Add telemetry command and refactor telemetry settings (#1060)

#750 

### Telemetry Settings
Refactors telemetry configuration to use a nested `telemetry` object in `settings.json`, for example:

```json
{
  "telemetry": {
    "enabled": true,
    "target": "gcp"
    "log-prompts": "true"
  },
  "sandbox": false
}
```

The above includes
- Centralized telemetry settings under a `telemetry` object in `settings.json`.
- CLI flags for the `gemini` command to override all telemetry sub-settings:
    - `--telemetry` / `--no-telemetry`
    - `--telemetry-target <local|gcp>`
    - `--telemetry-otlp-endpoint <URL>`
    - `--telemetry-log-prompts` / `--no-telemetry-log-prompts`
- Updates `packages/cli/src/config/config.ts` and `packages/core/src/config/config.ts` to read from the new settings structure and respect the new CLI flags.
- Modifies `scripts/handle-telemetry.js`, `scripts/local_telemetry.js`, and `scripts/telemetry_utils.js` to align with the new settings structure.
- Updates `docs/core/telemetry.md` to reflect the new settings structure, CLI flags, and order of precedence.
- Renames `logUserPromptsEnabled` to `logPrompts` for brevity.

### `npm run telemetry`

Add a new `npm run telemetry` command that uses `scripts/telemetry.js`, automates the entire process of setting up a local and GCP telemetry pipelines, including configuring the necessary settings in the `.gemini/settings.json` workspace file and installing required binaries (e.g. `otelcol-contrib`).

---
```shell
$ npm run telemetry -- --target=gcp

> [email protected] telemetry
> node scripts/telemetry.js --target=gcp

⚙️  Using command-line target: gcp
🚀 Running telemetry script for target: gcp.
✨ Starting Local Telemetry Exporter for Google Cloud ✨
⚙️  Enabled telemetry in workspace settings.
🔧 Set telemetry OTLP endpoint to http://localhost:4317.
🎯 Set telemetry target to gcp.
✅ Workspace settings updated.
✅ Using Google Cloud Project ID: foo-bar

🔑 Please ensure you are authenticated with Google Cloud:
  - Run `gcloud auth application-default login` OR ensure `GOOGLE_APPLICATION_CREDENTIALS` environment variable points to a valid service account key.
  - The account needs "Cloud Trace Agent", "Monitoring Metric Writer", and "Logs Writer" roles.
✅ otelcol-contrib already exists at /Users/jerop/github/gemini-cli/.gemini/otel/bin/otelcol-contrib
🧹 Cleaning up old processes and logs...
✅ Deleted old GCP collector log.
📄 Wrote OTEL collector config to /Users/jerop/github/gemini-cli/.gemini/otel/collector-gcp.yaml
🚀 Starting OTEL collector for GCP... Logs: /Users/jerop/github/gemini-cli/.gemini/otel/collector-gcp.log
⏳ Waiting for OTEL collector to start (PID: 17013)...
✅ OTEL collector started successfully on port 4317.

✨ Local OTEL collector for GCP is running.

🚀 To send telemetry, run the Gemini CLI in a separate terminal window.

📄 Collector logs are being written to: /Users/jerop/github/gemini-cli/.gemini/otel/collector-gcp.log

📊 View your telemetry data in Google Cloud Console:
   - Logs: https://console.cloud.google.com/logs/query;query=logName%3D%22projects%2Ffoo-bar%2Flogs%2Fgemini_cli%22?project=foo-bar
   - Metrics: https://console.cloud.google.com/monitoring/metrics-explorer?project=foo-bar
   - Traces: https://console.cloud.google.com/traces/list?project=foo-bar

Press Ctrl+C to exit.
^C
👋 Shutting down...
⚙️  Disabled telemetry in workspace settings.
🔧 Cleared telemetry OTLP endpoint.
🎯 Cleared telemetry target.
✅ Workspace settings updated.
🛑 Stopping otelcol-contrib (PID: 17013)...
✅ otelcol-contrib stopped.
```

