How to build a bigger app with AI: plan first, then build in milestones
Long briefs break one-shot AI app builders. Here is how AppX now shows a plan first, builds the core screens, and adds the rest milestone by milestone.
AppX team ·
Most AI app builders are good at small apps. A tip splitter, a water tracker, a timer. You type one paragraph and you get something on your phone.
Real app ideas are rarely one paragraph. A founder pastes a two-page spec. An agency pastes the client's requirements document. A developer pastes an API guide and says "build the app on top of this". That is where one-shot builders usually break. They try to fit everything into one pass, run out of room, and hand you half an app that looks finished but isn't.
We spent the last six weeks changing how AppX handles exactly this case. This post explains the new flow and how to get the most out of it.
The problem with building everything at once
When a builder tries to create fifteen screens in one go, three things tend to happen.
First, it quietly drops things. Requirements from the bottom of the brief never make it into the app, and nobody tells you.
Second, the style drifts. The first screen has one look, the ninth screen has another, because each was written without a clear reference.
Third, one failure sinks the whole run. If screen eleven has a bug, the entire build fails, and you pay for a result you can't use.
The fix is not a bigger model. The fix is to plan first and build in steps you can check.
Step 1: describe the app, then read the plan
You still start by describing your app. A short idea is fine. A long spec is fine too. There is no minimum length anymore, so short follow-ups like "add dark mode" work as well.
Before AppX writes any code, it shows you a plan:
- The screens it will build first.
- Which screens sit in the tab bar and which open on top of it. Sign-in and onboarding screens are never placed in the tab bar.
- Which of your requirements each screen covers.
- An estimate of how many credits the build will use.
Read it the way you would read a quote from a contractor. Is the main screen the one your users will open every day? Is anything obviously missing? Is it trying to do too much at once?
Nothing is built until you press Approve plan. If the plan is wrong, press Refine plan and tell AppX what to change.
If you are not sure how to write the brief in the first place, our guide on how to describe your app to AI has a template.
Step 2: the first build covers the core
For a bigger brief, AppX doesn't try to build every screen in the first pass. It builds the core: the screens that make the app usable end to end. The rest of your requirements are kept in the plan. They are not dropped.
Before the preview goes live, AppX type-checks the whole project and repairs errors it finds. This is the step that used to fail silently. Now a broken import or a mistyped component is caught and fixed before you see the app.
If the first build still fails, you are not charged. Press Retry, and AppX rebuilds from the exact plan you approved. It does not start over from a blank message.
When the build is live, scan the QR code and open the app on your phone. Our Expo Go guide explains how phone previews work.
Step 3: add the rest, one milestone at a time
After the first build is live, a "Next milestone" card appears in the chat. It lists the screens and requirements that are still left, with a credit estimate for that milestone.
When you press Build next milestone, AppX builds those screens on top of the app you already have, from the same approved plan. Each milestone is a normal build: it goes live, you check it on your phone, and then you move on.
This has a few practical benefits:
- You see progress early. The core of your app is on your phone after the first build, not after one very long wait.
- Problems stay small. If something in milestone three needs fixing, milestones one and two are already working.
- You control the spend. Every milestone shows its estimate before it starts. If your balance is too low, AppX tells you up front instead of failing halfway.
- You decide when to stop. Milestones never start on their own. After any milestone you can stop and keep refining the app with normal chat edits instead.
The style carries across screens
A common complaint about AI-built apps is that they look generic, or that every screen looks slightly different.
AppX now gives each app a curated font, one corner-radius scale, and a colour palette tinted to the app's brand. The home screen sets the style, and later screens, including the ones added in later milestones, follow it. Photos from the web, such as Unsplash images, now load in the preview too, so photo-heavy apps like recipe or travel apps look the way they should.
Small edits stay small
Once the app exists, most of your requests will be small: "make this button green", "rename this tab", "add a date to each card". AppX now applies these as targeted changes to the exact lines involved instead of rewriting whole files. They finish faster, and they are less likely to break something else.
If an edit goes wrong, you can restore an earlier saved version of your code.
What this looks like in credits
Credits depend on the size of the app. Two real examples from our own builds: a 5-screen recipe app (Crumbs) used 29 credits, and a 2-screen water tracker (SipDay) used 16 credits. New accounts start with 100 free credits every month, and the plan shows its estimate before anything runs.
What this does not change
Plan-first building makes bigger apps possible. It doesn't make them automatically finished. A few honest limits:
- A live preview is not a store-ready app. Before real users touch it, go through our 12-point launch checklist.
- The plan is only as good as the brief. If a requirement is vague, the screen will be vague too. Fix it in the plan, not after five milestones.
- You still own the result. Download your full code as a ZIP on any plan, and hand it to a developer whenever you want.
Try it with your own brief
Take the longest description of your app you have, whether it's a spec, a client document, or a messy notes file, and paste it into AppX. Read the plan, approve it, and get the core of your app on your phone. Then build the rest one milestone at a time.
Evidence note: the features in this post are live on appx.uz as of September 27, 2026. See the changelog for the full list. Credit examples are the same figures shown on the AppX pricing page.