Ona is a software system designed to enhance productivity by facilitating parallel work and minimizing cognitive load in AI-assisted environments. It challenges traditional software engineering practices, which emphasize singular focus, by encouraging multitasking through a redesigned interface that reduces the cost of context switching and enables users to monitor and manage multiple tasks simultaneously. Features such as a persistent sidebar provide real-time updates on task progress, while an integrated conversation view offers detailed insights into current and past agent activities. Ona's design, influenced by the principle that plans are resources for situated action, focuses on flexibility and collaboration rather than rigid execution, allowing users to adapt workflows dynamically via tools like TODOs and slash commands. Additionally, the system prioritizes user control and minimizes risk through mechanisms like isolated environments, an emergency stop button, and frequent commits, ensuring a balance between innovation and security. Ultimately, Ona aims to amplify the user's ability to work efficiently with AI by offering a streamlined, intuitive interface that supports parallel workstreams without overwhelming the user.