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
overnoverVBT
BarbellVBT measures real-time barbell velocity (m/s)
$9.99
PRICE
$9.99
No 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's included16 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 overnoverVBT: 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
Incorporate social challenges and leaderboards to enhance community involvement.
Assumption to check: Lack of user engagement features like social sharing or challenges
Validate with people who use this workflow before building.
Hypothesis 2
Allow users to create and customize their own workout plans.
Assumption to check: Limited workout variety or customization options
Validate with people who use this workflow before building.
Hypothesis 3
Integrate with HealthKit and Google Fit for seamless tracking.
Assumption to check: No integration with wearables or health apps
Validate with people who use this workflow before building.
Hypothesis 4
Design an interactive onboarding process to guide users through app features.
Assumption to check: Poor onboarding experience
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
BarbellVBT measures real-time barbell velocity (m/s) using your Apple Watch accelerometer — bringing professional Velocity-Based Training (VBT) to everyone. No expensive dedicated devices needed. Just your Apple Watch. 【Scientifically Validated】 A 2023 study by the Swiss Federal Institute of Sport (SFISM) and ETH Zurich confirmed that the wrist-worn Apple Watch achieves barbell velocity measurement accuracy (r = 0.952–0.965) equivalent to professional VBT devices. (Achermann et al., Sports 2023, DOI: 10.3390/sports11070125) 【Key Features】 Real-Time Barbell Velocity Measures vertical barbell velocity in real-time using Apple Watch sensors. Displayed simultaneously on iPhone speedometer. 8 Exercise Modes Squat, Bench Press, Deadlift, Overhead Press, Snatch, Clean, Kettlebell, and Custom mode. Automatic Velocity Zone Classification Automatically displays Power, Dynamic, SPD-STR, Strength, and Max Strength zones based on measured velocity. Athlete History Management Manage training data for multiple athletes individually. Records peak velocity, rep count, and velocity loss per set. Ready Alert System Detects stillness and notifies you when measurement is ready via haptic feedback. Velocity Loss Monitoring Calculates real-time velocity loss compared to the first rep in a set, providing an objective measure of fatigue. 【Supported Devices】 iPhone (iOS 16 or later) Apple Watch Series 4 or later (watchOS 9 or later) 【What is VBT?】 Velocity-Based Training is a scientific training method that adjusts training intensity based on barbell movement speed. A method used by elite athletes — now accessible to everyone. 【Update Roadmap】 v1.0 (Current) Real-time Apple Watch velocity measurement 8 exercise modes Athlete history management Coach mode v1.1 (Next Quarter) Apple Watch Standalone Mode — Record workouts with Watch only, no iPhone needed — Auto-sync when iPhone is connected v1.1 Training Game Mode — Gamified training to hit target velocity zones — Speed challenges and performance rankings v1.2+ (User Feedback Updates) Load-Velocity Profile Automatic 1RM prediction Session trend graphs Price increases with each update. Now is the best time to start at the lowest price.
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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
Axios
React Navigation
Async Storage
React Native Reanimated
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.
