I locked my AI's design output with JSON. It worked perfectly — and everything looked like a spreadsheet

Mass-produce web tools with an AI agent and you will hit this wall: the design drifts on every generation. Same instructions, subtly different colors, spacing, and component shapes each time. Running 600+ tools in five locales, I went through three distinct eras of trying to lock the design down. Each era had a failure worth writing down.

Era 1: define the UI in JSON → it locked. And then

First attempt: define each tool's UI as JSON and generate the page from it. Scope: simple calculator-type tools with no image preview. Labels, inputs, outputs as JSON values, rendered through a fixed pipeline.

As a locking mechanism, it worked. What's in the JSON is what renders — generation-to-generation drift: gone.

But the screens came out lifeless. Straight lines everywhere, not a curve in sight. Every value sitting in its own little cell. To put it bluntly: it looked like a spreadsheet.