# prepareTransactionForSigning

The `prepareTransactionForSigning` method prepares a Bitcoin transaction for MPC signing by creating a PSBT (Partially Signed Bitcoin Transaction) and computing the hash that needs to be signed.

## Usage

```ts twoslash
// [!include ~/snippets/code/chains.ts]
// ---cut---
const { transaction, hashesToSign } =
  await btcChain.prepareTransactionForSigning({
    from: 'bc1qxy2kgdygjrsqtzq2n0yrf2493p83kkfjhx0wlh',
    to: 'bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4',
    value: '0.001', // 0.001 BTC
    publicKey: '0235a3...',
  })
```

## Parameters

| Parameter            | Type                    | Description                                                                                               |
| -------------------- | ----------------------- | --------------------------------------------------------------------------------------------------------- |
| `transactionRequest` | `BTCTransactionRequest` | The transaction request object containing publicKey and either `{inputs, outputs}` or `{from, to, value}` |

## Returns

| Property       | Type                     | Description                            |
| -------------- | ------------------------ | -------------------------------------- |
| `transaction`  | `BTCUnsignedTransaction` | Object containing the unsigned PSBT    |
| `hashesToSign` | `number[][]`             | Array of hashes that need to be signed |