Aggregator Batch Router API

The Aggregator Batch Router executes multi-hop swaps across multiple pools and tokens for contract callers such as aggregators, solvers, and smart wallets. It is the prepaid counterpart to the Batch Router: instead of pulling input tokens through Permit2, the caller transfers them to the Vault before invoking the swap, and the router settles that payment. See Token Approvals for how the prepaid and Permit2 models compare.

Paying the Vault

The caller transfers the input tokens to the Vault in the same transaction, before the router runs; the Vault's settlement accounting reverts the swap if the prepayment is insufficient. Unlike the retail Batch Router these functions take no wethIsEth flag, and the router does not use Permit2 (getPermit2 returns the zero address). The permitBatchAndCall and multicall approval helpers inherited from the shared router base are not usable on this prepaid router.

State-changing functions

`swapExactIn`

function swapExactIn(
    SwapPathExactAmountIn[] memory paths,
    uint256 deadline,
    bytes calldata userData
)
    external
    payable
    returns (uint256[] memory pathAmountsOut, address[] memory tokensOut, uint256[] memory amountsOut);

Executes a swap involving multiple paths (steps), specifying exact input token amounts. Each path is independent and can have multiple hops. The caller must have transferred each path's input token to the Vault before this call.

Example: Swap USDC → DAI → WETH in one path, and USDC → USDT → WETH in another path, all in one transaction.

Parameters:

Name	Type	Description
paths	SwapPathExactAmountIn[] memory	Swap paths from token in to token out, specifying exact amounts in
deadline	uint256	Deadline for the swap, after which it will revert
userData	bytes calldata	Additional (optional) data required for the swap

Returns:

Name	Type	Description
pathAmountsOut	uint256[] memory	Calculated amounts of output tokens corresponding to the last step of each given path
tokensOut	address[] memory	Output token addresses
amountsOut	uint256[] memory	Calculated amounts of output tokens, ordered by output token address

`swapExactOut`

function swapExactOut(
    SwapPathExactAmountOut[] memory paths,
    uint256 deadline,
    bytes calldata userData
) external payable returns (uint256[] memory pathAmountsIn, address[] memory tokensIn, uint256[] memory amountsIn);

Executes a swap involving multiple paths (steps), specifying exact output token amounts. The caller funds the Vault with each path's input token, up to the path's maxAmountIn, before this call.

Parameters:

Name	Type	Description
paths	SwapPathExactAmountOut[] memory	Swap paths from token in to token out, specifying exact amounts out
deadline	uint256	Deadline for the swap, after which it will revert
userData	bytes calldata	Additional (optional) data required for the swap

Returns:

Name	Type	Description
pathAmountsIn	uint256[] memory	Calculated amounts of input tokens corresponding to the first step of each given path
tokensIn	address[] memory	Input token addresses
amountsIn	uint256[] memory	Calculated amounts of input tokens, ordered by input token address

Queries

Query functions simulate a swap against current on-chain state without executing it or moving any tokens, so they require no prepayment and no approvals.

`querySwapExactIn`

function querySwapExactIn(
    SwapPathExactAmountIn[] memory paths,
    address sender,
    bytes calldata userData
) external returns (uint256[] memory pathAmountsOut, address[] memory tokensOut, uint256[] memory amountsOut);

Simulates swapExactIn without executing it.

Parameters:

Name	Type	Description
paths	SwapPathExactAmountIn[] memory	Swap paths from token in to token out, specifying exact amounts in
sender	address	The sender passed to the operation. It can influence results (e.g., with user-dependent hooks)
userData	bytes calldata	Additional (optional) data required for the query

Returns:

Name	Type	Description
pathAmountsOut	uint256[] memory	Calculated amounts of output tokens corresponding to the last step of each given path
tokensOut	address[] memory	Calculated output token addresses
amountsOut	uint256[] memory	Calculated amounts of output tokens, ordered by output token address

`querySwapExactOut`

function querySwapExactOut(
    SwapPathExactAmountOut[] memory paths,
    address sender,
    bytes calldata userData
) external returns (uint256[] memory pathAmountsIn, address[] memory tokensIn, uint256[] memory amountsIn);

Simulates swapExactOut without executing it.

Parameters:

Name	Type	Description
paths	SwapPathExactAmountOut[] memory	Swap paths from token in to token out, specifying exact amounts out
sender	address	The sender passed to the operation. It can influence results (e.g., with user-dependent hooks)
userData	bytes calldata	Additional (optional) data required for the query

Returns:

Name	Type	Description
pathAmountsIn	uint256[] memory	Calculated amounts of input tokens corresponding to the first step of each given path
tokensIn	address[] memory	Calculated input token addresses
amountsIn	uint256[] memory	Calculated amounts of input tokens, ordered by input token address

Data Structures

These are the same path structures used by the Batch Router.

`SwapPathStep`

struct SwapPathStep {
    address pool;        // Pool to swap through
    IERC20 tokenOut;     // Token to receive from this step
    bool isBuffer;       // If true, use ERC4626 buffer instead of pool
}

Defines a single step in a swap path.

Fields:

Name	Type	Description
pool	address	Address of the pool to swap through
tokenOut	IERC20	Token to receive from this step
isBuffer	bool	If true, the "pool" is an ERC4626 Buffer used to wrap/unwrap tokens if the pool doesn't have enough liquidity

`SwapPathExactAmountIn`

struct SwapPathExactAmountIn {
    IERC20 tokenIn;             // Starting token
    SwapPathStep[] steps;       // Swap steps to execute
    uint256 exactAmountIn;      // Exact amount to send
    uint256 minAmountOut;       // Minimum amount to receive
}

Defines a swap path with an exact input amount.

Fields:

Name	Type	Description
tokenIn	IERC20	Starting token for this path
steps	SwapPathStep[]	Array of swap steps to execute
exactAmountIn	uint256	Exact amount of tokenIn to send
minAmountOut	uint256	Minimum amount of final output token to receive (slippage protection)

`SwapPathExactAmountOut`

struct SwapPathExactAmountOut {
    IERC20 tokenIn;             // Starting token
    SwapPathStep[] steps;       // Swap steps to execute
    uint256 maxAmountIn;        // Maximum amount to send
    uint256 exactAmountOut;     // Exact amount to receive
}

Defines a swap path with an exact output amount.

Fields:

Name	Type	Description
tokenIn	IERC20	Starting token for this path
steps	SwapPathStep[]	Array of swap steps to execute
maxAmountIn	uint256	Maximum amount of tokenIn to send (slippage protection)
exactAmountOut	uint256	Exact amount of final output token to receive

# Aggregator Batch Router API

# State-changing functions

# swapExactIn

# swapExactOut

# Queries

# querySwapExactIn

# querySwapExactOut

# Data Structures

# SwapPathStep

# SwapPathExactAmountIn

# SwapPathExactAmountOut

Aggregator Batch Router API

State-changing functions

`swapExactIn`

`swapExactOut`

Queries

`querySwapExactIn`

`querySwapExactOut`

Data Structures

`SwapPathStep`

`SwapPathExactAmountIn`

`SwapPathExactAmountOut`