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
Jinshu Reader
Stop looking up words
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
N/A
No ratings yet
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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Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Jinshu Reader: 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
Implement a robust search and categorization system.
Assumption to check: Users struggle to find relevant content quickly.
Validate with people who use this workflow before building.
Hypothesis 2
Add gamification elements like badges and leaderboards.
Assumption to check: Limited interactive features for engagement.
Validate with people who use this workflow before building.
Hypothesis 3
Enhance tracking with detailed analytics and user feedback.
Assumption to check: Inadequate progress tracking functionality.
Validate with people who use this workflow before building.
Hypothesis 4
Allow users to download articles for offline reading.
Assumption to check: No offline access to reading materials.
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
Stop looking up words. Start reading. Every English learner knows the pain: you open an English book, hit an unknown word on the first page, switch to your dictionary app, look it up, switch back, lose your place, and repeat. By page three, you've given up. Jinshu eliminates this cycle entirely. Import any English book and every vocabulary word is automatically annotated with translations in Chinese, Korean, or Japanese — right where you need them, right as you read. SMART VOCABULARY ANNOTATIONS - Words annotated automatically from a ~30,000-word dictionary with CEFR levels (A1-C2) - Choose your display: ruby text above words, inline parentheses, or tap-to-reveal - Set your proficiency level — only see annotations for words you're still learning - IPA pronunciation for every annotated word - Translations in 中文, 한국어, and 日本語 TAP ANY WORD TO LEARN IT - First tap: hear the word pronounced aloud - Second tap: see IPA, translation, CEFR level, and full details - One tap to save any word to your vocabulary book with its sentence context - Saved words become spaced-repetition flashcards — review at scientifically optimal intervals - FSRS algorithm (used by Anki) schedules reviews so words stick in long-term memory LISTEN TO BOOKS READ ALOUD - Neural TTS (Kokoro: 82M-parameter AI) — natural, human-like voices running on-device - 8 voice options: Heart, Bella, Sarah, Nova, Adam, Michael, Emma, Daniel - Sentence-by-sentence highlighting as you listen - Adjustable speed (0.5x-2.0x), sleep timer, background playback - Lock screen controls and chapter auto-advance - Works completely offline — no streaming, no internet needed A READER YOU'LL ACTUALLY ENJOY - 5 reading themes: Light, Sepia, Dark, Calm, Slate - Premium typography: Charter, New York, Palatino, Athelas, Iowan Old Style - Upload your own .ttf/.otf fonts for a fully personalized experience - Adjustable font size, line spacing, margins, text alignment, paragraph indent, bold text - All settings apply instantly — no page reload YOUR LIBRARY, YOUR WAY - Import EPUB, PDF, Markdown files, or paste any web URL - Organize books into collections - Search by title or author - Track reading streaks and daily reading time - 5 classic books included free: The Great Gatsby, The Hound of the Baskervilles, Walden, Crime and Punishment, Ashenden - Duplicate detection prevents re-importing the same book HIGHLIGHTS, NOTES & BOOKMARKS - Highlight text in 3 colors (yellow, blue, pink) - Add notes to any highlight - Share highlights as beautiful quote cards (3 visual styles) - Bookmark pages, search within chapters SYNC & TRANSFER - iCloud sync — reading progress, bookmarks, highlights, vocabulary across all your devices - LAN Transfer — send books and all data between devices over Wi-Fi, no cloud needed - No account required to start. Sign in with Apple when you're ready. PRIVACY FIRST - No account required - No ads, ever - No tracking, no analytics - Fully offline — dictionary, annotations, TTS, SRS review - Your books and data stay on your device (or your iCloud) FREE VS PREMIUM Free: 8 EPUB imports, A1-A2 annotations, 50 saved words, 2 themes, system TTS Premium: Unlimited imports (EPUB/PDF/MD/URL), all CEFR levels, unlimited vocabulary, 5 themes, neural TTS, custom fonts, iCloud sync, LAN transfer Plans: Monthly / Yearly / Lifetime Terms of Use: https://jinshu.built4.fun/terms Privacy Policy: https://jinshu.built4.fun/privacy
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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
Supabase
react-native-animated
react-native-svg
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.
