I run four Astro sites. Three of them shipped the same SEO bug for months. Every blog post on those sites told Twitter, Facebook, and LinkedIn that it was a website — not an article . Here is what happened, why I did not catch it sooner, and the one-line build check that would have caught it on day one. What "og:type" actually does When you paste a URL into Twitter or LinkedIn, the platform fetches the page and reads the Open Graph meta tags to decide what card to show. The most consequential of those tags is og:type . It tells the platform whether the URL is a website, an article, a book, a video, or a profile. Twitter shows different rich cards for article than for website . Facebook surfaces published date and author for article . LinkedIn formats the snippet differently. Search engines also consume og:type as a hint about content classification. The contract is simple: emit it once per page, with the correct value for the page.…