4.1: an iterative canonical serializer

AGENTS.md

@@ -23,8 +23,8 @@ backticks read back as a fence — so a parse succeeding does not imply a spella
 `corpus/commonmark-spec/exceptions.json` names those.
 
 "Equals" is structural equality over editor-normal ADF — adjacent text nodes with identical marks
-merged, JSON number semantics, an empty attrs object, marks array or content array the absent
-key — the only domain markdown can restore.
+and no attributes merged, JSON number semantics, an empty attrs object, marks array or content
+array the absent key — the only domain markdown can restore.
 
 Round-trip equality is a property tested over a corpus, not a claim made in prose.
 

corpus/round-trip/combinations/carry-text-attributes.json

@@ -0,0 +1,57 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "attrs": {
+            "localId": "01a0a067-68cf-78af-abd6-c660ec0d189b"
+          },
+          "text": "Owner",
+          "type": "text"
+        },
+        {
+          "text": " signs off.",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "Signed by ",
+          "type": "text"
+        },
+        {
+          "attrs": {
+            "localId": "01a0a067-68d2-787e-afc5-2459776aa029"
+          },
+          "text": "the owner",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "attrs": {
+            "localId": "01a0a067-68d5-7372-9962-29a039654056"
+          },
+          "text": "One ",
+          "type": "text"
+        },
+        {
+          "attrs": {
+            "localId": "01a0a067-68d5-7372-9962-29a039654056"
+          },
+          "text": "anchor",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}

corpus/round-trip/combinations/carry-text-attributes.md

@@ -0,0 +1,5 @@
+:adf{json="{\"attrs\":{\"localId\":\"01a0a067-68cf-78af-abd6-c660ec0d189b\"},\"text\":\"Owner\",\"type\":\"text\"}"} signs off.
+
+Signed by :adf{json="{\"attrs\":{\"localId\":\"01a0a067-68d2-787e-afc5-2459776aa029\"},\"text\":\"the owner\",\"type\":\"text\"}"}
+
+:adf{json="{\"attrs\":{\"localId\":\"01a0a067-68d5-7372-9962-29a039654056\"},\"text\":\"One \",\"type\":\"text\"}"}:adf{json="{\"attrs\":{\"localId\":\"01a0a067-68d5-7372-9962-29a039654056\"},\"text\":\"anchor\",\"type\":\"text\"}"}

spec/flavour.md

@@ -404,10 +404,10 @@ Right.
 Attributes and the carry fallback read as in the block sections, the carry in its inline form. Of
 the nodes below, `emoji`, `mention` and `status` spell their `text` attribute in the content slot
 as plain text: `[]` is the empty string, absent content is the absent attribute, non-empty content
-parsing to anything but one unmarked text node — adjacent identical-mark text nodes merged first —
-is a named error, and so is a `text` key in `{attrs}`. An enclosing mark spelling does not reach
-into the slot. The rest take no content, `:text` included; content on a node that takes none is a
-named error.
+parsing to anything but one unmarked text node — adjacent text nodes with identical marks and no
+attributes merged first — is a named error, and so is a `text` key in `{attrs}`. An enclosing mark
+spelling does not reach into the slot. The rest take no content, `:text` included; content on a
+node that takes none is a named error.
 
 - `date` — Attributes: `localId` (string), `timestamp` (string, epoch milliseconds).
 - `emoji` — Attributes: `id` (string), `localId` (string), `shortName` (string, `:name:`), `text`
@@ -434,10 +434,10 @@ CommonMark strips or refuses one — a block's inline content edges, either side
 an em, strong or strike spelling's inner edges, a pipe cell's edges — is spelled
 `:text{text="…"}`, the reserved key carrying the node's text, escaped by the attribute grammar
 and never literal: pipe cells trim and pad. The emitter wraps the whitespace run alone and leaves
-the rest plain text; `markdownToAdf` merges adjacent text nodes carrying identical marks
-(AGENTS.md §2). Input reads that spelling alone: the value is one run of spaces and tabs, or one
-run of newlines, and anything else — a mixed run, or text CommonMark carries plainly — is a named
-error.
+the rest plain text; `markdownToAdf` merges adjacent text nodes carrying identical marks and no
+attributes (AGENTS.md §2). Input reads that spelling alone: the value is one run of spaces and
+tabs, or one run of newlines, and anything else — a mixed run, or text CommonMark carries plainly —
+is a named error.
 
 ```
 :text{text="  "}Two leading spaces held, and one text node split:text{text="\n"}over two lines.

src/adf/document.ts

@@ -52,8 +52,8 @@ export function attributeNestingMessage(key: string, type: string, levels: numbe
 }
 
 export function carriesOnly(node: AdfNode, attributes: readonly string[]): boolean {
-  if ((node.marks ?? []).length > 0 || node.text !== undefined) return false
-  return holdsOnly(node.attrs ?? {}, attributes)
+  if (nodeMarks(node).length > 0 || node.text !== undefined) return false
+  return holdsOnly(nodeAttrs(node), attributes)
 }
 
 // Depth is the walks' business, not the shape's: the guard waves a deep document through as blocks and marks do.
