Use immediately when user mentions: "処理フロー", "processing flow", "フロー図", "flow diagram", "Mermaid", "アーキテクチャ", "architecture", "理解負債", "understanding debt", "なぜ", "why", "数式", "理論", "可視化", "visualization", "詳細", "drill-down", "method-level".
MUST USE this skill for:
- Creating hierarchical processing flow documentation with C4 model
- Multi-level drill-down from system → container → component → code
- Documenting mathematical foundations and algorithms
- Recording decision rationale (ADR format)
- Reducing understanding debt for AI-generated code
- Visual context tracking with Mermaid diagram highlighting