Conditional Checkout Fields in Magento 2: Show Field A Only When B Is True
Conditional checkout fields are the rule set that says "only show field A when condition B is true", and they look identical on Luma and Hyvä until you try to ship one. This is the production recipe for three real rules on both stacks: a Knockout subscribe on Luma, a Magewire $reactive plus Alpine x-show on Hyvä, plus the quote_extension_attributes wiring that keeps the value alive across page reload and 3DS redirect. The three rules ship together in roughly 38 hours on Magento 2.4.4-2.4.9 with Hyvä Checkout 1.1+.