castle-search: resolve Google links lazily, in Chrome, not eagerly over plain HTTPHEADmaster

The Node-side resolver sent one curl-like request per result with no
cookies, JS or browser; Google answers that with its 'Verifying your
request' countdown after a handful, and the testing itself triggered it.
A click or direct navigation in Chrome redirects at once (measured).

Search now leaves Google links wrapped and prints the breadcrumb Google
shows for each. castle_cdp_resolve follows one wrapped link in a Chrome tab
when the agent picks it, accepts only google.com/goto?url=<token>, and
reports the verification page instead of waiting it out.

1 files changed, 19 insertions, 0 deletions

diff --git a/castle-search/src/errors.ts b/castle-search/src/errors.ts
index 2318b27..95fa7ef 100644
--- a/castle-search/src/errors.ts
+++ b/castle-search/src/errors.ts
@@ -81,3 +81,22 @@ export class SearchAbortedError extends Error {
 }
 
 export const messageOf = (e: unknown): string => (e instanceof Error ? e.message : String(e));
+
+/**
+ * Google answered a `/goto` link with its "Verifying your request" page instead
+ * of redirecting. It is a bot check with a countdown; it is reported, never
+ * waited out or clicked through.
+ */
+export class GoogleVerificationError extends Error {
+  override readonly name = "GoogleVerificationError";
+  readonly pageUrl: string;
+  constructor(pageUrl: string) {
+    super(
+      "Google showed its \"Verifying your request\" page instead of redirecting, so the real URL could not be " +
+        "read. This is a rate-based bot check: opening many links in a row triggers it, and it eases after a few " +
+        "minutes. Do not retry in a loop. Use the breadcrumb printed under the result to judge where it points, " +
+        "pick fewer links, or search again with another engine (duckduckgo, brave, bing), which return real URLs.",
+    );
+    this.pageUrl = pageUrl;
+  }
+}