Palette
Five to twelve colours. The centre tone is the colour the theme is built around; the darkest one paints the dark frame. Each colour is a seed: the engine derives every surface and word from them.
Prove and propose
The proof holds the palette to every rule the package's own palettes are held to, over every combination a person could reach (four light levels, contrasts, materials, colour amounts, frames, both markers). It takes a few seconds.
Proposing opens the file on GitHub, signed in as you, as a new pull request to catalogue/palettes/. CI proves it again; once merged, every app that loads the catalogue offers it, without a deploy of its own.