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
GrayZone - Light Meter
GrayZone reads light where you decide — not where
$2.99 · In-app purchases
PRICE
$2.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 2.3
3 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 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 GrayZone - Light Meter: map the core Photo & Video 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
Enhance with AI algorithms for improved accuracy.
Assumption to check: Limited measurement accuracy compared to professional tools.
Validate with people who use this workflow before building.
Hypothesis 2
Implement cloud storage for user data.
Assumption to check: Lack of cloud data backup.
Validate with people who use this workflow before building.
Hypothesis 3
Add a feature for users to share readings and tips.
Assumption to check: No user community or sharing options.
Validate with people who use this workflow before building.
Hypothesis 4
Include a tutorial or onboarding guide.
Assumption to check: Hard to use for beginners.
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
GrayZone reads light where you decide — not where your camera guesses. Built by Max of max&douglas — professional photographer with 25 years in editorial and advertising photography. Zone System Mode Measure a reference area first (Zone V), then check where the other tones will fall and their relative EV difference, for precise and consistent exposure. Real SPOT Metering Reads light exclusively in the area you select. Ideal for portraits, complex lighting and critical situations. Calibrated to render the selected area as neutral gray. Direct Exposure Control Set ISO before metering, like a dedicated light meter. Instant precise combinations of shutter speed and aperture. Exposure lock with AE LOCK. Half-stop support for finer control. MANUAL mode with over/underexposure scale. Essential Interface Live preview in your sensor's native ratio. NEW UI color inversion Shows only what you need. Nothing else. Complete Privacy No ads. No photos saved. No data collected or transmitted. For manual shooters — on film or digital. It does not replace your camera. It works alongside it.
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
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@react-native-reanimated
@supabase/supabase-js
BUILD KIT DIFFICULTY
Advanced
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.
