feat: 添加后台 Agent 执行和模型选择功能

- 新增 AgentManager 管理后台 Agent 生命周期
- Task 工具支持 run_in_background 参数实现后台执行
- Task 工具支持 model 参数选择 sonnet/opus/haiku 模型
- 新增 agent_output 工具查询后台 Agent 执行状态和结果
- 添加 AgentManager 和 AgentOutput 工具单元测试

tests/unit/tools/task/agent_output.test.ts

@@ -0,0 +1,160 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { agentOutputTool } from '../../../../src/tools/task/agent_output.js';
+import { getAgentManager, resetAgentManager } from '../../../../src/agent/manager.js';
+
+// Mock AgentExecutor - 使用延迟执行让测试更可控
+vi.mock('../../../../src/agent/executor.js', () => ({
+  AgentExecutor: vi.fn().mockImplementation(() => ({
+    execute: vi.fn().mockImplementation(async () => {
+      await new Promise((r) => setTimeout(r, 50));
+      return {
+        success: true,
+        text: '任务完成结果',
+        steps: 3,
+        sessionId: 'test-session',
+      };
+    }),
+  })),
+}));
+
+describe('agentOutputTool - Agent 输出工具', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    resetAgentManager();
+  });
+
+  describe('工具定义', () => {
+    it('有正确的名称', () => {
+      expect(agentOutputTool.name).toBe('agent_output');
+    });
+
+    it('有正确的元数据', () => {
+      expect(agentOutputTool.metadata.category).toBe('agent');
+      expect(agentOutputTool.metadata.keywords).toContain('agent');
+      expect(agentOutputTool.metadata.keywords).toContain('output');
+      expect(agentOutputTool.metadata.keywords).toContain('background');
+    });
+
+    it('agent_id 参数是必须的', () => {
+      expect(agentOutputTool.parameters.agent_id.required).toBe(true);
+    });
+
+    it('block 和 timeout 参数是可选的', () => {
+      expect(agentOutputTool.parameters.block.required).toBe(false);
+      expect(agentOutputTool.parameters.timeout.required).toBe(false);
+    });
+  });
+
+  describe('execute - 执行', () => {
+    it('Agent 不存在时返回错误', async () => {
+      const result = await agentOutputTool.execute({
+        agent_id: 'non-existent-id',
+      });
+
+      expect(result.success).toBe(false);
+      expect(result.error).toContain('不存在');
+    });
+
+    it('返回 Agent 的状态', async () => {
+      const manager = getAgentManager();
+      const agentId = await manager.runInBackground(
+        {
+          name: 'test-agent',
+          description: '测试',
+          mode: 'subagent',
+        },
+        '测试任务',
+        '执行测试',
+        {
+          provider: 'anthropic',
+          apiKey: 'test',
+          model: 'test',
+          maxTokens: 1000,
+          systemPrompt: 'test',
+        },
+        {} as any,
+        { parentSessionId: 'parent', workdir: '/test' }
+      );
+
+      // 立即查询（不阻塞）
+      const result = await agentOutputTool.execute({
+        agent_id: agentId,
+        block: false,
+      });
+
+      // 应该成功返回状态（可能是 running 或 completed）
+      expect(result.output).toBeDefined();
+      expect(result.metadata?.agentId).toBe(agentId);
+    });
+
+    it('阻塞等待后返回结果', async () => {
+      const manager = getAgentManager();
+      const agentId = await manager.runInBackground(
+        {
+          name: 'test-agent',
+          description: '测试',
+          mode: 'subagent',
+        },
+        '测试任务',
+        '执行测试',
+        {
+          provider: 'anthropic',
+          apiKey: 'test',
+          model: 'test',
+          maxTokens: 1000,
+          systemPrompt: 'test',
+        },
+        {} as any,
+        { parentSessionId: 'parent', workdir: '/test' }
+      );
+
+      // 使用阻塞模式等待
+      const result = await agentOutputTool.execute({
+        agent_id: agentId,
+        block: true,
+        timeout: 5,
+      });
+
+      // 等待后应该有确定的状态
+      expect(result.metadata?.status).toBeDefined();
+      expect(['running', 'completed', 'failed']).toContain(result.metadata?.status);
+    });
+
+    it('返回包含正确字段的输出', async () => {
+      const manager = getAgentManager();
+      const agentId = await manager.runInBackground(
+        {
+          name: 'test-agent',
+          description: '测试',
+          mode: 'subagent',
+        },
+        '测试任务',
+        '执行测试',
+        {
+          provider: 'anthropic',
+          apiKey: 'test',
+          model: 'test',
+          maxTokens: 1000,
+          systemPrompt: 'test',
+        },
+        {} as any,
+        { parentSessionId: 'parent', workdir: '/test' }
+      );
+
+      // 等待完成
+      await new Promise((r) => setTimeout(r, 200));
+
+      const result = await agentOutputTool.execute({
+        agent_id: agentId,
+        block: false,
+      });
+
+      // 检查返回了有效结果
+      expect(result.output).toBeDefined();
+      expect(result.metadata?.agentId).toBe(agentId);
+      expect(result.metadata?.agentName).toBe('test-agent');
+      // 状态应该是完成或失败（由于 mock，可能会失败）
+      expect(['completed', 'failed']).toContain(result.metadata?.status);
+    });
+  });
+});