chore: import upstream snapshot with attribution

open-sse/services/proxyAutoSelector.ts

@@ -0,0 +1,58 @@
+/**
+ * proxyAutoSelector.ts — Validation-layer proxy auto-selection service
+ *
+ * Wraps the low-level proxy fallback engine for use in the provider validation
+ * pipeline. When a direct validation request fails with a connectivity error,
+ * this service finds a working proxy and lets the caller retry with it.
+ *
+ * Proxies are discovered and returned for the current request only — they are
+ * NOT persisted to the proxy registry. Short-term caching (5-minute TTL) is
+ * handled by the in-memory cache in proxyFallback.ts.
+ */
+
+import {
+  findWorkingProxy,
+  clearProxyFallbackCache,
+} from "@omniroute/open-sse/utils/proxyFallback.ts";
+import { isFeatureFlagEnabled } from "@/shared/utils/featureFlags";
+
+// ---------------------------------------------------------------------------
+// Public API
+// ---------------------------------------------------------------------------
+
+/**
+ * Select a working proxy for the given target URL.
+ *
+ * Extracts the hostname, delegates to the underlying proxy fallback engine
+ * (candidate discovery + parallel testing + caching), and returns a working
+ * proxy URL or null if none can be found.
+ *
+ * The discovered proxy is NOT persisted to the registry — it is returned for
+ * the current request only. Short-term caching is handled in-memory within
+ * proxyFallback.ts (5-minute TTL).
+ *
+ * @param targetUrl The full URL to find a working proxy for.
+ * @returns A working proxy URL, or null if none was found.
+ */
+export async function selectProxyForValidation(targetUrl: string): Promise<string | null> {
+  if (!isFeatureFlagEnabled("PROXY_AUTO_SELECT_ENABLED")) return null;
+  if (!targetUrl) return null;
+
+  let hostname: string;
+  try {
+    hostname = new URL(targetUrl).hostname;
+    if (!hostname) return null;
+  } catch {
+    return null;
+  }
+
+  return findWorkingProxy(hostname, targetUrl);
+}
+
+/**
+ * Clear the in-memory proxy fallback cache.
+ * Useful after proxy config changes or in tests.
+ */
+export function clearProxySelectionCache(): void {
+  clearProxyFallbackCache();
+}