some changes for progress

Wino.Mail.ViewModels/MailListPageViewModel.cs

@@ -571,7 +571,7 @@ public partial class MailListPageViewModel : MailBaseViewModel,
             return;
         }
 
-        var viewModels = PrepareMailViewModels(items);
+        var viewModels = await PrepareMailViewModelsAsync(items).ConfigureAwait(false);
 
         await MailCollection.AddRangeAsync(viewModels, false);
         await ExecuteUIThread(() => { IsInitializingFolder = false; });
@@ -738,9 +738,19 @@ public partial class MailListPageViewModel : MailBaseViewModel,
         }
     }
 
-    private List<MailItemViewModel> PrepareMailViewModels(IEnumerable<MailCopy> mailItems)
+    private async Task<List<MailItemViewModel>> PrepareMailViewModelsAsync(IEnumerable<MailCopy> mailItems, CancellationToken cancellationToken = default)
     {
-        return mailItems.Select(a => new MailItemViewModel(a)).ToList();
+        // Run ViewModel creation on background thread to avoid blocking UI
+        return await Task.Run(() =>
+        {
+            var viewModels = new List<MailItemViewModel>();
+            foreach (var mailItem in mailItems)
+            {
+                cancellationToken.ThrowIfCancellationRequested();
+                viewModels.Add(new MailItemViewModel(mailItem));
+            }
+            return viewModels;
+        }, cancellationToken).ConfigureAwait(false);
     }
 
     [RelayCommand]
@@ -764,7 +774,11 @@ public partial class MailListPageViewModel : MailBaseViewModel,
             if (ActiveFolder == null)
                 return;
 
-            await ExecuteUIThread(() => { IsInitializingFolder = true; });
+            await ExecuteUIThread(() => { 
+                IsInitializingFolder = true;
+                // Show initial loading progress
+                UpdateBarMessage(InfoBarMessageType.Information, ActiveFolder.FolderName, "Loading emails...");
+            });
 
             // Folder is changed during initialization.
             // Just cancel the existing one and wait for new initialization.
@@ -855,11 +869,21 @@ public partial class MailListPageViewModel : MailBaseViewModel,
 
             if (!listManipulationCancellationTokenSource.IsCancellationRequested)
             {
+                // Update progress: Creating view models
+                await ExecuteUIThread(() => {
+                    UpdateBarMessage(InfoBarMessageType.Information, ActiveFolder.FolderName, $"Processing {items.Count} emails...");
+                });
+
                 // Here they are already threaded if needed.
                 // We don't need to insert them one by one.
                 // Just create VMs and do bulk insert.
 
-                var viewModels = PrepareMailViewModels(items);
+                var viewModels = await PrepareMailViewModelsAsync(items, cancellationToken).ConfigureAwait(false);
+
+                // Update progress: Adding to collection
+                await ExecuteUIThread(() => {
+                    UpdateBarMessage(InfoBarMessageType.Information, ActiveFolder.FolderName, "Finalizing...");
+                });
 
                 await MailCollection.AddRangeAsync(viewModels, clearIdCache: true);
 
@@ -895,6 +919,9 @@ public partial class MailListPageViewModel : MailBaseViewModel,
 
                 OnPropertyChanged(nameof(CanSynchronize));
                 NotifyItemFoundState();
+                
+                // Clear the loading message after completion
+                IsBarOpen = false;
             });
         }
     }