diff --git a/src/DotNetApiDiff/Commands/CompareCommand.cs b/src/DotNetApiDiff/Commands/CompareCommand.cs
index 357cc75..0ad120e 100644
--- a/src/DotNetApiDiff/Commands/CompareCommand.cs
+++ b/src/DotNetApiDiff/Commands/CompareCommand.cs
@@ -297,6 +297,23 @@ public override int Execute([NotNull] CommandContext context, [NotNull] CompareC
         }
     }
 
+    /// <summary>
+    /// Extracts the member name from a full element name
+    /// </summary>
+    /// <param name="elementName">The full element name</param>
+    /// <returns>The member name</returns>
+    private static string ExtractMemberName(string elementName)
+    {
+        if (string.IsNullOrEmpty(elementName))
+        {
+            return "Unknown"; // Or throw an exception if this is not expected
+        }
+
+        // For full names like "Namespace.Class.Method", extract just "Method"
+        var lastDotIndex = elementName.LastIndexOf('.');
+        return lastDotIndex >= 0 ? elementName.Substring(lastDotIndex + 1) : elementName;
+    }
+
     /// <summary>
     /// Executes the comparison logic using the configured services
     /// </summary>
@@ -599,19 +616,4 @@ private Models.ApiComparison CreateApiComparisonFromResult(Models.ComparisonResu
                 }).ToList()
         };
     }
-
-    /// <summary>
-    /// Extracts the member name from a full element name
-    /// </summary>
-    /// <param name="elementName">The full element name</param>
-    /// <returns>The member name</returns>
-    private static string ExtractMemberName(string elementName)
-    {
-        if (string.IsNullOrEmpty(elementName))
-            return "Unknown";
-
-        // For full names like "Namespace.Class.Method", extract just "Method"
-        var lastDotIndex = elementName.LastIndexOf('.');
-        return lastDotIndex >= 0 ? elementName.Substring(lastDotIndex + 1) : elementName;
-    }
 }
diff --git a/src/DotNetApiDiff/ExitCodes/ExitCodeManager.cs b/src/DotNetApiDiff/ExitCodes/ExitCodeManager.cs
index af66f8b..f459c49 100644
--- a/src/DotNetApiDiff/ExitCodes/ExitCodeManager.cs
+++ b/src/DotNetApiDiff/ExitCodes/ExitCodeManager.cs
@@ -134,7 +134,10 @@ public int GetExitCode(ApiComparison apiComparison)
             // Validate the comparison result
             if (!apiComparison.IsValid())
             {
-                _logger?.LogWarning("API comparison is invalid, returning ComparisonError exit code");
+                var errorMessage = string.IsNullOrEmpty(apiComparison.InvalidMessage)
+                    ? "API comparison is invalid"
+                    : $"API comparison is invalid: {apiComparison.InvalidMessage}";
+                _logger?.LogWarning("{ErrorMessage}, returning ComparisonError exit code", errorMessage);
                 return ComparisonError;
             }
 
@@ -177,10 +180,7 @@ public int GetExitCodeForException(Exception exception)
                 _ => UnexpectedError
             };
 
-            _logger?.LogWarning(
-                "Exception of type {ExceptionType} occurred, returning {ExitCode} exit code",
-                exception.GetType().Name,
-                GetExitCodeDescription(exitCode));
+            _logger?.LogWarning("Exception of type {ExceptionType} occurred, returning {ExitCode} exit code", exception.GetType().Name, GetExitCodeDescription(exitCode));
 
             return exitCode;
         }
diff --git a/src/DotNetApiDiff/Models/ApiComparison.cs b/src/DotNetApiDiff/Models/ApiComparison.cs
index 5aa1a55..a520b83 100644
--- a/src/DotNetApiDiff/Models/ApiComparison.cs
+++ b/src/DotNetApiDiff/Models/ApiComparison.cs
@@ -31,6 +31,11 @@ public class ApiComparison
     /// </summary>
     public ComparisonSummary Summary { get; set; } = new ComparisonSummary();
 
+    /// <summary>
+    /// Gets the validation error message if the comparison is invalid, empty if valid
+    /// </summary>
+    public string InvalidMessage { get; private set; } = string.Empty;
+
     /// <summary>
     /// Gets all changes as a single collection
     /// </summary>
@@ -63,34 +68,50 @@ public IEnumerable<ApiChange> AllChanges
     /// <returns>True if valid, false otherwise</returns>
     public bool IsValid()
     {
+        // Clear any previous validation message
+        InvalidMessage = string.Empty;
+
+        var errors = new List<string>();
+
         // Validate all changes
         var allChanges = AllChanges.ToList();
-        if (allChanges.Any(c => !c.IsValid()))
+        var invalidChanges = allChanges.Where(c => !c.IsValid()).ToList();
+        if (invalidChanges.Any())
         {
-            return false;
+            errors.Add($"Found {invalidChanges.Count} invalid change(s): {string.Join(", ", invalidChanges.Select(c => $"'{c.Description}' ({c.Type})"))}");
         }
 
         // Validate that additions only contain Added changes
-        if (Additions.Any(c => c.Type != ChangeType.Added))
+        var wrongAdditions = Additions.Where(c => c.Type != ChangeType.Added).ToList();
+        if (wrongAdditions.Any())
         {
-            return false;
+            errors.Add($"Additions collection contains {wrongAdditions.Count} change(s) with wrong type: {string.Join(", ", wrongAdditions.Select(c => $"'{c.Description}' ({c.Type})"))}");
         }
 
