Two easily missed details in paginated ASP.NET Core CRUD: sort ties and duplicate emails

A customer CRUD application can appear finished through the UI, yet two less visible behaviors need careful attention. The first concerns sorting, where records with equal sort values have no guaranteed order unless the unique ID is added as a secondary key. The second concerns duplicate email addresses, which an existence check alone cannot fully prevent when concurrent requests race, so a database unique index and translation of the resulting SQL Server error into a 409 response are also needed. The author's example clamps page parameters and warns that offset pagination still does not provide a consistent snapshot when records change between requests. The duplicate-email translation also assumes any uniqueness failure means a duplicate email, which must be revisited if more unique constraints are added. These observations come from a local demo and prior verification, not a production-readiness claim.