fix(a2a): Don't mutate 'replace' tool args in scheduleToolCalls (#7369)

Co-authored-by: Abhi <43648792+abhipatel12@users.noreply.github.com>

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

@@ -33,6 +33,7 @@ import {
   assertTaskCreationAndWorkingStatus,
   createStreamMessageRequest,
   MockTool,
+  createMockConfig,
 } from './testing_utils.js';
 
 const mockToolConfirmationFn = async () =>
@@ -68,26 +69,11 @@ vi.mock('./config.js', async () => {
   return {
     ...actual,
     loadConfig: vi.fn().mockImplementation(async () => {
-      config = {
+      const mockConfig = createMockConfig({
         getToolRegistry: getToolRegistrySpy,
         getApprovalMode: getApprovalModeSpy,
-        getIdeMode: vi.fn().mockReturnValue(false),
-        getAllowedTools: vi.fn().mockReturnValue([]),
-        getIdeClient: vi.fn(),
-        getWorkspaceContext: vi.fn().mockReturnValue({
-          isPathWithinWorkspace: () => true,
-        }),
-        getTargetDir: () => '/test',
-        getGeminiClient: vi.fn(),
-        getDebugMode: vi.fn().mockReturnValue(false),
-        getContentGeneratorConfig: vi
-          .fn()
-          .mockReturnValue({ model: 'gemini-pro' }),
-        getModel: vi.fn().mockReturnValue('gemini-pro'),
-        getUsageStatisticsEnabled: vi.fn().mockReturnValue(false),
-        setFlashFallbackHandler: vi.fn(),
-        initialize: vi.fn().mockResolvedValue(undefined),
-      } as unknown as Config;
+      });
+      config = mockConfig as Config;
       return config;
     }),
   };

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

@@ -0,0 +1,59 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, vi } from 'vitest';
+import { Task } from './task.js';
+import type { Config, ToolCallRequestInfo } from '@google/gemini-cli-core';
+import { createMockConfig } from './testing_utils.js';
+import type { ExecutionEventBus } from '@a2a-js/sdk/server';
+
+describe('Task', () => {
+  it('scheduleToolCalls should not modify the input requests array', async () => {
+    const mockConfig = createMockConfig();
+
+    const mockEventBus: ExecutionEventBus = {
+      publish: vi.fn(),
+      on: vi.fn(),
+      off: vi.fn(),
+      once: vi.fn(),
+      removeAllListeners: vi.fn(),
+      finished: vi.fn(),
+    };
+
+    // The Task constructor is private. We'll bypass it for this unit test.
+    // @ts-expect-error - Calling private constructor for test purposes.
+    const task = new Task(
+      'task-id',
+      'context-id',
+      mockConfig as Config,
+      mockEventBus,
+    );
+
+    task['setTaskStateAndPublishUpdate'] = vi.fn();
+    task['getProposedContent'] = vi.fn().mockResolvedValue('new content');
+
+    const requests: ToolCallRequestInfo[] = [
+      {
+        callId: '1',
+        name: 'replace',
+        args: {
+          file_path: 'test.txt',
+          old_string: 'old',
+          new_string: 'new',
+        },
+        isClientInitiated: false,
+        prompt_id: 'prompt-id-1',
+      },
+    ];
+
+    const originalRequests = JSON.parse(JSON.stringify(requests));
+    const abortController = new AbortController();
+
+    await task.scheduleToolCalls(requests, abortController.signal);
+
+    expect(requests).toEqual(originalRequests);
+  });
+});

packages/a2a-server/src/task.ts

@@ -520,30 +520,36 @@ export class Task {
       return;
     }
 
-    for (const request of requests) {
-      if (
-        !request.args['newContent'] &&
-        request.name === 'replace' &&
-        request.args &&
-        request.args['file_path'] &&
-        request.args['old_string'] &&
-        request.args['new_string']
-      ) {
-        request.args['newContent'] = await this.getProposedContent(
-          request.args['file_path'] as string,
-          request.args['old_string'] as string,
-          request.args['new_string'] as string,
-        );
-      }
-    }
+    const updatedRequests = await Promise.all(
+      requests.map(async (request) => {
+        if (
+          request.name === 'replace' &&
+          request.args &&
+          !request.args['newContent'] &&
+          request.args['file_path'] &&
+          request.args['old_string'] &&
+          request.args['new_string']
+        ) {
+          const newContent = await this.getProposedContent(
+            request.args['file_path'] as string,
+            request.args['old_string'] as string,
+            request.args['new_string'] as string,
+          );
+          return { ...request, args: { ...request.args, newContent } };
+        }
+        return request;
+      }),
+    );
 
-    logger.info(`[Task] Scheduling batch of ${requests.length} tool calls.`);
+    logger.info(
+      `[Task] Scheduling batch of ${updatedRequests.length} tool calls.`,
+    );
     const stateChange: StateChange = {
       kind: CoderAgentEvent.StateChangeEvent,
     };
     this.setTaskStateAndPublishUpdate('working', stateChange);
 
-    await this.scheduler.schedule(requests, abortSignal);
+    await this.scheduler.schedule(updatedRequests, abortSignal);
   }
 
   async acceptAgentMessage(event: ServerGeminiStreamEvent): Promise<void> {

packages/a2a-server/src/testing_utils.ts

@@ -9,18 +9,52 @@ import type {
   TaskStatusUpdateEvent,
   SendStreamingMessageSuccessResponse,
 } from '@a2a-js/sdk';
+import { ApprovalMode } from '@google/gemini-cli-core';
 import {
   BaseDeclarativeTool,
   BaseToolInvocation,
   Kind,
 } from '@google/gemini-cli-core';
 import type {
+  Config,
   ToolCallConfirmationDetails,
   ToolResult,
   ToolInvocation,
 } from '@google/gemini-cli-core';
 import { expect, vi } from 'vitest';
 
+export function createMockConfig(
+  overrides: Partial<Config> = {},
+): Partial<Config> {
+  const mockConfig = {
+    getToolRegistry: vi.fn().mockReturnValue({
+      getTool: vi.fn(),
+      getAllToolNames: vi.fn().mockReturnValue([]),
+    }),
+    getApprovalMode: vi.fn().mockReturnValue(ApprovalMode.DEFAULT),
+    getIdeMode: vi.fn().mockReturnValue(false),
+    getAllowedTools: vi.fn().mockReturnValue([]),
+    getIdeClient: vi.fn(),
+    getWorkspaceContext: vi.fn().mockReturnValue({
+      isPathWithinWorkspace: () => true,
+    }),
+    getTargetDir: () => '/test',
+    getGeminiClient: vi.fn(),
+    getDebugMode: vi.fn().mockReturnValue(false),
+    getContentGeneratorConfig: vi.fn().mockReturnValue({ model: 'gemini-pro' }),
+    getModel: vi.fn().mockReturnValue('gemini-pro'),
+    getUsageStatisticsEnabled: vi.fn().mockReturnValue(false),
+    setFlashFallbackHandler: vi.fn(),
+    initialize: vi.fn().mockResolvedValue(undefined),
+    getProxy: vi.fn().mockReturnValue(undefined),
+    getHistory: vi.fn().mockReturnValue([]),
+    getEmbeddingModel: vi.fn().mockReturnValue('text-embedding-004'),
+    getSessionId: vi.fn().mockReturnValue('test-session-id'),
+    ...overrides,
+  };
+  return mockConfig;
+}
+
 export const mockOnUserConfirmForToolConfirmation = vi.fn();
 
 export class MockToolInvocation extends BaseToolInvocation<object, ToolResult> {