Actions on google 更改意图时更新CANAV

当我调用新意图时，更新到新状态时遇到问题。我的 交互式画布需要根据我发送的命令更改状态， 但事实并非如此。我怎样才能使它正常工作

这是我的网络钩子的一部分。如您所见，当触发“DRAWLINE”意图时，“DRAWLINE”命令被发送到url，网页需要更改为不同的部分。但是，我的网页似乎没有更新

app.handle('WELCOME', (conv) => {
  if (!conv.device.capabilities.includes('INTERACTIVE_CANVAS')) {
    conv.add('Sorry, this device does not support Interactive Canvas!');
    conv.scene.next.name = 'actions.page.END_CONVERSATION';
    return;
  }
  conv.add('this is welcome intent');
  conv.add(new Canvas({
      url: CANVAS_URL,
      data: {
        command: 'WELCOME',
      },
  }));
});

app.handle('DRAWLINE', (conv) => {
  if (!conv.device.capabilities.includes('INTERACTIVE_CANVAS')) {
    conv.add('Sorry, this device does not support Interactive Canvas!');
    conv.scene.next.name = 'actions.page.END_CONVERSATION';
    return;
  }
  conv.add('this is drawLine');
  conv.add(new Canvas({
      url: CANVAS_URL,
      data: {
        command: 'DRAWLINE',
      },
    }));
});