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
+and no attributes merged, JSON number semantics, an empty attrs object, marks array or content
-key — the only domain markdown can restore.
+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.
 
@@ -63,8 +63,11 @@ module, so entity decoding is complete without one. The CommonMark spec suite is
 data and ships vendored at `corpus/commonmark-spec/` rather than as the `commonmark-spec` dev
 dependency — that package is CommonJS-only, and Renovate auto-bumping a spec version would silently
 point the vendored exception list's example numbers at a renumbered suite. A spec bump is a
-deliberate re-pin, exceptions re-derived by hand beside it. `devDependencies`: few, each earning its
+deliberate re-pin, exceptions re-derived by hand beside it. Atlassian's ADF JSON Schemas ship
-keep; they never reach a consumer.
+vendored the same way, at `spec/adf-schema/`, rather than as the `@atlaskit/adf-schema` dev
+dependency — CommonJS-only, some fifty packages with React among them, and a release most days for
+Renovate to automerge — re-pinned by hand when a payload or a report shows the need.
+`devDependencies`: few, each earning its keep; they never reach a consumer.
 
 ## 6. The package contract
 
@@ -220,8 +223,7 @@ functions, and a branch floor that only ever moves upward. It sits below 100 bec
 compared against `undefined` — have a half no valid document reaches.
 
 The corpus, all checked in: hand-built fixtures per node and combination; real sanitized ADF from
-live Atlassian APIs; property-generated ADF trees; the CommonMark spec suite against
+live Atlassian APIs; the CommonMark spec suite against `markdownToAdf` and `markdownToHtml`.
-`markdownToAdf` and `markdownToHtml`.
 
 `spec/flavour.md` is read as a source too, so the node tables cannot drift from the prose they
 copy: each `- ` bullet in `## Block nodes`, `## Inline nodes` and `## Marks` declares the nodes
@@ -231,6 +233,12 @@ of a bullet; fenced examples are skipped. It guards the attributes alone: nodes
 content model share a bullet, and the argument attribute is spelled ahead of `Attributes: `, so
 both answer to the round-trip corpus and to nothing else where a node has no fixture.
 
+The tables answer to Atlassian's schema too (§5): for every node and mark they spell, the attribute
+names and kinds equal what `full.json` and `stage-0.json` hold between them. Value sets stay
+documentation, since any value round-trips. What the schema holds and the tables do not spell is
+pinned by name — an attribute as a gap, a type as carried — so a re-pin adding either goes red until
+someone spells it or pins it.
+
 ## 11. Code rules
 
 - Two-space indent, strict TypeScript, English everywhere. Alphabetical order wherever order

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/adf-schema/LICENSE

@@ -0,0 +1,13 @@
+Copyright 2019 Atlassian Pty Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.

spec/adf-schema/LICENSE-2.0.txt

@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

spec/adf-schema/README.md

@@ -0,0 +1,6 @@
+# Atlassian's ADF JSON Schemas
+
+`full.json` and `stage-0.json` are byte-exact from `dist/json-schema/v1/` in
+[`@atlaskit/adf-schema` 57.4.9](https://registry.npmjs.org/@atlaskit/adf-schema/-/adf-schema-57.4.9.tgz)
+(© Atlassian Pty Ltd, Apache-2.0: `LICENSE` is the package's own notice, `LICENSE-2.0.txt` the
+licence it names).

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 —
+parsing to anything but one unmarked text node — adjacent text nodes with identical marks and no
-is a named error, and so is a `text` key in `{attrs}`. An enclosing mark spelling does not reach
+attributes merged first — is a named error, and so is a `text` key in `{attrs}`. An enclosing mark
-into the slot. The rest take no content, `:text` included; content on a node that takes none is a
+spelling does not reach into the slot. The rest take no content, `:text` included; content on a
-named error.
+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
+the rest plain text; `markdownToAdf` merges adjacent text nodes carrying identical marks and no
-(AGENTS.md §2). Input reads that spelling alone: the value is one run of spaces and tabs, or one
+attributes (AGENTS.md §2). Input reads that spelling alone: the value is one run of spaces and
-run of newlines, and anything else — a mixed run, or text CommonMark carries plainly — is a named
+tabs, or one run of newlines, and anything else — a mixed run, or text CommonMark carries plainly —
-error.
+is a named error.
 
 ```
 :text{text="  "}Two leading spaces held, and one text node split:text{text="\n"}over two lines.

