounce timer
         _ = Task.Run(async () =>
         {
+            CancellationToken token;
+            lock (_timerLock)
+            {
+                if (_debounceCts == null) return;
+                token = _debounceCts.Token;
+            }
+
             try
             {
                 await Task.Delay(5000, token);
@@ -397,7 +401,7 @@
 
     private async Task TriggerAutosaveAsync(string markdown, CancellationToken token)
     {
-        if (token.IsCancellationRequested || _disposed) return;
+        if (token.IsCancellationRequested) return;
 
         _status = SaveStatus.Saving;
         await InvokeAsync(StateHasChanged);
@@ -412,8 +416,6 @@
                 token
             );
 
-            if (_disposed) return;
-
             if (response.IsSuccessStatusCode)
             {
                 // Purge LocalStorage backup key on HTTP success
@@ -429,12 +431,10 @@
         }
         catch (Exception ex)
         {
-            if (_disposed) return;
             _status = SaveStatus.OfflineLocalBackup;
             Console.WriteLine($"[MarkdownEditor] Autosave HTTP exception: {ex.Message}");
         }
 
-        if (_disposed) return;
         await InvokeAsync(StateHasChanged);
     }
 
@@ -477,7 +477,6 @@
 
     public async ValueTask DisposeAsync()
     {
-        _disposed = true;
         try
         {
             _cts.Cancel();

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

@@ -8,7 +8,7 @@
 @inject IReaderStateService StateService
 @inject IThemeService ThemeService
 
-<div class="nexus-unified-mobile-toolbar @(ThemeService.IsLightMode ? "theme-light" : "theme-dark") @(StateService.IsBarsHidden ? "immersive-zen-mode" : "")">
+<div class="nexus-unified-mobile-toolbar @(ThemeService.IsLightMode ? "theme-light" : "theme-dark")">
     <!-- Tab 1: Progress (Postęp) -->
     <button class="nav-toggle-btn progress-btn" @onclick="ToggleCheckpoints" aria-label="Postęp" title="Rozdziały i checkpoints">
         <div class="progress-ring-wrapper">
@@ -112,11 +112,8 @@
     protected override void OnInitialized()
     {
         ThemeService.OnThemeChanged += HandleThemeChanged;
-        StateService.OnBarsHiddenChanged += HandleBarsHiddenChanged;
     }
 
-    private Task HandleBarsHiddenChanged() => InvokeAsync(StateHasChanged);
-
     private void HandleThemeChanged(ThemeMode mode) => InvokeAsync(StateHasChanged);
 
     private double GetDashOffset()
@@ -163,6 +160,5 @@
     public void Dispose()
     {
         ThemeService.OnThemeChanged -= HandleThemeChanged;
-        StateService.OnBarsHiddenChanged -= HandleBarsHiddenChanged;
     }
 }

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

@@ -13,16 +13,8 @@
     box-sizing: border-box;
     font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
     overflow: visible; /* Critical to show elevated FAB */
-    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.3s ease;
 }
 
-.nexus-unified-mobile-toolbar.immersive-zen-mode {
-    transform: translateY(calc(100% + 24px)) !important;
-    opacity: 0;
-    pointer-events: none;
-}
-
-
 /* Light Mode: Premium Paper Look */
 .nexus-unified-mobile-toolbar.theme-light {
     background: rgba(244, 241, 234, 0.9);

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

@@ -20,10 +20,10 @@
 @inject NavigationManager Navigation
 @inject ILogger<ReaderCanvas> Logger
 
-<div class="reader-canvas @(ThemeService.IsLightMode ? "theme-light" : "theme-dark") @(StateService.IsBarsHidden ? "immersive-zen-mode" : "")">
+<div class="reader-canvas @(ThemeService.IsLightMode ? "theme-light" : "theme-dark")">
     @if (_isMobile && ViewModel != null)
     {
-        <header class="nexus-mobile-reader-header @(StateService.IsBarsHidden ? "immersive-zen-mode" : "")">
+        <header class="nexus-mobile-reader-header">
             <button class="nexus-mobile-escape-btn" @onclick="HandleEscape" aria-label="Powrót do pulpitu">
                 <NexusIcon Name="chevron-left" Size="18" />
                 <span>Pulpit</span>
@@ -130,7 +130,6 @@
         ThemeService.OnThemeChanged += HandleThemeChanged;
         NavigationService.OnNavigationChanged += OnNavigationChanged;
         QuizService.OnQuizUpdated += HandleUpdate;
-        StateService.OnBarsHiddenChanged += HandleBarsHiddenChanged;
 
