Growth Log helps agents and users extract reusable patterns from complex tasks, failures, and retrospectives rather than writing superficial diary entries. It provides structured rules including focusing on failures, applying the Bole Principle to prevent duplicates, and ensuring every entry is transferable. The skill outlines a four-part entry template covering context, root cause, the transferable pattern, and related entries, along with a quality checklist and anti-patterns. Use it whenever you need to capture compound learnings across sessions in any note-taking system.