src/adf-schema.test.ts

@@ -0,0 +1,183 @@
+import assert from 'node:assert/strict'
+import { createHash } from 'node:crypto'
+import { readFileSync } from 'node:fs'
+import { dirname, join } from 'node:path'
+import test from 'node:test'
+import { fileURLToPath } from 'node:url'
+
+import type { AttributeKind, AttributeVocabulary } from './adf/attribute-vocabulary.ts'
+import { blockDirectives } from './adf/block-directives.ts'
+import { inlineDirectives } from './adf/inline-directives.ts'
+import { markAttributes } from './adf/mark-attributes.ts'
+import { blockArgument } from './markdown/block-directive-arguments.ts'
+
+type Held = Map<string, Set<AttributeKind>>
+type Properties = Map<string, SchemaObject[]>
+type SchemaObject = Readonly<Record<string, unknown>>
+type Spelled = [string, Map<string, AttributeKind>]
+
+const carried = ['alignment', 'annotation', 'backgroundColor', 'blockCard', 'bodiedRule', 'breakout', 'dataConsumer', 'embedCard', 'fontSize', 'fragment', 'indentation', 'inlineExtension', 'placeholder']
+const definitionReference = '#/definitions/'
+const gaps = ['layoutSection.columnRuleStyle', 'link.collection', 'link.id', 'link.occurrenceKey', 'rule.color', 'rule.style', 'rule.weight']
+const grammarOwn = ['doc', 'text']
+const readKeywords = ['$ref', 'additionalProperties', 'allOf', 'anyOf', 'enum', 'items', 'maxItems', 'maximum', 'minItems', 'minLength', 'minimum', 'pattern', 'properties', 'required', 'type']
+const root = join(dirname(fileURLToPath(import.meta.url)), '..', 'spec', 'adf-schema')
+const schemaFiles = ['full.json', 'stage-0.json']
+
+test('the ADF JSON Schemas are @atlaskit/adf-schema 57.4.9, vendored byte-exact', () => {
+  const digest = (name: string) => createHash('sha256').update(readFileSync(join(root, name))).digest('hex')
+  assert.equal(digest('full.json'), '75f080928a970250eb8289e9cae5374e3c2a6c0ac3ca22478acaa9d3f39484a3')
+  assert.equal(digest('stage-0.json'), '56747e5a71c0d5f8c58f94180d69e4482f62c08020d66aaf327333681fcc1c8f')
+})
+
+test('the tables spell the attribute names and kinds the ADF JSON Schemas give each type they spell, the pinned gaps apart', () => {
+  const held = schemaTypes()
+  const spelledTypes = spelled()
+  const found: string[] = []
+  const gapsHeld = new Set<string>()
+  for (const [type, spelledKinds] of spelledTypes) {
+    const kinds = held.get(type)
+    if (kinds === undefined) {
+      found.push(`${type}: the tables spell the type, the schema holds no definition of it`)
+      continue
+    }
+    for (const [attribute, schemaKinds] of kinds) {
+      const kind = spelledKinds.get(attribute)
+      const holds = [...schemaKinds].sort().join(' or ')
+      if (kind === undefined && gaps.includes(`${type}.${attribute}`)) gapsHeld.add(`${type}.${attribute}`)
+      else if (kind === undefined) found.push(`${type}.${attribute}: the schema holds ${holds}, the tables spell nothing and the gaps list does not name it`)
+      else if (schemaKinds.size !== 1 || !schemaKinds.has(kind)) found.push(`${type}.${attribute}: the tables spell ${kind}, the schema holds ${holds}`)
+    }
+    for (const [attribute, kind] of spelledKinds) if (!kinds.has(attribute)) found.push(`${type}.${attribute}: the tables spell ${kind}, the schema holds nothing`)
+  }
+  for (const gap of gaps) {
+    if (gapsHeld.has(gap)) continue
+    const [type = '', attribute = ''] = gap.split('.')
+    const spelledKinds = spelledTypes.find(([name]) => name === type)?.[1]
+    const kind = spelledKinds?.get(attribute)
+    if (spelledKinds === undefined) found.push(`${gap}: the gaps list names it, the tables spell no ${type} type`)
+    else if (kind === undefined) found.push(`${gap}: the gaps list names it, the schema holds nothing`)
+    else found.push(`${gap}: the gaps list names it, the tables spell ${kind}`)
+  }
+  assert.deepEqual(found, [])
+})
+
+test("the ADF JSON Schemas hold no type the tables leave unspelled, the pinned carried ones and the grammar's own apart", () => {
+  const held = schemaTypes()
+  const spelledNames = new Set(spelled().map(([type]) => type))
+  const found: string[] = []
+  for (const type of held.keys()) {
+    if (!spelledNames.has(type) && !carried.includes(type) && !grammarOwn.includes(type)) found.push(`${type}: the schema holds the type, the tables spell none of it and the carried list does not name it`)
+  }
+  for (const type of carried) {
+    if (!held.has(type)) found.push(`${type}: the carried list names the type, the schema holds no definition of it`)
+    if (spelledNames.has(type)) found.push(`${type}: the carried list names the type, and the tables spell it`)
+  }
+  assert.deepEqual(found, [])
+})
+
+function spelled(): Spelled[] {
+  return [
+    ...Object.entries(blockDirectives).map(([type, entry]) => spelledType(type, entry.attributes, blockArgument(type))),
+    ...Object.entries(inlineDirectives).map(([type, entry]) => spelledType(type, entry.attributes)),
+    ...Object.entries(markAttributes).map(([type, attributes]) => spelledType(type, attributes)),
+  ]
+}
+
+function spelledType(type: string, attributes: AttributeVocabulary, argument?: string): Spelled {
+  const kinds = new Map(Object.entries(attributes))
+  if (argument !== undefined) kinds.set(argument, 'string')
+  return [type, kinds]
+}
+
+function schemaTypes(): Map<string, Held> {
+  const held = new Map<string, Held>()
+  for (const file of schemaFiles) {
+    const definitions = schemaObject(schemaObject(JSON.parse(readFileSync(join(root, file), 'utf8')), file)['definitions'], `${file} definitions`)
+    for (const [name, definition] of Object.entries(definitions)) {
+      const where = `${file} ${name}`
+      for (const properties of alternatives(schemaObject(definition, where), definitions, where)) {
+        const attributes = (properties.get('attrs') ?? []).flatMap((attrs) => alternatives(attrs, definitions, `${where} attrs`)).flatMap((alternative) => [...alternative])