@@ -72,6 +72,18 @@ export function isAdfMark(value: unknown): value is AdfMark {
   return !('attrs' in value) || isAttributes(value['attrs'])
 }
 
+export function nodeAttrs(node: { attrs?: AdfAttributes }): Readonly<AdfAttributes> {
+  return node.attrs ?? {}
+}
+
+export function nodeContent(node: { content?: AdfNode[] }): readonly AdfNode[] {
+  return node.content ?? []
+}
+
+export function nodeMarks(node: { marks?: AdfMark[] }): readonly AdfMark[] {
+  return node.marks ?? []
+}
+
 function isNodeArray(value: readonly unknown[]): value is readonly AdfNode[] {
   const pending: unknown[] = [...value]
   while (pending.length > 0) {
@@ -95,23 +107,23 @@ function nestingFault(nodes: readonly AdfNode[]): ConvertFault | undefined {
   while (pending.length > 0) {
     const node = pending.pop()
     if (node === undefined) continue
-    const fault = attributesFault(node.attrs, node.type) ?? marksFault(node.marks)
+    const fault = attributesFault(nodeAttrs(node), node.type) ?? marksFault(nodeMarks(node))
     if (fault !== undefined) return fault
-    pending.push(...(node.content ?? []))
+    pending.push(...nodeContent(node))
   }
   return undefined
 }
 
-function marksFault(marks: readonly AdfMark[] | undefined): ConvertFault | undefined {
-  for (const mark of marks ?? []) {
-    const fault = attributesFault(mark.attrs, mark.type, markAttributeNesting)
+function marksFault(marks: readonly AdfMark[]): ConvertFault | undefined {
+  for (const mark of marks) {
+    const fault = attributesFault(nodeAttrs(mark), mark.type, markAttributeNesting)
     if (fault !== undefined) return fault
   }
   return undefined
 }
 
-function attributesFault(attrs: AdfAttributes | undefined, type: string, levels: number = largestNesting): ConvertFault | undefined {
-  for (const [key, value] of Object.entries(attrs ?? {})) {
+function attributesFault(attrs: AdfAttributes, type: string, levels: number = largestNesting): ConvertFault | undefined {
+  for (const [key, value] of Object.entries(attrs)) {
     if (overNested(value, levels)) return { code: 'unsupported-nesting-depth', message: attributeNestingMessage(key, type, levels) }
   }
   return undefined

src/adf/editor-normal.test.ts

@@ -0,0 +1,77 @@
+import assert from 'node:assert/strict'
+import test from 'node:test'
+
+import type { AdfNode } from './document.ts'
+import type { JsonValue } from '../json-value.ts'
+import { toEditorNormal } from './editor-normal.ts'
+
+test('merges adjacent text nodes carrying identical marks, at every level', () => {
+  const content: AdfNode[] = [
+    { text: 'a', type: 'text' },
+    { text: 'b', type: 'text' },
+    { marks: [{ type: 'strong' }], text: 'c', type: 'text' },
+    { marks: [{ attrs: {}, type: 'strong' }], text: 'd', type: 'text' },
+    { type: 'hardBreak' },
+    { text: 'e', type: 'text' },
+    { attrs: { localId: '01a0a06b-5281-7f27-9022-8d3a74b0ab0d' }, text: 'f', type: 'text' },
+    { text: 'g', type: 'text' },
+    { attrs: {}, text: 'h', type: 'text' },
+  ]
+  assert.deepEqual(toEditorNormal({ content: [{ attrs: { panelType: 'info' }, content: [{ content, type: 'paragraph' }], type: 'panel' }], type: 'doc', version: 1 }), {
+    content: [
+      {
+        attrs: { panelType: 'info' },
+        content: [
+          {
+            content: [
+              { text: 'ab', type: 'text' },
+              { marks: [{ type: 'strong' }], text: 'cd', type: 'text' },
+              { type: 'hardBreak' },
+              { text: 'e', type: 'text' },
+              { attrs: { localId: '01a0a06b-5281-7f27-9022-8d3a74b0ab0d' }, text: 'f', type: 'text' },
+              { text: 'gh', type: 'text' },
+            ],
+            type: 'paragraph',
+          },
+        ],
+        type: 'panel',
+      },
+    ],
+    type: 'doc',
+    version: 1,
+  })
+})
+
+test('reads negative zero as zero, as JSON does', () => {
+  const marks = [{ attrs: { size: -0 }, type: 'border' }]
+  assert.deepEqual(
+    toEditorNormal({ content: [{ attrs: { a: -0, b: [{ c: -0 }, null, 'd'] }, content: [{ marks, text: 'x', type: 'text' }], type: 'paragraph' }], type: 'doc', version: -0 }),
+    { content: [{ attrs: { a: 0, b: [{ c: 0 }, null, 'd'] }, content: [{ marks: [{ attrs: { size: 0 }, type: 'border' }], text: 'x', type: 'text' }], type: 'paragraph' }], type: 'doc', version: 0 },
+  )
+})
+
+test('reads an empty attrs object, marks array or content array as the absent key', () => {
+  const paragraph: AdfNode = { attrs: {}, content: [{ attrs: {}, marks: [], text: 'a', type: 'text' }, { marks: [{ attrs: {}, type: 'em' }], text: 'b', type: 'text' }], marks: [], type: 'paragraph' }
+  assert.deepEqual(toEditorNormal({ content: [paragraph, { content: [], type: 'rule' }], type: 'doc', version: 1 }), {
+    content: [{ content: [{ text: 'a', type: 'text' }, { marks: [{ type: 'em' }], text: 'b', type: 'text' }], type: 'paragraph' }, { type: 'rule' }],
+    type: 'doc',
+    version: 1,
+  })
+  assert.deepEqual(toEditorNormal({ content: [], type: 'doc', version: 1 }), { type: 'doc', version: 1 })
+})
+
+test('normalizes blocks and mark attributes nesting far past the levels a recursive walk survives', () => {
+  const levels = 100000
+  let node: AdfNode = { content: [], type: 'paragraph' }
+  for (let level = 0; level < levels; level += 1) node = { content: [node], type: 'blockquote' }
+  let normal = toEditorNormal({ content: [node], type: 'doc', version: 1 }).content?.[0]
+  let depth = 0
+  for (; normal?.content !== undefined; depth += 1) normal = normal.content[0]
+  assert.equal(depth, levels)
+  assert.deepEqual(normal, { type: 'paragraph' })
+  let deep: JsonValue = 1
+  for (let level = 0; level < 2 * levels; level += 1) deep = [deep]
+  const marks = [{ attrs: { deep }, type: 'textColor' }]
+  const merged = toEditorNormal({ content: [{ content: [{ marks, text: 'a', type: 'text' }, { marks, text: 'b', type: 'text' }], type: 'paragraph' }], type: 'doc', version: 1 })
+  assert.deepEqual(merged.content?.[0]?.content?.map((text) => text.text), ['ab'])
+})

src/adf/editor-normal.ts

@@ -1,16 +1,21 @@
-import type { AdfMark, AdfNode } from './document.ts'
+import type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from './document.ts'
+import type { JsonValue } from '../json-value.ts'
+import { nodeAttrs, nodeContent, nodeMarks } from './document.ts'
 import { serializeCanonicalJson } from '../canonical-json.ts'
 
+type JsonContainer = JsonValue[] | { [key: string]: JsonValue }
+
+type NodeHolder = { content?: AdfNode[] }
+
 export function sameMark(candidate: AdfMark, mark: AdfMark): boolean {
   return markKey(candidate) === markKey(mark)
 }
 
-// AGENTS.md §2: adjacent text nodes carrying identical marks are one node.
