application_record.rb

class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true

  # This method adds a hidden activerecord relationship.
  #
  # The relationship is hidden as you cannot access them via `model.assocation`, but can be
  # preloaded and can be accessed within specific components by wrapping the model.
  #
  # Use this for associations on models which have been moved under specific components and
  # expose these associations instead in the model itself.
  def self.hide_association(relation, association_name, *args)
    # rubocop:disable GitlabSecurity/PublicSend
    send(relation, association_name, *args)
    # rubocop:enable GitlabSecurity/PublicSend
    undef_method(association_name)
  end
end

bar.rb

class AnotherComponent::Models::Bar < ApplicationRecord
  def self.for(foo_model)
    foo_model.association(:bars).reader
  end
end

# Example usage
SomeComponent::Models::Foo
  .includes(:bars)
  .map { |foo| 
    # This would typically happen somewhere inside AnotherComponent
    AnotherComponent::Models::Bar.for(foo) 
  }

foo.rb

class SomeComponent::Models::Foo < ApplicationRecord
  # Instead of `has_many, :bars, class_name: 'AnotherComponent::Models::Bar'`
  hide_association :has_many, :bars, class_name: 'AnotherComponent::Models::Bar'
end