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
GyroSynth
GyroSynth is a gesture driven music synthesizer, which takes full adventage of the gyroscope
$4.99 · In-app purchases
PRICE
$4.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.4
37 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 included15 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 GyroSynth: 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
Expand the library with more unique instruments.
Assumption to check: Limited instrument selection.
Validate with people who use this workflow before building.
Hypothesis 2
Implement tutorials or onboarding to guide users.
Assumption to check: Gestures can be hard to master.
Validate with people who use this workflow before building.
Hypothesis 3
Add options for users to share their creations on social media.
Assumption to check: No social sharing features.
Validate with people who use this workflow before building.
Hypothesis 4
Enable offline music creation and storage.
Assumption to check: No offline functionality.
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
GyroSynth is a gesture driven music synthesizer, which takes full adventage of the gyroscope. You can play and modulate the sound by moving your hand through the air - just like the legendary Theremin instrument. GyroSynth makes use of the gyroscope to measure true roll, pitch, and yaw and translates them to sound parameters like pitch, volume, modulation or filter cutoff. Thanks to phenomenal accuracy (2000 degrees), you can play melodies perfectly in tune. A finalist in 'Most Innovative App' category at the 2010 Best App Ever Awards (148apps). GyroSynth has been used in numerous live jams and performances (e.g., Mindex) FEATURES - Synthesizers: vocal (formant synthesizer), sine wave , square (PWM modulation), saw, granular sample player with recording function and R2D2 - experimental FM modulation - Effects: delay and boost - Several control modes - Included musical scales allow you to effortlessly play in several styles - Built-in recorder and player with overdub function "There isn’t too much more to say about GyroSynth other than wow!" AppSafari Enjoy the new experience!
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
react-native-reanimated
expo-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.
