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Pre Confirmations

Icon LinkPre-Confirmations

Icon LinkWhat is a Pre-Confirmation?

A pre-confirmation is an intermediate transaction status that occurs after a transaction has been submitted and accepted by the blockchain, but before it is fully processed and included in a new block.

At this stage, the transaction is pre-executed and assigned one of two possible statuses:

  • PreconfirmationSuccessStatus: The transaction is expected to be successfully included in a future block.

  • PreconfirmationFailureStatus: The transaction will not be included in any future block.

Icon LinkWhy are Pre-Confirmations important?

Pre-confirmations allow applications to react earlier by providing immediate feedback about a transaction's expected outcome without waiting for full block finalization.

Additionally, pre-confirmations expose processed outputs (such as OutputChange and OutputVariable) that can be immediately reused in new transactions.

Icon LinkAvailable Outputs for Pre-Confirmations

When a transaction reaches the pre-confirmation stage, certain resolvedOutputs become available:

  • OutputChange: Represents the change UTXO generated from unspent inputs, grouped by assetId (one per asset).

  • OutputVariable: Similar to OutputCoin, but only created if the transaction succeeds.

These outputs can be:

  • Extracted directly from the pre-confirmation response.
  • Used immediately to fund new transactions, without waiting for block confirmation.

This significantly improves the ability to build transaction sequences or reactive transaction flows.

This is the ResolvedOutput interface structure: 

export type ResolvedOutput = {
  utxoId: string;
  output: OutputChange | OutputVariable;
};

Icon LinkExample Workflow

Suppose you send a transaction that will send funds to another wallet.

As soon as you receive a PreconfirmationSuccessStatus, you can:

  • Use the OutputChange in a new transaction.
  • Submit the next transaction without waiting for block finalization.

This reduces wait times and accelerates transaction chaining.

Icon LinkCode Examples

Icon LinkUsing Pre-Confirmations when Submitting a Transfer

The following example sends a transfer, waits for the pre-confirmation success, and then submits another transfer using the resolved outputs from the first: 

const provider = new Provider(LOCAL_NETWORK_URL);
 
const wallet = Wallet.fromPrivateKey(WALLET_PVT_KEY, provider);
const recipient1 = Wallet.fromPrivateKey(WALLET_PVT_KEY_2, provider);
const recipient2 = Wallet.fromPrivateKey(WALLET_PVT_KEY_3, provider);
const baseAssetId = await provider.getBaseAssetId();
 
// Send a transfer and retrieve the pre-confirmation callback
const { waitForPreConfirmation } = await wallet.transfer(
  recipient1.address,
  1000
);
 
// Wait for the transaction to reach a pre-confirmation status
const { resolvedOutputs, isStatusPreConfirmationSuccess } =
  await waitForPreConfirmation();
 
// Check if the pre-confirmation status indicates success
if (isStatusPreConfirmationSuccess) {
  // Find the change output associated with the base asset ID
  const resolvedChangeOutput = resolvedOutputs?.find(
    (resolved) =>
      resolved.output.type === OutputType.Change &&
      resolved.output.assetId === baseAssetId
  );
 
  // If we find the change output, we can use it to create a new transaction
  if (resolvedChangeOutput) {
    const { output, utxoId } = resolvedChangeOutput;
 
    // Create a new transaction request
    const newTransaction = new ScriptTransactionRequest({
      maxFee: 1000,
      gasLimit: 1000,
    });
 
    // Add the change output as an input resource for the new transaction
    newTransaction.addResource({
      id: utxoId,
      assetId: output.assetId,
      amount: output.amount,
      owner: new Address(output.to),
      blockCreated: bn(0),
      txCreatedIdx: bn(0),
    });
 
    // Define the transfer recipient of the new transaction
    newTransaction.addCoinOutput(recipient2.address, 1000, baseAssetId);
 
    // Send the new transaction
    await wallet.sendTransaction(newTransaction);
  }
}

Icon LinkUsing Pre-Confirmations with a Contract Call

This example performs a contract call, waits for pre-confirmation success, and then uses the resolved output to execute another contract call: 

// Send a contract call and retrieve the pre-confirmation callback
const { waitForPreConfirmation } = await contract.functions
  .increment_count(1)
  .call();
 
const {
  transactionResult: { resolvedOutputs, isStatusPreConfirmationSuccess },
} = await waitForPreConfirmation();
 
// Check if the pre-confirmation status indicates success
if (isStatusPreConfirmationSuccess) {
  // Find the change output associated with the base asset ID
  const resolvedChangeOutput = resolvedOutputs?.find(
    (resolved) =>
      resolved.output.type === OutputType.Change &&
      resolved.output.assetId === baseAssetId
  );
 
  // If we find the change output, we can use it to create a new transaction
  if (resolvedChangeOutput) {
    const { output, utxoId } = resolvedChangeOutput;
 
    // Create a new transaction request for a new contract call
    const request = await contract.functions
      .increment_count(1)
      .txParams({
        maxFee: 100_000,
        gasLimit: 100_000,
      })
      .getTransactionRequest();
 
    // Add the change output as an input resource for the new transaction
    request.addResource({
      id: utxoId,
      assetId: output.assetId,
      amount: output.amount,
      owner: new Address(output.to),
      blockCreated: bn(0),
      txCreatedIdx: bn(0),
    });
 
    // Send the new transaction
    await wallet.sendTransaction(request);
  }
}