🎸 FretFlow

Master the guitar fretboard with science-backed spaced repetition

What is FretFlow?

Learning guitar means memorizing hundreds of note positions across the fretboard. FretFlow makes this faster and more efficient using the SM-2 spaced repetition algorithm - the same technique used by Anki and Duolingo.

Features

🎯 3 Parallel Learning Tracks

• Note Position - Find notes on the fretboard
• Scales - Master scale shapes
• Ear Training - Train your ear with audio
• Mix Mode - Practice all tracks in one session

🧠 Smart Review System

• SM-2 algorithm schedules reviews at optimal moments
• Cards you find easy appear less often, difficult ones more frequently
• Auto-adjusts based on response time
• Track progress and study streaks

📈 Tiered Progression System

• 4 difficulty tiers per track that unlock as you master cards
• Note Position: Basic (frets 0-5) → Extended (0-12) → Advanced (0-17) → Master (0-24)
• Scales: Gradual scale pattern unlocking
• Ear Training: Expanding note range as you improve

📱 Interactive Fretboard

• Touch-responsive fretboard for hands-on practice
• Visual feedback for correct/incorrect answers
• Multiple quiz formats: multiple choice, tap selection, multi-select

Tech Stack

Core: Expo 54 + React Native 0.76 + TypeScript 5.9 State: Zustand + MMKV (30x faster than AsyncStorage) UI: React Native SVG + Reanimated i18n: i18next (Korean/English support)

Quick Start

npm install
npm start

# Run on platform
npm run ios       # iOS simulator
npm run android   # Android emulator
npm run web       # Web browser

Development

npm run lint          # Biome lint check
npm run lint:fix      # Auto-fix issues
npm run typecheck     # TypeScript check
npm run format        # Format code

Project Structure

src/
├── app/              # Expo Router screens
│   ├── (tabs)/      # Home, Practice, Mastery, Settings
│   ├── quiz/        # Note, Scale, Ear, Mix quizzes
│   └── onboarding/  # 4-step onboarding flow
├── components/      # Reusable UI components
├── config/          # Tier configurations for each track
├── hooks/           # useSpacedRepetition (SM-2), useQuizSession
├── stores/          # Zustand global state
├── utils/           # SM-2, music theory, card generation
└── i18n/            # Internationalization (Korean/English)

Documentation

• Development Guide - Technical details, architecture, coding conventions
• Handoff Document - Project overview for new developers (Korean)
• BM/PM Analysis - Business & product analysis

Roadmap

Completed (v1.0)

• 3 parallel learning tracks (Note Position, Scales, Ear Training)
• Mix mode (cross-track practice)
• Tiered progression system (4 tiers per track)
• SM-2 spaced repetition algorithm
• Audio playback for ear training
• Statistics and progress tracking
• Mastery dashboard with track progress
• Smart review recommendation system
• 4-step onboarding flow
• Daily goal and streak tracking
• Push notifications
• Achievement badges
• Dev mode for tier testing

Planned (Post-Launch)

• Analytics infrastructure
• Ear training expansion (chord recognition, rhythm training)
• Monetization (subscription model)
• Supabase backend integration
• Social features (leaderboards, sharing)

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Status: MVP Complete Last Updated: Feb 2026

For detailed information, see docs/DEVELOPMENT.md