feat(a2a): add agent acknowledgment command and enhance registry discovery (#22389)

packages/a2a-server/src/config/config.test.ts

@@ -19,6 +19,8 @@ import {
   AuthType,
   isHeadlessMode,
   FatalAuthenticationError,
+  PolicyDecision,
+  PRIORITY_YOLO_ALLOW_ALL,
 } from '@google/gemini-cli-core';
 
 // Mock dependencies
@@ -325,6 +327,29 @@ describe('loadConfig', () => {
       );
     });
 
+    it('should pass enableAgents to Config constructor', async () => {
+      const settings: Settings = {
+        experimental: {
+          enableAgents: false,
+        },
+      };
+      await loadConfig(settings, mockExtensionLoader, taskId);
+      expect(Config).toHaveBeenCalledWith(
+        expect.objectContaining({
+          enableAgents: false,
+        }),
+      );
+    });
+
+    it('should default enableAgents to true when not provided', async () => {
+      await loadConfig(mockSettings, mockExtensionLoader, taskId);
+      expect(Config).toHaveBeenCalledWith(
+        expect.objectContaining({
+          enableAgents: true,
+        }),
+      );
+    });
+
     describe('interactivity', () => {
       it('should set interactive true when not headless', async () => {
         vi.mocked(isHeadlessMode).mockReturnValue(false);
@@ -349,6 +374,41 @@ describe('loadConfig', () => {
       });
     });
 
+    describe('YOLO mode', () => {
+      it('should enable YOLO mode and add policy rule when GEMINI_YOLO_MODE is true', async () => {
+        vi.stubEnv('GEMINI_YOLO_MODE', 'true');
+        await loadConfig(mockSettings, mockExtensionLoader, taskId);
+        expect(Config).toHaveBeenCalledWith(
+          expect.objectContaining({
+            approvalMode: 'yolo',
+            policyEngineConfig: expect.objectContaining({
+              rules: expect.arrayContaining([
+                expect.objectContaining({
+                  decision: PolicyDecision.ALLOW,
+                  priority: PRIORITY_YOLO_ALLOW_ALL,
+                  modes: ['yolo'],
+                  allowRedirection: true,
+                }),
+              ]),
+            }),
+          }),
+        );
+      });
+
+      it('should use default approval mode and empty rules when GEMINI_YOLO_MODE is not true', async () => {
+        vi.stubEnv('GEMINI_YOLO_MODE', 'false');
+        await loadConfig(mockSettings, mockExtensionLoader, taskId);
+        expect(Config).toHaveBeenCalledWith(
+          expect.objectContaining({
+            approvalMode: 'default',
+            policyEngineConfig: expect.objectContaining({
+              rules: [],
+            }),
+          }),
+        );
+      });
+    });
+
     describe('authentication fallback', () => {
       beforeEach(() => {
         vi.stubEnv('USE_CCPA', 'true');

packages/a2a-server/src/config/config.ts

@@ -26,6 +26,8 @@ import {
   isHeadlessMode,
   FatalAuthenticationError,
   isCloudShell,
+  PolicyDecision,
+  PRIORITY_YOLO_ALLOW_ALL,
   type TelemetryTarget,
   type ConfigParameters,
   type ExtensionLoader,
@@ -60,6 +62,11 @@ export async function loadConfig(
     }
   }
 
+  const approvalMode =
+    process.env['GEMINI_YOLO_MODE'] === 'true'
+      ? ApprovalMode.YOLO
+      : ApprovalMode.DEFAULT;
+
   const configParams: ConfigParameters = {
     sessionId: taskId,
     clientName: 'a2a-server',
@@ -74,10 +81,20 @@ export async function loadConfig(
     excludeTools: settings.excludeTools || settings.tools?.exclude || undefined,
     allowedTools: settings.allowedTools || settings.tools?.allowed || undefined,
     showMemoryUsage: settings.showMemoryUsage || false,
-    approvalMode:
+    approvalMode,
-      process.env['GEMINI_YOLO_MODE'] === 'true'
+    policyEngineConfig: {
-        ? ApprovalMode.YOLO
+      rules:
-        : ApprovalMode.DEFAULT,
+        approvalMode === ApprovalMode.YOLO
+          ? [
+              {
+                decision: PolicyDecision.ALLOW,
+                priority: PRIORITY_YOLO_ALLOW_ALL,
+                modes: [ApprovalMode.YOLO],
+                allowRedirection: true,
+              },
+            ]
+          : [],
+    },
     mcpServers: settings.mcpServers,
     cwd: workspaceDir,
     telemetry: {
@@ -110,6 +127,7 @@ export async function loadConfig(
     interactive: !isHeadlessMode(),
     enableInteractiveShell: !isHeadlessMode(),
     ptyInfo: 'auto',
+    enableAgents: settings.experimental?.enableAgents ?? true,
   };
 
