Challenge and clarify requirements before planning or implementing a software change — feature requests, bug reports, specifications, tickets, and proposed solutions. Finds missing outcomes, ambiguous behavior, conflicting constraints, hidden assumptions, unsafe defaults, and untestable acceptance criteria, asks the few questions that matter, and produces a requirements brief with explicit decisions and unresolved blockers. Use only when the user asks to challenge, clarify, or pressure-test requirements, not automatically for every request.