+        for (const type of (properties.get('type') ?? []).flatMap((schema) => enumStrings(schema, `${where} type`))) {
+          const kinds = held.get(type) ?? new Map<string, Set<AttributeKind>>()
+          held.set(type, kinds)
+          for (const [attribute, schemas] of attributes) {
+            const attributeKinds = kinds.get(attribute) ?? new Set<AttributeKind>()
+            kinds.set(attribute, attributeKinds)
+            for (const schema of schemas) for (const kind of propertyKinds(schema, `${where} ${type}.${attribute}`)) attributeKinds.add(kind)
+          }
+        }
+      }
+    }
+  }
+  return held
+}
+
+function alternatives(schema: SchemaObject, definitions: SchemaObject, where: string): Properties[] {
+  const own = Object.entries(schemaObject(readSchema(schema, where)['properties'] ?? {}, `${where} properties`))
+  let found: Properties[] = [new Map(own.map(([name, property]): [string, SchemaObject[]] => [name, [readSchema(schemaObject(property, `${where} ${name}`), `${where} ${name}`)]]))]
+  if (schema['$ref'] !== undefined) found = intersect(found, alternatives(referenced(schema['$ref'], definitions, where), definitions, `${where} ${String(schema['$ref'])}`))
+  for (const branch of branches(schema['allOf'], `${where} allOf`)) found = intersect(found, alternatives(branch, definitions, `${where} allOf`))
+  if (schema['anyOf'] !== undefined) found = intersect(found, branches(schema['anyOf'], `${where} anyOf`).flatMap((branch) => alternatives(branch, definitions, `${where} anyOf`)))
+  return found
+}
+
+function readSchema(schema: SchemaObject, where: string): SchemaObject {
+  const unread = Object.keys(schema).find((keyword) => !readKeywords.includes(keyword))
+  if (unread !== undefined) return assert.fail(`${where}: the schema holds the keyword ${unread}, which the gate does not read`)
+  const extra = schema['additionalProperties']
+  return extra === undefined || typeof extra === 'boolean' ? schema : assert.fail(`${where}: additionalProperties holds a schema, which the gate does not read`)
+}
+
+function intersect(left: readonly Properties[], right: readonly Properties[]): Properties[] {
+  return left.flatMap((own) =>
+    right.map((other) => {
+      const merged = new Map(own)
+      for (const [name, schemas] of other) merged.set(name, [...(merged.get(name) ?? []), ...schemas])
+      return merged
+    }),
+  )
+}
+
+function referenced(reference: unknown, definitions: SchemaObject, where: string): SchemaObject {
+  const name = typeof reference === 'string' && reference.startsWith(definitionReference) ? reference.slice(definitionReference.length) : undefined
+  return schemaObject(name === undefined ? undefined : definitions[name], `${where}: the reference ${String(reference)}`)
+}
+
+function branches(value: unknown, where: string): SchemaObject[] {
+  if (value === undefined) return []
+  return Array.isArray(value) ? value.map((branch, index) => schemaObject(branch, `${where} ${index}`)) : assert.fail(`${where} is no array of schemas`)
+}
+
+function enumStrings(schema: SchemaObject, where: string): string[] {
+  const values = schema['enum']
+  return Array.isArray(values) ? values.filter((value: unknown): value is string => typeof value === 'string') : assert.fail(`${where}: the type property holds no enum naming the type`)
+}
+
+function propertyKinds(property: SchemaObject, where: string): AttributeKind[] {
+  const type = property['type']
+  if (type === 'boolean') return ['boolean']
+  if (type === 'integer' || type === 'number') return ['number']
+  if (type === 'string') return ['string']
+  if (type === 'array' || type === 'object') return ['json']
+  if (type !== undefined) return assert.fail(`${where}: the schema types it ${JSON.stringify(type)}, which reads as no attribute kind`)
+  const combinator = ['$ref', 'allOf', 'anyOf'].find((keyword) => property[keyword] !== undefined)
+  if (combinator !== undefined) return assert.fail(`${where}: the schema holds the keyword ${combinator}, which the gate reads as no attribute kind`)
+  const values = property['enum']
+  return Array.isArray(values) ? values.map(valueKind) : ['json']
+}
+
+function valueKind(value: unknown): AttributeKind {
+  if (typeof value === 'boolean') return 'boolean'
+  if (typeof value === 'number') return 'number'
+  if (typeof value === 'string') return 'string'
+  return 'json'
+}
+
+function schemaObject(value: unknown, where: string): SchemaObject {
+  return isSchemaObject(value) ? value : assert.fail(`${where} is no JSON Schema object`)
+}
+
+function isSchemaObject(value: unknown): value is SchemaObject {
+  return typeof value === 'object' && value !== null && !Array.isArray(value)
+}

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
+  if (nodeMarks(node).length > 0 || node.text !== undefined) return false
-  return holdsOnly(node.attrs ?? {}, attributes)
+  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 {
+function marksFault(marks: readonly AdfMark[]): ConvertFault | undefined {
-  for (const mark of marks ?? []) {
+  for (const mark of marks) {
-    const fault = attributesFault(mark.attrs, mark.type, markAttributeNesting)
+    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 {
+function attributesFault(attrs: AdfAttributes, type: string, levels: number = largestNesting): ConvertFault | undefined {
-  for (const [key, value] of Object.entries(attrs ?? {})) {
+  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 {
+function objectMembers(value: { [key: string]: JsonValue }, indent: string): Member[] {
-  if (Array.isArray(value)) {
-    if (value.length === 0) return '[]'
-    const items = value.map((item) => serialize(item, indent, depth + 1))
-    return `[${join(items, indent, depth)}]`
-  }
-  if (value !== null && typeof value === 'object') {
-    const keys = Object.keys(value).sort()
-    if (keys.length === 0) return '{}'
