code-designing

Reference: See reference.md for complete design principles and examples.

<quick_start>

1. Analyze Architecture: Check for vertical vs horizontal slicing
2. Understand Domain: Identify problem domain, concepts, invariants
3. Identify Core Types: Find primitives that need type wrappers
4. Design Self-Validating Types: Create types with validating constructors
5. Plan Package Structure: Vertical slices by feature
6. Output Design Plan: Present structured plan before implementation

Ready to implement? Use @testing skill for test structure. </quick_start>