The .cursorrules file I wish I had when building my SaaS

I've been using Cursor to build a Node.js + TypeScript SaaS,
and it's genuinely impressive — until it isn't.

The frustrations were always the same:

• Silent catch blocks with no logging
• any types slipping through everywhere
• Inconsistent API responses (sometimes data, sometimes result)
• Prisma queries without proper error handling
• Hardcoded secrets instead of environment variables

I kept correcting the same mistakes over and over.
So I did what any developer would do — I wrote rules.

What is .cursorrules?

A .cursorrules file sits in your project root and tells
Cursor how to behave in YOUR codebase. Think of it as a
style guide that the AI actually reads and follows.

The difference is dramatic.

Without rules:

typescript
// Cursor generates this
try {
  const user = await db.user.findFirst({ where: { id } });
  return user;
} catch (e) {
  // silent catch — the bug graveyard
}
👉 Available here: https://mohamedp2.gumroad.com/l/ruxmq
Drop it in your project root and Cursor starts following
your conventions immediately. No npm install, no config —
just copy the file.
What rules do you have in your .cursorrules?
Would love to see what others are doing.