copilotkit-agui

SKILL.md

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 AbstractAgent.run() returning an RxJS Observable<BaseEvent>, 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 AbstractAgent.run() for a new framework integration

Debugging why events aren't reaching the frontend or arriving malformed

Understanding event ordering (lifecycle, text, tool calls, state)

Working with state synchronization (snapshots vs JSON Patch deltas)

Implementing human-in-the-loop interrupt/resume flows

Troubleshooting SSE streaming or encoding issues

When NOT to Use