RealtimeServerEventConversationItemTruncated

Returned when an earlier assistant audio message item is truncated by the
client with a conversation.item.truncate event. This event is used to
synchronize the server's understanding of the audio with the client's playback.

This action will truncate the audio and remove the server-side text transcript
to ensure there is no text in the context that hasn't been heard by the user.

{
    "event_id": "string",
    "type": "conversation.item.truncated",
    "item_id": "string",
    "content_index": 0,
    "audio_end_ms": 0
}