Plan Split

What this skill does

1. Read Plans.md and extract all ## Phase N: sections
2. For each phase, check if docs/plans/phase-N.md already exists
3. For phases without a file, generate a phase-N.md following the harness format:
   • Created date
   • Origin (起点)
   • Purpose (目的)
   • Dependencies (依存)
   • Sub-phases with task tables (cc:TODO markers)
   • Acceptance criteria checklist
4. Append a link to Plans.md for the new phase: [phase-N.md](docs/plans/phase-N.md)
5. Report: "Phase N のファイルを生成しました: docs/plans/phase-N.md"

Format for generated phase-N.md

# Phase N: <title>

作成日: <today>
起点: <inferred from task descriptions>
目的: <inferred from task descriptions>

依存: <from priority matrix>

---

## Phase N.0: <first sub-phase>

| Task | 内容 | Status |
|------|------|--------|
| N.0.1 | <extracted from Plans.md> | cc:TODO |

---

## 受け入れ条件

- [ ] <key acceptance criteria>