If I decide to add it, which solution should I pick, battle tested Sorbet or core team endorsed RBS?

Passing the class prop to the root dom element is already a wide spread practice

It's a convention in Svelte to export { className as class } inspired from docs, but it's certainly not required by the compiler, so I don't think the class:directive can/should be assumed here.

On the one hand, it's an unofficial but widely-used practice to do let classNames=''; export { classNames as class }; in components and then apply that class on the top-level DOM element in the component. On the other hand, there are plenty of components out there that don't use this idiom