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
Onyx: Pitch Pipe
Start off on the right note every time with Onyx
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.2
70 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 should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
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 Onyx: Pitch Pipe: map the core Music 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
Introduce a wider range of pitches and custom tunings.
Assumption to check: Limited pitch options compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Optimize audio playback for faster response.
Assumption to check: Occasional audio lag
Validate with people who use this workflow before building.
Hypothesis 3
Add animations or indicators when sounds are played.
Assumption to check: Lack of visual feedback when playing sounds
Validate with people who use this workflow before building.
Hypothesis 4
Simplify the purchase process with clearer benefits.
Assumption to check: In-app purchase frustrations
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
Start off on the right note every time with Onyx. This beautiful pitch pipe sports a three-octave range in C-C or F-F, with your choice of carefully crafted sounds: choose piano or clarinet to hear your note for several seconds, or switch to continuous playback mode* to loop strings or horns for as long as you like. Or, for pinpoint accuracy, use our custom sine wave generator instead and avoid those annoying loud pops that other apps can create. On iOS, all sounds can be tuned to your preferred frequency (due to technical limitations fine tuning is only available when using the Tone sound option on Apple Watch). Use the interactive widget and the watch app for instant access from just about anywhere. Onyx even works when your device is in silent mode, so you don't have to worry about embarrassing interruptions. That's our pitch, now find yours! * Continuous playback mode is currently only supported within the app and cannot be used with the Today View widget or on Apple Watch.
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
Zustand
expo-av
react-native-gesture-handler
expo-permissions
BUILD KIT DIFFICULTY
Starter
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.
