Cut the empty-key and -0 grammar from the decisions into the spec, and cite item 65 as what ends the image gap

AGENTS.md

@@ -10,8 +10,14 @@ In `docs/decisions.md`:
 - Plain markdown is a flavour of the grammar
 - The round-trip is the product
 - Markdown in is a canonical fixpoint
-- Equality is editor-normal
+- Equality is deep
+- `!adf:textBreak{}` parts text CommonMark would join
+- An empty key spells `empty`
+- `-0` is spelled `-0`
+- Empty markdown is a document of no blocks
 - Unknown nodes ride the carry
+- The carry fence names the node type
+- A code block is a fence per text node
 - Foreign HTML sorts three ways
 - Names stay text
 - Directives under `!adf:`
@@ -42,6 +48,7 @@ In `docs/decisions.md`:
 - Firefox reads the build
 - The coverage floors
 - The size ratchet
+- The project ships under the comprehension floor until items 59, 60, 61 and 62 land
 - Properties on a fixed seed
 - The CommonMark suite checks three ways
 - The flavour spec is read as a source
@@ -162,12 +169,16 @@ nearest text, a candidate entry in that file's voice, and the instance it yields
 keeps collecting instances is wrong: rewrite it.
 
 Which output the audience expects — README goal 5 — is settled by a reader panel rather than
-asked: three fresh-context readers, one per README persona the conversion serves, each given only
+asked: three fresh-context readers, one per README persona the question serves, each given only
 `## Audience` and the input, writing what they expect before picking among outputs the goals
 allow, rendered, shuffled, with no rationale and nothing saying what is implemented. Three agreeing
 settle it; otherwise four more read, five of seven settle it, and less is a missing goal, asked.
 The verdict lands in `docs/decisions.md`.
 
+A writer panel settles every new or changed markdown or HTML spelling: a reader panel whose readers
+are the people who read and write that format (README `## Audience`). A panel of the developer
+personas settles a question about what an app relies on.
+
 ### Stated numbers
 
 A stated number — 500 levels, the branch floor — is kept; a chunk that cannot keep it asks, naming
@@ -180,3 +191,14 @@ and `todo.md` and trusting them over anything remembered from earlier iterations
 is a thin driver: each chunk's work runs in a fresh-context subagent holding this file as its
 charter, and the driver only relays maintainer questions, runs the review flow, merges, and cleans
 up. The loop stops when only maintainer-reserved acts remain.
+
+## 8. Scoring run
+
+The comprehension panel's fill-ins:
+
+- Language: TypeScript.
+- Kind: a pure-function document converter with hand-written parsers and emitters.
+- Domain: Atlassian Document Format and CommonMark parsing.
+- Domain docs: the CommonMark spec, ADF's JSON schema and `spec/flavour.md`.
+- 3am question: a viewer/editor app reports that a document it saved comes back with two text
+  nodes merged and a mark gone after `markdownToAdf(adfToMarkdown(doc))`.

CHANGELOG.md

@@ -2,10 +2,21 @@
 
 ## Unreleased
 
-- **Breaking:** directives, the opaque carry among them (now `carry`), are spelled under an `!adf:`
+- **Breaking:** directives, the inline opaque carry among them (now `!adf:carry{json="…"}`), are
-  prefix (`!adf:name … !adf:/name`, `!adf:name[content]{attrs}`, `!adf:name arg {attrs}`) in place
+  spelled under an `!adf:` prefix (`!adf:name … !adf:/name`, `!adf:name[content]{attrs}`,
-  of the `:::`/`::`/`:name` forms: text holding an unescaped `!adf:` is claimed, and `adf` is an
+  `!adf:name arg {attrs}`) in place of the `:::`/`::`/`:name` forms: text holding an unescaped
-  ordinary code block language. Convert stored markdown per `MIGRATION.md`.
+  `!adf:` is claimed. Convert stored markdown per `MIGRATION.md`.
+- **Breaking:** the block carry is a code fence whose info string `adf:<type>` names the node's
+  type, its body the node's JSON without `type`, and a code fence whose info string opens `adf:` is
+  claimed, and `adf` is an ordinary code block language. Convert stored markdown per `MIGRATION.md`.
+- **Breaking:** `markdownToAdf` and `plainMarkdownToAdf` read markdown holding no block as a
+  document whose `content` is empty, as Atlassian's schema requires; `!adf:doc {content=none}`
+  spells a document holding no `content` key.
+- `markdownToAdf(adfToMarkdown(doc))` deep-equals `doc` as `JSON.parse` builds it: two adjacent text
+  nodes CommonMark would read back as one are parted by `!adf:textBreak{}`, an empty `attrs`,
+  `content` or `marks` is spelled `{attrs=empty}`, `{content=empty}` or `{marks=empty}`, `-0` is
+  spelled `-0`, and a `codeBlock` of several text nodes is a fence per node. A `codeBlock` holding
+  other than plain text nodes rides the block carry, where it was refused.
 - **Breaking:** `unspellable-link` leaves `ConvertErrorCode`; a link whose `href` or `title` no
   CommonMark escape spells is written as `!adf:link[text]{attrs}`.
 - **Breaking:** some directive refusals carry `malformed-directive` where they carried

