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import HistoricalFact from './'



The allow-list authenticator contract determines which addresses are solvers. Before executing any operation which is access-restricted to a solver, the settlement contract queries this contract to determine if the caller is a solver.

The smart contract allows a manager to add or remove solvers with an on-chain transaction. The manager can be replaced in a transaction by the proxy owner or itself. Any of these actions emit the corresponding event.

Guarantees and Invariants

  • Only the manager or the owner can change the manager
  • Only the manager can add or remove solvers

As this contract is deployed with a proxy pattern, these guarantees are only valid for the current implementation of the contract. If the contract is upgraded, these guarantees may not hold.

Any malicious actor with access to the manager may be able to introduce a malicious solver. The malicious solver may be able to steal funds from the settlement contract (i.e. CoW Protocol), however, this does NOT affect user funds.

Data Types and Storage


The manager is the address that can add or remove solvers.

address public manager;


The solvers mapping stores whether an address is a solver.

mapping(address => bool) private solvers;

The solvers mapping is private, but it is exposed through the isSolver function.


For owner or manager


Allows the owner or the manager to set a new manager.

function setManager(address manager_) external onlyManagerOrOwner;

For manager


Allows the manager to add a solver.

function addSolver(address solver) external onlyManager;


Allows the manager to remove a solver.

function removeSolver(address solver) external onlyManager;

For anyone


A view function that returns whether an address is a solver. This method is used by the settlement contract to ensure critical functions can only be invoked by accounts passing the allow-list authentication.

function isSolver(
address prospectiveSolver
) external view override returns (bool);


  • ManagerChanged - when the manager is changed
  • SolverAdded - when a solver is added
  • SolverRemoved - when a solver is removed