   const fileService = new FileDiscoveryService(workspaceDir, {

packages/a2a-server/src/config/settings.test.ts

@@ -112,6 +112,18 @@ describe('loadSettings', () => {
     expect(result.fileFiltering?.respectGitIgnore).toBe(true);
   });
 
+  it('should load experimental settings correctly', () => {
+    const settings = {
+      experimental: {
+        enableAgents: true,
+      },
+    };
+    fs.writeFileSync(USER_SETTINGS_PATH, JSON.stringify(settings));
+
+    const result = loadSettings(mockWorkspaceDir);
+    expect(result.experimental?.enableAgents).toBe(true);
+  });
+
   it('should overwrite top-level settings from workspace (shallow merge)', () => {
     const userSettings = {
       showMemoryUsage: false,

packages/a2a-server/src/config/settings.ts

@@ -48,6 +48,9 @@ export interface Settings {
     enableRecursiveFileSearch?: boolean;
     customIgnoreFilePaths?: string[];
   };
+  experimental?: {
+    enableAgents?: boolean;
+  };
 }
 
 export interface SettingsError {

packages/core/src/agents/a2a-client-manager.test.ts

@@ -66,11 +66,13 @@ describe('A2AClientManager', () => {
   };
 
   const authFetchMock = vi.fn();
+  const mockConfig = {
+    getProxy: vi.fn(),
+  } as unknown as Config;
 
   beforeEach(() => {
     vi.clearAllMocks();
-    A2AClientManager.resetInstanceForTesting();
+    manager = new A2AClientManager(mockConfig);
-    manager = A2AClientManager.getInstance();
 
     // Re-create the instances as plain objects that can be spied on
     const factoryInstance = {
@@ -124,12 +126,6 @@ describe('A2AClientManager', () => {
     vi.unstubAllGlobals();
   });
 
-  it('should enforce the singleton pattern', () => {
-    const instance1 = A2AClientManager.getInstance();
-    const instance2 = A2AClientManager.getInstance();
-    expect(instance1).toBe(instance2);
-  });
-
   describe('getInstance / dispatcher initialization', () => {
     it('should use UndiciAgent when no proxy is configured', async () => {
       await manager.loadAgent('TestAgent', 'http://test.agent/card');
@@ -152,12 +148,11 @@ describe('A2AClientManager', () => {
     });
 
     it('should use ProxyAgent when a proxy is configured via Config', async () => {
-      A2AClientManager.resetInstanceForTesting();
+      const mockConfigWithProxy = {
-      const mockConfig = {
         getProxy: () => 'http://my-proxy:8080',
       } as Config;
 
-      manager = A2AClientManager.getInstance(mockConfig);
+      manager = new A2AClientManager(mockConfigWithProxy);
       await manager.loadAgent('TestProxyAgent', 'http://test.proxy.agent/card');
 
       const resolverOptions = vi.mocked(DefaultAgentCardResolver).mock

packages/core/src/agents/a2a-client-manager.ts

@@ -49,8 +49,6 @@ const A2A_TIMEOUT = 1800000; // 30 minutes
  * Manages protocol negotiation, authentication, and transport selection.
  */
 export class A2AClientManager {
-  private static instance: A2AClientManager;
-
   // Each agent should manage their own context/taskIds/card/etc
   private clients = new Map<string, Client>();
   private agentCards = new Map<string, AgentCard>();
@@ -58,8 +56,8 @@ export class A2AClientManager {
   private a2aDispatcher: UndiciAgent | ProxyAgent;
   private a2aFetch: typeof fetch;
 
