Payload's defaultFeatures don't register a 'code' node, so fenced code blocks crashed the admin editor with $parseSerializedNodeImpl. Replace the bare 'code' Lexical node with a custom Payload Block ('codeBlock') exposing language + code fields, register it in the body editor, and render it as <pre><code> on the frontend. Also fill in the TextNode serialized shape (detail/mode/style) that Lexical 0.41's TextNode.updateFromJSON requires. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>