MIGRATION.md

@@ -5,8 +5,9 @@
 Directives moved under the `!adf:` prefix. `0.2.0` reads `0.1.0`'s spelling without an error,
 turning each directive into text and each carried node into an `adf` code block. Before `0.2.0`
 reads any `0.1.0` markdown, convert what is stored or in flight (an open editor, a queue) with the
-recipe below, and rewrite markdown your code writes or matches (templates, prompts, patterns) by
+recipe below, and rewrite markdown your code writes or matches (templates, prompts, patterns) by the
-the tables below. Stored ADF needs no change.
+tables below. Stored ADF needs one change: give a document holding no `content` key `content: []`.
+`0.1.0` built that shape from empty markdown, meaning the empty document.
 
 ### Convert markdown
 
@@ -22,15 +23,17 @@ import { markdownToAdf as markdownToAdf010 } from 'adf-codec-0.1'
 
 function migrateMarkdown(stored: string) {
   const parsed = markdownToAdf010(stored)
-  return parsed.ok ? adfToMarkdown(parsed.value) : parsed
+  // 0.1.0 dropped an empty content array, so a document with no content key meant an empty one.
+  return parsed.ok ? adfToMarkdown({ ...parsed.value, content: parsed.value.content ?? [] }) : parsed
 }
 ```
 
 - Convert each document once: a second pass can return ok while turning the directives into text.
   Stop `0.1.0` writing first, and record which documents are converted.
 - A refusal carrying `position` is `0.1.0`'s parse, which refused that markdown before too. One
-  without is `0.2.0`'s emit: store the document `markdownToAdf010` read as ADF rather than keeping
+  without is `0.2.0`'s emit: store the document `markdownToAdf010` read as ADF, with
-  the unconverted markdown.
+  `content: parsed.value.content ?? []` as the recipe gives it, rather than keeping the unconverted
+  markdown.
 
 ### Spellings
 
@@ -40,12 +43,12 @@ function migrateMarkdown(stored: string) {
 | `::media {id=a type=file}` | `!adf:media {id=a type=file}` |
 | `::taskItem TODO {localId=i}`: an empty `caption`, `decisionItem`, `paragraph` or `taskItem`, or an empty `heading` carrying `localId` | `!adf:taskItem TODO {localId=i}` then `!adf:/taskItem` |
 | `:mention[@Mikael]{id=5b10a2}` | `!adf:mention[@Mikael]{id=5b10a2}` |
-| the `adf` code fence and `:adf{json="…"}` | the `carry` code fence and `!adf:carry{json="…"}` |
+| the `adf` code fence and `:adf{json="…"}` | the `adf:<type>` code fence, its JSON without `type`, and `!adf:carry{json="…"}` |
 | `\:` keeps a directive literal | `\!adf:` keeps a directive literal |
 | `:adf{json="…"}` carrying a link for its `collection`, `id` or `occurrenceKey` | `!adf:link[text]{attrs}` |
 
 A colon run and `:name[` are plain text now, and `adf` an ordinary code block language; text
-holding an unescaped `!adf:` and a `carry` fence are claimed instead.
+holding an unescaped `!adf:` and a code fence whose info string opens `adf:` are claimed instead.
 
 ### Readings
 
@@ -54,6 +57,8 @@ Markdown the spelling table leaves alone, which `0.2.0` reads as a different doc
 | Input | `0.1.0` | `0.2.0` |
 | --- | --- | --- |
 | a link whose text already holds one (`[a<https://example.com/>b](/v)`) | marks every node the inner link does not, splitting the outer link around it | leaves the outer brackets literal text; write the pieces as separate links to keep them |
+| markdown holding no block (`markdownToAdf("")`) | `{ type: 'doc', version: 1 }` | `{ content: [], type: 'doc', version: 1 }`; `!adf:doc {content=none}` reads as the former |
+| a code fence whose info string opens `adf:` (```` ```adf:x ````) | a `codeBlock` with that language | the block carry, refusing a body that is not one node's canonical JSON; write `!adf:codeBlock {language="adf:x"}` around a bare fence to keep the code block |
 
 ### Error codes
 
@@ -63,6 +68,7 @@ it named converts.
 | Input | `0.1.0` | `0.2.0` |
 | --- | --- | --- |
 | a link whose `href` or `title` no CommonMark escape spells, on emit | `unspellable-link` | spells `!adf:link[text]{attrs}` |
+| a `codeBlock` holding other than plain text nodes, on emit | `unsupported-node-shape` | rides the block carry |
 | a leaf node given a body (`media`, `listBreak`) | `unsupported-node-shape` | `malformed-directive` |
 | a node with a block body written as a leaf (`panel`) | `unsupported-node-shape` | `malformed-directive` |
 | an empty node the `::taskItem` spelling row names, written as a leaf | parses | `malformed-directive` |

README.md

@@ -52,6 +52,10 @@ which is free text.
 - **LLM/agent pipeline** — hands documents to a model as markdown and writes the edits back.
   Relies on the round-trip and on markdown a reader half-knowing the lossless flavour can still edit.
 
+Behind those apps, the people who read and write the markdown, and later the HTML: product
+managers, engineers and support agents working in Atlassian products through a plugin or another
+UI. They know markdown and not ADF, and rely on every spelling saying what it means to them.
+
 ## The shape
 