 export function mergeAdjacentText(nodes: readonly AdfNode[]): AdfNode[] {
   const merged: AdfNode[] = []
   for (const node of nodes) {
     const previous = merged[merged.length - 1]
-    if (previous !== undefined && previous.type === 'text' && node.type === 'text' && sameMarks(previous, node)) {
+    if (previous !== undefined && mergesText(previous) && mergesText(node) && sameMarks(previous, node)) {
       merged[merged.length - 1] = { ...previous, text: `${previous.text ?? ''}${node.text ?? ''}` }
       continue
     }
@@ -19,8 +24,61 @@ export function mergeAdjacentText(nodes: readonly AdfNode[]): AdfNode[] {
   return merged
 }
 
+export function toEditorNormal(document: AdfDocument): AdfDocument {
+  const normal: AdfDocument = { type: document.type, version: Object.is(document.version, -0) ? 0 : document.version }
+  const pending: { holder: NodeHolder; source: NodeHolder }[] = [{ holder: normal, source: document }]
+  for (let entry = pending.pop(); entry !== undefined; entry = pending.pop()) {
+    const content = mergeAdjacentText(nodeContent(entry.source))
+    if (content.length === 0) continue
+    entry.holder.content = content.map((source) => {
+      const holder = normalNode(source)
+      pending.push({ holder, source })
+      return holder
+    })
+  }
+  return normal
+}
+
+function normalNode(node: AdfNode): AdfNode {
+  const normal: AdfNode = { type: node.type }
+  const attrs = normalAttributes(nodeAttrs(node))
+  if (attrs !== undefined) normal.attrs = attrs
+  const marks = nodeMarks(node).map(normalMark)
+  if (marks.length > 0) normal.marks = marks
+  if (node.text !== undefined) normal.text = node.text
+  return normal
+}
+
+function normalMark(mark: AdfMark): AdfMark {
+  const attrs = normalAttributes(nodeAttrs(mark))
+  return attrs === undefined ? { type: mark.type } : { attrs, type: mark.type }
+}
+
+function normalAttributes(attrs: AdfAttributes): AdfAttributes | undefined {
+  if (Object.keys(attrs).length === 0) return undefined
+  const normal = { ...attrs }
+  const pending: JsonContainer[] = [normal]
+  for (let held = pending.pop(); held !== undefined; held = pending.pop()) {
+    if (Array.isArray(held)) for (const [index, value] of held.entries()) held[index] = normalValue(value, pending)
+    else for (const [key, value] of Object.entries(held)) held[key] = normalValue(value, pending)
+  }
+  return normal
+}
+
+function normalValue(value: JsonValue, pending: JsonContainer[]): JsonValue {
+  if (Object.is(value, -0)) return 0
+  if (value === null || typeof value !== 'object') return value
+  const copy = Array.isArray(value) ? [...value] : { ...value }
+  pending.push(copy)
+  return copy
+}
+
+function mergesText(node: AdfNode): boolean {
+  return node.type === 'text' && Object.keys(nodeAttrs(node)).length === 0
+}
+
 function sameMarks(previous: AdfNode, node: AdfNode): boolean {
-  return marksKey(previous.marks ?? []) === marksKey(node.marks ?? [])
+  return marksKey(nodeMarks(previous)) === marksKey(nodeMarks(node))
 }
 
 function marksKey(marks: readonly AdfMark[]): string {
@@ -28,5 +86,5 @@ function marksKey(marks: readonly AdfMark[]): string {
 }
 
 function markKey(mark: AdfMark): string {
-  return `${mark.type} ${serializeCanonicalJson(mark.attrs ?? {}, 'compact')}`
+  return `${mark.type} ${serializeCanonicalJson(nodeAttrs(mark), 'compact')}`
 }

src/canonical-json.test.ts

@@ -1,6 +1,7 @@
 import assert from 'node:assert/strict'
 import test from 'node:test'
 
+import type { JsonValue } from './json-value.ts'
 import { serializeCanonicalJson } from './canonical-json.ts'
 
 test('sorts object keys recursively', () => {
@@ -39,3 +40,15 @@ test('leaves non-ASCII raw', () => {
 test('spells scalars in canonical JSON', () => {
   assert.equal(serializeCanonicalJson([null, true, false, 0, -1.5, 'a"b'], 'compact'), '[null,true,false,0,-1.5,"a\\"b"]')
 })
+
+test('spells a value nesting far past the levels a recursive walk survives', () => {
+  const levels = 200000
+  let array: JsonValue = 1
+  let object: JsonValue = 1
+  for (let level = 0; level < levels; level += 1) {
+    array = [array]
+    object = { a: object }
+  }
+  assert.equal(serializeCanonicalJson(array, 'compact'), `${'['.repeat(levels)}1${']'.repeat(levels)}`)
+  assert.equal(serializeCanonicalJson(object, 'compact'), `${'{"a":'.repeat(levels)}1${'}'.repeat(levels)}`)
+})

src/canonical-json.ts

@@ -2,28 +2,42 @@ import type { JsonValue } from './json-value.ts'
 
 export type JsonSpelling = 'compact' | 'two-space'
 
+type Member = { label: string; value: JsonValue }
+
+type Pending = string | { depth: number; value: JsonValue }
+
 export function serializeCanonicalJson(value: JsonValue, spelling: JsonSpelling): string {
-  return serialize(value, spelling === 'compact' ? '' : '  ', 0)
+  const indent = spelling === 'compact' ? '' : '  '
+  const text: string[] = []
+  const pending: Pending[] = [{ depth: 0, value }]
+  for (let next = pending.pop(); next !== undefined; next = pending.pop()) {
+    if (typeof next === 'string') {
+      text.push(next)
+      continue
+    }
+    const { depth, value: held } = next
+    if (Array.isArray(held)) schedule(pending, '[', held.map((item) => ({ label: '', value: item })), ']', indent, depth)
+    else if (held !== null && typeof held === 'object') schedule(pending, '{', objectMembers(held, indent), '}', indent, depth)
+    else text.push(JSON.stringify(held))
+  }
+  return text.join('')
 }
 
-function serialize(value: JsonValue, indent: string, depth: number): string {
-  if (Array.isArray(value)) {
-    if (value.length === 0) return '[]'
-    const items = value.map((item) => serialize(item, indent, depth + 1))
-    return `[${join(items, indent, depth)}]`
-  }
-  if (value !== null && typeof value === 'object') {
-    const keys = Object.keys(value).sort()
-    if (keys.length === 0) return '{}'
+function objectMembers(value: { [key: string]: JsonValue }, indent: string): Member[] {
   const separator = indent === '' ? ':' : ': '
-    const entries = keys.map((key) => `${JSON.stringify(key)}${separator}${serialize(value[key] ?? null, indent, depth + 1)}`)
