Why an AI chat keeps breaking things you never touched

‘Why is AI actually so bad at building websites?’ The question came from the audience at ViennaUP, in the middle of one of my trainings.

I had to smile, because I knew exactly what the person meant. I had lived it myself.

A few weeks ago I was in a session wanting to change one small thing on a website. One line, one word, one colour. So I ask for it. The change arrives, and somewhere else something is suddenly broken. I ask again, and this time a button shifts that I never mentioned. On the third attempt a paragraph looks different that I never touched.

I sat there genuinely frustrated. This had happened to me so many times, and I had never understood why. I just kept pushing the next correction and kept wondering why it did not get better.

And then, for the first time, I stopped asking for the fix and asked for the reason. Why does this happen every single time? And it clicked. The answer is so simple that I will explain it with a house, so you never forget it.

The core difference: producing text, or working on the house

A normal AI chat writes code as text into a window. It has no real access to your file. It cannot see what is actually in there right now. It works only from what is in the conversation and from what it remembers.

So when you ask for a change, here is what happens: the model rewrites the entire file from memory. It does not take your existing work and change one line. It reconstructs the whole thing from scratch and folds your one change into it.

A tool like Claude Code does the opposite. It reads your real file, sees the exact current state, and makes a surgical change: it finds the precise spot and replaces only that. Everything else stays byte for byte identical. And afterwards it can open the result and check whether it actually holds.

The house

Picture your website as a house. It stands, you like it. Only one picture in the living room hangs slightly too far left. You want it ten centimetres to the right. Nothing more.

The normal AI chat cannot enter your house. It has no key, it is not standing inside, it cannot see the real walls. All it has is a photograph in its head, from last time. So it demolishes the whole house and rebuilds it from memory, this time with the picture in the right place.

And most of the time it looks almost the same. But the kitchen tiles have a slightly different tone. The sofa sits ten centimetres off. A window is gone. Not because it is sloppy, but because nobody can rebuild an entire house exactly from memory.

That is exactly the feeling: I changed one thing and three others broke.

The tool with the key walks into your real house, into the living room that actually exists, moves that one picture ten centimetres to the right and leaves. Everything else stays exactly as it was, down to the millimetre. Then it steps back and checks whether the picture hangs straight.

Why this happens at all, in three points

One: regenerating instead of editing. Because the model rewrites the whole file every time, it has to reproduce hundreds of lines exactly from memory. With long code that never works perfectly. Some detail you liked disappears or shifts.

Two: it cannot see the real file. If you changed something yourself in the meantime, the chat knows nothing about it. It carries on from its own last version and overwrites your change. The tool always reads the current state first.

Three: context fades. The longer the conversation, the blurrier the early details become. After thirty messages the chat no longer knows exactly what the beginning looked like, and rebuilds it slightly differently next time.

The proof in one screenshot

The image above shows a real change to the source file of one of my own blog articles, the one about my agents with no memory. All I wanted was a nicer subtitle: ‘The reports, all gone’ became ‘No trace of the reports’. The screenshot shows the German original.

Look at the line number. It is the same line 113. Only the text on it has changed. Everything else in the house is untouched. That is the whole difference.

The point in one sentence

For ‘just build me something simple’ the chat is perfectly fine. But the moment you start refining, step by step, detail by detail, you want the one that walks in and makes the one adjustment. Otherwise you spend your time repairing things that were not broken before.

And that is also the answer I gave at ViennaUP: AI does not build websites badly. It simply has the wrong tool in its hands when you ask it to rework an existing house without giving it the key.