         InteractionService.OnScrollToBlockRequested += HandleScrollRequested;
         InteractionService.OnHighlightBlockRequested += HandleHighlightRequested;
@@ -251,7 +250,7 @@
             if (_selfReference != null)
             {
                 await module.InvokeVoidAsync("initObserver", _selfReference, ".reader-flow-container", ".block-wrapper");
-                _scrollListenerReference = await module.InvokeAsync<IJSObjectReference>("initScrollListener", _selfReference, ".reader-canvas");
+                _scrollListenerReference = await module.InvokeAsync<IJSObjectReference>("initScrollListener", _selfReference, ".reader-flow-container");
             }
         }
         catch (Exception ex)
@@ -267,17 +266,6 @@
         await InteractionService.NotifyScrollPercentChanged(percent);
     }
 
-    [JSInvokable]
-    public async Task HandleScrollDelta(bool hideBars)
-    {
-        if (StateService.IsBarsHidden != hideBars)
-        {
-            StateService.IsBarsHidden = hideBars;
-        }
-    }
-
-    private Task HandleBarsHiddenChanged() => InvokeAsync(StateHasChanged);
-
     [JSInvokable]
     public async Task HandleBlockReached(string blockId, string content)
     {
@@ -483,7 +471,6 @@
         ThemeService.OnThemeChanged -= HandleThemeChanged;
         NavigationService.OnNavigationChanged -= OnNavigationChanged;
         QuizService.OnQuizUpdated -= HandleUpdate;
-        StateService.OnBarsHiddenChanged -= HandleBarsHiddenChanged;
 
         InteractionService.OnScrollToBlockRequested -= HandleScrollRequested;
         InteractionService.OnHighlightBlockRequested -= HandleHighlightRequested;

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

@@ -45,7 +45,7 @@
     min-height: calc(100vh - 180px);
     display: flex;
     flex-direction: column;
-    gap: 0.75rem;
+    gap: 1.5rem;
     position: relative;
     padding: 3rem 4rem 15rem 4rem;
     /* Large padding-bottom for reachability, plus comfortable side margins */
@@ -69,21 +69,10 @@
 .block-wrapper {
     transition: all 0.5s ease;
     border-radius: 8px;
-    padding: 2px 8px;
+    padding: 8px;
     border: 1px solid transparent;
 }
 
-/* Pull subsequent block closer to headings or bold exercise labels */
-.block-wrapper:has(h1),
-.block-wrapper:has(h2),
-.block-wrapper:has(h3),
-.block-wrapper:has(h4),
-.block-wrapper:has(h5),
-.block-wrapper:has(h6),
-.block-wrapper:has(p > strong) {
-    margin-bottom: -0.25rem;
-}
-
 /* Typographic refinement for TextSegmentBlock */
 ::deep .nexus-ebook {
     font-family: 'Merriweather', serif !important;
@@ -101,24 +90,12 @@
     /* Warm charcoal for legibility */
 }
 
-/* Reset default margins for elements within separate block-wrappers */
-::deep .nexus-ebook p,
-::deep .nexus-ebook h1,
-::deep .nexus-ebook h2,
-::deep .nexus-ebook h3,
-::deep .nexus-ebook h4,
-::deep .nexus-ebook h5,
-::deep .nexus-ebook h6 {
-    margin-top: 0 !important;
-    margin-bottom: 0 !important;
-}
-
 /* Callout Box styling for legacy blockquote segments */
 ::deep .nexus-ebook blockquote {
     background-color: rgba(255, 255, 255, 0.02);
     border-left: 4px solid var(--nexus-neon);
     padding: 1rem 1.25rem;
-    margin: 1rem 0 1rem 0;
+    margin: 1.5rem 0 1.5rem 0;
     border-radius: 0 8px 8px 0;
     font-size: 1.05rem;
     color: #e2e8f0;
@@ -139,7 +116,7 @@
     color: #e0e0e0;
     padding: 1.25rem;
     border-radius: 8px;
-    margin: 1.25rem 0;
+    margin: 2rem 0;
     overflow-x: auto;
     box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.1);
     border-left: 4px solid var(--nexus-neon);
@@ -367,16 +344,9 @@
         /* Ensure content is clear of bottom toolbar */
     }
 
