Remove useModelRouter experimental flag (#13593)

Author: Adib234

docs/cli/model-routing.md

@@ -25,18 +25,6 @@ Here's how it works:
     `packages/cli/src/zed-integration/zedIntegration.ts` which checks if
     `isInFallbackMode()` is true.
 
-## Configuration
-
-Model routing is controlled by the `useModelRouter` setting in your
-`settings.json` file.
-
-- **`"experimental.useModelRouter": true` (Default):** Enables the model
-  routing/fallback feature.
-
-- **`"experimental.useModelRouter": false`:** Disables the model
-  routing/fallback feature. If a model fails, the CLI will not attempt to switch
-  to a fallback model.
-
 ### Model Selection Precedence
 
 The model used by Gemini CLI is determined by the following order of precedence:
@@ -50,7 +38,4 @@ The model used by Gemini CLI is determined by the following order of precedence:
     model specified in the `model.name` property of your `settings.json` file
     will be used.
 4.  **Default Model:** If none of the above are set, the default model will be
-    used. The default model is determined by the `useModelRouter` setting:
-    - If `useModelRouter` is `true`, the default model is `"auto"`.
-    - If `useModelRouter` is `false`, the default model is the standard Gemini
-      model.
+    used. The default model is `auto`

docs/cli/settings.md

@@ -106,8 +106,7 @@ they appear in the UI.
 
 ### Experimental
 
-| UI Label                            | Setting                                                 | Description                                                                   | Default |
-| ----------------------------------- | ------------------------------------------------------- | ----------------------------------------------------------------------------- | ------- |
-| Use Model Router                    | `experimental.useModelRouter`                           | Enable model routing to route requests to the best model based on complexity. | `true`  |
-| Enable Codebase Investigator        | `experimental.codebaseInvestigatorSettings.enabled`     | Enable the Codebase Investigator agent.                                       | `true`  |
-| Codebase Investigator Max Num Turns | `experimental.codebaseInvestigatorSettings.maxNumTurns` | Maximum number of turns for the Codebase Investigator agent.                  | `10`    |
+| UI Label                            | Setting                                                 | Description                                                  | Default |
+| ----------------------------------- | ------------------------------------------------------- | ------------------------------------------------------------ | ------- |
+| Enable Codebase Investigator        | `experimental.codebaseInvestigatorSettings.enabled`     | Enable the Codebase Investigator agent.                      | `true`  |
+| Codebase Investigator Max Num Turns | `experimental.codebaseInvestigatorSettings.maxNumTurns` | Maximum number of turns for the Codebase Investigator agent. | `10`    |

docs/get-started/configuration.md

@@ -563,12 +563,6 @@ their corresponding top-level category object in your `settings.json` file.
   - **Default:** `false`
   - **Requires restart:** Yes
 
-- **`experimental.useModelRouter`** (boolean):
-  - **Description:** Enable model routing to route requests to the best model
-    based on complexity.
-  - **Default:** `true`
-  - **Requires restart:** Yes
-
 - **`experimental.codebaseInvestigatorSettings.enabled`** (boolean):
   - **Description:** Enable the Codebase Investigator agent.
   - **Default:** `true`

packages/cli/src/config/config.test.ts

@@ -9,8 +9,6 @@ import * as os from 'node:os';
 import * as path from 'node:path';
 import {
   DEFAULT_FILE_FILTERING_OPTIONS,
-  DEFAULT_GEMINI_MODEL,
-  DEFAULT_GEMINI_MODEL_AUTO,
   OutputFormat,
   SHELL_TOOL_NAME,
   WRITE_FILE_TOOL_NAME,
@@ -1364,100 +1362,6 @@ describe('loadCliConfig model selection', () => {
   });
 });
 
