HTTP и REST API: методы, статус-коды, заголовки, идемпотентность?

POST /api/orders HTTP/1.1
Host: shop.example.uz
Content-Type: application/json
Authorization: Bearer eyJhbGciOi...
Accept: application/json

{ "productId": "3f2c...", "quantity": 2 }

HTTP/1.1 201 Created
Content-Type: application/json
Location: /api/orders/7a91c2

{ "id": "7a91c2", "status": "New", "total": 840000 }

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

orders.MapGet("/", async (IOrderService svc, int page = 1) => Results.Ok(await svc.ListAsync(page)));

orders.MapGet("/{id:guid}", async (Guid id, IOrderService svc) =>
    await svc.GetAsync(id) is { } order ? Results.Ok(order) : Results.NotFound());

orders.MapPost("/", async (CreateOrderRequest req, IOrderService svc) =>
{
    var created = await svc.CreateAsync(req);
    return Results.Created($"/api/orders/{created.Id}", created);    // 201 + Location
});

orders.MapDelete("/{id:guid}", async (Guid id, IOrderService svc) =>
    await svc.DeleteAsync(id) ? Results.NoContent() : Results.NotFound());

{
  "type": "https://tools.ietf.org/html/rfc9110#section-15.5.1",
  "title": "One or more validation errors occurred.",
  "status": 400,
  "errors": { "Quantity": ["Количество должно быть больше 0"] },
  "traceId": "00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01"
}