Books like The Ember War

Earth is doomed. Humanity has a chance. In the near future, an alien probe arrives on Earth with a pivotal mission—help humanity survive an impending invasion by an alien armada so massive it can blot out the stars, or leave the human race to certain extinction. Despite overwhelming odds, the probe recruits a young inventor named Marc Ibarra to plan a daring gambit. To weather the coming storm, Ibarra must build a space fleet strong enough to face an implacable foe in a battle against annihilation.