-describe('loadCliConfig model selection with model router', () => {
-  beforeEach(() => {
-    vi.spyOn(ExtensionManager.prototype, 'getExtensions').mockReturnValue([]);
-  });
-
-  afterEach(() => {
-    vi.resetAllMocks();
-  });
-
-  it('should use auto model when useModelRouter is true and no model is provided', async () => {
-    process.argv = ['node', 'script.js'];
-    const argv = await parseArguments({} as Settings);
-    const config = await loadCliConfig(
-      {
-        experimental: {
-          useModelRouter: true,
-        },
-      },
-      'test-session',
-      argv,
-    );
-
-    expect(config.getModel()).toBe(DEFAULT_GEMINI_MODEL_AUTO);
-  });
-
-  it('should use default model when useModelRouter is false and no model is provided', async () => {
-    process.argv = ['node', 'script.js'];
-    const argv = await parseArguments({} as Settings);
-    const config = await loadCliConfig(
-      {
-        experimental: {
-          useModelRouter: false,
-        },
-      },
-      'test-session',
-      argv,
-    );
-
-    expect(config.getModel()).toBe(DEFAULT_GEMINI_MODEL);
-  });
-
-  it('should prioritize argv over useModelRouter', async () => {
-    process.argv = ['node', 'script.js', '--model', 'gemini-from-argv'];
-    const argv = await parseArguments({} as Settings);
-    const config = await loadCliConfig(
-      {
-        experimental: {
-          useModelRouter: true,
-        },
-      },
-      'test-session',
-      argv,
-    );
-
-    expect(config.getModel()).toBe('gemini-from-argv');
-  });
-
-  it('should prioritize settings over useModelRouter', async () => {
-    process.argv = ['node', 'script.js'];
-    const argv = await parseArguments({} as Settings);
-    const config = await loadCliConfig(
-      {
-        experimental: {
-          useModelRouter: true,
-        },
-        model: {
-          name: 'gemini-from-settings',
-        },
-      },
-      'test-session',
-      argv,
-    );
-
-    expect(config.getModel()).toBe('gemini-from-settings');
-  });
-
-  it('should prioritize environment variable over useModelRouter', async () => {
-    process.argv = ['node', 'script.js'];
-    vi.stubEnv('GEMINI_MODEL', 'gemini-from-env');
-    const argv = await parseArguments({} as Settings);
-    const config = await loadCliConfig(
-      {
-        experimental: {
-          useModelRouter: true,
-        },
-      },
-      'test-session',
-      argv,
-    );
-
-    expect(config.getModel()).toBe('gemini-from-env');
-  });
-});
-
 describe('loadCliConfig folderTrust', () => {
   beforeEach(() => {
     vi.resetAllMocks();
@@ -1633,32 +1537,6 @@ describe('loadCliConfig useRipgrep', () => {
     const config = await loadCliConfig(settings, 'test-session', argv);
     expect(config.getUseRipgrep()).toBe(true);
   });
-
-  describe('loadCliConfig useModelRouter', () => {
-    it('should be true by default when useModelRouter is not set in settings', async () => {
-      process.argv = ['node', 'script.js'];
-      const argv = await parseArguments({} as Settings);
-      const settings: Settings = {};
-      const config = await loadCliConfig(settings, 'test-session', argv);
-      expect(config.getUseModelRouter()).toBe(true);
-    });
-
-    it('should be true when useModelRouter is set to true in settings', async () => {
-      process.argv = ['node', 'script.js'];
-      const argv = await parseArguments({} as Settings);
-      const settings: Settings = { experimental: { useModelRouter: true } };
-      const config = await loadCliConfig(settings, 'test-session', argv);
-      expect(config.getUseModelRouter()).toBe(true);
-    });
-
-    it('should be false when useModelRouter is explicitly set to false in settings', async () => {
-      process.argv = ['node', 'script.js'];
-      const argv = await parseArguments({} as Settings);
-      const settings: Settings = { experimental: { useModelRouter: false } };
-      const config = await loadCliConfig(settings, 'test-session', argv);
-      expect(config.getUseModelRouter()).toBe(false);
-    });
-  });
 });
 
 describe('screenReader configuration', () => {

packages/cli/src/config/config.ts

@@ -15,7 +15,6 @@ import {
   setGeminiMdFilename as setServerGeminiMdFilename,
   getCurrentGeminiMdFilename,
   ApprovalMode,
-  DEFAULT_GEMINI_MODEL,
   DEFAULT_GEMINI_MODEL_AUTO,
   DEFAULT_GEMINI_EMBEDDING_MODEL,
   DEFAULT_FILE_FILTERING_OPTIONS,
@@ -580,10 +579,7 @@ export async function loadCliConfig(
     extraExcludes.length > 0 ? extraExcludes : undefined,
   );
 
-  const useModelRouter = settings.experimental?.useModelRouter ?? true;
-  const defaultModel = useModelRouter
-    ? DEFAULT_GEMINI_MODEL_AUTO
-    : DEFAULT_GEMINI_MODEL;
+  const defaultModel = DEFAULT_GEMINI_MODEL_AUTO;
   const resolvedModel: string =
     argv.model ||
     process.env['GEMINI_MODEL'] ||
@@ -674,7 +670,6 @@ export async function loadCliConfig(
     output: {
       format: (argv.outputFormat ?? settings.output?.format) as OutputFormat,
     },
-    useModelRouter,
     enableMessageBusIntegration,
     codebaseInvestigatorSettings:
       settings.experimental?.codebaseInvestigatorSettings,

