Spell 'a text node holding its text and marks alone' once, as isPlainText

src/markdown/text-break.ts

@@ -1,5 +1,5 @@
 import type { AdfNode } from '../adf/document.ts'
-import { identicalMarks, nodeMarks } from '../adf/document.ts'
+import { identicalMarks, isPlainText, nodeMarks } from '../adf/document.ts'
 import { spellInlineLeafDirective } from './directive-syntax.ts'
 
 export const textBreakName = 'textBreak'
@@ -8,9 +8,5 @@ export const textBreakSpelling = spellInlineLeafDirective(textBreakName, '')
 
 // Whether CommonMark reads the pair back as one text node, where neither rides the carry (spec/flavour.md, Inline nodes).
 export function readsAsOne(previous: AdfNode, node: AdfNode): boolean {
-  return spelledAsText(previous) && spelledAsText(node) && identicalMarks(nodeMarks(previous), nodeMarks(node))
-}
-
-function spelledAsText(node: AdfNode): boolean {
-  return node.type === 'text' && node.attrs === undefined && node.content === undefined && node.marks?.length !== 0
+  return isPlainText(previous) && isPlainText(node) && identicalMarks(nodeMarks(previous), nodeMarks(node))
 }