> ## 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.

# Vault

> TypeScript utilities for integrating CoW Protocol with Balancer Vault

# Vault

The Vault module provides utilities for integrating CoW Protocol with Balancer Vault, enabling advanced trading features like internal balance usage and batch swaps.

## Constants

### VAULT\_INTERFACE

A partial ABI interface for the Balancer Vault containing methods for `manageUserBalance` and `batchSwap`:

```typescript theme={null}
const VAULT_INTERFACE: Interface;
```

### Key Addresses (Mainnet)

| Contract                   | Address                                      |
| -------------------------- | -------------------------------------------- |
| Balancer Vault             | `0xBA12222222228d8Ba445958a75a0704d566BF2C8` |
| CoW Protocol Vault Relayer | `0xC92E8bdf79f0507f65a392b0ab4667716BFE0110` |

## Functions

### grantRequiredRoles

Grants necessary permissions to the CoW Protocol Vault Relayer.

```typescript theme={null}
async function grantRequiredRoles(
  vault: Contract,
  vaultRelayerAddress: string
): Promise<void>;
```

<Warning>
  This function is intended to be called by the Balancer Vault admin, **not** by traders.
</Warning>

## Balance Types

Users can configure token handling through three balance types:

| Type         | Description                                 | Gas Cost |
| ------------ | ------------------------------------------- | -------- |
| **ERC20**    | Standard transfers requiring token approval | Standard |
| **EXTERNAL** | Leverages existing Vault approvals          | Reduced  |
| **INTERNAL** | Uses Vault internal balances                | Lowest   |

## Example

```typescript theme={null}
import { ethers } from "ethers";

const provider = new ethers.providers.JsonRpcProvider("YOUR_RPC_URL");

// Balancer Vault on mainnet
const vaultAddress = "0xBA12222222228d8Ba445958a75a0704d566BF2C8";
const vaultRelayer = "0xC92E8bdf79f0507f65a392b0ab4667716BFE0110";

// Check internal balance
const vault = new ethers.Contract(vaultAddress, VAULT_INTERFACE, provider);
```

<Warning>
  On networks where the Balancer Vault contract has a known compromised admin key (notably Ethereum mainnet, Gnosis Chain, Arbitrum, and Base), using `INTERNAL` or `EXTERNAL` balance types may expose users to risk. The CoW Protocol API rejects orders using these balance types on affected networks. Always use `ERC20` balance type unless you have verified that the Balancer Vault on your target network is safe (e.g., Plasma, which uses a non-compromised deployment).
</Warning>

<Tip>
  Internal balance operations have different gas cost characteristics than standard ERC20 transfers. Test thoroughly on testnets before using Vault integration in production.
</Tip>