================
 Overview
================

Actions on Mero require externally owned accounts to trigger or execute them. For instance, a collateral top up can only occur if it is called externally. Mero incentivizes keepers to execute actions by paying them a share of the fees.


Collateral Top Ups
==================

The first supported action on Mero is collateral top ups.

Keepers of this action can execute collateral top ups for accounts that have registered a top up position on Mero. All interaction regarding collateral top ups occur through the `TopUpAction contract <https://github.com/merofinance/protocol/blob/main/contracts/actions/topup/TopUpAction.sol>`_.

To execute a topup anyone can all the execute function below.

.. py:function:: TopUpAction.function execute(address payer, address account, address beneficiary, bytes32 protocol) external override returns (bool)

    Top up a registered position on an external protocol (e.g. AAVE or Compound) if the position's conditions are met. Pool and vault funds are rebalanced after withdrawal for top up

    * ``payer``: Account that pays for the top up.
    * ``account``: Account owning the position for top up.
    * ``beneficiary``: Address of the keeper's wallet for fee accrual.
    * ``protocol``: Protocol of the top up position. *Note*: this is the name of the protocol represented as ``bytes32``.

There is also an execute function that accepts an additional value ``maxWeiForGas``:

.. py:function:: TopUpAction.function execute(address payer, address account, address beneficiary, bytes32 protocol) external override returns (bool)

    Top up a registered position on an external protocol (e.g. AAVE or Compound) if the position's conditions are met. Pool and vault funds are rebalanced after withdrawal for top up

    * ``payer``: Account that pays for the top up.
    * ``account``: Account owning the position for top up.
    * ``beneficiary``: Address of the keeper's wallet for fee accrual.
    * ``protocol``: Protocol of the top up position. *Note*: this is the name of the protocol represented as ``bytes32``.
    * ``maxWeiForGas``: The maximum extra amount of wei that the keeper is willing to pay for the gas.

For a keeper to execute an action, they have to first meet the requirement for the minimum amount of MERO staked. This is a measure in place to protect keepers against general purpose frontrunning bots.

To see how much MERO is required to execute a top up, you can call the ``Controller.getKeeperRequiredStakedMERO()`` view. And to see if an address meets that requirement, you can call the ``canKeeperExecuteAction(address keeper)`` view.

To assist with building keeper bots, a helper contract has been deployed ``KeeperHelper``. More details on this in the dedicated section below.