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.
“FaSoLaMix” is designed to teach Sacred Harp singing to newer singers
$12.99 · In-app purchases
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.
A product spec, screen plans, and build steps for your coding agent.
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Combine features and design from your favorite apps.
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What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
A product spec, phased build plan, differentiation notes, and screen references.
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Goal: Send a clear invoice after finishing a job.
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.
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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Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
Rork plan preview for FaSoLaMix: 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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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
Assumption to check: Users find the mixing interface overwhelming.
Validate with people who use this workflow before building.
Hypothesis 2
Assumption to check: Limited track library.
Validate with people who use this workflow before building.
Hypothesis 3
Assumption to check: In-app purchase confusion.
Validate with people who use this workflow before building.
Hypothesis 4
Assumption to check: Performance issues with large mixes.
Validate with people who use this workflow before building.
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
“FaSoLaMix” is designed to teach Sacred Harp singing to newer singers. When someone wants to learn to sing, our instinct is usually to recommend that the inquirer go to a good singing and sit next to a strong singer. But not everyone lives near many all-day singings. Our intent is to give the listener the virtual experience of sitting next to a couple of strong singers in whichever section suits their voice. The app features high-quality recordings of many Sacred Harp songs where the mix of the four parts can be controlled manually. For example, a singer wanting to learn the treble line of a particular song could leave the treble track at full volume, mute the other three parts, and sing along with the solo treble part for practice. While the most obvious benefit will be to new singers, longtime singers will also find it useful and fun. For example, experienced singers may wish to mute one part and fill in that missing part with their own voice. This app comes bundled with recordings of 35 songs, ranging in difficulty, all of which are regularly called at all-day singings and conventions. More recordings will become available for sale periodically in the form of “song packs” which will generally include several songs. Songs included: 30t LOVE DIVINE 36b NINETY-FIFTH 56t COLUMBIANA 65 SWEET PROSPECT 68b ORTONVILLE 84 AMSTERDAM 87 SWEET CANAAN 89 THE CHURCH’S DESOLATION 99 GOSPEL TRUMPET 101t CANAAN'S LAND 112 THE LAST WORDS OF COPERNICUS 155 NORTHFIELD 176b BLOOMING YOUTH 178 AFRICA 182 NEWBURGH 192 SCHENECTADY 196 ALABAMA 198 GREEN STREET 200 EDOM 216 DELIGHT 276 BRIDGEWATER 277 ANTIOCH 282 I’M GOING HOME 318 PRESENT JOYS 349 A CROSS FOR ME 384 PANTING FOR HEAVEN 411 MORNING PRAYER 436 MORNING SUN 440 NORTH SALEM 448b THE GRIEVED SOUL 456 SACRED MOUNT 472 AKIN 480 REDEMPTION 542 I’LL SEEK HIS BLESSINGS 546 MY BRIGHTEST DAYS All songs from The Sacred Harp, 1991 “Denson” Revision, used by permission of its publisher, the Sacred Harp Publishing Company, Inc., Carrollton, GA. The developers of this app in no way personally profit from the sale of this app. All proceeds will be used to prepare more recordings for future updates with excess used to support the Sacred Harp Musical Heritage Association, a 501(c)(3) non-profit organization whose purpose is the preservation and perpetuation of Sacred Harp singing and its traditions.
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Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
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.