diff --git a/dev/src/cli/cli.ts b/dev/src/cli/cli.ts
index f227c979f..dca7a0bdb 100644
--- a/dev/src/cli/cli.ts
+++ b/dev/src/cli/cli.ts
@@ -14,7 +14,6 @@ import {
   setLogLevel as setAdkCoreLogLevel,
 } from '@google/adk';
 import {Argument, Command, Option} from 'commander';
-import dotenv from 'dotenv';
 import * as path from 'path';
 import {runIntegrationTests} from '../integration/run_integration_tests.js';
 import {AdkApiServer} from '../server/adk_api_server.js';
@@ -27,8 +26,6 @@ import {runAgent} from './cli_run.js';
 import {deployToAgentEngine} from './deploy/cli_deploy_agent_engine.js';
 import {deployToCloudRun} from './deploy/cli_deploy_cloud_run.js';
 
-dotenv.config({quiet: true});
-
 const LOG_LEVEL_MAP: Record<string, LogLevel> = {
   'debug': LogLevel.DEBUG,
   'info': LogLevel.INFO,
diff --git a/dev/src/cli_entrypoint.ts b/dev/src/cli_entrypoint.ts
index 4b354b9a8..e2beeabd0 100644
--- a/dev/src/cli_entrypoint.ts
+++ b/dev/src/cli_entrypoint.ts
@@ -4,9 +4,11 @@
  * Copyright 2026 Google LLC
  * SPDX-License-Identifier: Apache-2.0
  */
+import dotenv from 'dotenv';
 import {createProgram} from './cli/cli.js';
 
 try {
+  dotenv.config({quiet: true});
   createProgram().parse(process.argv);
 } catch (e) {
   console.error(e);
diff --git a/dev/test/cli/cli_test.ts b/dev/test/cli/cli_test.ts
index 75d003802..d4198b1b3 100644
--- a/dev/test/cli/cli_test.ts
+++ b/dev/test/cli/cli_test.ts
@@ -5,6 +5,10 @@
  */
 
 import {LogLevel, setLogLevel} from '@google/adk';
+import dotenv from 'dotenv';
+import * as fs from 'node:fs/promises';
+import * as os from 'node:os';
+import * as path from 'node:path';
 import {afterEach, beforeEach, describe, expect, it, Mock, vi} from 'vitest';
 import {createProgram} from '../../src/cli/cli.js';
 import {createAgent} from '../../src/cli/cli_create.js';
@@ -49,6 +53,9 @@ vi.mock('@google/adk', async (importOriginal) => {
   };
 });
 
+/** Env var no production code reads, so the assertion pins the mechanism. */
+const DOTENV_SENTINEL = 'ADK_DOTENV_IMPORT_SENTINEL';
+
 describe('CLI Entrypoint', () => {
   let program: ReturnType<typeof createProgram>;
 
@@ -415,4 +422,39 @@ describe('CLI Entrypoint', () => {
       });
     });
   });
+
+  describe('module import side effects', () => {
+    let envDir: string;
+
+    beforeEach(async () => {
+      envDir = await fs.mkdtemp(path.join(os.tmpdir(), 'adk-cli-dotenv-'));
+      await fs.writeFile(
+        path.join(envDir, '.env'),
+        `${DOTENV_SENTINEL}=leaked\n`,
+      );
+      // dotenv resolves `${process.cwd()}/.env` at call time, so the spy
+      // redirects the lookup the way a real chdir would.
+      vi.spyOn(process, 'cwd').mockReturnValue(envDir);
+    });
+
+    afterEach(async () => {
+      delete process.env[DOTENV_SENTINEL];
+      await fs.rm(envDir, {recursive: true, force: true});
+    });
+
+    it('should not read a .env file from the working directory on import', async () => {
+      // Without the reset, cli.js is already in the module registry from this
+      // file's static import and would not re-evaluate.
+      vi.resetModules();
+      await import('../../src/cli/cli.js');
+
+      expect(process.env[DOTENV_SENTINEL]).toBeUndefined();
+    });
+
+    it('should still load that .env once dotenv.config runs, as the entrypoint does', () => {
+      dotenv.config({quiet: true});
+
+      expect(process.env[DOTENV_SENTINEL]).toBe('leaked');
+    });
+  });
 });