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/delete_file.test.ts

@@ -0,0 +1,173 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+
+// Mock fs/promises
+vi.mock('fs/promises', () => ({
+  stat: vi.fn(),
+  unlink: vi.fn().mockResolvedValue(undefined),
+  rmdir: vi.fn().mockResolvedValue(undefined),
+  rm: vi.fn().mockResolvedValue(undefined),
+  readdir: vi.fn().mockResolvedValue([]),
+}));
+
+// 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(() => '删除文件'),
+}));
+
+import { deleteFileTool } from '../../../../src/tools/filesystem/delete_file.js';
+import * as fs from 'fs/promises';
+import { getPermissionManager } from '../../../../src/permission/index.js';
+
+describe('deleteFileTool - 文件删除工具', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  describe('工具定义', () => {
+    it('有正确的名称', () => {
+      expect(deleteFileTool.name).toBe('delete_file');
+    });
+
+    it('有正确的元数据', () => {
+      expect(deleteFileTool.metadata.category).toBe('filesystem');
+      expect(deleteFileTool.metadata.keywords).toContain('delete');
+      expect(deleteFileTool.metadata.keywords).toContain('remove');
+      expect(deleteFileTool.metadata.keywords).toContain('rm');
+    });
+
+    it('定义了必需的 path 参数', () => {
+      expect(deleteFileTool.parameters.path.required).toBe(true);
+    });
+
+    it('定义了可选的 recursive 参数', () => {
+      expect(deleteFileTool.parameters.recursive.required).toBe(false);
+    });
+  });
+
+  describe('execute - 执行', () => {
+    it('成功删除文件', async () => {
+      vi.mocked(fs.stat).mockResolvedValue({
+        isDirectory: () => false,
+      } as any);
+
+      const result = await deleteFileTool.execute({ path: 'file.txt' });
+
+      expect(result.success).toBe(true);
+      expect(result.output).toContain('已删除文件');
+      expect(fs.unlink).toHaveBeenCalled();
+    });
+
+    it('删除空目录', async () => {
+      vi.mocked(fs.stat).mockResolvedValue({
+        isDirectory: () => true,
+      } as any);
+      vi.mocked(fs.readdir).mockResolvedValue([]);
+
+      const result = await deleteFileTool.execute({ path: 'empty_dir' });
+
+      expect(result.success).toBe(true);
+      expect(result.output).toContain('已删除目录');
+      expect(fs.rmdir).toHaveBeenCalled();
+    });
+
+    it('非空目录无 recursive 返回错误', async () => {
+      vi.mocked(fs.stat).mockResolvedValue({
+        isDirectory: () => true,
+      } as any);
+      vi.mocked(fs.readdir).mockResolvedValue(['file1.txt', 'file2.txt'] as any);
+
+      const result = await deleteFileTool.execute({ path: 'nonempty_dir' });
+
+      expect(result.success).toBe(false);
+      expect(result.error).toContain('目录不为空');
+      expect(result.error).toContain('recursive: true');
+    });
+
+    it('递归删除非空目录', async () => {
+      vi.mocked(fs.stat).mockResolvedValue({
+        isDirectory: () => true,
+      } as any);
+
+      const result = await deleteFileTool.execute({
+        path: 'nonempty_dir',
+        recursive: true,
+      });
+
+      expect(result.success).toBe(true);
+      expect(result.output).toContain('已删除目录');
+      expect(fs.rm).toHaveBeenCalledWith(
+        expect.any(String),
+        { recursive: 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: '不允许删除',
+        }),
+      } as any);
+
+      const result = await deleteFileTool.execute({ path: '/protected/file' });
+
+      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,
+        }),
+      } as any);
+
+      const result = await deleteFileTool.execute({ path: 'important.txt' });
+
+      expect(result.success).toBe(false);
+      expect(result.error).toContain('需要用户确认');
+    });
+
+    it('文件不存在返回错误', async () => {
+      vi.mocked(getPermissionManager).mockReturnValue({
+        checkFilePermission: vi.fn().mockResolvedValue({ allowed: true }),
+      } as any);
+
+      vi.mocked(fs.stat).mockRejectedValue(new Error('ENOENT'));
+
+      const result = await deleteFileTool.execute({ path: 'nonexistent.txt' });
+
+      expect(result.success).toBe(false);
+      expect(result.error).toContain('ENOENT');
+    });
+
+    it('传递正确参数给权限检查', async () => {
+      const mockCheck = vi.fn().mockResolvedValue({ allowed: true });
+      vi.mocked(getPermissionManager).mockReturnValue({
+        checkFilePermission: mockCheck,
+      } as any);
+      vi.mocked(fs.stat).mockResolvedValue({ isDirectory: () => false } as any);
+
+      await deleteFileTool.execute({ path: 'test.txt' });
+
+      expect(mockCheck).toHaveBeenCalledWith(
+        expect.objectContaining({
+          operation: 'delete',
+        })
+      );
+    });
+  });
+});