Structured JSON Output (#8119)

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

@@ -1972,6 +1972,55 @@ describe('loadCliConfig fileFiltering', () => {
   );
 });
 
+describe('Output Format Configuration', () => {
+  const originalArgv = process.argv;
+
+  afterEach(() => {
+    process.argv = originalArgv;
+    vi.restoreAllMocks();
+  });
+
+  it('should default to text format when no setting or flag is provided', async () => {
+    process.argv = ['node', 'script.js'];
+    const argv = await parseArguments({} as Settings);
+    const config = await loadCliConfig(
+      {} as Settings,
+      [],
+      'test-session',
+      argv,
+    );
+    expect(config.getOutputFormat()).toBe(ServerConfig.OutputFormat.TEXT);
+  });
+
+  it('should use the format from settings when no flag is provided', async () => {
+    process.argv = ['node', 'script.js'];
+    const settings: Settings = { output: { format: 'json' } };
+    const argv = await parseArguments(settings);
+    const config = await loadCliConfig(settings, [], 'test-session', argv);
+    expect(config.getOutputFormat()).toBe(ServerConfig.OutputFormat.JSON);
+  });
+
+  it('should use the format from the flag when provided', async () => {
+    process.argv = ['node', 'script.js', '--output-format', 'json'];
+    const argv = await parseArguments({} as Settings);
+    const config = await loadCliConfig(
+      {} as Settings,
+      [],
+      'test-session',
+      argv,
+    );
+    expect(config.getOutputFormat()).toBe(ServerConfig.OutputFormat.JSON);
+  });
+
+  it('should prioritize the flag over the setting', async () => {
+    process.argv = ['node', 'script.js', '--output-format', 'text'];
+    const settings: Settings = { output: { format: 'json' } };
+    const argv = await parseArguments(settings);
+    const config = await loadCliConfig(settings, [], 'test-session', argv);
+    expect(config.getOutputFormat()).toBe(ServerConfig.OutputFormat.TEXT);
+  });
+});
+
 describe('parseArguments with positional prompt', () => {
   const originalArgv = process.argv;
 

packages/cli/src/config/config.ts

@@ -15,6 +15,7 @@ import type {
   TelemetryTarget,
   FileFilteringOptions,
   MCPServerConfig,
+  OutputFormat,
 } from '@google/gemini-cli-core';
 import { extensionsCommand } from '../commands/extensions.js';
 import {
@@ -81,6 +82,7 @@ export interface CliArgs {
   useSmartEdit: boolean | undefined;
   sessionSummary: string | undefined;
   promptWords: string[] | undefined;
+  outputFormat: string | undefined;
 }
 
 export async function parseArguments(settings: Settings): Promise<CliArgs> {
@@ -234,6 +236,11 @@ export async function parseArguments(settings: Settings): Promise<CliArgs> {
           type: 'string',
           description: 'File to write session summary to.',
         })
+        .option('output-format', {
+          type: 'string',
+          description: 'The format of the CLI output.',
+          choices: ['text', 'json'],
+        })
         .deprecateOption(
           'telemetry',
           'Use the "telemetry.enabled" setting in settings.json instead. This flag will be removed in a future version.',
@@ -627,6 +634,9 @@ export async function loadCliConfig(
     enableToolOutputTruncation: settings.tools?.enableToolOutputTruncation,
     eventEmitter: appEvents,
     useSmartEdit: argv.useSmartEdit ?? settings.useSmartEdit,
+    output: {
+      format: (argv.outputFormat ?? settings.output?.format) as OutputFormat,
+    },
   });
 }
 

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

@@ -1078,6 +1078,30 @@ describe('Settings Loading and Merging', () => {
       });
     });
 
+    it('should merge output format settings, with workspace taking precedence', () => {
+      (mockFsExistsSync as Mock).mockReturnValue(true);
+      const userSettingsContent = {
+        output: { format: 'text' },
+      };
+      const workspaceSettingsContent = {
+        output: { format: 'json' },
+      };
+
+      (fs.readFileSync as Mock).mockImplementation(
+        (p: fs.PathOrFileDescriptor) => {
+          if (p === USER_SETTINGS_PATH)
+            return JSON.stringify(userSettingsContent);
+          if (p === MOCK_WORKSPACE_SETTINGS_PATH)
+            return JSON.stringify(workspaceSettingsContent);
+          return '{}';
+        },
+      );
+
+      const settings = loadSettings(MOCK_WORKSPACE_DIR);
+
+      expect(settings.merged.output?.format).toBe('json');
+    });
+
     it('should handle chatCompression when only in user settings', () => {
       (mockFsExistsSync as Mock).mockImplementation(
         (p: fs.PathLike) => p === USER_SETTINGS_PATH,

packages/cli/src/config/settingsSchema.ts

@@ -187,6 +187,30 @@ const SETTINGS_SCHEMA = {
       },
     },
   },
+  output: {
+    type: 'object',
+    label: 'Output',
+    category: 'General',
+    requiresRestart: false,
+    default: {},
+    description: 'Settings for the CLI output.',
+    showInDialog: false,
+    properties: {
+      format: {
+        type: 'enum',
+        label: 'Output Format',
+        category: 'General',
+        requiresRestart: false,
+        default: 'text',
+        description: 'The format of the CLI output.',
+        showInDialog: true,
+        options: [
+          { value: 'text', label: 'Text' },
+          { value: 'json', label: 'JSON' },
+        ],
+      },
+    },
+  },
 
   ui: {
     type: 'object',