   const separator = indent === '' ? ':' : ': '
-    const entries = keys.map((key) => `${JSON.stringify(key)}${separator}${serialize(value[key] ?? null, indent, depth + 1)}`)
+  return Object.keys(value)
-    return `{${join(entries, indent, depth)}}`
+    .sort()
-  }
+    .map((key) => ({ label: `${JSON.stringify(key)}${separator}`, value: value[key] ?? null }))
-  return JSON.stringify(value)
 }
 
-function join(parts: readonly string[], indent: string, depth: number): string {
+function schedule(pending: Pending[], open: string, members: readonly Member[], close: string, indent: string, depth: number): void {
-  if (indent === '') return parts.join(',')
+  if (members.length === 0) {
-  const inner = `\n${indent.repeat(depth + 1)}`
+    pending.push(`${open}${close}`)
-  return `${inner}${parts.join(`,${inner}`)}\n${indent.repeat(depth)}`
+    return
+  }
+  const inner = indent === '' ? '' : `\n${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 items = nodeContent(node)
-  const empty = (items[0]?.content ?? []).length === 0
+  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 ||
+      nodeContent(child).length > 0 ||
-      (child.marks ?? []).length > 0 ||
+      nodeMarks(child).length > 0 ||
-      Object.keys(child.attrs ?? {}).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 (!carriesOnly(node, ['layout']) || serializeCanonicalJson(nodeAttrs(node), 'compact') !== centeredMediaSingle) return undefined
-  if (media === undefined || content.length !== 1 || media.type !== 'media' || !carriesOnly(media, imageAttributes) || (media.content ?? []).length > 0) return undefined
+  if (media === undefined || content.length !== 1 || media.type !== 'media' || !carriesOnly(media, imageAttributes) || nodeContent(media).length > 0) return undefined
-  const attrs = media.attrs ?? {}
+  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 href = nodeAttrs(mark)['href']
-  const title = mark.attrs?.['title']
+  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 rows = nodeContent(node)
-  const columns = (rows[0]?.content ?? []).length
+  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)) {

todo-history.md

@@ -562,6 +562,27 @@ The done `todo.md` items in full, as they were written. `todo.md` keeps a one-li
       `instrumentisto/geckodriver`, currency over size — the leg's whole worth is a real
       SpiderMonkey, which decays the moment the pin stops moving, and the smaller image was four
       Firefox majors behind with a publisher that may go quiet while Renovate stays silent.
+- [x] **11 — Atlassian's ADF schema as the tables' truth (`0.2.0`).** `@atlaskit/adf-schema`'s two
+      JSON Schemas vendored rather than the package installed (AGENTS.md §5), and the node tables
+      gated against them (§10). **Settled** (the maintainer, 2026-09-13): vendored at
+      `spec/adf-schema/` and re-pinned by hand when a need shows; the gate compares attribute names
+      and kinds, never value sets, over `full.json` and `stage-0.json` together.
+  - [x] **11a — The vendored schema.** `full.json` and `stage-0.json`, byte-exact from
+        `@atlaskit/adf-schema@57.4.9`'s `dist/json-schema/v1/`, at `spec/adf-schema/`, each pinned
+        by its SHA-256 in a test the way `spec.json` is. The version, the source and the Apache-2.0
+        attribution sit beside them with the licence text; no gate re-serializes either file.
+  - [x] **11b — The gate.** For each node and mark type the tables spell, the attribute names and
+        kinds equal the union over every definition in both files whose `type` enum names it,
+        `anyOf`/`allOf` branches included, the argument slot (`panelType`, `state`) counting as
+        spelled. Kinds: `string`; `number`, `integer` included; `boolean`; `json` for an object, an
+        array or an untyped value; an `enum`-only attribute takes its values' kind. What the schema
+        holds past the tables is pinned in two exact lists — an entry the schema no longer needs is
+        red, like a difference neither list names: gaps, attributes of a spelled type (57.4.9:
+        `link` `collection` `id` `occurrenceKey`, `rule` `color` `style` `weight`, `layoutSection`
+        `columnRuleStyle`), emptied by 13; and carried, types the tables do not spell (`alignment`
+        `annotation` `backgroundColor` `blockCard` `bodiedRule` `breakout` `dataConsumer`
+        `embedCard` `fontSize` `fragment` `indentation` `inlineExtension` `placeholder`), `doc` and
+        `text` counting as the grammar's own.
 
 ## 5 — Ship `0.1.0`
 

todo.md

@@ -5,9 +5,11 @@ milestone. A done item shrinks to its title here; its full text moves to `todo-h
 
 ## Milestones
 
-Shipping order: 3h, 3i, 3j, 5a, 5b, 5c, 5d, 5 → `0.1.0` (shipped 2026-09-05); 5e before 2027-01; 3k, 4, 4b, 4c, 5g, 10, 11, 12 → `0.2.0`; 4d, 5f → `0.2.1`;
+Shipping order: 3h, 3i, 3j, 5a, 5b, 5c, 5d, 5 → `0.1.0` (shipped 2026-09-05); 3k, 11, 4, 12, 13, 4b, 4c, 10, 5g → `0.2.0`; 4d, 5f → `0.2.1`;
-6, 7 → `0.3.0`; 9 → TBD.
+6, 7 → `0.3.0`; 9 → TBD; 5e last.
-The numbering is the order the work was planned in, not the order it ships.
+The numbering is the order the work was planned in, not the order it ships. `0.2.0`'s order is settled
+(the maintainer, 2026-09-13): 11 makes the tables 4 generates from answer to Atlassian's schema, 4
+proves 12, 13 spells 11's gaps in 12's grammar, and 12 rewrites code 4b and 4c change.
 
 - [x] **0 — Scaffold.**
 - [x] **1a — The directive grammar.**
@@ -42,19 +44,37 @@ The numbering is the order the work was planned in, not the order it ships.
   - [x] **3j — The carry and the combinations.**
   - [x] **3k — The CommonMark spec suite.**
 - [ ] **4 — Round-trip property tests (`0.2.0`)**, widening 3j's corpus round-trip past the
-      documents a human wrote — the thing that proves 2 and 3 beyond them. Editor-normal (§2) is
+      documents a human wrote — the thing that proves 2 and 3 beyond them.