7 files changed, 133 insertions, 29 deletions

diff --git a/packages/core/src/config/config.test.ts b/packages/core/src/config/config.test.ts
index ea555bd4..e8f56f75 100644
--- a/packages/core/src/config/config.test.ts
+++ b/packages/core/src/config/config.test.ts
@@ -8,6 +8,10 @@ import { describe, it, expect, vi, beforeEach } from 'vitest';
 import { Config, ConfigParameters } from './config.js';
 import * as path from 'path';
 import { setGeminiMdFilename as mockSetGeminiMdFilename } from '../tools/memoryTool.js';
+import {
+  DEFAULT_TELEMETRY_TARGET,
+  DEFAULT_OTLP_ENDPOINT,
+} from '../telemetry/index.js';
 
 // Mock dependencies that might be called during Config construction or createServerConfig
 vi.mock('../tools/tool-registry', () => {
@@ -38,6 +42,14 @@ vi.mock('../tools/memoryTool', () => ({
   GEMINI_CONFIG_DIR: '.gemini',
 }));
 
+vi.mock('../telemetry/index.js', async (importOriginal) => {
+  const actual = await importOriginal<typeof import('../telemetry/index.js')>();
+  return {
+    ...actual,
+    initializeTelemetry: vi.fn(),
+  };
+});
+
 describe('Server Config (config.ts)', () => {
   const API_KEY = 'server-api-key';
   const MODEL = 'gemini-pro';
@@ -47,7 +59,7 @@ describe('Server Config (config.ts)', () => {
   const QUESTION = 'test question';
   const FULL_CONTEXT = false;
   const USER_MEMORY = 'Test User Memory';
-  const TELEMETRY = false;
+  const TELEMETRY_SETTINGS = { enabled: false };
   const EMBEDDING_MODEL = 'gemini-embedding';
   const SESSION_ID = 'test-session-id';
   const baseParams: ConfigParameters = {
@@ -63,7 +75,7 @@ describe('Server Config (config.ts)', () => {
     question: QUESTION,
     fullContext: FULL_CONTEXT,
     userMemory: USER_MEMORY,
-    telemetry: TELEMETRY,
+    telemetry: TELEMETRY_SETTINGS,
     sessionId: SESSION_ID,
   };
 
@@ -120,7 +132,7 @@ describe('Server Config (config.ts)', () => {
   it('Config constructor should set telemetry to true when provided as true', () => {
     const paramsWithTelemetry: ConfigParameters = {
       ...baseParams,
-      telemetry: true,
+      telemetry: { enabled: true },
     };
     const config = new Config(paramsWithTelemetry);
     expect(config.getTelemetryEnabled()).toBe(true);
@@ -129,7 +141,7 @@ describe('Server Config (config.ts)', () => {
   it('Config constructor should set telemetry to false when provided as false', () => {
     const paramsWithTelemetry: ConfigParameters = {
       ...baseParams,
-      telemetry: false,
+      telemetry: { enabled: false },
     };
     const config = new Config(paramsWithTelemetry);
     expect(config.getTelemetryEnabled()).toBe(false);
@@ -139,7 +151,7 @@ describe('Server Config (config.ts)', () => {
     const paramsWithoutTelemetry: ConfigParameters = { ...baseParams };
     delete paramsWithoutTelemetry.telemetry;
     const config = new Config(paramsWithoutTelemetry);
-    expect(config.getTelemetryEnabled()).toBe(TELEMETRY);
+    expect(config.getTelemetryEnabled()).toBe(TELEMETRY_SETTINGS.enabled);
   });
 
