const markdownSyntax = /[*_#`~|<>[\]\\!&=+\r-]|:\/\/|www\.|@|\t|^[ ]|[ ]$|^\d+[.)]/m;

export function plainParagraphs(text: string): readonly string[] | null {
  if (markdownSyntax.test(text)) return null;
  return text.split(/\n{2,}/).map((block) => block.trim()).filter(Boolean);
}