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
Co–Star Personalized Astrology
Co–Star is the astrology app that deciphers the mystery of human relations through NASA data and biting truth
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.8
205,802 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 Co–Star Personalized Astrology: 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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App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
Screenshots
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App Store description
Co–Star is the astrology app that deciphers the mystery of human relations through NASA data and biting truth. 2x App of the Day. Featured in the New York Times, Vogue, Vanity Fair, and more. > "Good advice." New York Times > "Banging astrology app." Dua Lipa > "Connect with people about your astrology sign." Conor Oberst Features • Add friends to compare natal charts and see your compatibility. • Read personalized daily horoscopes. • Receive daily push notifications based on your horoscope for the day. • Learn how to read your entire birth chart. Premium Features • Ask the stars & get answers to your deepest, darkest questions.. • See the full natal chart of somebody who doesn’t have the app. • Get a complete personalized report on how you love and why. • For couples, Eros, a feature that gives you insight on how to navigate everyday relationship situations based on your zodiac compatibility. There are no bad zodiac signs, only complicated dynamics. Co–Star uses astrology as a framework for understanding ourselves and our relationships; a shortcut to real talk in a sea of small talk. We use NASA data to chart the exact location of the stars in real-time. This is then interpreted by real human astrologers who collaborate with AI technology to produce the birth chart and daily horoscopes you read in the app. Follow us everywhere • Instagram: https://www.instagram.com/costarastrology/ • Tiktok: https://www.tiktok.com/@costarastrology • Twitter: https://twitter.com/costarastrology Need help? Email us: [email protected] We don't do creepy stuff with your data —> costarastrology.com/privacy Terms —> https://www.costarastrology.com/terms
Written user reviews are not shown here. Check current App Store reviews >
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
Offer more features in the free tier.
Assumption to check: Limited free features for users
Validate with people who use this workflow before building.
Hypothesis 2
Provide customizable notification settings.
Assumption to check: Overwhelming notifications about daily horoscopes
Validate with people who use this workflow before building.
Hypothesis 3
Include detailed explanations for compatibility results.
Assumption to check: Compatibility results can be vague
Validate with people who use this workflow before building.
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.
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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.
