Time stamps

Track CreatedTimeUtc, LastUpdatedTimeUtc, and the raw `_ts` for every item.

TimeStampedItem and FullItem add three timestamp properties out of the box:

Property	Source	Notes
`CreatedTimeUtc`	Set by the library on `CreateAsync`	If you set it before `CreateAsync`, the library leaves your value alone. Existing data may have `null`.
`LastUpdatedTimeUtc`	Derived from Cosmos’s `_ts`	Friendly `DateTime`.
`LastUpdatedTimeRaw`	Cosmos’s `_ts`	Raw seconds since epoch.

The _ts property is documented in the official Cosmos DB REST reference — it is automatically maintained on every update.

using Microsoft.Azure.CosmosRepository;

public class AuditEntry : TimeStampedItem
{
    public string Action { get; set; } = null!;
    public string PerformedBy { get; set; } = null!;
}

var repository = serviceProvider.GetRequiredService<IRepository<AuditEntry>>();

var entry = await repository.CreateAsync(new AuditEntry
{
    Action = "DELETE",
    PerformedBy = "alice@contoso.com",
});

Console.WriteLine($"Created at {entry.CreatedTimeUtc:O}");
Console.WriteLine($"Last updated at {entry.LastUpdatedTimeUtc:O}");