Enhance chat todo list widget scroll handling and state management (microsoft#262845)

Author: bhavyaus

src/vs/workbench/contrib/chat/browser/chatContentParts/chatTodoListWidget.ts

@@ -24,6 +24,7 @@ export class ChatTodoListWidget extends Disposable {
 	private clearButtonContainer!: HTMLElement;
 	private clearButton!: Button;
 	private _currentSessionId: string | undefined;
+	private _userHasScrolledManually: boolean = false;
 
 	constructor(
 		@IChatTodoListService private readonly chatTodoListService: IChatTodoListService
@@ -84,6 +85,7 @@ export class ChatTodoListWidget extends Disposable {
 
 		this._register(dom.addDisposableListener(this.todoListContainer, 'scroll', () => {
 			this.updateScrollShadow();
+			this._userHasScrolledManually = true;
 		}));
 
 		return container;
@@ -110,6 +112,11 @@ export class ChatTodoListWidget extends Disposable {
 			return;
 		}
 
+		if (this._currentSessionId !== sessionId) {
+			this._userHasScrolledManually = false;
+			this._userManuallyExpanded = false;
+		}
+
 		const todoList = this.chatTodoListService.getTodos(sessionId);
 		if (todoList.length > 0) {
 			this.renderTodoList(todoList);
@@ -162,6 +169,12 @@ export class ChatTodoListWidget extends Disposable {
 			this.updateTitleElement(titleElement, todoList);
 		}
 
+		const allIncomplete = todoList.every(todo => todo.status === 'not-started');
+		if (allIncomplete) {
+			this._userHasScrolledManually = false;
+			this._userManuallyExpanded = false;
+		}
+
 		let lastActiveIndex = -1;
 		let firstCompletedIndex = -1;
 		let firstPendingAfterCompletedIndex = -1;
@@ -259,7 +272,7 @@ export class ChatTodoListWidget extends Disposable {
 	}
 
 	private scrollToRelevantItem(lastActiveIndex: number, firstCompletedIndex: number, firstPendingAfterCompletedIndex: number, totalItems: number): void {
-		if (totalItems <= 6) {
+		if (totalItems <= 6 || this._userHasScrolledManually) {
 			return;
 		}