Fix progressive rendering issues (#179432)

- Tried to do progressive rendering while the view is hidden, this led to calling updateElementHeight with a height of 0 which apparently caused the list to not want to rerender that element later, so now we stop rendering when the view is not visible
- Not restarting progressive rendering when revealing the view again
- Restarting progressive rendering unnecessarily after completing it due to trying to cancel the timer before starting it

src/vs/workbench/contrib/interactiveSession/browser/interactiveSessionListRenderer.ts

@@ -97,6 +97,7 @@ export class InteractiveListItemRenderer extends Disposable implements ITreeRend
 	private readonly _editorPool: EditorPool;
 
 	private _currentLayoutWidth: number = 0;
+	private _isVisible = true;
 
 	constructor(
 		private readonly editorOptions: InteractiveSessionEditorOptions,
@@ -150,6 +151,10 @@ export class InteractiveListItemRenderer extends Disposable implements ITreeRend
 		return 8;
 	}
 
+	setVisible(visible: boolean): void {
+		this._isVisible = visible;
+	}
+
 	layout(width: number): void {
 		this._currentLayoutWidth = width - 40; // TODO Padding
 		this._editorPool.inUse.forEach(editor => {
@@ -239,8 +244,8 @@ export class InteractiveListItemRenderer extends Disposable implements ITreeRend
 					throw err;
 				}
 			};
-			runProgressiveRender(true);
 			timer.cancelAndSet(runProgressiveRender, 50);
+			runProgressiveRender(true);
 		} else if (isResponseVM(element)) {
 			this.basicRenderElement(element.response.value, element, index, templateData);
 		} else if (isRequestVM(element)) {
@@ -306,7 +311,14 @@ export class InteractiveListItemRenderer extends Disposable implements ITreeRend
 		}
 	}
 
+	/**
+	 *	@returns true if progressive rendering should be considered complete- the element's data is fully rendered or the view is not visible
+	 */
 	private doNextProgressiveRender(element: IInteractiveResponseViewModel, index: number, templateData: IInteractiveListItemTemplate, isInRenderElement: boolean, disposables: DisposableStore): boolean {
+		if (!this._isVisible) {
+			return true;
+		}
+
 		disposables.clear();
 
 		let isFullyRendered = false;

src/vs/workbench/contrib/interactiveSession/browser/interactiveSessionWidget.ts

@@ -74,6 +74,7 @@ export class InteractiveSessionWidget extends Disposable implements IInteractive
 
 	private bodyDimension: dom.Dimension | undefined;
 	private visible = false;
+	private visibleChangeCount = 0;
 	private requestInProgress: IContextKey<boolean>;
 
 	private previousTreeScrollHeight: number = 0;
@@ -184,7 +185,12 @@ export class InteractiveSessionWidget extends Disposable implements IInteractive
 			this.tree.setChildren(null, treeItems, {
 				diffIdentityProvider: {
 					getId: (element) => {
-						return element.id + `${(isRequestVM(element) || isWelcomeVM(element)) && !!this.lastSlashCommands ? '_scLoaded' : ''}`;
+						return element.id +
+							// Ensure re-rendering an element once slash commands are loaded, so the colorization can be applied.
+							`${(isRequestVM(element) || isWelcomeVM(element)) && !!this.lastSlashCommands ? '_scLoaded' : ''}` +
+							// If a response is in the process of progressive rendering, we need to ensure that it will
+							// be re-rendered so progressive rendering is restarted, even if the model wasn't updated.
+							`${isResponseVM(element) && element.renderData ? `_${this.visibleChangeCount}` : ''}`;
 					},
 				}
 			});
@@ -208,8 +214,11 @@ export class InteractiveSessionWidget extends Disposable implements IInteractive
 
 	setVisible(visible: boolean): void {
 		this.visible = visible;
+		this.visibleChangeCount++;
+		this.renderer.setVisible(visible);
+
 		if (visible) {
-			// Not sure why this is needed- the view is being rendered before it's visible, and then the list content doesn't show up
+			// Progressive rendering paused while hidden, so start it up again
 			this.onDidChangeItems();
 		}
 	}

src/vs/workbench/contrib/interactiveSession/common/interactiveSessionViewModel.ts

@@ -174,7 +174,7 @@ export class InteractiveRequestViewModel implements IInteractiveRequestViewModel
 }
 
 export class InteractiveResponseViewModel extends Disposable implements IInteractiveResponseViewModel {
-	private _changeCount = 0;
+	private _modelChangeCount = 0;
 
 	private readonly _onDidChange = this._register(new Emitter<void>());
 	readonly onDidChange = this._onDidChange.event;
@@ -185,7 +185,7 @@ export class InteractiveResponseViewModel extends Disposable implements IInterac
 	}
 
 	get id() {
-		return this._model.id + `_${this._changeCount}`;
+		return this._model.id + `_${this._modelChangeCount}`;
 	}
 
 	get providerId() {
@@ -294,7 +294,7 @@ export class InteractiveResponseViewModel extends Disposable implements IInterac
 			}
 
 			// new data -> new id, new content to render
-			this._changeCount++;
+			this._modelChangeCount++;
 			if (this.renderData) {
 				this.renderData.isFullyRendered = false;
 				this.renderData.lastRenderTime = Date.now();
@@ -309,7 +309,7 @@ export class InteractiveResponseViewModel extends Disposable implements IInterac
 	}
 
 	setVote(vote: InteractiveSessionVoteDirection): void {
-		this._changeCount++;
+		this._modelChangeCount++;
 		this._model.setVote(vote);
 	}
 }