Opal WebSocket Protocol

{
  "initializeSessionRequest": {
    "inputAudioLine": {
      "sampleRate": 16000,
      "channelCount": 1,
      "sampleFormat": "SIGNED_16_BIT"
    },
    "outputAudioLine": {
      "sampleRate": 16000,
      "channelCount": 1,
      "sampleFormat": "SIGNED_16_BIT"
    },
    "vadConfiguration": {
      "confidenceThreshold": 0.5,
      "minVolume": 0,
      "startDuration": { "seconds": 0, "nanos": 200000000 },
      "stopDuration": { "seconds": 0, "nanos": 500000000 },
      "backbufferDuration": { "seconds": 1, "nanos": 0 }
    },
    "inferenceConfiguration": {
      "systemPrompt": "You are a helpful assistant.",
      "temperature": 0.7
    },
    "supportsPlaybackReporting": true
  }
}

{
  "reconfigureSessionRequest": {
    "inputAudioLine": {
      "sampleRate": 48000,
      "channelCount": 1,
      "sampleFormat": "SIGNED_16_BIT"
    },
    "inferenceConfiguration": {
      "systemPrompt": "You are now a billing specialist."
    }
  }
}

{
  "updateToolDefinitionsRequest": {
    "toolDefinitions": [
      {
        "name": "get_weather",
        "description": "Get current weather for a location",
        "parameters": {
          "type": "object",
          "properties": {
            "location": { "type": "string" }
          },
          "required": ["location"]
        }
      }
    ]
  }
}

{
  "toolCallResponse": {
    "id": "call_abc123",
    "result": "{\"temperature\": 22, \"condition\": \"sunny\"}"
  }
}

{
  "triggerInference": {
    "extraInstructions": "Greet the user warmly and ask how you can help."
  }
}

{
  "exportChatHistoryRequest": {
    "awaitPending": true
  }
}

{
  "playbackPositionReport": {
    "bytesPlayed": 32000
  }
}

{
  "directSpeech": {
    "text": "Please hold, transferring your call.",
    "includeInHistory": false
  }
}

{
  "conversationQuery": {
    "prompt": "You are a sentiment analyzer.",
    "instructions": "This is the chat history between an assistant and a customer. Do not reply to the chat in any way; only create a brief summary of the entire chat and describe the key points as briefly as possible. 1-2 sentences without line breaks. Reply directly with the summary, no introductions like: 'Okay, here is a brief summary: ...' Example summary: 'Customer requested a callback; conversation positive.'"
  }
}

{
  "modelTextFragment": {
    "text": "Hello, how can I help you?"
  }
}

{
  "modelAudioChunk": {
    "audio": {
      "data": "<binary-pcm-data>"
    },
    "transcript": "Hello, how can I help you?"
  }
}

{
  "toolCallRequest": {
    "id": "call_abc123",
    "name": "get_weather",
    "parameters": {
      "location": "Amsterdam"
    }
  }
}

{
  "playbackClearBuffer": {}
}

{
  "responseBegin": {}
}

{
  "responseEnd": {}
}

{
  "chatHistory": {
    "messages": [
      {
        "role": "user",
        "delivery_status": "DELIVERY_COMPLETE",
        "ephemeral": false,
        "content": [
          {
            "type": "input_audio",
            "transcription": "What time is it?"
          }
        ]
      },
      {
        "role": "assistant",
        "delivery_status": "DELIVERY_COMPLETE",
        "ephemeral": false,
        "content": [
          {
            "type": "text",
            "text": "It's currently 3:45 PM.",
            "tts_audio": null
          }
        ]
      }
    ]
  }
}

{
  "error": {
    "category": "ERROR_CONFIGURATION",
    "message": "Invalid sample rate: must be between 8000 and 48000",
    "traceId": "abc-123-xyz"
  }
}

{
  "userTranscriptionResult": {
    "turnId": 3,
    "text": "What time is it?",
    "language": "en"
  }
}

{
  "conversationQueryResult": {
    "text": "positive"
  }
}