Function run 

pub fn run(
    paths: &DataPaths,
    live_commands: &[String],
    dry_run: bool,
    only: Option<&[String]>,
    max_idle: Duration,
    now: SystemTime,
) -> Run

Plan, and unless dry_run, carry out, a prune. dry_run is the caller’s explicit choice to delete: nothing in AgentMux calls this with false except a user action.

only: remove just these directories (the ones an earlier dry run listed), and only if they are still removable now. Anything that became removable since is left alone, so a removal is exactly what the user was shown.