Definition
A Hyvä compatibility module is an adapter package that re-implements a third-party Magento extension's frontend under Hyvä (Alpine.js + Tailwind) so the extension's logic continues to work but its visible output renders the Hyvä way. Without one, most Luma-only extensions are silent under Hyvä.
Why every paid extension needs Hyvä compatibility
Most Magento extensions written for Luma target Knockout templates and the Magento UI Component system — neither of which exists under Hyvä. The extension's backend logic still runs (admin config, observers, events) but the frontend output is silent: the user sees nothing where the extension was supposed to render.
Where Hyvä compatibility modules come from
Three sources: (1) the extension vendor publishes their own — increasingly common, growing list at compat.hyva.io; (2) the open-source Hyvä community contributes one for a widely-used extension; (3) a custom compatibility module is built by your dev team or your Hyvä agency, usually a 1-3 week piece of work per extension.
What a compatibility module actually does
It shadows the extension's frontend touch points (Magento layout XML, .phtml templates, UI Component JS) and provides Hyvä-native equivalents under Tailwind + Alpine. Magic strings and event dispatchers are preserved so admin configuration carries over unchanged. The pattern is documented in the Hyvä compatibility module guide on docs.hyva.io.