🐛 Leave an alternate that is not a language variant on --base

README.md

@@ -40,9 +40,9 @@ two answers to what had been one question: where the bytes are, and what the
 content is called.
 
 `--canonical` separates them. Urls that _name the page_ —
-`<link rel=canonical>`, its `<meta property="og:url">` twin, and
-`<link rel=alternate>` — are rebased onto it, while navigation, assets and the
-sitemap stay on `--base`:
+`<link rel=canonical>`, its `<meta property="og:url">` twin, and a
+`<link rel=alternate hreflang>` saying it for another language — are rebased
+onto it, while navigation, assets and the sitemap stay on `--base`:
 
 ```
 $ staticalize --site http://localhost:8000 --output dist \
@@ -54,6 +54,9 @@ The build still browses on its own at `--base`, and search engines are told to
 index `--canonical` instead. That is what a preview wants too: readable at its
 own alias, indexed as production.
 
+An `alternate` without `hreflang` is left on `--base`: a feed or an `llms.txt`
+is a separate file, and a file lives where the build is served.
+
 Textual bodies follow `--canonical`, because a document like `llms.txt` is a map
 telling a reader where the docs live rather than a page of the site.
 

downloader.ts

@@ -178,7 +178,17 @@ function names(element: { properties?: Record<string, unknown> }): boolean {
   let rel = element.properties?.rel;
 
   if (Array.isArray(rel)) {
-    return rel.includes("canonical") || rel.includes("alternate");
+    if (rel.includes("canonical")) {
+      return true;
+    }
+
+    // `alternate` covers two unrelated things. With `hreflang` it is this page
+    // in another language, which is a claim about the page. Without it — a
+    // feed, an `llms.txt` — it points at a separate file, which lives wherever
+    // the build is served.
+    if (rel.includes("alternate")) {
+      return Boolean(element.properties?.hrefLang);
+    }
   }
 
   return element.properties?.property === "og:url";

test/staticalize.test.ts

@@ -463,6 +463,7 @@ describe("staticalize", () => {
   <head>
     <link rel="canonical" href="${host}"/>
     <link rel="alternate" href="${host}" hreflang="en"/>
+    <link rel="alternate" type="application/rss+xml" href="${host}feed.xml"/>
     <meta property="og:url" content="${host}"/>
     <meta property="og:image" content="${host}card.png"/>
     <link rel="stylesheet" href="${host}styles.css"/>
@@ -473,6 +474,7 @@ describe("staticalize", () => {
 `),
     )
       .get("/about", (c) => c.html("<h1>About</h1>"))
+      .get("/feed.xml", (c) => c.text("<rss/>"))
       .get("/card.png", (c) => c.text(""))
       .get("/styles.css", (c) => c.text("body {}"))
       .get("/main.js", (c) => c.text("console.log('hi')"))
@@ -499,6 +501,9 @@ describe("staticalize", () => {
     );
 
     // these point at bytes, which live where the build is hosted
+    expect(index).toContain(
+      `<link rel="alternate" type="application/rss+xml" href="https://interactors.netlify.app/feed.xml">`,
+    );
     expect(index).toContain(
       `<link rel="stylesheet" href="https://interactors.netlify.app/styles.css">`,
     );