```javascript
export async function sendToAI(messages, {backend="provider", token=null} = {}) {
  if (backend === "local") {
    return fetch("http://127.0.0.1:11434/v1/chat", { 
      method:"POST", 
      headers:{"Content-Type":"application/json"}, 
      body: JSON.stringify({messages}) 
    })
    .then(r=>r.json())
    .then(d => d.choices?.[0]?.message?.content || JSON.stringify(d));
  } else if (backend === "bytebot-lambda") {
    return fetch("/api/v1/ai/chat", {
      method:"POST",
      headers:{"Content-Type":"application/json"},
      body: JSON.stringify({messages})
    }).then(r=>r.json()).then(d=>d.response);
  } else if (backend === "provider") {
    return fetch("https://api.openai.com/v1/chat/completions", {
      method:"POST",
      headers:{"Content-Type":"application/json","Authorization":"Bearer "+token},
      body: JSON.stringify({ model:"gpt-3.5-turbo", messages })
    }).then(r=>r.json()).then(d=>d.choices?.[0]?.message?.content);
  }
  return "No backend configured";
}

export function getAIConfig() {
  const defaultConfig = {
    backend: "provider",
    localEndpoint: "http://localhost:11434",
    providerToken: "",
    model: "gpt-3.5-turbo"
  };
  try {
    return JSON.parse(localStorage.getItem("aiConfig")) || defaultConfig;
  } catch {
    return defaultConfig;
  }
}

export function saveAIConfig(config) {
  localStorage.setItem("aiConfig", JSON.stringify(config));
}
```