Adding monitoring to a Cursor app

Cursor is an IDE with AI built in. It works with any stack, so what comes out depends on your project. This is how to add error tracking and uptime monitoring with Upflag.

Where Cursor apps break

You're editing code through conversation and tab completions. Cursor modifies files across your project, sometimes several at once. The code compiles, the dev server runs, but there are failure modes that don't show up until production.

Multi-file edits are the main source of trouble. A refactor that fixes one module can silently break an import somewhere else. You accept the changes, everything looks right in the editor, but a route is now returning 500s or a component stopped rendering.

Merge conflicts with AI-generated code are another one. You pull from main, Cursor helps resolve the conflicts, and the result has subtle bugs that pass a quick visual check. A function signature changed, a variable got renamed in one place but not another, an edge case got dropped.

Random JavaScript errors pile up too. A component throws, React catches it, and the user gets a blank white page or a spinner that never resolves. You're not going to catch that in your editor.

And then integrations. You ask Cursor to restructure an API layer and it doesn't know your Stripe webhooks depend on that exact path. The app runs fine. Your payments are broken.

Setup

1. Get your project key

2. Add two script tags

Add these two tags to your <head> — both are needed. The first buffers any errors that fire before the main snippet loads:

<script>window.__ufq=[];window.addEventListener("error",function(e){window.__ufq.push(e)});window.addEventListener("unhandledrejection",function(e){window.__ufq.push(e)})</script>
<script src="https://upflag.io/api/v1/snippet?key=uf_YOUR_KEY" defer></script>

Replace uf_YOUR_KEY with your key from the Upflag dashboard.

Where to put them depends on your framework:

Next.js: app/layout.tsx
Vite/React: index.html
Astro: your layout component's <head>
Plain HTML: index.html

Or just run npx upflag init and it'll detect your framework and add them for you.

It starts capturing JavaScript errors and page loads right away.

3. Set up alerts

In the Upflag dashboard, pick where you want notifications: email, Slack, or SMS. Alerts say what broke in plain English ("Your signup form started throwing errors") instead of a stack trace.

After setup

Upflag checks your URL every 60 seconds. Hosting goes down, DNS breaks, SSL expires, you'll know.

For Cursor projects specifically, the biggest value is catching breakage after multi-file refactors. You accept a batch of changes, push to production, and error tracking tells you if something you didn't notice went wrong. Failed fetches, uncaught exceptions, components that stopped rendering.

Keep an eye on whatever flows make your app work. If signups or payments break after a Cursor session where you changed a lot, you want to know that day, not next week.

Using the MCP server

You can connect Upflag as an MCP server in Cursor so it can see your production errors while you're coding. Add it in Cursor's MCP settings with your Upflag API key.

Once connected, you can ask Cursor to check for recent errors and fix them directly. Instead of you copying an error message from a dashboard and pasting it into the chat, Cursor already knows what's broken. It sees which page threw, what the error was, and can go straight to fixing it.

This doesn't replace the script tags. The tags capture errors in the browser. The MCP connection is what lets Cursor read those errors back.

Monitoring for Cursor Apps