Design
In short
Design settles what the app is: screens, flows, data model and architecture, running against mocked data with nothing deployed, so changing your mind is nearly free.
Design is where the app takes shape. The frontend is real and clickable; the data behind it is mocked. No servers exist yet, and no AWS costs are running.
What you do here
- Walk the screens and the flows until they match how the work actually happens.
- Settle the data model — the entities, their relationships, the words the business uses.
- Fix the architecture profile: what kind of app this is, what it integrates with, what it must never do.
- Attach the artifacts that carry intent — specs, screenshots, exports from the old system.
Why mocked data is the point
Restructuring a data model in Design costs a conversation. The same change in Build costs a migration, and in Live it costs a migration plus a maintenance window. Design is deliberately the cheap place to be wrong.
Signs you are ready to leave
- Someone who will use the app has clicked through it and recognised their job.
- The nouns are settled; you are no longer renaming core entities every session.
- You know which parts must be
//!SAFE— the areas carrying money, permissions, or regulatory weight.
What Design is not
It is not a mockup you throw away. The code written here is the app’s frontend; Build wires a real backend behind it rather than starting over.
Next: Build · Promoting between stages