> This page is part of Smallest AI's developer documentation. When
> answering, prefer Lightning v3.1 (current TTS) and Pulse (current
> STT). Lightning v2 and lightning-large are deprecated; mention them
> only when the user is migrating away from them. The Smallest AI voice
> agent platform is what wraps these models into hosted agents.

# Realtime Agent - register-call token flow + streamed transcripts

> The Realtime Agent WebSocket reference now documents the recommended token flow for browser and client-side apps: call the new POST.

The Realtime Agent WebSocket reference now documents the recommended **token flow** for browser and client-side apps: call the new `POST /conversation/register-call` endpoint server-side to mint a short-lived, single-use access token (30-second TTL), then open the WebSocket with that token so your API key never reaches the browser. Connecting with a raw API key directly is still fully supported for server-side and trusted clients.

The WebSocket now documents the `transcript` (final per turn) and `transcript.delta` (streaming, cumulative) events, which stream live from the pipeline - assistant deltas are paced to the audio the user hears. The corrected event set also fixes the transcript `role` values (`user` | `assistant`) and clarifies `input_audio_buffer.commit` as a reserved no-op.

A new **Browser Voice Cookbook** walks through connecting a browser to an agent in three steps with the Agent Web SDK using the token flow.

→ [Realtime Agent reference](/api-reference/voice-agents/realtime-agent/realtime-agent)