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
JOYscratch
JOYscratch turns your Apple Watch into a tiny, always-with-you sketchpad
$1.99 · In-app purchases
PRICE
$1.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 5.0
1 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.
Build your own version
Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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Combine features and design from your favorite apps.
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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 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 JOYscratch: map the core Graphics & Design 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
Include more advanced tools like layers, blending modes.
Assumption to check: Limited drawing tools compared to professional apps
Validate with people who use this workflow before building.
Hypothesis 2
Implement clear save prompts and tutorials.
Assumption to check: Users may find artwork saving confusing
Validate with people who use this workflow before building.
Hypothesis 3
Create a platform for users to share their work and receive comments.
Assumption to check: No community features for sharing and feedback
Validate with people who use this workflow before building.
Hypothesis 4
Optimize file handling for smoother performance.
Assumption to check: Performance issues with large files
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
JOYscratch turns your Apple Watch into a tiny, always-with-you sketchpad. Draw with your finger, scroll the canvas with the Digital Crown, and flick your wrist to undo. No fiddly menus needed! FEATURES • Draw naturally with your finger on a smooth canvas • Pick from a palette of colors, or dial in a custom one • Three brush sizes plus an eraser • Scroll up and down for more room with the Digital Crown • Flick your wrist to undo your last stroke • Switch between black and white backgrounds • Save your drawings and reopen them anytime from your library • Add the JOYscratch complication to your watch face for one-tap access Everything stays on your device. No accounts, no tracking, no data collection. Just open it and draw! Sketch an idea, jot a shape, or just doodle for fun. JOYscratch is the quickest way from "I want to draw something" to drawing it.
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
AsyncStorage
react-navigation
react-native-canvas
expo-image-picker
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.
