feat(blog): add the blog index, post pages, RSS and content sitemap

The rendering split is dictated by CI building with no database.

/blog, /blog/rss.xml and /content-sitemap.xml have no dynamic params, so
Next prerenders them at build time and the build fails on a missing
Payload secret — caught here, not on staging. They are force-dynamic
instead: one indexed query against Postgres on the same Docker network,
and a newly published post appears immediately rather than waiting on a
revalidation. /blog/[slug] keeps ISR, because with no
generateStaticParams there is nothing to prerender; it is generated on
first request and cached, which is exactly what the collection's
afterChange hook exists to invalidate.

RichText takes `converters`, not `blocks`, in Payload 3.88, and the
default converters must be spread or every paragraph and heading loses
its renderer and the body comes out empty.

BlogPosting references the Person and Organization by @id rather than
repeating them, so every post and the About page resolve to one author
entity instead of declaring several people with the same name.

/sitemap.xml is proxied from FastAPI, which knows nothing about Payload,
so the Next-owned URLs get their own sitemap and robots.txt lists both.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017YmbBhr8s7GusjDE12hrZM

nextjs-app/app/(frontend)/blog/Blog.module.css

@@ -0,0 +1,76 @@
+.page {
+  max-width: 42rem;
+  margin: 0 auto;
+  padding: 2.5rem 1.25rem 4rem;
+}
+
+.header { margin-bottom: 2.5rem; }
+
+.kicker {
+  font-family: var(--font-ui);
+  font-size: 0.75rem;
+  font-weight: 600;
+  text-transform: uppercase;
+  letter-spacing: 0.06em;
+  color: var(--brand);
+  margin: 0 0 0.35rem;
+}
+
+.heading {
+  font-family: var(--font-display);
+  font-size: clamp(1.5rem, 4vw, 2rem);
+  font-weight: 700;
+  line-height: 1.2;
+  color: var(--text-primary);
+  margin: 0 0 0.75rem;
+}
+
+.standfirst {
+  font-family: var(--font-ui);
+  font-size: 1.05rem;
+  line-height: 1.65;
+  color: var(--text-secondary);
+  margin: 0;
+}
+
+.list { list-style: none; padding: 0; margin: 0; }
+
+.item {
+  padding: 1.5rem 0;
+  border-top: 1px solid var(--border);
+}
+
+.date {
+  font-family: var(--font-ui);
+  font-size: 0.8rem;
+  color: var(--text-muted);
+  /* Inter's tabular numerals keep a column of dates aligned. */
+  font-variant-numeric: tabular-nums;
+}
+
+.itemTitle {
+  font-family: var(--font-display);
+  font-size: 1.25rem;
+  font-weight: 600;
+  line-height: 1.3;
+  margin: 0.35rem 0 0.5rem;
+}
+
+.itemLink { color: var(--text-primary); text-decoration: none; }
+.itemLink:hover { color: var(--brand); }
+
+.excerpt {
+  font-family: var(--font-ui);
+  font-size: 0.95rem;
+  line-height: 1.65;
+  color: var(--text-secondary);
+  margin: 0;
+}
+
+.empty {
+  font-family: var(--font-ui);
+  color: var(--text-muted);
+}
+
+.link { color: var(--brand); font-weight: 600; }
+.link:hover { color: var(--brand-strong); }

nextjs-app/app/(frontend)/blog/[slug]/Post.module.css

@@ -0,0 +1,87 @@
+.page {
+  max-width: 42rem;
+  margin: 0 auto;
+  padding: 2.5rem 1.25rem 4rem;
+}
+
+.crumb {
+  font-family: var(--font-ui);
+  font-size: 0.85rem;
+  margin-bottom: 1.25rem;
+}
+
+.heading {
+  font-family: var(--font-display);
+  font-size: clamp(1.6rem, 5vw, 2.25rem);
+  font-weight: 700;
+  line-height: 1.2;
+  color: var(--text-primary);
+  margin: 0 0 0.75rem;
+}
+
+.byline {
+  font-family: var(--font-ui);
+  font-size: 0.9rem;
+  color: var(--text-muted);
+  margin: 0 0 2rem;
+}
+
+.hero {
+  width: 100%;
+  height: auto;
+  border-radius: 10px;
+  border: 1px solid var(--border);
+  margin-bottom: 2rem;
+}
+
+/* Rich-text output: the editor emits plain elements, so these are styled by
+   descendant selector rather than by class. */
+.prose p {
+  font-family: var(--font-ui);
+  font-size: 1rem;
+  line-height: 1.7;
+  color: var(--text-secondary);
+  margin: 0 0 1.1rem;
+}
+
+.prose h2 {
+  font-family: var(--font-display);
+  font-size: 1.25rem;
+  font-weight: 600;
+  color: var(--text-primary);
+  margin: 2.25rem 0 0.75rem;
+}
+
+.prose h3 {
+  font-family: var(--font-display);
+  font-size: 1.05rem;
+  font-weight: 600;
+  color: var(--text-primary);
+  margin: 1.75rem 0 0.6rem;
+}
+
+.prose ul,
+.prose ol {
+  font-family: var(--font-ui);
+  font-size: 1rem;
+  line-height: 1.7;
+  color: var(--text-secondary);
+  padding-left: 1.35rem;
+  margin: 0 0 1.1rem;
+}
+
+.prose li { margin-bottom: 0.4rem; }
+
+.prose a { color: var(--brand); font-weight: 500; }
+.prose a:hover { color: var(--brand-strong); }
+
+.prose blockquote {
+  border-left: 3px solid var(--border-strong);
+  padding-left: 1rem;
+  margin: 1.5rem 0;
+  color: var(--text-muted);
+  font-style: italic;
+}
+
+.link { color: var(--brand); font-weight: 600; }
+.link:hover { color: var(--brand-strong); }

