A starting prompt
Paste this into the builder and change the names, rules and colours to yours. It produces a working first version; everything after is refinement.
Two kinds of fitness app
There is the tracker — habits, water, sleep, workouts logged after the fact — and the trainer — timed routines you follow live. The AI handles both; it just needs to know which one you mean, because the home screen is different. A tracker's home is "today's list, tap to complete". A trainer's home is "pick a routine, press start".
Say "habit tracker" or "workout timer" in the first sentence and the builder generates the right shape without a back-and-forth.
What the builder generates
For a tracker: a Today screen with large touch targets, an editor with a picker for icon, colour, weekdays and reminder time, and a Stats screen with a per-habit heat-map (a 7×12 grid of coloured cells) plus current and best streak. Data is stored locally in the app; ask for "export to CSV" if you want a backup button.
For a trainer: a routine list, a routine editor (exercise, duration or reps, rest), and a full-screen timer with big numbers, a progress ring and a vibration at each transition. The vibrate capability is native and gets declared automatically.
Reminders that work
Reminders are the difference between a tracker and a to-do list nobody opens. Each habit's reminder time becomes a scheduled local notification. On modern Android the app has to ask for notification permission once; the generated app does this the first time you save a habit with a reminder rather than at launch, which is what Google recommends and what keeps people from tapping "Don't allow".
Keeping it yours
Trackers are personal, and a good prompt says so: "no account, no sign-up, everything stays on the phone". The builder will skip any login screens and the exported project will have no network permission at all, which is a selling point on the Play listing.