Day 3: The Architecture

Overview

Day 3 is the deepest practice day. It has 6 ACIs -- the most of any day -- and covers the decisions that shape every agent interaction: how CLAUDE.md evolves over time, which rules matter and which do not, how to prevent the duplication that agents create, and how to extend agent capabilities through skills.

The first three ACIs tell a lifecycle story: CLAUDE.md starts as a living document (002), you discover that style rules are noise and architecture rules are signal (008), and eventually you simplify (006). This is a trajectory that every project goes through. The remaining three address code-level architecture: duplication prevention (001), namespace design (011), and extensibility (016).