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
Happy: Codex & Claude Code App
Happy Coder is the secure mobile companion for Codex and Claude Code that lets you continue your AI coding sessions anywhere (not affiliated with Anthropic or OpenAI)
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.9
1,012 ratings · Top 5%
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 included16 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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Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Happy: Codex & Claude Code App: map the core Developer Tools 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
Implement a robust code execution environment supporting multiple languages.
Assumption to check: Limited code execution features compared to desktop IDEs
Validate with people who use this workflow before building.
Hypothesis 2
Add real-time collaboration tools for users to work together.
Assumption to check: Lack of collaborative features for sharing code
Validate with people who use this workflow before building.
Hypothesis 3
Introduce folders or tagging system for better organization of code.
Assumption to check: Difficulty in managing large code snippets
Validate with people who use this workflow before building.
Hypothesis 4
Optimize the app for performance on a wider range of devices.
Assumption to check: Inconsistent performance on older devices
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
Happy Coder is the secure mobile companion for Codex and Claude Code that lets you continue your AI coding sessions anywhere (not affiliated with Anthropic or OpenAI). Built by developers who needed to check on their AI assistant's progress during coffee breaks, this app brings the full Codex and Claude Code experience to your phone with military-grade encryption. **Important**: This app requires Codex or Claude Code to be installed on your computer. Happy Coder is a companion app that connects to your existing Codex or Claude Code setup. **Key Features:** - Continue Codex and Claude Code sessions seamlessly between desktop and mobile - Push notifications for permission requests and task completion - Access conversation history even when your terminal is offline - End-to-end encryption - your code stays private - Real-time streaming of AI responses - Zero-knowledge architecture - we can't read your data **How It Works:** 1. Install the happy-coder CLI on your computer 2. Scan a QR code to securely pair your devices 3. Use 'happy' instead of 'codex' or 'claude' to start encrypted sessions 4. Switch between desktop and mobile instantly Perfect for developers who: - Want to monitor long-running tasks on the go - Need secure access to proprietary code discussions - Value privacy and open-source transparency - Work from coffee shops, trains, or anywhere Happy Coder uses the same encryption as Signal (TweetNaCl) and is completely open source. Your encryption keys never leave your device, and all data is encrypted before transmission. Built by Bay Area engineers who believe the best tools come from scratching your own itch. We needed a way to securely check on our AI coding assistant while away from our desks - so we built it and shared it with the community. Your code. Your privacy. Your Codex and Claude Code companion. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
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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
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axios
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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.
