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
CarMax: Used Cars for Sale
Welcome to the CarMax app
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.8
407,676 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 included18 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 CarMax: Used Cars for Sale: 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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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
Enhance search functionality with advanced filters like year, condition, and location.
Assumption to check: Limited search filters compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Implement a verification process for sellers to ensure higher quality listings.
Assumption to check: Inconsistent car listing quality
Validate with people who use this workflow before building.
Hypothesis 3
Add a review system for sellers to build trust and transparency.
Assumption to check: Lack of user reviews for sellers
Validate with people who use this workflow before building.
Hypothesis 4
Offer more flexible payment methods for premium features.
Assumption to check: Limited payment options for contacting sellers
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
Welcome to the CarMax app. Designed to make your next car journey more convenient, whether you’re buying with us, scheduling a test drive or paying off your loan. Download and get started today! CARMAX APP FEATURES: Find the right car for you: • Save time searching with a nationwide inventory of 40,000+ used cars, SUVs, and trucks. • See car details and interior and exterior photos. • Ship vehicles to your closest store and schedule a test drive at your convenience. Customize your search: • Favorite cars and save searches. • Get alerts for changes to your saved cars and favorites. On My Way: · Alert us when you are leaving for your appointment, and our associates will be ready for your arrival. Shop around from one place: · Shop cars in our nationwide inventory · Get free vehicle history reports · Get pre-qualified · Make financing payments At CarMax, we’ve got your back. That’s why we offer: 1. Discounts directly from the app for customers who buy with us. 2. Upfront prices, clearly marked on every car. Download the CarMax app now and find your next used car, whether you’re on the lot or on the go.
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.
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Zustand
BUILD KIT DIFFICULTY
Expert
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.
