diff --git a/changelog.md b/changelog.md
index 6c735e6..31994c0 100644
--- a/changelog.md
+++ b/changelog.md
@@ -18,11 +18,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
     - `autoit.maps.includeDepth` - Maximum depth for resolving #include files (default: 3, range: 0-10)
     - `autoit.maps.showFunctionKeys` - Show Map keys assigned in functions (default: true)
   - See [docs/map-support.md](docs/map-support.md) for performance tuning recommendations
+- Ignore AutoIt Tidy backup files from diagnostics
 
 ### Changed
 
 - Enhanced README documentation with Map intelligence feature details
 
+### Refactored
+
+- Extract and enhance formatter constants into constants.js file
+
 ## [1.3.0] - 2025-11-10
 
 ### Added
diff --git a/src/ai_completion.js b/src/ai_completion.js
index 0d41bd4..24f2865 100644
--- a/src/ai_completion.js
+++ b/src/ai_completion.js
@@ -10,7 +10,7 @@ import {
   setRegExpFlags,
   variablePattern,
 } from './util';
-import DEFAULT_UDFS from './constants';
+import { DEFAULT_UDFS } from './constants';
 import MapTrackingService from './services/MapTrackingService.js';
 
 // Per-document cache for include completions
diff --git a/src/ai_formatter.js b/src/ai_formatter.js
index 186a7ae..0f58880 100644
--- a/src/ai_formatter.js
+++ b/src/ai_formatter.js
@@ -4,15 +4,7 @@ import fs from 'fs/promises';
 import fsSync from 'fs';
 import path from 'path';
 import conf from './ai_config';
-
-// Constants for configuration and file operations
-const FORMATTER_CONSTANTS = {
-  TEMP_FILE_PREFIX: 'temp_format_',
-  BACKUP_DIR_NAME: 'Backup',
-  BACKUP_SUFFIX: '_old1.au3',
-  TIDY_TIMEOUT_MS: 10000, // Increased timeout for better reliability
-  FILE_EXTENSION: '.au3',
-};
+import { FORMATTER } from './constants';
 
 /**
  * AutoIt document formatter provider that integrates with AutoIt3Wrapper Tidy
@@ -45,7 +37,7 @@ const AutoItFormatterProvider = {
     }
 
     const tempFile = generateTempFilePath(workspaceFolder);
-    const backupDir = path.join(workspaceFolder, FORMATTER_CONSTANTS.BACKUP_DIR_NAME);
+    const backupDir = path.join(workspaceFolder, FORMATTER.BACKUP_DIR_NAME);
 
     console.log(`[AutoIt Formatter] Workspace: ${workspaceFolder}`);
     console.log(`[AutoIt Formatter] Temp file: ${tempFile}`);
@@ -157,9 +149,9 @@ async function runTidy(filePath) {
       if (!hasExited && !tidyProcess.killed) {
         hasExited = true;
         tidyProcess.kill('SIGTERM'); // Use SIGTERM for graceful shutdown
-        reject(new Error(`Tidy process timed out after ${FORMATTER_CONSTANTS.TIDY_TIMEOUT_MS}ms`));
+        reject(new Error(`Tidy process timed out after ${FORMATTER.TIDY_TIMEOUT_MS}ms`));
       }
-    }, FORMATTER_CONSTANTS.TIDY_TIMEOUT_MS);
+    }, FORMATTER.TIDY_TIMEOUT_MS);
 
     // Capture stdout and stderr
     tidyProcess.stdout.on('data', data => {
@@ -221,7 +213,7 @@ async function runTidy(filePath) {
 function generateTempFilePath(workspaceFolder) {
   const timestamp = Date.now();
   const randomSuffix = Math.random().toString(36).substring(2, 8);
-  const fileName = `${FORMATTER_CONSTANTS.TEMP_FILE_PREFIX}${timestamp}_${randomSuffix}${FORMATTER_CONSTANTS.FILE_EXTENSION}`;
+  const fileName = `${FORMATTER.TEMP_FILE_PREFIX}${timestamp}_${randomSuffix}${FORMATTER.FILE_EXTENSION}`;
   return path.join(workspaceFolder, fileName);
 }
 
