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
Pain Killer 2.0
Since the first iPhone and app store, Pain Killer 2.0 has been a favorite around the world
$4.99 · In-app purchases
PRICE
$4.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.8
140 ratings · Top 5%
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 Pain Killer 2.0: 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
Include HealthKit and Google Fit integration for better data tracking.
Assumption to check: Limited integration with health devices and platforms
Validate with people who use this workflow before building.
Hypothesis 2
Provide personalized exercise recommendations based on user pain history.
Assumption to check: Basic exercise suggestions
Validate with people who use this workflow before building.
Hypothesis 3
Offer a clearer explanation of subscription tiers and benefits.
Assumption to check: Subscription confusion
Validate with people who use this workflow before building.
Hypothesis 4
Add social features for users to connect and share experiences.
Assumption to check: Limited community features
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
Since the first iPhone and app store, Pain Killer 2.0 has been a favorite around the world. Pain Killer 2.0 gets rid of your pain, chronic pain, migraines and more...FAST. Put your headphones on and tap Start and YOUR PAIN MELTS AWAY IN MINUTES. It's that easy. HOW IT WORKS... Pain Killer 2.0 uses a very special, advanced binaural beats called TBSW. These special frequencies are ran through your headphones from Pain Killer 2.0 that safely release pain stopping endorphins, naturally and safely - all under YOUR control. WHY IT WORKS SO WELL... It works better than other pain relief methods, because the TBSW frequencies used in Pain Killer 2.0 are the latest and most effective available. POWERFUL PAIN RELIEF - NO ADDICTIONS - NO SIDE EFFECTS - SAFE & NATURAL Settings include : 1. General Pain 2. Muscle and Joint Pain 3. Headache Pain 4. TBSW Combo 5. Migraines 6. Rife Pain Set 7. Rife + TBSW 8. Regeneration 9. De-Stress 10. Pain + Insomnia 11. 528 Hz Also : * Has a fade at the session end, so you don't get jolted out of sleep, if you fall asleep * Can run in the background and in Auto lock mode - saving your battery or allowing you to do other things on your device * Easy to use interface with a countdown timer. * SUPER EASY TO USE! There's also Help built-in to the app, so everything you need is right at your fingertips. If you have pain - Pain Killer 2.0 will quickly become your #1 app, like it has for so many others over the years. GET IT NOW, because there is NO need to be in pain any more...
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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.
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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.