         // Validate that removals only contain Removed changes
-        if (Removals.Any(c => c.Type != ChangeType.Removed))
+        var wrongRemovals = Removals.Where(c => c.Type != ChangeType.Removed).ToList();
+        if (wrongRemovals.Any())
         {
-            return false;
+            errors.Add($"Removals collection contains {wrongRemovals.Count} change(s) with wrong type: {string.Join(", ", wrongRemovals.Select(c => $"'{c.Description}' ({c.Type})"))}");
         }
 
         // Validate that modifications only contain Modified changes
-        if (Modifications.Any(c => c.Type != ChangeType.Modified))
+        var wrongModifications = Modifications.Where(c => c.Type != ChangeType.Modified).ToList();
+        if (wrongModifications.Any())
         {
-            return false;
+            errors.Add($"Modifications collection contains {wrongModifications.Count} change(s) with wrong type: {string.Join(", ", wrongModifications.Select(c => $"'{c.Description}' ({c.Type})"))}");
         }
 
         // Validate that excluded only contain Excluded changes
-        if (Excluded.Any(c => c.Type != ChangeType.Excluded))
+        var wrongExcluded = Excluded.Where(c => c.Type != ChangeType.Excluded).ToList();
+        if (wrongExcluded.Any())
+        {
+            errors.Add($"Excluded collection contains {wrongExcluded.Count} change(s) with wrong type: {string.Join(", ", wrongExcluded.Select(c => $"'{c.Description}' ({c.Type})"))}");
+        }
+
+        if (errors.Count > 0)
         {
+            InvalidMessage = string.Join("; ", errors);
             return false;
         }
 
diff --git a/src/DotNetApiDiff/Reporting/HtmlFormatterScriban.cs b/src/DotNetApiDiff/Reporting/HtmlFormatterScriban.cs
index c9c932d..0d8913d 100644
--- a/src/DotNetApiDiff/Reporting/HtmlFormatterScriban.cs
+++ b/src/DotNetApiDiff/Reporting/HtmlFormatterScriban.cs
@@ -172,7 +172,7 @@ private object[] PrepareChangeSections(ComparisonResult result)
                 title = "Added Items",
                 count = addedItems.Count,
                 change_type = "added",
-                grouped_changes = GroupChanges(addedItems)
+                grouped_changes = GroupChangesByType(addedItems)
             });
         }
 
@@ -185,7 +185,7 @@ private object[] PrepareChangeSections(ComparisonResult result)
                 title = "Removed Items",
                 count = removedItems.Count,
                 change_type = "removed",
-                grouped_changes = GroupChanges(removedItems)
+                grouped_changes = GroupChangesByType(removedItems)
             });
         }
 
@@ -198,7 +198,7 @@ private object[] PrepareChangeSections(ComparisonResult result)
                 title = "Modified Items",
                 count = modifiedItems.Count,
                 change_type = "modified",
-                grouped_changes = GroupChanges(modifiedItems)
+                grouped_changes = GroupChangesByType(modifiedItems)
             });
         }
 
@@ -211,7 +211,7 @@ private object[] PrepareChangeSections(ComparisonResult result)
                 title = "Moved Items",
                 count = movedItems.Count,
                 change_type = "moved",
-                grouped_changes = GroupChanges(movedItems)
+                grouped_changes = GroupChangesByType(movedItems)
             });
         }
 
@@ -225,7 +225,7 @@ private object[] PrepareChangeSections(ComparisonResult result)
                 count = excludedItems.Count,
                 change_type = "excluded",
                 description = "The following items were intentionally excluded from the comparison:",
-                grouped_changes = GroupChanges(excludedItems)
+                grouped_changes = GroupChangesByType(excludedItems)
             });
         }
 
@@ -253,6 +253,85 @@ private object[] GroupChanges(List<ApiDifference> changes)
             }).ToArray();
     }
 
