The Android Open Harness Project (AOHP) is an open-source operating system-level agent harness built on the Android Open Source Project. It addresses the mismatch between current application-centric operating systems and the needs of autonomous AI agents by treating agents as first-class OS actors. The design introduces three key mechanisms: personalized service composition, efficient agent interfaces, and secure information flow. These features enable adaptive user interfaces and agent-friendly runtime environments while preserving the existing Android ecosystem. Preliminary experiments on challenging tasks demonstrate significant performance improvements over conventional systems. Specifically, AOHP achieved a 21.12% increase in task completion rates compared to baseline methods. It also reduced token execution costs by 51.55%, highlighting its efficiency gains. Furthermore, the system showed improved compliance with security policies during agent-mediated interactions.