-  private constructor(config?: Config) {
+  constructor(private readonly config: Config) {
-    const proxyUrl = config?.getProxy();
+    const proxyUrl = this.config.getProxy();
     const agentOptions = {
       headersTimeout: A2A_TIMEOUT,
       bodyTimeout: A2A_TIMEOUT,
@@ -78,25 +76,6 @@ export class A2AClientManager {
       fetch(input, { ...init, dispatcher: this.a2aDispatcher } as RequestInit);
   }
 
-  /**
-   * Gets the singleton instance of the A2AClientManager.
-   */
-  static getInstance(config?: Config): A2AClientManager {
-    if (!A2AClientManager.instance) {
-      A2AClientManager.instance = new A2AClientManager(config);
-    }
-    return A2AClientManager.instance;
-  }
-
-  /**
-   * Resets the singleton instance. Only for testing purposes.
-   * @internal
-   */
-  static resetInstanceForTesting() {
-    // @ts-expect-error - Resetting singleton for testing
-    A2AClientManager.instance = undefined;
-  }
-
   /**
    * Loads an agent by fetching its AgentCard and caches the client.
    * @param name The name to assign to the agent.

packages/core/src/agents/registry.test.ts

@@ -15,7 +15,7 @@ import type {
 } from '../config/config.js';
 import { debugLogger } from '../utils/debugLogger.js';
 import { coreEvents, CoreEvent } from '../utils/events.js';
-import { A2AClientManager } from './a2a-client-manager.js';
+import type { A2AClientManager } from './a2a-client-manager.js';
 import {
   DEFAULT_GEMINI_FLASH_LITE_MODEL,
   DEFAULT_GEMINI_MODEL,
@@ -40,9 +40,7 @@ vi.mock('./agentLoader.js', () => ({
 }));
 
 vi.mock('./a2a-client-manager.js', () => ({
-  A2AClientManager: {
+  A2AClientManager: vi.fn(),
-    getInstance: vi.fn(),
-  },
 }));
 
 vi.mock('./auth-provider/factory.js', () => ({
@@ -450,7 +448,7 @@ describe('AgentRegistry', () => {
       );
 
       // Mock A2AClientManager to avoid network calls
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockResolvedValue({ name: 'RemoteAgent' }),
         clearCache: vi.fn(),
       } as unknown as A2AClientManager);
@@ -548,7 +546,7 @@ describe('AgentRegistry', () => {
         inputConfig: { inputSchema: { type: 'object' } },
       };
 
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockResolvedValue({ name: 'RemoteAgent' }),
       } as unknown as A2AClientManager);
 
@@ -583,7 +581,7 @@ describe('AgentRegistry', () => {
       const loadAgentSpy = vi
         .fn()
         .mockResolvedValue({ name: 'RemoteAgentWithAuth' });
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: loadAgentSpy,
         clearCache: vi.fn(),
       } as unknown as A2AClientManager);
@@ -622,7 +620,7 @@ describe('AgentRegistry', () => {
 
       vi.mocked(A2AAuthProviderFactory.create).mockResolvedValue(undefined);
       const loadAgentSpy = vi.fn();
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: loadAgentSpy,
         clearCache: vi.fn(),
       } as unknown as A2AClientManager);
@@ -645,6 +643,9 @@ describe('AgentRegistry', () => {
     it('should log remote agent registration in debug mode', async () => {
       const debugConfig = makeMockedConfig({ debugMode: true });
       const debugRegistry = new TestableAgentRegistry(debugConfig);
+      vi.spyOn(debugConfig, 'getA2AClientManager').mockReturnValue({
+        loadAgent: vi.fn().mockResolvedValue({ name: 'RemoteAgent' }),
+      } as unknown as A2AClientManager);
       const debugLogSpy = vi
         .spyOn(debugLogger, 'log')
         .mockImplementation(() => {});
@@ -657,10 +658,6 @@ describe('AgentRegistry', () => {
         inputConfig: { inputSchema: { type: 'object' } },
       };
 
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
-        loadAgent: vi.fn().mockResolvedValue({ name: 'RemoteAgent' }),
-      } as unknown as A2AClientManager);
-
       await debugRegistry.testRegisterAgent(remoteAgent);
 
       expect(debugLogSpy).toHaveBeenCalledWith(
@@ -688,7 +685,7 @@ describe('AgentRegistry', () => {
         new Error('ECONNREFUSED'),
       );
 
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockRejectedValue(a2aError),
       } as unknown as A2AClientManager);
 
