4b - the walk reports its headroom, so a list falling back to the directive form refuses at zero and the list limit stays 500

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

@@ -676,11 +676,11 @@ test('refuses input nested deeper than the parser carries', () => {
   assert.deepEqual(position(markdownToAdf(nest(['expand', ...repeated('panel'), 'expand'], 'Part.\n'))), { line: 501, offset: 5501 })
   assert.equal(code(markdownToAdf(nest(['panel', ...repeated('expand'), 'panel'], 'Part.\n'))), 'unsupported-nesting-depth')
   const listed = (levels: number): string => `${'!adf:bulletList\n!adf:listItem\n---\n'.repeat(levels)}${'!adf:/listItem\n!adf:/bulletList\n'.repeat(levels)}`
-  const lists = largestNesting / 2
-  assert.ok(markdownToAdf(listed(lists)).ok)
-  assert.equal(code(markdownToAdf(listed(lists + 1))), 'unsupported-nesting-depth')
-  assert.ok(markdownToAdf(`${'- '.repeat(lists)}a\n`).ok)
-  assert.equal(code(markdownToAdf(`${'- '.repeat(lists + 1)}a\n`)), 'unsupported-nesting-depth')
+  const directiveLists = largestNesting / 2
+  assert.ok(markdownToAdf(listed(directiveLists)).ok)
+  assert.equal(code(markdownToAdf(listed(directiveLists + 1))), 'unsupported-nesting-depth')
+  assert.ok(markdownToAdf(`${'- '.repeat(largestNesting)}a\n`).ok)
+  assert.equal(code(markdownToAdf(`${'- '.repeat(largestNesting + 1)}a\n`)), 'unsupported-nesting-depth')
 })
 
 test('decodes the backslash escapes CommonMark spells, and keeps the rest literal', () => {

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

@@ -150,7 +150,7 @@ function withContent(node: AdfNode, content: readonly AdfNode[]): AdfNode {
 function listNode(node: AdfNode, items: readonly Block[][], definitions: LinkDefinitions, path: ConvertErrorPath, depth: number): Result<AdfNode> {
   const content: AdfNode[] = []
   for (const [index, blocks] of items.entries()) {
-    const item = containerNode({ type: 'listItem' }, blocks, definitions, [...path, 'content', index], depth + 1)
+    const item = containerNode({ type: 'listItem' }, blocks, definitions, [...path, 'content', index], depth)
     if (!item.ok) return item
     content.push(item.value)
   }