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
Echo Cube - Acoustic Delay
Echo Cube is a dual delay inspired by the Cooper Time Cube, a rare analog unit that created echo using long coiled tubes instead of tape or electronic circuits
$8.99 · In-app purchases
PRICE
$8.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
N/A
No ratings yet
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 included14 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 Echo Cube - Acoustic Delay: 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
Implement user reviews and ratings for presets.
Assumption to check: Limited user feedback on presets
Validate with people who use this workflow before building.
Hypothesis 2
Provide preset suggestions for beginners.
Assumption to check: Complexity of audio settings may overwhelm users
Validate with people who use this workflow before building.
Hypothesis 3
Add social sharing features for presets.
Assumption to check: Difficulties saving and sharing presets
Validate with people who use this workflow before building.
Hypothesis 4
Integrate visualizers to show effects in real-time.
Assumption to check: No visual representation of audio effects
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
Echo Cube is a dual delay inspired by the Cooper Time Cube, a rare analog unit that created echo using long coiled tubes instead of tape or electronic circuits. The delay time was defined by the physical travel of sound through air. Echo Cube recreates and expands this concept with two independent delay lines, each with time, feedback, and level controls. Choose between Time Cube for authentic hardware tone, or the experimental Garden Hose and Corrugated models for creative sound design. Flexible routing modes including serial, parallel, ping pong, mono sum, and mid side give you full control over delay interaction and stereo image shaping.
Written user reviews are not shown here. Check current App Store reviews >
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
react-navigation
expo-av
@react-native-async-storage/async-storage
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.
