fix: keep default identity headers User-Agent-only for product boundary

Default outbound headers stay User-Agent only. Tests that required
X-Msh-* on the default path now assert User-Agent instead.

Author: elkaix

packages/agent-gateway/test/boot.test.ts

@@ -131,8 +131,6 @@ describe('server-v2 boot', () => {
     });
     const defaults = server.core.accessor.get(IHostRequestHeaders);
     expect(defaults.headers['User-Agent']).toBe('test-host/0.0.0-test');
-    expect(defaults.headers['X-Msh-Version']).toBe('0.0.0-test');
-    expect(defaults.headers['X-Msh-Platform']).toBe('test_platform');
 
     await server.close();
     server = undefined;

packages/node-sdk/test/sdk-rpc-client-v2.test.ts

@@ -352,9 +352,8 @@ describe('SDKRpcClientV2 (agent-core-v2 wiring)', () => {
       // User-Agent and no X-Msh-*  the interactive-v2 path's identity bug.
       const headers = client.engineAccessor.get(IHostRequestHeaders).headers;
       expect(headers['User-Agent']).toBe(`pythinker-code-cli/${TEST_IDENTITY.version}`);
-      expect(headers['X-Msh-Platform']).toBe('pythinker_code_cli');
-      expect(headers['X-Msh-Version']).toBe(TEST_IDENTITY.version);
-      expect(headers['X-Msh-Device-Id']).toBeTruthy();
+      expect(headers['User-Agent']).toContain('pythinker');
+            expect(headers['X-Msh-Device-Id']).toBeTruthy();
     } finally {
       await client.close();
     }

packages/oauth/src/identity.ts

@@ -104,14 +104,8 @@ export function replaceUserAgentProduct(userAgent: string, product: string): str
  * includes only the product User-Agent.
  */
 export function createPythinkerDefaultHeaders(options: PythinkerIdentityOptions): Record<string, string> {
-  const deviceId =
-    options.deviceId ??
-    (options.homeDir !== undefined ? createPythinkerDeviceId(options.homeDir) : undefined);
   return {
     'User-Agent': createPythinkerUserAgent(options),
-    'X-Msh-Platform': options.platform,
-    'X-Msh-Version': options.version,
-    ...(deviceId !== undefined ? { 'X-Msh-Device-Id': deviceId } : {}),
   };
 }