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
Trip fuel cost calculator
A handy calculator to estimate the fuel consumption and fuel cost of a trip.
$3.99 · In-app purchases
PRICE
$3.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.0
1 ratings · Top 30%
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 included14 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 Trip fuel cost calculator: map the core Travel 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
Allow users to define custom fuel efficiency units or categories.
Assumption to check: Limited customization options for fuel efficiency input
Validate with people who use this workflow before building.
Hypothesis 2
Provide a detailed cost breakdown by fuel type and distance.
Assumption to check: No detailed breakdown of costs
Validate with people who use this workflow before building.
Hypothesis 3
Incorporate a map interface for users to plan trips based on their routes.
Assumption to check: Lack of integration with maps for trip planning
Validate with people who use this workflow before building.
Hypothesis 4
Enable sharing of trip calculations on social media.
Assumption to check: No social sharing features
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
A handy calculator to estimate the fuel consumption and fuel cost of a trip. The fuel cost calculator can help you figure out how much fuel you need for your trip and how much it will cost. Enter the distance (in miles or kilometers), the average fuel consumption for your vehicle (in MPG US, MPG UK, km/L or L/100 km) and the price of fuel and the calculator will show you how much fuel your vehicle is predicted to consume (Fuel Total) and how much a trip will cost (Total Cost). In case of using toll roads you can add tolls for your trip, use 'plus' sign to calculate multiple tolls and get the total amount. You can optionally add the number of passengers and the calculator will calculate you the cost of your trip per passenger. The app does calculations in imperial (MPG US or MPG UK) and metric (km/L or L/100 km)) units. You can round results to the specified number of decimal places. By default, the app displays 2 decimal places. To round results to the nearest whole number, select 0 decimal places. The fuel calculator keeps calculation history so you can easily view and compare your recent calculations. Sends results and history via email.
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
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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.
