4c - the guard's spread was a class: the code block's held lines and a mark run's segments too

src/markdown/parse/blocks.test.ts

@@ -118,3 +118,7 @@ test('closes the containers a closer names past as unclosed, and crosses no list
   assert.deepEqual(kinds('!adf:rule {localId=a-1}\nPart.\n!adf:/rule\n'), ['fault', 'paragraph'])
   assert.deepEqual(kinds('!adf:rule {localId=a-1}\n!adf:/rule\n!adf:/rule\n'), ['fault', 'fault'])
 })
+
+test("releases an indented code block's held blank lines as a walk rather than as one call's arguments", () => {
+  assert.deepEqual(kinds(`    a\n${'\n'.repeat(200000)}    b\n`), ['code'])
+})

src/markdown/parse/blocks.ts

@@ -365,7 +365,8 @@ function readIndentedCodeLine(leaf: Extract<OpenLeaf, { kind: 'indented-code' }>
     return true
   }
   if (leadingColumns(line) < indentedCodeColumns) return false
-  leaf.lines.push(...leaf.held, removeColumns(line, indentedCodeColumns).text)
+  for (const held of leaf.held) leaf.lines.push(held)
+  leaf.lines.push(removeColumns(line, indentedCodeColumns).text)
   leaf.held.length = 0
   return true
 }