Function launch_command 

pub fn launch_command(
    path: &Path,
    scope: &PathScope,
    action: RevealAction,
) -> Result<OwnedCommand>

Checks path against scope (and, for RevealAction::Open, against runnable files), then returns the command, not yet started. Stdio is null and the environment is DEFAULT_ENV_ALLOWLIST plus the desktop-session variables a launcher needs.