Grades the evidence behind any claim, draft, document, code or data, tests counterarguments and says what holds and what to fix. Solo or as a team reviewer.
Pre-launch gate for an app, site, or paid plan that tests the happy and failure paths, data access rules, and leaked keys, then rules GO or NO-GO on evidence.
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.