Read-only codebase and requirement exploration before planning. Use when the user asks how code works, wants relevant files and validation commands identified, has an unclear or open-ended development request, needs implementation approaches compared before dev-write-plan, or wants a plan or design grilled/stress-tested. Clarifies by grilling by default — one question at a time with a recommended answer until the design holds up; say "don't grill me" for minimal questioning. Never edits files; reports findings, clarified requirements, and an approved design direction in chat.
