Function span

scripts/agent-eval/compare-arms.mjs:95–102

median [min–max] over runs; the range is the point — never quote one run.

(runs, pick, fmt = (x) => String(Math.round(x)))

/** median [min–max] over runs; the range is the point — never quote one run. */
function span(runs, pick, fmt = (x) => String(Math.round(x))) {
  const xs = runs.map(pick).filter((x) => x !== null && x !== undefined && Number.isFinite(x));
  if (!xs.length) return '—';
  const m = fmt(median(xs));
  if (xs.length === 1) return m;
  const lo = fmt(Math.min(...xs)); const hi = fmt(Math.max(...xs));
  return lo === hi ? m : `${m} [${lo}–${hi}]`;
}

const int = (x) => Math.round(x).toLocaleString('en-US');
const pct1 = (x) => `${x.toFixed(1)}%`;