Function parseColorFgBg

apps/kimi-code/src/tui/theme/detect.ts:111–121

(value: string | undefined)

 * the background ANSI 16-color index; 0–6 and 8 are dark, the rest light.
 */
export function parseColorFgBg(value: string | undefined): ResolvedTheme | null {
  if (value === undefined || value === "") return null;
  const parts = value.split(";");
  const bgRaw = parts.at(-1);
  if (bgRaw === undefined) return null;
  const bg = parseInt(bgRaw, 10);
  if (!Number.isInteger(bg)) return null;
  // ANSI 0=black, 1=red, 2=green, 3=yellow, 4=blue, 5=magenta, 6=cyan, 8=bright black.
  const darkBgs = new Set([0, 1, 2, 3, 4, 5, 6, 8]);
  return darkBgs.has(bg) ? "dark" : "light";
}