From 2c93542e5c3f30c9fd902b7e4978bdd12f168b78 Mon Sep 17 00:00:00 2001
From: Abhi <43648792+abhipatel12@users.noreply.github.com>
Date: Tue, 21 Oct 2025 14:36:02 -0400
Subject: [PATCH] Revert "Per-Auth Method Feature Flag for Model Routing
 (#11333)" (#11597)

---
 packages/cli/src/config/config.test.ts  |  1 -
 packages/core/src/config/config.test.ts | 47 ++++++-------------------
 packages/core/src/config/config.ts      | 22 ++----------
 3 files changed, 13 insertions(+), 57 deletions(-)

diff --git a/packages/cli/src/config/config.test.ts b/packages/cli/src/config/config.test.ts
index 1a8dab99e9..6bc23ad7d6 100644
--- a/packages/cli/src/config/config.test.ts
+++ b/packages/cli/src/config/config.test.ts
@@ -85,7 +85,6 @@ vi.mock('@google/gemini-cli-core', async () => {
   const actualServer = await vi.importActual<typeof ServerConfig>(
     '@google/gemini-cli-core',
   );
-
   return {
     ...actualServer,
     IdeClient: {
diff --git a/packages/core/src/config/config.test.ts b/packages/core/src/config/config.test.ts
index b5e99a5e37..0546f7cba6 100644
--- a/packages/core/src/config/config.test.ts
+++ b/packages/core/src/config/config.test.ts
@@ -574,52 +574,27 @@ describe('Server Config (config.ts)', () => {
     });
   });
 
-  describe('Model Router with Auth', () => {
-    it('should disable model router by default for oauth-personal', async () => {
-      const config = new Config({
-        ...baseParams,
-        useModelRouter: true,
-      });
-      await config.refreshAuth(AuthType.LOGIN_WITH_GOOGLE);
+  describe('UseModelRouter Configuration', () => {
+    it('should default useModelRouter to false when not provided', () => {
+      const config = new Config(baseParams);
       expect(config.getUseModelRouter()).toBe(false);
     });
 
-    it('should enable model router by default for other auth types', async () => {
-      const config = new Config({
+    it('should set useModelRouter to true when provided as true', () => {
+      const paramsWithModelRouter: ConfigParameters = {
         ...baseParams,
         useModelRouter: true,
-      });
-      await config.refreshAuth(AuthType.USE_GEMINI);
+      };
+      const config = new Config(paramsWithModelRouter);
       expect(config.getUseModelRouter()).toBe(true);
     });
 
-    it('should disable model router for specified auth type', async () => {
-      const config = new Config({
-        ...baseParams,
-        useModelRouter: true,
-        disableModelRouterForAuth: [AuthType.USE_GEMINI],
-      });
-      await config.refreshAuth(AuthType.USE_GEMINI);
-      expect(config.getUseModelRouter()).toBe(false);
-    });
-
-    it('should enable model router for other auth type', async () => {
-      const config = new Config({
-        ...baseParams,
-        useModelRouter: true,
-        disableModelRouterForAuth: [],
-      });
-      await config.refreshAuth(AuthType.LOGIN_WITH_GOOGLE);
-      expect(config.getUseModelRouter()).toBe(true);
-    });
-
-    it('should keep model router disabled when useModelRouter is false', async () => {
-      const config = new Config({
+    it('should set useModelRouter to false when explicitly provided as false', () => {
+      const paramsWithModelRouter: ConfigParameters = {
         ...baseParams,
         useModelRouter: false,
-        disableModelRouterForAuth: [AuthType.USE_GEMINI],
-      });
-      await config.refreshAuth(AuthType.LOGIN_WITH_GOOGLE);
+      };
+      const config = new Config(paramsWithModelRouter);
       expect(config.getUseModelRouter()).toBe(false);
     });
   });
diff --git a/packages/core/src/config/config.ts b/packages/core/src/config/config.ts
index 4955a0f95e..584e928cb0 100644
--- a/packages/core/src/config/config.ts
+++ b/packages/core/src/config/config.ts
@@ -47,7 +47,6 @@ import {
   DEFAULT_GEMINI_EMBEDDING_MODEL,
   DEFAULT_GEMINI_FLASH_MODEL,
   DEFAULT_GEMINI_MODEL,
-  DEFAULT_GEMINI_MODEL_AUTO,
   DEFAULT_THINKING_MODE,
 } from './models.js';
 import { shouldAttemptBrowserLaunch } from '../utils/browser.js';
@@ -279,7 +278,6 @@ export interface ConfigParameters {
   policyEngineConfig?: PolicyEngineConfig;
   output?: OutputSettings;
   useModelRouter?: boolean;
-  disableModelRouterForAuth?: AuthType[];
   enableMessageBusIntegration?: boolean;
   codebaseInvestigatorSettings?: CodebaseInvestigatorSettings;
   continueOnFailedApiCall?: boolean;
@@ -376,9 +374,7 @@ export class Config {
   private readonly messageBus: MessageBus;
   private readonly policyEngine: PolicyEngine;
   private readonly outputSettings: OutputSettings;
-  private useModelRouter: boolean;
-  private readonly initialUseModelRouter: boolean;
-  private readonly disableModelRouterForAuth?: AuthType[];
+  private readonly useModelRouter: boolean;
   private readonly enableMessageBusIntegration: boolean;
   private readonly codebaseInvestigatorSettings: CodebaseInvestigatorSettings;
   private readonly continueOnFailedApiCall: boolean;
@@ -474,11 +470,7 @@ export class Config {
     this.enableToolOutputTruncation = params.enableToolOutputTruncation ?? true;
     this.useSmartEdit = params.useSmartEdit ?? true;
     this.useWriteTodos = params.useWriteTodos ?? false;
-    this.initialUseModelRouter = params.useModelRouter ?? false;
-    this.useModelRouter = this.initialUseModelRouter;
-    this.disableModelRouterForAuth = params.disableModelRouterForAuth ?? [
-      AuthType.LOGIN_WITH_GOOGLE,
-    ];
+    this.useModelRouter = params.useModelRouter ?? false;
     this.enableMessageBusIntegration =
       params.enableMessageBusIntegration ?? false;
     this.codebaseInvestigatorSettings = {
@@ -549,16 +541,6 @@ export class Config {
   }
 
   async refreshAuth(authMethod: AuthType) {
-    this.useModelRouter = this.initialUseModelRouter;
-    if (this.disableModelRouterForAuth?.includes(authMethod)) {
-      this.useModelRouter = false;
-      if (this.model === DEFAULT_GEMINI_MODEL_AUTO) {
-        this.model = DEFAULT_GEMINI_MODEL;
-      }
-    } else {
-      this.model = DEFAULT_GEMINI_MODEL_AUTO;
-    }
-
     // Vertex and Genai have incompatible encryption and sending history with
     // thoughtSignature from Genai to Vertex will fail, we need to strip them
     if (