feat(file-highlight): add fileHighlightReadRange function to highlight read ranges in client editor

Author: AndyLiner13

src/client-pipe.ts

@@ -810,6 +810,24 @@ export async function fileReadContent(
   return result;
 }
 
+/**
+ * Open a file in the client editor and highlight the range that was just read.
+ * Fire-and-forget — does not block the tool response.
+ */
+export function fileHighlightReadRange(
+  filePath: string,
+  startLine: number,
+  endLine: number,
+): void {
+  sendClientRequest(
+    'file.highlightReadRange',
+    {filePath, startLine, endLine},
+    5_000,
+  ).catch(() => {
+    // Best-effort — don't let highlight failures affect tool responses
+  });
+}
+
 /**
  * Apply a text replacement (range → new content) and save.
  */

src/extension-watcher.ts

@@ -26,7 +26,7 @@ import path, {extname, join, relative} from 'node:path';
 
 import {logger} from './logger.js';
 
-const IGNORE_DIRS = new Set(['node_modules', 'dist', '.git']);
+const IGNORE_DIRS = new Set(['node_modules', 'dist', '.git', '.devtools']);
 const IGNORE_EXTENSIONS = new Set(['.vsix']);
 const DEVTOOLS_IGNORE_FILENAME = '.devtoolsignore';
 const EXT_FINGERPRINT_DIR = '.devtools';

src/tools/file/file-read.ts

@@ -6,7 +6,7 @@
 
 import path from 'node:path';
 
-import {fileGetSymbols, fileReadContent} from '../../client-pipe.js';
+import {fileGetSymbols, fileReadContent, fileHighlightReadRange} from '../../client-pipe.js';
 import {getHostWorkspace} from '../../config.js';
 import {zod} from '../../third_party/index.js';
 import {ToolCategory} from '../categories.js';
@@ -108,6 +108,9 @@ export const read = defineTool({
 
     const contentResult = await fileReadContent(filePath, readStartLine, readEndLine);
 
+    // Fire-and-forget: highlight the read range in the client editor
+    fileHighlightReadRange(filePath, contentResult.startLine, contentResult.endLine);
+
     // Truncate if necessary
     let content = contentResult.content;
     let truncated = false;