 ```sh
@@ -171,7 +175,7 @@ Parsing — `markdownToAdf` and `plainMarkdownToAdf`, and `htmlToAdf` at `0.2.0`
 
 | Code | Fires when | What you can do |
 | --- | --- | --- |
-| `malformed-directive` | an `!adf:` the grammar cannot read — a prefix completing no directive, an unclosed container, `[content]` or `{attrs}`, a closer with no container of its name open, a leaf given a body, `{attrs}` out of order or duplicated, invalid JSON in a `carry` | write the spelling the message names, or escape the prefix — `\!adf:`, block and inline alike — to keep it literal text |
+| `malformed-directive` | an `!adf:` the grammar cannot read — a prefix completing no directive, an unclosed container, `[content]` or `{attrs}`, a closer with no container of its name open, a leaf given a body, `{attrs}` out of order or duplicated, invalid JSON in an opaque carry | write the spelling the message names, or keep it literal: escape the prefix — `\!adf:`, block and inline alike — or, for a code fence whose info string opens `adf:`, drop the info string and wrap the fence in `!adf:codeBlock {language="adf:…"}` |
 | `malformed-pipe-table` | a pipe row that is no pipe table — a missing or ragged `---` delimiter row, an alignment colon in it, or a row not opening with a pipe | open every row with a pipe and give the delimiter row the header's cell count; to keep the lines literal text instead, escape the leading pipe of every one — escaping a single row leaves the next to open a fresh table and fail the same way |
 | `unknown-directive-name` | a directive whose name is no node or mark this version spells | check the name in `spec/flavour.md`, or escape the prefix as `\!adf:`; the spelling itself is well formed, so a later minor may give the name meaning |
 | `unmappable-html` | the input holds an HTML construct the documented element set does not map, a comment and a processing instruction among them — at this version that is every raw HTML construct in markdown, the element set landing at `0.2.0` | remove the construct, or write what it holds in the lossless flavour |
@@ -194,25 +198,28 @@ emit refuses:
 | `unspellable-line-start` | a paragraph line begins with a code span whose backticks would read back as a code fence | put any text before the code span |
 | `unspellable-whitespace` | an `emoji`, `mention` or `status` holds a newline in the text its inline directive spells in the content slot | replace it with a space — an inline directive never spans lines |
 | `unsupported-nesting-depth` | blocks, marks, an attribute's JSON or a carried node's JSON nest past 500 levels | keep the ADF and pass the document over, or show it read-only; flatten the input where you are the one who wrote it |
-| `unsupported-node-shape` | a node carries an attribute, value, argument or body its type does not take, or lacks one it needs — or markdown writes as a directive a node or mark the lossless flavour spells as CommonMark | write the shape the message names; `spec/flavour.md` lists every type's attributes and body |
+| `unsupported-node-shape` | a node carries an attribute, value, argument or body its type does not take, or lacks one it needs — or markdown writes as a directive a node or mark the lossless flavour spells as CommonMark, or a reserved directive stands out of place: `!adf:textBreak{}` or `!adf:listBreak` parting nothing, `!adf:doc` anywhere but as the whole document | fix what the message names; `spec/flavour.md` lists every type's attributes and body |
 
 ## The guarantees
 
 Serves Goals 1, 3 and 4.
 
