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
Whistle Blow
Blow Whistle turns your iPhone into a crisp, realistic whistle, no hardware needed
$0.99 · In-app purchases
PRICE
$0.99
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 included17 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
Preview a sample Build Kit No email needed
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 Whistle Blow: map the core Sports 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
Add features for team management and collaboration.
Assumption to check: Limited functionality for managing multiple teams.
Validate with people who use this workflow before building.
Hypothesis 2
Integrate messaging or community forums.
Assumption to check: Lack of social features for coaches to connect.
Validate with people who use this workflow before building.
Hypothesis 3
Implement analytics for session performance.
Assumption to check: Difficulty tracking session progress and outcomes.
Validate with people who use this workflow before building.
Hypothesis 4
Enhance notifications for session reminders and updates.
Assumption to check: Inadequate notification system.
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
Blow Whistle turns your iPhone into a crisp, realistic whistle, no hardware needed. Trigger it your way: blow into the mic, shake your device, tap the screen, or remotely trigger it from your Apple Watch. Perfect for getting attention, coaching, pranks, or quick sound effects. Dial in exactly how you want it to respond with adjustable microphone sensitivity and full volume control. Pick your favorite whistle sound and, if you like, display a live mic level meter for visual feedback. Features: - Blow-to-whistle with adjustable mic sensitivity - Tap or shake to trigger—no mic required - Apple Watch support: trigger from your wrist - Choose from multiple whistle sounds - Volume control for any environment - Optional on-screen mic level meter - Works offline, lightweight, and fast Privacy-Friendly: - Microphone access is only used for the blow-to-whistle feature. You can still tap, shake, or use Apple Watch without granting mic permission. Note: Blow Whistle is for fun and everyday use. It is not a substitute for safety devices or emergency signaling. Compatibility: - iPhone and iPad - Apple Watch (requires paired iPhone)
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 Navigation
TypeScript
Firebase
BUILD KIT DIFFICULTY
Starter
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.
