Function run 

pub async fn run(
    agent: Arc<dyn AgentCore>,
    cwd: PathBuf,
    resume: Option<SessionId>,
) -> Result<()>

Run an interactive REPL until stdin EOF (Ctrl-D) or until :q / :quit / :exit is read.

cwd is the session working directory (the root of the local filesystem / shell backend). When resume = Some(id), the session is resumed (replaying history to the terminal) instead of creating a new one.