In October 2025, Andrew Schmitz developed the Dynamic Menu Item Management API for the thunderbird/tbpro-add-on repository, enabling dynamic creation, updating, and removal of menu items and submenus within the Thunderbird Pro application. Leveraging JavaScript and JSON, Andrew aligned the API’s architecture with Thunderbird’s app-menu system to support extensibility and future partner integrations. The implementation included an experiment flag to measure menu customization usage, laying the foundation for persistent menu items and future feature expansion. This work focused on API development and front end engineering, providing a flexible, experiment-ready surface for UI customization and rapid iteration in the application menu.