With 10 trials and n_initial=5, PSO got 5 remaining evals for a
20-particle swarm. Only 5 of 20 particles were evaluated before the
budget observer killed the run — 75% of the swarm had no cost value.
PSO can't compute a proper gbest from partial data.
Fix: when remaining_trials < n_particles × 2, skip PSO entirely and
use additional LHS samples instead. LHS gives better space coverage
than an incomplete swarm iteration.
For 10 trials: 5 initial LHS + 5 additional LHS = 10 independent
space-filling samples. Much better than 5 LHS + 5 broken PSO particles.
PSO still runs when budget is sufficient (≥40 remaining for 20 particles).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
3e1f3fd0cc