@ag-ui/core

@ag-ui/core

TypeScript definitions & runtime schemas for the Agent-User Interaction (AG-UI) Protocol.

@ag-ui/core delivers the strongly-typed building blocks that every other AG-UI package is built on: message & state models, run inputs and the full set of streaming event types.

Installation

# types and constants only — no runtime dependencies
npm install @ag-ui/core
pnpm add @ag-ui/core
yarn add @ag-ui/core

# to use the validators on @ag-ui/core/schemas, add zod (3.25.18+ or 4.x)
npm install @ag-ui/core zod

zod is an optional peer dependency: the main entry never loads it, so an application that only needs the types installs nothing else.

Features

• Typed data models – Message, Tool, Context, RunAgentInput, State …
• Streaming events – over 30 event kinds covering assistant messages, tool calls, state updates, reasoning, activity, and the run and subagent lifecycles.
• Runtime validation – schemas catch malformed payloads early.
• Framework-agnostic – works in Node.js, browsers and any agent framework that can emit JSON.

Quick example

import { EventType } from "@ag-ui/core";
// Validators live on the /schemas subpath and need zod installed; the main
// entry is types and constants only, so type-only consumers need no zod.
import { EventSchemas } from "@ag-ui/core/schemas";

// Validate an incoming event
EventSchemas.parse({
  type: EventType.TEXT_MESSAGE_CONTENT,
  messageId: "msg_123",
  delta: "Hello, world!",
});

Documentation

• Concepts & architecture: docs/concepts
• Full API reference: docs/sdk/js/core

Contributing

Bug reports and pull requests are welcome! Please read our contributing guide first.

License

MIT 2025 AG-UI Protocol Contributors