diff --git a/core/build.js b/core/build.js
index 99d01f9d7..f05af70eb 100644
--- a/core/build.js
+++ b/core/build.js
@@ -12,10 +12,10 @@ const platformBuildTargets = {
 };
 
 const licenseHeaderText = `/**
-  * @license
-  * Copyright 2026 Google LLC
-  * SPDX-License-Identifier: Apache-2.0
-  */
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
 `;
 
 /**
diff --git a/dev/build.js b/dev/build.js
index 1cd9db7b0..ee87e457f 100644
--- a/dev/build.js
+++ b/dev/build.js
@@ -22,10 +22,10 @@ const cacheDir = path.join(__dirname, '.cache');
 const zipCachePath = path.join(cacheDir, `adk-web-${ADK_WEB_VERSION}.zip`);
 
 const licenseHeaderText = `/**
-  * @license
-  * Copyright 2026 Google LLC
-  * SPDX-License-Identifier: Apache-2.0
-  */
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
 `;
 
 const commonOptions = {
diff --git a/integrations/build.js b/integrations/build.js
index d07ba5194..ba071167d 100644
--- a/integrations/build.js
+++ b/integrations/build.js
@@ -12,10 +12,10 @@ const platformBuildTargets = {
 };
 
 const licenseHeaderText = `/**
-  * @license
-  * Copyright 2026 Google LLC
-  * SPDX-License-Identifier: Apache-2.0
-  */
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
 `;
 
 /**
diff --git a/tests/integration/build_scripts/license_header_test.ts b/tests/integration/build_scripts/license_header_test.ts
new file mode 100644
index 000000000..b8c211aca
--- /dev/null
+++ b/tests/integration/build_scripts/license_header_test.ts
@@ -0,0 +1,46 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {readFile} from 'node:fs/promises';
+import path from 'node:path';
+import {describe, expect, it} from 'vitest';
+
+const dirname = process.cwd();
+
+/**
+ * The canonical Apache-2.0 header, anchored to the whole string and exact about
+ * whitespace. This mirrors the perl pattern in `scripts/check_license.sh`,
+ * which is the source of truth for the header shape. A bash CI script cannot
+ * read a TypeScript constant, so the pattern is duplicated rather than shared.
+ */
+const CANONICAL_HEADER =
+  /^\/\*\*\n \* @license\n \* Copyright \d{4} Google LLC\n \* SPDX-License-Identifier: Apache-2\.0\n \*\/\n$/;
+
+const LICENSE_HEADER_TEXT = /const licenseHeaderText = `([\s\S]*?)`;/;
+
+const BUILD_SCRIPTS = [
+  'core/build.js',
+  'dev/build.js',
+  'integrations/build.js',
+];
+
+describe('Build script license banner', () => {
+  it.each(BUILD_SCRIPTS)(
+    '%s defines the canonical Apache-2.0 header',
+    async (buildScript: string) => {
+      const source = await readFile(path.join(dirname, buildScript), 'utf8');
+      // Git checks the build scripts out with CRLF on Windows. The assertion
+      // is about the indentation, not the line terminator.
+      const match = LICENSE_HEADER_TEXT.exec(source.replaceAll('\r\n', '\n'));
+
+      if (match === null) {
+        expect.fail(`${buildScript} does not define licenseHeaderText`);
+      }
+
+      expect(match[1]).toMatch(CANONICAL_HEADER);
+    },
+  );
+});