fix(agents): classify Google invalid API keys as auth (#114825)

src/agents/embedded-agent-helpers/failover-matches.test.ts

@@ -106,6 +106,28 @@ describe("Z.ai vendor error codes (#48988)", () => {
   });
 });
 
+describe("Google invalid API key errors (#114784)", () => {
+  it("classifies the Google Generative AI invalid-key response as auth", () => {
+    const raw =
+      "Google Generative AI API error (400): API key not valid. Please pass a valid API key. [code=INVALID_ARGUMENT]";
+
+    expect(isAuthErrorMessage(raw)).toBe(true);
+    expect(classifyFailoverReason(raw)).toBe("auth");
+  });
+
+  it("classifies the structured API_KEY_INVALID variant as auth", () => {
+    expect(isAuthErrorMessage('{"code":"API_KEY_INVALID"}')).toBe(true);
+  });
+
+  it("does not treat unrelated Google invalid arguments as auth", () => {
+    const raw =
+      "Google Generative AI API error (400): Request contains an invalid argument. [code=INVALID_ARGUMENT]";
+
+    expect(isAuthErrorMessage(raw)).toBe(false);
+    expect(classifyFailoverReason(raw)).toBeNull();
+  });
+});
+
 describe("Chinese provider overload messages", () => {
   const ZHIPU_OVERLOAD = "[1305][该模型当前访问量过大，请您稍后再试]";
 

src/agents/embedded-agent-helpers/failover-matches.ts

@@ -19,6 +19,8 @@ const HIGH_CONFIDENCE_AUTH_PERMANENT_PATTERNS = [
 
 const AMBIGUOUS_AUTH_ERROR_PATTERNS = [
   /invalid[_ ]?api[_ ]?key/,
+  // Google returns HTTP 400 with these variants for an invalid Generative AI key (#114784).
+  /api[_ ]?key(?:[_ ]?(?:is )?(?:invalid|not valid))\b/i,
   /could not (?:authenticate|validate).*(?:api[_ ]?key|credentials)/i,
   "permission_error",
 ] as const satisfies readonly ErrorPattern[];

src/agents/model-fallback.test.ts

@@ -1914,6 +1914,42 @@ describe("runWithModelFallback", () => {
     expect(result.provider).toBe("anthropic");
   });
 
+  it("continues to the next model after a Google invalid-key response (#114784)", async () => {
+    const cfg = makeCfg({
+      agents: {
+        defaults: {
+          model: {
+            primary: "google/gemini-3.1-pro-preview",
+            fallbacks: ["anthropic/claude-sonnet-4-6"],
+          },
+        },
+      },
+    });
+    const googleInvalidKey = new Error(
+      "Google Generative AI API error (400): API key not valid. Please pass a valid API key. [code=INVALID_ARGUMENT]",
+    );
+    const run = vi
+      .fn()
+      .mockRejectedValueOnce(googleInvalidKey)
+      .mockResolvedValueOnce("fallback ok");
+
+    const result = await runWithModelFallback({
+      cfg,
+      provider: "google",
+      model: "gemini-3.1-pro-preview",
+      run,
+    });
+
+    expect(result.result).toBe("fallback ok");
+    expect(result.provider).toBe("anthropic");
+    expect(result.attempts[0]).toMatchObject({
+      provider: "google",
+      model: "gemini-3.1-pro-preview",
+      reason: "auth",
+    });
+    expect(run).toHaveBeenCalledTimes(2);
+  });
+
   it("keeps provider failover metadata authoritative over nested session locks", async () => {
     const cfg = makeCfg({
       agents: {