+    private object[] GroupChangesByType(List<ApiDifference> changes)
+    {
+        // Group changes by the containing type first
+        return changes
+            .GroupBy(d => ExtractContainingType(d.ElementName, d.ElementType))
+            .OrderBy(g => g.Key)
+            .Select(typeGroup => new
+            {
+                key = GetTypeDisplayName(typeGroup.Key),
+                full_type_name = typeGroup.Key,
+                count = typeGroup.Count(),
+                breaking_changes_count = typeGroup.Count(c => c.IsBreakingChange),
+                has_breaking_changes = typeGroup.Any(c => c.IsBreakingChange),
+                changes = typeGroup.OrderBy(c => c.ElementName).Select(c => new
+                {
+                    element_name = GetMemberDisplayName(c.ElementName, c.ElementType),
+                    full_element_name = c.ElementName,
+                    element_type = c.ElementType.ToString(),
+                    description = c.Description,
+                    is_breaking_change = c.IsBreakingChange,
+                    has_signatures = !string.IsNullOrEmpty(c.OldSignature) || !string.IsNullOrEmpty(c.NewSignature),
+                    old_signature = HtmlEscape(c.OldSignature),
+                    new_signature = HtmlEscape(c.NewSignature),
+                    details_id = $"details-{Guid.NewGuid():N}",
+                    severity = c.Severity.ToString().ToLower()
+                }).ToArray()
+            }).ToArray();
+    }
+
+    private string ExtractContainingType(string elementName, ApiElementType elementType)
+    {
+        // For type-level changes, the element name is the type name
+        if (elementType == ApiElementType.Type)
+        {
+            return elementName;
+        }
+
+        // For member-level changes, extract the type from the full name
+        // Expected format: TypeName.MemberName or Namespace.TypeName.MemberName
+        var lastDotIndex = elementName.LastIndexOf('.');
+        if (lastDotIndex > 0)
+        {
+            var typePart = elementName.Substring(0, lastDotIndex);
+
+            // Handle nested types (Type+NestedType.Member)
+            var plusIndex = typePart.LastIndexOf('+');
+            if (plusIndex > 0)
+            {
+                return typePart; // Keep the full nested type name
+            }
+
+            return typePart;
+        }
+
+        // Fallback for malformed names
+        return elementName;
+    }
+
+    private string GetTypeDisplayName(string typeName)
+    {
+        // Extract just the type name without namespace for display
+        var lastDotIndex = typeName.LastIndexOf('.');
+        return lastDotIndex > 0 ? typeName.Substring(lastDotIndex + 1) : typeName;
+    }
+
+    private string GetMemberDisplayName(string elementName, ApiElementType elementType)
+    {
+        // For type-level changes, return the simple type name
+        if (elementType == ApiElementType.Type)
+        {
+            var lastDotIndex = elementName.LastIndexOf('.');
+            return lastDotIndex > 0 ? elementName.Substring(lastDotIndex + 1) : elementName;
+        }
+
+        // For member-level changes, return just the member name
+        var memberDotIndex = elementName.LastIndexOf('.');
+        return memberDotIndex > 0 ? elementName.Substring(memberDotIndex + 1) : elementName;
+    }
+
     private object[] PrepareBreakingChangesData(IEnumerable<ApiDifference> breakingChanges)
     {
         return breakingChanges.OrderBy(d => d.Severity)
diff --git a/src/DotNetApiDiff/Reporting/HtmlTemplates/change-group.scriban b/src/DotNetApiDiff/Reporting/HtmlTemplates/change-group.scriban
index 45f02bc..1220023 100644
--- a/src/DotNetApiDiff/Reporting/HtmlTemplates/change-group.scriban
+++ b/src/DotNetApiDiff/Reporting/HtmlTemplates/change-group.scriban
@@ -1,41 +1,55 @@
 {{for group in grouped_changes}}
-<div class="change-group">
-    <h3>{{ group.key }} ({{ group.count }})</h3>
-    <div class="change-items">
-        {{for change in group.changes}}
-        <div class="change-item {{ change_type }}">
-            <div class="change-header">
-                <div class="change-name">
-                    <code>{{ change.element_name }}</code>
-                    {{if change.is_breaking_change}}
-                    <span class="breaking-badge">BREAKING</span>
-                    {{end}}
+<div class="type-group">
+    <div class="type-header">
+        <h3 class="type-name">
+            📁 {{ group.key }}
+            <span class="type-summary">
+                ({{ group.count }} change{{ if group.count != 1 }}s{{ end }}{{ if group.has_breaking_changes }}, {{ group.breaking_changes_count }} breaking{{ end }})
+            </span>
+        </h3>
+        {{if group.has_breaking_changes}}
+        <span class="breaking-type-badge">⚠️ Breaking Changes</span>
+        {{end}}
+    </div>
+
+    <div class="type-changes">
+        <div class="category-changes">
+            {{for change in group.changes}}
+            <div class="change-item {{ change.change_type }}">
+                <div class="change-header">
+                    <div class="change-name">
+                        <span class="element-type">{{ change.element_type }}</span>
+                        <code>{{ change.element_name }}</code>
+                        {{if change.is_breaking_change}}
+                        <span class="breaking-badge">BREAKING</span>
+                        {{end}}
+                    </div>
+                    <div class="change-description">{{ change.description }}</div>
                 </div>
-                <div class="change-description">{{ change.description }}</div>
-            </div>
-            {{if change.has_signatures}}
-            <div class="signature-toggle">
-                <button class="toggle-btn" onclick="toggleSignature('{{ change.details_id }}')">
-                    <span class="toggle-icon">▼</span> View Signature Details
-                </button>
-            </div>
-            <div id="{{ change.details_id }}" class="signature-details" style="display: none;">
-                {{if change.old_signature}}
-                <div class="signature-section">
-                    <h4>Old Signature:</h4>
-                    <pre><code class="csharp">{{ change.old_signature }}</code></pre>
+                {{if change.has_signatures}}
+                <div class="signature-toggle">
+                    <button class="toggle-btn" onclick="toggleSignature('{{ change.details_id }}')">
+                        <span class="toggle-icon">▼</span> View Signature Details
+                    </button>
                 </div>
-                {{end}}
-                {{if change.new_signature}}
-                <div class="signature-section">
-                    <h4>New Signature:</h4>
-                    <pre><code class="csharp">{{ change.new_signature }}</code></pre>
+                <div id="{{ change.details_id }}" class="signature-details" style="display: none;">
+                    {{if change.old_signature}}
+                    <div class="signature-section">
+                        <h4>Old Signature:</h4>
+                        <pre><code class="csharp">{{ change.old_signature }}</code></pre>
+                    </div>
+                    {{end}}
+                    {{if change.new_signature}}
+                    <div class="signature-section">
+                        <h4>New Signature:</h4>
+                        <pre><code class="csharp">{{ change.new_signature }}</code></pre>
+                    </div>
+                    {{end}}
                 </div>
                 {{end}}
             </div>
             {{end}}
         </div>
-        {{end}}
     </div>
 </div>
 {{end}}
diff --git a/src/DotNetApiDiff/Reporting/HtmlTemplates/main-layout.scriban b/src/DotNetApiDiff/Reporting/HtmlTemplates/main-layout.scriban
index b70a2e5..35326ca 100644
--- a/src/DotNetApiDiff/Reporting/HtmlTemplates/main-layout.scriban
+++ b/src/DotNetApiDiff/Reporting/HtmlTemplates/main-layout.scriban
@@ -56,39 +56,18 @@
         <section class="summary">
             <h2>📈 Summary</h2>
             <div class="summary-cards">
-                {{if result.summary.added_count > 0}}
