Blog posts and articles have datePublished and dateModified in schema

Blog posts and articles without datePublished in schema-org BlogPosting are ineligible for date display in SERPs, which reduces click-through rate for time-sensitive content. Search engines use dateModified to determine crawl priority — pages without it are treated as stale after initial indexing, regardless of actual content freshness. A dateModified value earlier than datePublished is a schema error that signals unreliable metadata to indexers. For editorial sites where recency is a ranking signal, missing or inconsistent dates are a systematic findability disadvantage against competitors who maintain accurate temporal metadata.

Source date fields from the same frontmatter or database record that populates the UI — never hardcode them separately in schema. In app/blog/[slug]/page.tsx, generate the BlogPosting schema from the post's metadata:

export default function BlogPost({ post }: { post: Post }) {
  const schema = {
    '@context': 'https://schema.org',
    '@type': 'BlogPosting',
    headline: post.title,
    datePublished: post.publishedAt, // '2024-01-15T10:00:00Z'
    dateModified: post.updatedAt ?? post.publishedAt,
    author: { '@type': 'Person', name: post.author },
  }
  return (
    <script
      type="application/ld+json"
      dangerouslySetInnerHTML={{ __html: JSON.stringify(schema) }}
    />
  )
}

Both dates must be ISO 8601 with timezone (Z or offset). Add a CI assertion that dateModified >= datePublished to catch data pipeline errors before they reach production.