-    return `{${join(entries, indent, depth)}}`
-  }
-  return JSON.stringify(value)
+  return Object.keys(value)
+    .sort()
+    .map((key) => ({ label: `${JSON.stringify(key)}${separator}`, value: value[key] ?? null }))
 }
 
-function join(parts: readonly string[], indent: string, depth: number): string {
-  if (indent === '') return parts.join(',')
-  const inner = `\n${indent.repeat(depth + 1)}`
-  return `${inner}${parts.join(`,${inner}`)}\n${indent.repeat(depth)}`
+function schedule(pending: Pending[], open: string, members: readonly Member[], close: string, indent: string, depth: number): void {
+  if (members.length === 0) {
+    pending.push(`${open}${close}`)
+    return
+  }
+  const inner = indent === '' ? '' : `\n${indent.repeat(depth + 1)}`
+  const scheduled: Pending[] = []
+  for (const [index, member] of members.entries()) scheduled.push(`${index === 0 ? open : ','}${inner}${member.label}`, { depth: depth + 1, value: member.value })
+  scheduled.push(indent === '' ? close : `\n${indent.repeat(depth)}${close}`)
+  for (const item of scheduled.reverse()) pending.push(item)
 }

src/corpus.test.ts

@@ -9,6 +9,7 @@ import { isAdfDocument } from './adf/document.ts'
 import { isJsonValue } from './json-value.ts'
 import { markdownToAdf } from './markdown/parse/markdown-to-adf.ts'
 import { serializeCanonicalJson } from './canonical-json.ts'
+import { toEditorNormal } from './adf/editor-normal.ts'
 
 const corpusRoot = join(dirname(fileURLToPath(import.meta.url)), '..', 'corpus')
 const errorsRoot = join(corpusRoot, 'errors')
@@ -95,7 +96,7 @@ for (const directory of roundTripDirectories) {
       assert.ok(isAdfDocument(expected), `${name}.json is not an ADF document`)
       const result = markdownToAdf(readFileSync(join(roundTripRoot, directory, `${name}.md`), 'utf8'))
       assert.ok(result.ok, result.ok ? '' : `${result.error.code}: ${result.error.message}`)
-      assert.deepEqual(result.value, expected)
+      assert.deepEqual(toEditorNormal(result.value), expected)
     })
   }
 }
@@ -184,12 +185,12 @@ for (const name of pairedNames(normalizationRoot, '.md', '.json')) {
     assert.ok(isAdfDocument(expected), `${name}.json is not an ADF document`)
     const result = markdownToAdf(readFileSync(join(normalizationRoot, `${name}.md`), 'utf8'))
     assert.ok(result.ok, result.ok ? '' : `${result.error.code}: ${result.error.message}`)
-    assert.deepEqual(result.value, expected)
+    assert.deepEqual(toEditorNormal(result.value), expected)
     const emitted = adfToMarkdown(result.value)
     assert.ok(emitted.ok, emitted.ok ? '' : `${emitted.error.code}: ${emitted.error.message}`)
     const again = markdownToAdf(emitted.value)
     assert.ok(again.ok, again.ok ? '' : `${again.error.code}: ${again.error.message}`)
-    assert.deepEqual(again.value, expected)
+    assert.deepEqual(toEditorNormal(again.value), expected)
   })
 }
 

src/markdown/block-directive-marks.ts

@@ -1,13 +1,13 @@
 import type { AdfMark } from '../adf/document.ts'
 import type { JsonValue } from '../json-value.ts'
-import { isAdfMark } from '../adf/document.ts'
+import { isAdfMark, nodeAttrs } from '../adf/document.ts'
 import { serializeCanonicalJson } from '../canonical-json.ts'
 
 export const marksAttribute = 'marks'
 
 export function markValues(marks: readonly AdfMark[]): JsonValue {
   return marks.map((mark) => {
-    const attrs = mark.attrs ?? {}
+    const attrs = nodeAttrs(mark)
     return Object.keys(attrs).length === 0 ? { type: mark.type } : { attrs, type: mark.type }
   })
 }

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

@@ -6,6 +6,7 @@ import type { JsonValue } from '../../json-value.ts'
 import type { Result } from '../../result.ts'
 import { adfToMarkdown, markdownToAdf } from '../../index.ts'
 import { largestNesting } from '../../nesting.ts'
+import { toEditorNormal } from '../../adf/editor-normal.ts'
 
 function document(...content: AdfNode[]): AdfDocument {
   return { content, type: 'doc', version: 1 }
@@ -353,7 +354,9 @@ test('refuses marks and attributes nested deeper than the emitter carries', () =
   const roundTrips = (node: AdfNode): void => {
     const spelled = adfToMarkdown(document(node))
     assert.ok(spelled.ok, spelled.ok ? '' : spelled.error.message)
-    assert.deepEqual(markdownToAdf(spelled.value), { ok: true, value: document(node) })
+    const read = markdownToAdf(spelled.value)
+    assert.ok(read.ok, read.ok ? '' : read.error.message)
+    assert.deepEqual(toEditorNormal(read.value), document(node))
   }
 
   assert.equal(markdown(adfToMarkdown(document(paragraph({ marks: [{ attrs, type: 'em' }], text: 'x', type: 'text' })))), deeper('depth', 'em', largestNesting - 3))

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

@@ -1,6 +1,6 @@
 import type { AdfDocument, AdfNode } from '../../adf/document.ts'
 import type { BlockDirective } from '../../adf/block-directives.ts'
-import { adfDocumentFault, carriesOnly } from '../../adf/document.ts'
+import { adfDocumentFault, carriesOnly, nodeAttrs, nodeContent, nodeMarks } from '../../adf/document.ts'
 import { blockDirective } from '../../adf/block-directives.ts'
 import { carriedBlock } from '../opaque-carry.ts'
 import { emitInlineLine } from './inline-line.ts'
@@ -26,7 +26,7 @@ export function adfToMarkdown(document: AdfDocument): Result<string> {
   const fault = adfDocumentFault(document)
   if (fault !== undefined) return faulted(fault, [])
   if (document.version !== 1) return failure('unsupported-document-version', `no markdown spelling carries ADF version ${document.version}`, [])
-  const blocks = emitBlocks(document.content ?? [], 'document', [], 0)
+  const blocks = emitBlocks(nodeContent(document), 'document', [], 0)
   if (!blocks.ok) return blocks
   return success(blocks.value.text === '' ? '' : `${blocks.value.text}\n`)
 }
@@ -63,8 +63,8 @@ function separationBetween(previous: PlacedBlock, next: PlacedBlock, container:
 }
 
 function interruptsParagraph(node: AdfNode): boolean {
-  const items = node.content ?? []
-  const empty = (items[0]?.content ?? []).length === 0
