feat: 升级至 v0.3.3 — 新增 delete_file 工具 + 文件工具全面优化

## 主要变更

### 1. 新增 delete_file 工具（26 → 27 个）
- 支持：删除文件/空目录（默认）/递归删除非空目录（recursive: true）
- 5 层安全防护：
  * isPathWithinWorkspace — 路径遍历防护
  * isProtectedWorkspaceFile — MEMORY.md 拦截
  * 工作空间根目录保护 — 禁止删除 workspace 本身
  * 递归删除需显式开启 — 默认仅删空目录
  * riskLevel: HIGH + requiresPermission — 破坏性操作必须确认
- 友好错误处理：ENOTEMPTY 时提示设置 recursive: true

### 2. 文件工具全面优化（6 个工具）
- 抽取共享代码到 file-guard.ts：
  * safeResolvePath — 合并路径遍历 + MEMORY.md 校验
  * matchGlob — 简易通配符匹配
  * extractErrorMessage — 统一错误提取
  * MAX_FILE_SIZE_BYTES (10MB) / FILE_TOOL_TIMEOUT_MS (15s) / MAX_LINE_LENGTH (10000)
- read_file：stat 预检 + 超长行截断 + 二进制检测 + 大小上限
- write_file：原子写入（临时文件+rename）+ 内容大小上限 + append 返回 new_file_size
- list_directory：1000 结果上限 + modified time + include_hidden 参数 + 提前终止优化
- search_files：regex lastIndex 修复 + context_lines + include_hidden + 大文件跳过
- file_editor：dry_run 预览模式 + 文件大小上限

### 3. 审计修复（1 FAIL + 3 WARN）
- FAIL: isBinaryFile 用 bytesRead 限制循环，修复 < 8KB 文本误判为二进制
- WARN-1: file-editor dry_run preview 分模式计算，修复 insert 范围过大
- WARN-2: write_file 允许空字符串创建空文件
- WARN-3: list_directory listDir 提前终止，避免大目录全量遍历

electron/harness/tools/built-in/file-editor.ts

@@ -6,34 +6,34 @@
  * 相比 write_file 的整文件覆盖，file_editor 支持精准定位修改，
  * 避免大文件全量重写，减少 token 消耗和出错风险。
  *
+ * v0.3.2 优化：
+ * - 使用共享 safeResolvePath（消除重复代码）
+ * - 使用共享 extractErrorMessage、FILE_TOOL_TIMEOUT_MS、MAX_FILE_SIZE_BYTES
+ * - 新增 dry_run 模式（预览变更不写入）
+ * - 文件大小上限（防止 OOM）
+ * - 统一 timeoutMs 为 15_000
+ *
  * @see docs/MetonaAI-Desktop 架构与交互设计.html — 9 个基础工具
  */
 
-import { readFile, writeFile, rename, mkdir } from 'fs/promises';
+import { readFile, writeFile, rename, mkdir, stat, unlink } from 'fs/promises';
 import { dirname } from 'path';
 import { existsSync } from 'fs';
 import type { IMetonaTool, ToolExecutionContext } from '../../types/metona-tool';
 import type { MetonaToolDef } from '../../../harness/types';
 import { MetonaToolCategory, MetonaRiskLevel } from '../../../harness/types';
-import { isProtectedWorkspaceFile, isPathWithinWorkspace } from './file-guard';
-import { resolve } from 'path';
-
-/** 安全校验：路径遍历防护 + 受保护文件拦截 */
-function safeResolvePath(filePath: string, workspacePath: string): string {
-  const resolved = resolve(workspacePath, filePath);
-  if (!isPathWithinWorkspace(filePath, workspacePath)) {
-    throw new Error(`Path traversal detected: ${filePath}`);
-  }
-  if (isProtectedWorkspaceFile(filePath, workspacePath)) {
-    throw new Error('Access denied: MEMORY.md is managed by the memory system and cannot be accessed via file tools');
-  }
-  return resolved;
-}
+import {
+  safeResolvePath,
+  extractErrorMessage,
+  MAX_FILE_SIZE_BYTES,
+  FILE_TOOL_TIMEOUT_MS,
+} from './file-guard';
 
