TwoLines

Most couples communicate throughout the day using transactional messaging apps like WhatsApp or iMessage. While these tools excel at logistical coordination ("Can you pick up groceries?"), they create an unintended side effect: emotional connection gets buried beneath administrative chatter.

On the other end of the spectrum, relationship wellness apps like Paired require 10 to 15 minutes of structured relationship therapy courses—creating cognitive friction that leads to user burnout and churn.

I built TwoLines to create an intimate, tactile digital space for couples. Released publicly on the Apple App Store, the application provides pairs of partners with low-friction shared micro-rituals: a simultaneous real-time drawing canvas (DuoDraw), double-blind daily connection questions, voice notes, audio love letters, and shared moods.

01 — Product Context: The Need for Intimate Micro-Rituals

Relationships in the modern world face a unique challenge: partners are physically separated for 8 to 12 hours a day due to work, travel, or long-distance arrangements.

During these hours, couples crave emotional touchpoints. However:

1. Phone and video calls require synchronized schedules and high cognitive commitment.
2. Text messaging is optimized for speed and utility, stripping away warmth and playfulness.
3. Clinical therapy apps feel like "relationship homework." Users download them with good intentions, but drop off after a week because filling out 20-minute compatibility surveys feels clinical.

The TwoLines Value Proposition

TwoLines focuses on shared micro-rituals that take less than 90 seconds to complete:

• DuoDraw: A collaborative live canvas where you can draw together simultaneously or leave a quick doodle for your partner to see when they wake up.
• Double-Blind Daily Questions: A daily prompt where neither partner can read the other's answer until both have submitted theirs.
• Love Letter Composer: Expressive audio and text letters with custom unwrapping animations.
• Mood Sharing & Little Wants: Ambient emotional awareness and shared wishlists.

02 — Target Audience & Market Landscape

Audience Segments

1. Long-Distance Couples (LDR): Crave tactile, real-time presence across time zones. Collaborative drawing and voice notes bridge physical distance without requiring scheduling.
2. Busy Co-Habitating Professionals: Working demanding schedules who need 60-second rituals to feel emotionally connected throughout the workday.
3. New Couples Establishing Habits: Looking for playful, low-pressure conversation starters to discover each other's perspectives without clinical therapy framing.

Competitor Comparison

03 — Product Walkthrough: Core User Journeys

TwoLines Mobile Interface & Experience

DuoDraw Collaborative Canvas

Real-time multi-user drawing canvas with shared color palettes, stroke interpolation, and background templates.

Love Letter Composer

Intimate multimedia composer for letters, audio recordings, and surprise unwrapping animations.

Real-Time Mood Sharing

Ambient emotional presence widget allowing partners to signal energy levels and feelings throughout the day.

Double-Blind Daily Rituals

Categorized daily connection prompts with non-recursive RLS enforcement ensuring answers remain hidden until both respond.

Voice Moments & Notes

Encrypted audio recordings streamed directly through Supabase Storage with custom waveform playback.

Shared Moments & Music

Shared relationship milestones and song recommendations integrated into the couple's private timeline.

04 — Mobile Architecture & Synchronization Engine

TwoLines is built on React Native and Expo Router, backed by Supabase for authentication, real-time channels, and PostgreSQL persistence:

  React Native / Expo Client (iOS & Android)
    │
    ├── UI Layer: Gesture Handler + Skia Canvas + Audio Player
    │
    ├── Canvas Sync Engine (useDrawingSync)
    │     ├── Optimistic Local Stroke Buffer (Immediate rendering)
    │     ├── Partner Cursor & Point Interpolation
    │     └── Connection Manager (NetInfo listener & reconnect loop)
    │
    ├── Offline Recovery Layer (OfflineStrokeQueue)
    │     ├── Local AsyncStorage queue (@twolines_offline_strokes_)
    │     └── Non-destructive batch replay on reconnect
    │
    └── Subscription Engine (RevenueCat SDK + In-App Paywalls V2)
                │
                ├── WebSocket (Realtime Sync & Presence)
                ├── HTTPS REST (PostgreSQL Operations)
                ▼
  Supabase Infrastructure
    ├── Authentication (Apple Sign-In & Supabase Auth)
    ├── Supabase Realtime (Workspace-scoped broadcast channels)
    ├── Supabase Storage (Encrypted audio notes & photos)
    └── PostgreSQL Database
          ├── workspaces (Pairing User 1 & User 2)
          ├── canvases & canvas_strokes (Timestamp-ordered strokes)
          └── Non-Recursive RLS Policies (Enforces double-blind answers)
                │
                ▼
  Apple StoreKit & RevenueCat Gateway
    └── Server-side receipt validation & auto-renewing subscriptions

05 — Deep Engineering Challenges

06 — Testing, Verification & Platform Readiness

• Automated Isolation Suites: Unit and integration tests verify workspace membership boundaries, ensuring no data leakage between different couple workspaces.
• EAS Build Pipelines: Configured with distinct development, preview, and production profiles for iOS and Android. Builds run with React Native New Architecture enabled.
• In-App Purchase Testing: Verified through RevenueCat sandbox environments, testing subscription renewals, billing grace periods, and cross-device entitlement synchronization.

07 — Monetization & Distribution Strategy

Business Model

• Subscription Architecture: Built around RevenueCat auto-renewing subscriptions with a 7-day free trial, offering Monthly ($9.99/mo) and Annual ($59.99/yr) plans.
• Couple-Level Entitlement: When one partner purchases a subscription, the entitlement unlocks premium features for the entire workspace, so both partners enjoy the benefits without paying twice.
• Organic Viral Loop: A user cannot experience TwoLines alone; they must invite their partner. Every onboarded user inherently brings a second active user through a personalized pairing code or QR scan.

08 — Lessons & Next Steps

1. Consumer mobile demands obsessive attention to perceived latency. Users forgive complex backend workflows taking 3 seconds, but they will immediately abandon a drawing canvas if a finger stroke lags by 100 milliseconds.
2. App Store compliance is an engineering discipline. Navigating privacy declarations, App Tracking Transparency, and subscription pricing prominence requires deep technical understanding of SDK network behavior.
3. Next Priorities:
   • Launch native iOS Home Screen Live Activities and Interactive Widgets for real-time doodle previews.
   • Roll out Android public Play Store availability.
   • Expand interactive mini-games on top of the collaborative canvas.

09 — Related Case Studies & Technical Writing

• Building an AI SaaS MVP: Architecture to Launch
• Fault Recovery in Agent Systems
• Context Management for AI Products