The Gap Between a Model and a ProductWhat “Production AI System” Means in 2026Three Reference ArchitecturesLTX Desktop: Eight PatternsPattern 1: The Two-Process ArchitecturePattern 2: Backend as Source of TruthPattern 3: The Typed IPC BridgePattern 4: Localhost as a Security BoundaryPattern 5: Model Lifecycle: Download, License, StoragePattern 6: State as Discriminated UnionsPattern 7: Service Protocols and Fakes (No Mocks)Pattern 8: Lock-Aware HandlersThe Landscape: Three Architectures, One ProblemComfyUI: Community Plug-in MeshInvokeAI: Service-Oriented MonolithCapstone: Building a Custom Extension Across Three PlatformsThe Feature: Add LTX-2 Audio-to-Video as a New CapabilityImplementation in LTX DesktopImplementation in ComfyUIImplementation in InvokeAIWhat the Three Implementations RevealSummary and Conclusion: The Video AI Landscape