Lists and search

Do not Add in a loop for mid or large lists. AddRange raises one CollectionChanged Reset. Large lists must also virtualize — ItemsRepeater / ListView virtualization. The framework will not pretend 100,000 realized rows are fine.

var items = new ObservableRangeCollection<Product>();
items.AddRange(page);      // one CollectionChanged Reset
items.ReplaceRange(next);

PagedCollection<T> / DelegatePagedCollection<T> own load-more, refresh, and retry — not a live inbox. SnapshotCollection<T> loads once in InitializeAsync; later LoadAsync calls are no-ops unless force is true. SearchQuery.Text binds to a TextBox or MvvmSearch; filter from CommittedText after debounce.

public sealed class InboxViewModel : ViewModel
{
    public SnapshotCollection<Conversation> Inbox { get; }
    public SearchQuery Search { get; } = new();

    public InboxViewModel(IInbox catalog)
    {
        Inbox = new SnapshotCollection<Conversation>(
            ct => catalog.ListAsync(Search.CommittedText, ct));
    }

    protected override Task InitializeAsync(CancellationToken cancellationToken) =>
        Inbox.LoadAsync(cancellationToken: cancellationToken);
}

await Products.RefreshAsync(ct);
await Products.LoadMoreAsync(ct);