                 <div class="summary-card added clickable" onclick="navigateToSection('added-items')">
                     <div class="card-number">{{ result.summary.added_count }}</div>
                     <div class="card-label">Added</div>
                 </div>
-                {{else}}
-                <div class="summary-card added">
-                    <div class="card-number">{{ result.summary.added_count }}</div>
-                    <div class="card-label">Added</div>
-                </div>
-                {{end}}
-                {{if result.summary.removed_count > 0}}
                 <div class="summary-card removed clickable" onclick="navigateToSection('removed-items')">
                     <div class="card-number">{{ result.summary.removed_count }}</div>
                     <div class="card-label">Removed</div>
                 </div>
-                {{else}}
-                <div class="summary-card removed">
-                    <div class="card-number">{{ result.summary.removed_count }}</div>
-                    <div class="card-label">Removed</div>
-                </div>
-                {{end}}
-                {{if result.summary.modified_count > 0}}
                 <div class="summary-card modified clickable" onclick="navigateToSection('modified-items')">
                     <div class="card-number">{{ result.summary.modified_count }}</div>
                     <div class="card-label">Modified</div>
                 </div>
-                {{else}}
-                <div class="summary-card modified">
-                    <div class="card-number">{{ result.summary.modified_count }}</div>
-                    <div class="card-label">Modified</div>
-                </div>
-                {{end}}
                 {{if result.summary.breaking_changes_count > 0}}
                 <div class="summary-card breaking clickable" onclick="navigateToSection('breaking-changes')">
                     <div class="card-number">{{ result.summary.breaking_changes_count }}</div>
@@ -120,9 +99,9 @@
         <!-- Breaking changes section -->
         {{if result.has_breaking_changes}}
         <section class="breaking-changes" id="breaking-changes">
-            <div class="section-header">
+            <div class="section-header" onclick="toggleSection('breaking-changes')">
                 <h2>⚠️ Breaking Changes</h2>
-                <button class="section-toggle collapsed" onclick="toggleSection('breaking-changes')">
+                <button class="section-toggle collapsed">
                     <span class="toggle-icon">▶</span>
                 </button>
             </div>
@@ -160,9 +139,9 @@
         <!-- Change sections -->
         {{for section in change_sections}}
         <section class="changes-section" id="{{ section.change_type }}-items">
-            <div class="section-header">
+            <div class="section-header" onclick="toggleSection('{{ section.change_type }}-items')">
                 <h2>{{ section.icon }} {{ section.title }} ({{ section.count }})</h2>
-                <button class="section-toggle collapsed" onclick="toggleSection('{{ section.change_type }}-items')">
+                <button class="section-toggle collapsed">
                     <span class="toggle-icon">▶</span>
                 </button>
             </div>
@@ -170,7 +149,67 @@
                 {{if section.description}}
                 <p class="section-description">{{ section.description }}</p>
                 {{end}}
-                {{ render_change_group section }}
+                <!-- Type groups within this change category -->
+                {{for group in section.grouped_changes}}
+                <div class="type-group" data-type-group-id="{{ section.change_type }}-{{ group.key | string.replace " " "-" | string.replace "." "-" | string.replace "`" "-" }}">
+                    <div class="type-header">
+                        <h3 class="type-name">
+                            📁 {{ group.key }}
+                            <span class="type-summary">
+                                ({{ group.count }} change{{ if group.count != 1 }}s{{ end }}{{ if group.has_breaking_changes }}, {{ group.breaking_changes_count }} breaking{{ end }})
+                            </span>
+                        </h3>
+                        <div class="type-header-controls">
+                            {{if group.has_breaking_changes}}
+                            <span class="breaking-type-badge">⚠️ Breaking Changes</span>
+                            {{end}}
+                            <button class="type-toggle collapsed" onclick="toggleTypeGroup(this.closest('.type-group').dataset.typeGroupId)">
+                                <span class="toggle-icon">▶</span>
+                            </button>
+                        </div>
+                    </div>
+
+                    <div class="type-changes collapsed" id="{{ section.change_type }}-{{ group.key | string.replace " " "-" | string.replace "." "-" | string.replace "`" "-" }}-content">
+                        <div class="category-changes">
+                            {{for change in group.changes}}
+                            <div class="change-item {{ section.change_type }}">
+                                <div class="change-header">
+                                    <div class="change-name">
+                                        <span class="element-type">{{ change.element_type }}</span>
+                                        <code>{{ change.element_name }}</code>
+                                        {{if change.is_breaking_change}}
+                                        <span class="breaking-badge">BREAKING</span>
+                                        {{end}}
+                                    </div>
+                                    <div class="change-description">{{ change.description }}</div>
+                                </div>
+                                {{if change.has_signatures}}
+                                <div class="signature-toggle">
+                                    <button class="toggle-btn" onclick="toggleSignature('{{ change.details_id }}')">
+                                        <span class="toggle-icon">▼</span> View Signature Details
+                                    </button>
+                                </div>
+                                <div id="{{ change.details_id }}" class="signature-details" style="display: none;">
+                                    {{if change.old_signature}}
+                                    <div class="signature-section">
+                                        <h5>Old Signature:</h5>
+                                        <pre><code class="csharp">{{ change.old_signature }}</code></pre>
+                                    </div>
+                                    {{end}}
+                                    {{if change.new_signature}}
+                                    <div class="signature-section">
+                                        <h5>New Signature:</h5>
+                                        <pre><code class="csharp">{{ change.new_signature }}</code></pre>
+                                    </div>
+                                    {{end}}
+                                </div>
+                                {{end}}
+                            </div>
+                            {{end}}
+                        </div>
+                    </div>
+                </div>
+                {{end}}
             </div>
         </section>
         {{end}}
diff --git a/src/DotNetApiDiff/Reporting/HtmlTemplates/scripts.js b/src/DotNetApiDiff/Reporting/HtmlTemplates/scripts.js
index e21bf9f..3cc0350 100644
--- a/src/DotNetApiDiff/Reporting/HtmlTemplates/scripts.js
+++ b/src/DotNetApiDiff/Reporting/HtmlTemplates/scripts.js
@@ -1,7 +1,9 @@
 function toggleSignature(detailsId) {
     const details = document.getElementById(detailsId);
-    const button = details.previousElementSibling.querySelector('.toggle-btn');
-    const icon = button.querySelector('.toggle-icon');
+    const button = details?.previousElementSibling?.querySelector('.toggle-btn');
+    const icon = button?.querySelector('.toggle-icon');
+
+    if (!details || !button || !icon) return;
 
