gemini-compat-endpoint

// Proper prompt preprocessor using LM Studio SDK types.
// - Text/doc attachments are parsed server-side and injected into the user message text.
// - Images are not accepted by the UI for this generator (no image capability flag),
//   but we support inline image references written by the user (markdown or [image: URL]).

import {
  type PromptPreprocessorController,
  type ChatMessage,
} from "@lmstudio/sdk";

export async function preprocess(ctl: PromptPreprocessorController, userMessage: ChatMessage) {
  try {
    const originalText = userMessage.getText();

    // 1) Pull non-image files attached in this message and parse them to text
    const files = userMessage.consumeFiles(ctl.client, file => file.type !== "image");
    let injected = "";
    for (const file of files) {
      const { content } = await ctl.client.files.parseDocument(file, { signal: ctl.abortSignal });
      const snippet = content.length > 200_000 ? content.slice(0, 200_000) + "\n...[truncated]" : content;
      injected += `\n\n[Attachment: ${file.name}]\n${snippet}\n`;
    }

    // 1b) Pull image files and create wrappers for them (enables UI attachment support)
    const imageFiles = userMessage.consumeFiles(ctl.client, file => file.type === "image");
    const wrappers: string[] = [];
    for (const file of imageFiles) {
      // Get file path (FileHandle.getFilePath() is async)
      const filePath = await file.getFilePath();
      // Create file:// URI wrapper so reconcileAttachments() can find and process them
      const fileUri = `file://${filePath}`;
      wrappers.push(`[[LMSTUDIO_ATTACHMENT: ${JSON.stringify({ kind: "image", url: fileUri })}]]`);
    }

    // 2) Inline image references (markdown or [image: URL]) → kept as-is; generator will convert
    //    them to image_url content parts using wrappers we add below.
    const inlineImageUrls = new Set<string>();
    const mdImg = /!\[[^\]]*\]\((https?:[^\s)]+)\)/g;
    let m: RegExpExecArray | null;
    while ((m = mdImg.exec(originalText)) !== null) inlineImageUrls.add(m[1]);
    const tagImg = /\[image:\s*(https?:[^\]\s]+)\s*\]/gi;
    while ((m = tagImg.exec(originalText)) !== null) inlineImageUrls.add(m[1]);
    for (const url of inlineImageUrls) {
      // Add inline URL wrappers to the existing wrappers array
      wrappers.push(`[[LMSTUDIO_ATTACHMENT: ${JSON.stringify({ kind: "image", url })}]]`);
    }

    if (injected.length === 0 && wrappers.length === 0) return userMessage;

    const combined = `${originalText}${injected}${wrappers.length ? "\n\n" + wrappers.join("\n") : ""}`.trim();
    userMessage.replaceText(combined);
    return userMessage;
  } catch (err) {
    return userMessage;
  }
}