[lexical] Refactor: Port node classes to the $config() protocol

## Description

Building on the additive $config() protocol changes in the previous commit, this
ports the node classes to `$config()` and removes the now-redundant boilerplate
static methods (`getType`, `clone`, `importJSON`, `importDOM`) that
`getStaticNodeConfig` already synthesizes at runtime, moving each node's
`importDOM` map into the `$config` `importDOM` option while leaving
`updateFromJSON`/`exportJSON`/`createDOM`/`updateDOM` in place. (It intentionally
does not adopt the separate JSON-schema serialization work — serialization
methods are unchanged.)

Ported across `lexical` (TextNode, TabNode, LineBreakNode, ParagraphNode,
RootNode, ArtificialNode), `@lexical/rich-text` (Heading, Quote),
`@lexical/link` (Link, AutoLink), `@lexical/mark`, `@lexical/hashtag`,
`@lexical/table` (Table, Row, Cell), `@lexical/code` (CodeNode,
CodeHighlightNode), `@lexical/react` and `@lexical/extension` HorizontalRule,
the playground nodes, and the examples. Decorator nodes whose constructors take
required arguments keep a minimal `clone`/`importJSON` (they must construct with
arguments). The base `LexicalNode` and the test fixtures that exist to verify
the legacy static-method path are left as-is.

- Now that a node records its own `type` via the `$config` accessor introduced
  in the previous commit, the structurally-identical `TabNode` stays nominally
  distinct from `TextNode` without the statics it previously relied on, so
  guards like `$isTabNode()` keep narrowing correctly.
- Nodes relying on the synthesized `clone` need a zero-argument constructor, so
  key-only/leading parameters were given explicit defaults (or redundant
  pure-delegation constructors were removed) so `Node.length === 0`.
- Fixed code that relied on `TextNode` being assignable to `TabNode`:
  `$getFirstCodeNodeOfLine` is now generic over its anchor type.
- `__type` is now `readonly` (it is only ever assigned once, in the
  constructor); `@lexical/yjs`'s generic property writer casts through a mutable
  record accordingly (it never actually writes `__type`, which is intrinsic and
  filtered out by its equal-value guard).

Tests:
- Clone tests use the public `$cloneWithProperties` helper instead of manually
  pairing `clone()` with `afterCloneFrom()`.
- DOM-conversion tests use a new shared `$runDOMConversion` util that drives the
  editor's registered conversion cache (the paste path) rather than calling a
  node's static `importDOM()` directly.

## Test plan

`pnpm run tsc`, `pnpm run flow`, ESLint, and Prettier all pass. The full unit
suite is green: 3728 passed / 1 skipped across `--project unit` and
`--project scripts-unit`.

Author: claude

examples/node-replacement/src/nodes/CustomParagraphNode.ts

@@ -5,22 +5,11 @@
  * LICENSE file in the root directory of this source tree.
  *
  */
-import {
-  $applyNodeReplacement,
-  EditorConfig,
-  ParagraphNode,
-  SerializedParagraphNode,
-} from 'lexical';
+import {$applyNodeReplacement, EditorConfig, ParagraphNode} from 'lexical';
 
 export class CustomParagraphNode extends ParagraphNode {
-  static getType() {
-    return 'custom-paragraph';
-  }
-  static clone(node: CustomParagraphNode): CustomParagraphNode {
-    return new CustomParagraphNode(node.__key);
-  }
-  static importJSON(json: SerializedParagraphNode): CustomParagraphNode {
-    return $createCustomParagraphNode().updateFromJSON(json);
+  $config() {
+    return this.config('custom-paragraph', {extends: ParagraphNode});
   }
   createDOM(config: EditorConfig) {
     const el = super.createDOM(config);

examples/vanilla-js-plugin/src/emoji-plugin/EmojiNode.ts

@@ -24,8 +24,8 @@ const BASE_EMOJI_URI = new URL(`@emoji-datasource-facebook/`, import.meta.url)
 export class EmojiNode extends TextNode {
   __unifiedID: string;
 