+  const items = nodeContent(node)
+  const empty = items[0] === undefined || nodeContent(items[0]).length === 0
   if (node.type !== 'orderedList') return markerInterruptsParagraph(undefined, empty)
   return markerInterruptsParagraph(listStart(node, items.length) ?? 0, empty)
 }
@@ -110,7 +110,7 @@ function commonMarkText(text: string): EmittedBlock {
 
 function emitDirectiveBlock(node: AdfNode, directive: BlockDirective, path: ConvertErrorPath, depth: number): Result<EmittedBlock> {
   if (node.text !== undefined) return failure('unsupported-node-shape', `a ${node.type} carries no text: this one holds text`, path)
-  const content = node.content ?? []
+  const content = nodeContent(node)
   if (directive.contentModel === 'none' && content.length > 0) return failure('unsupported-node-shape', `a ${node.type} holds no content: this one holds some`, path)
   if (directive.contentModel === 'code') return emitCodeDirective(node, directive, path, depth)
   const header = spellDirectiveHeader(node, directive)
@@ -134,7 +134,7 @@ function emitInlineBody(content: readonly AdfNode[], path: ConvertErrorPath): Re
 
 function emitBlockquote(node: AdfNode, path: ConvertErrorPath, depth: number): Result<EmittedBlock> | undefined {
   if (!carriesOnly(node, [])) return undefined
-  const inner = emitBlocks(node.content ?? [], 'document', path, depth + 1)
+  const inner = emitBlocks(nodeContent(node), 'document', path, depth + 1)
   if (!inner.ok) return inner
   const text = inner.value.text
     .split('\n')
@@ -145,7 +145,7 @@ function emitBlockquote(node: AdfNode, path: ConvertErrorPath, depth: number): R
 
 function emitCodeBlock(node: AdfNode, path: ConvertErrorPath): Result<EmittedBlock> | undefined {
   if (!carriesOnly(node, ['language'])) return undefined
-  const slot = languageSlot(node.attrs?.['language'])
+  const slot = languageSlot(nodeAttrs(node)['language'])
   if (slot.kind === 'attribute') return undefined
   const text = codeBlockText(node, path)
   if (!text.ok) return text
@@ -153,7 +153,7 @@ function emitCodeBlock(node: AdfNode, path: ConvertErrorPath): Result<EmittedBlo
 }
 
 function emitCodeDirective(node: AdfNode, directive: BlockDirective, path: ConvertErrorPath, depth: number): Result<EmittedBlock> {
-  const slot = languageSlot(node.attrs?.['language'])
+  const slot = languageSlot(nodeAttrs(node)['language'])
   const header = spellDirectiveHeader(node, directive, slot.kind === 'attribute' ? [] : ['language'])
   if (header === undefined) return commonMarkLine(carriedBlock(node, path, depth))
   const text = codeBlockText(node, path)
@@ -164,15 +164,15 @@ function emitCodeDirective(node: AdfNode, directive: BlockDirective, path: Conve
 
 function codeBlockText(node: AdfNode, path: ConvertErrorPath): Result<string> {
   let text = ''
-  for (const [index, child] of (node.content ?? []).entries()) {
+  for (const [index, child] of nodeContent(node).entries()) {
     const childPath = [...path, 'content', index]
     if (
       child.type !== 'text' ||
       typeof child.text !== 'string' ||
       child.text === '' ||
-      (child.content ?? []).length > 0 ||
-      (child.marks ?? []).length > 0 ||
-      Object.keys(child.attrs ?? {}).length > 0
+      nodeContent(child).length > 0 ||
+      nodeMarks(child).length > 0 ||
+      Object.keys(nodeAttrs(child)).length > 0
     ) {
       return failure('unsupported-node-shape', `a codeBlock holds plain text nodes only: this ${child.type} node is not one`, childPath)
     }
@@ -185,10 +185,10 @@ function codeBlockText(node: AdfNode, path: ConvertErrorPath): Result<string> {
 
 function emitHeading(node: AdfNode, path: ConvertErrorPath): Result<EmittedBlock> | undefined {
   if (!carriesOnly(node, ['level'])) return undefined
-  const level = node.attrs?.['level']
+  const level = nodeAttrs(node)['level']
   if (typeof level !== 'number' || !Number.isInteger(level) || level < 1 || level > 6) return undefined
   const hashes = '#'.repeat(level)
-  const content = node.content ?? []
+  const content = nodeContent(node)
   if (content.length === 0) return success(commonMarkText(hashes))
   const line = emitInlineLine(content, 'heading', path)
   if (!line.ok) return line
@@ -198,7 +198,7 @@ function emitHeading(node: AdfNode, path: ConvertErrorPath): Result<EmittedBlock
 function emitList(node: AdfNode, path: ConvertErrorPath, depth: number): Result<EmittedBlock> | undefined {
   const ordered = node.type === 'orderedList'
   if (!carriesOnly(node, ordered ? ['order'] : [])) return undefined
-  const items = node.content ?? []
+  const items = nodeContent(node)
   const start = listStart(node, items.length)
   if (start === undefined || items.length === 0) return undefined
   if (items.some((item) => item.type !== 'listItem' || !carriesOnly(item, []))) return undefined
@@ -216,13 +216,13 @@ function emitList(node: AdfNode, path: ConvertErrorPath, depth: number): Result<
 
 function listStart(node: AdfNode, items: number): number | undefined {
   if (node.type !== 'orderedList') return 0
-  const start = node.attrs?.['order']
+  const start = nodeAttrs(node)['order']
   if (typeof start !== 'number' || !Number.isInteger(start) || start < 0 || start > largestListMarker) return undefined
   return start + items - 1 > largestListMarker ? undefined : start
 }
 
 function emitListItem(item: AdfNode, marker: string, path: ConvertErrorPath, depth: number): Result<EmittedBody> | undefined {
-  const inner = emitBlocks(item.content ?? [], 'list-item', path, depth + 1)
+  const inner = emitBlocks(nodeContent(item), 'list-item', path, depth + 1)
   if (!inner.ok) return inner
   if (inner.value.text === '') return success({ fenceColons: 0, text: marker.trimEnd() })
   const indent = ' '.repeat(marker.length)
@@ -232,7 +232,7 @@ function emitListItem(item: AdfNode, marker: string, path: ConvertErrorPath, dep
 }
 
 function emitParagraph(node: AdfNode, path: ConvertErrorPath): Result<EmittedBlock> | undefined {
-  const content = node.content ?? []
+  const content = nodeContent(node)
   if (content.length === 0 || !carriesOnly(node, [])) return undefined