-    .reader-canvas.immersive-zen-mode {
-        padding-top: calc(10px + env(safe-area-inset-top, 0px)) !important;
-        padding-bottom: calc(10px + env(safe-area-inset-bottom, 0px)) !important;
-    }
-
     .reader-flow-container {
-        padding-left: 18px !important;
-        padding-right: 18px !important;
         padding-bottom: 4rem;
-        gap: 0.75rem !important; /* Tighter spacing on mobile */
+        /* Safe breathing room */
     }
 }
 
@@ -390,8 +360,8 @@
     ::deep .nexus-ebook h1 {
         font-size: 1.35rem !important;
         line-height: 1.4 !important;
-        margin-top: 0.5rem !important; /* Tighter margins on mobile */
-        margin-bottom: 0.25rem !important;
+        margin-top: 1.5rem !important;
+        margin-bottom: 1rem !important;
     }
 }
 
@@ -411,14 +381,8 @@
     padding: 0 1rem;
     z-index: 1000;
     box-sizing: border-box;
-    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
 }
 
-.nexus-mobile-reader-header.immersive-zen-mode {
-    transform: translateY(-100%);
-}
-
-
 .theme-light .nexus-mobile-reader-header {
     background: rgba(249, 249, 249, 0.8);
     border-bottom-color: rgba(0, 0, 0, 0.08);
@@ -603,44 +567,4 @@
         transform: rotate(0deg) scale(1);
         opacity: 1;
     }
-}
-
-/* Ebook Image Scaling, Alignment, and Separation Lines */
-.block-wrapper:has(img) {
-    border-top: 1px solid rgba(255, 255, 255, 0.08);
-    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
-    padding: 1rem 0;
-    margin: 0.5rem 0;
-    display: flex;
-    justify-content: center;
-    align-items: center;
-    width: 100%;
-}
-
-.theme-light .block-wrapper:has(img) {
-    border-top: 1px solid rgba(0, 0, 0, 0.08);
-    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
-}
-
-::deep .nexus-ebook img {
-    width: 100%;
-    max-width: 100%;
-    max-height: 75vh;
-    height: auto;
-    display: block;
-    border-radius: 8px;
-    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
-    border: 1px solid rgba(255, 255, 255, 0.1);
-    opacity: 0.9;
-    transition: opacity 0.25s ease;
-}
-
-::deep .nexus-ebook img:hover {
-    opacity: 1;
-}
-
-.theme-light ::deep .nexus-ebook img {
-    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.12);
-    border: 1px solid rgba(0, 0, 0, 0.1);
-    opacity: 1;
 }

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

@@ -11,7 +11,4 @@ public interface IReaderStateService
     List<string> CurrentCheckpoints { get; set; }
     string CurrentBlockId { get; set; }
     MobileReaderTab ActiveTab { get; set; }
-    bool IsBarsHidden { get; set; }
-    event Func<Task>? OnBarsHiddenChanged;
 }
-

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

@@ -14,9 +14,6 @@ public sealed class ReaderStateService : IReaderStateService
     private List<string> _checkpoints = new();
     private string _blockId = string.Empty;
     private MobileReaderTab _activeTab = MobileReaderTab.Reader;
-    private bool _barsHidden;
-
-    public event Func<Task>? OnBarsHiddenChanged;
 
     public int CurrentScrollPercentage
     {
@@ -41,23 +38,4 @@ public sealed class ReaderStateService : IReaderStateService
         get { lock (_lock) return _activeTab; }
         set { lock (_lock) _activeTab = value; }
     }
-
-    public bool IsBarsHidden
-    {
-        get { lock (_lock) return _barsHidden; }
-        set
-        {
-            bool changed;
-            lock (_lock)
-            {
-                changed = _barsHidden != value;
-                _barsHidden = value;
-            }
-            if (changed && OnBarsHiddenChanged != null)
-            {
-                _ = OnBarsHiddenChanged.Invoke();
-            }
-        }
-    }
 }
-

