title: Frontend & Navigation
aliases: [Navigation Graph, Screen Catalog]
tags: [3netra/wiki, frontend, navigation, diagrams]
product: 3netra Meta Android App
source_repository: 3Netra-ai/3n_meta_android
source_ref: origin/prod
source_revision: b48aada8fd5427b5db0c02945569963c4ae543c8
last_verified: 2026-08-06
up: "[[Home]]"

Frontend & Navigation

Single-activity Compose app. Start destination computed in MainActivity after Supabase session resolves:

user == null               → "login"
!permissions_asked         → "permissions"
!onboarding_complete       → "onboarding_welcome"
else                       → "main"

Navigation Graph

flowchart TD
    LOGIN[login<br/>LoginScreen] -->|success| PERM{permissions_asked?}
    LOGIN --> SU[signup<br/>SignUpScreen] -->|verify email| LOGIN
    PERM -->|no| PERMISSIONS[permissions<br/>PermissionRationaleScreen]
    PERM -->|yes| ONB{onboarding_complete?}
    PERMISSIONS --> ONB
    ONB -->|no| OW[onboarding_welcome] --> OG[onboarding_grade<br/>legacy K–6 labels in code] --> OP[onboarding_pair<br/>BluetoothPairingScreen]
    OP -->|connect or skip| MAIN
    ONB -->|yes| MAIN

    MAIN["main — MainAppScreen (bottom bar)"]

    subgraph INNER["Inner NavHost (bottom tabs)"]
        HOME[home_tab<br/>StudentHomeScreen]
        CHAT[chat_tab<br/>AssistantChatScreen 'Be My Eyes']
        STORY[story_tab<br/>TodaysStoryScreen]
        FRIENDS[classmates_tab<br/>ClassmatesScreen]
    end
    MAIN --> INNER

    HOME -->|quick actions| SCENE["scene_description/{mode}<br/>Scene|Read|Classroom|People|Emotions"]
    HOME --> LN[lecture_notes<br/>LectureNotesScreen]
    HOME --> SETTINGS[settings<br/>SettingsScreen]
    SETTINGS --> COMP[companion_select<br/>CompanionSelectScreen]
    FRIENDS -->|FAB + Teacher PIN| FACE[face_registration<br/>FaceRegistrationScreen]

    LEGACY["dashboard → glassesConfig / chatHistory<br/>(orphaned legacy routes)"]

Bottom bar (4 tabs): Home 🏠 · Chat ✈️ · My Story ❤ · Friends 👥. Settings & Lecture Notes are pushed from Home, not tabs.

Screen Catalog

Home quick actions (2×3 grid): 🔍 What do I see? · 📖 Read this · 🏫 Classroom · 👤 Who's here? · ❤️ Feelings · 📝 Notes.

Frontend Flow Chart (core capture loop)

sequenceDiagram
    participant U as Student
    participant H as Home/Scene Screen
    participant B as BluetoothService
    participant W as WearableCameraService
    participant F as FaceNet + EncryptedStore
    participant A as SupabaseAiService
    participant L as Supabase chat-vision
    participant T as Android TTS
    participant S as Supabase

    U->>H: tap a scene-mode chip
    H->>W: capturePhoto()
    W->>W: MWDAT session → 15fps stream → photo bytes
    W-->>H: ByteArray (or error "glasses connected?")
    opt People / Emotions mode
        H->>F: embedding → cosine vs Supabase-fetched embeddings (>0.5)
        F-->>H: match → "I see {name}!" (People: done)
    end
    H->>A: analyzeImage(bytes, mode prompt)
    A->>L: invoke chat-vision
    L-->>A: model response (discarded)
    A-->>H: fixed "AI response received"
    H->>B: logLocalSession(mode, text)
    B->>S: insert sessions row
    H->>T: speak(text) via ChildVoicePersonaManager
    T-->>U: audio narration

State Management

• Auth: MainViewModel StateFlow over Supabase SessionStatus
• Connection / chat history: BluetoothService StateFlows (connectionState, chatHistory) shared app-wide
• Prefs (3n_prefs): permissions_asked, onboarding_complete, student_grade, student_nickname, companion_id, school_mode_enabled, tts_speed, high_contrast, reduce_motion, battery_saver
• Secure prefs: teacher PIN (3netra_secure, BCrypt). EncryptedFaceStorageManager exists but is not called by the active face flow.

Voice Command Wiring

VoiceCommandService can broadcast com.threenetra.app.VOICE_COMMAND, and Home registers handlers. At this revision, no source path emits the documented WHAT_DO_I_SEE/CLASSROOM_MODE broadcasts or connects a DAT long-press callback; onLongPress() only starts the Android recognition service when invoked. See 04-User-Journeys.