A tappable prototype in a week, or the idea was too big

The fastest way to waste a month is to spend it designing an app you have never held. Screens look great in Figma and fall apart the moment your thumb has to reach the top of a 6.7 inch phone. So I gave myself one rule, and it has survived every project since: a working prototype on a real device within a week.

It starts with a one-page brief

Before any code, I write a single page: what the app does, who it is for, and (the important part) what gets cut. The cuts are the brief. An app that does one thing on day seven is a prototype. An app that tries to do five things on day seven is a slide deck.

“If I cannot get it onto my phone in a week, the idea was too big, not the week too short.”The rule, stated plainly

The stack is boring on purpose

React Native and Expo on the front, Firebase on the back. I reach for the same tools every time precisely so the first week is about the idea, not about wiring. Expo dev client and TestFlight mean the thing is on a real phone in hours, not days, and I can hand it to someone who is not me.

1. Day one to two: the one screen that is the whole point of the app.
2. Day three to four: the data behind it, with Firebase security rules scoped per user from the start.
3. Day five to six: the rough edges that make it feel real (empty states, a loading spinner, one good animation).
4. Day seven: it is on my phone, and I use it like a user would.

Then it is weekly loops

After week one the rhythm is short loops and ruthless cuts. Backend grows in parallel: Cloud Functions for anything sensitive (AI calls, account deletion, purchase verification), never trusted to the client. By the time the app is ready to submit, the legal pages are already drafted from the real data flow, because I have known that flow since week one.