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Abstract Interface Class Interface for apps to provide crypto wallet signing capabilities. 
abstract interface class CrossmintCheckoutPayer
When crypto payments are enabled in the checkout, the hosted page will request transaction signing via postMessage. The app implements this interface to bridge to its wallet. Prefer attaching the payer under payment.crypto.payer in CrossmintCheckoutConfig. The widget-level CrossmintEmbeddedCheckout.payer override is retained for compatibility.

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Properties

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address

String get address
Current wallet address.

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initialChain

String get initialChain
Chain the wallet is initially connected on.

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supportedChains

List<String> get supportedChains
Chains the wallet can sign transactions on. The hosted checkout only offers chains that appear here.

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walletProviderKey

String? get walletProviderKey
Optional wallet provider identifier (e.g. “metamask”, “coinbase”). Returns null if not applicable.

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Methods

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signAndSendTransaction

Future<CrossmintCheckoutTransactionResult> signAndSendTransaction(
  String serializedTransaction,
)
Signs and broadcasts a serialized transaction. Return CrossmintCheckoutTransactionSuccess with the transaction id on success, or CrossmintCheckoutTransactionFailure with a user-facing message on failure.

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switchChain

Future<void> switchChain(String chain)
Switches the wallet to chain. Called by the hosted page when the user changes chain in the UI.

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signMessage

Future<String>? signMessage(String message)
Optional — return null if message signing is not supported.