-- `markdownToAdf(adfToMarkdown(doc))` equals `doc` — unknown node types included, carried opaquely
+- `markdownToAdf(adfToMarkdown(doc))` deep-equals `doc` as JSON, for a document of plain objects
+  as `JSON.parse` builds them — every key and value as `doc` holds it, adjacent text nodes, an
+  empty `attrs`, `content` or `marks` and `-0` included, and unknown node types carried opaquely
   ([`docs/decisions.md`](https://gitea.larvit.se/larvit/adf-codec/src/branch/main/docs/decisions.md#unknown-nodes-ride-the-carry)).
 - Markdown this library reads, and markdown it writes, means what the CommonMark spec says; from
   `0.2.0`, well-formed HTML means what the HTML standard says, read or written. The bullets below
   name every exception.
 - Plain CommonMark is valid input to `markdownToAdf` apart from the raw HTML `unmappable-html`
-  names, with three carve-outs — literal text matching directive, pipe-table or strikethrough
+  names, with four carve-outs — literal text matching directive, pipe-table or strikethrough syntax,
-  syntax is claimed (escapable — `spec/flavour.md`) — and one gap: a CommonMark image fits only as
+  and a code fence whose info string opens `adf:`, are claimed (each can be kept literal —
-  its own title-less paragraph; mid-text and titled images are error results, save an image inside
+  `spec/flavour.md`) — and one gap: a CommonMark image fits only as its own title-less paragraph;
-  another's description, which flattens into the alt text. Converting back yields the library's
+  mid-text and titled images are error results, save an image inside another's description, which
-  canonical spelling, which round-trips byte-identically — where it converts back at all: a parse
+  flattens into the alt text. Converting back yields the library's canonical spelling, which
-  succeeding is no promise of that, so keep the source until the way back succeeds.
+  round-trips byte-identically — where it converts back at all: a parse succeeding is no promise of
-  ``` ` `` ` ``` reads cleanly and then refuses.
+  that, so keep the source until the way back succeeds. ``` ` `` ` ``` reads cleanly and then
+  refuses.
 - Four CommonMark spellings parse without an error and build a document the reference
   implementation renders differently: `[](/url)` and `[]()` stay literal text against CommonMark's
   empty link, a list continuing past a marker change stays one list against CommonMark's two, a
@@ -235,7 +242,7 @@ Serves Goals 1, 3 and 4.
   makes a call loop forever.
 - The emitted formats are semver surface
   ([`docs/decisions.md`](https://gitea.larvit.se/larvit/adf-codec/src/branch/main/docs/decisions.md#the-formats-are-api)).
-- **`0.2.0`** — `htmlToAdf(adfToHtml(doc))` equals `doc`; fidelity HTML cannot express rides
+- **`0.2.0`** — `htmlToAdf(adfToHtml(doc))` deep-equals `doc`; fidelity HTML cannot express rides
   `data-*` attributes. Foreign HTML maps a documented element set, which markdown's raw HTML reads
   through as well, and a construct outside it is an error; well-formed HTML only — no tag-soup
   recovery.

browser-tests/convert-corpus.js

@@ -1,16 +1,18 @@
 try {
   const { adfToMarkdown, isAdfDocument, markdownToAdf } = await import('/dist/index.js')
+  // WebDriver's JSON reads -0 back as 0, so a document crosses as JSON text with -0 tagged; run.js revives it.
+  const spelled = (result) => (result.ok ? { ok: true, value: JSON.stringify(result.value, (_, value) => (Object.is(value, -0) ? '\u0000-0' : value)) } : result)
   window.convertCorpus = (corpus) => ({
     errors: corpus.errors.map(({ markdown, name }) => ({ name, parsed: markdownToAdf(markdown) })),
-    normalization: corpus.normalization.map(({ markdown, name }) => ({ name, parsed: markdownToAdf(markdown) })),
+    normalization: corpus.normalization.map(({ markdown, name }) => ({ name, parsed: spelled(markdownToAdf(markdown)) })),
     realPayloads: corpus.realPayloads.map(({ json, name }) => {
       const adf = JSON.parse(json)
       const emitted = adfToMarkdown(adf)
-      return { emitted, isDocument: isAdfDocument(adf), name, parsed: emitted.ok ? markdownToAdf(emitted.value) : undefined }
+      return { emitted, isDocument: isAdfDocument(adf), name, parsed: emitted.ok ? spelled(markdownToAdf(emitted.value)) : undefined }