   const line = emitInlineLine(content, 'paragraph', path)
   if (!line.ok) return line
@@ -240,6 +240,6 @@ function emitParagraph(node: AdfNode, path: ConvertErrorPath): Result<EmittedBlo
 }
 
 function emitRule(node: AdfNode): Result<EmittedBlock> | undefined {
-  if (!carriesOnly(node, []) || (node.content ?? []).length > 0) return undefined
+  if (!carriesOnly(node, []) || nodeContent(node).length > 0) return undefined
   return success(commonMarkText('---'))
 }

src/markdown/emit/block-directive-spelling.ts

@@ -3,6 +3,7 @@ import type { BlockDirective } from '../../adf/block-directives.ts'
 import { blockArgument } from '../block-directive-arguments.ts'
 import { isBareToken, spellAttributes, spellJsonAttribute, spellVocabulary } from '../directive-syntax.ts'
 import { markValues, marksAttribute } from '../block-directive-marks.ts'
+import { nodeAttrs, nodeMarks } from '../../adf/document.ts'
 import { vocabularyPairs } from '../../adf/attribute-vocabulary.ts'
 
 export function spellDirectiveHeader(node: AdfNode, directive: BlockDirective, spelledByBody: readonly string[] = []): string | undefined {
@@ -10,17 +11,17 @@ export function spellDirectiveHeader(node: AdfNode, directive: BlockDirective, s
   const argument = spellArgument(node, argumentAttribute)
   if (argument === undefined) return undefined
   const spelled = argumentAttribute === undefined ? spelledByBody : [argumentAttribute, ...spelledByBody]
-  const pairs = vocabularyPairs(node.attrs ?? {}, directive.attributes, spelled)
+  const pairs = vocabularyPairs(nodeAttrs(node), directive.attributes, spelled)
   if (pairs === undefined) return undefined
   const spelledPairs = spellVocabulary(pairs)
-  const marks = node.marks ?? []
+  const marks = nodeMarks(node)
   if (marks.length > 0) spelledPairs.push([marksAttribute, spellJsonAttribute(markValues(marks))])
   const attributes = spellAttributes(spelledPairs)
   return `${node.type}${argument}${attributes === '' ? '' : ` ${attributes}`}`
 }
 
 function spellArgument(node: AdfNode, argumentAttribute: string | undefined): string | undefined {
-  const value = argumentAttribute === undefined ? undefined : node.attrs?.[argumentAttribute]
+  const value = argumentAttribute === undefined ? undefined : nodeAttrs(node)[argumentAttribute]
   if (value === undefined) return ''
   if (typeof value !== 'string' || !isBareToken(value)) return undefined
   return ` ${value}`

src/markdown/emit/image.ts

@@ -1,5 +1,5 @@
 import type { AdfNode } from '../../adf/document.ts'
-import { carriesOnly } from '../../adf/document.ts'
+import { carriesOnly, nodeAttrs, nodeContent } from '../../adf/document.ts'
 import type { ConvertErrorPath } from '../../result.ts'
 import { serializeCanonicalJson } from '../../canonical-json.ts'
 import { tryImageLine } from './inline-line.ts'
@@ -14,11 +14,11 @@ export function tryImage(node: AdfNode, path: ConvertErrorPath): string | undefi
 }
 
 function imageShape(node: AdfNode): { alt: string | undefined; url: string } | undefined {
-  const content = node.content ?? []
+  const content = nodeContent(node)
   const media = content[0]
-  if (!carriesOnly(node, ['layout']) || serializeCanonicalJson(node.attrs ?? {}, 'compact') !== centeredMediaSingle) return undefined
-  if (media === undefined || content.length !== 1 || media.type !== 'media' || !carriesOnly(media, imageAttributes) || (media.content ?? []).length > 0) return undefined
-  const attrs = media.attrs ?? {}
+  if (!carriesOnly(node, ['layout']) || serializeCanonicalJson(nodeAttrs(node), 'compact') !== centeredMediaSingle) return undefined
+  if (media === undefined || content.length !== 1 || media.type !== 'media' || !carriesOnly(media, imageAttributes) || nodeContent(media).length > 0) return undefined
+  const attrs = nodeAttrs(media)
   const alt = attrs['alt']
   const url = attrs['url']
   if (attrs['type'] !== 'external' || typeof url !== 'string') return undefined

src/markdown/emit/inline-directive-spelling.ts

@@ -1,9 +1,10 @@
 import type { AdfNode } from '../../adf/document.ts'
 import type { InlineDirective } from '../../adf/inline-directives.ts'
+import { nodeAttrs } from '../../adf/document.ts'
 import { spellAttributes, spellVocabulary } from '../directive-syntax.ts'
 import { vocabularyPairs } from '../../adf/attribute-vocabulary.ts'
 
 export function spellInlineNodeAttributes(node: AdfNode, directive: InlineDirective): string | undefined {
-  const pairs = vocabularyPairs(node.attrs ?? {}, directive.attributes, directive.textAttribute === undefined ? [] : [directive.textAttribute])
+  const pairs = vocabularyPairs(nodeAttrs(node), directive.attributes, directive.textAttribute === undefined ? [] : [directive.textAttribute])
   return pairs === undefined ? undefined : spellAttributes(spellVocabulary(pairs))
 }

src/markdown/emit/inline-line.ts

@@ -9,6 +9,7 @@ import { inlineDirective } from '../../adf/inline-directives.ts'
 import { largestNesting } from '../../nesting.ts'
 import { longestBacktickRun } from '../backtick-runs.ts'
 import { markSpelling, spellMarkAttributes } from '../mark-spellings.ts'
+import { nodeAttrs, nodeContent, nodeMarks } from '../../adf/document.ts'
 import { sameMark } from '../../adf/editor-normal.ts'
 import { slotLineEndingFault, spellLeafDirective } from '../directive-syntax.ts'
 import { spellDestination, spellTitle } from '../link-syntax.ts'
@@ -127,7 +128,7 @@ function syntax(text: string): InlineSegment {
 }
 
 function refuseContentAndText(node: AdfNode, path: ConvertErrorPath): Result<null> {
-  const holdsContent = (node.content ?? []).length > 0
+  const holdsContent = nodeContent(node).length > 0
   if (holdsContent || node.text !== undefined) {
     const held = holdsContent ? 'content' : 'text'
     return failure('unsupported-node-shape', `a ${node.type} node holds neither content nor text: this one holds ${held}`, path)
@@ -156,7 +157,7 @@ function inlineRuns(nodes: readonly AdfNode[], depth: number, firstIndex: number
   for (const [offset, node] of nodes.entries()) {
     const index = firstIndex + offset
     // spec/flavour.md, Marks.