     if (details.style.display === 'none') {
         details.style.display = 'block';
@@ -17,8 +19,10 @@ function toggleSignature(detailsId) {
 function toggleConfig() {
     const details = document.getElementById('config-details');
     const button = document.querySelector('.toggle-button');
-    const icon = button.querySelector('.toggle-icon');
-    const text = button.querySelector('.toggle-text');
+    const icon = button?.querySelector('.toggle-icon');
+    const text = button?.querySelector('.toggle-text');
+
+    if (!details || !button || !icon || !text) return;
 
     if (details.style.display === 'none') {
         details.style.display = 'block';
@@ -52,8 +56,10 @@ function getSectionState(sectionId) {
 function toggleSection(sectionId) {
     const section = document.getElementById(sectionId);
     const content = document.getElementById(sectionId + '-content');
-    const button = section.querySelector('.section-toggle');
-    const icon = button.querySelector('.toggle-icon');
+    const button = section?.querySelector('.section-toggle');
+    const icon = button?.querySelector('.toggle-icon');
+
+    if (!section || !content || !button || !icon) return;
 
     if (content.classList.contains('collapsed')) {
         // Expand section
@@ -70,6 +76,47 @@ function toggleSection(sectionId) {
     }
 }
 
+// Toggle type group functionality
+function toggleTypeGroup(typeGroupId) {
+    const content = document.getElementById(typeGroupId + '-content');
+    const group = document.querySelector(`.type-group[data-type-group-id="${typeGroupId}"]`);
+    const button = group?.querySelector('.type-toggle');
+    const icon = button?.querySelector('.toggle-icon');
+
+    if (!content || !group || !button || !icon) return;
+
+    if (content.classList.contains('collapsed')) {
+        // Expand type group
+        content.classList.remove('collapsed');
+        button.classList.remove('collapsed');
+        icon.textContent = '▶'; // Keep using ▶ and let CSS handle rotation
+        setTypeGroupState(typeGroupId, 'expanded');
+    } else {
+        // Collapse type group
+        content.classList.add('collapsed');
+        button.classList.add('collapsed');
+        icon.textContent = '▶'; // Keep using ▶ and let CSS handle rotation
+        setTypeGroupState(typeGroupId, 'collapsed');
+    }
+}
+
+// Type group session storage helpers
+function setTypeGroupState(typeGroupId, state) {
+    try {
+        sessionStorage.setItem('type-group-' + typeGroupId, state);
+    } catch (e) {
+        // Ignore storage errors
+    }
+}
+
+function getTypeGroupState(typeGroupId) {
+    try {
+        return sessionStorage.getItem('type-group-' + typeGroupId);
+    } catch (e) {
+        return null;
+    }
+}
+
 // Navigate to section with smooth scrolling and auto-expand
 function navigateToSection(sectionId) {
     const section = document.getElementById(sectionId);
@@ -127,6 +174,42 @@ function initializeSections() {
             }
         }
     });
+
+    // Initialize type groups to collapsed state by default
+    initializeTypeGroups();
+}
+
+// Initialize type groups to collapsed state by default
+function initializeTypeGroups() {
+    const typeGroups = document.querySelectorAll('.type-group');
+
+    typeGroups.forEach(typeGroup => {
+        const typeContent = typeGroup.querySelector('.type-changes');
+        const button = typeGroup.querySelector('.type-toggle');
+        const icon = button?.querySelector('.toggle-icon');
+        const typeGroupId = typeGroup.getAttribute('data-type-group-id');
+
+        if (!typeContent || !button || !icon || !typeGroupId) return;
+
+        // Check session storage first
+        const savedState = getTypeGroupState(typeGroupId);
+
+        if (savedState === 'expanded') {
+            // Expand based on saved state
+            typeContent.classList.remove('collapsed');
+            button.classList.remove('collapsed');
+            icon.textContent = '▶';
+        } else {
+            // Default to collapsed (including null/new sessions)
+            typeContent.classList.add('collapsed');
+            button.classList.add('collapsed');
+            icon.textContent = '▶';
+            // Save the default state if not already set
+            if (savedState === null) {
+                setTypeGroupState(typeGroupId, 'collapsed');
+            }
+        }
+    });
 }
 
 // Initialize sections when the page loads
diff --git a/src/DotNetApiDiff/Reporting/HtmlTemplates/styles.css b/src/DotNetApiDiff/Reporting/HtmlTemplates/styles.css
index d31d381..7cb259d 100644
--- a/src/DotNetApiDiff/Reporting/HtmlTemplates/styles.css
+++ b/src/DotNetApiDiff/Reporting/HtmlTemplates/styles.css
@@ -63,6 +63,12 @@ section h2 {
     padding: 15px 20px;
     margin: 0;
     border-bottom: 1px solid #dee2e6;
+    cursor: pointer;
+    transition: background-color 0.2s ease;
+}
+
+.section-header:hover {
+    background: #e9ecef;
 }
 
