Add middleware to inject topic metadata for Starlight search functionality

Author: khalidabuhakmeh

astro.config.mjs

@@ -37,6 +37,7 @@ export default defineConfig({
   integrations: [
     starlight({
       customCss: ["./src/styles/custom.css"],
+      routeMiddleware: ["./src/plugins/search-topic-middleware.ts"],
       plugins: [
         starlightLlmsTxt(),
         starlightHeadingBadges(),

src/plugins/search-topic-middleware.ts

@@ -0,0 +1,25 @@
+import { defineRouteMiddleware } from "@astrojs/starlight/route-data";
+
+const topics = [
+  { key: "/bff/", value: "Backend For Frontend Security Library" },
+  { key: "/accesstokenmanagement/", value: "Access Token Management" },
+  { key: "/general/", value: "General" },
+  { key: "/identitymodel/", value: "Identity Model" },
+  {
+    key: "/identitymodel-oidcclient/",
+    value: "Identity Model - OpenID Connect Client",
+  },
+  { key: "/identityserver/", value: "IdentityServer" },
+];
+
+export const onRequest = defineRouteMiddleware((context) => {
+  const { starlightRoute } = context.locals;
+  const path = starlightRoute.entry.filePath;
+
+  const topic = topics.find((t) => path.includes(t.key))?.value ?? "Unknown";
+
+  starlightRoute.head.push({
+    tag: "meta",
+    attrs: { "data-pagefind-meta": `Topic: ${topic}` },
+  });
+});