-  static getType(): string {
-    return 'emoji';
+  $config() {
+    return this.config('emoji', {extends: TextNode});
   }
 
   static clone(node: EmojiNode): EmojiNode {

packages/lexical-code-core/src/CodeHighlightNode.ts

@@ -47,16 +47,8 @@ export class CodeHighlightNode extends TextNode {
     this.__highlightType = highlightType;
   }
 
-  static getType(): string {
-    return 'code-highlight';
-  }
-
-  static clone(node: CodeHighlightNode): CodeHighlightNode {
-    return new CodeHighlightNode(
-      node.__text,
-      node.__highlightType || undefined,
-      node.__key,
-    );
+  $config() {
+    return this.config('code-highlight', {extends: TextNode});
   }
 
   afterCloneFrom(prevNode: this): void {
@@ -110,12 +102,6 @@ export class CodeHighlightNode extends TextNode {
     return update;
   }
 
-  static importJSON(
-    serializedNode: SerializedCodeHighlightNode,
-  ): CodeHighlightNode {
-    return $createCodeHighlightNode().updateFromJSON(serializedNode);
-  }
-
   updateFromJSON(
     serializedNode: LexicalUpdateJSON<SerializedCodeHighlightNode>,
   ): this {

packages/lexical-code-core/src/CodeNode.ts

@@ -8,7 +8,6 @@
 
 import type {CodeExtension} from './CodeExtension';
 import type {
-  DOMConversionMap,
   DOMConversionOutput,
   DOMExportOutput,
   EditorConfig,
@@ -88,15 +87,80 @@ export class CodeNode extends ElementNode {
   /** @internal */
   __isSyntaxHighlightSupported: boolean;
 
-  static getType(): string {
-    return 'code';
-  }
+  $config() {
+    return this.config('code', {
+      extends: ElementNode,
+      importDOM: {
+        // Typically <pre> is used for code blocks, and <code> for inline code styles
+        // but if it's a multi line <code> we'll create a block. Pass through to
+        // inline format handled by TextNode otherwise.
+        code: (node: Node) => {
+          const isMultiLine =
+            node.textContent != null &&
+            (/\r?\n/.test(node.textContent) || hasChildDOMNodeTag(node, 'BR'));
+
+          return isMultiLine
+            ? {
+                conversion: $convertPreElement,
+                priority: 1,
+              }
+            : null;
+        },
+        div: () => ({
+          conversion: $convertDivElement,
+          priority: 1,
+        }),
+        pre: () => ({
+          conversion: $convertPreElement,
+          priority: 0,
+        }),
+        table: (node: Node) => {
+          const table = node;
+          // domNode is a <table> since we matched it by nodeName
+          if (isGitHubCodeTable(table as HTMLTableElement)) {
+            return {
+              conversion: $convertTableElement,
+              priority: 3,
+            };
+          }
+          return null;
+        },
+        td: (node: Node) => {
+          // element is a <td> since we matched it by nodeName
+          const td = node as HTMLTableCellElement;
+          const table: HTMLTableElement | null = td.closest('table');
+
+          if (isGitHubCodeCell(td) || (table && isGitHubCodeTable(table))) {
+            // Return a no-op if it's a table cell in a code table, but not a code line.
+            // Otherwise it'll fall back to the T
+            return {
+              conversion: convertCodeNoop,
+              priority: 3,
+            };
+          }
 
-  static clone(node: CodeNode): CodeNode {
-    return new CodeNode(node.__language, node.__key);
+          return null;
+        },
+        tr: (node: Node) => {
+          // element is a <tr> since we matched it by nodeName
+          const tr = node as HTMLTableCellElement;
+          const table: HTMLTableElement | null = tr.closest('table');
+          if (table && isGitHubCodeTable(table)) {
+            return {
+              conversion: convertCodeNoop,
+              priority: 3,
+            };
+          }
+          return null;
+        },
+      },
+    });
   }
 