 .section-header h2 {
@@ -662,3 +668,195 @@ th {
         grid-template-columns: repeat(2, 1fr);
     }
 }
+
+/* Type-centric layout styles */
+.type-section {
+    margin: 20px 0;
+}
+
+.type-section .section-header {
+    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
+    border-left: 4px solid #007bff;
+}
+
+.type-summary {
+    font-size: 0.9rem;
+    color: #6c757d;
+    margin-left: 15px;
+}
+
+.breaking-summary {
+    color: #dc3545;
+    font-weight: 600;
+}
+
+.type-group {
+    padding: 0;
+}
+
+.type-header {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    padding: 15px 20px;
+    background: #f8f9fa;
+    border-bottom: 1px solid #dee2e6;
+    cursor: pointer;
+    transition: background-color 0.2s ease;
+}
+
+.type-header:hover {
+    background: #e9ecef;
+}
+
+.type-header-controls {
+    display: flex;
+    align-items: center;
+    gap: 10px;
+}
+
+.type-toggle {
+    background: none;
+    border: none;
+    cursor: pointer;
+    padding: 8px;
+    border-radius: 4px;
+    color: #6c757d;
+    transition: all 0.2s ease;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    min-width: 32px;
+    min-height: 32px;
+}
+
+.type-toggle:hover {
+    background-color: #e9ecef;
+    color: #495057;
+}
+
+.type-toggle:focus {
+    outline: 2px solid #007bff;
+    outline-offset: 2px;
+}
+
+.type-toggle.collapsed .toggle-icon {
+    transform: rotate(0deg); /* No rotation - ▶ points right when collapsed */
+}
+
+.type-toggle:not(.collapsed) .toggle-icon {
+    transform: rotate(90deg); /* Rotate ▶ to point down when expanded */
+}
+
+.type-name {
+    margin: 0;
+    font-size: 1.3rem;
+    color: #495057;
+}
+
+.type-summary span {
+    font-size: 0.85rem;
+    color: #6c757d;
+    font-weight: normal;
+}
+
+.breaking-type-badge {
+    background: #dc3545;
+    color: white;
+    padding: 4px 8px;
+    border-radius: 4px;
+    font-size: 0.75rem;
+    font-weight: 600;
+    text-transform: uppercase;
+}
+
+.type-changes {
+    padding: 20px;
+    transition: all 0.3s ease;
+    overflow: hidden;
+}
+
+.type-changes.collapsed {
+    max-height: 0;
+    opacity: 0;
+    padding-top: 0;
+    padding-bottom: 0;
+    margin-top: 0;
+    margin-bottom: 0;
+}
+
+.type-changes:not(.collapsed) {
+    max-height: none;
+    opacity: 1;
+}
+
+.change-category {
+    margin-bottom: 25px;
+}
+
+.change-category:last-child {
+    margin-bottom: 0;
+}
+
+.category-header {
+    margin-bottom: 15px;
+    padding-bottom: 8px;
+    border-bottom: 2px solid #e9ecef;
+}
+
+.category-header h4 {
+    margin: 0;
+    font-size: 1.1rem;
+    color: #495057;
+    display: flex;
+    align-items: center;
+    gap: 8px;
+}
+
+.category-changes {
+    margin-left: 20px;
+}
+
+.change-item {
+    margin-bottom: 15px;
+    padding: 15px;
+    border-radius: 6px;
+    border-left: 4px solid #e9ecef;
+}
+
+.change-item.added {
+    background-color: #f8fff9;
+    border-left-color: #28a745;
+}
+
+.change-item.removed {
+    background-color: #fff8f8;
+    border-left-color: #dc3545;
+}
+
+.change-item.modified {
+    background-color: #fefcf2;
+    border-left-color: #ffc107;
+}
+
+.change-item.moved {
+    background-color: #f8f9ff;
+    border-left-color: #6f42c1;
+}
+
+.change-item.excluded {
+    background-color: #f8f9fa;
+    border-left-color: #6c757d;
+}
+
+.element-type {
+    display: inline-block;
+    background: #e9ecef;
+    color: #495057;
+    padding: 2px 6px;
+    border-radius: 3px;
+    font-size: 0.75rem;
+    font-weight: 600;
+    text-transform: uppercase;
+    margin-right: 8px;
+}
diff --git a/src/DotNetApiDiff/Reporting/HtmlTemplates/type-group.scriban b/src/DotNetApiDiff/Reporting/HtmlTemplates/type-group.scriban
new file mode 100644
index 0000000..708adb1
--- /dev/null
+++ b/src/DotNetApiDiff/Reporting/HtmlTemplates/type-group.scriban
@@ -0,0 +1,60 @@
+<div class="type-group">
+    <div class="type-header">
+        <h3 class="type-name">
+            📁 {{ type_name }}
+            <span class="type-summary">
+                ({{ total_changes }} change{{ if total_changes != 1 }}s{{ end }}{{ if has_breaking_changes }}, {{ breaking_changes_count }} breaking{{ end }})
+            </span>
+        </h3>
+        {{if has_breaking_changes}}
+        <span class="breaking-type-badge">⚠️ Breaking Changes</span>
+        {{end}}
+    </div>
+
+    <div class="type-changes">
+        {{for category in change_categories}}
+        <div class="change-category">
+            <div class="category-header">
+                <h4>{{ category.icon }} {{ category.title }} ({{ category.count }})</h4>
+            </div>
+            <div class="category-changes">
+                {{for change in category.changes}}
+                <div class="change-item {{ category.change_type }}">
+                    <div class="change-header">
+                        <div class="change-name">
+                            <span class="element-type">{{ change.element_type }}</span>
+                            <code>{{ change.element_name }}</code>
+                            {{if change.is_breaking_change}}
+                            <span class="breaking-badge">BREAKING</span>
+                            {{end}}
+                        </div>
+                        <div class="change-description">{{ change.description }}</div>
+                    </div>
+                    {{if change.has_signatures}}
+                    <div class="signature-toggle">
+                        <button class="toggle-btn" onclick="toggleSignature('{{ change.details_id }}')">
+                            <span class="toggle-icon">▼</span> View Signature Details
+                        </button>
+                    </div>
+                    <div id="{{ change.details_id }}" class="signature-details" style="display: none;">
+                        {{if change.old_signature}}
+                        <div class="signature-section">
+                            <h5>Old Signature:</h5>
+                            <pre><code class="csharp">{{ change.old_signature }}</code></pre>
+                        </div>
+                        {{end}}
+                        {{if change.new_signature}}
+                        <div class="signature-section">
+                            <h5>New Signature:</h5>
+                            <pre><code class="csharp">{{ change.new_signature }}</code></pre>
+                        </div>
+                        {{end}}
+                    </div>
+                    {{end}}
+                </div>
+                {{end}}
+            </div>
+        </div>
+        {{end}}
+    </div>
+</div>
diff --git a/tests/DotNetApiDiff.Tests/Integration/CliWorkflowTests.cs b/tests/DotNetApiDiff.Tests/Integration/CliWorkflowTests.cs
index 1a5edfd..3033c20 100644
--- a/tests/DotNetApiDiff.Tests/Integration/CliWorkflowTests.cs
+++ b/tests/DotNetApiDiff.Tests/Integration/CliWorkflowTests.cs
@@ -138,8 +138,8 @@ public void CliWorkflow_WithValidAssemblies_ShouldSucceed()
         var result = RunCliCommand(arguments);
 
