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
R.D. Murray Train Signals App
As a Conductor, Locomotive Engineer, Signal Person or other signal related professional in the railroad industry it's important to always be able to recognize the many railroad signals and signs
$19.99 · In-app purchases
PRICE
$19.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.8
6 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 included13 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 R.D. Murray Train Signals App: map the core Education 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 gamification elements like quizzes and rewards.
Assumption to check: Limited interactivity in educational apps can lead to disengagement.
Validate with people who use this workflow before building.
Hypothesis 2
Regularly update signal information and add new signals.
Assumption to check: Content can become outdated quickly.
Validate with people who use this workflow before building.
Hypothesis 3
Implement a progress tracking system with achievements.
Assumption to check: User retention can be a challenge due to lack of motivation.
Validate with people who use this workflow before building.
Hypothesis 4
Offer a free trial or tiered pricing model to attract more users.
Assumption to check: High price point may discourage users.
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
As a Conductor, Locomotive Engineer, Signal Person or other signal related professional in the railroad industry it's important to always be able to recognize the many railroad signals and signs. This app will help you do just that. It contains the standard NORAC signals and signs as digital flashcards allowing you to study anywhere at your own pace. The R.D. Murray Signals App is not just a digital deck of flashcards, it's also a testing system that allows you to improve you signal recognition ability by giving you a variety of ways to test your skill including a timed test. You can even post your score on a leaderboard and compete with your friends. There's also a section on important NORAC operating rules which we update periodically. With signals, signs and rules all accessible right from your smartphone, you'll always be on top of your game anytime and anywhere. This app is constantly being updated. We're working on adding leaderboards, better graphics for signs and other cool features soon. Please let us know what new features you'd like to have in the R.D. Murray Signals App
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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
React Native Sound
TypeScript
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.
