7 AI-Generated Code Bugs You'll Never Catch in Dev (But Will Hit in Production)

Why dev and production are different worlds

In dev, you're the only user. The database is empty. APIs always respond. The network is fast. Your test data is clean. Production is the opposite: concurrent users, dirty data, slow networks, third-party failures, and adversarial inputs.

1. Race conditions in React state updates

AI writes clean-looking useEffect hooks, but under fast user interaction or React 18 concurrent mode, state updates can arrive out of order. You'll never see this in dev because you move slowly.

2. Unhandled API timeout errors

AI code almost always handles 4xx and 5xx responses. It almost never handles timeouts, network disconnects, or partial responses. Real users on mobile networks hit these constantly.

3. Integer overflow in calculations

If your app does any math on user-provided numbers, AI will typically not add bounds checks. Users will enter 999999999 and your UI will display NaN or Infinity.

4. Session token not refreshed

AI implements auth flows for the happy path. Token expiry during a session (user leaves tab open overnight) is almost never handled, causing mysterious "logged out" bugs that users can't reproduce.

5. Missing database transaction rollbacks

AI often writes multi-step database operations without proper transactions. If step 2 fails, step 1 has already committed. Data integrity issues are hard to track down without proper error monitoring.

6. Memory leaks from event listeners

AI adds event listeners in useEffect without cleanup functions. Under normal dev usage this is invisible. Under real usage with navigation and component mounting/unmounting, memory grows until the tab crashes.

7. Locale-dependent formatting bugs

AI formats dates and numbers for your locale. Users in other countries see broken displays — wrong date formats, comma vs. period in numbers, etc.

How to catch these before users do

The only reliable way is production error monitoring. ProdFix captures all of these with full context: stack trace, user session, browser, the exact state at the time of failure. And with the MCP integration, you can fix them in Cursor without ever leaving your editor.