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

# GPv2Settlement API

> Core settlement contract API for executing batch trades in Gnosis Protocol v2

# GPv2Settlement API

The core settlement contract for executing batch trades in Gnosis Protocol v2.

**Inherits:** `GPv2Signing`, `ReentrancyGuard`, `StorageAccessible`

## State Variables

```solidity theme={null}
GPv2Authentication public immutable authenticator;
IVault public immutable vault;
GPv2VaultRelayer public immutable vaultRelayer;
mapping(bytes => uint256) public filledAmount;
```

## Events

```solidity theme={null}
event Trade(
    address indexed owner,
    IERC20 sellToken,
    IERC20 buyToken,
    uint256 sellAmount,
    uint256 buyAmount,
    uint256 feeAmount,
    bytes orderUid
);

event Interaction(address indexed target, uint256 value, bytes4 selector);

event Settlement(address indexed solver);

event OrderInvalidated(address indexed owner, bytes orderUid);
```

## Functions

### settle

Executes a batch settlement with uniform clearing prices.

```solidity theme={null}
function settle(
    IERC20[] calldata tokens,
    uint256[] calldata clearingPrices,
    GPv2Trade.Data[] calldata trades,
    GPv2Interaction.Data[][3] calldata interactions
) external nonReentrant onlySolver;
```

**Parameters:**

| Name             | Type                        | Description                                                |
| ---------------- | --------------------------- | ---------------------------------------------------------- |
| `tokens`         | `IERC20[]`                  | Array of tokens involved in the settlement                 |
| `clearingPrices` | `uint256[]`                 | Clearing prices for each token (aligned with tokens array) |
| `trades`         | `GPv2Trade.Data[]`          | Encoded trade data                                         |
| `interactions`   | `GPv2Interaction.Data[][3]` | Pre, intra, and post-settlement interactions               |

### swap

Matches an order directly against a Balancer V2 pool.

```solidity theme={null}
function swap(
    IVault.SingleSwap calldata singleSwap,
    GPv2Trade.Data calldata trade
) external nonReentrant onlySolver returns (int256);
```

### invalidateOrder

Allows order owners to cancel orders on-chain.

```solidity theme={null}
function invalidateOrder(bytes calldata orderUid) external;
```

### freeFilledAmountStorage

Frees storage for filled orders to claim gas refunds.

```solidity theme={null}
function freeFilledAmountStorage(bytes[] calldata orderUids) external;
```

### freePreSignatureStorage

Frees storage for pre-signed orders to claim gas refunds.

```solidity theme={null}
function freePreSignatureStorage(bytes[] calldata orderUids) external;
```

## Price Validation

The contract enforces that clearing prices respect order limits:

```
order.sellAmount * sellPrice >= order.buyAmount * buyPrice
```

This ensures all trades execute at or better than the user's specified limit prices.