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
I Ching: Book of Changes
For years the #1 I Ching app in the world, and perhaps the most elegant, distilled version of the I Ching there is
$7.99 · In-app purchases
PRICE
$7.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.9
1,993 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 I Ching: Book of Changes: map the core Lifestyle 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
Provide more detailed interpretations and insights.
Assumption to check: Limited explanation for each hexagram
Validate with people who use this workflow before building.
Hypothesis 2
Implement better navigation options and history tracking.
Assumption to check: Difficult navigation to previous readings
Validate with people who use this workflow before building.
Hypothesis 3
Allow users to save favorite readings or hexagrams for quick access.
Assumption to check: Lack of personalization
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
For years the #1 I Ching app in the world, and perhaps the most elegant, distilled version of the I Ching there is. For centuries, the Book of Changes has been consulted for sage advice at life's turning points. When its wisdom is sought with sincerity and sensitivity, this ancient Chinese oracle will promote success and good fortune and impart balance and perspective to your life. Its lasting popularity lies in the profound lessons it teaches about how reliance on one's higher qualities leads to life's greatest rewards: well-being, understanding, and peace of mind. Now available as an elegantly designed and easy to use iOS app, it is both highly accessible to new users and a revelation to those long familiar with the text. Throw your own coins, or let the app cast for you, and make the wisdom of the sages your own. Includes a journal for recording your questions, results, and thoughts. Brian Browne Walker is the author of celebrated contemporary translations of the I Ching, Tao te Ching, Hua hu Ching, Wei wu Wei Ching, and Art of War which are published by Harper and St. Martin's Press and translated into over a dozen languages around the world. His "I Ching, or Book of Changes", long beloved for its clarity and accessibility, has received five star reviews on Amazon consistently for over a decade.
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
@supabase/supabase-js
BUILD KIT DIFFICULTY
Starter
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.
