writtenRegex
A regular expression written as one: /…/, flags after it (/get|set/i); its source and flags.
export function writtenRegex(text: string): { source: string; flags: string } | undefined { const m = /^\/(.+)\/([dgimsuvy]*)$/s.exec(text); return m ? { source: m[1]!, flags: m[2]! } : undefined; }