         // Assert
-        // Exit code 2 is expected when there are breaking changes, which is normal for our test assemblies
-        Assert.True(result.ExitCode == 0 || result.ExitCode == 2, $"CLI should execute successfully. Exit code: {result.ExitCode}");
+        // Exit code 1 is expected when there are breaking changes, which is normal for our test assemblies
+        Assert.True(result.ExitCode == 0 || result.ExitCode == 1, $"CLI should execute successfully. Exit code: {result.ExitCode}");
         Assert.False(string.IsNullOrEmpty(result.StandardOutput), "Should produce output");
     }
 
@@ -163,8 +163,8 @@ public void CliWorkflow_WithConfigFile_ShouldApplyConfiguration()
         var result = RunCliCommand(arguments);
 
         // Assert
-        // Exit code 2 is expected when there are breaking changes, which is normal for our test assemblies
-        Assert.True(result.ExitCode == 0 || result.ExitCode == 2, $"CLI should execute successfully with config. Exit code: {result.ExitCode}");
+        // Exit code 1 is expected when there are breaking changes, which is normal for our test assemblies
+        Assert.True(result.ExitCode == 0 || result.ExitCode == 1, $"CLI should execute successfully with config. Exit code: {result.ExitCode}");
         Assert.False(string.IsNullOrEmpty(result.StandardOutput), "Should produce JSON output");
     }
 
@@ -198,8 +198,8 @@ public void CliWorkflow_WithConfigFileOutputSettings_ShouldUseConfigurationValue
         var result = RunCliCommand(arguments);
 
         // Assert
-        // Exit code 2 is expected when there are breaking changes, which is normal for our test assemblies
-        Assert.True(result.ExitCode == 0 || result.ExitCode == 2, $"CLI should execute successfully with config output settings. Exit code: {result.ExitCode}");
+        // Exit code 1 is expected when there are breaking changes, which is normal for our test assemblies
+        Assert.True(result.ExitCode == 0 || result.ExitCode == 1, $"CLI should execute successfully with config output settings. Exit code: {result.ExitCode}");
 
         // The output file should have been created (this tests that OutputPath from config was used)
         Assert.True(File.Exists(expectedOutputFile), $"Output file should have been created at: {expectedOutputFile}");
@@ -233,8 +233,8 @@ public void CliWorkflow_CommandLineOverridesConfigOutputSettings_ShouldUseComman
         var result = RunCliCommand(arguments);
 
         // Assert
-        // Exit code 2 is expected when there are breaking changes, which is normal for our test assemblies
-        Assert.True(result.ExitCode == 0 || result.ExitCode == 2, $"CLI should execute successfully with command line override. Exit code: {result.ExitCode}");
+        // Exit code 1 is expected when there are breaking changes, which is normal for our test assemblies
+        Assert.True(result.ExitCode == 0 || result.ExitCode == 1, $"CLI should execute successfully with command line override. Exit code: {result.ExitCode}");
 
         // The command line output file should have been created (not the config one)
         Assert.True(File.Exists(commandLineOutputFile), $"Command line output file should have been created at: {commandLineOutputFile}");
@@ -364,8 +364,8 @@ public void CliWorkflow_WithDifferentOutputFormats_ShouldSucceed(string outputFo
         var result = RunCliCommand(arguments);
 
         // Assert
-        // Exit code 2 is expected when there are breaking changes, which is normal for our test assemblies
-        Assert.True(result.ExitCode == 0 || result.ExitCode == 2, $"CLI should execute successfully with {outputFormat} format. Exit code: {result.ExitCode}");
+        // Exit code 1 is expected when there are breaking changes, which is normal for our test assemblies
+        Assert.True(result.ExitCode == 0 || result.ExitCode == 1, $"CLI should execute successfully with {outputFormat} format. Exit code: {result.ExitCode}");
         Assert.False(string.IsNullOrEmpty(result.StandardOutput), $"Should produce {outputFormat} output");
 
