App Overview

Four Days icon

Four Days

Sergio Gutierrez Mota · Health & Fitness

If you have multiple food allergies, one of the best ways to help yourself is to “rotate” your foods, or eat a rotation diet

$1.99 · In-app purchases

PRICE
$1.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
2.6
8 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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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.

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.

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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Rork plan preview for Four Days: 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

Add more types of activities and detailed analytics.

Assumption to check: Limited features for activity tracking compared to competitors

Validate with people who use this workflow before building.

Hypothesis 2

Focus on stability and performance improvements.

Assumption to check: Poor user ratings due to bugs and crashes

Validate with people who use this workflow before building.

Hypothesis 3

Introduce social challenges and community features.

Assumption to check: Lack of social features for motivation

Validate with people who use this workflow before building.

Hypothesis 4

Reassess the timing of the paywall and offer more free features initially.

Assumption to check: Paywall appears too early

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

If you have multiple food allergies, one of the best ways to help yourself is to “rotate” your foods, or eat a rotation diet. Four days allow you to keep track of what you are eating to avoid repetition and prevent you from forming new food intolerances What is a rotation diet? A rotation diet is a system of controlling food allergies by eating biologically related foods on the same day and then waiting at least four days before eating them again. Such a diet can help those with food allergies in several ways and may help prevent the development of allergies to new foods. Why rotate your foods? 1. We are biologically designed to rotate foods. Man is meant to eat with the seasons. We are not designed to eat avocado every single day, because nature does not allow for it. In nature (or even 100-150 years ago) we ate what was local and available. 2. Rotation allows for more nutrient diversity. If we eat avocado as our main source of fat every day, we’re missing out on all of the healthy fats in olive oil, coconut, and beef tallow. Different foods come with different nutrients and we need variety for vibrancy! 3. Eating the same foods constantly can cause food intolerances and impede gut healing Any food, if eaten repetitively, can cause food allergies especially if we have gut issues. Why? Like we stated above, our bodies aren’t designed to eat the same thing over and over again. And if we have permeable intestines and are eating avocado daily, our immune system is reacting to the avocado over, and over, and over again. Eventually it becomes too much. Surely, the goal is to heal the gut. However, an important piece of gut healing is to remove inflammation, and stopping new intolerances from forming. Thus, a rotation diet can be an amazing strategy within a gut healing template.

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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.

SUGGESTED BUILD STACK
React Native
Expo
Axios
React Navigation
Redux
Firebase
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.