phase-roadmap-builder
Produces or extends a multi-phase roadmap spec (`specs/phase-plans-v<N>.md`) that `/plan-phase` can ingest. Use when the user wants to turn the current conversation's plan, an architecture discussion, or a pointed-at markdown spec into a phased roadmap — phrases like 'build a phase roadmap', 'turn this into a phased plan', 'create a multi-phase spec', 'add a phase to the roadmap', 'extend the phase plan', or after a long planning conversation when the user says 'ok let's formalize this'. Also triggers when the user wants to APPEND phases to an existing roadmap without editing prior phases. Designs for maximum parallelism: fewer phases, more parallel lanes per phase, tight early interface freezes.