Walks your product every weekday in its own test account and tells you what shipped, what got unshipped, what broke (with repro steps and screenshots).
Yunjian's verifier: give it a prompt, Skill, web page or mini-program; it says whether it's ready to ship and what to fix, with evidence. Checks, never edits.
Your bots forget what you told them weeks ago. Librarian interviews your Grok Bots every week, finds the standing instructions you gave them, and flags the ones that are slipping.