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
eRokuyo
eRokuyo presents a Japanese traditional calendar.
$0.99 · In-app purchases
PRICE
$0.99
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 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 eRokuyo: map the core Lifestyle 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
Allow users to customize task colors, categories, and reminder types.
Assumption to check: Users find the app lacks customization options for tasks and events.
Validate with people who use this workflow before building.
Hypothesis 2
Optimize performance and test for stability in calendar rendering.
Assumption to check: Some users experience crashes during the calendar view.
Validate with people who use this workflow before building.
Hypothesis 3
Implement functionality for users to set up recurring tasks/events.
Assumption to check: Limited support for recurring tasks or events.
Validate with people who use this workflow before building.
Hypothesis 4
Enable syncing with popular calendar apps like Google Calendar or Apple Calendar.
Assumption to check: Users want better integration with other calendar apps.
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
eRokuyo presents a Japanese traditional calendar. It support until 2030. when it was already purchased ePrint, you can print the calendar from ePrint. When is taian or butsumetsu to decide marriage or engagement? What day is good to get a new car or a house? What day is good to move? When is the National Holiday? When is the consecutive holidays or National Holidays at the next year? When is the next full moon? When is the dog day? What will be the condition of the sea for fishing? When is the Tensha-nichi for start new job? When is Ichiryumambaibi or Sanpuku for seed? When is Daitsuchi or Shotsuchi to cut down trees? eRokuyo is useful for your important scene. [Display contents] - Year/ Month/ Day - a day of week - the National Holiday - the old calendar - the Rokuyo (taian, shakko, sensho, tomobiki, senpu and butsumetsu) - the Kyusei (ippaku, jikoku, sanpeki, shiroku, gou, roppaku, shichiseki, happaku and kyushi) - the 12 earthly branches (rat, ox, tiger, rabbit, dragon, snake, horse, ram, monkey, cockerel, dog and pig) - the 10 heavenly stems (kinoe, kinoto, hinoe, hinoto, tsuchinoe, tsuchinoto, kanoe, kanoto, mizunoe, mizunoto) - the Solar term (Risshun, Usui, Keichitsu, Shumbun, Seimei, Kou, Rikka, Boshu, Geshi, Shousho, Taisho, Risshu and so on.) - the 5 seasonal festivals (Nanakusa, Hinamatsuri, Tango-no-sekku, Tanabata and Choyou-no-sekku) - other seasonal festivals or events (Setsubun, Valentine's Day, Hachijuhachiya, Higan, Mother's Day, Shanichi, Rojitsu, International Labour Day, Shichi-Go-San and so on.) - day character (Hassen, Jippogure, Tenchitenjo, Hantsuchi, Sanpuku, Sanrinbo, Fujojubi, Tensha-nichi and Ichiryumambaibi) - waxing and waning of the moon (the age of the moon, a full-moon, a new moon, a half moon) - ebb and flow (Oshio, Nakashio, Koshio, Nagashio and Wakashio) - sunrise or sunset (Tokyo) [Functions] - Display monthly calendar. - Display detailed daily information. - Jump to specified year or month. - Jump to today. - Show/Hide the 12 earthly branches (Eto). - Show/Hide the old calendar (Old). - 10 background colors. (Monthly calendar) - Set specified stamp each day. (30 icons) - Save the monthly calendar image to your Photo Albums. (day/rokuyo/moon/stamp only) - Display version information. [Operations] - Monthly calendar Tap the number of the month to display picker, and you can easily to change the year or month. - Daily information Tap the daily information, you can easily to change daily information detailed or simple. - Tool bar Tap the Save button to save the monthly calendar image to your Photo Albums. Tap the Color button to change calendar background color. (10 colors) Produced by e-Workshop
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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
Supabase
React Navigation
Date-fns
React Native Paper
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.
