function createUpdateFollowUp() {
  const clean = (value, limit) => String(value || '').replace(/\s+/g, ' ').trim().slice(0, limit);
  const safeRepository = value => {
    const candidate = String(value || '');
    return /^[A-Za-z0-9_.-]+\/[A-Za-z0-9_.-]+$/.test(candidate) &&
      candidate.split('/').every(part => part !== '.' && part !== '..') ? candidate : '';
  };
  const safeUrl = value => {
    try {
      const parsed = new URL(String(value || ''));
      return parsed.protocol === 'https:' || parsed.protocol === 'http:' ? parsed.href : '';
    } catch (_error) { return ''; }
  };

  function draft(detail = {}) {
    const source = safeUrl(detail.url || detail.latest_comment?.url);
    const context = clean(detail.latest_comment?.body || detail.subject_body, 9000);
    const title = clean(detail.title, 228);
    const sections = [];
    if (source) sections.push('Source: ' + source);
    if (context) sections.push('Latest context:\n> ' + context.replace(/\n/g, '\n> '));
    return {
      repository: safeRepository(detail.repository),
      title: ('Follow up: ' + (title || 'Unread update')).slice(0, 240),
      body: sections.join('\n\n').slice(0, 9500),
    };
  }

  return { draft };
}

if (typeof module !== 'undefined' && module.exports) module.exports = createUpdateFollowUp;