Converge with Solanalab's SIWS #25
Description
The account is an optional Wallet Standard WalletAccount in the request, and required in the signed message and method output. This means an application can sign in and connect to the wallet in a single step. It doesn't need to asynchronously connect to get an account, prepare a message to sign in, then prompt the user to sign it. It can sign in without knowing what account to sign in with, and when the message is signed, the account will be connected as well.
The chain is a Wallet Standard chain IdentifierString. This would typically be solana:mainnet, but others are defined here, and this is arbitrary.