@@ -714,7 +711,7 @@ describe('AgentRegistry', () => {
         inputConfig: { inputSchema: { type: 'object' } },
       };
 
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockRejectedValue(new Error('unexpected crash')),
       } as unknown as A2AClientManager);
 
@@ -749,7 +746,7 @@ describe('AgentRegistry', () => {
         // No auth configured
       };
 
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockResolvedValue({
           name: 'SecuredAgent',
           securitySchemes: {
@@ -783,7 +780,7 @@ describe('AgentRegistry', () => {
       };
 
       const error = new Error('401 Unauthorized');
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockRejectedValue(error),
       } as unknown as A2AClientManager);
 
@@ -815,7 +812,7 @@ describe('AgentRegistry', () => {
         ],
       };
 
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockResolvedValue(mockAgentCard),
         clearCache: vi.fn(),
       } as unknown as A2AClientManager);
@@ -843,7 +840,7 @@ describe('AgentRegistry', () => {
         skills: [{ name: 'Skill1', description: 'Desc1' }],
       };
 
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockResolvedValue(mockAgentCard),
         clearCache: vi.fn(),
       } as unknown as A2AClientManager);
@@ -871,7 +868,7 @@ describe('AgentRegistry', () => {
         skills: [],
       };
 
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockResolvedValue(mockAgentCard),
         clearCache: vi.fn(),
       } as unknown as A2AClientManager);
@@ -902,7 +899,7 @@ describe('AgentRegistry', () => {
         skills: [{ name: 'Skill1', description: 'Desc1' }],
       };
 
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockResolvedValue(mockAgentCard),
         clearCache: vi.fn(),
       } as unknown as A2AClientManager);
@@ -930,7 +927,7 @@ describe('AgentRegistry', () => {
         inputConfig: { inputSchema: { type: 'object' } },
       };
 
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockResolvedValue({
           name: 'EmptyDescAgent',
           description: 'Loaded from card',
@@ -955,7 +952,7 @@ describe('AgentRegistry', () => {
         inputConfig: { inputSchema: { type: 'object' } },
       };
 
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockResolvedValue({
           name: 'SkillFallbackAgent',
           description: 'Card description',
@@ -1092,7 +1089,7 @@ describe('AgentRegistry', () => {
         inputConfig: { inputSchema: { type: 'object' } },
       };
 
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockResolvedValue({ name: 'RemotePolicyAgent' }),
       } as unknown as A2AClientManager);
 
@@ -1141,7 +1138,7 @@ describe('AgentRegistry', () => {
         inputConfig: { inputSchema: { type: 'object' } },
       };
 
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(mockConfig, 'getA2AClientManager').mockReturnValue({
         loadAgent: vi.fn().mockResolvedValue({ name: 'OverwrittenAgent' }),
       } as unknown as A2AClientManager);
 
@@ -1189,8 +1186,10 @@ describe('AgentRegistry', () => {
       });
 
       const clearCacheSpy = vi.fn();
-      vi.mocked(A2AClientManager.getInstance).mockReturnValue({
+      vi.spyOn(config, 'getA2AClientManager').mockReturnValue({
         clearCache: clearCacheSpy,
+        loadAgent: vi.fn(),
+        getClient: vi.fn(),
       } as unknown as A2AClientManager);
 
       const emitSpy = vi.spyOn(coreEvents, 'emitAgentsRefreshed');

packages/core/src/agents/registry.ts

@@ -13,7 +13,6 @@ import { CodebaseInvestigatorAgent } from './codebase-investigator.js';
 import { CliHelpAgent } from './cli-help-agent.js';
 import { GeneralistAgent } from './generalist-agent.js';
 import { BrowserAgentDefinition } from './browser/browserAgentDefinition.js';
-import { A2AClientManager } from './a2a-client-manager.js';
 import { A2AAuthProviderFactory } from './auth-provider/factory.js';
 import type { AuthenticationHandler } from '@a2a-js/sdk/client';
 import { type z } from 'zod';
@@ -69,7 +68,7 @@ export class AgentRegistry {
    * Clears the current registry and re-scans for agents.
    */
   async reload(): Promise<void> {
-    A2AClientManager.getInstance(this.config).clearCache();
+    this.config.getA2AClientManager()?.clearCache();
     await this.config.reloadAgents();
     this.agents.clear();
     this.allDefinitions.clear();
@@ -414,7 +413,13 @@ export class AgentRegistry {
 
