src/plugin-sdk/text-chunking.ts

export function chunkTextForOutbound(text: string, limit: number): string[] {
  if (!text) {
    return [];
  }
  if (limit <= 0 || text.length <= limit) {
    return [text];
  }
  const chunks: string[] = [];
  let remaining = text;
  while (remaining.length > limit) {
    const window = remaining.slice(0, limit);
    const lastNewline = window.lastIndexOf("\n");
    const lastSpace = window.lastIndexOf(" ");
    let breakIdx = lastNewline > 0 ? lastNewline : lastSpace;
    if (breakIdx <= 0) {
      breakIdx = limit;
    }
    const rawChunk = remaining.slice(0, breakIdx);
    const chunk = rawChunk.trimEnd();
    if (chunk.length > 0) {
      chunks.push(chunk);
    }
    const brokeOnSeparator = breakIdx < remaining.length && /\s/.test(remaining[breakIdx]);
    const nextStart = Math.min(remaining.length, breakIdx + (brokeOnSeparator ? 1 : 0));
    remaining = remaining.slice(nextStart).trimStart();
  }
  if (remaining.length) {
    chunks.push(remaining);
  }
  return chunks;
}