Don't accumulate historical references in Ask mode (#245929)

* Don't accumulate historical references in Ask mode
For microsoft/vscode-copilot-release#7290

Author: roblourens

src/vs/workbench/contrib/chat/browser/chatWidget.ts

@@ -1109,7 +1109,7 @@ export class ChatWidget extends Disposable implements IChatWidget {
 			}
 
 			let attachedContext = this.inputPart.getAttachedAndImplicitContext(this.viewModel.sessionId);
-			if (this.viewOptions.enableWorkingSet !== undefined) {
+			if (this.viewOptions.enableWorkingSet !== undefined && this.input.currentMode !== ChatMode.Ask) {
 				const uniqueWorkingSetEntries = new ResourceSet(); // NOTE: this is used for bookkeeping so the UI can avoid rendering references in the UI that are already shown in the working set
 				const editingSessionAttachedContext: IChatRequestVariableEntry[] = attachedContext;