How can I add a services directory to the load path in Rails?

First of all, the code under app folder will be loaded without any config.

I think the problem was the folder structure doesn't match with your class definition.

So this config will work:

app/services/foo/test.rb

module Foo
  class Test
  end
end

My clue is, for example we have app/controllers/api/v1/users_controllers.rb and the class constant will be Api::V1::UsersController, not Controllers::Api::V1::UsersController

Update

Conventionally, we usually use FooServices instead of Foo, it is clearer, for example:

app/services/foo_services/bar_parser.rb

module FooServices
  class BarParser
    # Do stuff
  end
end

So we understand that every class inside foo_services folder is a service which related to Foo

After add new dir, reload spring spring stop