feat(simulator): use gemini-3-flash-preview with thinking for simulation

packages/cli/src/services/UserSimulator.ts

@@ -4,7 +4,12 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 import type { Config } from '@google/gemini-cli-core';
-import { debugLogger, LlmRole, resolveModel } from '@google/gemini-cli-core';
+import {
+  debugLogger,
+  LlmRole,
+  PREVIEW_GEMINI_FLASH_MODEL,
+  resolveModel,
+} from '@google/gemini-cli-core';
 import type { Writable } from 'node:stream';
 
 export class UserSimulator {
@@ -84,7 +89,7 @@ For example:
 Do NOT output markdown, explanations of your thought process, or quotes. Output ONLY the raw characters to send, <WAIT>, or <DONE>.`;
 
       const model = resolveModel(
-        this.config.getModel(),
+        PREVIEW_GEMINI_FLASH_MODEL,
         false, // useGemini3_1
         false, // useCustomToolModel
         this.config.getHasAccessToPreviewModel?.() ?? true,

packages/core/src/config/defaultModelConfigs.ts

@@ -277,7 +277,7 @@ export const DEFAULT_MODEL_CONFIGS: ModelConfigServiceConfig = {
       family: 'gemini-3',
       isPreview: true,
       isVisible: true,
-      features: { thinking: false, multimodalToolUse: true },
+      features: { thinking: true, multimodalToolUse: true },
     },
     'gemini-2.5-pro': {
       tier: 'pro',