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
Start Running: Couch to 5K
Transform from couch potato to 5K runner with C25K — the free interval training app that respects your time and your workout.
$1.99 · In-app purchases
PRICE
$1.99
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 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 Start Running: Couch to 5K: map the core Health & Fitness 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 their training plans based on personal preferences.
Assumption to check: Many users find Couch to 5K apps too rigid and not customizable enough.
Validate with people who use this workflow before building.
Hypothesis 2
Incorporate social features for users to connect and share progress.
Assumption to check: Users often report a lack of community features.
Validate with people who use this workflow before building.
Hypothesis 3
Enhance audio feedback with personalized coaching options.
Assumption to check: Some users feel the audio cues are not clear or motivational.
Validate with people who use this workflow before building.
Hypothesis 4
Implement an interactive onboarding experience to guide new users.
Assumption to check: Apps can be overwhelming for beginners without proper onboarding.
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
Transform from couch potato to 5K runner with C25K — the free interval training app that respects your time and your workout. NO ADS. EVER. We believe your workout should be distraction-free. No banner ads. No video ads. No "watch an ad to continue." Just you and your run. HOW IT WORKS C25K uses proven interval training to gradually build your running endurance. You'll alternate between running and walking, with each workout getting slightly more challenging. Before you know it, you'll be running 5K continuously. CHOOSE YOUR PROGRAM • 8-Week Classic — The original C25K program for motivated beginners • 10-Week Gradual — More time to build endurance at each level • 12-Week Easy — The most gradual progression, perfect for true beginners FEATURES • Audio cues tell you exactly when to run and walk • See your workout on the Lock Screen with Live Activities • Track your progress and build streaks • Works offline — no internet required • Dark mode interface that's easy on your eyes YOUR TYPICAL WORKOUT Each session includes a 5-minute warmup, your interval training, and a 5-minute cooldown. Workouts range from 20-35 minutes, 3 days per week. WEEK 1 EXAMPLE Alternate 60 seconds of running with 90 seconds of walking, repeated 8 times. Simple, achievable, and the start of something great. PRIVACY FIRST Your data stays on your device. We don't collect analytics, don't track you, and don't sell anything. Your running journey is yours alone. Start today. Your future self will thank you.
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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
Redux
react-native-svg
react-navigation
Firebase
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.
