Constant WALK_EVAL_CEILING 

pub const WALK_EVAL_CEILING: usize = _; // 384usize

Hard ceiling on budgeted spine evals across one coupled walk — the #968 termination guarantee made structural. A clean walk budgets PATH_BUDGET + (CONTINUATION_WAYPOINTS − 1) · WARM_LEG_EVAL_BUDGET (one cold entry spine, then warm legs); the ceiling leaves ~3× that for homotopy-floor bounces. At the ceiling the path arrives with its best converged state instead of spending another leg: a walk cannot spin.