-  constructor(language?: string | null | undefined, key?: NodeKey) {
+  // `language` carries an explicit `undefined` default so the constructor
+  // reports zero required arguments and `$config` can synthesize the static
+  // `clone` from the no-argument constructor.
+  constructor(language: string | null | undefined = undefined, key?: NodeKey) {
     super(key);
     this.__language = language || undefined;
     this.__isSyntaxHighlightSupported = false;
@@ -207,77 +271,6 @@ export class CodeNode extends ElementNode {
     return {element};
   }
 
-  static importDOM(): DOMConversionMap | null {
-    return {
-      // Typically <pre> is used for code blocks, and <code> for inline code styles
-      // but if it's a multi line <code> we'll create a block. Pass through to
-      // inline format handled by TextNode otherwise.
-      code: (node: Node) => {
-        const isMultiLine =
-          node.textContent != null &&
-          (/\r?\n/.test(node.textContent) || hasChildDOMNodeTag(node, 'BR'));
-
-        return isMultiLine
-          ? {
-              conversion: $convertPreElement,
-              priority: 1,
-            }
-          : null;
-      },
-      div: () => ({
-        conversion: $convertDivElement,
-        priority: 1,
-      }),
-      pre: () => ({
-        conversion: $convertPreElement,
-        priority: 0,
-      }),
-      table: (node: Node) => {
-        const table = node;
-        // domNode is a <table> since we matched it by nodeName
-        if (isGitHubCodeTable(table as HTMLTableElement)) {
-          return {
-            conversion: $convertTableElement,
-            priority: 3,
-          };
-        }
-        return null;
-      },
-      td: (node: Node) => {
-        // element is a <td> since we matched it by nodeName
-        const td = node as HTMLTableCellElement;
-        const table: HTMLTableElement | null = td.closest('table');
-
-        if (isGitHubCodeCell(td) || (table && isGitHubCodeTable(table))) {
-          // Return a no-op if it's a table cell in a code table, but not a code line.
-          // Otherwise it'll fall back to the T
-          return {
-            conversion: convertCodeNoop,
-            priority: 3,
-          };
-        }
-
-        return null;
-      },
-      tr: (node: Node) => {
-        // element is a <tr> since we matched it by nodeName
-        const tr = node as HTMLTableCellElement;
-        const table: HTMLTableElement | null = tr.closest('table');
-        if (table && isGitHubCodeTable(table)) {
-          return {
-            conversion: convertCodeNoop,
-            priority: 3,
-          };
-        }
-        return null;
-      },
-    };
-  }
-
-  static importJSON(serializedNode: SerializedCodeNode): CodeNode {
-    return $createCodeNode().updateFromJSON(serializedNode);
-  }
-
   updateFromJSON(serializedNode: LexicalUpdateJSON<SerializedCodeNode>): this {
     return super
       .updateFromJSON(serializedNode)

packages/lexical-code-core/src/FlatStructureUtils.ts

@@ -14,6 +14,7 @@ import type {
   RangeSelection,
   SiblingCaret,
   TabNode,
+  TextNode,
 } from 'lexical';
 
 import invariant from '@lexical/internal/invariant';
@@ -33,11 +34,15 @@ import {
   $isCodeHighlightNode,
 } from './CodeHighlightNode';
 
-function $getLastMatchingCodeNode<D extends CaretDirection>(
-  anchor: CodeHighlightNode | TabNode | LineBreakNode,
-  direction: D,
-): CodeHighlightNode | TabNode | LineBreakNode {
-  let matchingNode: CodeHighlightNode | TabNode | LineBreakNode = anchor;
+// The anchor is generic (rather than the narrower
+// `CodeHighlightNode | TabNode | LineBreakNode`) because callers may have only
+// narrowed as far as TextNode; the matched siblings are always
+// CodeHighlightNode/TabNode, and an unmatched anchor is returned unchanged.
+function $getLastMatchingCodeNode<
+  T extends TextNode | LineBreakNode,
+  D extends CaretDirection,
+>(anchor: T, direction: D): T | CodeHighlightNode | TabNode {
+  let matchingNode: T | CodeHighlightNode | TabNode = anchor;
   for (
     let caret: null | SiblingCaret<LexicalNode, D> = $getSiblingCaret(
       anchor,
@@ -51,15 +56,15 @@ function $getLastMatchingCodeNode<D extends CaretDirection>(
   return matchingNode;
 }
 
