ISwapGuard

API reference for the ISwapGuard interface that enables order settlement restrictions in ComposableCoW.

ISwapGuard

The ISwapGuard interface enables CoW Protocol to restrict order settlements through ComposableCoW by implementing a verification mechanism.

Core Function

The interface requires a single verify() function that evaluates whether an order meets security criteria before settlement. This function receives:

Parameter	Type	Description
order	GPv2Order.Data	The CoW Protocol order data
ctx	bytes32	Context identifier (either bytes32(0) for merkle trees or a hash for cabinet lookups)
params	ConditionalOrderParams	Programmatic order parameters
offchainInput	bytes	Optional off-chain verification input

The function returns a boolean indicating approval.

Implementation Examples

ReceiverLock

Restricts orders to self-transfers only, preventing fund redirection by ensuring the receiver is set to address(0).

TokenWhitelistGuard

Maintains an approved token list, validating both the sell and buy tokens against this whitelist.

AmountLimitGuard

Enforces maximum trade sizes by checking the sell amount against a configured limit.

Key Requirements

• Implementations should inherit from BaseSwapGuard for proper ERC-165 interface support
• Verification logic must remain stateless, deterministic, and gas-efficient since it executes during order validation

Guards represent security-critical components requiring thorough testing before production deployment. Guards cannot prevent malicious order handlers from being used.