Think ~ Etherscan + Remix.

Basically, it's a way to interact with contracts and EOAs in a simulated environment, from a forked chain, with a comprehensive set of actions exposed by Tevm memory clients.

As you interact with accounts, all transactions are processed and recorded by the client, which always considers the latest state of the chain; i.e. the initial state at the time of the fork, plus all the local transactions.

When you search for a contract, it will attempt to retrieve its ABI with WhatsABI. You can then interact with it using the interface, or perform any arbitrary call with encoded data.

The clients for each chain are synced with the local storage, as well as the transaction history. When the chain is reset, the client forks the chain again at the latest block, which incidentally resets the local transactions history.