add --telemetry-outfile flag (#4689)

packages/core/src/config/config.ts

@@ -73,6 +73,7 @@ export interface TelemetrySettings {
   target?: TelemetryTarget;
   otlpEndpoint?: string;
   logPrompts?: boolean;
+  outfile?: string;
 }
 
 export interface GeminiCLIExtension {
@@ -255,6 +256,7 @@ export class Config {
       target: params.telemetry?.target ?? DEFAULT_TELEMETRY_TARGET,
       otlpEndpoint: params.telemetry?.otlpEndpoint ?? DEFAULT_OTLP_ENDPOINT,
       logPrompts: params.telemetry?.logPrompts ?? true,
+      outfile: params.telemetry?.outfile,
     };
     this.usageStatisticsEnabled = params.usageStatisticsEnabled ?? true;
 
@@ -468,6 +470,10 @@ export class Config {
     return this.telemetrySettings.target ?? DEFAULT_TELEMETRY_TARGET;
   }
 
+  getTelemetryOutfile(): string | undefined {
+    return this.telemetrySettings.outfile;
+  }
+
   getGeminiClient(): GeminiClient {
     return this.geminiClient;
   }