-export function $getFirstCodeNodeOfLine(
-  anchor: CodeHighlightNode | TabNode | LineBreakNode,
-): CodeHighlightNode | TabNode | LineBreakNode {
+export function $getFirstCodeNodeOfLine<T extends TextNode | LineBreakNode>(
+  anchor: T,
+): T | CodeHighlightNode | TabNode {
   return $getLastMatchingCodeNode(anchor, 'previous');
 }
 
-export function $getLastCodeNodeOfLine(
-  anchor: CodeHighlightNode | TabNode | LineBreakNode,
-): CodeHighlightNode | TabNode | LineBreakNode {
+export function $getLastCodeNodeOfLine<T extends TextNode | LineBreakNode>(
+  anchor: T,
+): T | CodeHighlightNode | TabNode {
   return $getLastMatchingCodeNode(anchor, 'next');
 }
 

packages/lexical-extension/src/HorizontalRuleExtension.ts

@@ -7,7 +7,6 @@
  */
 
 import type {
-  DOMConversionMap,
   DOMConversionOutput,
   DOMExportOutput,
   EditorConfig,
@@ -49,27 +48,20 @@ export const INSERT_HORIZONTAL_RULE_COMMAND: LexicalCommand<void> =
   createCommand('INSERT_HORIZONTAL_RULE_COMMAND');
 
 export class HorizontalRuleNode extends DecoratorNode<unknown> {
-  static getType(): string {
-    return 'horizontalrule';
-  }
-
-  static clone(node: HorizontalRuleNode): HorizontalRuleNode {
-    return new HorizontalRuleNode(node.__key);
-  }
-
-  static importJSON(
-    serializedNode: SerializedHorizontalRuleNode,
-  ): HorizontalRuleNode {
-    return $createHorizontalRuleNode().updateFromJSON(serializedNode);
-  }
-
-  static importDOM(): DOMConversionMap | null {
-    return {
-      hr: () => ({
-        conversion: $convertHorizontalRuleElement,
-        priority: 0,
-      }),
-    };
+  $config() {
+    // `extends` is intentionally left to the runtime default (the prototype
+    // parent) rather than declared explicitly: the deprecated
+    // `@lexical/react` HorizontalRuleNode subclasses this one and reuses the
+    // same 'horizontalrule' type, so both `$config()` overrides must infer a
+    // matching shape.
+    return this.config('horizontalrule', {
+      importDOM: {
+        hr: () => ({
+          conversion: $convertHorizontalRuleElement,
+          priority: 0,
+        }),
+      },
+    });
   }
 
   exportDOM(): DOMExportOutput {

packages/lexical-hashtag/src/LexicalHashtagNode.ts

@@ -6,19 +6,15 @@
  *
  */
 
-import type {EditorConfig, LexicalNode, SerializedTextNode} from 'lexical';
+import type {EditorConfig, LexicalNode} from 'lexical';
 
 import {addClassNamesToElement} from '@lexical/utils';
 import {$applyNodeReplacement, TextNode} from 'lexical';
 
 /** @noInheritDoc */
 export class HashtagNode extends TextNode {
-  static getType(): string {
-    return 'hashtag';
-  }
-
-  static clone(node: HashtagNode): HashtagNode {
-    return new HashtagNode(node.__text, node.__key);
+  $config() {
+    return this.config('hashtag', {extends: TextNode});
   }
 
   createDOM(config: EditorConfig): HTMLElement {
@@ -27,10 +23,6 @@ export class HashtagNode extends TextNode {
     return element;
   }
 
-  static importJSON(serializedNode: SerializedTextNode): HashtagNode {
-    return $createHashtagNode().updateFromJSON(serializedNode);
-  }
-
   canInsertTextBefore(): boolean {
     return false;
   }