realtime.response.audio_transcript.delta

Streaming text chunks as AI generates response

Triggered for each incremental text chunk as the AI generates its response. This event is sent multiple times during response generation. Handle this event to display AI responses in real-time as they’re generated.

Event Properties

type · string

Event type. Always "realtime.response.audio_transcript.delta" for this event.

data · object

Event data object containing response information.

data.content · string

The new text chunk to append to the accumulated response.

Example: "Hello there"

data.id · string

Unique identifier for this response. Used to track concurrent responses.

Example: "resp-123456"

data.response_id · string

Alternative field name for the response ID. May be present for compatibility.

Example: "resp-123456"

Example

{
  "type": "realtime.response.audio_transcript.delta",
  "data": {
    "content": "Hello there",
    "id": "resp-123456"
  }
}

Usage Example

const NavTalkMessageType = Object.freeze({
    REALTIME_RESPONSE_AUDIO_TRANSCRIPT_DELTA: "realtime.response.audio_transcript.delta",
    // ... other event types
});

let markdownBuffer = new Map();
let responseSpans = new Map();

async function handleReceivedMessage(data) {
    const nav_data = data.data;
    
    switch (data.type) {
        case NavTalkMessageType.REALTIME_RESPONSE_AUDIO_TRANSCRIPT_DELTA:
            const transcript = nav_data.content;
            const responseId = nav_data.id;
            
            // Accumulate content by response ID
            if (!markdownBuffer.has(responseId)) {
                markdownBuffer.set(responseId, "");
            }
            const existingBuffer = markdownBuffer.get(responseId);
            markdownBuffer.set(responseId, existingBuffer + transcript);
            
            // Get or create message element
            let aiMessageSpan = responseSpans.get(responseId);
            if (!aiMessageSpan) {
                // Create new message element
                aiMessageSpan = createMessageElement();
                responseSpans.set(responseId, aiMessageSpan);
            }
            
            // Update displayed content
            const fullContent = markdownBuffer.get(responseId);
            aiMessageSpan.innerHTML = marked.parse(fullContent);
            break;
    }
}