AG-UI Protocol Skill Overview AG-UI (Agent-User Interaction) is CopilotKit's open event-based protocol for agent-to-UI communication. All agent-frontend interaction flows through typed events streamed over SSE (Server-Sent Events) or binary protobuf transport. Agents implement returning an RxJS , and the client SDK handles event application, state management, and message history. When to Use - Building a custom agent backend that needs to speak AG-UI - Implementing for a new framework integration - Debugging why events aren't reaching the frontend or arriving malformed - Understanding event o…