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
eCalendar - Daily Planner
【Automatic renewal of eCalendar membership】
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.6
10,397 ratings · Top 15%
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 should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
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/
Preview a sample Build Kit No email needed
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 eCalendar - Daily Planner: map the core Photo & Video 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 colors, add reminders, and set recurring events.
Assumption to check: Limited customization options for events and tasks
Validate with people who use this workflow before building.
Hypothesis 2
Simplify UI by categorizing features and providing a cleaner design.
Assumption to check: Cluttered user interface with too many features
Validate with people who use this workflow before building.
Hypothesis 3
Optimize photo loading and caching for faster performance.
Assumption to check: Performance issues when loading photos
Validate with people who use this workflow before building.
Hypothesis 4
Add integrations with Google Calendar and Apple Calendar for better synchronization.
Assumption to check: Lack of integrations with external calendars
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
【Automatic renewal of eCalendar membership】 eCalendar membership benefits: Magic import: add today's reminder via email. Subscription period: 1 month (eCalendar monthly automatic renewal plan) 12 months (eCalendar annual automatic renewal plan) Subscription price: based on iAP application information. For example, the monthly automatic renewal plan is $2.99 per month, and the annual automatic renewal plan is $29.90 per year. Payment: After the user confirms the purchase, the payment will be remitted to his iTunes account. Cancel automatic renewal: To cancel automatic renewal, please manually turn off the automatic renewal function in iTunes/Apple ID settings at least 24 hours before the current subscription period. Renewal: Within the first 24 hours of the subscription, your Apple iTunes account will be deducted, and the subscription will be extended for an additional subscription period after the payment is successful. Price: https://agreement-calendar.myecalendar.com/#/pages/policy/index?language=EN Automatic renewal service agreement: https://agreement-calendar.myecalendar.com/#/pages/automatic-renewal/index?language=EN Membership service agreement: https://agreement-calendar.myecalendar.com/#/pages/member/index?language=EN This application needs to access your location information and use this information to select the city weather corresponding to your personal location To use this application to upload photos and avatars, you need to access your photo album Terms of Service: This application is subject to Apple's standard terms of service (EULA), please refer to: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
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
React Navigation
Axios
React Native Async Storage
Expo Image Picker
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.
