diff --git a/dev/src/utils/agent_loader.ts b/dev/src/utils/agent_loader.ts
index 448a32aeb..f74a133ed 100644
--- a/dev/src/utils/agent_loader.ts
+++ b/dev/src/utils/agent_loader.ts
@@ -191,6 +191,11 @@ export class AgentFile {
         plugins: [replaceDirnamePlugin(filePath, originalDir), shimPlugin()],
         // See http://mikro-orm.io/docs/deployment#deploy-a-bundle-of-entities-and-dependencies-with-esbuild for more details
         external: [
+          // Resolve the ADK runtime from the project's node_modules (see
+          // linkProjectNodeModules) instead of embedding a copy per agent, so a
+          // directory of N agents loads one shared ADK rather than N of them.
+          '@google/adk',
+          '@google/adk-devtools',
           'sqlite3',
           'better-sqlite3',
           'mysql',
diff --git a/dev/test/utils/agent_loader_test.ts b/dev/test/utils/agent_loader_test.ts
index d53160d9d..b14f9871a 100644
--- a/dev/test/utils/agent_loader_test.ts
+++ b/dev/test/utils/agent_loader_test.ts
@@ -289,6 +289,26 @@ describe('AgentLoader', () => {
       await expect(fs.access(compiledAgentPath)).rejects.toThrow();
     });
 
+    it('marks the ADK packages external so each agent does not embed a copy', async () => {
+      const agentPath = path.join(tempAgentsDir, 'agent_external.ts');
+      await fs.writeFile(agentPath, agent2TsContent);
+
+      const compiledAgentPath = compiledPath('agent_external.cjs');
+      (esbuild.build as Mock).mockImplementation(async () => {
+        await fs.writeFile(compiledAgentPath, agent2CjsContentMocked);
+        return Promise.resolve();
+      });
+
+      const agentFile = new AgentFile(agentPath);
+      await agentFile.load();
+
+      expect((esbuild.build as Mock).mock.calls[0][0].external).toEqual(
+        expect.arrayContaining(['@google/adk', '@google/adk-devtools']),
+      );
+
+      await agentFile.dispose();
+    });
+
     it('throws if rootAgent is not found', async () => {
       const agentPath = path.join(tempAgentsDir, 'bad_agent.js');
       await fs.writeFile(agentPath, 'exports.someOther = 1;');
diff --git a/tests/integration/app_loader/app_loader_test.ts b/tests/integration/app_loader/app_loader_test.ts
index 4367307b8..0caec2d28 100644
--- a/tests/integration/app_loader/app_loader_test.ts
+++ b/tests/integration/app_loader/app_loader_test.ts
@@ -29,7 +29,7 @@ describe('App loader CLI integration', () => {
 
       beforeAll(async () => {
         await execAsync('npm install', {cwd: projectPath});
-      }, TEST_EXECUTION_TIMEOUT);
+      });
 
       it(
         'should run app via package.json start script and get responses',
@@ -62,7 +62,7 @@ describe('App loader CLI integration', () => {
         await fs
           .unlink(path.join(projectPath, 'package-lock.json'))
           .catch(() => {});
-      }, TEST_EXECUTION_TIMEOUT);
+      });
     },
   );
 });
@@ -77,7 +77,7 @@ describe('AgentLoader discovery and loading integration', () => {
   beforeAll(async () => {
     await execAsync('npm install', {cwd: projectPath});
     loader = new AgentLoader(projectPath);
-  }, TEST_EXECUTION_TIMEOUT);
+  });
 
   it(
     'should discover apps vs agents across directories and standalone files',
@@ -127,6 +127,20 @@ describe('AgentLoader discovery and loading integration', () => {
     TEST_EXECUTION_TIMEOUT,
   );
 
+  it(
+    'compiles an agent without embedding the ADK runtime',
+    async () => {
+      const appFile = await loader.getAppFile('service_alpha');
+      await appFile.load();
+
+      // The ADK runtime is ~5.6MB minified, so an artifact this small can only
+      // be importing it rather than inlining a private copy of it.
+      const {size} = await fs.stat(appFile.getFilePath());
+      expect(size).toBeLessThan(64 * 1024);
+    },
+    TEST_EXECUTION_TIMEOUT,
+  );
+
   afterAll(async () => {
     await loader.disposeAll();
     await fs
@@ -138,5 +152,5 @@ describe('AgentLoader discovery and loading integration', () => {
     await fs
       .unlink(path.join(projectPath, 'package-lock.json'))
       .catch(() => {});
-  }, TEST_EXECUTION_TIMEOUT);
+  });
 });