feat(core): differentiate User-Agent for a2a-server and ACP clients (#22059)

packages/cli/src/config/config.test.ts

@@ -3616,3 +3616,54 @@ describe('loadCliConfig mcpEnabled', () => {
     });
   });
 });
+
+describe('loadCliConfig acpMode and clientName', () => {
+  beforeEach(() => {
+    vi.resetAllMocks();
+    vi.mocked(os.homedir).mockReturnValue('/mock/home/user');
+    vi.stubEnv('GEMINI_API_KEY', 'test-api-key');
+    vi.spyOn(ExtensionManager.prototype, 'getExtensions').mockReturnValue([]);
+  });
+
+  afterEach(() => {
+    vi.unstubAllEnvs();
+  });
+
+  it('should set acpMode to true and detect clientName when --acp flag is used', async () => {
+    process.argv = ['node', 'script.js', '--acp'];
+    vi.stubEnv('TERM_PROGRAM', 'vscode');
+    const argv = await parseArguments(createTestMergedSettings());
+    const config = await loadCliConfig(
+      createTestMergedSettings(),
+      'test-session',
+      argv,
+    );
+    expect(config.getAcpMode()).toBe(true);
+    expect(config.getClientName()).toBe('acp-vscode');
+  });
+
+  it('should set acpMode to true but leave clientName undefined for generic terminals', async () => {
+    process.argv = ['node', 'script.js', '--acp'];
+    vi.stubEnv('TERM_PROGRAM', 'iTerm.app'); // Generic terminal
+    const argv = await parseArguments(createTestMergedSettings());
+    const config = await loadCliConfig(
+      createTestMergedSettings(),
+      'test-session',
+      argv,
+    );
+    expect(config.getAcpMode()).toBe(true);
+    expect(config.getClientName()).toBeUndefined();
+  });
+
+  it('should set acpMode to false and clientName to undefined by default', async () => {
+    process.argv = ['node', 'script.js'];
+    const argv = await parseArguments(createTestMergedSettings());
+    const config = await loadCliConfig(
+      createTestMergedSettings(),
+      'test-session',
+      argv,
+    );
+    expect(config.getAcpMode()).toBe(false);
+    expect(config.getClientName()).toBeUndefined();
+  });
+});

packages/cli/src/config/config.ts

@@ -40,6 +40,7 @@ import {
   type HookDefinition,
   type HookEventName,
   type OutputFormat,
+  detectIdeFromEnv,
 } from '@google/gemini-cli-core';
 import {
   type Settings,
@@ -710,8 +711,21 @@ export async function loadCliConfig(
     }
   }
 
+  const isAcpMode = !!argv.acp || !!argv.experimentalAcp;
+  let clientName: string | undefined = undefined;
+  if (isAcpMode) {
+    const ide = detectIdeFromEnv();
+    if (
+      ide &&
+      (ide.name !== 'vscode' || process.env['TERM_PROGRAM'] === 'vscode')
+    ) {
+      clientName = `acp-${ide.name}`;
+    }
+  }
+
   return new Config({
-    acpMode: !!argv.acp || !!argv.experimentalAcp,
+    acpMode: isAcpMode,
+    clientName,
     sessionId,
     clientVersion: await getVersion(),
     embeddingModel: DEFAULT_GEMINI_EMBEDDING_MODEL,