kiosk-pay-stripe is the open-source Stripe payment adapter for Kiosk. It implements both halves of the provider-acquired, card-on-file model: - Card acquisition. `setup_url(user_id:, return_url:)` returns a hosted Stripe Checkout session in `mode: "setup"` that saves the buyer's card on the PROVIDER's own Stripe account (an existing open setup session is reused, so the url is stable across polls); `setup_required?` tells the wire whether a principal still has to complete it, backed by `saved_method?`, which asks Stripe whether the resolved Customer has a usable card. - Charging. This adapter's own `#capture` settles an AP2 cart mandate as an `off_session` (merchant-initiated) PaymentIntent against that saved card — the assistant authorizes the cart, it never presents a card. The gem stays app-agnostic: the principal-to-Stripe-Customer mapping is injected by the host through `customer_resolver:` / `customer_saver:` callables, and no application table is read inside the gem. Today only kiosk-pay-stripe ships; there is no default PSP (Configuration#payment_provider is nil). A host that needs another PSP subclasses Kiosk::PaymentProviders::Base and assigns the instance to Kiosk.configuration.payment_provider.