feat: 添加完整的单元测试套件

- 新增 vitest 测试框架配置
- 添加 54 个测试文件，共 951 个测试用例
- 覆盖核心模块：
  - Agent: executor, registry, config-loader, permission-merger
  - Context: manager, compaction, prune, token-counter
  - Permission: manager, bash/file/git/web checkers, wildcard
  - Session: manager, storage
  - Tools: filesystem (12个), git (10个), web, shell, todo, task
  - LSP: client, server, language
  - Utils: config, diff
  - UI: terminal

tests/unit/utils/config.test.ts

@@ -0,0 +1,195 @@
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
+
+// Mock fs
+vi.mock('fs', () => ({
+  existsSync: vi.fn(),
+  readFileSync: vi.fn(),
+  writeFileSync: vi.fn(),
+  mkdirSync: vi.fn(),
+}));
+
+import * as fs from 'fs';
+import { getConfig, loadConfig, saveConfig } from '../../../src/utils/config.js';
+
+describe('Config - 配置管理', () => {
+  const originalEnv = { ...process.env };
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    // 清理环境变量
+    delete process.env.AI_PROVIDER;
+    delete process.env.ANTHROPIC_API_KEY;
+    delete process.env.DEEPSEEK_API_KEY;
+    delete process.env.AI_MODEL;
+    delete process.env.AI_MAX_TOKENS;
+  });
+
+  afterEach(() => {
+    // 恢复环境变量
+    process.env = { ...originalEnv };
+  });
+
+  describe('getConfig - 获取原始配置', () => {
+    it('配置文件存在时返回内容', () => {
+      vi.mocked(fs.existsSync).mockReturnValue(true);
+      vi.mocked(fs.readFileSync).mockReturnValue(JSON.stringify({
+        provider: 'anthropic',
+        apiKey: 'test-key',
+        model: 'claude-3-opus',
+      }));
+
+      const config = getConfig();
+
+      expect(config.provider).toBe('anthropic');
+      expect(config.apiKey).toBe('test-key');
+      expect(config.model).toBe('claude-3-opus');
+    });
+
+    it('配置文件不存在时返回空对象', () => {
+      vi.mocked(fs.existsSync).mockReturnValue(false);
+
+      const config = getConfig();
+
+      expect(config).toEqual({});
+    });
+
+    it('配置文件解析错误时返回空对象', () => {
+      vi.mocked(fs.existsSync).mockReturnValue(true);
+      vi.mocked(fs.readFileSync).mockReturnValue('invalid json');
+
+      const config = getConfig();
+
+      expect(config).toEqual({});
+    });
+  });
+
+  describe('loadConfig - 加载完整配置', () => {
+    it('从环境变量获取 Anthropic 配置', () => {
+      process.env.ANTHROPIC_API_KEY = 'env-anthropic-key';
+      vi.mocked(fs.existsSync).mockReturnValue(false);
+
+      const config = loadConfig();
+
+      expect(config.provider).toBe('anthropic');
+      expect(config.apiKey).toBe('env-anthropic-key');
+      expect(config.model).toBe('claude-sonnet-4-20250514');
+    });
+
+    it('从环境变量获取 DeepSeek 配置', () => {
+      process.env.AI_PROVIDER = 'deepseek';
+      process.env.DEEPSEEK_API_KEY = 'env-deepseek-key';
+      vi.mocked(fs.existsSync).mockReturnValue(false);
+
+      const config = loadConfig();
+
+      expect(config.provider).toBe('deepseek');
+      expect(config.apiKey).toBe('env-deepseek-key');
+      expect(config.model).toBe('deepseek-chat');
+    });
+
+    it('配置文件优先级高于默认值', () => {
+      process.env.ANTHROPIC_API_KEY = 'env-key';
+      vi.mocked(fs.existsSync).mockReturnValue(true);
+      vi.mocked(fs.readFileSync).mockReturnValue(JSON.stringify({
+        model: 'custom-model',
+        maxTokens: 8192,
+      }));
+
+      const config = loadConfig();
+
+      expect(config.model).toBe('custom-model');
+      expect(config.maxTokens).toBe(8192);
+    });
+
+    it('配置文件中的 provider 优先', () => {
+      process.env.ANTHROPIC_API_KEY = 'anthropic-key';
+      process.env.DEEPSEEK_API_KEY = 'deepseek-key';
+      vi.mocked(fs.existsSync).mockReturnValue(true);
+      vi.mocked(fs.readFileSync).mockReturnValue(JSON.stringify({
+        provider: 'deepseek',
+        deepseekApiKey: 'stored-deepseek-key',
+      }));
+
+      const config = loadConfig();
+
+      expect(config.provider).toBe('deepseek');
+      // 使用环境变量中的 API Key（优先级更高）
+      expect(config.apiKey).toBe('deepseek-key');
+    });
+
+    it('包含系统提示词', () => {
+      process.env.ANTHROPIC_API_KEY = 'test-key';
+      vi.mocked(fs.existsSync).mockReturnValue(false);
+
+      const config = loadConfig();
+
+      expect(config.systemPrompt).toBeDefined();
+      expect(config.systemPrompt).toContain('终端');
+    });
+
+    it('默认 maxTokens 为 4096', () => {
+      process.env.ANTHROPIC_API_KEY = 'test-key';
+      vi.mocked(fs.existsSync).mockReturnValue(false);
+
+      const config = loadConfig();
+
+      expect(config.maxTokens).toBe(4096);
+    });
+
+    it('环境变量设置的 maxTokens', () => {
+      process.env.ANTHROPIC_API_KEY = 'test-key';
+      process.env.AI_MAX_TOKENS = '16384';
+      vi.mocked(fs.existsSync).mockReturnValue(false);
+
+      const config = loadConfig();
+
+      expect(config.maxTokens).toBe(16384);
+    });
+  });
+
+  describe('saveConfig - 保存配置', () => {
+    it('创建目录并保存配置', () => {
+      vi.mocked(fs.existsSync).mockReturnValue(false);
+
+      saveConfig({ provider: 'anthropic', apiKey: 'new-key' });
+
+      expect(fs.mkdirSync).toHaveBeenCalledWith(
+        expect.any(String),
+        { recursive: true }
+      );
+      expect(fs.writeFileSync).toHaveBeenCalledWith(
+        expect.any(String),
+        expect.stringContaining('anthropic')
+      );
+    });
+
+    it('合并现有配置', () => {
+      vi.mocked(fs.existsSync).mockReturnValue(true);
+      vi.mocked(fs.readFileSync).mockReturnValue(JSON.stringify({
+        provider: 'anthropic',
+        apiKey: 'old-key',
+        model: 'old-model',
+      }));
+
+      saveConfig({ apiKey: 'new-key' });
+
+      const writeCall = vi.mocked(fs.writeFileSync).mock.calls[0];
+      const savedConfig = JSON.parse(writeCall[1] as string);
+
+      expect(savedConfig.provider).toBe('anthropic'); // 保留
+      expect(savedConfig.apiKey).toBe('new-key'); // 更新
+      expect(savedConfig.model).toBe('old-model'); // 保留
+    });
+
+    it('目录已存在时不重新创建', () => {
+      vi.mocked(fs.existsSync)
+        .mockReturnValueOnce(true)  // 目录存在
+        .mockReturnValueOnce(true); // 配置文件存在
+      vi.mocked(fs.readFileSync).mockReturnValue('{}');
+
+      saveConfig({ apiKey: 'test' });
+
+      expect(fs.mkdirSync).not.toHaveBeenCalled();
+    });
+  });
+});