   it('should have a getFileService method that returns FileDiscoveryService', () => {
@@ -147,4 +159,73 @@ describe('Server Config (config.ts)', () => {
     const fileService = config.getFileService();
     expect(fileService).toBeDefined();
   });
+
+  describe('Telemetry Settings', () => {
+    it('should return default telemetry target if not provided', () => {
+      const params: ConfigParameters = {
+        ...baseParams,
+        telemetry: { enabled: true },
+      };
+      const config = new Config(params);
+      expect(config.getTelemetryTarget()).toBe(DEFAULT_TELEMETRY_TARGET);
+    });
+
+    it('should return provided OTLP endpoint', () => {
+      const endpoint = 'http://custom.otel.collector:4317';
+      const params: ConfigParameters = {
+        ...baseParams,
+        telemetry: { enabled: true, otlpEndpoint: endpoint },
+      };
+      const config = new Config(params);
+      expect(config.getTelemetryOtlpEndpoint()).toBe(endpoint);
+    });
+
+    it('should return default OTLP endpoint if not provided', () => {
+      const params: ConfigParameters = {
+        ...baseParams,
+        telemetry: { enabled: true },
+      };
+      const config = new Config(params);
+      expect(config.getTelemetryOtlpEndpoint()).toBe(DEFAULT_OTLP_ENDPOINT);
+    });
+
+    it('should return provided logPrompts setting', () => {
+      const params: ConfigParameters = {
+        ...baseParams,
+        telemetry: { enabled: true, logPrompts: false },
+      };
+      const config = new Config(params);
+      expect(config.getTelemetryLogPromptsEnabled()).toBe(false);
+    });
+
+    it('should return default logPrompts setting (true) if not provided', () => {
+      const params: ConfigParameters = {
+        ...baseParams,
+        telemetry: { enabled: true },
+      };
+      const config = new Config(params);
+      expect(config.getTelemetryLogPromptsEnabled()).toBe(true);
+    });
+
+    it('should return default logPrompts setting (true) if telemetry object is not provided', () => {
+      const paramsWithoutTelemetry: ConfigParameters = { ...baseParams };
+      delete paramsWithoutTelemetry.telemetry;
+      const config = new Config(paramsWithoutTelemetry);
+      expect(config.getTelemetryLogPromptsEnabled()).toBe(true);
+    });
+
+    it('should return default telemetry target if telemetry object is not provided', () => {
+      const paramsWithoutTelemetry: ConfigParameters = { ...baseParams };
+      delete paramsWithoutTelemetry.telemetry;
+      const config = new Config(paramsWithoutTelemetry);
+      expect(config.getTelemetryTarget()).toBe(DEFAULT_TELEMETRY_TARGET);
+    });
+
+    it('should return default OTLP endpoint if telemetry object is not provided', () => {
+      const paramsWithoutTelemetry: ConfigParameters = { ...baseParams };
+      delete paramsWithoutTelemetry.telemetry;
+      const config = new Config(paramsWithoutTelemetry);
+      expect(config.getTelemetryOtlpEndpoint()).toBe(DEFAULT_OTLP_ENDPOINT);
+    });
+  });
 });
diff --git a/packages/core/src/config/config.ts b/packages/core/src/config/config.ts
index d841f4b3..891b6302 100644
--- a/packages/core/src/config/config.ts
+++ b/packages/core/src/config/config.ts
@@ -23,7 +23,12 @@ import { GeminiClient } from '../core/client.js';
 import { GEMINI_CONFIG_DIR as GEMINI_DIR } from '../tools/memoryTool.js';
 import { FileDiscoveryService } from '../services/fileDiscoveryService.js';
 import { GitService } from '../services/gitService.js';
-import { initializeTelemetry } from '../telemetry/index.js';
+import {
+  initializeTelemetry,
+  DEFAULT_TELEMETRY_TARGET,
+  DEFAULT_OTLP_ENDPOINT,
+  TelemetryTarget,
+} from '../telemetry/index.js';
 import { DEFAULT_GEMINI_EMBEDDING_MODEL } from './models.js';
 
 export enum ApprovalMode {
@@ -40,6 +45,13 @@ export interface BugCommandSettings {
   urlTemplate: string;
 }
 