 export class FileEditorTool implements IMetonaTool {
   readonly definition: MetonaToolDef = {
     name: 'file_editor',
-    description: 'Edit a file with precision. Supports operations: replace (replace lines), insert (insert at line), delete (delete lines), regex (regex replace in range). More efficient than write_file for targeted edits.',
+    description:
+      'Edit a file with precision. Supports operations: replace (replace lines), insert (insert at line), delete (delete lines), regex (regex replace in range). More efficient than write_file for targeted edits. Supports dry_run mode for preview. File size limit: 10MB.',
     parameters: {
       type: 'object',
       properties: {
@@ -49,13 +49,14 @@ export class FileEditorTool implements IMetonaTool {
         pattern: { type: 'string', description: 'Regex pattern for regex operation' },
         replacement: { type: 'string', description: 'Replacement string for regex operation' },
         flags: { type: 'string', description: 'Regex flags (default "g")' },
+        dry_run: { type: 'boolean', description: 'Preview mode: return the diff without writing to file (default false)' },
       },
       required: ['file_path', 'operation'],
     },
     category: MetonaToolCategory.FILESYSTEM,
     riskLevel: MetonaRiskLevel.MEDIUM,
     requiresPermission: true,
-    timeoutMs: 15_000,
+    timeoutMs: FILE_TOOL_TIMEOUT_MS,
   };
 
   async execute(args: Record<string, unknown>, context: ToolExecutionContext): Promise<unknown> {
@@ -66,17 +67,28 @@ export class FileEditorTool implements IMetonaTool {
       }
       const filePath = safeResolvePath(args.file_path as string, context.workspacePath);
       const operation = args.operation as 'replace' | 'insert' | 'delete' | 'regex';
+      const dryRun = (args.dry_run as boolean) ?? false;
 
       // 文件必须存在（不支持创建新文件，请用 write_file）
       if (!existsSync(filePath)) {
         return { success: false, error: `File not found: ${args.file_path}. Use write_file to create new files.` };
       }
 
+      // v0.3.2: 文件大小上限（防止 OOM）
+      const stats = await stat(filePath);
+      if (stats.size > MAX_FILE_SIZE_BYTES) {
+        return {
+          success: false,
+          error: `File too large (${stats.size} bytes, max ${MAX_FILE_SIZE_BYTES} bytes). Consider using write_file to rewrite.`,
+        };
+      }
+
       const originalContent = await readFile(filePath, 'utf-8');
       const lines = originalContent.split('\n');
 
       let newLines: string[];
       let affectedRange: { start: number; end: number };
+      let replaceCount = 0;  // v0.3.2: 统一在外层声明，供 dry_run 返回
 
       switch (operation) {
         case 'replace': {
@@ -93,6 +105,7 @@ export class FileEditorTool implements IMetonaTool {
             ...lines.slice(endLine),
           ];
           affectedRange = { start: startLine, end: endLine };
+          replaceCount = endLine - startLine + 1;
           break;
         }
 
@@ -107,6 +120,7 @@ export class FileEditorTool implements IMetonaTool {
             ...lines.slice(startLine - 1),
           ];
           affectedRange = { start: startLine, end: startLine + contentLines.length - 1 };
+          replaceCount = contentLines.length;
           break;
         }
 
@@ -121,6 +135,7 @@ export class FileEditorTool implements IMetonaTool {
             ...lines.slice(endLine),
           ];
           affectedRange = { start: startLine, end: endLine };
+          replaceCount = endLine - startLine + 1;
           break;
         }
 
@@ -149,7 +164,6 @@ export class FileEditorTool implements IMetonaTool {
           }
 