nextjs-app/app/(frontend)/blog/[slug]/page.tsx

@@ -0,0 +1,164 @@
+import type { Metadata } from 'next';
+import Link from 'next/link';
+import { notFound } from 'next/navigation';
+import { RichText } from '@payloadcms/richtext-lexical/react';
+import type { JSXConvertersFunction } from '@payloadcms/richtext-lexical/react';
+import { getCachedPayload } from '@/lib/payload';
+import { absoluteUrl } from '@/lib/site';
+import {
+  blogPostingJsonLd,
+  breadcrumbJsonLd,
+  personJsonLd,
+  organizationJsonLd,
+} from '@/lib/jsonld';
+import { CalloutBlock } from '@/components/blog/CalloutBlock';
+import styles from './Post.module.css';
+
+/*
+ * ISR. Unlike the index, this route has a dynamic param and no
+ * generateStaticParams, so there is nothing for the build to prerender: each
+ * post is generated on first request and cached until the collection's
+ * afterChange hook revalidates it. That hook is what makes an edit to an
+ * already-published post appear immediately.
+ */
+export const revalidate = 3600;
+
+interface HeroImage {
+  url?: string | null;
+  alt?: string | null;
+  width?: number | null;
+  height?: number | null;
+}
+
+/**
+ * Spreads the default converters and adds the one custom block.
+ *
+ * Without the spread, every default node type — paragraphs, headings, links —
+ * loses its renderer and the post body comes out empty.
+ */
+const calloutConverters: JSXConvertersFunction = ({ defaultConverters }) => ({
+  ...defaultConverters,
+  blocks: {
+    // Annotated because the generic block converter cannot infer a custom
+    // block's field shape; String() guards the values regardless.
+    callout: ({ node }: { node: { fields: Record<string, unknown> } }) => (
+      <CalloutBlock
+        tone={String(node.fields.tone ?? 'caveat')}
+        body={String(node.fields.body ?? '')}
+      />
+    ),
+  },
+});
+
+async function findPost(slug: string) {
+  const payload = await getCachedPayload();
+  const { docs } = await payload.find({
+    collection: 'posts',
+    where: { slug: { equals: slug }, _status: { equals: 'published' } },
+    limit: 1,
+    depth: 1,
+  });
+  return docs[0] ?? null;
+}
+
+function summarise(post: Record<string, unknown>) {
+  return {
+    title: String(post.title),
+    slug: String(post.slug),
+    excerpt: String(post.excerpt),
+    publishedAt: String(post.publishedAt),
+  };
+}
+
+export async function generateMetadata(
+  { params }: { params: Promise<{ slug: string }> },
+): Promise<Metadata> {
+  const { slug } = await params;
+  const post = await findPost(slug);
+  if (!post) return { title: 'Not found' };
+
+  const hero = post.heroImage as HeroImage | null | undefined;
+
+  return {
+    title: String(post.title),
+    description: String(post.excerpt),
+    alternates: { canonical: absoluteUrl(`/blog/${post.slug}`) },
+    openGraph: {
+      type: 'article',
+      title: String(post.title),
+      description: String(post.excerpt),
+      url: absoluteUrl(`/blog/${post.slug}`),
+      publishedTime: String(post.publishedAt),
+      // A post with a hero image shares that; one without falls through to the
+      // generated share card at app/opengraph-image.tsx.
+      ...(hero?.url ? { images: [{ url: hero.url }] } : {}),
+    },
+  };
+}
+
+export default async function PostPage(
+  { params }: { params: Promise<{ slug: string }> },
+) {
+  const { slug } = await params;
+  const post = await findPost(slug);
+  if (!post) notFound();
+
+  const summary = summarise(post as Record<string, unknown>);
+  const hero = post.heroImage as HeroImage | null | undefined;
+
+  const jsonLd = {
+    '@context': 'https://schema.org',
+    '@graph': [
+      blogPostingJsonLd(summary),
+      breadcrumbJsonLd(summary),
+      personJsonLd(),
+      organizationJsonLd(),
+    ],
+  };
+
+  return (
+    <article className={styles.page}>
+      <script
+        type="application/ld+json"
+        dangerouslySetInnerHTML={{ __html: JSON.stringify(jsonLd) }}
+      />
+
+      <nav className={styles.crumb}>
+        <Link href="/blog" className={styles.link}>Blog</Link>
+      </nav>
+
+      <h1 className={styles.heading}>{summary.title}</h1>
+
+      <p className={styles.byline}>
+        By <Link href="/about" className={styles.link}>Tudor</Link>
+        {' · '}
+        <time dateTime={summary.publishedAt}>
+          {new Date(summary.publishedAt).toLocaleDateString('en-GB', {
+            day: 'numeric',
+            month: 'long',
+            year: 'numeric',
+          })}
+        </time>
+      </p>
+
+      {/*
+        A plain <img>, not next/image: Payload already generated the sized
+        derivatives on upload (Media's imageSizes), so routing it through the
+        optimizer would resize an image that is already the right size.
+      */}
+      {hero?.url && (
+        <img
+          className={styles.hero}
+          src={hero.url}
+          alt={hero.alt ?? ''}
+          width={hero.width ?? undefined}
+          height={hero.height ?? undefined}
+        />
+      )}
+
+      <div className={styles.prose}>
+        <RichText data={post.content as never} converters={calloutConverters} />
+      </div>
+    </article>
+  );
+}

