Allow deletion of orphan output nodes!

packages/lexical/src/convert/markdown/convertToMarkdown.ts

@@ -25,7 +25,7 @@ import {
 } from './utils';
 
 export function $convertToMarkdownString(): string {
-  const output = [];
+  const output: string[] = [];
   const children = $getRoot().getChildren();
 
   for (const child of children) {
@@ -56,7 +56,7 @@ function exportTopLevelElementOrDecorator(node: LexicalNode): string | null {
 }
 
 function exportChildren(node: ElementNode): string {
-  const output = [];
+  const output: string[] = [];
   const children = node.getChildren();
 
   for (const child of children) {

packages/lexical/src/nodes/JupyterOutputNode.tsx

@@ -28,6 +28,7 @@ import {
   Kernel,
 } from '@datalayer/jupyter-react';
 import { createNoKernelWarning } from './jupyterUtils';
+import { isJupyterOutputNodeOrphaned } from './JupyterOutputNodeUtils';
 
 export type SerializedJupyterOutputNode = Spread<
   {
@@ -191,7 +192,10 @@ export class JupyterOutputNode extends DecoratorNode<JSX.Element> {
 
   /** @override */
   isIsolated(): boolean {
-    return false;
+    // Treat orphaned output nodes as isolated blocks for editing purposes
+    // Return true only for orphaned nodes so they are handled as isolated blocks
+    // Normal output nodes with valid parents remain non-isolated
+    return isJupyterOutputNodeOrphaned(this);
   }
 
   /** @override */
@@ -223,7 +227,15 @@ export class JupyterOutputNode extends DecoratorNode<JSX.Element> {
 
   /** @override */
   remove(_preserveEmptyParent?: boolean): void {
-    // Do not delete JupyterOutputNode.
+    // Check if this output node is orphaned (parent input node was deleted)
+    if (isJupyterOutputNodeOrphaned(this)) {
+      // Allow deletion of orphaned output nodes
+      // Explicitly set preserveEmptyParent to false for orphaned nodes,
+      // since their parent has already been deleted and we do not want to preserve an
+      // empty parent.
+      super.remove(false);
+    }
+    // Otherwise, do not delete (output nodes with valid parents are protected)
   }
 
   removeForce(): void {

packages/lexical/src/nodes/JupyterOutputNodeUtils.ts

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2021-2023 Datalayer, Inc.
+ *
+ * MIT License
+ */
+
+import { INPUT_UUID_TO_CODE_KEY } from '../plugins/JupyterInputOutputPlugin';
+import type { JupyterOutputNode } from './JupyterOutputNode';
+
+/**
+ * Check if a JupyterOutputNode is orphaned (its parent input node was deleted).
+ *
+ * An output node is considered orphaned if:
+ * 1. Its parent input node UUID is not in the INPUT_UUID_TO_CODE_KEY map, OR
+ * 2. The output node has no parent in the Lexical tree
+ *
+ * @param outputNode - The JupyterOutputNode to check
+ * @returns true if the output node is orphaned, false otherwise
+ */
+export function isJupyterOutputNodeOrphaned(
+  outputNode: JupyterOutputNode,
+): boolean {
+  const inputNodeKey = INPUT_UUID_TO_CODE_KEY.get(
+    outputNode.getJupyterInputNodeUuid(),
+  );
+  return !inputNodeKey || !outputNode.getParent();
+}