@ag-ui/a2a

A TypeScript integration that connects AG-UI agents with remote services that expose the A2A protocol. It converts AG-UI conversations into A2A payloads, forwards them through the official A2A SDK, and replays the responses back into AG-UI event streams.

Status: Experimental. APIs may change while the integration stabilises.

Features

• Message conversion helpers between AG-UI and A2A formats (user, assistant, tool, binary payloads).
• A2AAgent implementation that streams or performs blocking requests against A2A endpoints.
• Optional fallback from streaming to blocking requests when an agent does not support SSE.
• Event conversion utilities that surface A2A messages, task status updates, and artifact chunks as AG-UI events.
• Helper tool schema (send_message_to_a2a_agent) for orchestration scenarios.
• Example client and Vitest tests to validate conversions and streaming flows.

Installation

Once dependencies are installed in the monorepo:

pnpm install
pnpm --filter @ag-ui/a2a build

Quick start

import { A2AAgent } from "@ag-ui/a2a";

import { A2AClient } from "@a2a-js/sdk/client";

const client = new A2AClient("https://my-a2a-agent");

const agent = new A2AAgent({
  a2aClient: client,
  initialMessages: [{ id: "user-1", role: "user", content: "Plan a team offsite" } as any],
});

const { result, newMessages } = await agent.runAgent();
console.log(result);
console.log(newMessages);

You can inject your own A2AClient instance via the client option, override default instructions, or force blocking mode by setting strategy: "blocking".

Configuration reference

Environment variables & authentication

The integration relies on the underlying A2A agent for authentication. Common patterns include:

• A2A_AGENT_URL – set in deployment environments to point to the remote agent base URL.
• A2A_API_KEY or A2A_BEARER_TOKEN – consumed by a wrapped fetch inside a custom A2AClient instance if the remote agent enforces API key or bearer authentication.

Pass any credentials to the A2AClient you provide to A2AAgent, or configure an HTTP proxy that injects the correct headers.

Utilities

• convertAGUIMessagesToA2A(messages, options) — reshapes AG-UI history into A2A message objects, forwarding only user/assistant/tool turns and preserving the tool payloads.
• convertA2AEventToAGUIEvents(event, options) — maps an A2A stream event to AG-UI text and tool events (TEXT_MESSAGE_CHUNK, TOOL_CALL_*, TOOL_CALL_RESULT).
• sendMessageToA2AAgentTool — JSON schema describing a send_message_to_a2a_agent tool for orchestration agents.

Testing

pnpm --filter @ag-ui/a2a test

The suite covers conversion edge cases and streaming / fallback behaviour using mocked A2A clients.

Examples

• examples/basic.ts – minimal script. If you set A2A_AGENT_URL, it will connect to that agent through the real A2AClient. Otherwise it falls back to a tiny in-memory mock client so you can observe the integration without hitting a remote endpoint.

Release checklist

1. pnpm --filter @ag-ui/a2a build
2. pnpm --filter @ag-ui/a2a test
3. Update CHANGELOG / release notes.
4. Publish with pnpm publish --filter @ag-ui/a2a.