/**
 * Adds token counts while preserving an unknown total when both counts are
 * unknown.
 */
export function sumTokenCounts(
  tokenCount1: number | undefined,
  tokenCount2: number | undefined,
): number | undefined {
  return tokenCount1 == null && tokenCount2 == null
    ? undefined
    : (tokenCount1 ?? 0) + (tokenCount2 ?? 0);
}