AbsoluteJS

@absolutejs/agent-exchange-a2a

@absolutejs/agent-exchange-a2av0.3.0betaAI

Negotiated, authenticated A2A client and server adapters for model-blind AbsoluteJS Agent Exchange.

#Installation

BASH
bun add @absolutejs/agent-exchange-a2a

#Capabilities

Overview

Interoperable A2A client and server adapters for Agent Exchange. The adapter discovers an A2A 1.0 Agent Card, requires the Agent Exchange extension to be advertised, activates it through A2A-Extensions, and places only the core package's opaque safe reference in task history. Dedicated cards can require the extension; shared cards can advertise it as optional.

The server authenticates the caller through the host-supplied A2A authorization function, then passes that verified caller and opaque reference to a deterministic executor. The executor must resolve the full request from trusted server state, verify the OAuth delegation and any signed standing mandate, and authorize it before source access. Results are projected into a bounded redacted receipt.

Prepared exchanges

A recipient that needs the complete request before the opaque A2A signal can advertise a same-origin preparation endpoint in the extension parameters:

connectAgentExchangeA2a() discovers that endpoint. Each send(request) posts the complete request there and verifies that the response contains the exact derived opaque reference before sending anything on A2A. Preparation and A2A credentials remain separate:

The preparation endpoint uses application/vnd.absolutejs.agent-exchange-preparation+json, accepts { request }, and returns { reference }. It must authenticate the delegated caller, validate and durably protect the request, reject replay, and return Cache-Control: no-store. The adapter rejects cross-origin preparation URLs, redirects, response media-type substitution, extra response fields, and any reference that differs from the request.

Show 3 more

Hosts with an existing trusted preparation channel can instead supply a prepare(request, context) callback. Omitting both an advertised endpoint and a callback retains out-of-band preparation mode.

The adapter intentionally does not transmit signed mandates, OAuth tokens, mailbox credentials, encrypted envelopes, account references, or verification codes through A2A. See the extension specification.

This is an experimental 0.x package and has not been independently audited.

Outcomes

What you can build

Build on the supported package contract

Use @absolutejs/agent-exchange-a2a through its supported public entry points.

Hardening checklist

Production guidance

Make every external boundary explicitPin the deployed @absolutejs/agent-exchange-a2a version, replace example or memory-backed dependencies with durable implementations, bound external calls, protect credentials, and emit enough evidence to retry or recover safely.

Follow in order

Troubleshooting path

1
Trace from the first failed boundary
Reproduce the smallest canonical @absolutejs/agent-exchange-a2a example, confirm the supported entry point and version in the API explorer, then inspect the first boundary that did not produce its documented result.

#@absolutejs/agent-exchange-a2a quick start

Partial snippet

# @absolutejs/agent-exchange-a2a

TS
import {
  connectAgentExchangeA2a,
  createAgentExchangeA2aHandler,
} from "@absolutejs/agent-exchange-a2a";

#Prepared exchanges

Partial snippet

A recipient that needs the complete request before the opaque A2A signal can advertise a same-origin preparation endpoint in the extension parameters:

TS
const handler = createAgentExchangeA2aHandler({
  agentCard,
  authorize,
  execute,
  preparationEndpoint: "https://recipient.example/agent-exchange/requests",
  taskStore,
});

#Prepared exchanges 2

Partial snippet

A recipient that needs the complete request before the opaque A2A signal can advertise a same-origin preparation endpoint in the extension parameters:

TS
const client = await connectAgentExchangeA2a({
  headers: () => a2aAuthorizationHeaders(),
  origin: "https://recipient.example",
  preparationHeaders: () => preparationAuthorizationHeaders(),
});

const receipt = await client.send(request);

#Public entry points

Supported entry points declared by this package manifest.

@absolutejs/agent-exchange-a2aPackage entry point declared in package.json.

#Package commands

Scripts declared by this package manifest.

bun run buildrm -rf dist && bun build src/index.ts --outdir dist --target=node --external @absolutejs/a2a --external @absolutejs/agent-exchange && tsc --project tsconfig.build.json
bun run check:packagebun run format:check && bun run typecheck && bun run test && bun run build
bun run format:checkprettier --check "./**/*.{ts,json,md}"
bun run testbun test tests/
bun run typechecktsc --noEmit

#API reference

Search the declarations exported by the current package type files. Expand a symbol to inspect its source-backed signature.

15 symbols
AGENT_EXCHANGE_RECEIPT_MEDIA_TYPEvaluePermalinkSource
TS
const AGENT_EXCHANGE_RECEIPT_MEDIA_TYPE: "application/vnd.absolutejs.agent-exchange-receipt+json";
Exported from @absolutejs/agent-exchange-a2a