     // Load the remote A2A agent card and register.
     try {
-      const clientManager = A2AClientManager.getInstance(this.config);
+      const clientManager = this.config.getA2AClientManager();
+      if (!clientManager) {
+        debugLogger.warn(
+          `[AgentRegistry] Skipping remote agent '${definition.name}': A2AClientManager is not available.`,
+        );
+        return;
+      }
       let authHandler: AuthenticationHandler | undefined;
       if (definition.auth) {
         const provider = await A2AAuthProviderFactory.create({

packages/core/src/agents/remote-invocation.test.ts

@@ -13,21 +13,27 @@ import {
   afterEach,
   type Mock,
 } from 'vitest';
+import type { Client } from '@a2a-js/sdk/client';
 import { RemoteAgentInvocation } from './remote-invocation.js';
 import {
-  A2AClientManager,
   type SendMessageResult,
+  type A2AClientManager,
 } from './a2a-client-manager.js';
+
 import type { RemoteAgentDefinition } from './types.js';
 import { createMockMessageBus } from '../test-utils/mock-message-bus.js';
 import { A2AAuthProviderFactory } from './auth-provider/factory.js';
 import type { A2AAuthProvider } from './auth-provider/types.js';
+import type { AgentLoopContext } from '../config/agent-loop-context.js';
+import type { Config } from '../config/config.js';
 
 // Mock A2AClientManager
 vi.mock('./a2a-client-manager.js', () => ({
-  A2AClientManager: {
+  A2AClientManager: vi.fn().mockImplementation(() => ({
-    getInstance: vi.fn(),
+    getClient: vi.fn(),
-  },
+    loadAgent: vi.fn(),
+    sendMessageStream: vi.fn(),
+  })),
 }));
 
 // Mock A2AAuthProviderFactory
@@ -49,16 +55,40 @@ describe('RemoteAgentInvocation', () => {
     },
   };
 
-  const mockClientManager = {
+  let mockClientManager: {
-    getClient: vi.fn(),
+    getClient: Mock<A2AClientManager['getClient']>;
-    loadAgent: vi.fn(),
+    loadAgent: Mock<A2AClientManager['loadAgent']>;
-    sendMessageStream: vi.fn(),
+    sendMessageStream: Mock<A2AClientManager['sendMessageStream']>;
   };
+  let mockContext: AgentLoopContext;
   const mockMessageBus = createMockMessageBus();
 
+  const mockClient = {
+    sendMessageStream: vi.fn(),
+    getTask: vi.fn(),
+    cancelTask: vi.fn(),
+  } as unknown as Client;
+
   beforeEach(() => {
     vi.clearAllMocks();
-    (A2AClientManager.getInstance as Mock).mockReturnValue(mockClientManager);
+
+    mockClientManager = {
+      getClient: vi.fn(),
+      loadAgent: vi.fn(),
+      sendMessageStream: vi.fn(),
+    };
+
+    const mockConfig = {
+      getA2AClientManager: vi.fn().mockReturnValue(mockClientManager),
+      injectionService: {
+        getLatestInjectionIndex: vi.fn().mockReturnValue(0),
+      },
+    } as unknown as Config;
+
+    mockContext = {
+      config: mockConfig,
+    } as unknown as AgentLoopContext;
+
     (
       RemoteAgentInvocation as unknown as {
         sessionState?: Map<string, { contextId?: string; taskId?: string }>;
@@ -75,6 +105,7 @@ describe('RemoteAgentInvocation', () => {
       expect(() => {
         new RemoteAgentInvocation(
           mockDefinition,
+          mockContext,
           { query: 'valid' },
           mockMessageBus,
         );
@@ -83,12 +114,17 @@ describe('RemoteAgentInvocation', () => {
 
     it('accepts missing query (defaults to "Get Started!")', () => {
       expect(() => {
-        new RemoteAgentInvocation(mockDefinition, {}, mockMessageBus);
+        new RemoteAgentInvocation(
+          mockDefinition,
+          mockContext,
+          {},
+          mockMessageBus,
+        );
       }).not.toThrow();
     });
 
