The journey of every round

Use IRequestHandler<TRequest, TResponse> with a request that wraps an IAsyncEnumerable<T> stream for paged streaming response.

Implement a JwtBearerOptions handler that validates a custom claim transformation using IClaimsTransformation in DI.

Add health checks using IHealthCheckPublisher with a custom HealthCheckResult that exposes degraded state metrics.

Implement an IObservable<T> stream over Channel<T> with backpressure, completing on CancellationToken cancellation.

Set up a circuit breaker via ResiliencePipelineBuilder with exponential backoff, AddTimeout, AddRetry, and AddCircuitBreaker stacked.

Add a custom IValidatorFactory hook that resolves AbstractValidator<T> from DI and runs ValidationContext<T> with a custom rule set name.

Write a Roslyn ISourceGenerator that emits boilerplate INotifyPropertyChanged for all [Notify] attributed properties.

Implement a token refresh middleware using IMiddleware (not the convention-based one), with RequestDelegate and DelegatingHandler chained.

Use IRequestPreProcessor<TRequest> in MediatR to inject the current ClaimsPrincipal into every request before handler dispatch.

Add IDistributedCache with backplane invalidation on a config change, using IOptionsMonitor<T> reload notifications.

Wire OpenTelemetry tracing: ActivitySource for traces, Meter for metrics, with ILogger<T> structured logs feeding both.

Implement a custom AuthenticationHandler<TOptions> for a header-based API key, including ChallengeAsync and AuthenticateResult.

Write a BackgroundService that uses IServiceScopeFactory to resolve a scoped DbContext per iteration, with retry via ResiliencePipeline.

Add a Channel<T>-based bounded producer-consumer with backpressure, using BoundedChannelFullMode.Wait and a CancellationToken end-to-end.

Write a custom IPipelineBehavior<TRequest, TResponse> for MediatR that captures FluentValidation errors and re-throws as a structured ValidationException.

Implement a graceful shutdown handler using IHostApplicationLifetime, with a 30-second drain window and structured logging at each phase.

Find the date with the highest number of new signups in a users table.

Use HAVING to filter aggregate results: orders with more than 5 line items.

Write a SQL query joining 4 tables (customers, orders, line_items, products) to produce a customer-order-product report.

Find products in the top 10 percent by revenue using NTILE.

Calculate the gap in days between consecutive logins per user using LAG.

Use EXISTS to find customers with at least one cancelled order.

Find the median salary in each department using window functions.

Write a recursive CTE to walk an employee-manager hierarchy from any starting employee.