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
KB-1 Keyboard Suite
KB-1 MIDI Keyboard
$14.99 · In-app purchases
PRICE
$14.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.8
263 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's included18 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 KB-1 Keyboard Suite: 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 instrument selection and customization options.
Assumption to check: Limited instrument variety compared to physical keyboards.
Validate with people who use this workflow before building.
Hypothesis 2
Enhance recording features with easier sharing options.
Assumption to check: Difficulties in recording and sharing music.
Validate with people who use this workflow before building.
Hypothesis 3
Offer more trial features to attract users.
Assumption to check: High price point may deter users.
Validate with people who use this workflow before building.
Hypothesis 4
Include tutorials and tips for beginners.
Assumption to check: Limited educational resources.
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
KB-1 MIDI Keyboard KB-1 is a suite of expressive virtual keyboards and controllers designed for a multitude of scenarios. Play multiple instruments simultaneously, complete with MIDI Polyphonic Expression, scales, chords, strumming and more. Overview: - 8 distinct Keyboard Layouts - Multiple Rows per Keyboard - Multiple Octaves per Keyboard Row - 15+ Scales (for layouts that support scales) - MIDI Polyphonic Expression (MPE) - Powerful Arpeggiator - Standalone operation with multiple Keyboards and dedicated MIDI outputs per Keyboard - AUv3 MIDI Plugin Layouts: - Classic (Piano Keys + Wheels) - Uniform (Seboard-style Keys and Layout) - String (String-style Keys) - Scale (Uniform layout with scale support) - Chord (One key per chord for all scale degrees) - Drum (up to 16 user mappable drum pads) - XY (up to 2 configurable XY-Pads) - CC (up to 16 user mappable knobs for CC control) Expression: - Glide (horizontal) - Slide (vertical) - Velocity (mapped to y-axis) - Pressure (iPhone only) App Connectivity: - Standalone - AUv3 MIDI Instrument MIDI Connectivity: - Inter-App MIDI - USB MIDI - BLE MIDI - Network MIDI
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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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.
