Function worst_constraints 

pub fn worst_constraints<S: AsRef<[f64]>>(replicates: &[S]) -> Vec<f64>

The conservative aggregate of several evaluations’ constraint vectors: the componentwise worst (maximum) value.

This is how a multi-seed fan’s k replicate vectors become the one vector the trial carries. Maximum, and not the mean or the last one, because the sign convention makes the largest value the worst one, and because “this configuration is feasible” must mean feasible under every seed: a configuration that satisfies a constraint on two replicates and violates it on the third has not satisfied it. Averaging would let two comfortable replicates pay for one violation, and keeping the last would make feasibility a function of replicate order.

If every replicate recorded nothing (including when there are no replicates), the result is empty: the fan is unconstrained. Once one replicate declares a width N, every replicate must declare exactly N values, including the replicates that recorded nothing. A missing or ragged row therefore returns an all-NaN marker with the maximum declared width. That marker is deliberately unmistakably invalid: it is not feasible and has infinite total violation, so it cannot rank as feasible. Its shape is stable under replicate permutation. For equal-width rows, a NaN wins over any finite value in its component, so an unevaluated constraint cannot be averaged away either — though TrialCtx::record_constraints refuses a non-finite value at the source, so it should never get this far.

use atune_core::pareto::worst_constraints;

// Satisfied on two seeds, violated on the third: the trial is infeasible.
let fan = [vec![-1.0, -2.0], vec![-3.0, 0.5], vec![2.0, -1.0]];
assert_eq!(worst_constraints(&fan), vec![2.0, 0.5]);

// Feasible on every replicate stays feasible.
let clean = [vec![-1.0], vec![-0.5]];
assert_eq!(worst_constraints(&clean), vec![-0.5]);

// Nothing recorded is not a declaration.
let silent: [Vec<f64>; 2] = [Vec::new(), Vec::new()];
assert!(worst_constraints(&silent).is_empty());