Privacy-First Body Awareness PWA Built in 7 Days
How we delivered a complete wellness app with Google OAuth, AI-powered insights, offline support, and i18n - all while keeping user data 100% local.
Key Results
The Challenge
A long-time friend in need approached us with a unique wellness app vision. Unlike typical headache trackers focused on migraines and medical tracking, they wanted an awareness training app - something that helps users recognize body signals before headaches develop.
The specific requirements included:
- Track tension headaches with patterns and triggers
- Educational content about body awareness and interoception signals
- Progressive feature unlocking (don't overwhelm new users)
- Simple input methods: buttons, dropdowns, or natural language
- 100% local data storage - no server-side data, complete privacy
The challenge: deliver a production-ready PWA with OAuth, AI insights, offline support, and internationalization - while keeping all user data on their device.
Key Quote from Requirements:
"I don't want it to be overwhelming leading to analysis paralysis. Input could be from a fixed list or button or drop-down or even a natural language text at irregular intervals."
The Solution
We leveraged our AI-powered development platform to deliver the complete solution in 7 days:
Clean Architecture Implementation
- Domain layer with User, HeadacheEntry, CheckIn, Streak entities
- Use cases for logging, insights, dashboard data
- Interface adapters with 9 Zustand stores
- IndexedDB for local-first persistence
Four-Phase User Journey
The app implements progressive feature unlocking:
- LEARN (Week 1): Educational content + basic intensity logging
- NOTICE (Week 2-3): Headache types, location, body tension, mood
- UNDERSTAND (Week 4+): AI-powered insights with BYOK model
- PREVENT (Ongoing): Streak tracking, gamification, alerts
Real-time Collaboration via Slack
- Requirements gathered through structured questionnaire
- Each feature tracked in dedicated threads
- Instant feedback loop during development
- All decisions documented and traceable
Privacy-First Architecture
All data is stored locally in IndexedDB, namespaced by user ID. Each user gets their own isolated database with stores for logs, check-ins, and settings. No data ever leaves the device.
BYOK AI Integration
Users provide their own API keys for AI insights - no API costs for the app, complete data privacy. The app uses Vercel AI SDK with support for both OpenAI and Anthropic models.
Technologies Used
The Results
Delivered in Record Time
The complete PWA was delivered in 7 days from initial requirements to production:
Day 1: Project setup, Clean Architecture foundation, PWA configuration
Day 2: CI/CD pipeline, onboarding wizard, E2E tests
Day 3: Quick logging, dashboard home, state management
Day 4-5: Insights page, i18n (English + Japanese)
Day 6: Google OAuth, multi-user data isolation
Day 7: UX polish, analytics, production deployment
Live Application
- Production URL: headache-awareness-trainer.vercel.app
- GitHub Repository: kanaerulabs/headache-awareness-trainer
Technical Deliverables
| Metric | Value |
|---|---|
| Production Code | 23,662 lines |
| Test Code | 61,608 lines |
| Code:Test Ratio | 1:2.6 |
| UI Components | 24+ with Storybook |
| Languages | English + Japanese |
| Lighthouse PWA Score | 90+ |
Key Features Delivered
- Progressive Web App: Full offline support, Add to Home Screen
- Google OAuth: NextAuth.js v5 with session management
- AI Insights: BYOK model with OpenAI/Anthropic support
- i18n: Complete English and Japanese translations
- Privacy-First: 100% local data storage in IndexedDB
- Progressive Unlocking: Features unlock based on engagement
What Made This Possible
- AI agents working in parallel on different features
- Automated TDD harness ensuring quality at speed
- Real-time Slack collaboration eliminating delays
- Clean Architecture enabling rapid, confident development
- Privacy-first design simplifying the architecture (no backend needed)
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