Vercel Functions error tracking your coding agent can read

A Vercel Function can be frozen as soon as it responds, and the Runheed Node SDK batches events for up to 5 seconds, so the send has to be part of the request. waitUntil from @vercel/functions keeps the function alive until the error is sent without making the user wait for it. Vercel also sets VERCEL_ENV and VERCEL_GIT_COMMIT_SHA, so every error carries the deploy that caused it, and your agent can resolve it with the commit that fixed it.

Set it up

1.Install the SDK and Vercel's helper, and add RUNHEED_DSN under Project Settings > Environment Variables (or with the CLI).
terminalbash
```
npm install https://runheed.com/dl/runheed-0.1.0.tgz @vercel/functions
vercel env add RUNHEED_DSN production
```

2.Report the error, return the response, and let waitUntil finish the send.

api/checkout.tstypescript

import runheed from 'runheed';
import { waitUntil } from '@vercel/functions';

runheed.init({
  dsn: process.env.RUNHEED_DSN!,
  environment: process.env.VERCEL_ENV ?? 'development',
  release: process.env.VERCEL_GIT_COMMIT_SHA,
});

export default {
  async fetch(request: Request): Promise<Response> {
    try {
      const { cartId } = await request.json();
      // ...your code
      return Response.json({ ok: true, cartId });
    } catch (err) {
      runheed.captureException(err as Error, { method: request.method, url: request.url, region: process.env.VERCEL_REGION });
      waitUntil(runheed.flush());
      return Response.json({ error: 'Internal error' }, { status: 500 });
    }
  },
};

3.Next.js 15.1 or later on Vercel: in a route handler, after() from next/server does the same job (Vercel recommends it over waitUntil in Next.js). For errors that escape your code, use the onRequestError setup on the Next.js page.

app/api/checkout/route.tstypescript

import { after } from 'next/server';
import runheed from 'runheed';

export async function POST(request: Request) {
  try {
    // ...your code
    return Response.json({ ok: true });
  } catch (err) {
    runheed.captureException(err as Error, { route: '/api/checkout' });
    after(() => runheed.flush());
    return Response.json({ error: 'Internal error' }, { status: 500 });
  }
}

4.Connect your agent with the server URL and a sign-in (Claude Code shown; Cursor, claude.ai and ChatGPT take the same URL).
terminalbash
```
claude mcp add --transport http runheed https://runheed.com/api/mcp
```

The npm and PyPI releases are not out yet, so these commands install the same package files straight from runheed.com. Nothing else changes when the registry versions ship.

What it catches

Errors in Vercel Functions on the Node.js runtime, with method, URL, region, environment and the deploy's commit
Errors you report yourself with captureException and any context you pass
Preview and production deploys kept apart by environment (VERCEL_ENV)

What it does not do

A function that hits its maxDuration is stopped, and pending waitUntil work is cancelled with it
Edge runtime functions need the fetch-based setup from the Cloudflare Workers page instead of the Node SDK
Browser errors are not captured; there is no browser SDK yet

Then ask your agent

> what broke in production since the last deploy? fix the top one and resolve it with the commit hash

Common Vercel Functions errors

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