Function start_settle 

pub fn start_settle(
    parent: &Arc<ScopeKernel>,
    phase_kernel: &Arc<ScopeKernel>,
    objective: &str,
    reporter: &Arc<CadenceReporter>,
    stop_flag: Arc<AtomicBool>,
) -> Result<SettleHandle, SettleSkip>

Start a cadence-fed settle detector for objective on the running phase iff the objective reads live metrics. Builds the objective kernel as node X’s program rebound to parent (carrying the coordinate — mirrors read_objective_at_completion), wraps it in a PhaseStopEvaluator, and subscribes it to the smallest cadence. Starts nothing for a non-volatile objective (the one-shot read path is correct there) or when the metrics cadence is disabled, and says which; a detector that cannot be built is SettleSkip::Failed.