-      finished here, on 3i's merging — `toEditorNormal(doc)` and the equality the round-trip
+      **Settled** (the maintainer, 2026-09-13): `fast-check` generates and shrinks. The gate runs a
-      asserts, which over normalized input is the canonical serializer's compact spelling —
+      fixed seed, the properties together adding about five seconds per engine; an environment
-      rather than staying spelled inline as `?? []` at every reader. The
+      variable raises the runs and randomizes the seed for local digging, and a counterexample
-      reading half is `nodeContent`/`nodeAttrs`/`nodeMarks` over the ~28 sites spelling it
+      found becomes a round-trip fixture. The generators draw from the node tables — each node's
-      inline today, which also lifts the branch floor §10 keeps below 100 for exactly those
+      content model and attribute vocabulary as `adf/` records them, which 11 holds to Atlassian's
-      halves.
+      schema — and misplace a share of nodes so the carry (§3) is exercised; no JSON Schema walker
-      Generators emit editor-normal ADF (§2). Real sanitized ADF from live Atlassian APIs lands
+      enters the tests. `toEditorNormal` stays internal. 2e5's collision test goes, since a
-      here too (§10), in `corpus/real-payloads/`: an ADF→markdown→ADF check with no expected
+      collision already fails the round-trip on the same fixtures; the fixture-duplicate test
-      markdown, the payloads supplied by the maintainer. This subsumes 2e5's collision property —
+      stays.
-      a document that round-trips proves no other document shares its spelling — so decide here
+  - [ ] **4.1 — Editor-normal and the node accessors.** `toEditorNormal(doc)` in
-      whether that gate stays as the parser-free, faster-failing signal or goes; the half holding
+        `src/adf/editor-normal.ts`, on 3i's merging: adjacent text nodes carrying identical marks and
-      no fixture duplicates is hygiene rather than a round-trip claim, and stays either way.
+        no attributes merged, an empty `attrs`, `marks` or `content` the absent key, `-0` read as `0`
+        (§2); the round-trip tests compare the parser's output through it, and `serializeCanonicalJson`
+        beneath it walks iteratively. `nodeContent`/`nodeAttrs`/`nodeMarks` replace the 46 inline
+        `?? []`/`?? {}` reads in `src/` (23 `content`, 12 `marks`, 11 `attrs`) and the `attrs?.[key]`
+        reads, and the branch floor rises to the integer floor of what the suite then measures.
+        **Settled** (the maintainer, 2026-09-14): a text node carrying attributes never merges —
+        `0.1.0` merged a carried one into its neighbour on read-back — and the fix lands here, as does
+        the iterative serializer.
+  - [ ] **4.2 — The ADF property.** `fast-check` joins `devDependencies`, AGENTS.md §5 naming what
+        it earns — shrinking a failing document to the nodes that break it — and §10 the properties
+        beside the corpus. A generated editor-normal document either refuses in `adfToMarkdown`
+        with a `ConvertError` or reads back through `markdownToAdf` to an equal document, and
+        nothing throws, under Node, Deno and Bun alike. 2e5's collision test is deleted.
+  - [ ] **4.3 — The markdown property.** Generated markdown through `markdownToAdf` never throws,
+        and the runs fit the budget; where it parses and `adfToMarkdown` spells the result, that
+        spelling parses and emits to itself byte for byte (§2).
+  - [ ] **4.4 — The real payloads.** `corpus/real-payloads/` holds the maintainer's sanitized
+        payloads, each round-tripped ADF→markdown→ADF with no expected markdown. It waits on the
+        maintainer placing the files.
 - [ ] **4b — The block walk's retry (`0.2.0`).** `emitBlock` walks a subtree twice wherever
       `readableBlock` reads it whole and then gives up — a list item whose first line reads back
       as a thematic break — and the walk below does the same, so the cost doubles per level:
@@ -98,15 +118,18 @@ The numbering is the order the work was planned in, not the order it ships.
       timing is what turns "slow or hung" from a guess into a reading; the browser leg's own
       5.4–7.9s against a 17s warm gate is the number that made it obviously cheap.
 - [x] **5 — Ship `0.1.0`.**
-- [ ] **5e — The publish token's deadline (before 2027-01).** `0.1.0` published only once the npm
+- [ ] **5e — The publish token's deadline.** `0.1.0` published only once the npm
       token carried **Bypass 2FA**: the account requiring no 2FA on writes was not enough, and npm
       answered `EOTP` until the token itself bypassed. npm retires bypass-2FA tokens for direct
-      publishing around January 2027, and its replacement — trusted publishing over OIDC —
+      publishing around January 2027, leaving them `npm stage publish`, which a maintainer
-      supports GitHub Actions, GitLab CI, CircleCI and Buildkite, not Gitea or self-hosted
+      approves with 2FA; its replacement — trusted publishing over OIDC — supports GitHub-hosted
-      runners. So the release path has an expiry date and no drop-in successor yet. Revisit before
+      Actions, GitLab.com's shared runners and CircleCI's cloud, self-hosted runners planned
-      the deadline: whether npm has added Gitea or self-hosted OIDC, and otherwise whether the
+      without a date. So the release path has an expiry date and no drop-in successor yet. Revisit:
-      release moves to a human-approved staged publish — which fits badly with publish-on-merge,
+      whether npm has added Gitea or self-hosted OIDC, and otherwise whether the
+      release moves to the staged publish — which fits badly with publish-on-merge,
       and is the trade to weigh rather than discover on a red release run.
+      **Settled** (the maintainer, 2026-09-13): last of the known work, clear of `0.2.0`, placed
+      there knowing the cutoff may land before `0.2.0` ships.
