Developed a MacOS Prefix Mode ASCII Input Source Persistence feature for the ogulcancelik/herdr repository, focusing on enhancing terminal usability for macOS users. The work involved designing a protocol update in Rust to ensure the foreground client automatically switches to an ASCII input source when prefix mode is active, maintaining this state across multi-level prefix commands until returning to the terminal. Leveraging event-driven programming and input handling techniques, the implementation addressed the need for reliable input source switching in the foreground client. This targeted feature improved workflow consistency for users working with complex command sequences, emphasizing protocol design and macOS development expertise.