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
Mooncast
Mooncast is a beautifully crafted app showcasing the current phase of the moon with precision and clarity
$3.99 · In-app purchases
PRICE
$3.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.8
3,627 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 should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
What's included19 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
Preview a sample Build Kit No email needed
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 Mooncast: map the core Weather 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
Integrate multiple weather APIs for better accuracy
Assumption to check: Limited weather data sources can lead to inaccuracies
Validate with people who use this workflow before building.
Hypothesis 2
Allow users to set specific alerts based on weather conditions
Assumption to check: Lack of customization options for notifications
Validate with people who use this workflow before building.
Hypothesis 3
Implement local caching for offline access to saved forecasts
Assumption to check: No offline access to weather data
Validate with people who use this workflow before building.
Hypothesis 4
Offer a freemium model with basic features available for free
Assumption to check: High price point may deter users
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
Mooncast is a beautifully crafted app showcasing the current phase of the moon with precision and clarity. This app is designed for both casual curiosity and serious sky-watchers. Explore the lunar cycle in rich visual detail, swipe through days to see past and future phases, and instantly find the next full moon or new moon. Mooncast gives you accurate lunar data for any date between 2011 and 2035, including the exact moment the moon becomes perfectly full. Features: - Stunning, high-fidelity moon phase visuals - Interactive timeline — swipe to explore any day - Accurate predictions for full moons, new moons, and all lunar phases - Built-in almanac for long-term browsing and planning - Precise timestamps for peak full moon and new moon - Smart reminders for full moon and new moon events - Customizable look - pick your favorite sky and clouds - Several types of widgets and accessories are available Extensive coverage: - available on iPhone, iPad, Mac, Apple Watch and Apple TV International support: - Fully localized in English, French, Spanish, Italian, German, Russian - Works seamlessly with all locales and calendar systems Mooncast is simple to use, scientifically accurate, and visually refined — the lunar calendar you’ll actually enjoy checking every day.
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
Axios
Zustand
react-navigation
expo-location
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.
