The post explains how to design an internal API with clear function categories (e.g., signIn/signUp, addProduct/buyProduct) and simple, flat grouping so that each group contains only related functions; it then introduces a permission system where users belong to groups that grant specific rights such as canBuy or canDeleteAccount, and shows how to layer validation rules (StrongPassword, ValidProductID, UnderRateLimit) on top of those API calls. To visualize the whole setup, the author suggests building a âfirewallâlikeâ table that lists all functions with their categories, required permissions, and validation rules, as well as a live dashboard that highlights executed calls in real time (e.g., blinking rows or tick marks). Finally, he recommends adding a âRed Team User Interfaceâ that simulates OWASP attacks to test the systemâs resilience, concluding that creating such tools not only protects code but also deepens understanding and fuels creativity.