feat: ensure codebase investigator uses preview model when main agent does (#14412)

packages/core/src/agents/codebase-investigator.ts

@@ -11,7 +11,7 @@ import {
   LS_TOOL_NAME,
   READ_FILE_TOOL_NAME,
 } from '../tools/tool-names.js';
-import { DEFAULT_GEMINI_MODEL } from '../config/models.js';
+import { GEMINI_MODEL_ALIAS_PRO } from '../config/models.js';
 import { z } from 'zod';
 
 // Define a type that matches the outputConfig schema for type safety.
@@ -69,7 +69,7 @@ export const CodebaseInvestigatorAgent: AgentDefinition<
   processOutput: (output) => JSON.stringify(output, null, 2),
 
   modelConfig: {
-    model: DEFAULT_GEMINI_MODEL,
+    model: GEMINI_MODEL_ALIAS_PRO,
     temp: 0.1,
     top_p: 0.95,
     thinkingBudget: -1,