SCU3.0 Architecture and Extension Plan: Three-Dimensional Separation of Data Flow, Dependency Direction, and Cross-Cutting Guard in a Four-Layer Cognitive Framework

This document presents the SCU3.0 architecture, which achieves three-dimensional separation of concerns by orthogonalizing data flow, dependency direction, and cross-cutting guard auditing into independent axes. The system is structured as a four-layer hierarchy—D (axiom/baseline), M (metacognition/LLM orchestration), W1 (action/tool execution), and W2 (perception/routing)—with strictly unidirectional dependencies flowing downward. Four axioms govern all cross-layer operations: A1 (baseline immutability), A2 (entropy tax economics), A3 (contract closure), and A4 (layer unidirectionality), enforced at five designated guard points. The architecture introduces an Entropy Tax Ledger with a five-factor taxation model and a Yin-Yang Pair Thinking system employing dual LLM platforms (DeepSeek-Chat as Yin critical perspective, Qwen-Plus as Yang supportive perspective) with a Tai-Chi synthesis step. Extension capabilities include a distributed executor with worker node registration and load balancing, a plugin marketplace with closed-loop lifecycle, a self-evolution engine, and a code self-modification engine protected by D-layer manifests and AST danger-pattern blacklists. Three-level memory (L1 working, L2 semantic, L3 episodic) combined with RAG knowledge retrieval provides context-aware information access.