> ## Documentation Index
> Fetch the complete documentation index at: https://docs.aeon.so/llms.txt
> Use this file to discover all available pages before exploring further.

# prepareSigning()

> Prepares a previously defined transaction for signing by fetching necessary on-chain data and serializing it via the backend.

# `AeonClient.prepareSigning(params: PrepareSigningParams): AeonClient`

This `AeonClient` method takes a `txId` (identifying a previously defined transaction intent) and a `workspaceId` to specify the context.

This method queues an operation. When `aeonClient.build()` is subsequently called, the backend service will:

1. Retrieve the full transaction details associated with the provided `txId` and `workspaceId`.
2. Ensure all necessary parameters for signing are present and valid. This can involve fetching current on-chain data such as the sender's nonce or prevailing gas prices, especially if these were not finalized in the original transaction intent or need re-validation.
3. Construct and serialize the transaction into a chain-specific signable format.

The `AeonClient` instance is returned to allow for chaining of other operations before calling `build()`.

## Parameters

* `params`: `PrepareSigningParams` - An object containing:
  * `txId`: `string` - The unique identifier of a previously defined or simulated transaction intent. The backend uses this ID to retrieve the transaction details.
  * `workspaceId`: `string` - The identifier of the workspace in which the transaction (`txId`) exists and is being prepared.

## Conceptual Example: `aeonClient.prepareSigning()`

```typescript theme={null}
// Example of queuing a transaction signing preparation
const aeonClient = new AeonClient({ simulationUrl: "..." }); // Backend URL for prepareSigning services

const transactionIdToPrepare = "existing-tx-intent-id-123";
const currentWorkspace = "workspace-main-ops";

aeonClient.prepareSigning({
  txId: transactionIdToPrepare,
  workspaceId: currentWorkspace,
});

// Optionally, chain other operations if needed
// .simulate("evm", { ... }) // etc.

// Later, to process the queue and get the signable transaction data:
// async function getPreparedTransaction() {
//   const buildResult = await aeonClient.build();
//   // The buildResult will contain outputs for each queued operation.
//   // You'll need to find the output corresponding to the prepareSigning call.
//   // Assuming buildResult.outputs is an array in order of queuing:
//   const preparedTxData = buildResult.outputs[0]; // Or find by a unique ID if available

//   if (preparedTxData && preparedTxData.type === "PREPARED_SIGNING_DATA") { // Hypothetical type
//     const txbToSign = preparedTxData.payload.txb_serialized_b64; // Example structure
//     console.log("Transaction ready for signing:", txbToSign);
//     return txbToSign;
//   } else {
//     console.error("Could not find prepared signing data in build result.");
//   }
// }
```