     }),
     roundTrip: corpus.roundTrip.map(({ json, markdown, name }) => {
       const adf = JSON.parse(json)
-      return { emitted: adfToMarkdown(adf), isDocument: isAdfDocument(adf), name, parsed: markdownToAdf(markdown) }
+      return { emitted: adfToMarkdown(adf), isDocument: isAdfDocument(adf), name, parsed: spelled(markdownToAdf(markdown)) }
     }),
   })
 } catch (cause) {

browser-tests/run.js

@@ -2,7 +2,6 @@ import assert from 'node:assert/strict'
 import { createServer } from 'node:http'
 import { extname, join } from 'node:path'
 import { readFileSync, readdirSync } from 'node:fs'
-import { toEditorNormal } from '../dist/adf/editor-normal.js'
 
 const contentTypes = { '.html': 'text/html; charset=utf-8', '.js': 'text/javascript' }
 const driver = 'http://127.0.0.1:4444'
@@ -50,6 +49,11 @@ function fixtureNames(kind, extension) {
     .sort()
 }
 
+// convert-corpus.js tags -0 so it survives WebDriver's JSON.
+function revived(text) {
+  return JSON.parse(text, (_, value) => (value === '\u0000-0' ? -0 : value))
+}
+
 function refusal(result) {
   return result.ok ? '' : `${result.error.code}: ${result.error.message}`
 }
@@ -107,7 +111,7 @@ for (const [index, { json, markdown, name }] of corpus.roundTrip.entries()) {
     assert.ok(result.emitted.ok, `it did not emit — ${refusal(result.emitted)}`)
     assert.equal(result.emitted.value, markdown)
     assert.ok(result.parsed.ok, `it did not parse — ${refusal(result.parsed)}`)
-    assert.deepEqual(toEditorNormal(result.parsed.value), JSON.parse(json))
+    assert.deepEqual(revived(result.parsed.value), JSON.parse(json))
   })
 }
 
@@ -115,7 +119,7 @@ for (const [index, { name }] of corpus.normalization.entries()) {
   const result = results.normalization[index]
   checking(name, result, () => {
     assert.ok(result.parsed.ok, `it did not parse — ${refusal(result.parsed)}`)
-    assert.deepEqual(toEditorNormal(result.parsed.value), JSON.parse(fixture(name, '.json')))
+    assert.deepEqual(revived(result.parsed.value), JSON.parse(fixture(name, '.json')))
   })
 }
 
@@ -125,7 +129,7 @@ for (const [index, { json, name }] of corpus.realPayloads.entries()) {
     assert.ok(result.isDocument, `${name}.json is no ADF document`)
     assert.ok(result.emitted.ok, `it did not emit — ${refusal(result.emitted)}`)
     assert.ok(result.parsed.ok, `it did not parse back — ${refusal(result.parsed)}`)
-    assert.deepEqual(toEditorNormal(result.parsed.value), JSON.parse(json))
+    assert.deepEqual(revived(result.parsed.value), JSON.parse(json))
   })
 }
 

corpus/README.md

@@ -18,8 +18,9 @@ One directory per contract kind:
   `reason`. `kind` is `mark-model` (the permanent count divergence from ADF's mark-per-text-node
   model), `unspellable` (parses but the flavour has no spelling) or `pending` (a parser gap).
 
-JSON is editor-normal (`docs/decisions.md` §Equality is editor-normal), two-space indent, keys
+JSON is two-space indent, keys sorted, and a document read back must deep-equal the fixture's
-sorted. `spec.json` is the vendored, upstream machine-readable suite, byte-exact from
+(`docs/decisions.md` §Equality is deep). `spec.json` is the vendored, upstream machine-readable
-[spec.commonmark.org](https://spec.commonmark.org/0.31.2/spec.json) (CommonMark 0.31.2, © John
+suite, byte-exact from [spec.commonmark.org](https://spec.commonmark.org/0.31.2/spec.json)
-MacFarlane, [CC-BY-SA-4.0](https://creativecommons.org/licenses/by-sa/4.0/)), and is not
+(CommonMark 0.31.2, © John MacFarlane,
-re-serialized by the corpus gate.
+[CC-BY-SA-4.0](https://creativecommons.org/licenses/by-sa/4.0/)), and is not re-serialized by the
+corpus gate.

corpus/errors/carry-fence-type-spellable.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/carry-fence-type-spellable.md

@@ -0,0 +1,5 @@
+```adf:
+{
+  "type": "blockCard"
+}
+```

corpus/errors/carry-fence-type-unspellable.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/carry-fence-type-unspellable.md

@@ -0,0 +1,3 @@
+```adf:\\
+{}
+```

corpus/errors/carry-fence-type.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/carry-fence-type.md

@@ -0,0 +1,5 @@
+```adf:blockCard
+{
+  "type": "blockCard"
+}
+```

corpus/errors/carry-invalid-json.md

@@ -1,3 +1,3 @@
-```carry
+```adf:blockCard
-{"type":
+{"attrs":
 ```

