A comprehensive .NET library for replacing primitive obsession with strongly-typed, self-validating domain models across four pillars: semantic strings with 50+ validation attributes, polymorphic path handling, metadata-generated semantic quantities, and musical value types. The quantity system covers 60+ physical dimensions and 200+ generated types under a unified vector model, with compile-time dimensional safety, generated unit conversions and physics relationships, centralized physical constants, and optional per-storage-type alias packages. The music types provide type-safe pitches, intervals, scales and modes, chords with symbol parsing and voicing, keys with roman-numeral analysis, and rational durations and time signatures. Features factory-pattern and dependency-injection support for building robust, maintainable scientific and domain-specific applications.