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
iStellar
iStellar is a planetarium App that shows the starry sky seen from the place and time of your choice
$3.99 · In-app purchases
PRICE
$3.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.0
1 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 included18 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 iStellar: map the core Navigation 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 in-depth information and visuals.
Assumption to check: Limited celestial object details compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Add social features for users to share their findings.
Assumption to check: No community features for sharing discoveries
Validate with people who use this workflow before building.
Hypothesis 3
Enhance performance optimization for smoother experience.
Assumption to check: Inconsistent performance in real-time tracking
Validate with people who use this workflow before building.
Hypothesis 4
Offer a free trial or freemium model to attract more users.
Assumption to check: High price compared to similar apps
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
iStellar is a planetarium App that shows the starry sky seen from the place and time of your choice. It is optimized for Multi-Touch control, allowing you to operate intuitively; drag to move the star chart, pinch to zoom in and out, and so on. The star chart can be rotated from portrait to landscape, and you can even fix the location via GPS (only for iPhone 3G). FEATURES - Over 16,000 star data, with name for 254 stars - Twinkles like actual stars - Simulates distortion (atmospheric refraction and extinction) at low altitude - Displays the Sun, daylight, twilight, the Moon (with shape and phase), 8 planets, Pluto - Shows name, line and picture for all constellations - Milky Way with real tone - Plots Messier objects and their names - Comets with accurate position and magnitude. Data can be downloaded whenever available - Meteor Shower Radiants - Solar eclipse simulation with high accuracy - Adjustable moonlight and light polution - Landscape and azimuth / direction grid - Beautiful animation (real-time, adjusted time, reversal) - Simulates every second between 1 Jan 1900 to 31 Dec 2099 - Switches screen according to the device's orientation - Zoom by pinching(3 to 180 degrees) - Easy moving through the sky by dragging, and centering by double-tap - Object Search function - Free choice of location and time zone, instant setting with GPS
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
axios
expo-maps
react-native-gesture-handler
BUILD KIT DIFFICULTY
Advanced
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.
