fix: Show experiment values in settings UI for compressionThreshold (#16267)

Co-authored-by: Vedant Mahajan <vedant.04.mahajan@gmail.com>

packages/cli/src/utils/settingsUtils.ts

@@ -16,6 +16,8 @@ import type {
   SettingsValue,
 } from '../config/settingsSchema.js';
 import { getSettingsSchema } from '../config/settingsSchema.js';
+import type { Config } from '@google/gemini-cli-core';
+import { ExperimentFlags } from '@google/gemini-cli-core';
 
 // The schema is now nested, but many parts of the UI and logic work better
 // with a flattened structure and dot-notation keys. This section flattens the
@@ -96,6 +98,28 @@ export function getDefaultValue(key: string): SettingsValue {
   return getFlattenedSchema()[key]?.default;
 }
 
+/**
+ * Get the effective default value for a setting, checking experiment values when available.
+ * For settings like compressionThreshold, this will return the experiment value if set,
+ * otherwise falls back to the schema default.
+ */
+export function getEffectiveDefaultValue(
+  key: string,
+  config?: Config,
+): SettingsValue {
+  if (key === 'model.compressionThreshold' && config) {
+    const experiments = config.getExperiments();
+    const experimentValue =
+      experiments?.flags[ExperimentFlags.CONTEXT_COMPRESSION_THRESHOLD]
+        ?.floatValue;
+    if (experimentValue !== undefined && experimentValue !== 0) {
+      return experimentValue;
+    }
+  }
+
+  return getDefaultValue(key);
+}
+
 /**
  * Get all setting keys that require restart
  */