function handleModelMessage()

in websocket-server/src/sessionManager.ts [154:209]
50 lines of code
12 McCabe index (conditional complexity)

function handleModelMessage(data: RawData) {
  const event = parseMessage(data);
  if (!event) return;

  jsonSend(session.frontendConn, event);

  switch (event.type) {
    case "input_audio_buffer.speech_started":
      handleTruncation();
      break;

    case "response.audio.delta":
      if (session.twilioConn && session.streamSid) {
        if (session.responseStartTimestamp === undefined) {
          session.responseStartTimestamp = session.latestMediaTimestamp || 0;
        }
        if (event.item_id) session.lastAssistantItem = event.item_id;

        jsonSend(session.twilioConn, {
          event: "media",
          streamSid: session.streamSid,
          media: { payload: event.delta },
        });

        jsonSend(session.twilioConn, {
          event: "mark",
          streamSid: session.streamSid,
        });
      }
      break;

    case "response.output_item.done": {
      const { item } = event;
      if (item.type === "function_call") {
        handleFunctionCall(item)
          .then((output) => {
            if (session.modelConn) {
              jsonSend(session.modelConn, {
                type: "conversation.item.create",
                item: {
                  type: "function_call_output",
                  call_id: item.call_id,
                  output: JSON.stringify(output),
                },
              });
              jsonSend(session.modelConn, { type: "response.create" });
            }
          })
          .catch((err) => {
            console.error("Error handling function call:", err);
          });
      }
      break;
    }
  }
}