+export interface TelemetrySettings {
+  enabled?: boolean;
+  target?: TelemetryTarget;
+  otlpEndpoint?: string;
+  logPrompts?: boolean;
+}
+
 export class MCPServerConfig {
   constructor(
     // For stdio transport
@@ -82,9 +94,7 @@ export interface ConfigParameters {
   showMemoryUsage?: boolean;
   contextFileName?: string | string[];
   accessibility?: AccessibilitySettings;
-  telemetry?: boolean;
-  telemetryLogUserPromptsEnabled?: boolean;
-  telemetryOtlpEndpoint?: string;
+  telemetry?: TelemetrySettings;
   fileFilteringRespectGitIgnore?: boolean;
   checkpoint?: boolean;
   proxy?: string;
@@ -114,9 +124,7 @@ export class Config {
   private approvalMode: ApprovalMode;
   private readonly showMemoryUsage: boolean;
   private readonly accessibility: AccessibilitySettings;
-  private readonly telemetry: boolean;
-  private readonly telemetryLogUserPromptsEnabled: boolean;
-  private readonly telemetryOtlpEndpoint: string;
+  private readonly telemetrySettings: TelemetrySettings;
   private readonly geminiClient: GeminiClient;
   private readonly fileFilteringRespectGitIgnore: boolean;
   private fileDiscoveryService: FileDiscoveryService | null = null;
@@ -147,11 +155,13 @@ export class Config {
     this.approvalMode = params.approvalMode ?? ApprovalMode.DEFAULT;
     this.showMemoryUsage = params.showMemoryUsage ?? false;
     this.accessibility = params.accessibility ?? {};
-    this.telemetry = params.telemetry ?? false;
-    this.telemetryLogUserPromptsEnabled =
-      params.telemetryLogUserPromptsEnabled ?? true;
-    this.telemetryOtlpEndpoint =
-      params.telemetryOtlpEndpoint ?? 'http://localhost:4317';
+    this.telemetrySettings = {
+      enabled: params.telemetry?.enabled ?? false,
+      target: params.telemetry?.target ?? DEFAULT_TELEMETRY_TARGET,
+      otlpEndpoint: params.telemetry?.otlpEndpoint ?? DEFAULT_OTLP_ENDPOINT,
+      logPrompts: params.telemetry?.logPrompts ?? true,
+    };
+
     this.fileFilteringRespectGitIgnore =
       params.fileFilteringRespectGitIgnore ?? true;
     this.checkpoint = params.checkpoint ?? false;
@@ -167,7 +177,7 @@ export class Config {
     this.toolRegistry = createToolRegistry(this);
     this.geminiClient = new GeminiClient(this);
 
-    if (this.telemetry) {
+    if (this.telemetrySettings.enabled) {
       initializeTelemetry(this);
     }
   }
@@ -272,15 +282,19 @@ export class Config {
   }
 
   getTelemetryEnabled(): boolean {
-    return this.telemetry;
+    return this.telemetrySettings.enabled ?? false;
   }
 
-  getTelemetryLogUserPromptsEnabled(): boolean {
-    return this.telemetryLogUserPromptsEnabled;
+  getTelemetryLogPromptsEnabled(): boolean {
+    return this.telemetrySettings.logPrompts ?? true;
   }
 
   getTelemetryOtlpEndpoint(): string {
-    return this.telemetryOtlpEndpoint;
+    return this.telemetrySettings.otlpEndpoint ?? DEFAULT_OTLP_ENDPOINT;
+  }
+
+  getTelemetryTarget(): TelemetryTarget {
+    return this.telemetrySettings.target ?? DEFAULT_TELEMETRY_TARGET;
   }
 
   getGeminiClient(): GeminiClient {
diff --git a/packages/core/src/core/geminiChat.test.ts b/packages/core/src/core/geminiChat.test.ts
index 24a7279d..9961103d 100644
--- a/packages/core/src/core/geminiChat.test.ts
+++ b/packages/core/src/core/geminiChat.test.ts
@@ -26,7 +26,7 @@ const mockModelsModule = {
 
 const mockConfig = {
   getSessionId: () => 'test-session-id',
-  getTelemetryLogUserPromptsEnabled: () => true,
+  getTelemetryLogPromptsEnabled: () => true,
 } as unknown as Config;
 
