Optimize assistant dynamic prompt

[xbol0]

Assistant dynamic prompt is an awesome feature, I read the implementation at

chat-ui/src/routes/conversation/[id]/+server.ts

Line 385 in 18fba9f

if (assistantHasDynamicPrompt && preprompt) {

I felt its implementation is a bit too simple, here's my some suggestions (from line 385):

// The result always replace to system prompt,
// so we can skip the data retrieve if there do not provided system prompt
if (assistantHasDynamicPrompt && preprompt && messagesForPrompt[0].from === "system") {
  // process the preprompt
  const urlRegex = /{{\s?url=(.*?)\s?}}/g;

  // define a max loop count
  // This is a recursive loop,
  // If the result contains the '{{url=xxxx}}' format with same content url,
  // it will diving into a infinite loop
  let match, maxLoop = 10; // it can be define at other files
  while ((match = urlRegex.exec(preprompt)) !== null && maxLoop--) {
  try {
  // Add programmable placeholder for more context,
  // It's very useful because the user prompt is always provided,
  // the service can return the targeted result.
  // The assistant's author can configure it as a path parameter or a query
  // eg. https://xxx.com/%S or https://xxx.com/?q=%S
  let preUrl = match[1];
  preUrl = preUrl.replaceAll('%S', messagesForPrompt[0].content) // may it should be encoded
  // Other placeholder
  // Such as %R for random seed, bypass cache
  // %T for timestamp
  const url = new URL(preUrl);
  if (await isURLLocal(url)) {
	  throw new Error("URL couldn't be fetched, it resolved to a local address.");
  }
  
  // Add more identity headers
  // If the service contains many response format,
  // these headers can tell it which correct format should be returned
  const res = await fetch(url.href, {
    headers: {
      "accept": "text/plain, text/markdown, text/*;q=0.9, */*;q=0.8",
      "user-agent": "ChatUI/0.8",
    },
  });
  
  if (!res.ok) {
	  throw new Error("URL couldn't be fetched, error " + res.status);
  }
  const text = await res.text();
  preprompt = preprompt.replaceAll(match[0], text);
  } catch (e) {
  preprompt = preprompt.replaceAll(match[0], (e as Error).message);
  }
  }
  
  // if (messagesForPrompt[0].from === "system") {
  messagesForPrompt[0].content = preprompt;
  //}
  }