-    const mark = carries(node, carried, index) ? undefined : (node.marks ?? [])[depth]
+    const mark = carries(node, carried, index) ? undefined : nodeMarks(node)[depth]
     if (mark === undefined) {
       runs.push({ index, kind: 'plain', node })
       continue
@@ -184,7 +185,7 @@ function emitLeaf(node: AdfNode, context: InlineContext, index: number): Result<
     if (!carried.ok) return carried
     return success({ segments: [syntax(carried.value)] })
   }
-  const types = (node.marks ?? []).map((mark) => mark.type)
+  const types = nodeMarks(node).map((mark) => mark.type)
   if (new Set(types).size !== types.length) return failure('unsupported-node-shape', `a ${node.type} node carries one mark type twice`, path)
   const directive = inlineDirective(node.type)
   if (directive === undefined) return emitText(node, context, index, path)
@@ -206,7 +207,7 @@ function emitInlineDirective(node: AdfNode, directive: InlineDirective, index: n
   if (!empty.ok) return empty
   const attributes = spellInlineNodeAttributes(node, directive)
   if (attributes === undefined) return success({ carry: { first: index, last: index } })
-  const slot = directive.textAttribute === undefined ? undefined : node.attrs?.[directive.textAttribute]
+  const slot = directive.textAttribute === undefined ? undefined : nodeAttrs(node)[directive.textAttribute]
   if (slot === undefined) return success({ segments: [syntax(spellLeafDirective(node.type, attributes))] })
   if (typeof slot !== 'string') return success({ carry: { first: index, last: index } })
   const spans = slotLineEndingFault(node.type, slot)
@@ -217,9 +218,9 @@ function emitInlineDirective(node: AdfNode, directive: InlineDirective, index: n
 }
 
 function emitText(node: AdfNode, context: InlineContext, index: number, path: ConvertErrorPath): Result<Emission> {
-  if (Object.keys(node.attrs ?? {}).length > 0) return success({ carry: { first: index, last: index } })
+  if (Object.keys(nodeAttrs(node)).length > 0) return success({ carry: { first: index, last: index } })
   if (typeof node.text !== 'string' || node.text === '') return failure('unsupported-node-shape', 'a text node holds text: this one has none', path)
-  if ((node.content ?? []).length > 0) return failure('unsupported-node-shape', 'a text node holds no content: this one holds some', path)
+  if (nodeContent(node).length > 0) return failure('unsupported-node-shape', 'a text node holds no content: this one holds some', path)
   if (/\r/.test(node.text)) return failure('unspellable-character', 'a text node holds a carriage return CommonMark rewrites', path)
   if (holdsNullCharacter(node.text)) return failure('unspellable-character', 'a text node holds a null character CommonMark replaces', path)
   const escaping: InlineEscaping = context.bracketed ? 'bracketed' : 'backslash'
@@ -260,9 +261,9 @@ function emitEmphasis(nodes: readonly AdfNode[], spelling: string, depth: number
 function emitCodeSpan(nodes: readonly AdfNode[], depth: number, range: NodeRange, path: ConvertErrorPath): Result<Emission> {
   let text = ''
   for (const node of nodes) {
-    if (node.type !== 'text' || (node.marks ?? []).length !== depth + 1) return success({ carry: range })
+    if (node.type !== 'text' || nodeMarks(node).length !== depth + 1) return success({ carry: range })
     if (typeof node.text !== 'string' || node.text === '') return failure('unsupported-node-shape', 'a text node holds text: this one has none', path)
-    if ((node.content ?? []).length > 0) return failure('unsupported-node-shape', 'a text node holds no content: this one holds some', path)
+    if (nodeContent(node).length > 0) return failure('unsupported-node-shape', 'a text node holds no content: this one holds some', path)
     text += node.text
   }
   if (/[\n\r]/.test(text)) return success({ carry: range })
@@ -278,11 +279,11 @@ function needsPadding(text: string): boolean {
 }
 
 function emitLink(nodes: readonly AdfNode[], mark: AdfMark, depth: number, range: NodeRange, context: InlineContext, path: ConvertErrorPath): Result<Emission> {
-  const href = mark.attrs?.['href']
-  const title = mark.attrs?.['title']
+  const href = nodeAttrs(mark)['href']
+  const title = nodeAttrs(mark)['title']
   if (typeof href !== 'string') return success({ carry: range })
   const node = nodes[0]
-  const bare = nodes.length === 1 && node !== undefined && node.type === 'text' && node.text === href && (node.marks ?? []).length === depth + 1
+  const bare = nodes.length === 1 && node !== undefined && node.type === 'text' && node.text === href && nodeMarks(node).length === depth + 1
   if (bare && title === undefined && isAutolink(href) && !holdsEntityReference(href)) return success({ segments: [syntax(`<${href}>`)] })
   const destination = spellDestination(href, path)
   if (!destination.ok) return destination

src/markdown/emit/pipe-table.ts

@@ -1,5 +1,5 @@
 import type { AdfNode } from '../../adf/document.ts'
-import { carriesOnly } from '../../adf/document.ts'
+import { carriesOnly, nodeContent } from '../../adf/document.ts'
 import { spellPipeDelimiter, spellPipeRow } from '../pipe-table-syntax.ts'
 import { tryPipeCell } from './inline-line.ts'
 import type { ConvertErrorPath } from '../../result.ts'
@@ -11,7 +11,7 @@ export function tryPipeTable(node: AdfNode, path: ConvertErrorPath): string | un
   for (const [rowIndex, row] of rows.entries()) {
     const cells: string[] = []
     for (const [cellIndex, paragraph] of row.entries()) {
-      const content = paragraph.content ?? []
+      const content = nodeContent(paragraph)
       const line = content.length === 0 ? '' : tryPipeCell(content, [...path, 'content', rowIndex, 'content', cellIndex, 'content', 0])
       if (line === undefined) return undefined
       cells.push(line)
@@ -23,12 +23,12 @@ export function tryPipeTable(node: AdfNode, path: ConvertErrorPath): string | un
 }
 
 function pipeRows(node: AdfNode): AdfNode[][] | undefined {
