What problem does it solve? Turning an approved architecture design into an actionable build plan is error-prone: phases overlap, files get double-owned, dependencies are vague, and failure states are forgotten until review. This Skill enforces a strict plan format and phase rules so every design element lands in exactly one verifiable phase. ## Core Features & Use Cases - Structured plan format: Generates void/plan/<slug>.md with a failure/edge-state table, phase DAG (depends:/shared:), and verification section inheriting the design's acceptance criteria. - Phase governance rules: Enforces one-concern-per-phase, file disjointness for parallel builds, checkable done when: criteria, and a proven-reuse rule that blocks premature abstraction. - Use Case: After an architecture design is approved, invoke this Skill to produce a phase plan where a builder can execute P1–P4 in order, knowing exactly which files each phase owns and what each phase consumes from prior phases. ## Quick Start Use the planning skill to turn the approved design at void/<task-slug>/architecture-design.md into a phase plan at void/plan/<slug>.md.