 - [ ] **5f — Publish the bundle size (`0.2.1`).** Measure the shipped artifact and put the number in the
       README, kept honest by the release pipeline rather than by a human re-reading it. The
       quantity is what a consumer downloads and loads: the tarball `npm pack` produces, its
@@ -120,12 +143,15 @@ The numbering is the order the work was planned in, not the order it ships.
 - [ ] **5g — Reweight the README for the reader (`0.2.0`).** It opens with the pre-launch rationale —
       Atlassian's REST APIs, `pf-editor-service/convert` being decommissioned, a link to
       JRACLOUD-77436 — where a shipped package should answer what it is, what it does and for whom
-      first, then the shortest runnable example; the reader's top seconds go to "why this exists"
+      first, then the shortest runnable example.
-      instead of "what I can do with it". Demote the Jira/endpoint background to a later "why
+      **Settled** (the maintainer, 2026-09-13): the background goes entirely, no endpoint, ticket or
-      losslessness" note or drop it — the internal references (the `jira.atlassian.com` URL,
+      "why" note left. The top follows the package-README order: an npm version badge and the Gitea
-      `pf-editor-service/convert`) don't belong in published text at all, no ticket IDs or internal
+      Actions badge, a tagline that is also `package.json`'s `description`, a feature list and a
-      URLs. The `0.3.0` HTML future should read as an aside, not the lede: the package reads as a
+      one-line table of contents, then install and the shortest runnable example; a table of
-      shipped `0.1.0`, not a work-in-progress.
+      everything exported sits near the bottom. The HTML directions are one aside line under the API
+      until `0.3.0` ships them, the `// 0.3.0` signatures and the `0.3.0` guarantee going until then.
+      The tagline and `description` read "Lossless conversion between Atlassian Document Format and
+      extended markdown" until 7 restores HTML.
 - [x] **5a — Rename to `@larvit/adf-codec`.**
 - [x] **5b — The consumer's error surface.**
   - [x] **5b1 — The error's source position.**
@@ -137,11 +163,77 @@ The numbering is the order the work was planned in, not the order it ships.
 - [ ] **6 — The HTML dialect spec (`0.3.0`).** Element-by-element mapping, the `data-*` fidelity
       scheme, the opaque-carry form, and the documented foreign-element set `htmlToAdf` accepts.
 - [ ] **7 — HTML, ship `0.3.0`.** `adfToHtml`, `htmlToAdf`, the composed `markdownToHtml` /
-      `htmlToMarkdown`. CommonMark spec suite runs against `markdownToHtml` from here (§10).
+      `htmlToMarkdown`. CommonMark spec suite runs against `markdownToHtml` from here (§10). The
+      README's tagline and `package.json`'s `description` regain HTML (5g).
 - [ ] **8 — CLI.** A later goal, shaped around the personas once the library exists.
 - [ ] **9 — The online sandbox.** A web page with two textboxes converting back and forth between ADF and markdown, powered by the library's browser build.
-- [ ] **10 — Lossy conversion (`0.2.0`).** A direction that only converts what Markdown actually supports, keeping the ADF's data while dropping what markdown cannot hold — format, design and the richer nodes.
+- [ ] **10 — Lossy conversion (`0.2.0`).** Markdown other tools render readably, to and from ADF,
-- [ ] **11 — Evaluate `@atlaskit/adf-schema` (`0.2.0`).** Whether to add `@atlaskit/adf-schema` as a dev dependency to use as truth for the ADF schema.
+      keeping the content while dropping what markdown cannot hold — format, design and the richer
+      nodes.
+      **Settled** (the maintainer, 2026-09-14): two exports composed around the lossless pair, so §1's
+      four conversions stay four. `adfToPlainMarkdown(doc)` reduces the document ADF→ADF and hands it
+      to `adfToMarkdown`; `plainMarkdownToAdf(markdown)` hands the markdown to `markdownToAdf` and
+      lifts the result ADF→ADF. Both carry markdown conventions, so the reduction sits in
+      `src/markdown/emit/`, the lift in `src/markdown/parse/` and what both read in `src/markdown/`
+      (§11). The markdown is the flavour without directives — CommonMark, the pipe table and `~~` —
+      plus the conventions below, chosen for readability from a survey of GitHub, GitLab, Gitea,
+      Obsidian, Pandoc, MkDocs, Docusaurus, Typora, Joplin, Logseq, Bear, Notion, Azure DevOps and
+      Discord, GitHub's renderer confirming each shape. Writing refuses only what the document guard
+      refuses (`not-an-adf-document`, `unsupported-document-version`, `unsupported-nesting-depth`)
+      and degrades every other shape; reading refuses what `markdownToAdf` refuses. A lifted node
+      carries no `localId`. The lift also reads other tools' spellings — type words in any case,
+      Obsidian's aliases, `[X]` — since it reads their output and never writes those spellings.
+      - A `panel` is an alert: the marker alone on the quote's first line, a blank `>`, then the body
+        (`> [!WARNING]`), in GitHub's five words by colour — info `NOTE`, note `IMPORTANT`, tip and
+        success `TIP`, warning `WARNING`, error `CAUTION`, custom `NOTE`. The lift reads those words
+        back (`NOTE` info, `IMPORTANT` note, `TIP` tip, `WARNING` warning, `CAUTION` error) and
+        Obsidian's by meaning (hint tip; success, check and done success; attention warning; danger,
+        failure, fail, missing and bug error; any other word info). Text after a marker in its
+        paragraph is the panel's first body paragraph.
+      - An `expand` or `nestedExpand` is Obsidian's folded callout, `> [!NOTE]- Title`, a blank `>`,
+        then the body. The lift reads a fold sign (`-` or `+`) as an expand whatever the word, the
+        rest of the marker's paragraph as its title, and an expand inside an expand as a
+        `nestedExpand`.
