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
Baseball Pitch Speed - Radar Gun
***How FAST can you throw?!?***
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 2.3
15 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.
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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 included17 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 Baseball Pitch Speed - Radar Gun: 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 features like pitch tracking, analytics, and sharing.
Assumption to check: Limited functionality beyond pitch speed measurement
Validate with people who use this workflow before building.
Hypothesis 2
Implement a modern and engaging UI design.
Assumption to check: User interface is not visually appealing
Validate with people who use this workflow before building.
Hypothesis 3
Simplify and clarify in-app purchase options.
Assumption to check: In-app purchase process is not well integrated
Validate with people who use this workflow before building.
Hypothesis 4
Conduct user feedback sessions to identify pain points and improve the app.
Assumption to check: Low user ratings indicate dissatisfaction
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
***How FAST can you throw?!?*** Baseball Pitch Speed is the best tool for any pitcher to find their pitch speed and track their pitch count. ***Are you a FIREBALL thrower?*** This app uses an advanced color changing user interface that reflects the speed of your pitches. Pitch Speed Color Chart: 0-40 ► Chilly Blue ► (Slow) 41-50 ► Cool Green ► (Average) 51-60 ► Mello Yellow ► (Pretty Fast) 61-75 ► Heating up Orange ► (Really Fast) 76+ ► Fireball Red ► (Wow Fast!) So how does it work? This pitch speed calculator is very easy to use and only includes 2 steps: 1. √ Press start when pitcher pitches the ball 2. √ Press stop when catcher catches the ball. ***FEATURES*** ►Baseball Pitch Speed is a 3 in 1 essential baseball tool. Find pitch/throwing speed. Keep pitch count Stopwatch for drills ►Uses advanced calculation to find an accurate pitch speed. Displays speed history for 4 pitches ►Color based pitching speed ranking system. Blue,Green,Yellow,Orange,Red ►Custom distance for any league. ►Presets for 3 leagues. Majors Baseball Little League Fastpitch Softball ►Much cheaper than traditional radar gun. ►Can be used for any sport or activity Baseball/Softball pitch/throw speed. Baseball drills (speed around the bases). Hockey shot speed. Soccer kick speed. ***BONUS*** Great entertainment at the ballpark to see who can get closer to the actual scoreboard speed.
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
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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.
