fix(converters): stop blog footer turning the last body line into a heading

.changeset/blog-converter-setext-heading.md

@@ -0,0 +1,7 @@
+---
+"@dualmark/converters": patch
+---
+
+Fix the blog converter turning a post's last body line into a heading.
+
+The footer was concatenated directly onto the body with no blank line, so the output ended with `last body line\n---`. CommonMark parses a line of text immediately followed by `---` as a setext H2, which turned the final line of every blog post body into a heading and dropped the intended horizontal rule before the footer links. The body and footer are now separated by a blank line so the `---` is a thematic break.

packages/converters/src/blog.ts

@@ -52,6 +52,10 @@ export function blogConverter(
       footer.push(`- [All articles](${config.siteUrl}${basePath})`);
     }
     if (config.brandFooter) footer.push("", config.brandFooter);
-    return normalizeUnicode(base + footer.join("\n"));
+    // Separate the body from the footer with a blank line. `base` ends with the
+    // body's last line (no trailing newline) and `footer` starts with "---";
+    // without the blank line CommonMark parses "lastline\n---" as a setext H2,
+    // turning the final body line into a heading and swallowing the rule.
+    return normalizeUnicode(base + "\n" + footer.join("\n"));
   };
 }

packages/converters/test/converters.test.ts

@@ -78,6 +78,18 @@ describe("blogConverter", () => {
     });
     expect(out).toContain("## About Acme");
   });
+
+  it("separates the body from the footer so the last line is not a setext heading", () => {
+    const out = convert({
+      id: "p",
+      data: { title: "T", publishedDate: new Date("2026-01-01T00:00:00Z") },
+      body: "Final body line.",
+    });
+    // "Final body line.\n---" would render as a setext H2 in CommonMark,
+    // turning the last body line into a heading and dropping the rule.
+    expect(out).toContain("Final body line.\n\n---");
+    expect(out).not.toContain("Final body line.\n---\n");
+  });
 });
 
 describe("caseStudyConverter", () => {