test: add Object.create context regression test and tool confirmation integration test

integration-tests/browser-agent.confirmation.responses

@@ -0,0 +1 @@
+{"method":"generateContentStream","response":[{"candidates":[{"content":{"parts":[{"functionCall":{"name":"write_file","args":{"file_path":"test.txt","content":"hello"}}},{"text":"I've successfully written \"hello\" to test.txt. The file has been created with the specified content."}],"role":"model"},"finishReason":"STOP","index":0}],"usageMetadata":{"promptTokenCount":100,"candidatesTokenCount":50,"totalTokenCount":150}}]}

integration-tests/browser-agent.test.ts

@@ -203,4 +203,33 @@ describe.skipIf(!chromeAvailable)('browser-agent', () => {
     // Should successfully complete all operations
     assertModelHasOutput(result);
   });
+
+  it('should handle tool confirmation for write_file without crashing', async () => {
+    rig.setup('tool-confirmation', {
+      fakeResponsesPath: join(
+        __dirname,
+        'browser-agent.confirmation.responses',
+      ),
+      settings: {
+        agents: {
+          browser_agent: {
+            headless: true,
+            sessionMode: 'isolated',
+          },
+        },
+      },
+    });
+
+    const run = await rig.runInteractive({ approvalMode: 'default' });
+
+    await run.type('Write hello to test.txt');
+    await run.type('\r');
+
+    await run.expectText('Allow', 15000);
+
+    await run.type('y');
+    await run.type('\r');
+
+    await run.expectText('successfully written', 15000);
+  });
 });

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

@@ -10,7 +10,7 @@ import {
   type ToolInvocation,
   type ToolResult,
 } from '../tools/tools.js';
-import type { Config } from '../config/config.js';
+
 import { type AgentLoopContext } from '../config/agent-loop-context.js';
 import type { AgentDefinition, AgentInputs } from './types.js';
 import { LocalSubagentInvocation } from './local-invocation.js';
@@ -54,10 +54,6 @@ export class SubagentToolWrapper extends BaseDeclarativeTool<
     );
   }
 
-  private get config(): Config {
-    return this.context.config;
-  }
-
   /**
    * Creates an invocation instance for executing the subagent.
    *
@@ -89,7 +85,7 @@ export class SubagentToolWrapper extends BaseDeclarativeTool<
     // Special handling for browser agent - needs async MCP setup
     if (definition.name === BROWSER_AGENT_NAME) {
       return new BrowserAgentInvocation(
-        this.config,
+        this.context,
         params,
         effectiveMessageBus,
         _toolName,

packages/core/src/scheduler/policy.test.ts

@@ -676,6 +676,43 @@ describe('policy.ts', () => {
         }),
       );
     });
+
+    it('should work when context is created via Object.create (prototype chain)', async () => {
+      const mockConfig = {
+        setApprovalMode: vi.fn(),
+      } as unknown as Mocked<Config>;
+      const mockMessageBus = {
+        publish: vi.fn(),
+      } as unknown as Mocked<MessageBus>;
+
+      const baseContext = {
+        config: mockConfig,
+        messageBus: mockMessageBus,
+      };
+      const protoContext: AgentLoopContext = Object.create(baseContext);
+
+      expect(Object.keys(protoContext)).toHaveLength(0);
+      expect(protoContext.config).toBe(mockConfig);
+      expect(protoContext.messageBus).toBe(mockMessageBus);
+
+      const tool = { name: 'test-tool' } as AnyDeclarativeTool;
+
+      await updatePolicy(
+        tool,
+        ToolConfirmationOutcome.ProceedAlways,
+        undefined,
+        protoContext,
+        mockMessageBus,
+      );
+
+      expect(mockMessageBus.publish).toHaveBeenCalledWith(
+        expect.objectContaining({
+          type: MessageBusType.UPDATE_POLICY,
+          toolName: 'test-tool',
+          persist: false,
+        }),
+      );
+    });
   });
 
   describe('getPolicyDenialError', () => {