Social Embeds

When a post is shared on social media or chat apps, those services render a preview card from the OpenGraph and Twitter Card <meta> tags in the post’s HTML <head>. Lamb emits these automatically for individual posts (the /status/<id> and slugged-post pages).

How the card image is chosen

Lamb picks the embed image (og:image / twitter:image) in this order, most specific first:

  1. The first image in the post. If the post body embeds an image, that image becomes the card image and the Twitter card is upgraded to summary_large_image (a large, image-led preview). So sharing a photo or screenshot post previews that image.
  2. A site-wide default you provide. If the post has no image, Lamb looks for an og-image.* file in the web root (next to index.php) and uses it.
  3. The built-in Lamb card. If you haven’t provided one, the shipped og-image-lamb.webp is used.

Setting a site-wide card

Drop an image named og-image into the src/ directory (the web root), using any of these extensions:

png, jpg, jpeg, webp, gif

For example, src/og-image.png. No configuration is needed — the file is picked up by convention, exactly like the feed icon and logo. A 1200×630 image is the conventional size for a social card.

If your blog is mostly short text posts without images, setting a site-wide card is worthwhile: it gives every shared link a consistent, branded preview — your blog’s identity — rather than the generic built-in card. Image posts still preview their own first image automatically.

Lamb reads the image’s real dimensions and type for the og:image:width, og:image:height, and og:image:type tags when the file is readable, so you don’t need to declare them anywhere.

  • Media — uploading images into posts (these become the card image automatically)
  • Feeds — the related favicon.png / logo.png web-root convention for feed readers
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