# 3 founders showed me what they built with Cursor

By Venus Paneliya, full-stack AI engineer. Category: SaaS. Originally posted on LinkedIn.

3 founders showed me what they built with Cursor this month.

All 3 had working products.

Login worked. Dashboards loaded. Features functioned.

All 3 had the same 2 problems hiding underneath.

- Problem 1: Authentication looked complete but wasn’t.

The login screen worked.

But none of the three apps handled:

- What happens when a token expires mid-session.
- When the same user logs in from two devices.
- When someone manually edits a JWT in their browser.

These aren’t edge cases.

They’re Tuesday afternoon for any app with paying users.

- Problem 2: Payment failures were invisible.

All three had Stripe integrated.

Charges went through.

But none of them had logic for what happens when a charge fails.

- No retry.
- No webhook verification.
- No dunning flow.

One founder told me, “Stripe handles that.”

It doesn’t.

Stripe processes the payment.

Your app decides what happens when it fails.

Here’s what’s worth knowing.

AI tools build the happy path beautifully.

The screen where everything goes right.

But production software is 70% about what happens when things go wrong.

- Token expires.
- Payment fails.
- API times out.
- User submits garbage data.
- Two people edit the same record simultaneously.

That’s where products break.

And that’s what AI-generated code consistently skips.

The fix isn’t “don’t use AI tools.”

The fix is:

- Have someone review the output specifically for failure scenarios before you launch.

Have you built anything with AI tools?

What broke first?

Canonical: https://venuspaneliya.com/writing/what-cursor-apps-skip/