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Your Command Center: UserSessions

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What is a UserSession?

• Maintains the WebSocket connection to the glasses
• Manages all the specialized services (managers)
• Tracks which apps are running
• Handles all message routing
• Survives temporary disconnections

// Simplified view of UserSession
class UserSession {
  userId: string;                    // alex@example.com
  websocket: WebSocket;              // Connection to glasses
  appWebsockets: Map<string, WebSocket>; // Connections to apps
  startTime: Date;                   // When session started
  
  // The managers (our departments)
  appManager: AppManager;
  audioManager: AudioManager;
  displayManager: DisplayManager;
  // ... and more
}

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Meet the Managers

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🎯 AppManager - The App Orchestrator

// What it tracks for each app
{
  packageName: "com.translate.app",
  state: "RUNNING" | "GRACE_PERIOD" | "RESURRECTING" | "STOPPING",
  websocket: WebSocket,
  lastHeartbeat: Date
}

• Starting and stopping apps
• Monitoring app health with heartbeats
• Handling app reconnections
• Managing the 20-second grace period when apps disconnect

1. Finds the translator app in installed apps
2. Notifies the app via webhook to start
3. Waits for app to connect via WebSocket
4. Monitors the app’s health

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🎤 AudioManager - The Sound Department

// Managing audio streams
audioManager.startStreaming();  // Start receiving audio from glasses
audioManager.stopStreaming();   // Stop audio stream
audioManager.playAudio(audioData, format); // Play audio on glasses

• Receiving audio streams from glasses microphone
• Buffering audio data for processing
• Sending audio to glasses speakers
• Managing audio format conversions

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📺 DisplayManager - The Visual Controller

// Display update request
displayManager.updateDisplay({
  type: "cards",
  cards: [{
    title: "Weather",
    body: "72°F and sunny"
  }]
});

• Rendering layouts from apps
• Enforcing the 200-300ms throttle between updates
• Managing display queues
• Preventing display spam

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🎙️ TranscriptionManager - The Speech-to-Text Expert

// Start transcribing
transcriptionManager.startTranscription("en-US");

// Receive transcription events
transcriptionManager.on('transcription', (text) => {
  console.log("User said:", text);
});

• Managing transcription providers (Deepgram, Assembly, etc.)
• Streaming audio to transcription services
• Handling multiple language streams
• Distributing transcripts to subscribed apps

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📸 PhotoManager - The Camera Controller

// App requests a photo
photoManager.requestPhoto();

// Photo arrives from glasses
photoManager.on('photoReceived', (photoData) => {
  // Process and distribute to requesting app
});

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🌐 MicrophoneManager - The Audio Gate

// Turn microphone on/off
microphoneManager.setMicrophoneState(true);  // On
microphoneManager.setMicrophoneState(false); // Off

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📊 DashboardManager - The Always-On Display

// Update dashboard content
dashboardManager.updateContent({
  text: "3 new messages",
  priority: "high"
});

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How Managers Work Together

1. AudioManager receives the audio stream
2. TranscriptionManager converts it to text: “Take a photo”
3. AppManager routes the transcript to subscribed apps
4. App recognizes the command and tells PhotoManager
5. PhotoManager sends photo request to glasses
6. Glasses capture photo and send it back
7. PhotoManager receives photo and gives it to the app
8. App processes photo and uses DisplayManager to show “Photo saved!”

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Session Lifecycle

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Birth: Session Creation

const session = new UserSession(userId, websocket);
// All managers are initialized
session.appManager = new AppManager(session);
session.audioManager = new AudioManager(session);
// ... etc

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Life: Active Session

• Heartbeat runs every 10 seconds
• Messages flow between glasses and apps
• Managers handle their specific duties
• Everything is logged for debugging

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Near-Death: Disconnection

• 30-second grace period begins
• Apps enter “resurrecting” state
• Session waits for reconnection
• No data is lost

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Resurrection or Death

• WebSocket is updated
• Apps are notified
• Everything continues normally

• Session is cleaned up
• All managers are destroyed
• Apps are notified of session end
• Memory is freed

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Session Storage

class SessionStorage {
  private static sessions = new Map<string, UserSession>();
  
  static getSession(userId: string): UserSession | undefined {
    return this.sessions.get(userId);
  }
  
  static addSession(session: UserSession) {
    this.sessions.set(session.userId, session);
  }
}

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Best Practices

1. Always check session exists before using it
2. Use the appropriate manager for each task
3. Let managers handle their domain - don’t bypass them
4. Clean up resources when sessions end
5. Log important events for debugging

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What’s Next?