Do I need to know Luma before learning Hyvä with Claude Code?

No, and arguably you should skip Luma if you can. Hyvä replaces RequireJS, Knockout, and the layered Luma CSS with Tailwind + Alpine.js, none of the Luma muscle memory transfers. What does transfer: layout XML, blocks, view models, and the ViewModelInterface pattern. Have Claude Code generate a Hyvä block + view-model pair on day 1; if you can read it without help, you have enough Magento context. The Hyvä themes glossary is the fastest catch-up.