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
WatchCal for Google Calendar
WatchCal is a beautiful Calendar for your Apple Watch and iPhone
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 1.4
9 ratings · Below Average
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.
Build your own version
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/
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 WatchCal for Google Calendar: map the core Productivity 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
Focus on adding unique features like natural language event creation.
Assumption to check: Limited features compared to other calendar apps.
Validate with people who use this workflow before building.
Hypothesis 2
Design a clearer and more intuitive interface.
Assumption to check: Poor user reviews indicate a confusing UI.
Validate with people who use this workflow before building.
Hypothesis 3
Ensure reliable synchronization and provide feedback on sync status.
Assumption to check: Sync issues reported with Google Calendar.
Validate with people who use this workflow before building.
Hypothesis 4
Allow users to customize event colors, reminders, and layouts.
Assumption to check: Lack of customization options for events.
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
WatchCal is a beautiful Calendar for your Apple Watch and iPhone. With full support for Google Calendar, you can always stay on top of your events and schedule - where ever you go. Features: - Full Google Calendar Support - Apple Watch Support - Create and Quick Add Events - Easily Delete Events - Search across all calendars - unified search - Set Primary Calendar to open the app exactly where you want it. - Edit existing events - Manage multiple calendars with simple drop down menu - Month view to plan ahead and see your availability Note that you must have a Google account to sign in and access your calendar. Privacy: We NEVER save, share, or otherwise distribute any of your data or information. All communication regarding your calendar is secured from your device to Google Calendar. We do not use any of our servers for storage. Google Account & Security: We abide by Google Calendar policies. Users must have log in and grant access to their Google Calendar to use the app. Feedback: We always love hearing from you. Don't hesitate to reach out with any feedback, suggestions, or concerns. We, together, will make the best Watch first Calendar experience! ~ Happy Calendaring ~
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
Supabase
React Navigation
Zustand
date-fns
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.
