Improve quota- and resource-related 429 error handling, also taking Code Assist customer tiers into consideration (#3609)

packages/core/src/utils/quotaErrorDetection.ts

@@ -0,0 +1,82 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+export interface ApiError {
+  error: {
+    code: number;
+    message: string;
+    status: string;
+    details: unknown[];
+  };
+}
+
+interface StructuredError {
+  message: string;
+  status?: number;
+}
+
+export function isApiError(error: unknown): error is ApiError {
+  return (
+    typeof error === 'object' &&
+    error !== null &&
+    'error' in error &&
+    typeof (error as ApiError).error === 'object' &&
+    'message' in (error as ApiError).error
+  );
+}
+
+export function isStructuredError(error: unknown): error is StructuredError {
+  return (
+    typeof error === 'object' &&
+    error !== null &&
+    'message' in error &&
+    typeof (error as StructuredError).message === 'string'
+  );
+}
+
+export function isProQuotaExceededError(error: unknown): boolean {
+  // Check for Pro quota exceeded errors by looking for the specific pattern
+  // This will match patterns like:
+  // - "Quota exceeded for quota metric 'Gemini 2.5 Pro Requests'"
+  // - "Quota exceeded for quota metric 'Gemini 1.5-preview Pro Requests'"
+  // - "Quota exceeded for quota metric 'Gemini beta-3.0 Pro Requests'"
+  // - "Quota exceeded for quota metric 'Gemini experimental-v2 Pro Requests'"
+  // We use string methods instead of regex to avoid ReDoS vulnerabilities
+
+  const checkMessage = (message: string): boolean =>
+    message.includes("Quota exceeded for quota metric 'Gemini") &&
+    message.includes("Pro Requests'");
+
+  if (typeof error === 'string') {
+    return checkMessage(error);
+  }
+
+  if (isStructuredError(error)) {
+    return checkMessage(error.message);
+  }
+
+  if (isApiError(error)) {
+    return checkMessage(error.error.message);
+  }
+
+  return false;
+}
+
+export function isGenericQuotaExceededError(error: unknown): boolean {
+  if (typeof error === 'string') {
+    return error.includes('Quota exceeded for quota metric');
+  }
+
+  if (isStructuredError(error)) {
+    return error.message.includes('Quota exceeded for quota metric');
+  }
+
+  if (isApiError(error)) {
+    return error.error.message.includes('Quota exceeded for quota metric');
+  }
+
+  return false;
+}