Handle empty string auto approve case

Fixes microsoft#258719

Author: Tyriar

src/vs/workbench/contrib/terminalContrib/chatAgentTools/browser/commandLineAutoApprover.ts

@@ -17,6 +17,8 @@ interface IAutoApproveRule {
 
 export type ICommandApprovalResult = 'approved' | 'denied' | 'noMatch';
 
+const neverMatchRegex = /(?!.*)/;
+
 export class CommandLineAutoApprover extends Disposable {
 	private _denyListRules: IAutoApproveRule[] = [];
 	private _allowListRules: IAutoApproveRule[] = [];
@@ -177,27 +179,29 @@ export class CommandLineAutoApprover extends Disposable {
 		const regexPattern = regexMatch?.groups?.pattern;
 		if (regexPattern) {
 			let flags = regexMatch.groups?.flags;
-			// Remove global flag as it can cause confusion
+			// Remove global flag as it changes how the regex state works which we need to handle
+			// internally
 			if (flags) {
 				flags = flags.replaceAll('g', '');
 			}
 
 			try {
 				const regex = new RegExp(regexPattern, flags || undefined);
-
-				// Check if the regex would lead to an endless loop
 				if (regExpLeadsToEndlessLoop(regex)) {
-					// Return a regex that will never match anything to prevent endless loops
-					return /(?!.*)/;
+					return neverMatchRegex;
 				}
 
 				return regex;
 			} catch (error) {
-				// If the regex is invalid, return a regex that will never match anything
-				return /(?!.*)/;
+				return neverMatchRegex;
 			}
 		}
 
+		// The empty string should be ignored, rather than approve everything
+		if (value === '') {
+			return neverMatchRegex;
+		}
+
 		// Escape regex special characters
 		const sanitizedValue = value.replace(/[\\^$.*+?()[\]{}|]/g, '\\$&');
 

src/vs/workbench/contrib/terminalContrib/chatAgentTools/test/browser/commandLineAutoApprover.test.ts

@@ -301,11 +301,19 @@ suite('CommandLineAutoApprover', () => {
 			ok(isAutoApproved('pwsh.exe -File D:\\foo.bar\\a-script.ps1 -AnotherArg'));
 		});
 
+		test('should ignore the empty string key', () => {
+			setAutoApprove({
+				"": true
+			});
+
+			ok(!isAutoApproved('echo hello'));
+		});
+
 		test('should handle empty regex patterns that could cause endless loops', () => {
 			setAutoApprove({
 				"//": true,
 				"/(?:)/": true,
-				"/*/": true,            // Invalid regex pattern  
+				"/*/": true,            // Invalid regex pattern
 				"/.**/": true           // Invalid regex pattern
 			});
 
@@ -549,7 +557,7 @@ suite('CommandLineAutoApprover', () => {
 		test('should handle invalid regex patterns with matchCommandLine gracefully', () => {
 			setAutoApproveWithCommandLine({
 				"/*/": { approve: true, matchCommandLine: true },                    // Invalid regex - nothing to repeat
-				"/(?:+/": { approve: true, matchCommandLine: true },                 // Invalid regex - incomplete quantifier  
+				"/(?:+/": { approve: true, matchCommandLine: true },                 // Invalid regex - incomplete quantifier
 				"/[/": { approve: true, matchCommandLine: true },                    // Invalid regex - unclosed character class
 				"/^echo/": { approve: true, matchCommandLine: true },                // Valid pattern
 				"ls": { approve: true, matchCommandLine: true }                      // Valid string pattern