How would you use CancellationToken in an ASP.NET Core API endpoint?

In production I keep request cancellation, dependency timeouts, and host shutdown as related but separate signals. A client can remain connected while a dependency stalls, so each dependency still needs an explicit timeout inside the endpoint's latency budget. Once a write reaches its commit or publish boundary, I either complete it reliably or hand it to durable work rather than abandoning it halfway. An OperationCanceledException is expected when the relevant token was cancelled, so telemetry records it separately from faults and avoids noisy error alerts. Background work must not retain the request token or HttpContext; it copies the required data and uses the worker's shutdown token instead.