diff --git a/package.json b/package.json
index 89dfbbb..8a03975 100644
--- a/package.json
+++ b/package.json
@@ -27,7 +27,7 @@
     "check:csp": "node scripts/checkCsp.mjs",
     "play:datasafety": "node scripts/playDataSafety.mjs",
     "beta": "node scripts/beta.mjs",
-    "test": "node --test test/beta.test.mjs test/legal.test.mjs",
+    "test": "node --test test/beta.test.mjs test/legal.test.mjs test/footer.test.mjs",
     "brand:assets": "node scripts/buildBrandAssets.mjs",
     "screens:capture": "node scripts/captureScreens.mjs",
     "csp:hashes": "node scripts/checkCsp.mjs --reset && astro build && node scripts/checkCsp.mjs --write && astro build && node scripts/checkCsp.mjs",
diff --git a/src/components/Footer.astro b/src/components/Footer.astro
index 4a998a7..54a2b9e 100644
--- a/src/components/Footer.astro
+++ b/src/components/Footer.astro
@@ -1,6 +1,7 @@
 ---
 import { renderBrand } from '../lib/brand.mjs';
 import { legal } from '../data/legal.mjs';
+import { footerColumns } from '../data/footer.mjs';
 import platform from '../data/platform.json';
 
 /**
@@ -19,33 +20,9 @@ const brand = renderBrand(Astro);
 
 const year = new Date().getFullYear();
 
-const columns = [
-  {
-    heading: 'Product',
-    links: [
-      { href: '/features/', label: 'Features' },
-      { href: '/architecture/', label: 'Architecture' },
-      { href: '/modules/', label: 'Modules' },
-      { href: '/app/', label: 'Android app' },
-    ],
-  },
-  {
-    heading: 'Documentation',
-    links: [
-      { href: '/docs/', label: 'Getting started' },
-      { href: '/docs/', label: 'Administration' },
-      { href: '/docs/', label: 'Building a module' },
-    ],
-  },
-  {
-    heading: 'Project',
-    links: [
-      { href: brand.giteaOrg, label: 'Source' },
-      { href: brand.discordInvite, label: 'Discord' },
-      { href: '/community/', label: 'Community' },
-    ],
-  },
-];
+// The columns live in src/data/footer.mjs so a test can read them — see the note there,
+// and test/footer.test.mjs. The two Project links come from the mounted brand (§7).
+const columns = footerColumns(brand);
 
