Chain Abstraction

Chain Abstraction in WalletKit enables users with stablecoins on any network to spend them on-the-fly on a different network. Our Chain Abstraction solution provides a toolkit for wallet developers to integrate this complex functionality using WalletKit.

For example, when an app requests a 100 USDC payment on Base network but the user only has USDC on Arbitrum, WalletKit offers methods to detect this mismatch, generate necessary transactions, track the cross-chain transfer, and complete the original transaction after bridging finishes.

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How It Works

When sending a transaction, you need to:

1. Check if the required chain has enough funds to complete the transaction
2. If not, use the prepare method to generate necessary bridging transactions
3. Sign routing and initial transaction hashes, prepared by the prepare method
4. Use execute method to broadcast routing and initial transactions and wait for it to be completed

The following sequence diagram illustrates the complete flow of a chain abstraction operation, from the initial dapp request to the final transaction confirmation

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Methods

Following are the methods from WalletKit that you will use in implementing chain abstraction.

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Prepare

This method checks if a transaction requires additional bridging transactions beforehand.

public abstract prepare(params: {
  transaction: ChainAbstractionTypes.PartialTransaction;
}): ChainAbstractionTypes.PrepareResponse;

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Execute

Helper method used to broadcast the bridging and initial transactions and wait for them to be completed.

public abstract execute(params: {
  orchestrationId: ChainAbstractionTypes.OrchestrationId;
  bridgeSignedTransactions: ChainAbstractionTypes.SignedTransaction[];
  initialSignedTransaction: ChainAbstractionTypes.SignedTransaction;
}): ChainAbstractionTypes.ExecuteResult;

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Usage

When sending a transaction, first check if chain abstraction is needed using the prepare method. If it is needed, you must sign all the fulfillment transactions and use the execute method. Here’s a complete example:

// Check if chain abstraction is needed
const result = await walletKit.chainAbstraction.prepare({
  transaction: {
    from: transaction.from as `0x${string}`,
    to: transaction.to as `0x${string}`,
    // @ts-ignore - cater for both input or data
    input: transaction.input || (transaction.data as `0x${string}`),
    chainId: chainId,
  },
});

// Handle the prepare result
if ('success' in result) {
  if ('notRequired' in result.success) {
    // No bridging required, proceed with normal transaction
    console.log('no routing required');
  } else if ('available' in result.success) {
    const available = result.success.available;
    
    // Sign all bridge transactions and initial transaction
    const bridgeTxs = available.route.map(tx => tx.transactionHashToSign);
    const signedBridgeTxs = bridgeTxs.map(tx => wallet.signAny(tx));
    const signedInitialTx = wallet.signAny(available.initial.transactionHashToSign);

    // Execute the chain abstraction
    const result = await walletKit.chainAbstraction.execute({
      bridgeSignedTransactions: signedBridgeTxs,
      initialSignedTransaction: signedInitialTx,
      orchestrationId: available.routeResponse.orchestrationId,
    });
  }
}

For example, check out implementation of chain abstraction in sample wallet built with React.

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Error Handling

When implementing Chain Abstraction, you may encounter different types of errors. Here’s how to handle them effectively:

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Application-Level Errors

These errors (PrepareError) indicate specific issues that need to be addressed and typically require user action:

• Insufficient Gas Fees: User needs to add more gas tokens to their wallet
• Malformed Transaction Requests: Transaction parameters are invalid or incomplete
• Minimum Bridging Amount Not Met: Currently set at $0.60
• Invalid Token or Network Selection: Selected token or network is not supported

When handling these errors, you should display clear, user-friendly error messages that provide specific guidance on how to resolve the issue. Allow users to modify their transaction parameters and consider implementing validation checks before initiating transactions.

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Retryable Errors

These errors (Result::Err) indicate temporary issues that may be resolved by retrying the operation. Examples of these types of issues include network connection timeouts, TLS negotiation issues, service outages, or other transient errors.

For retryable errors, show a generic “oops” message to users and provide a retry button. Log detailed error information to your error tracking service, but avoid displaying technical details to end users.

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Critical Errors

Critical errors indicate bugs or implementation issues that should be treated as high-priority incidents: incorrect usage of WalletKit API, wrong data encoding or wrong fields passed to WalletKit, or WalletKit internal bugs.

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Testing

To test Chain Abstraction, you can use the AppKit laboratory and try sending USDC/USDT with any chain abstraction supported wallet. You can also use this sample wallet for testing.