From c3145580846d1a2cf2da048c3d105e63d825eb33 Mon Sep 17 00:00:00 2001
From: David Dal Busco <david.dalbusco@dfinity.org>
Date: Tue, 7 Oct 2025 17:34:14 +0200
Subject: [PATCH 1/2] feat(frontend): prerender canonical URL for subpages

Signed-off-by: David Dal Busco <david.dalbusco@dfinity.org>
---
 frontend/package.json          |  3 ++-
 frontend/scripts/build.seo.mjs | 38 ++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 1 deletion(-)
 create mode 100644 frontend/scripts/build.seo.mjs

diff --git a/frontend/package.json b/frontend/package.json
index ab30bee186d..cbb5e8960db 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -5,8 +5,9 @@
   "license": "SEE LICENSE IN LICENSE.md",
   "scripts": {
     "build:csp": "node scripts/build.csp.mjs",
+    "build:seo": "node scripts/build.seo.mjs",
     "build:preload": "node scripts/build.preload.mjs",
-    "build:post-process": "npm run build:csp",
+    "build:post-process": "npm run build:seo && npm run build:csp",
     "i18n": "node scripts/i18n.types.js && prettier --write ./src/lib/types/i18n.d.ts",
     "dev": "npm run i18n && vite dev",
     "build": "npm run i18n && tsc --noEmit && vite build && npm run build:post-process",
diff --git a/frontend/scripts/build.seo.mjs b/frontend/scripts/build.seo.mjs
new file mode 100644
index 00000000000..e376b8e8c24
--- /dev/null
+++ b/frontend/scripts/build.seo.mjs
@@ -0,0 +1,38 @@
+import { readFileSync, writeFileSync } from "node:fs";
+import { dirname, join, relative } from "node:path";
+import { findHtmlFiles } from "./build.utils.mjs";
+
+const OUTPUT_DIR = join(process.cwd(), "public");
+const SITE_ROOT_CANONICAL = "https://nns.ic0.app/";
+
+const updateCanonical = (htmlFilePath) => {
+  // 1. We determine the route based on the output
+  const routePath = dirname(relative(OUTPUT_DIR, htmlFilePath));
+
+  // 2. Build the effective canonical route
+  const canonicalPath = `${SITE_ROOT_CANONICAL}${routePath}/`;
+
+  // 2. Read content
+  let html = readFileSync(htmlFilePath, "utf-8");
+
+  // 3. Update canonical
+  html = html.replace(
+    `<link href="${SITE_ROOT_CANONICAL}" rel="canonical" />`,
+    `<link href="${canonicalPath}" rel="canonical" />`
+  );
+
+  // 4. Update og:url to reflect the canonical
+  html = html.replace(
+    `<meta content="${SITE_ROOT_CANONICAL}" property="og:url" />`,
+    `<meta content="${canonicalPath}" property="og:url" />`
+  );
+
+  // 5. Save the content with the updated canonical URL
+  writeFileSync(htmlFilePath, html);
+};
+
+// Do not replace canonical for root and 404 pages
+const filterSubPages = (htmlFile) => dirname(htmlFile) !== OUTPUT_DIR;
+
+const htmlFiles = findHtmlFiles().filter(filterSubPages);
+htmlFiles.forEach((htmlFile) => updateCanonical(htmlFile));

From 60706d399e919011ba5473e81107d557fc792914 Mon Sep 17 00:00:00 2001
From: David Dal Busco <david.dalbusco@dfinity.org>
Date: Tue, 7 Oct 2025 20:50:39 +0200
Subject: [PATCH 2/2] Update frontend/scripts/build.seo.mjs

Co-authored-by: Yusef Habib <yusef.fernandez@dfinity.org>
---
 frontend/scripts/build.seo.mjs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/frontend/scripts/build.seo.mjs b/frontend/scripts/build.seo.mjs
index e376b8e8c24..657a17df747 100644
--- a/frontend/scripts/build.seo.mjs
+++ b/frontend/scripts/build.seo.mjs
@@ -35,4 +35,4 @@ const updateCanonical = (htmlFilePath) => {
 const filterSubPages = (htmlFile) => dirname(htmlFile) !== OUTPUT_DIR;
 
 const htmlFiles = findHtmlFiles().filter(filterSubPages);
-htmlFiles.forEach((htmlFile) => updateCanonical(htmlFile));
+htmlFiles.forEach(updateCanonical);