@@ -258,7 +250,7 @@ async function cleanupFiles(tempFile, backupDir) {
   // Clean up backup file if it exists
   const backupFile = path.join(
     backupDir,
-    path.basename(tempFile, FORMATTER_CONSTANTS.FILE_EXTENSION) + FORMATTER_CONSTANTS.BACKUP_SUFFIX,
+    path.basename(tempFile, FORMATTER.FILE_EXTENSION) + FORMATTER.BACKUP_FILE_SUFFIX,
   );
   cleanupPromises.push(
     safeDeleteFile(backupFile).catch(error =>
diff --git a/src/ai_signature.js b/src/ai_signature.js
index fe9f83b..134a153 100644
--- a/src/ai_signature.js
+++ b/src/ai_signature.js
@@ -16,7 +16,7 @@ import {
   libraryIncludePattern,
 } from './util';
 import defaultSigs from './signatures';
-import DEFAULT_UDFS from './constants';
+import { DEFAULT_UDFS } from './constants';
 
 let currentIncludeFiles = [];
 let includes = {};
diff --git a/src/constants.js b/src/constants.js
index 5ab15c5..5509745 100644
--- a/src/constants.js
+++ b/src/constants.js
@@ -140,4 +140,16 @@ const DEFAULT_UDFS = [
   'WordConstants',
 ];
 
-export default DEFAULT_UDFS;
+/**
+ * Formatter constants for AutoIt Tidy and backup operations
+ */
+const FORMATTER = {
+  TEMP_FILE_PREFIX: 'temp_format_',
+  BACKUP_DIR_NAME: 'BackUp',
+  BACKUP_FILE_SUFFIX: '_old1.au3',
+  BACKUP_FILE_SUFFIX_PATTERN: /_old\d*\.au3$/i,
+  TIDY_TIMEOUT_MS: 10000, // Increased timeout for better reliability
+  FILE_EXTENSION: '.au3',
+};
+
+export { DEFAULT_UDFS, FORMATTER };
diff --git a/src/extension.js b/src/extension.js
index efba3c3..4e2967b 100644
--- a/src/extension.js
+++ b/src/extension.js
@@ -1,7 +1,8 @@
 import { languages, window, workspace } from 'vscode';
-import { dirname } from 'path';
+import { basename, dirname, sep } from 'path';
 import { existsSync } from 'fs';
 import { execFile } from 'child_process';
+import { FORMATTER } from './constants';
 import languageConfiguration from './languageConfiguration';
 import hoverFeature from './ai_hover';
 import completionFeature from './ai_completion';
@@ -131,6 +132,28 @@ const validateFormatterPaths = () => {
   return true;
 };
 
+/**
+ * Checks if a document should be ignored by diagnostics (AutoIt Tidy backup files)
+ * @param {import('vscode').TextDocument} document - Document to check
+ * @returns {boolean} True if document should be ignored
+ */
+const shouldIgnoreDiagnostics = document => {
+  const filePath = document.uri.fsPath;
+  const fileName = basename(filePath);
+
+  // Ignore files in "BackUp" folder
+  if (filePath.includes(sep + FORMATTER.BACKUP_DIR_NAME + sep)) {
+    return true;
+  }
+
+  // Ignore *_old*.au3 files
+  if (FORMATTER.BACKUP_FILE_SUFFIX_PATTERN.test(fileName)) {
+    return true;
+  }
+
+  return false;
+};
+
 /**
  * Checks the AutoIt code in the given document and updates the diagnostic collection.
  * @param {import('vscode').TextDocument} document - The document to check.
@@ -144,6 +167,12 @@ const checkAutoItCode = async (document, diagnosticCollection) => {
 
   if (document.languageId !== 'autoit') return;
 
+  // Ignore backup files from AutoIt Tidy
+  if (shouldIgnoreDiagnostics(document)) {
+    diagnosticCollection.delete(document.uri);
+    return;
+  }
+
   const { checkPath } = config;
   if (!validateCheckPath(checkPath)) return;