Feature: OG Social media cards

Not Original Gangsta, but ObjectGraph

Reason: images were showing on LinkedIn, but small.

blogex/test/blogex/post_test.exs

@@ -58,6 +58,20 @@ defmodule Blogex.PostTest do
 
       assert post.published == false
     end
+
+    test "preserves image from frontmatter" do
+      attrs = Map.put(valid_attrs(), :image, "/images/cover.png")
+
+      post = Post.build("x/2026/01-01-x.md", attrs, "<p>x</p>")
+
+      assert post.image == "/images/cover.png"
+    end
+
+    test "defaults image to nil when not in frontmatter" do
+      post = Post.build("x/2026/01-01-x.md", valid_attrs(), "<p>x</p>")
+
+      assert post.image == nil
+    end
   end
 
   defp valid_attrs do

blogex/test/blogex/seo_test.exs

@@ -6,6 +6,8 @@ defmodule Blogex.SEOTest do
 
   defmodule StubBlog do
     def base_path, do: "/blog/eng"
+    def title, do: "Engineering Blog"
+    def description, do: "Our engineering insights"
   end
 
   @base_url "https://example.com"
@@ -38,6 +40,63 @@ defmodule Blogex.SEOTest do
       assert meta.article_published_time == "2026-06-15"
       assert meta.article_tags == ["a", "b"]
     end
+
+    test "includes og_image when post has an image" do
+      post = build(image: "/images/cover.png")
+
+      meta = SEO.meta_tags(post, @base_url, StubBlog)
+
+      assert meta.og_image == "https://example.com/images/cover.png"
+    end
+
+    test "og_image is nil when post has no image" do
+      post = build()
+
+      meta = SEO.meta_tags(post, @base_url, StubBlog)
+
+      assert meta.og_image == nil
+    end
+
+    test "og_image uses absolute URL with base_url prefix" do
+      post = build(image: "/assets/post-hero.jpg")
+
+      meta = SEO.meta_tags(post, "https://myapp.dev", StubBlog)
+
+      assert meta.og_image == "https://myapp.dev/assets/post-hero.jpg"
+    end
+  end
+
+  describe "meta_tags_for_blog/2" do
+    test "returns website type" do
+      meta = SEO.meta_tags_for_blog(StubBlog, @base_url)
+
+      assert meta.og_type == "website"
+    end
+
+    test "includes blog title and description" do
+      meta = SEO.meta_tags_for_blog(StubBlog, @base_url)
+
+      assert meta.og_title == "Engineering Blog"
+      assert meta.og_description == "Our engineering insights"
+    end
+
+    test "has no og_image for blog listing" do
+      meta = SEO.meta_tags_for_blog(StubBlog, @base_url)
+
+      assert meta.og_image == nil
+    end
+
+    test "builds correct blog URL" do
+      meta = SEO.meta_tags_for_blog(StubBlog, @base_url)
+
+      assert meta.og_url == "https://example.com/blog/eng"
+    end
+
+    test "uses summary twitter card for blog listing" do
+      meta = SEO.meta_tags_for_blog(StubBlog, @base_url)
+
+      assert meta.twitter_card == "summary"
+    end
   end
 
   describe "sitemap/2" do