Nexus Robotics OS is a Rust-first, capability-driven robotics platform designed to provide a stable operating model across simulators, ROS 2 environments, LeRobot workflows, vendor SDKs, and custom hardware adapters. I built the platform around reusable skills, tasks, safety controls, telemetry, replay, simulation, and a shared capability model so software can target robot capabilities rather than individual brands. The project includes a CLI, runtime, simulator, integration SDKs, fleet tooling, deterministic safety mechanisms, and a modular architecture for heterogeneous robotics hardware. The current release is simulation-first and explicitly separates software/simulation validation from physical-robot and hardware-in-the-loop validation.