The trouble starts the day the prototype is expected to be a product. Real users arrive, a customer asks for one small change, or an investor asks who can maintain it. The things that break at that point are surprisingly predictable. Here is the order I would check them in.

1. The data model

A prototype's database is usually whatever shape made the first screen work. Tables mirror the UI, relationships are implied rather than enforced, and the same fact is stored in two places.

It survives the demo. It does not survive the first "can we add teams?" or "can we export this?" because every feature now has to work around a structure that was never designed.

What to do: before adding anything new, sketch the real entities and their relationships on paper. Fix the schema while there is little data to migrate. Migrating later, with real customer records, is where the expensive mistakes happen.

2. Authentication and permissions

Prototypes often have a login, and that is where the thinking stopped. The harder question is authorisation: can this user see this specific record? In generated code, that check is frequently missing from some routes, because the demo only ever used one account.

What to do: list every route and every data access, and for each one write down who is allowed. Then test it with two accounts and try to read the other one's data. If you can, you have found your most urgent bug.

3. Error handling

The happy path works. Everything else is a blank screen, a spinner that never ends, or a silent failure. Generated code tends to catch errors and carry on, which keeps demos tidy and hides real faults.

What to do: make failures visible. Log them with enough context to act on, show users an honest message, and decide deliberately what should happen when a payment, an email or a third-party API fails. Those are the cases that generate support tickets.

4. Configuration and secrets

Keys in the code, hard-coded URLs that point at localhost, one environment standing in for development, staging and production. None of it matters until you deploy, and then all of it does.

What to do: move every secret and environment-specific value out of the code. Rotate anything that was ever committed. Have at least separate development and production configurations.

5. Performance with real data

A prototype with ten rows is fast. Real data exposes queries that load everything and filter in memory, pages that make a request per item, and images that were never resized. These are invisible in a demo and obvious on a slow phone.

What to do: load realistic amounts of data and look at the slowest page. Fix the worst offender first, usually a query or a missing index, and measure again.

6. Tests and the fear of changing things

The first sign of an untested codebase is not a bug. It is hesitation: nobody wants to touch the code because nobody knows what else will break. The prototype was written fast, so changing it feels risky.

What to do: do not aim for full coverage. Write tests around the few flows that must never break, such as sign-up, payment and the core feature. That gives you the confidence to change everything else.

7. Nobody can explain it

The least visible problem and the most expensive one. If the code was generated in a series of prompts, there may be no person who understands how the whole thing fits together. The first engineer you hire spends weeks working it out, or proposes a rewrite.

What to do: have an experienced developer read the whole codebase once, tidy it, and write a short document covering how to run it, how it is structured and why. That small amount of documentation is what makes the code transferable.

The honest summary

Prototype-to-production is not a rewrite and it is not a reason to avoid AI tools. It is a review pass over the seven places where speed-first code tends to be weakest. The order above is roughly the order in which they hurt.

At Sucre Studios we build fixed-scope MVPs with AI-accelerated development and expert review, so every line of AI-assisted code is read and tested by an experienced developer before it ships. If you have a prototype and are unsure how far it is from production, going through this list will tell you quickly.

Written by Lucas Shaw, founder of Sucre Studios.