     it('uses "Get Started!" default when query is missing during execution', async () => {
-      mockClientManager.getClient.mockReturnValue({});
+      mockClientManager.getClient.mockReturnValue(mockClient);
       mockClientManager.sendMessageStream.mockImplementation(
         async function* () {
           yield {
@@ -102,6 +138,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         {},
         mockMessageBus,
       );
@@ -118,6 +155,7 @@ describe('RemoteAgentInvocation', () => {
       expect(() => {
         new RemoteAgentInvocation(
           mockDefinition,
+          mockContext,
           { query: 123 },
           mockMessageBus,
         );
@@ -141,6 +179,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         {
           query: 'hi',
         },
@@ -187,6 +226,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation = new RemoteAgentInvocation(
         authDefinition,
+        mockContext,
         { query: 'hi' },
         mockMessageBus,
       );
@@ -220,6 +260,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation = new RemoteAgentInvocation(
         authDefinition,
+        mockContext,
         { query: 'hi' },
         mockMessageBus,
       );
@@ -231,7 +272,7 @@ describe('RemoteAgentInvocation', () => {
     });
 
     it('should not load the agent if already present', async () => {
-      mockClientManager.getClient.mockReturnValue({});
+      mockClientManager.getClient.mockReturnValue(mockClient);
       mockClientManager.sendMessageStream.mockImplementation(
         async function* () {
           yield {
@@ -245,6 +286,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         {
           query: 'hi',
         },
@@ -256,7 +298,7 @@ describe('RemoteAgentInvocation', () => {
     });
 
     it('should persist contextId and taskId across invocations', async () => {
-      mockClientManager.getClient.mockReturnValue({});
+      mockClientManager.getClient.mockReturnValue(mockClient);
 
       // First call return values
       mockClientManager.sendMessageStream.mockImplementationOnce(
@@ -274,6 +316,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation1 = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         {
           query: 'first',
         },
@@ -305,6 +348,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation2 = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         {
           query: 'second',
         },
@@ -335,6 +379,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation3 = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         {
           query: 'third',
         },
@@ -356,6 +401,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation4 = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         {
           query: 'fourth',
         },
@@ -371,7 +417,7 @@ describe('RemoteAgentInvocation', () => {
     });
 
     it('should handle streaming updates and reassemble output', async () => {
-      mockClientManager.getClient.mockReturnValue({});
+      mockClientManager.getClient.mockReturnValue(mockClient);
       mockClientManager.sendMessageStream.mockImplementation(
         async function* () {
           yield {
@@ -392,6 +438,7 @@ describe('RemoteAgentInvocation', () => {
       const updateOutput = vi.fn();
       const invocation = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         { query: 'hi' },
         mockMessageBus,
       );
@@ -402,7 +449,7 @@ describe('RemoteAgentInvocation', () => {
     });
 
     it('should abort when signal is aborted during streaming', async () => {
-      mockClientManager.getClient.mockReturnValue({});
+      mockClientManager.getClient.mockReturnValue(mockClient);
       const controller = new AbortController();
       mockClientManager.sendMessageStream.mockImplementation(
         async function* () {
@@ -425,6 +472,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         { query: 'hi' },
         mockMessageBus,
       );
@@ -435,7 +483,7 @@ describe('RemoteAgentInvocation', () => {
     });
 
     it('should handle errors gracefully', async () => {
-      mockClientManager.getClient.mockReturnValue({});
+      mockClientManager.getClient.mockReturnValue(mockClient);
       mockClientManager.sendMessageStream.mockImplementation(
         async function* () {
           if (Math.random() < 0) yield {} as unknown as SendMessageResult;
@@ -445,6 +493,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         {
           query: 'hi',
         },
@@ -458,7 +507,7 @@ describe('RemoteAgentInvocation', () => {
     });
 
     it('should use a2a helpers for extracting text', async () => {
-      mockClientManager.getClient.mockReturnValue({});
+      mockClientManager.getClient.mockReturnValue(mockClient);
       // Mock a complex message part that needs extraction
       mockClientManager.sendMessageStream.mockImplementation(
         async function* () {
@@ -476,6 +525,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         {
           query: 'hi',
         },
@@ -488,7 +538,7 @@ describe('RemoteAgentInvocation', () => {
     });
 
