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
BeatLayer - Running Metronome
BeatLayer plays a metronome beat ON TOP of your music — not instead of it.
$1.99 · In-app purchases
PRICE
$1.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 5.0
3 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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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 BeatLayer - Running Metronome: map the core Health & Fitness 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
Offer a variety of sound packs or customizable sounds.
Assumption to check: Limited sound options for metronome clicks
Validate with people who use this workflow before building.
Hypothesis 2
Add social sharing options to connect with friends.
Assumption to check: No social features to share progress
Validate with people who use this workflow before building.
Hypothesis 3
Provide detailed statistics and performance analysis.
Assumption to check: No advanced analytics for running sessions
Validate with people who use this workflow before building.
Hypothesis 4
Clearly outline benefits of premium features to justify the cost.
Assumption to check: Subscription model without clear value
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
BeatLayer plays a metronome beat ON TOP of your music — not instead of it. Most metronome apps hijack your audio. You're forced to choose: rhythm or music. BeatLayer mixes a crisp beat with whatever you're already listening to. Spotify, Apple Music, Apple Podcasts, Pocket Casts — everything keeps playing. Set your target BPM, hit play, and start running. Your music stays. Your cadence improves. — FREE FEATURES — • Adjustable BPM (100–220), remembered between sessions • 6 beat sounds: woodblock, drum, electronic, tick, snap, bass • Independent volume — mix beat and music to taste • Background playback — works with any audio app • Lock-screen ready — keep running, beat keeps going — PRO ($1.99 one-time, no subscription) — • Smart Progressive Mode — gradually raise BPM during your run, adapting to your real-time cadence • 100% Ad-Free Focus — zero interruptions from start to finish
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
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.
