Answer architecture round 4: the forecast and the indent leave, a writer refuses a document whose text alone passes the bound, and the joins are the one bound left

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

@@ -456,11 +456,6 @@ test('refuses compact JSON in the carry fence without building its two-space spe
   )
 })
 
-test('refuses a directive whose CommonMark spelling would pass V8\'s longest string', () => {
-  const markdown = `!adf:blockquote\n${'>'.repeat(490)} a\\\n${'b\\\n'.repeat(560_000)}c\n!adf:/blockquote\n`
-  assert.equal(content(losslessMarkdownToAdf(markdown)), 'unsupported-node-shape: spelled as markdown, this would be longer than 536870888 characters, the longest string V8 holds')
-})
-
 test('names the node JSON an opaque carry restores alone', () => {
   const node = "unsupported-node-shape: the opaque carry holds one ADF node's JSON: this JSON is no ADF node; "
   assert.equal(content(losslessMarkdownToAdf('```adf:x\n[]\n```\n')), `${node}!adf:codeBlock {language="adf:x"} around a bare fence keeps it a code block`)

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

@@ -51,7 +51,6 @@ function readDocument(markdown: string, claims: Claims): Result<AdfDocument, Par
   )
 }
 
-// A failure naming no position stands at the start of the input, which readDocument gives it.
 function readMarkdown(markdown: string, claims: Claims): Result<AdfDocument> {
   if (typeof markdown !== 'string') return failure('not-a-string', `markdown is a string: found ${typeName(markdown)}`, [])
   const parsed = parseBlocks(markdown, claims)
@@ -263,7 +262,7 @@ function directiveNode(block: DirectiveBlock, reading: Reading, path: ConvertErr
   if (!read.ok) return read
   const built = directiveBody(read.value, block.blocks, reading, path, depth)
   if (!built.ok) return built
-  const readable = commonMarkSpelling(built.value, path, depth, { flavour: 'lossless', indent: 0, memo: reading.memo })
+  const readable = commonMarkSpelling(built.value, path, depth, { flavour: 'lossless', memo: reading.memo })
   if (readable === undefined) return built
   if (!readable.ok) return readable
   return failure('unsupported-node-shape', `${built.value.type} takes the CommonMark spelling, not the directive form`, path)