docs: add an RSS feed to the blog at /blog/rss.xml

Closes #6522. The route handler renders the non-draft posts newest-first, the blog layout advertises the feed for autodiscovery, and the blog index links it next to the post count.

Author: colinhacks

packages/docs/app/blog/layout.tsx

@@ -1,8 +1,16 @@
 import { baseOptions } from "@/app/layout.config";
 import { GitHubStarPill } from "@/components/github-star-pill";
 import { HomeLayout } from "fumadocs-ui/layouts/home";
+import type { Metadata } from "next";
 import type { ReactNode } from "react";
 
+// feed autodiscovery for the blog index and every post
+export const metadata: Metadata = {
+  alternates: {
+    types: { "application/rss+xml": [{ url: "https://zod.dev/blog/rss.xml", title: "Zod Blog" }] },
+  },
+};
+
 // the star pill takes the navbar's top-right slot; `on: "nav"` keeps it in the bar itself on mobile rather than in the collapsed menu
 export default function BlogLayout({ children }: { children: ReactNode }) {
   return (

packages/docs/app/blog/page.tsx

@@ -1,5 +1,5 @@
-import { blog, formatDate } from "@/loaders/source";
 import { InlineCodeTitle } from "@/components/inline-code-title";
+import { blog, formatDate } from "@/loaders/source";
 import Link from "next/link";
 
 export const revalidate = false;
@@ -14,7 +14,12 @@ export default function BlogIndexPage() {
       <div className="mx-auto max-w-4xl">
         <h1 className="flex items-baseline justify-between text-[11px] font-medium uppercase tracking-[0.18em] text-fd-muted-foreground">
           Blog
-          <span className="tabular-nums">{posts.length} posts</span>
+          <span className="flex items-baseline gap-4">
+            <a href="/blog/rss.xml" className="hover:text-[var(--ui-color)] transition-colors">
+              RSS
+            </a>
+            <span className="tabular-nums">{posts.length} posts</span>
+          </span>
         </h1>
         <ul>
           {posts.map((post) => {

packages/docs/app/blog/rss.xml/route.ts

@@ -0,0 +1,44 @@
+import { stripBackticks } from "@/components/inline-code-title";
+import { blog } from "@/loaders/source";
+
+// cached forever
+export const revalidate = false;
+
+const escapeXml = (text: string) => text.replaceAll("&", "&amp;").replaceAll("<", "&lt;").replaceAll(">", "&gt;");
+
+export function GET() {
+  const posts = (blog.getPages() as any[])
+    .filter((post) => !post.data?.draft)
+    .sort((a, b) => new Date(b.data?.date ?? 0).getTime() - new Date(a.data?.date ?? 0).getTime());
+
+  const items = posts.map((post) => {
+    const url = `https://zod.dev${post.url}`;
+    const title = stripBackticks((post.data?.title as string | undefined) ?? post.slugs.join("/"));
+    const description = (post.data?.description as string | undefined) ?? "";
+    const pubDate = new Date(post.data?.date ?? 0).toUTCString();
+    return `    <item>
+      <title>${escapeXml(title)}</title>
+      <link>${url}</link>
+      <guid>${url}</guid>
+      <pubDate>${pubDate}</pubDate>
+      <description>${escapeXml(description)}</description>
+    </item>`;
+  });
+
+  const xml = `<?xml version="1.0" encoding="UTF-8"?>
+<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
+  <channel>
+    <title>Zod Blog</title>
+    <link>https://zod.dev/blog</link>
+    <description>Release announcements and engineering deep dives from Zod.</description>
+    <language>en-us</language>
+    <atom:link href="https://zod.dev/blog/rss.xml" rel="self" type="application/rss+xml"/>
+${items.join("\n")}
+  </channel>
+</rss>
+`;
+
+  return new Response(xml, {
+    headers: { "Content-Type": "application/rss+xml; charset=utf-8" },
+  });
+}