The four card types

Every item you create is a card of one of four types: Music (an instrumental style), Vocal (a voice style), Song (a title and lyrics that links one Music and one Vocal style), and Note (free-form text for ideas or references).

Splitting Music and Vocal out from the Song is the whole idea - you build a small library of styles and recombine them across many songs, instead of rewriting a full prompt every time. You pick the type when you create a card, and it decides which fields the editor shows.