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
EP QTc
This app collects over 30 published formulas for calculating the corrected and predicted QT interval (QTc and QTp)
$0.99
PRICE
$0.99
No in-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 5.0
1 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.
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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/
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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 EP QTc: map the core Medical workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
Screenshots
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App Store description
This app collects over 30 published formulas for calculating the corrected and predicted QT interval (QTc and QTp). Included are details on each formula and reference links. Results are analyzed statistically and graphed. Published definitions of normal and abnormal QTc intervals are also included. This is no ordinary calculator that just gives you the results of Bazett's formula. If you are interested in this fascinating corner of electrocardiology, this app is for you.
Written user reviews are not shown here. Check current App Store reviews >
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 more calculation methods to increase usability.
Assumption to check: Limited calculation methods for QTc
Validate with people who use this workflow before building.
Hypothesis 2
Include educational content on QTc and its implications.
Assumption to check: No detailed explanations for results
Validate with people who use this workflow before building.
Hypothesis 3
Allow users to save preferences or frequently used calculations.
Assumption to check: Lack of user customization options
Validate with people who use this workflow before building.
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
React Native Paper
TypeScript
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.