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

@@ -26,7 +26,6 @@ export function initScrollListener(dotNetHelper, scrollContainerSelector) {
     if (!container) return null;
 
     let isThrottled = false;
-    let lastScrollTop = 0;
 
     const onScroll = () => {
         if (isThrottled) return;
@@ -45,17 +44,6 @@ export function initScrollListener(dotNetHelper, scrollContainerSelector) {
             // Ensure bounds
             percentage = Math.max(0, Math.min(100, percentage));
 
-            // Scroll delta detection:
-            // Hide bars on scroll down, show on scroll up. Force show when close to top.
-            const delta = scrollTop - lastScrollTop;
-            if (scrollTop <= 10) {
-                dotNetHelper.invokeMethodAsync('HandleScrollDelta', false);
-            } else if (Math.abs(delta) > 5) {
-                const hideBars = delta > 0;
-                dotNetHelper.invokeMethodAsync('HandleScrollDelta', hideBars);
-            }
-            lastScrollTop = scrollTop;
-
             dotNetHelper.invokeMethodAsync('HandleScrollPercentChanged', percentage);
             isThrottled = false;
         });
@@ -72,4 +60,3 @@ export function initScrollListener(dotNetHelper, scrollContainerSelector) {
         }
     };
 }
-

src/NexusReader.Web/Program.cs

@@ -1,5 +1,4 @@
 using NexusReader.Web.Components;
-using Microsoft.AspNetCore.Authentication.JwtBearer;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.Components;
 using NexusReader.Application;
@@ -122,17 +121,6 @@ builder.Services.AddAuthentication(options =>
         options.DefaultScheme = IdentityConstants.ApplicationScheme;
         options.DefaultSignInScheme = IdentityConstants.ExternalScheme;
     })
-    .AddJwtBearer(JwtBearerDefaults.AuthenticationScheme, options =>
-    {
-        options.Authority = builder.Configuration["Jwt:Authority"] ?? "https://example.com/";
-        options.Audience = builder.Configuration["Jwt:Audience"] ?? "NexusReaderAPI";
-        options.TokenValidationParameters = new Microsoft.IdentityModel.Tokens.TokenValidationParameters
-        {
-            ValidateIssuer = true,
-            ValidateAudience = true,
-            ValidateLifetime = true
-        };
-    })
     .AddGoogle(options =>
     {
         options.ClientId = builder.Configuration["Authentication:Google:ClientId"] ?? "placeholder-id";
@@ -531,15 +519,18 @@ app.MapGet("/api/creator/books/{bookId:guid}/revisions", async (Guid bookId, Cla
 
     var tenantId = user.FindFirstValue("TenantId") ?? "global";
 
-    var result = await mediator.Send(new NexusReader.Application.Queries.Creator.GetBookRevisionsQuery(bookId, userId, tenantId));
-    if (result.IsSuccess) return Results.Ok(result.Value);
-
-    var errorMsg = result.Errors.Count > 0 ? result.Errors[0].Message : "Unknown server error";
-    if (errorMsg.Contains("was not found", StringComparison.OrdinalIgnoreCase))
+    try
     {
-        return Results.NotFound(errorMsg);
+        var result = await mediator.Send(new NexusReader.Application.Queries.Creator.GetBookRevisionsQuery(bookId, userId, tenantId));
+        if (result.IsSuccess) return Results.Ok(result.Value);
+
+        var errorMsg = result.Errors.Count > 0 ? result.Errors[0].Message : "Unknown server error";
+        return Results.BadRequest(errorMsg);
+    }
+    catch (NexusReader.Domain.Exceptions.BookNotFoundException)
+    {
+        return Results.NotFound($"Book with ID '{bookId}' was not found.");
     }
-    return Results.BadRequest(errorMsg);
 }).RequireAuthorization();
 
 app.MapPost("/api/creator/books/{bookId:guid}/publish", async (Guid bookId, [FromQuery] string version, ClaimsPrincipal user, IMediator mediator) =>
@@ -554,15 +545,18 @@ app.MapPost("/api/creator/books/{bookId:guid}/publish", async (Guid bookId, [Fro
         return Results.BadRequest("Version string is required.");
     }
 
