```ruby
# frozen_string_literal: true

class Auth::RegistrationsController < Devise::RegistrationsController
  layout :determine_layout

  before_action :check_enabled_registrations, only: [:new, :create]
  before_action :configure_sign_up_params, only: [:create]

  protected

  def build_resource(hash = nil)
    super(hash)
    resource.build_account if resource.account.nil?
  end

  def configure_sign_up_params
    devise_parameter_sanitizer.permit(:sign_up) do |u|
      u.permit({ account_attributes: [:username] }, :email, :password, :password_confirmation)
    end
  end

  def after_sign_up_path_for(_resource)
    new_user_session_path
  end

  def after_inactive_sign_up_path_for(_resource)
    new_user_session_path
  end

  def check_enabled_registrations
    redirect_to root_path if Rails.configuration.x.single_user_mode || !Setting.open_registrations
  end

  private

  def determine_layout
    %w(edit update).include?(action_name) ? 'admin' : 'auth'
  end
end
```

Set default user locale on signup
user
```ruby
# frozen_string_literal: true

class Auth::RegistrationsController < Devise::RegistrationsController
  layout :determine_layout

  before_action :check_enabled_registrations, only: [:new, :create]
  before_action :configure_sign_up_params, only: [:create]

  protected

  def build_resource(hash = nil)
    super(hash)
    resource.locale = I18n.locale if I18n.locale_available?(locale)
    resource.build_account if resource.account.nil?
  end

  def configure_sign_up_params
    devise_parameter_sanitizer.permit(:sign_up) do |u|
      u.permit({ account_attributes: [:username] }, :email, :password, :password_confirmation)
    end
  end

  def after_sign_up_path_for(_resource)
    new_user_session_path
  end

  def after_inactive_sign_up_path_for(_resource)
    new_user_session_path
  end

  def check_enabled_registrations
    redirect_to root_path if Rails.configuration.x.single_user_mode || !Setting.open_registrations
  end

  private

  def determine_layout
    %w(edit update).include?(action_name) ? 'admin' : 'auth'
  end
end
```
assistant