@relaymessenger/vercel-ai

Relay plugin for the Vercel AI SDK: receive signed message.received webhooks and stream a model reply back to Relay as one canonical message. Relay owns the messenger; your backend owns the model, tools, and hosting. Raw HTTPS remains the canonical contract — this package is a thin, dependency-free binding of it.

import { createRelay } from "@relaymessenger/vercel-ai";
import { streamText } from "ai";

const relay = createRelay({
  token: process.env.RELAY_AGENT_TOKEN!,
  webhookSecret: process.env.RELAY_WEBHOOK_SECRET!,
});

// Next.js: app/api/relay/route.ts
export const POST = relay.webhook(async ({ message, typing, reply }) => {
  await typing();
  const result = streamText({
    model: "anthropic/claude-sonnet-5",
    prompt: message.parts.find((p) => p.type === "text")?.text ?? "",
  });
  await reply.stream(result.toUIMessageStreamResponse());
});

What the plugin enforces for you, per the public contract (https://docs.relayapp.im):

• Standard Webhooks signature verification over the exact raw body.
• event_id deduplication per instance, recorded only after your handler succeeds; unknown event types acknowledge without dispatch.
• Deterministic Idempotency-Key derivation (event_id:n): even when a redelivery reaches another instance, Relay replays the original send instead of double-posting.
• Group invocation_id threading into every reply and typing call.
• One-shot UI message stream commits: POST /v1/messages?stream=true with x-vercel-ai-ui-message-stream: v1; Relay commits exactly one message.

See the guide: https://docs.relayapp.im/guides/vercel-ai-sdk.