In the current implementation, when running parallel Test steps with TI enabled, the harness_ruby_agent gem is added to the Gemfile multiple times. This occurs because the Gemfile is shared across parallel steps, and each step adds the gem individually.

To address this, we propose an enhancement to check the Gemfile for an existing harness_ruby_agent gem declaration before adding it. This will prevent duplicate entries and ensure the gem is only added if it's not already present.

This enhancement will improve the handling of Gemfiles when running parallel Test steps in TI.