diff --git a/PlotLine/Services/OnboardingService.cs b/PlotLine/Services/OnboardingService.cs
index 53fdfdd..92fd24c 100644
--- a/PlotLine/Services/OnboardingService.cs
+++ b/PlotLine/Services/OnboardingService.cs
@@ -247,7 +247,7 @@ public sealed class OnboardingService(
 
         await PublishBuildProgress(userId, preview.PreviewID, "Creating characters...", 60, progress);
         var result = await builds.BuildAsync(userId, request)
-            ?? throw new InvalidOperationException("The project structure could not be built. Check the review choices and try again.");
+            ?? throw new InvalidOperationException($"The project structure could not be built. Approved chapters: {request.Chapters.Count}, scenes: {request.Scenes.Count}, characters: {request.Characters.Count}. Return to review, save your selections, and try Build Project again.");
         await scanPreviews.SaveBuildResultAsync(userId, result);
         await PublishBuildProgress(userId, preview.PreviewID, "Finalising project...", 90, progress);
         await PublishBuildProgress(userId, preview.PreviewID, result.Message, 100, progress, result);
@@ -415,6 +415,15 @@ public sealed class OnboardingService(
         var previewChapters = preview.Chapters.ToDictionary(chapter => chapter.TemporaryChapterKey, StringComparer.Ordinal);
         var previewScenes = preview.Scenes.ToDictionary(scene => scene.TemporarySceneKey, StringComparer.Ordinal);
         var includedChapterKeys = review.Chapters.Where(chapter => chapter.Include).Select(chapter => chapter.TemporaryChapterKey).ToHashSet(StringComparer.Ordinal);
+        if (includedChapterKeys.Count == 0)
+        {
+            throw new InvalidOperationException("Choose at least one chapter before continuing.");
+        }
+
+        if (!review.Scenes.Any(scene => scene.Include && includedChapterKeys.Contains(scene.TemporaryChapterKey)))
+        {
+            throw new InvalidOperationException("Choose at least one scene before continuing.");
+        }
 
         if (review.Chapters.Where(chapter => chapter.Include).Any(chapter => string.IsNullOrWhiteSpace(chapter.Title)))
         {
diff --git a/PlotLine/Views/Onboarding/ScanReview.cshtml b/PlotLine/Views/Onboarding/ScanReview.cshtml
index 018ec3f..c295598 100644
--- a/PlotLine/Views/Onboarding/ScanReview.cshtml
+++ b/PlotLine/Views/Onboarding/ScanReview.cshtml
@@ -85,8 +85,8 @@
                                 <input type="hidden" name="Chapters[@chapterIndex].TemporaryChapterKey" value="@chapter.TemporaryChapterKey" />
                                 <input type="hidden" name="Chapters[@chapterIndex].ChapterNumber" value="@chapter.ChapterNumber" />
                                 <label class="onboarding-review-toggle">
-                                    <input type="hidden" name="Chapters[@chapterIndex].Include" value="false" />
                                     <input type="checkbox" name="Chapters[@chapterIndex].Include" value="true" checked="@chapter.Include" data-review-kind="chapter" />
+                                    <input type="hidden" name="Chapters[@chapterIndex].Include" value="false" />
                                     Include chapter
                                 </label>
                                 <label class="onboarding-review-field">
@@ -104,8 +104,8 @@
                                                 <input type="hidden" name="Scenes[@sceneIndex].TemporaryChapterKey" value="@scene.TemporaryChapterKey" />
                                                 <input type="hidden" name="Scenes[@sceneIndex].SceneNumberWithinChapter" value="@scene.SceneNumberWithinChapter" />
                                                 <label class="onboarding-review-toggle">
-                                                    <input type="hidden" name="Scenes[@sceneIndex].Include" value="false" />
                                                     <input type="checkbox" name="Scenes[@sceneIndex].Include" value="true" checked="@scene.Include" data-review-kind="scene" />
+                                                    <input type="hidden" name="Scenes[@sceneIndex].Include" value="false" />
                                                     Include scene
                                                 </label>
                                                 <label class="onboarding-review-field">
@@ -116,8 +116,8 @@
                                                 @if (scene.WordCount == 0)
                                                 {
                                                     <label class="onboarding-review-toggle">
-                                                        <input type="hidden" name="Scenes[@sceneIndex].AllowZeroWords" value="false" />
                                                         <input type="checkbox" name="Scenes[@sceneIndex].AllowZeroWords" value="true" />
+                                                        <input type="hidden" name="Scenes[@sceneIndex].AllowZeroWords" value="false" />
                                                         Allow empty scene
                                                     </label>
                                                 }
@@ -172,8 +172,8 @@
                                             <input type="hidden" name="Characters[@characterIndex].TemporaryCharacterKey" value="@candidate.TemporaryCharacterKey" />
                                             <input type="hidden" name="Characters[@characterIndex].Category" value="@candidate.Category" />
                                             <label class="onboarding-review-toggle">
-                                                <input type="hidden" name="Characters[@characterIndex].Include" value="false" />
                                                 <input type="checkbox" name="Characters[@characterIndex].Include" value="true" checked="@candidate.Include" />
+                                                <input type="hidden" name="Characters[@characterIndex].Include" value="false" />
                                                 Include
                                             </label>
                                             <label class="onboarding-review-field">
@@ -218,8 +218,8 @@
                                                 <input type="hidden" name="Characters[@characterIndex].TemporaryCharacterKey" value="@candidate.TemporaryCharacterKey" />
                                                 <input type="hidden" name="Characters[@characterIndex].Category" value="@candidate.Category" />
                                                 <label class="onboarding-review-toggle">
-                                                    <input type="hidden" name="Characters[@characterIndex].Include" value="false" />
                                                     <input type="checkbox" name="Characters[@characterIndex].Include" value="true" checked="@candidate.Include" />
+                                                    <input type="hidden" name="Characters[@characterIndex].Include" value="false" />
                                                     Include
                                                 </label>
                                                 <label class="onboarding-review-field">