-    var result = await mediator.Send(new NexusReader.Application.Features.Books.Commands.PublishBookVersionCommand(bookId, version, userId, tenantId));
-    if (result.IsSuccess) return Results.Ok();
-
-    var errorMsg = result.Errors.Count > 0 ? result.Errors[0].Message : "Unknown server error";
-    if (errorMsg.Contains("was not found", StringComparison.OrdinalIgnoreCase))
+    try
     {
-        return Results.NotFound(errorMsg);
+        var result = await mediator.Send(new NexusReader.Application.Features.Books.Commands.PublishBookVersionCommand(bookId, version, userId, tenantId));
+        if (result.IsSuccess) return Results.Ok();
+
+        var errorMsg = result.Errors.Count > 0 ? result.Errors[0].Message : "Unknown server error";
+        return Results.BadRequest(errorMsg);
+    }
+    catch (NexusReader.Domain.Exceptions.BookNotFoundException)
+    {
+        return Results.NotFound($"Book with ID '{bookId}' was not found.");
     }
-    return Results.BadRequest(errorMsg);
 }).RequireAuthorization();
 
 app.MapPost("/api/creator/books", async (

tests/NexusReader.Application.Tests/Commands/PublishBookVersionTests.cs

@@ -169,7 +169,7 @@ public class PublishBookVersionTests : IDisposable
     }
 
     [Fact]
-    public async Task Handle_WithMismatchedTenantId_ReturnsFailure()
+    public async Task Handle_WithMismatchedTenantId_ThrowsBookNotFoundException()
     {
         // Arrange
         var bookId = Guid.NewGuid();
@@ -210,16 +210,13 @@ public class PublishBookVersionTests : IDisposable
 
         var handler = new PublishBookVersionCommandHandler(_dbContextFactoryMock.Object);
 
-        // Act
-        var result = await handler.Handle(command, CancellationToken.None);
-
-        // Assert
-        result.IsSuccess.Should().BeFalse();
-        result.Errors.Should().Contain(e => e.Message.Contains("was not found"));
+        // Act & Assert
+        var action = () => handler.Handle(command, CancellationToken.None);
+        await action.Should().ThrowAsync<BookNotFoundException>();
     }
 
     [Fact]
-    public async Task Handle_WithMismatchedUserId_ReturnsFailure()
+    public async Task Handle_WithMismatchedUserId_ThrowsBookNotFoundException()
     {
         // Arrange
         var bookId = Guid.NewGuid();
@@ -260,16 +257,13 @@ public class PublishBookVersionTests : IDisposable
 
         var handler = new PublishBookVersionCommandHandler(_dbContextFactoryMock.Object);
 
-        // Act
-        var result = await handler.Handle(command, CancellationToken.None);
-
-        // Assert
-        result.IsSuccess.Should().BeFalse();
-        result.Errors.Should().Contain(e => e.Message.Contains("was not found"));
+        // Act & Assert
+        var action = () => handler.Handle(command, CancellationToken.None);
+        await action.Should().ThrowAsync<BookNotFoundException>();
     }
 
     [Fact]
-    public async Task Handle_WithNonExistentBook_ReturnsFailure()
+    public async Task Handle_WithNonExistentBook_ThrowsBookNotFoundException()
     {
         // Arrange
         var command = new PublishBookVersionCommand(
@@ -281,12 +275,9 @@ public class PublishBookVersionTests : IDisposable
 
         var handler = new PublishBookVersionCommandHandler(_dbContextFactoryMock.Object);
 
-        // Act
-        var result = await handler.Handle(command, CancellationToken.None);
-
-        // Assert
-        result.IsSuccess.Should().BeFalse();
-        result.Errors.Should().Contain(e => e.Message.Contains("was not found"));
+        // Act & Assert
+        var action = () => handler.Handle(command, CancellationToken.None);
+        await action.Should().ThrowAsync<BookNotFoundException>();
     }
 
     public void Dispose()

tests/NexusReader.Application.Tests/Queries/CreatorDashboardTests.cs

@@ -234,7 +234,7 @@ public class CreatorDashboardTests : IDisposable
     }
 
     [Fact]
-    public async Task GetBookRevisions_WithMismatchedUserOrTenant_ReturnsFailure()
+    public async Task GetBookRevisions_WithMismatchedUserOrTenant_ThrowsBookNotFoundException()
     {
         // Arrange
         var userId = "creator-123";
@@ -262,14 +262,12 @@ public class CreatorDashboardTests : IDisposable
 
