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
StopWatch For Swimming
The professional swim timing app built for coaches and athletes
$1.99 · In-app purchases
PRICE
$1.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.5
16 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 included18 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 StopWatch For Swimming: map the core Sports 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
Add historical data graphs and progress tracking
Assumption to check: Limited functionality for tracking performance over time
Validate with people who use this workflow before building.
Hypothesis 2
Allow users to customize lap lengths and alerts
Assumption to check: No customization options for lap settings
Validate with people who use this workflow before building.
Hypothesis 3
Introduce additional premium features for training analysis
Assumption to check: In-app purchases feel limited
Validate with people who use this workflow before building.
Hypothesis 4
Implement a cleaner, streamlined UI for ease of use
Assumption to check: User interface can feel cluttered with too many options
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
The professional swim timing app built for coaches and athletes. Time individual swimmers, group sessions, and relay teams — all from your iPhone. INDIVIDUAL TIMER Time a single swimmer with automatic lap splits, cumulative totals, and estimated finish times updated in real time. INDIVIDUAL+ TIMER Time an entire heat at once. Each swimmer gets their own splits, lap distances, and estimated finish — all running simultaneously. RELAY TIMER Time all four legs of a relay with automatic handoff detection. See each leg's split and total time the moment the swimmer touches the wall. SESSION REPORTS Every session is saved automatically. Review splits, share results as an image, and compare performances over time. BUILT FOR THE POOL -SCY, SCM, and LCM course support -1-length and 2-length lap options -All data stored locally — no account required -No ads, no tracking
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
Firebase
react-native-async-storage
react-navigation
zustand
BUILD KIT DIFFICULTY
Starter
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.
