Provider–Observer–Operator: A Role-Based Abstraction Discipline for Interface-Led Architecture

This technical note defines Provider–Observer–Operator as a role-based abstraction discipline for applying Interface-Led Architecture (ILA) to concrete software design and refactoring. The paper classifies interface-bearing components into Provider, Observer, and Operator roles. It defines Units as governed compositions of roles and connects Units through Pipelines operating under Core Contracts. It also clarifies that exceptions are not roles, but failure states or transition results that occur when a Pipeline can no longer proceed under its Core Contract. The paper supplements the existing Interface-Led Architecture methodology by defining how interfaces are extracted from software systems. Semantic IR, Composite Distance, Governed Circuits, and ReplayLog are treated not as general ILA concepts, but as AIKernel-specific specializations. The Reactive Manifesto is cited as a comparative reference for observer-centered and message-driven system design, not as a dependency, replacement target, or criticism of reactive systems. The English manuscript is the canonical version. The Japanese manuscript is included as a companion translation.