packages/cli/src/config/settingsSchema.test.ts

@@ -345,21 +345,6 @@ describe('SettingsSchema', () => {
         getSettingsSchema().general.properties.previewFeatures.description,
       ).toBe('Enable preview features (e.g., preview models).');
     });
-
-    it('should have useModelRouter setting in schema', () => {
-      expect(
-        getSettingsSchema().experimental.properties.useModelRouter,
-      ).toBeDefined();
-      expect(
-        getSettingsSchema().experimental.properties.useModelRouter.type,
-      ).toBe('boolean');
-      expect(
-        getSettingsSchema().experimental.properties.useModelRouter.category,
-      ).toBe('Experimental');
-      expect(
-        getSettingsSchema().experimental.properties.useModelRouter.default,
-      ).toBe(true);
-    });
   });
 
   it('has JSON schema definitions for every referenced ref', () => {

packages/cli/src/config/settingsSchema.ts

@@ -1281,16 +1281,6 @@ const SETTINGS_SCHEMA = {
           'Enables extension loading/unloading within the CLI session.',
         showInDialog: false,
       },
-      useModelRouter: {
-        type: 'boolean',
-        label: 'Use Model Router',
-        category: 'Experimental',
-        requiresRestart: true,
-        default: true,
-        description:
-          'Enable model routing to route requests to the best model based on complexity.',
-        showInDialog: true,
-      },
       codebaseInvestigatorSettings: {
         type: 'object',
         label: 'Codebase Investigator Settings',

packages/cli/src/services/BuiltinCommandLoader.test.ts

@@ -95,7 +95,6 @@ describe('BuiltinCommandLoader', () => {
     vi.clearAllMocks();
     mockConfig = {
       getFolderTrust: vi.fn().mockReturnValue(true),
-      getUseModelRouter: () => false,
       getEnableMessageBusIntegration: () => false,
       getEnableExtensionReloading: () => false,
     } as unknown as Config;
@@ -168,28 +167,6 @@ describe('BuiltinCommandLoader', () => {
     expect(permissionsCmd).toBeUndefined();
   });
 
-  it('should include modelCommand when getUseModelRouter is true', async () => {
-    const mockConfigWithModelRouter = {
-      ...mockConfig,
-      getUseModelRouter: () => true,
-    } as unknown as Config;
-    const loader = new BuiltinCommandLoader(mockConfigWithModelRouter);
-    const commands = await loader.loadCommands(new AbortController().signal);
-    const modelCmd = commands.find((c) => c.name === 'model');
-    expect(modelCmd).toBeDefined();
-  });
-
-  it('should not include modelCommand when getUseModelRouter is false', async () => {
-    const mockConfigWithoutModelRouter = {
-      ...mockConfig,
-      getUseModelRouter: () => false,
-    } as unknown as Config;
-    const loader = new BuiltinCommandLoader(mockConfigWithoutModelRouter);
-    const commands = await loader.loadCommands(new AbortController().signal);
-    const modelCmd = commands.find((c) => c.name === 'model');
-    expect(modelCmd).toBeUndefined();
-  });
-
   it('should include policies command when message bus integration is enabled', async () => {
     const mockConfigWithMessageBus = {
       ...mockConfig,
@@ -220,7 +197,6 @@ describe('BuiltinCommandLoader profile', () => {
     vi.resetModules();
     mockConfig = {
       getFolderTrust: vi.fn().mockReturnValue(false),
-      getUseModelRouter: () => false,
       getCheckpointingEnabled: () => false,
       getEnableMessageBusIntegration: () => false,
       getEnableExtensionReloading: () => false,

packages/cli/src/services/BuiltinCommandLoader.ts

@@ -73,7 +73,7 @@ export class BuiltinCommandLoader implements ICommandLoader {
       initCommand,
       mcpCommand,
       memoryCommand,
-      ...(this.config?.getUseModelRouter() ? [modelCommand] : []),
+      modelCommand,
       ...(this.config?.getFolderTrust() ? [permissionsCommand] : []),
       privacyCommand,
       ...(this.config?.getEnableMessageBusIntegration()

packages/cli/src/ui/components/ModelDialog.test.tsx

@@ -51,7 +51,6 @@ const renderComponent = (
         getDebugMode: vi.fn(() => false),
         getContentGeneratorConfig: vi.fn(() => ({ authType: 'mock' })),
         getUseSmartEdit: vi.fn(() => false),
-        getUseModelRouter: vi.fn(() => false),
         getProxy: vi.fn(() => undefined),
         isInteractive: vi.fn(() => false),