Frederick Cheung developed and exported the HeartToolbarItem API for the tldraw/tldraw repository, enabling its integration within the application and supporting future UI customization. He approached the task with a focus on aligning the API surface to match component usage patterns, ensuring backward compatibility and reducing integration friction for downstream features. Working primarily with TypeScript and front end development principles, Frederick carefully managed module boundaries and API exposure to facilitate extensibility. Although the work spanned a single feature over one month, it demonstrated thoughtful API design and laid the groundwork for HeartToolbar-driven enhancements without introducing new bugs or regressions.