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
PangoBooks: Buy & Sell Books
Buy, sell, and read with PangoBooks, the marketplace dedicated to book lovers.
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.9
16,791 ratings · Top 5%
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 PangoBooks: Buy & Sell Books: 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 extensive filters and category options.
Assumption to check: Limited book categories make it hard to find specific genres.
Validate with people who use this workflow before building.
Hypothesis 2
Implement a more user-friendly image upload interface.
Assumption to check: Users may face difficulties in image uploads for listings.
Validate with people who use this workflow before building.
Hypothesis 3
Create clear and simple onboarding for premium features.
Assumption to check: In-app purchasing can be confusing for users.
Validate with people who use this workflow before building.
Hypothesis 4
Integrate a chat feature for direct communication.
Assumption to check: Limited customer support options for buyers/sellers.
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
Buy, sell, and read with PangoBooks, the marketplace dedicated to book lovers. PangoBooks is the easiest way to sell and buy books affordably and sustainably. Got books to sell? Open a bookstore from your home today, list your books in minutes, and transfer your earnings directly to your bank account. Looking for books to add to your shelves? Browse millions of titles available in our marketplace, see photos of the actual book you'd be getting, and enjoy the incredible savings at checkout. OPEN YOUR OWN BOOKSTORE • List a book in minutes. • Get a prepaid shipping label as soon as you make a sale. • Transfer your earnings directly to your bank account. BUILD A HOME LIBRARY FOR LESS • Save big on new releases and backlist titles. • Score special editions and signed copies. • Get 100% guarantee on every purchase. SUSTAINABLY SUPPORT INDIVIDUAL READERS • Our sellers are readers just like you looking for a new home for their books. • Many sellers include bonus goodies as a thank you in their packages. • Get notified when your favorite sellers have special discounts. Trusted by your favorite book creators, used by millions of readers across the country. Easier to use than Amazon and eBay, and more bookish than Depop and Mercari. We're PangoBooks.
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
TypeScript
React Navigation
Zustand
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.
