Async streams, channels, performance, architecture, and a production-shaped API capstone.
Stream results with IAsyncEnumerable, connect producers and consumers with Channel<T>, and run background services with cancellation and shutdown.
Measure allocations and throughput, use Span and Memory to reduce copying, pool buffers, and benchmark changes with BenchmarkDotNet.
Use dependency injection lifetimes, health checks, resilient clients, configuration, and observability to make a service operable.
Combine EF Core, validation, auth, background processing, tests, logging, metrics, Docker, and a deployment checklist in one service.