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
Moon Phases - Lunar Calendar
Discover all the phases of the Moon in real time with spectacular graphics and an intuitive lunar calendar.
$1.99 · In-app purchases
PRICE
$1.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.2
8 ratings · Top 30%
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 included16 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 Moon Phases - Lunar Calendar: 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
Add more educational content and interactive features.
Assumption to check: Limited features compared to other lunar calendar apps
Validate with people who use this workflow before building.
Hypothesis 2
Allow users to set custom alerts for moon phases.
Assumption to check: Lack of customization options for notifications
Validate with people who use this workflow before building.
Hypothesis 3
Enable syncing with Google Calendar or Apple Calendar.
Assumption to check: No integration with other calendar apps
Validate with people who use this workflow before building.
Hypothesis 4
Introduce a free trial to attract more users.
Assumption to check: Single payment model without trial
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 all the phases of the Moon in real time with spectacular graphics and an intuitive lunar calendar. "Moon Phases" is your ultimate app to always know the Moon’s current appearance, check past and future cycles, and plan precisely with reliable astronomical data. Main features: • Complete lunar cycle calendar: quickly view past and future Moon phases. • Clear visualization of lunar phases, daily percentage illumination, and much more. • Realistic moon view based on current weather conditions. • Accurate real-time lunar sunrise and sunset times. • Automatic day/night mode based on location and local time. • Create an unlimited personal list of favorite locations. • Realistic moon appearance based on Northern or Southern Hemisphere. • Polished graphics for a unique experience, with sharp images and dark mode. Who is this app for? Perfect for those who follow the Moon in astronomical observation, night photography, biodynamic farming, or are simply curious about its phases day by day. Update your way of watching the sky now! For suggestions or support, write to [email protected] or visit lionsapp.com. If you like the app, leave a review on the App Store — your feedback matters!
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 Navigation
Expo Notifications
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.
