Traditional CLI development often involves writing repetitive runtime validation logic to manage complex dependencies between various flags and options. While modern TypeScript-first libraries have improved individual option parsing, they frequently fail to encode these inter-dependencies into the type system, resulting in loose types that necessitate manual checks. Optique solves this problem through its conditional combinator, which treats option relationships as a primary architectural concern. By utilizing a discriminator value to select specific branches of a parser, it enables the automatic inference of precise discriminated unions. This ensures that certain flags are strictly required or forbidden based on the values of other options, effectively shifting validation logic from runtime to the compiler. Whether modeling database connection strings or authentication protocols, the structure of the parser serves as the ultimate constraint. This methodology eliminates the need for manual validation code and ensures that the type system remains the single source of truth throughout the application's lifecycle. Embracing structural parsing over manual validation significantly enhances the reliability and maintainability of sophisticated command-line tools.