Verify Checkout

Verify the payer's on-chain transaction and mark the payment link paid.

The payer must have sent exactly the required amount to the receiver address on the correct chain. The facilitator performs the on-chain verification.

Returns the redirect_url on success so the browser JS can redirect. Returns 422 if the transaction is invalid or cannot be verified. Returns 409 if the link is already paid. Returns 410 if the link is expired or cancelled.