frontend/src/lib/prompt-utils.ts

// Sentinel delimiter used by the backend (U+241F – SYMBOL FOR UNIT SEPARATOR).
export const MULTI_SNIPPET_DELIMITER = "\u241F";

/**
 * Split a concatenated prompt string into individual snippets.
 * If the delimiter is not found, returns the original string as a single-item array.
 */
export function splitPrompt(text: string | undefined | null): string[] {
  if (!text) return [];

  // Prefer the new sentinel delimiter; fall back to legacy "|||" so that
  // previously stored knowledge-graphs continue to display correctly.
  let parts: string[];
  if (text.includes(MULTI_SNIPPET_DELIMITER)) {
    parts = text.split(MULTI_SNIPPET_DELIMITER);
    console.debug(
      `splitPrompt: Using sentinel delimiter, found ${parts.length} parts`
    );
  } else if (text.includes("|||")) {
    parts = text.split("|||");
    console.debug(
      `splitPrompt: Using legacy delimiter, found ${parts.length} parts`
    );
  } else {
    parts = [text];
    console.debug(`splitPrompt: No delimiter found, single part`);
  }

  const result = parts
    .map((part) => part.trim())
    .filter((part) => part.length > 0);

  console.debug(
    `splitPrompt: After trim/filter, ${result.length} parts remain`
  );
  if (result.length > 1) {
    result.forEach((part, idx) => {
      const preview = part.substring(0, 50).replace(/\n/g, "\\n");
      console.debug(`splitPrompt: part[${idx}]: ${preview}...`);
    });
  }

  return result;
}

/**
 * Remove the numbered trace prefix (e.g., "<L25> ") from a prompt snippet for UI display.
 */
export function cleanNumberedPrefix(text: string): string {
  if (!text) return text;
  return text.replace(/^<L\d+>\s*/, "");
}