         // Verify output format specific content
@@ -422,8 +422,8 @@ public void CliWorkflow_WithNamespaceFiltering_ShouldApplyFilters()
         var result = RunCliCommand(arguments);
 
         // Assert
-        // Exit code 2 is expected when there are breaking changes, which is normal for our test assemblies
-        Assert.True(result.ExitCode == 0 || result.ExitCode == 2, $"CLI should succeed with namespace filtering. Exit code: {result.ExitCode}");
+        // Exit code 1 is expected when there are breaking changes, which is normal for our test assemblies
+        Assert.True(result.ExitCode == 0 || result.ExitCode == 1, $"CLI should succeed with namespace filtering. Exit code: {result.ExitCode}");
         Assert.False(string.IsNullOrEmpty(result.StandardOutput), "Should produce filtered output");
     }
 
@@ -445,8 +445,8 @@ public void CliWorkflow_WithVerboseOutput_ShouldProduceDetailedLogs()
         var result = RunCliCommand(arguments);
 
         // Assert
-        // Exit code 2 is expected when there are breaking changes, which is normal for our test assemblies
-        Assert.True(result.ExitCode == 0 || result.ExitCode == 2, $"CLI should succeed with verbose output. Exit code: {result.ExitCode}");
+        // Exit code 1 is expected when there are breaking changes, which is normal for our test assemblies
+        Assert.True(result.ExitCode == 0 || result.ExitCode == 1, $"CLI should succeed with verbose output. Exit code: {result.ExitCode}");
         Assert.False(string.IsNullOrEmpty(result.StandardOutput), "Should produce verbose output");
     }
 
@@ -468,8 +468,8 @@ public void CliWorkflow_WithNoColorOption_ShouldDisableColors()
         var result = RunCliCommand(arguments);
 
         // Assert
-        // Exit code 2 is expected when there are breaking changes, which is normal for our test assemblies
-        Assert.True(result.ExitCode == 0 || result.ExitCode == 2, $"CLI should succeed with no-color option. Exit code: {result.ExitCode}");
+        // Exit code 1 is expected when there are breaking changes, which is normal for our test assemblies
+        Assert.True(result.ExitCode == 0 || result.ExitCode == 1, $"CLI should succeed with no-color option. Exit code: {result.ExitCode}");
         Assert.False(string.IsNullOrEmpty(result.StandardOutput), "Should produce output without colors");
     }
 
@@ -536,8 +536,8 @@ public void CliWorkflow_ConfigurationJsonEnumParsing_ShouldParseOutputFormatCorr
         var result = RunCliCommand(arguments);
 
         // Assert
-        // Exit code 2 is expected when there are breaking changes
-        Assert.True(result.ExitCode == 0 || result.ExitCode == 2, $"CLI should execute successfully. Exit code: {result.ExitCode}");
+        // Exit code 1 is expected when there are breaking changes
+        Assert.True(result.ExitCode == 0 || result.ExitCode == 1, $"CLI should execute successfully. Exit code: {result.ExitCode}");
 
         // Verify the output file was created (tests OutputPath config usage)
         Assert.True(File.Exists(outputFile), $"Output file should have been created at: {outputFile}");
@@ -614,8 +614,8 @@ public void CliWorkflow_CommandLineOverridesConfig_ShouldUseExplicitCommandLineF
         var result = RunCliCommand(arguments);
 
         // Assert
-        // Exit code 2 is expected when there are breaking changes
-        Assert.True(result.ExitCode == 0 || result.ExitCode == 2, $"CLI should execute successfully. Exit code: {result.ExitCode}");
+        // Exit code 1 is expected when there are breaking changes
+        Assert.True(result.ExitCode == 0 || result.ExitCode == 1, $"CLI should execute successfully. Exit code: {result.ExitCode}");
 
         // Verify the output file was created
         Assert.True(File.Exists(outputFile), $"Output file should have been created at: {outputFile}");
diff --git a/tests/DotNetApiDiff.Tests/Reporting/HtmlFormatterScribanTests.cs b/tests/DotNetApiDiff.Tests/Reporting/HtmlFormatterScribanTests.cs
index d9907b7..2a80b70 100644
--- a/tests/DotNetApiDiff.Tests/Reporting/HtmlFormatterScribanTests.cs
+++ b/tests/DotNetApiDiff.Tests/Reporting/HtmlFormatterScribanTests.cs
@@ -71,7 +71,7 @@ public void Format_WithAddedItems_IncludesAddedSection()
         Assert.Contains("Added Items", report);
         Assert.Contains("NewClass", report);
         Assert.Contains("Added new class", report);
-        Assert.Contains("Type (1)", report); // Group header should show count
+        Assert.Contains("📁 NewClass", report); // Type group header should show type name
     }
 
     [Fact]
@@ -90,7 +90,7 @@ public void Format_WithRemovedItems_IncludesRemovedSection()
                 {
                     ChangeType = ChangeType.Removed,
                     ElementType = ApiElementType.Method,
-                    ElementName = "OldMethod",
+                    ElementName = "OldClass.OldMethod",
                     Description = "Removed method",
                     Severity = SeverityLevel.Info
                 }
@@ -105,7 +105,7 @@ public void Format_WithRemovedItems_IncludesRemovedSection()
         Assert.Contains("Removed Items", report);
         Assert.Contains("OldMethod", report);
         Assert.Contains("Removed method", report);
-        Assert.Contains("Method (1)", report); // Group header should show count
+        Assert.Contains("📁 OldClass", report); // Type group header should show type name
     }
 
     [Fact]