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.
Improve self-regulation and better cope with stress using HRV4Biofeedback, the camera-based Heart Rate Variability (HRV) Biofeedback app
$9.99 · 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.
First kit free with a verified email
Combine features and design from your favorite apps.
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Generating… usually about a minute.
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 HRV4Biofeedback: map the core Lifestyle 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 report difficulty in understanding how to interpret HRV scores.
Validate with people who use this workflow before building.
Hypothesis 2
Assumption to check: Limited variety of exercises available.
Validate with people who use this workflow before building.
Hypothesis 3
Assumption to check: App has occasional bugs during measurement.
Validate with people who use this workflow before building.
Hypothesis 4
Assumption to check: Subscription pricing may be perceived as high.
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.
Improve self-regulation and better cope with stress using HRV4Biofeedback, the camera-based Heart Rate Variability (HRV) Biofeedback app APP FEATURES: > camera-based biofeedback measurement showing real-time heart rate > spot check measurements at rest > frequency power spectrum > biofeedback score to quantify the effectiveness of the practice in terms of deep breathing and duration > resonant frequency analysis to determine the optimal breathing rate for your sessions > semi-real time HRV analysis > alternative manual breathing rate configuration between 4.5 and 8.5 breaths / minute > subjective annotations, including up to 5 personalized questions > current streak > explore correlations between subjective annotations and biofeedback data > Integration with HealthKit (you can write heart rate, HRV and Mindful minutes) > weekly and monthly summaries > support for Bluetooth sensors > background nature sounds > vibration to guide you through the practice WHAT'S BIOFEEDBACK? Heart Rate Variability (HRV) Biofeedback is a technique that can directly affect physiological and psychological factors through deep breathing exercises and is an ideal strategy to help us self-regulate and better cope with stressful situations Practically speaking, HRV Biofeedback consists of providing an individual with real-time feedback on instantaneous heart rate and respiration changes while being instructed to breathe at low frequencies You can learn more about the psychological and physiological benefits of deep breathing and HRV Biofeedback, at HRV4Biofeedback.com HOW CAN I BENEFIT FROM BIOFEEDBACK? Life can be demanding, from both a physical and psychological point of view Our health and performance can be affected by how we are able to effectively cope with stressful situations and deal with anxiety, or in broader terms, our ability to emotionally self-regulate is key The goal of HRV Biofeedback is to improve self-regulation, therefore impacting positively our health and performance LEARN MORE: - App features: https://www.hrv4biofeedback.com/faq.html - An introduction to biofeedback: https://www.hrv4biofeedback.com/blog/a-primer-on-heart-rate-variability-biofeedback - How to use the camera measurement: https://www.hrv4biofeedback.com/blog/guidelines-and-best-practices-for-camera-based-measurements Supported devices for the camera measurement: iPhones 8 and onwards HRV4Biofeedback requires to register an account with your email address, so that your data can be backed up safely and retrieved in case anything happens (app issue, changing phone, etc.) The validation of the camera-based heart rate measurement is available here: https://www.researchgate.net/publication/315059917_Comparison_of_Heart_Rate_Variability_Recording_With_Smart_Phone_Photoplethysmographic_Polar_H7_Chest_Strap_and_Electrocardiogram_Methods
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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.