Answer the architecture review: one interrupt rule both directions read

src/markdown/emit/adf-to-markdown.test.ts

@@ -267,6 +267,7 @@ test('parts a nested list the tight spelling would swallow from the block above
   const outer = (...content: AdfNode[]): AdfDocument => document({ content: [item(...content)], type: 'bulletList' })
   const ordered: AdfNode = { attrs: { order: 2 }, content: [item(text('b'))], type: 'orderedList' }
   assert.equal(markdown(adfToMarkdown(outer(text('a'), ordered))), '- a\n\n  2. b\n')
+  assert.equal(markdown(adfToMarkdown(outer(text('a'), { ...ordered, attrs: { order: 1 } }))), '- a\n  1. b\n')
   assert.equal(markdown(adfToMarkdown(outer(text('a'), { content: [item()], type: 'bulletList' }))), '- a\n\n  -\n')
   assert.equal(markdown(adfToMarkdown(outer(text('a'), { content: [item(text('b'))], type: 'bulletList' }))), '- a\n  - b\n')
 })
@@ -381,6 +382,9 @@ test('refuses a document nested deeper than the emitter carries', () => {
   let node: AdfNode = paragraph({ text: 'x', type: 'text' })
   for (let depth = 0; depth < 600; depth += 1) node = { content: [node], type: 'blockquote' }
   assert.equal(code(adfToMarkdown(document(node))), 'unsupported-nesting-depth')
+  let carried: AdfNode = paragraph({ text: 'x', type: 'text' })
+  for (let depth = 0; depth < 500; depth += 1) carried = { content: [carried], type: 'blockquote' }
+  assert.ok(adfToMarkdown(document(carried)).ok)
 })
 
 test('emits an empty list item without trailing whitespace', () => {

src/markdown/emit/adf-to-markdown.ts

@@ -7,7 +7,7 @@ import { carriesOnly, isAdfDocument } from '../../adf/document.ts'
 import { emitInlineLine } from './inline-line.ts'
 import { failure, success, type ConvertErrorPath, type Result } from '../../result.ts'
 import { fencedCodeBlock } from '../backtick-runs.ts'
-import { holdsControlCharacter, holdsEntityReference, holdsNullCharacter, isThematicBreak } from '../commonmark-grammar.ts'
+import { holdsControlCharacter, holdsEntityReference, holdsNullCharacter, isThematicBreak, markerInterruptsParagraph } from '../commonmark-grammar.ts'
 import { largestNesting } from '../../nesting.ts'
 import { spellDirectiveHeader } from './block-directive-spelling.ts'
 import { tryImage } from './image.ts'
@@ -72,8 +72,10 @@ function separationBetween(previous: PlacedBlock, next: PlacedBlock, container:
 }
 
 function interruptsParagraph(node: AdfNode): boolean {
-  if (node.type === 'orderedList') return false
-  return ((node.content ?? [])[0]?.content ?? []).length > 0
+  const items = node.content ?? []
+  const empty = (items[0]?.content ?? []).length === 0
+  if (node.type !== 'orderedList') return markerInterruptsParagraph(undefined, empty)
+  return markerInterruptsParagraph(listStart(node, items.length) ?? 0, empty)
 }
 
 function emitBlock(node: AdfNode, path: ConvertErrorPath, depth: number): Result<EmittedBlock> {