nextjs-app/app/(frontend)/blog/page.tsx

@@ -0,0 +1,76 @@
+import type { Metadata } from 'next';
+import Link from 'next/link';
+import { getCachedPayload } from '@/lib/payload';
+import { absoluteUrl } from '@/lib/site';
+import styles from './Blog.module.css';
+
+/*
+ * Dynamic, not ISR.
+ *
+ * This route has no dynamic params, so Next prerenders it at build time — and
+ * CI builds the image with no database reachable, which fails the build. It is
+ * a single indexed query against Postgres on the same Docker network, so
+ * rendering per request is cheap, and it means a newly published post appears
+ * here immediately rather than waiting on a revalidation.
+ */
+export const dynamic = 'force-dynamic';
+
+export const metadata: Metadata = {
+  title: 'Blog',
+  description:
+    'Notes on what school performance data shows, and what it does not.',
+  alternates: { canonical: absoluteUrl('/blog') },
+};
+
+function formatDate(value: string) {
+  return new Date(value).toLocaleDateString('en-GB', {
+    day: 'numeric',
+    month: 'long',
+    year: 'numeric',
+  });
+}
+
+export default async function BlogIndexPage() {
+  const payload = await getCachedPayload();
+  const { docs } = await payload.find({
+    collection: 'posts',
+    where: { _status: { equals: 'published' } },
+    sort: '-publishedAt',
+    limit: 50,
+    depth: 0,
+  });
+
+  return (
+    <div className={styles.page}>
+      <header className={styles.header}>
+        <p className={styles.kicker}>Blog</p>
+        <h1 className={styles.heading}>Notes on the numbers</h1>
+        <p className={styles.standfirst}>
+          What school performance data shows, what it doesn&apos;t, and how to
+          read it without being misled. Written by{' '}
+          <Link href="/about" className={styles.link}>Tudor</Link>.
+        </p>
+      </header>
+
+      {docs.length === 0 ? (
+        <p className={styles.empty}>No posts yet.</p>
+      ) : (
+        <ul className={styles.list}>
+          {docs.map((post) => (
+            <li key={post.id} className={styles.item}>
+              <time className={styles.date} dateTime={String(post.publishedAt)}>
+                {formatDate(String(post.publishedAt))}
+              </time>
+              <h2 className={styles.itemTitle}>
+                <Link href={`/blog/${post.slug}`} className={styles.itemLink}>
+                  {post.title}
+                </Link>
+              </h2>
+              <p className={styles.excerpt}>{post.excerpt}</p>
+            </li>
+          ))}
+        </ul>
+      )}
+    </div>
+  );
+}