-  const rows = node.content ?? []
-  const columns = (rows[0]?.content ?? []).length
+  const rows = nodeContent(node)
+  const columns = rows[0] === undefined ? 0 : nodeContent(rows[0]).length
   if (!carriesOnly(node, []) || columns === 0) return undefined
   const grid: AdfNode[][] = []
   for (const [index, row] of rows.entries()) {
-    const cells = row.content ?? []
+    const cells = nodeContent(row)
     if (row.type !== 'tableRow' || !carriesOnly(row, []) || cells.length !== columns) return undefined
     const wanted = index === 0 ? 'tableHeader' : 'tableCell'
     const paragraphs: AdfNode[] = []
@@ -43,7 +43,7 @@ function pipeRows(node: AdfNode): AdfNode[][] | undefined {
 }
 
 function plainParagraph(cell: AdfNode): AdfNode | undefined {
-  const content = cell.content ?? []
+  const content = nodeContent(cell)
   const paragraph = content[0]
   if (paragraph === undefined || content.length !== 1 || paragraph.type !== 'paragraph' || !carriesOnly(paragraph, [])) return undefined
   return paragraph

src/markdown/mark-spellings.ts

@@ -2,6 +2,7 @@ import type { AdfMark } from '../adf/document.ts'
 import type { AttributeVocabulary } from '../adf/attribute-vocabulary.ts'
 import type { MarkType } from '../adf/mark-attributes.ts'
 import { isMarkType, markAttributes } from '../adf/mark-attributes.ts'
+import { nodeAttrs } from '../adf/document.ts'
 import { spellAttributes, spellVocabulary } from './directive-syntax.ts'
 import { vocabularyPairs } from '../adf/attribute-vocabulary.ts'
 
@@ -30,6 +31,6 @@ export function markSpelling(type: string): MarkSpelling | undefined {
 }
 
 export function spellMarkAttributes(mark: AdfMark, vocabulary: AttributeVocabulary): string | undefined {
-  const pairs = vocabularyPairs(mark.attrs ?? {}, vocabulary, [])
+  const pairs = vocabularyPairs(nodeAttrs(mark), vocabulary, [])
   return pairs === undefined ? undefined : spellAttributes(spellVocabulary(pairs))
 }

src/markdown/parse/directive-nodes.ts

@@ -3,7 +3,7 @@ import type { BlockDirective } from '../../adf/block-directives.ts'
 import type { ConvertFault } from '../../result.ts'
 import type { DirectiveAttributes, DirectiveValue } from '../directive-syntax.ts'
 import type { Elsewhere } from './directive-attributes.ts'
-import { attributeNestingMessage } from '../../adf/document.ts'
+import { attributeNestingMessage, nodeMarks } from '../../adf/document.ts'
 import { attributeValue, directiveLineEscape, inlineDirectiveEscape, spellAttributeValue, unknownDirectiveFault } from '../directive-syntax.ts'
 import { blockArgument } from '../block-directive-arguments.ts'
 import { blockDirective } from '../../adf/block-directives.ts'
@@ -89,7 +89,7 @@ function blockSpellingFault(name: string): ConvertFault | undefined {
 function slotText(content: readonly AdfNode[]): string | undefined {
   if (content.length === 0) return ''
   const only = content.length === 1 ? content[0] : undefined
-  if (only?.type !== 'text' || (only.marks ?? []).length > 0 || typeof only.text !== 'string') return undefined
+  if (only?.type !== 'text' || nodeMarks(only).length > 0 || typeof only.text !== 'string') return undefined
   return only.text
 }
 

src/markdown/parse/inline-content.ts

@@ -8,6 +8,7 @@ import { delimiterFlags, matchEmphasis, runLength } from '../emphasis-matching.t
 import { failure, faulted, success, type ConvertErrorPath, type Result } from '../../result.ts'
 import { inlineDirective } from '../../adf/inline-directives.ts'
 import { mergeAdjacentText } from '../../adf/editor-normal.ts'
+import { nodeAttrs, nodeMarks } from '../../adf/document.ts'
 import { normalizeLabel, readInlineTarget, readLabel } from '../link-syntax.ts'
 import { readCarriedInline } from '../opaque-carry.ts'
 import { readDirectiveMark } from './directive-marks.ts'
@@ -337,7 +338,7 @@ function imageAlt(inner: readonly Piece[], path: ConvertErrorPath): Result<strin
 function altText(node: AdfNode): string {
   if (node.type === 'hardBreak') return ' '
   const slot = inlineDirective(node.type)?.textAttribute
-  const spelled = slot === undefined ? undefined : node.attrs?.[slot]
+  const spelled = slot === undefined ? undefined : nodeAttrs(node)[slot]
   return typeof spelled === 'string' ? spelled : (node.text ?? '')
 }
 
@@ -409,7 +410,7 @@ function markType(character: string, used: number): string {
 // A node cannot carry one mark type twice (AGENTS.md §14).
 function applyMark(nodes: readonly AdfNode[], mark: AdfMark): AdfNode[] {
   return nodes.map((node) => {
-    const marks = node.marks ?? []
+    const marks = nodeMarks(node)
     return marks.some((carried) => carried.type === mark.type) ? node : { ...node, marks: [mark, ...marks] }
   })
 }

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

@@ -9,6 +9,7 @@ import { failure, faulted, positioned, success, type ConvertErrorPath, type Pars
 import { languageSlot } from '../code-language.ts'
 import { largestNesting } from '../../nesting.ts'
 import { listBreakName, listBreakSpelling } from '../list-break.ts'
+import { nodeAttrs } from '../../adf/document.ts'
 import { parseBlocks } from './blocks.ts'
 import { parseInlineContent } from './inline-content.ts'
 import { readBlockDirectiveNode } from './directive-nodes.ts'
@@ -106,7 +107,7 @@ function directiveBody(read: BlockDirectiveNode, blocks: Block[] | undefined, de
 function codeDirectiveNode(node: AdfNode, blocks: readonly Block[], path: ConvertErrorPath): Result<AdfNode> {
   const only = blocks.length === 1 ? blocks[0] : undefined
   if (only?.kind !== 'code') return failure('unsupported-node-shape', `${node.type} takes one code block as its body: this body is not one`, path)
-  const attribute = node.attrs?.['language']
+  const attribute = nodeAttrs(node)['language']
   const fromFence = only.language !== ''
   const slot = languageSlot(fromFence ? only.language : attribute)
   if ((slot.kind === 'fence') !== fromFence || (fromFence && attribute !== undefined)) {