Answer the stability pass: pin the deeper stack, the quoted newline and the closing fence

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

@@ -130,7 +130,6 @@ test('claims a block-level colon run with no directive to parse it', () => {
   assert.equal(code(markdownToAdf(':::\n')), 'malformed-directive')
   assert.equal(code(markdownToAdf('::Panel\n')), 'malformed-directive')
   assert.equal(code(markdownToAdf('::panel {a=1 a=2}\n')), 'malformed-directive')
-  assert.deepEqual(path(markdownToAdf('Part.\n:::x\n')), ['content', 1])
   assert.deepEqual(content(markdownToAdf(':10:30\n')), [paragraph(':10:30')])
   assert.deepEqual(content(markdownToAdf(':: two\n')), [paragraph(':: two')])
 })
@@ -141,6 +140,8 @@ test('reads the three directive forms, and names the node none of them reads bac
   assert.equal(code(markdownToAdf('Part :mention[@A]{id=b1c2}.\n')), 'unknown-directive-name')
   assert.equal(content(markdownToAdf('::rule\n')), 'unknown-directive-name: the directive name rule reads back to no node')
   assert.deepEqual(path(markdownToAdf('Part.\n\n::rule\n')), ['content', 1])
+  assert.equal(content(markdownToAdf('Part.\n:::x\n')), 'malformed-directive: a container fenced with 3 colons is unclosed')
+  assert.deepEqual(path(markdownToAdf('Part.\n:::x\n')), ['content', 1])
 })
 
 test('leaves the colon that opens no directive the text it is', () => {