 describe('GeminiChat', () => {
diff --git a/packages/core/src/core/geminiChat.ts b/packages/core/src/core/geminiChat.ts
index eb740c4a..1268e8c2 100644
--- a/packages/core/src/core/geminiChat.ts
+++ b/packages/core/src/core/geminiChat.ts
@@ -153,7 +153,7 @@ export class GeminiChat {
     model: string,
   ): Promise<void> {
     const shouldLogUserPrompts = (config: Config): boolean =>
-      config.getTelemetryLogUserPromptsEnabled() ?? false;
+      config.getTelemetryLogPromptsEnabled() ?? false;
 
     const requestText = this._getRequestTextFromContents(contents);
     logApiRequest(this.config, {
diff --git a/packages/core/src/telemetry/index.ts b/packages/core/src/telemetry/index.ts
index e8248bf9..32e98144 100644
--- a/packages/core/src/telemetry/index.ts
+++ b/packages/core/src/telemetry/index.ts
@@ -4,6 +4,15 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+export enum TelemetryTarget {
+  GCP = 'gcp',
+  LOCAL = 'local',
+}
+
+const DEFAULT_TELEMETRY_TARGET = TelemetryTarget.LOCAL;
+const DEFAULT_OTLP_ENDPOINT = 'http://localhost:4317';
+
+export { DEFAULT_TELEMETRY_TARGET, DEFAULT_OTLP_ENDPOINT };
 export {
   initializeTelemetry,
   shutdownTelemetry,
diff --git a/packages/core/src/telemetry/loggers.test.ts b/packages/core/src/telemetry/loggers.test.ts
index 2f909c22..6ec73853 100644
--- a/packages/core/src/telemetry/loggers.test.ts
+++ b/packages/core/src/telemetry/loggers.test.ts
@@ -60,7 +60,7 @@ describe('loggers', () => {
           vertexai: true,
           codeAssist: false,
         }),
-        getTelemetryLogUserPromptsEnabled: () => true,
+        getTelemetryLogPromptsEnabled: () => true,
         getFileFilteringRespectGitIgnore: () => true,
         getDebugMode: () => true,
         getMcpServers: () => ({
@@ -99,7 +99,7 @@ describe('loggers', () => {
   describe('logUserPrompt', () => {
     const mockConfig = {
       getSessionId: () => 'test-session-id',
-      getTelemetryLogUserPromptsEnabled: () => true,
+      getTelemetryLogPromptsEnabled: () => true,
     } as unknown as Config;
 
     it('should log a user prompt', () => {
@@ -125,7 +125,7 @@ describe('loggers', () => {
     it('should not log prompt if disabled', () => {
       const mockConfig = {
         getSessionId: () => 'test-session-id',
-        getTelemetryLogUserPromptsEnabled: () => false,
+        getTelemetryLogPromptsEnabled: () => false,
       } as unknown as Config;
       const event = {
         prompt: 'test-prompt',
diff --git a/packages/core/src/telemetry/loggers.ts b/packages/core/src/telemetry/loggers.ts
index e788119c..01e83908 100644
--- a/packages/core/src/telemetry/loggers.ts
+++ b/packages/core/src/telemetry/loggers.ts
@@ -37,7 +37,7 @@ import {
 } from '@google/genai';
 
 const shouldLogUserPrompts = (config: Config): boolean =>
-  config.getTelemetryLogUserPromptsEnabled() ?? false;
+  config.getTelemetryLogPromptsEnabled() ?? false;
 
 function getCommonAttributes(config: Config): LogAttributes {
   return {
@@ -86,7 +86,7 @@ export function logCliConfiguration(config: Config): void {
     api_key_enabled: !!generatorConfig.apiKey,
     vertex_ai_enabled: !!generatorConfig.vertexai,
     code_assist_enabled: !!generatorConfig.codeAssist,
-    log_user_prompts_enabled: config.getTelemetryLogUserPromptsEnabled(),
+    log_user_prompts_enabled: config.getTelemetryLogPromptsEnabled(),
     file_filtering_respect_git_ignore:
       config.getFileFilteringRespectGitIgnore(),
     debug_mode: config.getDebugMode(),