fix(googlechat): normalize auth response headers

CHANGELOG.md

@@ -205,6 +205,7 @@ Docs: https://docs.openclaw.ai
 - Feishu: accept and honor `channels.feishu.blockStreaming` at the top level and per account, while keeping the legacy default off so Feishu cards no longer reject documented config or silently drop block replies. Fixes #75555. Thanks @vincentkoc.
 - Gateway/update: avoid `launchctl kickstart -k` immediately after fresh macOS update bootstraps, and unlink dangling global plugin-runtime symlinks during packaged postinstall and `doctor --fix` so upgrades no longer SIGTERM the newly booted Gateway or leave bundled plugin imports pointed at pruned `plugin-runtime-deps` trees. Completes #76261 and fixes #76466. (#76929)
 - Google Chat: normalize custom Google auth transport headers before google-auth/gaxios interceptors run, restoring webhook token verification when certificate retrieval expects Fetch `Headers`. Fixes #76742. Thanks @donbowman.
+- Google Chat: normalize Google auth certificate response headers before google-auth-library reads cache-control, so inbound webhook auth no longer rejects with `res?.headers.get is not a function`. Fixes #76880. Thanks @donbowman.
 - Doctor/plugins: reset stale `plugins.slots.memory` and `plugins.slots.contextEngine` references during `doctor --fix`, so cleanup of missing plugin config does not leave unrecoverable slot owners behind. Fixes #76550 and #76551. Thanks @vincentkoc.
 - Docs/WhatsApp: merge the duplicate top-level `web` objects in the gateway channel config example so copy-pasted WhatsApp config keeps both `web.whatsapp` and reconnect settings. Fixes #76619. Thanks @WadydX.
 - Plugins/Anthropic: expose Claude thinking profiles from the bundled provider-policy artifact so non-runtime callers keep Opus 4.7 `adaptive`, `xhigh`, and `max` instead of downgrading to `high`. Fixes #76779. Thanks @tomascupr and @iAbhi001.

extensions/googlechat/src/google-auth.runtime.test.ts

@@ -348,6 +348,9 @@ describe("googlechat google auth runtime", () => {
       expect(transport.interceptors.request.add).toHaveBeenCalledWith({
         resolved: expect.any(Function),
       });
+      expect(transport.interceptors.response.add).toHaveBeenCalledWith({
+        resolved: expect.any(Function),
+      });
       expect("window" in globalThis).toBe(false);
     } finally {
       if (originalWindowDescriptor) {
@@ -369,6 +372,20 @@ describe("googlechat google auth runtime", () => {
     expect(normalized.headers.get("x-test")).toBe("1");
   });
 
+  it("normalizes Google auth response headers before upstream cache-control reads", () => {
+    const response = {
+      data: {},
+      headers: {
+        "cache-control": "public, max-age=3600",
+      },
+    };
+
+    const normalized = __testing.normalizeGoogleAuthResponseHeaders(response);
+
+    expect(normalized.headers).toBeInstanceOf(Headers);
+    expect(normalized.headers.get("cache-control")).toBe("public, max-age=3600");
+  });
+
   it("rejects service-account credentials that override Google auth endpoints", async () => {
     await expect(
       resolveValidatedGoogleChatCredentials({

extensions/googlechat/src/google-auth.runtime.ts

@@ -23,6 +23,9 @@ type GoogleAuthTransport = InstanceType<GaxiosModule["Gaxios"]>;
 type GoogleAuthRequestWithUnknownHeaders = RequestInit & {
   headers?: unknown;
 };
+type GoogleAuthResponseWithUnknownHeaders = {
+  headers?: unknown;
+};
 type GuardedGoogleAuthRequestInit = RequestInit & {
   agent?: unknown;
   cert?: unknown;
@@ -79,12 +82,24 @@ function normalizeGoogleAuthPreparedRequestHeaders<T extends GoogleAuthRequestWi
   return config as T & { headers: Headers };
 }
 
+function normalizeGoogleAuthResponseHeaders<T extends GoogleAuthResponseWithUnknownHeaders>(
+  response: T,
+): T & { headers: Headers } {
+  if (!(response.headers instanceof Headers)) {
+    response.headers = new Headers(response.headers as HeadersInit | undefined);
+  }
+  return response as T & { headers: Headers };
+}
+
 function installGoogleAuthHeaderCompatibilityInterceptor(
   transport: GoogleAuthTransport,
 ): GoogleAuthTransport {
   transport.interceptors.request.add({
     resolved: async (config) => normalizeGoogleAuthPreparedRequestHeaders(config),
   });
+  transport.interceptors.response.add({
+    resolved: async (response) => normalizeGoogleAuthResponseHeaders(response),
+  });
   return transport;
 }
 
@@ -558,6 +573,7 @@ export const __testing = {
     googleAuthTransportPromise = null;
   },
   normalizeGoogleAuthPreparedRequestHeaders,
+  normalizeGoogleAuthResponseHeaders,
   resolveGoogleAuthEnvProxyUrl,
   validateGoogleChatServiceAccountCredentials,
 };