     it('should handle mixed response types during streaming (TaskStatusUpdateEvent + Message)', async () => {
-      mockClientManager.getClient.mockReturnValue({});
+      mockClientManager.getClient.mockReturnValue(mockClient);
       mockClientManager.sendMessageStream.mockImplementation(
         async function* () {
           yield {
@@ -518,6 +568,7 @@ describe('RemoteAgentInvocation', () => {
       const updateOutput = vi.fn();
       const invocation = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         { query: 'hi' },
         mockMessageBus,
       );
@@ -532,17 +583,20 @@ describe('RemoteAgentInvocation', () => {
     });
 
     it('should handle artifact reassembly with append: true', async () => {
-      mockClientManager.getClient.mockReturnValue({});
+      mockClientManager.getClient.mockReturnValue(mockClient);
       mockClientManager.sendMessageStream.mockImplementation(
         async function* () {
           yield {
             kind: 'status-update',
             taskId: 'task-1',
+            contextId: 'ctx-1',
+            final: false,
             status: {
               state: 'working',
               message: {
                 kind: 'message',
                 role: 'agent',
+                messageId: 'm1',
                 parts: [{ kind: 'text', text: 'Generating...' }],
               },
             },
@@ -550,6 +604,7 @@ describe('RemoteAgentInvocation', () => {
           yield {
             kind: 'artifact-update',
             taskId: 'task-1',
+            contextId: 'ctx-1',
             append: false,
             artifact: {
               artifactId: 'art-1',
@@ -560,18 +615,21 @@ describe('RemoteAgentInvocation', () => {
           yield {
             kind: 'artifact-update',
             taskId: 'task-1',
+            contextId: 'ctx-1',
             append: true,
             artifact: {
               artifactId: 'art-1',
               parts: [{ kind: 'text', text: ' Part 2' }],
             },
           };
+          return;
         },
       );
 
       const updateOutput = vi.fn();
       const invocation = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         { query: 'hi' },
         mockMessageBus,
       );
@@ -591,6 +649,7 @@ describe('RemoteAgentInvocation', () => {
     it('should return info confirmation details', async () => {
       const invocation = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         {
           query: 'hi',
         },
@@ -629,6 +688,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         { query: 'hi' },
         mockMessageBus,
       );
@@ -646,6 +706,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         { query: 'hi' },
         mockMessageBus,
       );
@@ -658,7 +719,7 @@ describe('RemoteAgentInvocation', () => {
     });
 
     it('should include partial output when error occurs mid-stream', async () => {
-      mockClientManager.getClient.mockReturnValue({});
+      mockClientManager.getClient.mockReturnValue(mockClient);
       mockClientManager.sendMessageStream.mockImplementation(
         async function* () {
           yield {
@@ -674,6 +735,7 @@ describe('RemoteAgentInvocation', () => {
 
       const invocation = new RemoteAgentInvocation(
         mockDefinition,
+        mockContext,
         { query: 'hi' },
         mockMessageBus,
       );

packages/core/src/agents/remote-invocation.ts

@@ -16,10 +16,11 @@ import {
   type RemoteAgentDefinition,
   type AgentInputs,
 } from './types.js';
+import { type AgentLoopContext } from '../config/agent-loop-context.js';
 import type { MessageBus } from '../confirmation-bus/message-bus.js';
-import {
+import type {
   A2AClientManager,
-  type SendMessageResult,
+  SendMessageResult,
 } from './a2a-client-manager.js';
 import { extractIdsFromResponse, A2AResultReassembler } from './a2aUtils.js';
 import type { AuthenticationHandler } from '@a2a-js/sdk/client';
@@ -47,13 +48,13 @@ export class RemoteAgentInvocation extends BaseToolInvocation<
   // State for the ongoing conversation with the remote agent
   private contextId: string | undefined;
   private taskId: string | undefined;
-  // TODO: See if we can reuse the singleton from AppContainer or similar, but for now use getInstance directly
+
-  // as per the current pattern in the codebase.
+  private readonly clientManager: A2AClientManager;
-  private readonly clientManager = A2AClientManager.getInstance();
   private authHandler: AuthenticationHandler | undefined;
 
   constructor(
     private readonly definition: RemoteAgentDefinition,
+    private readonly context: AgentLoopContext,
     params: AgentInputs,
     messageBus: MessageBus,
     _toolName?: string,
@@ -72,6 +73,13 @@ export class RemoteAgentInvocation extends BaseToolInvocation<
       _toolName ?? definition.name,
       _toolDisplayName ?? definition.displayName,
     );
+    const clientManager = this.context.config.getA2AClientManager();
+    if (!clientManager) {
+      throw new Error(
+        `Failed to initialize RemoteAgentInvocation for '${definition.name}': A2AClientManager is not available.`,
+      );
+    }
+    this.clientManager = clientManager;
   }
 
