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
Reciprocity Plus
Reciprocity+ : photo tool, for calculating long exposure, for digital and analog photography
$1.99 · In-app purchases
PRICE
$1.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.1
7 ratings · Top 30%
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 Reciprocity Plus: 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
Offer more diverse and customizable filters.
Assumption to check: Limited filter options compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Integrate cloud storage for saving user edits.
Assumption to check: No cloud backup for edits
Validate with people who use this workflow before building.
Hypothesis 3
Implement guided tutorials for new users.
Assumption to check: Lack of user-friendly tutorials
Validate with people who use this workflow before building.
Hypothesis 4
Optimize image processing for smoother performance.
Assumption to check: Occasional performance lags during editing
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
Reciprocity+ : photo tool, for calculating long exposure, for digital and analog photography. Are you tired of mentally multiplying exposure time with yor ND3+ND8 filters, and then adding reciprocity failure rate ? Reciprocity + is for you : • 29 Filters : CTO, CTB, Green series, ND serie and more • 110 Reciprocity charts included. • Design your own chart or modify an existing one • Share your charts with PInhole Assit App, • Share by email •Available charts : • A chart adapted from Jim Shull's The Hole Thing • Two charts for RC photo paper , • 400TX,TMX,TMY,HP5+,100 Delta (source APUG forums) • max 400, T max 100,TRiX & Plus 125, Ilford films (Without Lenses website ) • Official Ilford films. • Ektachrome, Fujichrome, Agfachrome and + from "Using the View Camera". • Arista films (courtesy of David Aimone) • Ilford Pan F, Fuji FP100, Fuji Neopan 100 ACROS, Ektar 100 • Fuji FP 3000B • and more (119 films). • A timer, of You can quit the app, no matter what you do, the timer will notify you when the exposure is over. From the makers of Pinhole Assist.
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
Supabase
React Navigation
Zustand
react-native-reanimated
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.