corpus/errors/code-block-empty-attrs-fence-language.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/code-block-empty-attrs-fence-language.md

@@ -0,0 +1,8 @@
+!adf:codeBlock {attrs=empty}
+```js
+a
+```
+```js
+b
+```
+!adf:/codeBlock

corpus/errors/code-block-empty-fence.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/code-block-empty-fence.md

@@ -0,0 +1,7 @@
+!adf:codeBlock
+```
+a
+```
+```
+```
+!adf:/codeBlock

corpus/errors/code-block-fence-languages.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/code-block-fence-languages.md

@@ -0,0 +1,8 @@
+!adf:codeBlock
+```js
+a
+```
+```ts
+b
+```
+!adf:/codeBlock

corpus/errors/directive-slot-carried-marks.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/directive-slot-carried-marks.md

@@ -0,0 +1 @@
+!adf:status[!adf:carry{json="{\"marks\":[],\"text\":\"x\",\"type\":\"text\"}"}]

corpus/errors/document-directive-bare.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/document-directive-bare.md

@@ -0,0 +1 @@
+!adf:doc

corpus/errors/document-directive-misplaced.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/document-directive-misplaced.md

@@ -0,0 +1,3 @@
+!adf:doc {content=none}
+
+Text.

corpus/errors/empty-attrs-with-attributes.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/empty-attrs-with-attributes.md

@@ -0,0 +1,3 @@
+!adf:panel info {attrs=empty}
+Text.
+!adf:/panel

corpus/errors/empty-content-with-body.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/empty-content-with-body.md

@@ -0,0 +1,3 @@
+!adf:paragraph {content=empty}
+Text.
+!adf:/paragraph

corpus/errors/empty-key-value.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/empty-key-value.md

@@ -0,0 +1,3 @@
+!adf:paragraph {attrs=none}
+Text.
+!adf:/paragraph

corpus/errors/empty-marks-wrapped.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/empty-marks-wrapped.md

@@ -0,0 +1 @@
+**!adf:date{marks=empty}**

corpus/errors/text-break-attributes.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/text-break-attributes.md

@@ -0,0 +1 @@
+a!adf:textBreak{x=y}b

corpus/errors/text-break-content.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/text-break-content.md

@@ -0,0 +1 @@
+a!adf:textBreak[x]b

corpus/errors/text-break-marks-differ.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/text-break-marks-differ.md

@@ -0,0 +1 @@
+**a**!adf:textBreak{}b

corpus/errors/text-break-misplaced.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/text-break-misplaced.md

@@ -0,0 +1 @@
+!adf:textBreak{}Hello

corpus/round-trip/block-nodes/code-block-carry.json

@@ -14,7 +14,19 @@
     },
     {
       "attrs": {
-        "language": "carry"
+        "language": "adf:blockCard"
+      },
+      "content": [
+        {
+          "text": "{\n  \"attrs\": {}\n}",
+          "type": "text"
+        }
+      ],
+      "type": "codeBlock"
+    },
+    {
+      "attrs": {
+        "language": "adf:"
       },
       "content": [
         {

corpus/round-trip/block-nodes/code-block-carry.md

@@ -1,12 +1,18 @@
-!adf:codeBlock {language=carry}
+```carry
-```
 {
   "type": "blockCard"
 }
 ```
+
+!adf:codeBlock {language="adf:blockCard"}
+```
+{
+  "attrs": {}
+}
+```
 !adf:/codeBlock
 
-!adf:codeBlock {language=carry}
+!adf:codeBlock {language="adf:"}
 ````
 ```
 ````

corpus/round-trip/block-nodes/code-block-text-nodes.json

@@ -0,0 +1,56 @@
+{
+  "content": [
+    {
+      "attrs": {
+        "language": "js"
+      },
+      "content": [
+        {
+          "text": "const a = 1\n",
+          "type": "text"
+        },
+        {
+          "text": "const b = 2",
+          "type": "text"
+        }
+      ],
+      "type": "codeBlock"
+    },
+    {
+      "content": [
+        {
+          "text": "a",
+          "type": "text"
+        },
+        {
+          "text": "```",
+          "type": "text"
+        },
+        {
+          "text": "\n",
+          "type": "text"
+        }
+      ],
+      "type": "codeBlock"
+    },
+    {
+      "attrs": {
+        "language": "has`tick",
+        "wrap": true
+      },
+      "content": [
+        {
+          "text": "x",
+          "type": "text"
+        },
+        {
+          "text": " y ",
+          "type": "text"
+        }
+      ],
+      "type": "codeBlock"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}

corpus/round-trip/block-nodes/code-block-text-nodes.md

@@ -0,0 +1,31 @@
+!adf:codeBlock
+```js
+const a = 1
+
+```
+```js
+const b = 2
+```
+!adf:/codeBlock
+
+!adf:codeBlock
+```
+a
+```
+````
+```
+````
+```
+
+
+```
+!adf:/codeBlock
+
+!adf:codeBlock {language="has\u0060tick" wrap=true}
+```
+x
+```
+```
+ y 
+```
+!adf:/codeBlock

