Peacemaker - The Revelations Cycle, #6

Peacemakers. The Galactic Union's most capable enforcers and resolute negotiators, their name alone elicits fear and awe among the Union's citizenry. Having completed a harrowing confirmation mission, Jessica Francis stands ready to become Earth's first Peacemaker and believes obtaining her commission is a mere formality. However, certain members of the Guild question her ability. Worried that she'll fall back on her mercenary ways, they want Jessica to prove her mettle at the negotiating table before she puts on the distinctive insignia of a Peacemaker. Dream Worlds are terraformed planets inhabited by multiple species living and working in harmony.
Operated by a governing Consortium, each carefully-controlled world is marketed as a paradise, but Araf is far from. The conditions are deplorable, and its three colonies are moving relentlessly toward all-out war over scarce resources and broken promises. A three-way showdown for dominance looms-can Jessica prevent war and bring back peace? One thing is certain; she's never walked away from a fight, and she's not going to start now.