fix proxy normalization

packages/core/src/utils/proxyUtils.ts

@@ -0,0 +1,37 @@
+/**
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * Normalizes a proxy URL to ensure it has a valid protocol prefix.
+ *
+ * Many proxy tools and environment variables provide proxy addresses without
+ * a protocol prefix (e.g., "127.0.0.1:7860" instead of "http://127.0.0.1:7860").
+ * This function adds the "http://" prefix if missing, since HTTP proxies are
+ * the most common default.
+ *
+ * @param proxyUrl - The proxy URL to normalize
+ * @returns The normalized proxy URL with protocol prefix, or undefined if input is undefined/empty
+ */
+export function normalizeProxyUrl(
+  proxyUrl: string | undefined,
+): string | undefined {
+  if (!proxyUrl) {
+    return undefined;
+  }
+
+  const trimmed = proxyUrl.trim();
+  if (!trimmed) {
+    return undefined;
+  }
+
+  // Check if the URL already has a protocol prefix
+  if (/^https?:\/\//i.test(trimmed)) {
+    return trimmed;
+  }
+
+  // Add http:// prefix for proxy URLs without protocol
+  // HTTP is the default for most proxy configurations
+  return `http://${trimmed}`;
+}