well-known: add /.well-known/ai-catalog.json (Agentic Resource Discovery)

dist/well-known.js

@@ -276,6 +276,55 @@ return Promise.all([
       return data;
     });
   }),
+  // Agentic Resource Discovery (ARD) - checked by Lighthouse's agentic-browsing category.
+  // Resolution follows Lighthouse's ARD gatherer (core/gather/gatherers/agentic/ard.js):
+  // <link rel="ai-catalog"> in the document wins, otherwise /.well-known/ai-catalog.json.
+  // Keyed by the well-known path either way; `catalog_url` is added only when the
+  // link points somewhere other than the default location.
+  (() => {
+    const wellKnownUrl = '/.well-known/ai-catalog.json';
+    let catalogUrl = null;
+    try {
+      const link = document.querySelector('link[rel~="ai-catalog" i]');
+      if (link && link.href) {
+        const target = new URL(link.href, location.href);
+        if (target.origin !== location.origin || target.pathname !== wellKnownUrl) {
+          catalogUrl = target.href;
+        }
+      }
+    } catch (e) {
+      // No usable link, fall back to the well-known path.
+    }
+    return parseResponse(catalogUrl || wellKnownUrl, r => {
+      return r.text().then(text => {
+        let result = {
+          spec_version: null,
+          has_host: false,
+          entries_count: 0,
+          entry_types: []
+        };
+        try {
+          const data = JSON.parse(text);
+          result.spec_version = typeof data.specVersion === 'string' ? data.specVersion : null;
+          result.has_host = !!(data.host && typeof data.host === 'object');
+          if (Array.isArray(data.entries)) {
+            result.entries_count = data.entries.length;
+            result.entry_types = [...new Set(data.entries
+              .map(e => e && typeof e.type === 'string' ? e.type : null)
+              .filter(Boolean))].slice(0, 20);
+          }
+        } catch (e) {
+          // Failed to parse JSON, result will contain default values.
+        }
+        return result;
+      });
+    }).then(([, resultObj]) => {
+      if (catalogUrl) {
+        resultObj.catalog_url = catalogUrl;
+      }
+      return [wellKnownUrl, resultObj];
+    });
+  })(),
   parseResponseWithRedirects('/.well-known/security.txt', r => {
     let data = {
       status: r.status,