Validate before persisting a batch write

import { UPGClient, type CreateNodeArgs } from '@unified-product-graph/sdk'

const upg = new UPGClient({ file: './product.upg' })

async function safeBulkCreate(items: CreateNodeArgs[]) {
  const before = await upg.health()
  const created = await Promise.all(items.map(i => upg.nodes.create(i)))

  const report = await upg.verify()
  if (!report.ok) {
    console.error('rollback — validation failed:', report.contentValidationErrors)
    for (const { node } of created) {
      await upg.nodes.delete(node.id)
    }
    return null
  }

  const after = await upg.health()
  console.log(`+${created.length} nodes · health ${before.score} → ${after.score}`)
  return created
}