diff --git a/.changeset/fix-macos-device-version.md b/.changeset/fix-macos-device-version.md
new file mode 100644
index 0000000..a6bd431
--- /dev/null
+++ b/.changeset/fix-macos-device-version.md
@@ -0,0 +1,6 @@
+---
+"@moonshot-ai/kimi-code": patch
+"@moonshot-ai/kimi-code-sdk": patch
+---
+
+Report the macOS product version in OAuth device information instead of the Darwin kernel version.
diff --git a/packages/oauth/src/identity.ts b/packages/oauth/src/identity.ts
index 82a22da..aa54e16 100644
--- a/packages/oauth/src/identity.ts
+++ b/packages/oauth/src/identity.ts
@@ -7,6 +7,7 @@
  * production state.
  */
 
+import { execFileSync } from 'node:child_process';
 import { randomUUID } from 'node:crypto';
 import { existsSync, mkdirSync, readFileSync, writeFileSync } from 'node:fs';
 import { arch, hostname, release, type } from 'node:os';
@@ -111,11 +112,23 @@ function deviceModel(): string {
   const os = type();
   const version = release();
   const osArch = arch();
-  if (os === 'Darwin') return `macOS ${version} ${osArch}`;
+  if (os === 'Darwin') return `macOS ${macOsProductVersion() ?? version} ${osArch}`;
   if (os === 'Windows_NT') return `Windows ${version} ${osArch}`;
   return `${os} ${version} ${osArch}`.trim();
 }
 
+function macOsProductVersion(): string | undefined {
+  try {
+    const version = execFileSync('/usr/bin/sw_vers', ['-productVersion'], {
+      encoding: 'utf-8',
+      timeout: 1000,
+    }).trim();
+    return version.length > 0 ? version : undefined;
+  } catch {
+    return undefined;
+  }
+}
+
 function asciiHeader(value: string, fallback = 'unknown'): string {
   const cleaned = value.replaceAll(/[^\u0020-\u007E]/g, '').trim();
   return cleaned.length > 0 ? cleaned : fallback;
diff --git a/packages/oauth/test/identity.test.ts b/packages/oauth/test/identity.test.ts
index f33a9b9..493c1f2 100644
--- a/packages/oauth/test/identity.test.ts
+++ b/packages/oauth/test/identity.test.ts
@@ -147,4 +147,33 @@ describe('ascii header value sanitization', () => {
       vi.resetModules();
     }
   });
+
+  it('falls back to Darwin kernel version when sw_vers is unavailable', async () => {
+    vi.resetModules();
+    vi.doMock('node:os', async () => ({
+      ...(await vi.importActual<typeof import('node:os')>('node:os')),
+      hostname: () => 'my-mac',
+      release: () => '25.5.0',
+      type: () => 'Darwin',
+      arch: () => 'arm64',
+    }));
+    // Force the sw_vers lookup to fail so the test is deterministic on macOS too,
+    // where the real binary would otherwise return the host's product version.
+    vi.doMock('node:child_process', async () => ({
+      ...(await vi.importActual<typeof import('node:child_process')>('node:child_process')),
+      execFileSync: () => {
+        throw new Error('ENOENT');
+      },
+    }));
+
+    try {
+      const { createKimiDeviceHeaders } = await import('../src/identity');
+      const headers = createKimiDeviceHeaders({ homeDir: tempHome(), version: '1.0.0' });
+      expect(headers['X-Msh-Device-Model']).toBe('macOS 25.5.0 arm64');
+    } finally {
+      vi.doUnmock('node:os');
+      vi.doUnmock('node:child_process');
+      vi.resetModules();
+    }
+  });
 });