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
CrossPort
CrossPort is the companion iOS app for e-ink readers running CrossPoint, an open-source third-party firmware for Xteink X4, X3, and compatible devices
$2.99 · In-app purchases
PRICE
$2.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 5.0
2 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 included18 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 CrossPort: map the core Books 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 personalized recommendations based on user reading habits.
Assumption to check: Limited discovery features for new books
Validate with people who use this workflow before building.
Hypothesis 2
Add a feature for users to share their progress and book reviews.
Assumption to check: Lack of social features
Validate with people who use this workflow before building.
Hypothesis 3
Enable offline access to books and reading progress.
Assumption to check: Poor offline functionality
Validate with people who use this workflow before building.
Hypothesis 4
Provide more advanced filtering and sorting options in the library.
Assumption to check: Inadequate filtering options
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
CrossPort is the companion iOS app for e-ink readers running CrossPoint, an open-source third-party firmware for Xteink X4, X3, and compatible devices. Also works with alternative firmwares based on CrossPoint. Manage your books, wallpapers, and files — all over WiFi. LIBRARY & READING • Browse your full book library with cover art from Open Library, Apple Books, and Google Books • Track reading progress synced bidirectionally with your device • Built-in EPUB reader for reading on your phone with automatic progress sync back to the device • Download books to read on the go, upload from your phone to the device WALLPAPER • Add custom sleep screen wallpapers from your photos or files • Preview how wallpapers look on your device with a realistic e-ink display simulation • Send wallpapers to your device with one tap FILE MANAGEMENT • Browse, upload, rename, move, and delete files on your device • Upload progress tracking for large files • Automatic EPUB optimization with image compression • Smart filename cleanup for archive downloads SMART FEATURES • Automatic device discovery on your local network • Book cover art from multiple sources with EPUB fallback • XTC/XTCH file upload and management • Home screen widget showing your current read • Deep link support for quick access from widgets Requires a device running CrossPoint or a compatible firmware with WiFi file transfer mode enabled. Works with the Xteink X4, X3, and other supported devices.
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
Axios
AsyncStorage
React Navigation
TypeScript
BUILD KIT DIFFICULTY
Advanced
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.
