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
World of Books App
Discover the World of Books app!
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 3.6
55 ratings · Top 50%
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 included18 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 World of Books App: map the core Books 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
Implement personalized recommendations based on user preferences.
Assumption to check: Limited book discovery features
Validate with people who use this workflow before building.
Hypothesis 2
Optimize search algorithms for faster results.
Assumption to check: Search functionality can be slow
Validate with people who use this workflow before building.
Hypothesis 3
Adopt a minimalist design approach for improved usability.
Assumption to check: User interface can feel cluttered
Validate with people who use this workflow before building.
Hypothesis 4
Allow users to download books for offline reading.
Assumption to check: No offline access to books
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
Discover the World of Books app! Ready to dive into the magic of preloved books? Download our app to explore, shop, and rehome your favourite reads all in one easy-to-use space. Join us in giving millions of books a second life each year. Your go-to book nook, anytime Shop our ever-growing collection of books, with FREE delivery straight to your door. We’re here to make it easy to find your next favourite story! Simpler browsing and search Enjoy smooth scrolling, advanced search, and filters galore to pinpoint exactly what you’re in the mood for. Because finding that perfect read should be half the fun! Snag exclusive offers just for you! Unlock discounts, score special deals including our Buy 3, Get Another Free offer, and discover thousands of gems at prices that make your bank account happy. A checkout that’s fast & fuss-free With Apple Pay, Shop Pay, PayPal, and secure card payments, your checkout is as quick and easy as your book browsing.
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
Supabase
React Navigation
Zustand
React Native Reanimated
BUILD KIT DIFFICULTY
Expert
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.
