private async IAsyncEnumerable<DocumentKey> ListDocumentsAsync(
    OrgSlug org,
    DocumentRelativePath? startAfter,
    [EnumeratorCancellation] CancellationToken cancellationToken)
{
    var isFirstRequest = true;
    var requestBuilder = () =>
    {
        var r = new ListObjectsV2Request
        {
            Prefix = org.ToString(),
            StartAfter = isFirstRequest && startAfter is { } doc
                ? new DocumentKey(org, doc.Type, doc.Name).ToString()
                : null,
        };

        isFirstRequest = false;

        return r;
    };

   await foreach (var obj in EnumerateObjectsAsync(requestBuilder, cancellationToken))
       if (DocumentKey.TryFromS3Key(obj.Key, out var key))
           yield return key.Value;
}