+      - A `taskList` is a bullet list whose items lead with `[x]` or `[ ]` (`- [x] Write the spec`).
+        The lift reads a list whose every item is so marked back as a `taskList` — a `blockTaskItem`
+        where an item holds more than one block, a nested task list moved beside its item — and
+        leaves mixed and ordered lists plain. A `decisionList` is a plain bullet list.
+      - `backgroundColor` is `==text==`, and the lift gives `==text==` the Atlassian editor's default
+        highlight colour.
+      - `layoutSection`/`layoutColumn`, `bodiedExtension`, `bodiedSyncBlock`, `multiBodiedExtension`
+        and `extensionFrame` unwrap to their body blocks in order; the CommonMark blocks keep their
+        spelling, attributes dropped.
+      - `mention` and `status` become their text, the mention's `@` kept; `emoji` its text or else its
+        `shortName`; `date` its ISO date in UTC (`2026-09-13`); `inlineCard`, `blockCard` and
+        `embedCard` a link to their `url`, dropped when they carry only `data`; a `mediaSingle`
+        holding an external image stays `![alt](url)`; `media`, `mediaGroup` and `mediaInline` their
+        `alt` text or nothing; `caption` its text as a paragraph; `extension`, `inlineExtension` and
+        `syncBlock` their `text` attribute or nothing; `placeholder` nothing; a node no row names, or
+        one standing where no spelling holds it, its blocks or its text.
+      - A table stays a pipe table: the first row becomes the header, a cell's blocks join on one line
+        with spaces, and spans and the cells they cover drop.
+      - `code`, `em`, `link`, `strike` and `strong` stay and every other mark drops, keeping its text —
+        `subsup` too, since `~2~` is a strike on GitHub; a link no CommonMark escape writes becomes its
+        text, and a mark run CommonMark's flanking or matching cannot spell drops its mark.
+      - A newline in text becomes a hard break and edge whitespace is trimmed; carriage returns and
+        null characters are removed; a paragraph line opening with a code span whose backticks would
+        read as a fence loses the code mark; an empty paragraph drops, and adjacent lists of one type
+        merge.
+      - Rejected in the survey: `~sub~` and `^sup^`, underline and colour spellings, raw HTML
+        (`<details>`, `<mark>`), MkDocs `!!!` and the `:::` admonition family, footnotes, definition
+        lists, wikilinks, embeds, tags, comments, TOC tokens, spoilers, task states past `[x]`/`[ ]`,
+        and lifting bare URLs, `@name`, `:shortcode:` or ISO dates into nodes.
+  - [ ] **10a — The reduction.** `adfToPlainMarkdown`'s ADF→ADF reduction, tests first, a test per
+        row above.
+  - [ ] **10b — The lift.** `plainMarkdownToAdf`'s ADF→ADF lift, tests first, a test per row it reads,
+        other tools' spellings included; the editor's default highlight colour looked up and cited.
+  - [ ] **10c — The exports.** `adfToPlainMarkdown` and `plainMarkdownToAdf` exported with their README
+        sections, and two properties over 4.2's generators: writing refuses only the guard's codes,
+        and markdown `adfToPlainMarkdown` wrote reads back through `plainMarkdownToAdf` and writes
+        again byte for byte. AGENTS.md §1 records the pair as composed around the lossless one.
+- [x] **11 — Atlassian's ADF schema as the tables' truth.**
+  - [x] **11a — The vendored schema.**
+  - [x] **11b — The gate.**
 - [ ] **12 — The `!adf:` re-spelling (`0.2.0`).** Replace the colon directive grammar with the
       namespaced prefix, a breaking change to the emitted contract (shipped `0.1.0`, so §8 makes it
       `0.2.0`). Forms: block container `!adf:name arg {attrs}` … `!adf:/name` — the `/` parts open
@@ -149,29 +241,71 @@ The numbering is the order the work was planned in, not the order it ships.
       length rule go and every container opens the constant `!adf:`; block leaf `!adf:name arg
       {attrs}` with no closer; inline node `!adf:name[content]{attrs}`; directive marks
       `!adf:border`/`subsup`/`textColor`/`underline` `[content]{attrs}`. Attributes and their
-      escaping stay `{key=value}`; the literal escape is `\!adf:`; a line opening `!adf:` claims as
+      escaping stay `{key=value}`; the literal escape is `\!adf:`. Leaf vs container is decided by
-      today's colon-run does. Leaf vs container is decided by the node's content model rather than
+      the node's content model rather than syntax — the `::`/`:::` split goes, a simplification the
-      syntax — the `::`/`:::` split and §4's name-set-independent recognition go, a simplification
+      carry makes safe (an unknown *block* node already rides the fence, not the directive). The
-      the carry makes safe (an unknown *block* node already rides the fence, not the directive).
+      carry's reserved name becomes `carry`, both spellings — the block fence info string `carry`
-      The carry's reserved name becomes `carry`, both spellings — the block fence info string
+      and the inline `!adf:carry{json="…"}` — named for what it does: it carries a node verbatim,
-      `` `carry` `` and the inline `!adf:carry{json="…"}` — named for what it does: it carries a node
+      never "unknown-node", since a known node no section spells where it stands rides it too. No
-      verbatim, never "unknown-node", since a known node no section spells where it stands rides it
+      `ConvertErrorCode` is added, removed or renamed, and the round-trip guarantee and the carry
-      too. A spelling change, not a semantic one: no `ConvertErrorCode` is added, removed or renamed,
+      both hold through it. Mechanical surface: the grammar in `spec/flavour.md`,
-      the round-trip guarantee and the carry both hold through it. Mechanical surface: the grammar in
+      `src/adf/block-directives.ts` + `inline-directives.ts`, `src/markdown/`'s
-      `spec/flavour.md`, `src/adf/block-directives.ts` + `inline-directives.ts`, `src/markdown/`'s
       `directive-syntax.ts`, `opaque-carry.ts` and the `emit/` + `parse/` readers, every corpus
-      fixture (round-trip, normalization and `errors/`), `spec.test.ts`'s prose reader, and the
+      fixture (round-trip, normalization and `errors/`), the prose reader over `spec/flavour.md`,
-      README's examples.
