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
LunaSolCal
Calculate times of sunrise, sunset, moonrise, moonset and more for your location at any given date.
$4.99
PRICE
$4.99
No in-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.9
1,177 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 included15 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 LunaSolCal: map the core Utilities 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
Allow users to save multiple settings and preferences.
Assumption to check: Limited customization of location settings
Validate with people who use this workflow before building.
Hypothesis 2
Implement local data caching to enhance usability without internet.
Assumption to check: No offline functionality
Validate with people who use this workflow before building.
Hypothesis 3
Add animated visualizations for a more dynamic user experience.
Assumption to check: Static sun/moon visualization
Validate with people who use this workflow before building.
Hypothesis 4
Introduce sharing options for sun/moon data on social media.
Assumption to check: Lack of user engagement features
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
Calculate times of sunrise, sunset, moonrise, moonset and more for your location at any given date. The following data is calculated: - Sunrise - Solar noon - Sunset - Day length - Equation of time - Declination - Civil twilight (Dawn/Dusk) - Nautical twilight (Dawn/Dusk) - Astronomical twilight (Dawn/Dusk) - Azimuth at sunrise and sunset - Altitude during solar noon - Sun track - Date and time of Seasons (Spring, Summer, Fall, Winter) - Solstice and Equinox dates - Date and time of next solar eclipse - Moonrise - Moon transit - Moonset - Moon phase - Distance - Declination - Date and time of next new moon - Date and time of next full moon - Azimuth at moonrise and moonset - Altitude during moon transit - Moon track - Date and time of next lunar eclipse Some information for the current day can also be viewed in the notification center. To specify the location of interest either get the position from the built-in GPS or Wifi receiver or select a city from a database with over 400,000 cities in over 200 countries.
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
react-navigation
react-native-chart-kit
expo-linear-gradient
zustand
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.
