Phase-by-phase deep inspection of any multi-phase plan — stop at each phase and assess completeness, quality, and future-readiness before advancing. Trigger when the user runs /deep-dive or asks to "do a deep dive", "inspect each phase", "look at this more carefully", or "check if we're missing anything" on an existing plan. Use plan-create to create a new plan, plan-execute to run an approved plan, and plan-phases to add gates to a plan.
