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.
The app enables navigation with the sun and is comparable to satellite navigation on a chart plotter
$8.99 · In-app purchases
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.
A product spec, screen plans, and build steps for your coding agent.
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Combine features and design from your favorite apps.
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What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
A product spec, phased build plan, differentiation notes, and screen references.
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Goal: Send a clear invoice after finishing a job.
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.
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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Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
Rork plan preview for Circle Of Position Navigation: map the core Navigation workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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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
Assumption to check: Limited user feedback and engagement
Validate with people who use this workflow before building.
Hypothesis 2
Assumption to check: Poor map functionality
Validate with people who use this workflow before building.
Hypothesis 3
Assumption to check: Confusing user interface layout
Validate with people who use this workflow before building.
Hypothesis 4
Assumption to check: High price point for limited features
Validate with people who use this workflow before building.
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
The app enables navigation with the sun and is comparable to satellite navigation on a chart plotter. A sextant is needed because, unlike satellites, the sun does not emit radio signals. The distance to an observer must therefore be measured manually with a sextant from the earth. For a position determination only the times and the sextant readings of two observations to be entered. The position is immediately displayed as a ship symbol on an electronic map. A track of the journey is displayed based on the positions determined and the data from an integrated dead reckoning module. So, the app can be used by anyone without any knowledge of celestial navigation. The sun cannot be confused with any other star and is available all day. Navigating with stars requires specialist knowledge so that stars can be reliably identified. At night the height of stars cannot be measured because the horizon is not visible. With this app it is now possible to have a real second independent navigation system on board that anyone can use immediately, even in stressful situations and without prior instruction. Celestial navigation is a demonstrably a valid and safe navigation method. Sailors should always be able to master and use classic celestial navigation. A failure of satellite navigation is difficult to imagine, but not impossible. A lot of money is spent each year on buying and maintaining yacht safety equipment in case of rare incidents that normally do not happen, but very little is done or available in the event of satellite navigation failure. This app makes it very easy to meet the requirements for navigational safety of the ship and crew. It is professional system and makes it possible to check the functionality of the on board satellite navigation electronics with a totally independent system. For some sailors, classic celestial navigation is even a passion, finding the way only with the help of the heavens. After all, sailing itself is a historical form of travel. The app based on the ideas of the renowned German mathematician Carl Friedrich Gauss in 1809. His solution was way ahead of its time. A position is calculated from the heights of two celestial bodies, or the sun at two different times and entered on a nautical chart. Satellite navigation works similar way. Since there were no computers at that time sailors invented graphical approximation methods and only these methods are in use to this day. They are extremely complex and time-consuming and require a high level of knowledge of mathematics. In our modern times this greatly reduces the general appeal of celestial navigation as a backup system for safety at sea. Compared to the commonly known graphical Marcq St. Hilaire method this app offers considerable advantages: 1. 1.There are no errors when measuring heights above 70 degrees. 2. 2.The time between two observations of the sun can be much shorter. 3. 3.To calculate a position, no DR-Position is necessary. 4. 4.The calculation algorithm is precise and is not an approximation. The app includes the following functions: 1. 1.Automatically altitude corrections of sextant readings. 2. 2.An additional use of the noon latitude is possible. 3. 3.Module for dead reckoning with track recording. 4. 4.Map-download-function. 5. 5.Zoom function from the whole Earth down to the yacht harbor. 6. 6.Distance measurement from the ship's position to a destination. 7. 7.Representation of circles of position on the globe. 8. 8.Navigation simulator beside to an ongoing navigation. 9. 9.Sun almanac until 31. December 2040 in a data base. 10. 10.Detailed description in a help file. Never before has it been so easy to navigate with the sun. No mathematics, no drawing and no searching in complicated tables. With this app celestial navigation becomes fun instead of arduous. Even if the accuracy of astronavigation takes getting used to at first, with this app and a cheap plastic sextant you are safer on the sea.
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Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
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.