Typed Service Contracts (Spec & Handler Pattern) This skill defines a Vertical Slice Architecture backed by Design by Contract (DbC) principles. It treats application logic as rigorously defined Units of Work where inputs are parsed (not just validated) and errors are treated as values (Result Pattern) rather than exceptions. When to use this skill - Building CLIs or Libraries: When you need strict boundaries between user input and system logic. - Complex Validation: When inputs require transformation (parsing) before being useful (e.g., ensuring a string is a valid file path). - High-Reliabi…