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
London Tube Map and Guide
Add a handy London Tube Map to your iPhone or iPad! A tube map is essential for any visit to London and this app contains the latest Tube Map courtesy of Wikimedia
$1.99 · In-app purchases
PRICE
$1.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.8
84 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 included17 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 London Tube Map and Guide: 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
Implement enhanced user guidance and tutorial features.
Assumption to check: Users often find the map hard to navigate and unintuitive.
Validate with people who use this workflow before building.
Hypothesis 2
Provide offline map access and saved routes.
Assumption to check: Limited offline functionality can frustrate users.
Validate with people who use this workflow before building.
Hypothesis 3
Optimize loading speeds and cache data effectively.
Assumption to check: Some users report performance issues with loading times.
Validate with people who use this workflow before building.
Hypothesis 4
Clearly outline subscription benefits and improve transparency.
Assumption to check: In-app purchases can be confusing or misleading.
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
Add a handy London Tube Map to your iPhone or iPad! A tube map is essential for any visit to London and this app contains the latest Tube Map courtesy of Wikimedia. It also has a route planner, nearest tube finder, live status and departure boards, plus a list of over 200 places of interest accessible by Tube. Summary of Features ------------------------------------- • London Tube Map provided by TfL • Route Planner • Quick access to departure info • Travel Zones displayed on map • Live status of Tube lines • Live departure information is available for selected stations • Complete browsable list of Tube stations • Find nearby stations on a local map • Points of Interest for over 200 places in London Selected App Store reviews: "Excellent App. Makes travelling in London a piece of cake!" "A great app and very reliable!" London Tube Guide works on iPhone, iPod touch and iPad. Please note: The route planner, tube map, station list and places list will all operate without an Internet connection. A GPS signal is required for the station finder feature. An internet connection is required for the live line status and departures information and for viewing websites.
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
Supabase
react-navigation
react-native-maps
react-native-vector-icons
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.
