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

# UserOperation

> ERC-4337 user operation structure (v0.6)

# UserOperation

UserOperation represents an ERC-4337 v0.6 user operation. User operations enable account abstraction by separating transaction validation from execution, allowing smart contract wallets with custom logic for signatures, gas payment, and access control.

## Quick Start

```typescript theme={null}
import { UserOperation } from '@tevm/voltaire/primitives/UserOperation';
import { ENTRYPOINT_V06 } from '@tevm/voltaire/primitives/EntryPoint';

// Create user operation
const userOp = UserOperation.from({
  sender: "0x742d35Cc6634C0532925a3b844Bc9e7595f251e3",
  nonce: 0n,
  initCode: "0x", // Empty if account exists
  callData: "0x...", // Call to execute
  callGasLimit: 100000n,
  verificationGasLimit: 200000n,
  preVerificationGas: 50000n,
  maxFeePerGas: 1000000000n,
  maxPriorityFeePerGas: 1000000000n,
  paymasterAndData: "0x", // Empty if self-paying
  signature: "0x", // Add after signing
});

// Hash for signing
const hash = UserOperation.hash(userOp, ENTRYPOINT_V06, 1);

// Pack to v0.7 format
const packed = UserOperation.pack(userOp);
```

## Type Definition

```typescript theme={null}
export type UserOperationType = {
  readonly sender: AddressType;
  readonly nonce: Uint256Type;
  readonly initCode: Uint8Array;
  readonly callData: Uint8Array;
  readonly callGasLimit: Uint256Type;
  readonly verificationGasLimit: Uint256Type;
  readonly preVerificationGas: Uint256Type;
  readonly maxFeePerGas: Uint256Type;
  readonly maxPriorityFeePerGas: Uint256Type;
  readonly paymasterAndData: Uint8Array;
  readonly signature: Uint8Array;
} & { readonly [brand]: "UserOperation" };
```

## Fields

### sender

Smart account address initiating the operation.

### nonce

Anti-replay nonce. Often encoded as `key || sequence` where:

* `key`: High 192 bits - nonce key for parallel operations
* `sequence`: Low 64 bits - sequential counter per key

### initCode

Account creation code (factory address + calldata). Empty if account already deployed.

### callData

Calldata to execute on the account contract.

### callGasLimit

Gas limit for the execution phase (after validation).

### verificationGasLimit

Gas limit for the validation phase (signature verification).

### preVerificationGas

Fixed gas overhead for bundler compensation (calldata costs, loop overhead).

### maxFeePerGas

Maximum total fee per gas (EIP-1559 format).

### maxPriorityFeePerGas

Maximum priority fee per gas (EIP-1559 tip).

### paymasterAndData

Paymaster address (20 bytes) + paymaster-specific data. Empty if self-paying.

### signature

Account signature over the userOpHash.

## API Reference

### from

Create UserOperation from parameters.

```typescript theme={null}
function from(params: {
  sender: AddressType | string | number | bigint | Uint8Array;
  nonce: Uint256Type | bigint | number | string;
  initCode: Uint8Array | string;
  callData: Uint8Array | string;
  callGasLimit: Uint256Type | bigint | number | string;
  verificationGasLimit: Uint256Type | bigint | number | string;
  preVerificationGas: Uint256Type | bigint | number | string;
  maxFeePerGas: Uint256Type | bigint | number | string;
  maxPriorityFeePerGas: Uint256Type | bigint | number | string;
  paymasterAndData: Uint8Array | string;
  signature: Uint8Array | string;
}): UserOperationType
```

### hash

Compute userOpHash for signing.

```typescript theme={null}
function hash(
  userOp: UserOperationType,
  entryPoint: AddressType | string | number | bigint | Uint8Array,
  chainId: bigint | number
): Uint8Array
```

Formula: `keccak256(abi.encode(userOp, entryPoint, chainId))`

### pack

Convert UserOperation (v0.6) to PackedUserOperation (v0.7).

```typescript theme={null}
function pack(userOp: UserOperationType): PackedUserOperationType
```

## User Operation Lifecycle

1. **Creation**: Wallet creates unsigned user operation
2. **Gas estimation**: Bundler simulates and estimates gas
3. **Signing**: Wallet signs userOpHash
4. **Submission**: Submit to bundler mempool
5. **Bundling**: Bundler aggregates operations
6. **Execution**: EntryPoint validates and executes

## Usage Patterns

### Basic Operation

```typescript theme={null}
import { UserOperation } from '@tevm/voltaire/primitives/UserOperation';
import { ENTRYPOINT_V06 } from '@tevm/voltaire/primitives/EntryPoint';

const userOp = UserOperation.from({
  sender: smartAccountAddress,
  nonce: await account.getNonce(),
  initCode: "0x",
  callData: encodeFunctionData({
    abi: accountAbi,
    functionName: "execute",
    args: [targetAddress, value, data],
  }),
  callGasLimit: 100000n,
  verificationGasLimit: 200000n,
  preVerificationGas: 50000n,
  maxFeePerGas: baseFee + priorityFee,
  maxPriorityFeePerGas: priorityFee,
  paymasterAndData: "0x",
  signature: "0x",
});

// Sign
const hash = UserOperation.hash(userOp, ENTRYPOINT_V06, chainId);
const signature = await account.signMessage(hash);
const signedUserOp = { ...userOp, signature };

// Submit to bundler
await bundler.request({
  method: "eth_sendUserOperation",
  params: [signedUserOp, ENTRYPOINT_V06],
});
```

### With Paymaster

```typescript theme={null}
import { UserOperation } from '@tevm/voltaire/primitives/UserOperation';
import { Paymaster } from '@tevm/voltaire/primitives/Paymaster';

const paymaster = Paymaster.from(paymasterAddress);
const paymasterAndData = new Uint8Array([
  ...paymaster,
  // ...paymasterData
]);

const userOp = UserOperation.from({
  sender: smartAccountAddress,
  // ... other fields
  paymasterAndData,
  signature: "0x",
});
```

### Account Deployment

```typescript theme={null}
import { UserOperation } from '@tevm/voltaire/primitives/UserOperation';

// initCode = factoryAddress (20 bytes) + factoryCalldata
const factoryCalldata = encodeFunctionData({
  abi: factoryAbi,
  functionName: "createAccount",
  args: [owner, salt],
});

const initCode = concat([factoryAddress, factoryCalldata]);

const userOp = UserOperation.from({
  sender: predictedAccountAddress,
  nonce: 0n, // First operation
  initCode, // Deploy account
  callData: "0x", // No execution yet
  // ... gas fields
  signature: "0x",
});
```

## Related Types

* [UserOperation (Effect)](https://voltaire-effect.tevm.sh/primitives/user-operation) - Effect.ts integration with Schema validation
* [PackedUserOperation](/primitives/packed-user-operation) - v0.7 packed format
* [EntryPoint](/primitives/entry-point) - Entry point contract
* [Paymaster](/primitives/paymaster) - Gas sponsorship
* [Bundler](/primitives/bundler) - Operation bundler

## References

* [ERC-4337 Specification](https://eips.ethereum.org/EIPS/eip-4337)
* [Entry Point v0.6](https://github.com/eth-infinitism/account-abstraction/tree/v0.6.0)