 const isExternal = (href: string) => href.startsWith('http');
 ---
diff --git a/src/data/footer.mjs b/src/data/footer.mjs
new file mode 100644
index 0000000..686d982
--- /dev/null
+++ b/src/data/footer.mjs
@@ -0,0 +1,57 @@
+/**
+ * The footer's link columns.
+ *
+ * Data rather than markup, and in `src/data/` beside `legal.mjs` and `collection.mjs`, for
+ * one reason: the links shipped wrong. All three entries under "Documentation" pointed at
+ * `/docs/`, so the column rendered three different labels that went to the same page — and
+ * every check passed, because each href resolved perfectly well. `checkLinks.mjs` asks
+ * whether a link is broken; nothing asked whether a link goes where its label says.
+ *
+ * `test/footer.test.mjs` asks that now, which it can only do because the columns are
+ * importable. That is the whole reason this file exists.
+ *
+ * The two Project links are brand-supplied (§7, D13), so this is a function of the rendered
+ * brand rather than a constant — the mounted `brand.json` decides them, and `/beta` renders
+ * per request, so they cannot be baked at build time.
+ */
+
+/** Documentation sections a footer link may point into, and where each one starts. */
+export const docsEntryPoints = {
+  'getting-started': '/docs/getting-started/requirements/',
+  administration: '/docs/administration/configuration/',
+  modules: '/docs/modules/building-a-module/',
+};
+
+export function footerColumns(brand) {
+  return [
+    {
+      heading: 'Product',
+      links: [
+        { href: '/features/', label: 'Features' },
+        { href: '/architecture/', label: 'Architecture' },
+        { href: '/modules/', label: 'Modules' },
+        { href: '/app/', label: 'Android app' },
+      ],
+    },
+    {
+      // Each of these lands INSIDE the section it names. The docs home — "What is Runic
+      // Gateway?", the first page of Getting started — is the header's `Docs` link, so a
+      // footer entry pointing there as well would be a fourth way to the same page rather
+      // than a way into the section.
+      heading: 'Documentation',
+      links: [
+        { href: docsEntryPoints['getting-started'], label: 'Getting started' },
+        { href: docsEntryPoints.administration, label: 'Administration' },
+        { href: docsEntryPoints.modules, label: 'Building a module' },
+      ],
+    },
+    {
+      heading: 'Project',
+      links: [
+        { href: brand.giteaOrg, label: 'Source' },
+        { href: brand.discordInvite, label: 'Discord' },
+        { href: '/community/', label: 'Community' },
+      ],
+    },
+  ];
+}
diff --git a/test/footer.test.mjs b/test/footer.test.mjs
new file mode 100644
index 0000000..0cbc738
--- /dev/null
+++ b/test/footer.test.mjs
@@ -0,0 +1,97 @@
+/**
+ * The footer's links, tested where a mistake is invisible to every other check.
+ *
+ * ---------------------------------------------------------------------------------------
+ * WHY THIS FILE EXISTS
+ * ---------------------------------------------------------------------------------------
+ * The footer shipped with all three "Documentation" links pointing at `/docs/`. Three
+ * labels — Getting started, Administration, Building a module — and one destination. It
+ * reached production and stayed there through eleven checks and two test suites, because
+ * none of them could see it:
+ *
+ *   - `checkLinks.mjs` resolves every internal link against the build. `/docs/` resolves.
+ *     Three links to a page that exists are three valid links.
+ *   - `checkSidebar.mjs` compares the docs tree to the planned tree. The footer is not the
+ *     sidebar and was never in scope.
+ *   - `checkA11y.mjs` checks structure. Three correctly-marked-up links are correct markup.
+ *
+ * The bug is not a broken link. It is a link that goes somewhere other than where its label
+ * says, which is the one property nothing was asserting. So that is what this file asserts,
+ * and the reason `src/data/footer.mjs` exists at all — a column list inside an `.astro`
+ * component cannot be imported by a test.
+ */
+
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+
+import { footerColumns, docsEntryPoints } from '../src/data/footer.mjs';
+
+/** A stand-in for the rendered brand; only the two Project links read it. */
+const brand = {
+  giteaOrg: 'https://gitea.example.com/Org',
+  discordInvite: 'https://discord.gg/example',
+};
+
+const columns = footerColumns(brand);
+const documentation = columns.find((c) => c.heading === 'Documentation');
+
+test('every link in a column has its own destination', () => {
+  for (const column of columns) {
+    const hrefs = column.links.map((l) => l.href);
+    assert.equal(
+      new Set(hrefs).size,
+      hrefs.length,
+      `the ${column.heading} column has two links pointing at the same page: ${hrefs.join(', ')}`,
+    );
+  }
+});
+
+test('no two columns offer the same destination twice', () => {
+  const all = columns.flatMap((c) => c.links.map((l) => l.href));
+  assert.equal(new Set(all).size, all.length, `a footer destination is repeated: ${all.join(', ')}`);
+});
+
+test('each documentation link lands inside the section its label names', () => {
+  // The exact failure that shipped: `/docs/` under all three labels satisfies "starts with
+  // /docs/" but names no section, so the prefixes below are section prefixes, not `/docs/`.
+  const expected = [
+    ['Getting started', '/docs/getting-started/'],
+    ['Administration', '/docs/administration/'],
+    ['Building a module', '/docs/modules/'],
+  ];
+
+  for (const [label, prefix] of expected) {
+    const link = documentation.links.find((l) => l.label === label);
+    assert.ok(link, `the Documentation column no longer has a "${label}" link`);
+    assert.ok(
+      link.href.startsWith(prefix),
+      `"${label}" points at ${link.href}, which is not inside ${prefix}`,
+    );
+  }
+});
+
+test('no documentation link is the docs home, which the header already carries', () => {
+  for (const link of documentation.links) {
+    assert.notEqual(
+      link.href,
+      '/docs/',
+      `"${link.label}" points at the docs home; the header's Docs link is that page`,
+    );
+  }
+});
+
+test('every documentation entry point is a directory URL', () => {
+  // Astro builds these as directories with an index.html; a missing trailing slash costs a
+  // redirect on every click and reads as a broken path in the status bar.
+  for (const [section, href] of Object.entries(docsEntryPoints)) {
+    assert.ok(href.endsWith('/'), `the ${section} entry point (${href}) needs a trailing slash`);
+    assert.ok(href.startsWith('/docs/'), `the ${section} entry point (${href}) is not under /docs/`);
+  }
+});
+
+test('the brand supplies the two Project links rather than the code', () => {
+  const project = columns.find((c) => c.heading === 'Project');
+  const hrefs = project.links.map((l) => l.href);
+  assert.ok(hrefs.includes(brand.giteaOrg), 'the Source link no longer reads brand.giteaOrg');
+  assert.ok(hrefs.includes(brand.discordInvite), 'the Discord link no longer reads brand.discordInvite');
+});