4. Minimal APIs

var orders = app.MapGroup("/api/orders").WithTags("Orders").RequireAuthorization();

orders.MapGet("/", async (IOrderService svc, [AsParameters] OrderQuery q, CancellationToken ct) =>
    TypedResults.Ok(await svc.ListAsync(q, ct)));

orders.MapGet("/{id:int}", async Task<Results<Ok<OrderDto>, NotFound>> (int id, IOrderService svc, CancellationToken ct) =>
    await svc.GetAsync(id, ct) is { } dto ? TypedResults.Ok(dto) : TypedResults.NotFound());

orders.MapPost("/", async (CreateOrderRequest req, IOrderService svc, CancellationToken ct) =>
{
    var dto = await svc.CreateAsync(req, ct);
    return TypedResults.Created($"/api/orders/{dto.Id}", dto);
}).AddEndpointFilter<ValidationFilter<CreateOrderRequest>>();