/**
 * Pass 2 public thinking is a complete product sentence, never a CoT fragment.
 * This gate only accepts or rejects. It must not rewrite, strip, or splice.
 */
const CJK_RE = /[\u4e00-\u9fff]/;
const SENTENCE_RE = /[。！？]/;

export const THINK_STEP_TEXT_MIN = 8;
export const THINK_STEP_TEXT_MAX = 400;

export function acceptThinkStepText(text: string): string | null {
  const trimmed = text.replace(/\s+/g, " ").trim();
  if (trimmed.length < THINK_STEP_TEXT_MIN || trimmed.length > THINK_STEP_TEXT_MAX) return null;
  if (!CJK_RE.test(trimmed)) return null;
  if (!SENTENCE_RE.test(trimmed)) return null;
  return trimmed;
}