Holon is a cognitive architecture overlay for large language models that provides persistent, structured memory across conversational sessions. Unlike RAG-based approaches requiring external infrastructure, Holon implements in-process holographic memory inspired by Holographic Reduced Representations (HRR), Free Energy Principle, and Rao–Ballard predictive coding.The system runs entirely on mobile hardware (ARM64/Android, ~30MB RAM) without GPU acceleration. Core components include: a three-level Φ matrix evolving over time with session-persistent holographic encoding; PrismRouter — a novel physics-inspired continuous routing mechanism replacing hard-threshold level selection; ConversationTracker for short-term continuity and automatic topic extraction; and emotionally-weighted adaptive learning rate via AIIState.Benchmark results: 100% recall at 80 noise turns, 93–100% precision. Live-validated over 150+ conversational turns on a smartphone.Part of the HolonOS ecosystem — an agent-first mobile operating system architecture where the LLM interface replaces the application launcher.Keywords: holographic memory, persistent memory, conversational AI, predictive coding, free energy principle, mobile AI, on-device inference, cognitive architecture