   getDescription(): string {

packages/core/src/agents/subagent-tool-wrapper.ts

@@ -75,6 +75,7 @@ export class SubagentToolWrapper extends BaseDeclarativeTool<
     if (definition.kind === 'remote') {
       return new RemoteAgentInvocation(
         definition,
+        this.context,
         params,
         effectiveMessageBus,
         _toolName,

packages/core/src/config/config.test.ts

@@ -1523,7 +1523,7 @@ describe('Server Config (config.ts)', () => {
 
       const paramsWithProxy: ConfigParameters = {
         ...baseParams,
-        proxy: 'invalid-proxy',
+        proxy: 'http://invalid-proxy:8080',
       };
       new Config(paramsWithProxy);
 

packages/core/src/config/config.ts

@@ -405,6 +405,7 @@ import {
   SimpleExtensionLoader,
 } from '../utils/extensionLoader.js';
 import { McpClientManager } from '../tools/mcp-client-manager.js';
+import { A2AClientManager } from '../agents/a2a-client-manager.js';
 import { type McpContext } from '../tools/mcp-client.js';
 import type { EnvironmentSanitizationConfig } from '../services/environmentSanitization.js';
 import { getErrorMessage } from '../utils/errors.js';
@@ -653,6 +654,7 @@ export interface ConfigParameters {
 export class Config implements McpContext, AgentLoopContext {
   private _toolRegistry!: ToolRegistry;
   private mcpClientManager?: McpClientManager;
+  private readonly a2aClientManager?: A2AClientManager;
   private allowedMcpServers: string[];
   private blockedMcpServers: string[];
   private allowedEnvironmentVariables: string[];
@@ -1188,6 +1190,7 @@ export class Config implements McpContext, AgentLoopContext {
       params.toolSandboxing ?? false,
       this.targetDir,
     );
+    this.a2aClientManager = new A2AClientManager(this);
     this.shellExecutionConfig.sandboxManager = this._sandboxManager;
     this.modelRouterService = new ModelRouterService(this);
   }
@@ -2000,6 +2003,10 @@ export class Config implements McpContext, AgentLoopContext {
     return this.mcpClientManager;
   }
 
+  getA2AClientManager(): A2AClientManager | undefined {
+    return this.a2aClientManager;
+  }
+
   setUserInteractedWithMcp(): void {
     this.mcpClientManager?.setUserInteractedWithMcp();
   }

packages/core/src/policy/policy-engine.test.ts

@@ -15,6 +15,7 @@ import {
   ApprovalMode,
   PRIORITY_SUBAGENT_TOOL,
   ALWAYS_ALLOW_PRIORITY_FRACTION,
+  PRIORITY_YOLO_ALLOW_ALL,
 } from './types.js';
 import type { FunctionCall } from '@google/genai';
 import { SafetyCheckDecision } from '../safety/protocol.js';
@@ -2852,7 +2853,7 @@ describe('PolicyEngine', () => {
         },
         {
           decision: PolicyDecision.ALLOW,
-          priority: 998,
+          priority: PRIORITY_YOLO_ALLOW_ALL,
           modes: [ApprovalMode.YOLO],
         },
       ];
@@ -2879,7 +2880,7 @@ describe('PolicyEngine', () => {
         },
         {
           decision: PolicyDecision.ALLOW,
-          priority: 998,
+          priority: PRIORITY_YOLO_ALLOW_ALL,
           modes: [ApprovalMode.YOLO],
         },
       ];

packages/core/src/policy/types.ts

@@ -345,3 +345,9 @@ export const ALWAYS_ALLOW_PRIORITY_FRACTION = 950;
  */
 export const ALWAYS_ALLOW_PRIORITY_OFFSET =
   ALWAYS_ALLOW_PRIORITY_FRACTION / 1000;
+
+/**
+ * Priority for the YOLO "allow all" rule.
+ * Matches the raw priority used in yolo.toml.
+ */
+export const PRIORITY_YOLO_ALLOW_ALL = 998;