           // F1.4: 用带 g 标志的正则统计匹配数
-          let replaceCount = 0;
           const targetLines = lines.slice(startLine - 1, endLine);
           const countRegex = new RegExp(pattern, flags.includes('g') ? flags : flags + 'g');
           const replacedLines = targetLines.map((line) => {
@@ -174,6 +188,7 @@ export class FileEditorTool implements IMetonaTool {
               message: 'No matches found for regex pattern',
               replacements: 0,
               affected_range: affectedRange,
+              dry_run: dryRun,
             };
           }
 
@@ -184,6 +199,55 @@ export class FileEditorTool implements IMetonaTool {
           return { success: false, error: `Unknown operation: ${operation}` };
       }
 
+      // v0.3.2: dry_run 模式 — 预览变更不写入
+      if (dryRun) {
+        // v0.3.2 修复 WARN-1: 分模式计算 preview 范围
+        // - insert: affectedRange.end 是新文件行号，原文件无被替换内容 → original 为空
+        // - replace/delete/regex: affectedRange.end 是原文件行号，original/modified 取相同范围
+        let originalPreview: string;
+        let modifiedPreview: string;
+
+        if (operation === 'insert') {
+          // insert: 原文件无被替换内容；新文件显示插入的内容
+          originalPreview = '';
+          modifiedPreview = newLines.slice(
+            affectedRange.start - 1,
+            Math.min(affectedRange.end, newLines.length),
+          ).join('\n');
+        } else {
+          // replace/delete/regex: 原文件取 [start-1, end) 区间
+          originalPreview = lines.slice(
+            affectedRange.start - 1,
+            Math.min(affectedRange.end, lines.length),
+          ).join('\n');
+          // 新文件取相同范围 + 行数差修正（replace 可能改变行数，delete 后该位置为空）
+          const lineDelta = newLines.length - lines.length;
+          const modifiedEnd = Math.min(
+            affectedRange.end + lineDelta,
+            newLines.length,
+          );
+          modifiedPreview = newLines.slice(
+            affectedRange.start - 1,
+            Math.max(affectedRange.start - 1, modifiedEnd),
+          ).join('\n');
+        }
+
+        return {
+          success: true,
+          dry_run: true,
+          operation,
+          file_path: args.file_path,
+          affected_range: affectedRange,
+          replacements: replaceCount,
+          lines_before: lines.length,
+          lines_after: newLines.length,
+          preview: {
+            original: originalPreview,
+            modified: modifiedPreview,
+          },
+        };
+      }
+
       // 自动创建父目录 (F1.8: 异步 mkdir)
       const parentDir = dirname(filePath);
       if (!existsSync(parentDir)) {
@@ -193,20 +257,29 @@ export class FileEditorTool implements IMetonaTool {
       const newContent = newLines.join('\n');
       // F1.7: 原子写入 - 临时文件 + rename
       const tmpPath = `${filePath}.tmp_${Date.now()}`;
-      await writeFile(tmpPath, newContent, 'utf-8');
-      await rename(tmpPath, filePath);
+      try {
+        await writeFile(tmpPath, newContent, 'utf-8');
+        await rename(tmpPath, filePath);
+      } catch (err) {
+        // 原子写入失败，清理临时文件
+        if (existsSync(tmpPath)) {
+          try { await unlink(tmpPath); } catch { /* 忽略清理错误 */ }
+        }
+        throw err;
+      }
 
       return {
         success: true,
         operation,
         file_path: args.file_path,
         affected_range: affectedRange,
+        replacements: replaceCount,
         lines_before: lines.length,
         lines_after: newLines.length,
         bytes_written: Buffer.byteLength(newContent, 'utf-8'),
       };
     } catch (err) {
-      return { success: false, error: (err as Error).message };
+      return { success: false, error: extractErrorMessage(err) };
     }
   }
 }