# Executing Offers

### Overview

Offers listed on Mangrove are tied to an associated account, either an Externally Owned Account (EOA) or a Maker Contract.

* If the account is an EOA, the offer has no custom logic. These are called on-the-fly offers. The EOA must already hold the promised liquidity when its offer is matched.
* If the account is a maker contract, it must implement the [IMaker interface](https://github.com/mangrovedao/mangrove-core/blob/2ae172805fd8b309c30b2dc877dba66245abbb3e/src/core/MgvLib.sol#L420-L430).\
  At minimum, it must define the makerExecute function, otherwise all offer executions will fail.

### Offer Lifecycle

1. A maker contract (`maker.eth`) creates an offer.
2. Mangrove stores the offer data, including the maker’s address `maker.eth`.
3. A taker (`user.eth`) submits a market order that matches the offer.
4. Mangrove transfers tokens from `user.eth` → `maker.eth`.
5. Mangrove calls `makerExecute` on `maker.eth`.
6. Mangrove transfers tokens from `maker.eth` → `user.eth`.
7. The offer is removed from the offer list.
8. If execution fails, Mangrove rolls back to the pre-trade state (step 4) and compensates the taker with a bounty, paid from the offer’s provision.
9. Mangrove calls `makerPosthook` on `maker.eth` (if implemented), allowing the maker to update or repost offers.

### Multiple Offers per Maker

A single maker contract or EOA can manage multiple offers. When Mangrove calls `makerExecute`, it includes the offer [id](/dev/quick-links/glossary.md#offer-id) and related execution data, allowing the maker contract to identify which specific offer was triggered.

### **Example Scenario**

A maker contract has an offer promising 100,000 DAI in exchange for 100,000 USDC.

Execution proceeds as follows:

1. Mangrove calls `makerExecute`, having just transferred 100,000 USDC from the taker to the maker contract.
2. The maker contract sources 100,000 DAI, possibly from another protocol, pool, or on-chain strategy.
3. By the end of execution, the maker must ensure that 100,000 DAI are available for Mangrove to transfer to the taker via `transferFrom`.

If this final transfer fails, Mangrove cancels the trade and compensates the taker using the offer’s provision.


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