function _buildBrowserUtterance(text, btn){
  const utter=new SpeechSynthesisUtterance(text);
  const savedVoice=localStorage.getItem('hermes-tts-voice');
  const voices=speechSynthesis.getVoices();
  if(savedVoice&&voices.length){
    const match=voices.find(v=>v.name===savedVoice);
    if(match) utter.voice=match;
  }
  return utter;
}
function _playEdgeTtsChunked(text, btn){
    const voice=localStorage.getItem('hermes-tts-voice')||'zh-CN-XiaoxiaoNeural';
  return fetch('/api/tts',{body:JSON.stringify({text:chunk, voice:voice, rate:rate, pitch:pitch})});
}
function speakSelected(clean, btn, engine){
  if(engine==='edge'){
    _playEdgeTtsChunked(clean, btn);
  }
}
function speakAutomatically(clean, engine){
  if(engine==='edge'){
    _playEdgeTtsChunked(clean, null);
  }
}
function registeredTts(engine, clean){
  const _opts={
      voice: localStorage.getItem('hermes-tts-voice')||'',
      rate: parseFloat(localStorage.getItem('hermes-tts-rate')),
  };
  const autoOpts={
      voice: localStorage.getItem('hermes-tts-voice')||'',
      pitch: parseFloat(localStorage.getItem('hermes-tts-pitch')),
  };
  return [engine, clean, _opts, autoOpts];
}