> ## 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.

# Contracts

> TypeScript utilities for interacting with CoW Protocol smart contracts, encoding settlements, and managing orders

# @cowprotocol/sdk-contracts-ts

## Overview

The `@cowprotocol/sdk-contracts-ts` package provides TypeScript utilities for interacting with CoW Protocol smart contracts, encoding settlements, and managing orders.

## Installation

```bash theme={null}
npm install @cowprotocol/sdk-contracts-ts
```

## Core Data Structures

### Order Interface

Orders represent Gnosis Protocol v2 transactions with fields for token pairs, amounts, validity periods, and execution parameters. Key properties include `sellToken`, `buyToken`, `sellAmount`, `buyAmount`, `validTo`, `appData`, `feeAmount`, `kind`, and balance management options.

### OrderKind Enum

Two types exist:

* `SELL` - selling a specific token amount
* `BUY` - buying a specific token amount

### OrderBalance Enum

Balance management strategies:

* `ERC20` - standard ERC-20 balances
* `EXTERNAL` - Balancer Vault external balances
* `INTERNAL` - Balancer Vault internal balances

## Signing Schemes

Four signing methods are supported:

| Scheme  | Value | Purpose                        |
| ------- | ----- | ------------------------------ |
| EIP712  | 0b00  | EIP-712 typed data (preferred) |
| ETHSIGN | 0b01  | eth\_sign RPC calls            |
| EIP1271 | 0b10  | Smart contract signatures      |
| PRESIGN | 0b11  | Pre-signed orders              |

## Utility Functions

### hashOrder

Generates a 32-byte signing digest for orders using EIP-712 domain separators.

### computeOrderUid

Creates a unique 56-byte identifier combining order hash, owner address, and validity time.

### extractOrderUidParams

Reverses UIDs into component parts (digest, owner, validTo).

### normalizeOrder

Prepares order data for cryptographic signing operations.

## Settlement Encoding

### SettlementEncoder Class

Primary class managing settlement construction through:

* `encodeTrade()` - adds trades with signatures
* `signEncodeTrade()` - signs and encodes trades atomically
* `encodeInteraction()` - includes contract interactions
* `encodedSettlement()` - generates final encoded output

### InteractionStage Enum

Execution timing for contract interactions:

* `PRE` (0) - approvals and permits
* `INTRA` (1) - AMM interactions
* `POST` (2) - cleanup operations

## Trade & Flag Encoding

Trade data includes token indices, execution amounts, and bitfield flags. The `encodeTradeFlags()` function converts flag objects into numeric representations, while `decodeTradeFlags()` reverses this process.

## Order Cancellation

Functions handle single and batch order cancellations:

* `hashOrderCancellation()` - single order
* `hashOrderCancellations()` - multiple orders

## Constants

Key values include:

* `BUY_ETH_ADDRESS` = `0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE` (ETH marker)
* `ORDER_UID_LENGTH` = 56 bytes
* `ORDER_TYPE_HASH` for EIP-712 compliance

## Package Version

Access via:

```typescript theme={null}
import { CONTRACTS_PKG_VERSION } from '@cowprotocol/sdk-contracts-ts'
```