Fix progressive rendering of updated markdown content (microsoft#191851)

Fix progressive rendering updated markdown content

Author: joyceerhl

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

@@ -452,9 +452,10 @@ export class ChatListItemRenderer extends Disposable implements ITreeRenderer<Ch
 				}
 
 				// Did this part's content change?
-				else if (!isInteractiveProgressTreeData(part) && !isInteractiveProgressTreeData(renderedPart) && !renderedPart.isFullyRendered) {
+				else if (!isInteractiveProgressTreeData(part) && !isInteractiveProgressTreeData(renderedPart)) {
 					const wordCountResult = this.getDataForProgressiveRender(element, part, renderedPart);
-					if (wordCountResult !== undefined) {
+					// Check if there are any new words to render
+					if (wordCountResult !== undefined && renderedPart.renderedWordCount !== wordCountResult?.actualWordCount) {
 						partsToRender[index] = {
 							renderedWordCount: wordCountResult.actualWordCount,
 							lastRenderTime: Date.now(),