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Overview

calado batches in memory and flushes every 5 seconds on a timer. Serverless runtimes freeze between invocations, so that timer often never fires and events get stranded in a dead queue. The fix is to call calado.flush() before your handler returns. How you do that depends on the runtime.

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Next.js App Router

Use Next’s after() helper. It runs after the response is sent, so the user doesn’t wait on the flush. 
import { after } from "next/server";
import { calado } from "calado";

export async function POST(req: Request) {
  // ...handle the request, make LLM calls...

  after(() => calado.flush());

  return Response.json({ ok: true });
}

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Vercel Edge / Next.js Edge runtime

Use ctx.waitUntil so the platform keeps the worker alive until the flush resolves. 
import { calado } from "calado";

export default async function handler(
  req: Request,
  ctx: { waitUntil: (p: Promise<unknown>) => void }
) {
  // ...handle the request...

  ctx.waitUntil(calado.flush());

  return new Response("ok");
}

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AWS Lambda

Flush in a finally block so it runs on both success and error paths. 
import { calado } from "calado";

export async function handler(event: unknown) {
  try {
    // ...handle the request...
    return { statusCode: 200 };
  } finally {
    await calado.flush();
  }
}

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Cloudflare Workers

Same pattern as Vercel Edge. Workers provide ctx.waitUntil on the request handler’s second argument. 
export default {
  async fetch(req: Request, env: Env, ctx: ExecutionContext) {
    // ...handle the request...

    ctx.waitUntil(calado.flush());

    return new Response("ok");
  },
};

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Long-running Node processes

If your server stays warm between requests (Express, Fastify, a worker process), the default 5-second flush timer handles everything. You don’t need to call flush() manually. On graceful shutdown, call await calado.shutdown() to flush and clear timers. 
process.on("SIGTERM", async () => {
  await calado.shutdown();
  process.exit(0);
});

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Tuning batch size and flush interval

If you’re sending many events and want lower latency, lower the batch size or flush interval. 
calado.init(process.env.CALADO_API_KEY!, {
  batchSize: 5,
  flushInterval: 1_000,
});
Set flushInterval: 0 to disable the timer entirely. Use this in serverless setups where you always flush manually. See Node.js SDK → Init options for the full list.