+      and the README's examples.
-  - [ ] **12a — The spec and the decision.** Rewrite `spec/flavour.md` to the `!adf:` grammar, and
+      **Settled** (the maintainer, 2026-09-13):
-        record the departures in `AGENTS.md` §4 (leaf/container by content model, carry renamed
+      - A line opening `!adf:name` is a block line when a space or the line's end follows the name,
-        `carry`).
+        and a paragraph when `[` or `{` does. Claiming stays syntactic and structure comes from the
-  - [ ] **12b — The emit side.** `adfToMarkdown` spells `!adf:` / `!adf:/name` / `!adf:carry`; its
+        tables: an unknown name is `unknown-directive-name` at the opener, whatever follows it.
-        fixtures re-spelled, green.
+      - An unescaped `!adf:` claims on its own anywhere inline: one completing no directive is
-  - [ ] **12c — The parse side and the round-trip.** `markdownToAdf` reads it back; the round-trip
+        `malformed-directive`, the emitter escapes every literal `!adf:`, and `!adf:hardBreak{}`
-        corpus, the `errors/` fixtures and the CommonMark spec suite re-spelled,
+        keeps its braces. Block and inline share the one `\!adf:` escape hint.
-        `markdownToAdf(adfToMarkdown(doc))` still equals `doc`.
+      - A closer names the innermost open container, crosses no list-item or blockquote edge,
-  - [ ] **12d — The README and the sweep.** The README's examples follow; sweep docs and fixtures
+        indents as a fence does and carries nothing after the name; anything else is
-        for any stale `::`/`:name` spelling.
+        `malformed-directive`.
+      - A node holding no content whose content model takes some is an empty opener–closer pair,
+        never a leaf.
+      - A spelled node's content model is frozen with its spelling: changing it is MAJOR (§8).
+      - The colon spellings are dropped, not refused: `0.1.0` markdown reads back as prose, `adf`
+        is no longer a reserved language, and `MIGRATION.md` tells a consumer to convert stored
+        markdown through `0.1.0`'s parser and `0.2.0`'s emitter.
+      - Inputs moving between codes ride the break: a leaf given a body, a container missing its
+        closer and `listBreak` with a body are `malformed-directive`, and an empty inline-body
+        container parses.
+      - Split by construct, each sub-item both directions: 55 of 78 round-trip fixtures feed both
+        the emit and the read-back test, so an emit-only chunk cannot land green.
+  - [ ] **12a — The spec and the decision.** `spec/flavour.md` rewritten to the `!adf:` grammar and
+        the settled answers above, no colon directive form left in it; AGENTS.md §4's directive
+        bullet and prior-art line, and §8's escape hints and `::adf`/`::listBreak` examples, name
+        the new forms, §8 gaining the frozen content model.
+  - [ ] **12b — The inline form.** Inline nodes, directive marks, `text` and the inline carry
+        `!adf:carry{json=…}` spelled and read as `!adf:name[content]{attrs}`, with the prefix claim
+        and its escape; the round-trip, normalization and `errors/` fixtures holding inline forms
+        re-spelled, and the gate green. The content slot of `emoji`, `mention` and `status` refuses a
+        text node carrying attributes as `unsupported-node-shape`, which it drops silently today (the
+        maintainer, 2026-09-14).
+  - [ ] **12c — The block form.** Openers and `!adf:/name` closers, leaf vs container by content
+        model, empty pairs, `listBreak` and the `carry` fence, spelled and read; the fence-length
+        rule and the corpus test's fence nesting check deleted; the remaining fixtures re-spelled
+        and `errors/` re-derived under the shifted codes, and the gate green.
+  - [ ] **12d — The README, `MIGRATION.md` and the sweep.** The README's examples and error tables
+        follow, `MIGRATION.md` linked from one README line; docs and fixtures swept for any stale
+        `::`/`:name` spelling.
+- [ ] **13 — The schema's gap attributes (`0.2.0`).** Spell the attributes 11b pins as gaps, in
+      12's grammar, and empty the list.
+      **Settled** (the maintainer, 2026-09-13): a link `[text](url "title")` cannot hold takes the
+      directive mark `!adf:link[text]{attrs}` — one carrying `collection`, `id` or `occurrenceKey`,
+      or an `href` or `title` no CommonMark escape writes — and a directive link CommonMark could
+      spell is `unsupported-node-shape`. That leaves `unspellable-link` no cause, so it leaves
+      `ConvertErrorCode` in `0.2.0`, §8 recording the removal.
+  - [ ] **13a — `rule` and `layoutSection`.** `rule`'s `color`, `style` and `weight` and
+        `layoutSection`'s `columnRuleStyle` join their tables and `spec/flavour.md` bullets, with
+        round-trip fixtures; their gap entries go.
+  - [ ] **13b — The directive link.** `link` spelled as above in both directions, with a round-trip
+        fixture per trigger, `spec/flavour.md`'s Marks section following; `unspellable-link` removed
+        from the code list, its `errors/` fixtures and the CommonMark suite's `unspellable`
+        exceptions it cures re-derived, and the README's code table and its "not every document
+        converts back" guarantee following; the gap list is empty.
 
 ## The ADF inventory to cover