Function handle 

pub fn handle(
    cache: &mut SessionCache,
    task: &str,
    path: Option<&str>,
    _crp_mode: CrpMode,
) -> (String, bool)

Returns the rendered preload plus whether it actually carries context (#1134). Callers must not re-derive that from the body: the guidance strings below are prose and drift, and a preloaded file may quote them.