The agentic AI stack has a missing layer. MCP solved context. A2A solved agent-to-agent communication. But the agent-to-user layer — the frontend — had no standard until AG-UI launched in 2025. Developers are now asking: "I have an agent. How do I give it a face?" This talk answers that question with working code, not theory. Three open protocols now solve this. AG-UI streams agent state to your UI in real time. A2UI lets agents describe the interface they need as data your app renders automatically. MCP Apps return interactive HTML in sandboxed iframes. You'll see all three in a live Next.js app with CopilotKit and Vercel AI SDK — four demos with take-home code you can drop into your project the same day. React hooks are all you need.