Add experiment logging and add caching experiment (#12862)

packages/core/src/code_assist/experiments/flagNames.ts

@@ -0,0 +1,14 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+export const ExperimentFlags = {
+  CONTEXT_COMPRESSION_THRESHOLD:
+    'GeminiCLIContextCompression__threshold_fraction',
+  USER_CACHING: 'GcliUserCaching__user_caching',
+} as const;
+
+export type ExperimentFlagName =
+  (typeof ExperimentFlags)[keyof typeof ExperimentFlags];