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
PACE: Habit Tracker
#1 Paid Productivity App in Japan (Feb 2026).
$2.99 · In-app purchases
PRICE
$2.99
In-app purchases
BUSINESS MODEL
Paid
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 included16 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 PACE: Habit Tracker: 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
Incorporate gamification elements like rewards for completing streaks.
Assumption to check: Users often find it hard to maintain motivation in habit tracking apps.
Validate with people who use this workflow before building.
Hypothesis 2
Provide simple, intuitive reminder setup with pre-set options.
Assumption to check: Many users report difficulty in setting reminders.
Validate with people who use this workflow before building.
Hypothesis 3
Implement a dashboard view that summarizes progress at a glance.
Assumption to check: Tracking multiple habits can be overwhelming.
Validate with people who use this workflow before building.
Hypothesis 4
Clearer explanations of benefits for each subscription tier and simplified paywall process.
Assumption to check: In-app purchase confusion regarding subscription tiers.
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
#1 Paid Productivity App in Japan (Feb 2026). You want to keep moving, but some days it's hard to know what "enough for today" looks like. PACE shows what's left, how many days remain, and your current pace together — so your next step becomes clear without overthinking. No account. No cloud. Your data stays on-device. Create a goal (count + deadline), then tap + when you make progress. PACE updates everything together and shows your pace status: Fast, Ahead, On pace, Slow, or Behind. 5 levels from ahead to behind help you understand where you are: - Fast: Well ahead of target pace. You can ease up. - Ahead: Slightly ahead. Keep it comfortable. - On pace: Best range. This is your target pace. - Slow: Slightly behind. A small push helps. - Behind: Behind pace. Catch up in small steps. Key features: - Home Screen widgets (small, medium, large) — check pace and log progress without opening the app - Goal setup (deadline, target count, unit) - Quick + logging from Home/Detail - Edit and delete history (date and note) - Weekly / monthly / yearly recurring goals - CSV export - Clear completed / missed result - Japanese / English and Light / Dark support Great for: - Reading & study (e.g. Read 100 books this year) - Fitness & habits (e.g. Run 20 times this month) - Work & preparation (e.g. 200 problems before the exam) No sign-up needed. No tracking. Your data stays on your device. PACE is built to help you continue with ease and still stay on track.
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
react-native-reanimated
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.
