The journey of every round

Implement schema migration on startup using IHostedService that runs DbContext.Database.MigrateAsync before the host accepts traffic.

Build a typed HttpClient with a DelegatingHandler stack that injects IHttpContextAccessor's current trace ID into outgoing headers.

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.

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

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