feat(core): 优化 read_file 工具参数结构

- 将参数 path 重命名为 file_path
- 添加 offset 参数支持从指定行开始读取
- 添加 limit 参数控制读取行数（默认 2000 行）
- 输出带行号格式（类似 cat -n）
- 大文件时显示剩余行数提示

packages/core/src/tools/filesystem/read_file.ts

@@ -5,6 +5,8 @@ import type { ToolWithMetadata } from '../types.js';
 import { loadDescription } from '../load_description.js';
 import { getPermissionManager } from '../../permission/index.js';
 
+const DEFAULT_LINE_LIMIT = 2000;
+
 export const readFileTool: ToolWithMetadata = {
   name: 'read_file',
   description: loadDescription('read_file'),
@@ -16,14 +18,26 @@ export const readFileTool: ToolWithMetadata = {
     deferLoading: false, // 核心工具，始终可用
   },
   parameters: {
-    path: {
+    file_path: {
       type: 'string',
-      description: '要读取的文件路径（相对或绝对路径）',
+      description: 'The absolute path to the file to read',
       required: true,
     },
+    offset: {
+      type: 'number',
+      description: 'The line number to start reading from. Only provide if the file is too large to read at once',
+      required: false,
+    },
+    limit: {
+      type: 'number',
+      description: 'The number of lines to read. Only provide if the file is too large to read at once.',
+      required: false,
+    },
   },
   execute: async (params: Record<string, unknown>): Promise<ToolResult> => {
-    const filePath = params.path as string;
+    const filePath = params.file_path as string;
+    const offset = (params.offset as number | undefined) ?? 0;
+    const limit = (params.limit as number | undefined) ?? DEFAULT_LINE_LIMIT;
     const cwd = process.cwd();
     const absolutePath = path.isAbsolute(filePath)
       ? filePath
@@ -54,9 +68,40 @@ export const readFileTool: ToolWithMetadata = {
 
     try {
       const content = await fs.readFile(absolutePath, 'utf-8');
+      const lines = content.split('\n');
+      const totalLines = lines.length;
+
+      // 应用 offset 和 limit
+      const startLine = Math.max(0, offset);
+      const endLine = Math.min(totalLines, startLine + limit);
+      const selectedLines = lines.slice(startLine, endLine);
+
+      // 格式化输出（带行号，类似 cat -n）
+      const formattedOutput = selectedLines
+        .map((line, index) => {
+          const lineNumber = startLine + index + 1;
+          return `${String(lineNumber).padStart(6, ' ')}\t${line}`;
+        })
+        .join('\n');
+
+      // 构建元数据
+      const metadata: Record<string, unknown> = {
+        totalLines,
+        startLine: startLine + 1,
+        endLine,
+        linesRead: selectedLines.length,
+      };
+
+      // 如果有更多内容未显示，添加提示
+      let output = formattedOutput;
+      if (endLine < totalLines) {
+        output += `\n\n--- 文件共 ${totalLines} 行，当前显示 ${startLine + 1}-${endLine} 行，还有 ${totalLines - endLine} 行未显示 ---`;
+      }
+
       return {
         success: true,
-        output: content,
+        output,
+        metadata,
       };
     } catch (error) {
       return {