See [this line](https://github.com/Compass/compass-rails/blob/master/lib/compass-rails.rb#L29) where it is specifically loading the `:assets` group:

```ruby
def load_rails
  return true if rails_loaded?
  return if defined?(::Rails) && ::Rails.respond_to?(:application) && !::Rails.application.nil?

  rails_config_path = Dir.pwd
  until File.exists?(File.join(rails_config_path, 'config', 'application.rb')) do
    raise 'Rails application not found' if rails_config_path == '/'
    rails_config_path = File.join(rails_config_path, '..')
  end
  #load the rails config
  require "#{rails_config_path}/config/application.rb"
  if rails31? || rails32? || rails4?
    require 'sass-rails'
    require 'sprockets/railtie'
    require 'rails/engine'
    @app ||= ::Rails.application.initialize!(:assets) # <---- specifically loading :assets here
  end
end
```

I could be completely off base but that is a little strange.