fix(telemetry): disable OTLP when telemetry-outfile is set (#9117)

docs/telemetry.md

@@ -52,12 +52,12 @@ All telemetry behavior is controlled through your `.gemini/settings.json` file
 and can be overridden with CLI flags:
 
 | Setting        | Values            | Default                 | CLI Override                                             | Description                                       |
-| -------------- | ----------------- | ----------------------- | -------------------------------------------------------- | ---------------------------------------------------- |
+| -------------- | ----------------- | ----------------------- | -------------------------------------------------------- | ------------------------------------------------- |
 | `enabled`      | `true`/`false`    | `false`                 | `--telemetry` / `--no-telemetry`                         | Enable or disable telemetry                       |
 | `target`       | `"gcp"`/`"local"` | `"local"`               | `--telemetry-target <local\|gcp>`                        | Where to send telemetry data                      |
 | `otlpEndpoint` | URL string        | `http://localhost:4317` | `--telemetry-otlp-endpoint <URL>`                        | OTLP collector endpoint                           |
 | `otlpProtocol` | `"grpc"`/`"http"` | `"grpc"`                | `--telemetry-otlp-protocol <grpc\|http>`                 | OTLP transport protocol                           |
-| `outfile`      | file path         | -                       | `--telemetry-outfile <path>`                             | Save telemetry to file (requires `otlpEndpoint: ""`) |
+| `outfile`      | file path         | -                       | `--telemetry-outfile <path>`                             | Save telemetry to file (overrides `otlpEndpoint`) |
 | `logPrompts`   | `true`/`false`    | `true`                  | `--telemetry-log-prompts` / `--no-telemetry-log-prompts` | Include prompts in telemetry logs                 |
 | `useCollector` | `true`/`false`    | `false`                 | -                                                        | Use external OTLP collector (advanced)            |
 

packages/core/src/telemetry/sdk.test.ts

@@ -21,6 +21,9 @@ import {
 } from './gcp-exporters.js';
 import { TelemetryTarget } from './index.js';
 
+import * as os from 'node:os';
+import * as path from 'node:path';
+
 vi.mock('@opentelemetry/exporter-trace-otlp-grpc');
 vi.mock('@opentelemetry/exporter-logs-otlp-grpc');
 vi.mock('@opentelemetry/exporter-metrics-otlp-grpc');
@@ -218,4 +221,19 @@ describe('Telemetry SDK', () => {
       }
     }
   });
+
+  it('should not use OTLP exporters when telemetryOutfile is set', () => {
+    vi.spyOn(mockConfig, 'getTelemetryOutfile').mockReturnValue(
+      path.join(os.tmpdir(), 'test.log'),
+    );
+    initializeTelemetry(mockConfig);
+
+    expect(OTLPTraceExporter).not.toHaveBeenCalled();
+    expect(OTLPLogExporter).not.toHaveBeenCalled();
+    expect(OTLPMetricExporter).not.toHaveBeenCalled();
+    expect(OTLPTraceExporterHttp).not.toHaveBeenCalled();
+    expect(OTLPLogExporterHttp).not.toHaveBeenCalled();
+    expect(OTLPMetricExporterHttp).not.toHaveBeenCalled();
+    expect(NodeSDK.prototype.start).toHaveBeenCalled();
+  });
 });

packages/core/src/telemetry/sdk.ts

@@ -95,8 +95,8 @@ export function initializeTelemetry(config: Config): void {
   const telemetryTarget = config.getTelemetryTarget();
   const useCollector = config.getTelemetryUseCollector();
   const parsedEndpoint = parseOtlpEndpoint(otlpEndpoint, otlpProtocol);
-  const useOtlp = !!parsedEndpoint;
   const telemetryOutfile = config.getTelemetryOutfile();
+  const useOtlp = !!parsedEndpoint && !telemetryOutfile;
 
   const gcpProjectId =
     process.env['OTLP_GOOGLE_CLOUD_PROJECT'] ||