What it is
Every form field and every request your app receives is something a person typed, or something a program sent. Checking it before using it is called validation: is the email actually an email, is the quantity a whole number, is the text short enough, is this field even something the user is allowed to set.
AI tools tend to write the happy path. The field expects a number, so the code assumes it got one. When it gets something else, the best case is a crash. The worse cases are data that’s wrong from then on, or typed input that the app treats as a command. That’s how break-ins work.
What it looks like from your side
Odd records: a customer with a blank name, an order for negative three items, a date in the year 20233. Pages that crash for one specific user. Or a field that was only meant for you, like a user’s role or a product’s price, that turns out to be changeable from the sign-up form.
What it costs if you ignore it
Bad data is expensive because it spreads. A wrong price on one order feeds into reports, invoices and refunds. A missing check on a hidden field can let a user make themselves an admin or set their own price. And unchecked input reaching your database is the classic way attackers read or destroy it.
How to check it yourself in 30 seconds
- Open a form in your app, any one that saves something. Try a few wrong answers: letters in a number field, a negative quantity, a date that doesn’t exist, a very long piece of text pasted into a short field. Submit.
- You should see a clear error and nothing saved. If the app saves it, crashes, or shows a blank screen, that’s the finding.
- Open your sign-up or profile page and press F12, or Cmd+Option+I on a Mac. Click the tab called Network, which lists what the page sends and receives. Save the form, then click the new line that appears and look for a section called Payload or Request. If you see fields you never typed, like
role,plan,creditsoris_admin, your app may be accepting whatever the form sends for them.
Use a test account. Wrong data in a real customer’s record is exactly what you’re trying to avoid.
How I fix it
Every request gets a written definition of what’s allowed: which fields, what kind of value, what range. Anything outside it is rejected with a clear message before it touches the database. Fields the user shouldn’t control are stripped out entirely.
Database instructions are built in a way that treats typed input as data, never as a command, which closes the break-in path. The definition lives next to the code, so the next AI session sees it too.
Find out before your users do.
The Production Readiness Review is $250, takes 2–3 business days, and ends with a clear verdict: fix, restructure, or rebuild.
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