The app learns to measure without spying

With the app now working end to end, a question came up that doesn’t have a comfortable answer: to know what to improve, I need to understand what people use and what they don’t — what gets searched, what gets opened, where someone gets stuck. But measuring that carelessly is exactly what you promise people you won’t do when you tell them their privacy is respected.

The rule I set for myself was easy to state and harder to hold to: you can know that someone searched for something, never who they are or exactly what they typed if that could identify them. Whoever asks not to be tracked — the browser’s “do not track” signal — simply leaves no trace at all, not even a partial one. What does get stored has a real expiration date, not a promise in a document nobody enforces. And all of this had to hold up not just in the calm laptop demo, but with real traffic arriving in bursts, without losing events or falling over.

With that working, it was time to go back to the catalog: the list of things Nada Menos compared was still shorter than what people actually buy in a real week.