I Used AI for Code Review on a Production ERP for 6 Months. Here's Where It Actually Failed Me.

Six months ago I started running every non-trivial piece of code through AI before it shipped. Not prototypes — real ERP and CRM modules with paying clients on the other end. Batch processing tables, MRP allocation logic, dynamic invoice builders, real-time dashboards.

Here's what I found out.

What AI is actually good at

Duplicate functions. In a codebase that's been touched by multiple devs over months, this is AI's most reliable win. It flagged things like: "This mirrors formatCurrency in utils/formatters.ts" — the kind of thing that slips through human review because everyone assumes someone else already checked.

Calculation bugs in self-contained utilities. Off-by-one errors, wrong operator precedence, bad unit conversions — if the function is isolated and doesn't depend on external state, AI catches these consistently. In ERP systems, a broken landed cost formula or tax calculation is instant client trust damage. AI has saved me here more than once.