First use [[onStateChanged]] to detect changes in the session state. Then use forceRefocus to force the the app to continue working. If state equals UNPAIRED that means the host account user has manually de authenticated the session through the app.

  client.onStateChanged(state=>{
    console.log('statechanged', state)
    if(state==="CONFLICT" || state==="UNLAUNCHED") client.forceRefocus();

    if(state==='UNPAIRED') console.log('LOGGED OUT!!!!')
  });

For more information see: STATE