/** Format the five headline Alpha metrics for display; stored/filter values stay raw.
 * Unsupported fields return undefined so callers can retain their existing format.
 */
export function formatAlphaMetric(
  key: string,
  value: unknown,
): string | undefined {
  const percent = key === "turnover" || key === "returns" || key === "drawdown";
  if (!percent && key !== "sharpe" && key !== "fitness") return undefined;
  if (typeof value !== "number" || !Number.isFinite(value)) return "—";
  return percent ? `${(value * 100).toFixed(2)}%` : value.toFixed(2);
}