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
Historical Markers
Thank you to everyone who wrote me about the recent bug that cause the app to crash when using location services in iOS 10
$1.99 · In-app purchases
PRICE
$1.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 3.5
32 ratings · Top 50%
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 included15 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 Historical Markers: map the core Reference 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
Enhance database integration to provide more comprehensive marker coverage.
Assumption to check: Limited content and markers available in certain regions
Validate with people who use this workflow before building.
Hypothesis 2
Implement better filtering and sorting options for markers.
Assumption to check: User interface can be cluttered with too many markers
Validate with people who use this workflow before building.
Hypothesis 3
Add offline caching for previously viewed markers.
Assumption to check: No offline access to marker information
Validate with people who use this workflow before building.
Hypothesis 4
Improve visibility of premium features and pricing in the app.
Assumption to check: In-app purchase options are not clearly communicated
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
Thank you to everyone who wrote me about the recent bug that cause the app to crash when using location services in iOS 10. Version 3.5 should solve this problem! Historical Markers displays the location and description of over 140,000 historic markers throughout North America. Access detailed plaque descriptions, photos, and links to online repositories of historical information. The app allows you to display markers near your current position or browse the entire marker catalog right on your device. Historical Markers contains thousands of markers with full plaque text from the Historical Marker Database (HMDB.org) as well as detailed place information for the entire U.S. National Registry of Historic Places. Historical Markers is a perfect application for anyone interested in learning about the history around them, whether on travel or closer to home. Features Include: - Over 71,000 markers from the Historical Marker Database - Over 76,000 markers from the U.S. National Registry of Historic Places - Images of markers and surrounding areas - GPS utility to display markers around your current location - Text to speech engine to allow voice dictation of marker descriptions while on the road - Area search for user specified address or city - Comprehensive search utility to sort through markers - Email marker information without leaving the app - The ability to create a custom list of favorite markers - Viewing history to help distinguish previously viewed markers - Share favorited markers via Facebook, Twitter, and other social media platforms - Offline database, allowing the app to work without an active data connection. - User selectable search radius (for improved performance on older devices) - Multithreading support for improved performance - Native iPad support Email us: [email protected] Become a fan: http://www.facebook.com/historicalmarkersapp Follow us: https://twitter.com/MarkersApp I've implemented the ability to favorite individual markers and a feature to help distinguish previously viewed markers, as suggested in the reviews. If you would like to share more suggestions on how to improve the app, or if you encounter a bug, please feel free to contact me at [email protected] or tweet ideas and/or comments to @MarkersApp. Also, please note that Historical Markers aggregates data from the Historical Marker Database and the U.S. National Registry of Historic Places. If a local marker is not in either of these databases, it will not appear in the app. If you would like to add a local marker to the Historical Marker Database, please visit http://www.hmdb.org. The ability to upload marker information and pictures directly from your iOS device is coming in a future release!
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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
Zustand
react-navigation
react-native-maps
expo-location
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.
