Add comment thread pending comment reconciliation

Fixes #196574

src/vs/workbench/contrib/comments/browser/commentsController.ts

@@ -869,8 +869,20 @@ export class CommentController implements IEditorContribution {
 		const matchedZones = this._commentWidgets.filter(zoneWidget => zoneWidget.owner === thread.owner && Range.lift(zoneWidget.commentThread.range)?.equalsRange(thread.range));
 		if (thread.isReply && matchedZones.length) {
 			this.commentService.removeContinueOnComment({ owner: thread.owner, uri: editorURI, range: thread.range, isReply: true });
-			const matchedZone = matchedZones[0];
-			matchedZone.setPendingComment(thread.body);
+			matchedZones[0].setPendingComment(thread.body);
+		} else if (matchedZones.length) {
+			this.commentService.removeContinueOnComment({ owner: thread.owner, uri: editorURI, range: thread.range, isReply: false });
+			const existingPendingComment = matchedZones[0].getPendingComments().newComment;
+			// We need to try to reconcile the existing pending comment with the incoming pending comment
+			let pendingComment: string;
+			if (!existingPendingComment || thread.body.includes(existingPendingComment)) {
+				pendingComment = thread.body;
+			} else if (existingPendingComment.includes(thread.body)) {
+				pendingComment = existingPendingComment;
+			} else {
+				pendingComment = `${existingPendingComment}\n${thread.body}`;
+			}
+			matchedZones[0].setPendingComment(pendingComment);
 		} else if (!thread.isReply) {
 			const threadStillAvailable = this.commentService.removeContinueOnComment({ owner: thread.owner, uri: editorURI, range: thread.range, isReply: false });
 			if (!threadStillAvailable) {