Feature spec
Goal: Send a clear invoice after finishing a job.
- Add a client, line items, a due date, and payment instructions.
- Preview the total before exporting a PDF.
- Keep an editable draft if export fails.
App Overview
Adrian James: HIIT
Adrian James High Intensity Interval Training is the fat-burning workout that’s become an international hit
$3.99 · In-app purchases
PRICE
$3.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.7
54 ratings · Top 15%
Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.
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Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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What's included17 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
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Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Screen plan
Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.
States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.
Differentiate and validate
Hypothesis: Contractors need faster repeat invoices more than more templates.
First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.
The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.
Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.
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Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Adrian James: HIIT: map the core Health & Fitness workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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Opportunities
AI-GENERATED OPPORTUNITY HYPOTHESES
These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.
Hypothesis 1
Offer more diverse workout types and customization options.
Assumption to check: Limited variety of workouts compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Implement more robust timer functionality with user feedback.
Assumption to check: Occasional bugs in workout timers
Validate with people who use this workflow before building.
Hypothesis 3
Add options for users to share progress and compete in challenges.
Assumption to check: Lack of social features for community engagement
Validate with people who use this workflow before building.
Hypothesis 4
Introduce a subscription model for ongoing content updates.
Assumption to check: One-time purchase model limits access to future content
Validate with people who use this workflow before building.
App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
App Store description
Adrian James High Intensity Interval Training is the fat-burning workout that’s become an international hit. Download the chart-topping app and take your fitness to the next level. Fun, fast and highly effective, Adrian James High Intensity Interval Training will release a rush of endorphins, increase your cardiovascular fitness and raise your metabolism. You can exercise anytime, anywhere - no equipment and no internet connection required. Number one in over 10 countries, Adrian James High Intensity Interval Training provides clear video tutorials with an easy-to-follow workout mode to challenge every ability level. Get motivated with the 8-week challenge and earn points for every workout you complete. Where would you like to be 8 weeks from now? If the answer is "In the best shape of my life", download the app and start today. It’s your body. Take control. App features include: • 18 graded exercises to challenge every ability • Clear video tutorials with audio commentary • Helpful tips to guide you through each exercise • Workout mode with randomised levels • Motivational quotes to spur you on • Adrian James 8-week challenge • Absolutely no gym equipment required Also available: • Adrian James 6 Pack Abs Workout • Adrian James Bootcamp
Written user reviews are not shown here. Check current App Store reviews >
Screenshots
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Build scope
Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Define the first version
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Set boundaries
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Check the hard parts
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
SUGGESTED BUILD STACK
React Native
Expo
Zustand
Axios
react-native-chart-kit
expo-video
BUILD KIT DIFFICULTY
Intermediate
From the Build Kit assessment.
A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.
