feat(tools): add file read/write/edit/list builtin tools

src/tools/builtin/file-edit.ts

@@ -0,0 +1,48 @@
+import { readFileSync, writeFileSync } from 'fs';
+import type { Tool, ToolResult } from '../types.js';
+
+interface FileEditArgs {
+  path: string;
+  old_string: string;
+  new_string: string;
+  replace_all?: boolean;
+}
+
+export const fileEditTool: Tool = {
+  name: 'file.edit',
+  description: 'Edit a file by replacing an exact string match. Fails if old_string is not found or matches multiple times (unless replace_all is true).',
+  inputSchema: {
+    type: 'object',
+    properties: {
+      path: { type: 'string', description: 'Absolute path to the file' },
+      old_string: { type: 'string', description: 'Exact string to find' },
+      new_string: { type: 'string', description: 'Replacement string' },
+      replace_all: { type: 'boolean', description: 'Replace all occurrences (default false)' },
+    },
+    required: ['path', 'old_string', 'new_string'],
+  },
+  execute: async (rawArgs: unknown): Promise<ToolResult> => {
+    const args = rawArgs as FileEditArgs;
+    try {
+      const content = readFileSync(args.path, 'utf-8');
+
+      if (!content.includes(args.old_string)) {
+        return { success: false, output: '', error: `old_string not found in ${args.path}` };
+      }
+
+      const count = content.split(args.old_string).length - 1;
+      if (count > 1 && !args.replace_all) {
+        return { success: false, output: '', error: `old_string found multiple times (${count}). Use replace_all or provide more context.` };
+      }
+
+      const newContent = args.replace_all
+        ? content.replaceAll(args.old_string, args.new_string)
+        : content.replace(args.old_string, args.new_string);
+
+      writeFileSync(args.path, newContent, 'utf-8');
+      return { success: true, output: `Edited ${args.path} (${count} replacement${count > 1 ? 's' : ''})` };
+    } catch (error) {
+      return { success: false, output: '', error: error instanceof Error ? error.message : String(error) };
+    }
+  },
+};