Function resolve_execution_account_address 

pub fn resolve_execution_account_address(
    private_key: Option<&str>,
    vault_address: Option<&str>,
    account_address: Option<&str>,
    environment: HyperliquidEnvironment,
) -> Result<Option<String>>

Resolves the execution account address used for REST queries and WebSocket subscriptions.

Precedence is explicit account address, explicit vault address, environment account address, environment vault address, then the signer address derived from the private key. Explicit and environment account addresses are trimmed, validated as 0x-prefixed lowercase or EIP-55 checksummed hex, and normalized to lowercase. A blank explicit account address is invalid; a blank environment account address is ignored.

Errors

Returns an error if a selected account address, vault address, or private key is invalid.