diff --git a/SharepointToolbox/App.xaml.cs b/SharepointToolbox/App.xaml.cs
index bbe6dbb..b0a4e4c 100644
--- a/SharepointToolbox/App.xaml.cs
+++ b/SharepointToolbox/App.xaml.cs
@@ -158,6 +158,9 @@ public partial class App : Application
         services.AddTransient<FolderStructureViewModel>();
         services.AddTransient<FolderStructureView>();
 
+        // Phase 17: Group Expansion
+        services.AddTransient<ISharePointGroupResolver, SharePointGroupResolver>();
+
         // Phase 7: User Access Audit
         services.AddTransient<IUserAccessAuditService, UserAccessAuditService>();
         services.AddTransient<IGraphUserSearchService, GraphUserSearchService>();