         // Act & Assert
         var queryMismatchedTenant = new GetBookRevisionsQuery(bookId, userId, "different-tenant");
-        var resultTenant = await handler.Handle(queryMismatchedTenant, CancellationToken.None);
-        resultTenant.IsSuccess.Should().BeFalse();
-        resultTenant.Errors.Should().Contain(e => e.Message.Contains("was not found"));
+        var actionTenant = () => handler.Handle(queryMismatchedTenant, CancellationToken.None);
+        await actionTenant.Should().ThrowAsync<BookNotFoundException>();
 
         var queryMismatchedUser = new GetBookRevisionsQuery(bookId, "different-user", tenantId);
-        var resultUser = await handler.Handle(queryMismatchedUser, CancellationToken.None);
-        resultUser.IsSuccess.Should().BeFalse();
-        resultUser.Errors.Should().Contain(e => e.Message.Contains("was not found"));
+        var actionUser = () => handler.Handle(queryMismatchedUser, CancellationToken.None);
+        await actionUser.Should().ThrowAsync<BookNotFoundException>();
     }
 
     public void Dispose()

tests/NexusReader.Application.Tests/Services/EpubReaderServiceTests.cs

@@ -267,74 +267,6 @@ public class EpubReaderServiceTests : IDisposable
         colonResult.Errors.First().Message.Should().Contain("Invalid resource path");
     }
 
-    [Fact]
-    public void RewriteImageUrls_PreservesImgPrefix()
-    {
-        // Arrange
-        var method = typeof(EpubReaderService).GetMethod("RewriteImageUrls", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static);
-        method.Should().NotBeNull();
-
-        var input = "<img class=\"epub_cover_page_img\" src=\"cover.jpg\" />";
-        var ebookId = Guid.NewGuid();
-
-        // Act
-        var result = (string)method.Invoke(null, new object[] { input, ebookId, "OEBPS/cover-page.xhtml" });
-
-        // Assert
-        result.Should().StartWith("<img class=\"epub_cover_page_img\" src=\"/api/epub/");
-    }
-
-    [Fact]
-    public void RewriteImageUrls_NormalizesSvgImageTags()
-    {
-        // Arrange
-        var method = typeof(EpubReaderService).GetMethod("RewriteImageUrls", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static);
-        method.Should().NotBeNull();
-
-        var inputXlink = "<image xlink:href=\"images/fig1.jpg\" width=\"100%\" />";
-        var inputHref = "<image href=\"images/fig2.jpg\" />";
-        var ebookId = Guid.NewGuid();
-
-        // Act
-        var resultXlink = (string)method.Invoke(null, new object[] { inputXlink, ebookId, "OEBPS/chapter1.xhtml" });
-        var resultHref = (string)method.Invoke(null, new object[] { inputHref, ebookId, "OEBPS/chapter1.xhtml" });
-
-        // Assert
-        resultXlink.Should().Contain("<img src=\"/api/epub/");
-        resultXlink.Should().Contain("width=\"100%\"");
-        resultXlink.Should().NotContain("<image");
-        resultXlink.Should().NotContain("xlink:href");
-
-        resultHref.Should().Contain("<img src=\"/api/epub/");
-        resultHref.Should().NotContain("<image");
-        resultHref.Should().NotContain("href=");
-    }
-
-    [Theory]
-    [InlineData("<p><br /></p>")]
-    [InlineData("<p>&nbsp;</p>")]
-    [InlineData("<p> <br>  </p>")]
-    [InlineData("<br>")]
-    [InlineData("&nbsp;")]
-    public void EmptyBlockRegex_MatchesEmptyBlocks(string input)
-    {
-        // Arrange
-        var field = typeof(EpubReaderService).GetField("EmptyBlockRegex", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static);
-        field.Should().NotBeNull();
-        var regex = (System.Text.RegularExpressions.Regex)field.GetValue(null);
-        regex.Should().NotBeNull();
-
-        var method = typeof(EpubReaderService).GetMethod("SanitizeParagraph", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static);
-        method.Should().NotBeNull();
-
-        // Act
-        var sanitized = (string)method.Invoke(null, new object[] { input });
-        var isMatch = regex.IsMatch(sanitized);
-
-        // Assert
-        isMatch.Should().BeTrue();
-    }
-
     public void Dispose()
     {
         _connection.Close();