corpus/round-trip/block-nodes/document-without-content.json

@@ -0,0 +1,4 @@
+{
+  "type": "doc",
+  "version": 1
+}

corpus/round-trip/block-nodes/document-without-content.md

@@ -0,0 +1 @@
+!adf:doc {content=none}

corpus/round-trip/block-nodes/empty-keys.json

@@ -0,0 +1,96 @@
+{
+  "content": [
+    {
+      "content": [],
+      "type": "paragraph"
+    },
+    {
+      "attrs": {},
+      "content": [
+        {
+          "text": "Plain words.",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [],
+      "type": "rule"
+    },
+    {
+      "attrs": {
+        "level": 2
+      },
+      "content": [
+        {
+          "text": "Title",
+          "type": "text"
+        }
+      ],
+      "marks": [],
+      "type": "heading"
+    },
+    {
+      "attrs": {
+        "panelType": "info"
+      },
+      "content": [],
+      "type": "panel"
+    },
+    {
+      "content": [
+        {
+          "attrs": {},
+          "content": [
+            {
+              "content": [
+                {
+                  "text": "Item",
+                  "type": "text"
+                }
+              ],
+              "type": "paragraph"
+            }
+          ],
+          "type": "listItem"
+        },
+        {
+          "content": [
+            {
+              "content": [
+                {
+                  "text": "Next",
+                  "type": "text"
+                }
+              ],
+              "type": "paragraph"
+            }
+          ],
+          "type": "listItem"
+        }
+      ],
+      "type": "bulletList"
+    },
+    {
+      "content": [],
+      "type": "codeBlock"
+    },
+    {
+      "attrs": {
+        "language": "js"
+      },
+      "marks": [],
+      "type": "codeBlock"
+    },
+    {
+      "attrs": {
+        "language": "js"
+      },
+      "content": [],
+      "type": "codeBlock"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}

corpus/round-trip/block-nodes/empty-keys.md

@@ -0,0 +1,35 @@
+!adf:paragraph {content=empty}
+!adf:/paragraph
+
+!adf:paragraph {attrs=empty}
+Plain words.
+!adf:/paragraph
+
+!adf:rule {content=empty}
+
+!adf:heading {level=2 marks=empty}
+Title
+!adf:/heading
+
+!adf:panel info {content=empty}
+!adf:/panel
+
+!adf:bulletList
+!adf:listItem {attrs=empty}
+Item
+!adf:/listItem
+!adf:listItem
+Next
+!adf:/listItem
+!adf:/bulletList
+
+!adf:codeBlock {content=empty}
+!adf:/codeBlock
+
+!adf:codeBlock {marks=empty}
+```js
+```
+!adf:/codeBlock
+
+!adf:codeBlock {content=empty language=js}
+!adf:/codeBlock

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

@@ -1,4 +1,4 @@
-```carry
+```adf:panel
 {
   "attrs": {
     "rounded": true
@@ -13,12 +13,11 @@
       ],
       "type": "paragraph"
     }
-  ],
+  ]
-  "type": "panel"
 }
 ```
 
-```carry
+```adf:panel
 {
   "attrs": {
     "panelType": "extra info"
@@ -33,8 +32,7 @@
       ],
       "type": "paragraph"
     }
-  ],
+  ]
-  "type": "panel"
 }
 ```
 

corpus/round-trip/combinations/negative-zero.json

@@ -0,0 +1,83 @@
+{
+  "content": [
+    {
+      "attrs": {
+        "order": -0
+      },
+      "content": [
+        {
+          "content": [
+            {
+              "content": [
+                {
+                  "text": "First",
+                  "type": "text"
+                }
+              ],
+              "type": "paragraph"
+            }
+          ],
+          "type": "listItem"
+        }
+      ],
+      "type": "orderedList"
+    },
+    {
+      "attrs": {
+        "level": -0
+      },
+      "content": [
+        {
+          "text": "Title",
+          "type": "text"
+        }
+      ],
+      "type": "heading"
+    },
+    {
+      "attrs": {
+        "extensionKey": "toc",
+        "extensionType": "com.atlassian.confluence.macro.core",
+        "parameters": {
+          "maxLevel": -0
+        }
+      },
+      "type": "extension"
+    },
+    {
+      "content": [
+        {
+          "attrs": {
+            "data": [
+              -0
+            ],
+            "url": "https://example.com/"
+          },
+          "type": "inlineCard"
+        },
+        {
+          "marks": [
+            {
+              "attrs": {
+                "color": "#000000",
+                "size": -0
+              },
+              "type": "border"
+            }
+          ],
+          "text": "x",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "attrs": {
+        "x": -0
+      },
+      "type": "blockCard"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}

corpus/round-trip/combinations/negative-zero.md

@@ -0,0 +1,21 @@
+!adf:orderedList {order=-0}
+!adf:listItem
+First
+!adf:/listItem
+!adf:/orderedList
+
+!adf:heading {level=-0}
+Title
+!adf:/heading
+
+!adf:extension {extensionKey=toc extensionType="com.atlassian.confluence.macro.core" parameters="{\"maxLevel\":-0}"}
+
+!adf:inlineCard{data="[-0]" url="https://example.com/"}!adf:border[x]{color="#000000" size=-0}
+
+```adf:blockCard
+{
+  "attrs": {
+    "x": -0
+  }
+}
+```