nextjs-app/app/(frontend)/blog/rss.xml/route.ts

@@ -0,0 +1,52 @@
+import { getCachedPayload } from '@/lib/payload';
+import { absoluteUrl } from '@/lib/site';
+
+/*
+ * Dynamic, not ISR.
+ *
+ * This route has no dynamic params, so Next prerenders it at build time — and
+ * CI builds the image with no database reachable, which fails the build. It is
+ * a single indexed query against Postgres on the same Docker network, so
+ * rendering per request is cheap, and it means a newly published post appears
+ * here immediately rather than waiting on a revalidation.
+ */
+export const dynamic = 'force-dynamic';
+
+function escapeXml(value: string): string {
+  return value.replace(/[<>&'"]/g, (char) =>
+    ({ '<': '&lt;', '>': '&gt;', '&': '&amp;', "'": '&apos;', '"': '&quot;' }[char]!));
+}
+
+export async function GET() {
+  const payload = await getCachedPayload();
+  const { docs } = await payload.find({
+    collection: 'posts',
+    where: { _status: { equals: 'published' } },
+    sort: '-publishedAt',
+    limit: 50,
+    depth: 0,
+  });
+
+  const items = docs.map((post) => `
+    <item>
+      <title>${escapeXml(String(post.title))}</title>
+      <link>${absoluteUrl(`/blog/${post.slug}`)}</link>
+      <guid isPermaLink="true">${absoluteUrl(`/blog/${post.slug}`)}</guid>
+      <description>${escapeXml(String(post.excerpt))}</description>
+      <pubDate>${new Date(String(post.publishedAt)).toUTCString()}</pubDate>
+    </item>`).join('');
+
+  const xml = `<?xml version="1.0" encoding="UTF-8"?>
+<rss version="2.0">
+  <channel>
+    <title>schoolcompare blog</title>
+    <link>${absoluteUrl('/blog')}</link>
+    <description>What school performance data shows, and what it does not.</description>
+    <language>en-GB</language>${items}
+  </channel>
+</rss>`;
+
+  return new Response(xml, {
+    headers: { 'Content-Type': 'application/rss+xml; charset=utf-8' },
+  });
+}

nextjs-app/app/(frontend)/content-sitemap.xml/route.ts

@@ -0,0 +1,52 @@
+/*
+ * A second sitemap for the URLs Next owns.
+ *
+ * /sitemap.xml is proxied from FastAPI (app/(frontend)/sitemap.xml), which
+ * knows nothing about Payload — the backend and frontend ship as separate
+ * images. Rather than teach it, the Next-owned URLs get their own sitemap and
+ * robots.txt lists both.
+ */
+import { getCachedPayload } from '@/lib/payload';
+import { absoluteUrl } from '@/lib/site';
+
+/*
+ * Dynamic, not ISR.
+ *
+ * This route has no dynamic params, so Next prerenders it at build time — and
+ * CI builds the image with no database reachable, which fails the build. It is
+ * a single indexed query against Postgres on the same Docker network, so
+ * rendering per request is cheap, and it means a newly published post appears
+ * here immediately rather than waiting on a revalidation.
+ */
+export const dynamic = 'force-dynamic';
+
+export async function GET() {
+  const payload = await getCachedPayload();
+  const { docs } = await payload.find({
+    collection: 'posts',
+    where: { _status: { equals: 'published' } },
+    sort: '-publishedAt',
+    limit: 500,
+    depth: 0,
+  });
+
+  const urls: Array<{ loc: string; lastmod: string | null }> = [
+    { loc: absoluteUrl('/about'), lastmod: null },
+    { loc: absoluteUrl('/blog'), lastmod: null },
+    ...docs.map((post) => ({
+      loc: absoluteUrl(`/blog/${post.slug}`),
+      lastmod: new Date(String(post.updatedAt ?? post.publishedAt)).toISOString(),
+    })),
+  ];
+
+  const xml = `<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+${urls.map(({ loc, lastmod }) =>
+  `  <url><loc>${loc}</loc>${lastmod ? `<lastmod>${lastmod}</lastmod>` : ''}</url>`,
+).join('\n')}
+</urlset>`;
+
+  return new Response(xml, {
+    headers: { 'Content-Type': 'application/xml; charset=utf-8' },
+  });
+}

nextjs-app/app/robots.ts

@@ -17,6 +17,9 @@ export default function robots(): MetadataRoute.Robots {
         disallow: ['/api/', '/_next/', '/admin/', '/cms-api/'],
       },
     ],
-    sitemap: absoluteUrl('/sitemap.xml'),
+    // Two sitemaps: /sitemap.xml is proxied from FastAPI and carries the
+    // school corpus; /content-sitemap.xml is Next-owned and carries /about
+    // and the blog. The backend knows nothing about Payload.
+    sitemap: [absoluteUrl('/sitemap.xml'), absoluteUrl('/content-sitemap.xml')],
   };
 }