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Overview

These events are accepted by the Realtime servers via WebRTC datachannel from the client. Each event has a specific structure and purpose for managing realtime interactions.

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session.update

Send this event to update the session’s default configuration. The client may send this event at any time to update any field, except for voice. Note that once a session has been initialized with a particular model, it can’t be changed to another model using session.update. When the server receives a session.update, it will respond with a session.updated event showing the full, effective configuration. Only the fields that are present are updated. To clear a field like instructions, pass an empty string.

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Properties

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event_id
string
Client-generated ID used to identify this event.
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type
string
required
The event type, must be session.update.
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session
object
required
Realtime session object configuration.
{
    "event_id": "event_123",
    "type": "session.update",
    "session": {
        "modalities": ["text", "audio"],
        "instructions": "You are a helpful assistant.",
        "voice": "sage",
        "input_audio_format": "pcm16",
        "output_audio_format": "pcm16",
        "input_audio_transcription": {
            "model": "whisper-1"
        },
        "turn_detection": {
            "type": "server_vad",
            "threshold": 0.5,
            "prefix_padding_ms": 300,
            "silence_duration_ms": 500,
            "create_response": true
        },
        "tools": [
            {
                "type": "function",
                "name": "get_weather",
                "description": "Get the current weather...",
                "parameters": {
                    "type": "object",
                    "properties": {
                        "location": { "type": "string" }
                    },
                    "required": ["location"]
                }
            }
        ],
        "tool_choice": "auto",
        "temperature": 0.8,
        "max_response_output_tokens": "inf"
    }
}

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conversation.item.create

Add a new Item to the Conversation’s context, including messages, function calls, and function call responses. This event can be used both to populate a “history” of the conversation and to add new items mid-stream, but has the current limitation that it cannot populate assistant audio messages.

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Properties

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event_id
string
Client-generated ID used to identify this event.
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type
string
required
The event type, must be conversation.item.create.
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previous_item_id
string
The ID of the preceding item after which the new item will be inserted. If not set, the new item will be appended to the end of the conversation.
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item
object
required
The item to add to the conversation.
{
    "event_id": "event_345",
    "type": "conversation.item.create",
    "previous_item_id": null,
    "item": {
        "id": "msg_001",
        "type": "message",
        "role": "user",
        "content": [
            {
                "type": "input_text",
                "text": "Hello, how are you?"
            }
        ]
    }
}

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response.create

This event instructs the server to create a Response, which means triggering model inference. When in Server VAD mode, the server will create Responses automatically.

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Properties

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event_id
string
Client-generated ID used to identify this event.
​
type
string
required
The event type, must be response.create.
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response
object
required
Create a new Realtime response with these parameters.
{
    "event_id": "event_234",
    "type": "response.create",
    "response": {
        "modalities": ["text", "audio"],
        "instructions": "Please assist the user.",
        "voice": "sage",
        "output_audio_format": "pcm16",
        "tools": [
            {
                "type": "function",
                "name": "calculate_sum",
                "description": "Calculates the sum of two numbers.",
                "parameters": {
                    "type": "object",
                    "properties": {
                        "a": { "type": "number" },
                        "b": { "type": "number" }
                    },
                    "required": ["a", "b"]
                }
            }
        ],
        "tool_choice": "auto",
        "temperature": 0.8,
        "max_output_tokens": 1024
    }
}