API Visualization with Scalar

Program.cs

using FastEndpoints.Swagger;
using Scalar.AspNetCore; //dotnet add package Scalar.AspNetCore

var bld = WebApplication.CreateBuilder(args);
bld.Services
   .AddFastEndpoints()
   .SwaggerDocument(); //define a swagger doc - v1 by default

var app = bld.Build();
app.UseFastEndpoints(); //must come before the UseOpenApi() call

if (app.Environment.IsDevelopment())
{
    //scalar by default looks for the swagger json file here: 
    app.UseOpenApi(c => c.Path = "/openapi/{documentName}.json");    
    app.MapScalarApiReference();
}

app.Run();

//scalar ui can be accessed at: http://localhost:{port}/scalar/v1

So I have discovered that if you want the document name to be different, you must specify the document name in the MapScalarApiReference options. This is seemingly because Scalar defaults to "v1". Please let me know if there is a smoother way to do this.

Example:

const string openApiDocName = "my-api-v1";

app.UseOpenApi(options =>
{
  options.Path = "/openapi/{documentName}.json";
});
app.MapScalarApiReference(
  "/api-reference",
  options => options
             .WithTheme(ScalarTheme.Kepler)
             .AddDocument("v1", "My API v1", $"/openapi/{openApiDocName}.json"));

@matthewj-dev
sorry i just saw your question. github didn't send a notification for some reason.
there's no way around having to tell scalar what your "non-default" document name is. but you only need to specify the document name like so:

app.MapScalarApiReference(o => o.AddDocument("my-api-v1"));

visiting /scalar with automatically load up that document since scalar knows about it.
or you'd have to manually visit /scalar/my-api-v1