Upsell Charge By Contact

POST 
/api/forms/public/:form_id/upsell/charge-by-contact

PUBLIC endpoint — one-click upsell charge using the contact's saved cards.

The server tries the contact's saved cards in priority order; if every card declines (or there are no cards on file), the response is {success: false, needs_card: true, missing_fields: [...]} so the upsell page can open the inline retry form that asks only for fields we don't have.

Request​