Real-Time Architecture & WebSockets

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Overview

• Unit reservation locks must flash across all sales lounges instantly to prevent double-booking
• Inbound WhatsApp customer replies must appear in the team inbox without browser reloads
• Autonomous voice agents require raw bidirectional PCM audio streaming over low-latency WebSockets
• Manager employee trackers require live updates when telecallers start or end calls

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Gateway Topology

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The 3 Dedicated Gateways

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1. Chat & Notification Gateway (/chat)

• Staff-to-Staff Messaging: Real-time direct messages and project channel dialogues between field executives and managers.
• Push Notification Broadcasts: Transmits real-time alerts when a lead is assigned or an executive approves a discount.
• Presence Tracking: Displays live online/offline indicators for floor agents.

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Room Scoping Patterns

// Join personal notification channel
socket.join(`user:${userId}`);

// Join project lounge channel for hold announcements
socket.join(`project:${projectId}`);

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2. WhatsApp Real-Time Gateway (/whatsapp)

• Instant Inbound Push: Broadcasts incoming customer text, attachments, and button taps the millisecond Meta’s webhook posts an incoming reply.
• Delivery Receipts: Updates message ticks (sent to delivered to read) dynamically.
• Agent Typing Indicators: Broadcasts when a colleague or customer is actively composing a response.

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3. Voice Media Stream Gateway (/voice/stream)

• Low-Latency Audio Bridge: Connects raw PSTN audio streams from telephony carriers (Telnyx TeXML or Twilio Media Streams) to LLM voice engines.
• Audio Codec: Streams bidirectional audio/x-mulaw (8kHz, 8-bit mono) or 16-bit linear PCM.
• Barge-In Interruption Detection: Detects user speech interruption and immediately clears the playback buffer to halt the AI agent from speaking over the prospect.

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WebSocket Authentication Law

@WebSocketGateway({ cors: { origin: '*' } })
export class ChatGateway implements OnGatewayConnection {
  async handleConnection(client: Socket) {
    const token =
      client.handshake.auth?.token ||
      client.handshake.headers?.authorization?.replace('Bearer ', '');

    if (!token) {
      client.disconnect(true);
      return;
    }

    const session = await validateBetterAuthSession(token);
    if (!session) {
      client.disconnect(true);
      return;
    }

    // Attach authenticated identity to socket instance
    client.data.user = session.user;
  }
}

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Horizontal Scaling with Redis Pub/Sub