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/tools/filesystem/read_file.test.ts

@@ -0,0 +1,142 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { readFileTool } from '../../../../src/tools/filesystem/read_file.js';
+
+// Mock fs/promises
+vi.mock('fs/promises', () => ({
+  readFile: vi.fn(),
+}));
+
+// Mock permission manager
+vi.mock('../../../../src/permission/index.js', () => ({
+  getPermissionManager: vi.fn(() => ({
+    checkFilePermission: vi.fn().mockResolvedValue({
+      allowed: true,
+      action: 'allow',
+    }),
+  })),
+}));
+
+// Mock loadDescription
+vi.mock('../../../../src/tools/load_description.js', () => ({
+  loadDescription: vi.fn(() => '读取文件内容'),
+}));
+
+import * as fs from 'fs/promises';
+import { getPermissionManager } from '../../../../src/permission/index.js';
+
+describe('readFileTool - 读取文件工具', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  describe('工具定义', () => {
+    it('有正确的名称', () => {
+      expect(readFileTool.name).toBe('read_file');
+    });
+
+    it('有正确的元数据', () => {
+      expect(readFileTool.metadata.category).toBe('filesystem');
+      expect(readFileTool.metadata.keywords).toContain('read');
+      expect(readFileTool.metadata.keywords).toContain('file');
+    });
+
+    it('定义了必需的 path 参数', () => {
+      expect(readFileTool.parameters.path).toBeDefined();
+      expect(readFileTool.parameters.path.required).toBe(true);
+      expect(readFileTool.parameters.path.type).toBe('string');
+    });
+  });
+
+  describe('execute - 执行', () => {
+    it('成功读取文件', async () => {
+      const mockContent = 'Hello, World!';
+      vi.mocked(fs.readFile).mockResolvedValue(mockContent);
+
+      const result = await readFileTool.execute({ path: './test.txt' });
+
+      expect(result.success).toBe(true);
+      expect(result.output).toBe(mockContent);
+    });
+
+    it('处理绝对路径', async () => {
+      vi.mocked(fs.readFile).mockResolvedValue('content');
+
+      await readFileTool.execute({ path: '/absolute/path/file.txt' });
+
+      expect(fs.readFile).toHaveBeenCalledWith('/absolute/path/file.txt', 'utf-8');
+    });
+
+    it('处理相对路径', async () => {
+      vi.mocked(fs.readFile).mockResolvedValue('content');
+
+      await readFileTool.execute({ path: './relative/file.txt' });
+
+      // 应该解析为绝对路径
+      expect(fs.readFile).toHaveBeenCalled();
+      const calledPath = vi.mocked(fs.readFile).mock.calls[0][0] as string;
+      expect(calledPath.endsWith('relative/file.txt')).toBe(true);
+    });
+
+    it('权限被拒绝时返回错误', async () => {
+      vi.mocked(getPermissionManager).mockReturnValue({
+        checkFilePermission: vi.fn().mockResolvedValue({
+          allowed: false,
+          action: 'deny',
+          reason: '不允许读取此文件',
+        }),
+      } as any);
+
+      const result = await readFileTool.execute({ path: '/etc/passwd' });
+
+      expect(result.success).toBe(false);
+      expect(result.error).toContain('权限被拒绝');
+    });
+
+    it('需要确认时返回提示', async () => {
+      vi.mocked(getPermissionManager).mockReturnValue({
+        checkFilePermission: vi.fn().mockResolvedValue({
+          allowed: false,
+          action: 'ask',
+          needsConfirmation: true,
+          reason: '需要确认',
+        }),
+      } as any);
+
+      const result = await readFileTool.execute({ path: './sensitive.txt' });
+
+      expect(result.success).toBe(false);
+      expect(result.error).toContain('需要用户确认');
+    });
+
+    it('文件不存在时返回错误', async () => {
+      vi.mocked(getPermissionManager).mockReturnValue({
+        checkFilePermission: vi.fn().mockResolvedValue({
+          allowed: true,
+          action: 'allow',
+        }),
+      } as any);
+      vi.mocked(fs.readFile).mockRejectedValue(new Error('ENOENT: no such file'));
+
+      const result = await readFileTool.execute({ path: './nonexistent.txt' });
+
+      expect(result.success).toBe(false);
+      expect(result.error).toContain('ENOENT');
+    });
+
+    it('读取大文件', async () => {
+      const largeContent = 'x'.repeat(10000);
+      vi.mocked(getPermissionManager).mockReturnValue({
+        checkFilePermission: vi.fn().mockResolvedValue({
+          allowed: true,
+          action: 'allow',
+        }),
+      } as any);
+      vi.mocked(fs.readFile).mockResolvedValue(largeContent);
+
+      const result = await readFileTool.execute({ path: './large.txt' });
+
+      expect(result.success).toBe(true);
+      expect(result.output.length).toBe(10000);
+    });
+  });
+});