corpus/round-trip/commonmark-subset/document-empty.json

@@ -1,4 +1,5 @@
 {
+  "content": [],
   "type": "doc",
   "version": 1
 }

corpus/round-trip/inline-nodes/empty-keys.json

@@ -0,0 +1,98 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "attrs": {},
+          "type": "date"
+        },
+        {
+          "text": " ",
+          "type": "text"
+        },
+        {
+          "content": [],
+          "type": "date"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "a",
+          "type": "text"
+        },
+        {
+          "marks": [],
+          "type": "hardBreak"
+        },
+        {
+          "text": "b",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "attrs": {
+            "id": "x",
+            "text": "@M"
+          },
+          "content": [],
+          "type": "mention"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "bare",
+          "type": "text"
+        },
+        {
+          "marks": [],
+          "text": "marked",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "marks": [
+            {
+              "attrs": {},
+              "type": "em"
+            }
+          ],
+          "text": "x",
+          "type": "text"
+        },
+        {
+          "text": " and ",
+          "type": "text"
+        },
+        {
+          "attrs": {
+            "shortName": ":a:"
+          },
+          "marks": [
+            {
+              "attrs": {},
+              "type": "strong"
+            }
+          ],
+          "type": "emoji"
+        }
+      ],
+      "type": "paragraph"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}

corpus/round-trip/inline-nodes/empty-keys.md

@@ -0,0 +1,9 @@
+!adf:date{attrs=empty} !adf:date{content=empty}
+
+a!adf:hardBreak{marks=empty}b
+
+!adf:mention[@M]{content=empty id=x}
+
+bare!adf:carry{json="{\"marks\":[],\"text\":\"marked\",\"type\":\"text\"}"}
+
+!adf:carry{json="{\"marks\":[{\"attrs\":{},\"type\":\"em\"}],\"text\":\"x\",\"type\":\"text\"}"} and !adf:carry{json="{\"attrs\":{\"shortName\":\":a:\"},\"marks\":[{\"attrs\":{},\"type\":\"strong\"}],\"type\":\"emoji\"}"}

corpus/round-trip/inline-nodes/text-break.json

@@ -0,0 +1,154 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "text": "Hello, ",
+          "type": "text"
+        },
+        {
+          "text": "world",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "marks": [
+            {
+              "type": "strong"
+            }
+          ],
+          "text": "Hello, ",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "strong"
+            }
+          ],
+          "text": "world",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "marks": [
+            {
+              "type": "code"
+            }
+          ],
+          "text": "a",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "code"
+            }
+          ],
+          "text": "b",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "marks": [
+            {
+              "attrs": {
+                "href": "https://example.com/"
+              },
+              "type": "link"
+            }
+          ],
+          "text": "a",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "attrs": {
+                "href": "https://example.com/"
+              },
+              "type": "link"
+            }
+          ],
+          "text": "b",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "Line\n",
+          "type": "text"
+        },
+        {
+          "text": "next",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "marks": [
+            {
+              "type": "underline"
+            }
+          ],
+          "text": "a",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "underline"
+            }
+          ],
+          "text": "b",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "marks": [
+            {
+              "attrs": {},
+              "type": "underline"
+            }
+          ],
+          "text": "a",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "underline"
+            }
+          ],
+          "text": "b",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}

corpus/round-trip/inline-nodes/text-break.md

@@ -0,0 +1,13 @@
+Hello, !adf:textBreak{}world
+
+**Hello, !adf:textBreak{}world**
+
+`a`!adf:textBreak{}`b`
+
+[a!adf:textBreak{}b](https://example.com/)
+
+Line!adf:text{text="\n"}!adf:textBreak{}next
+
+!adf:underline[a!adf:textBreak{}b]
+
+!adf:underline[a]{attrs=empty}!adf:underline[b]

corpus/round-trip/opaque-carry/carry-in-wrappers.md

@@ -1,17 +1,15 @@
-> ```carry
+> ```adf:blockCard
 > {
 >   "attrs": {
 >     "url": "https://example.com/quoted"
->   },
+>   }
->   "type": "blockCard"
 > }
 > ```
 
-- ```carry
+- ```adf:blockCard
   {
     "attrs": {
       "url": "https://example.com/listed"
-    },
+    }
-    "type": "blockCard"
   }
   ```

corpus/round-trip/opaque-carry/code-block-children.json

@@ -0,0 +1,35 @@
+{
+  "content": [
+    {
+      "attrs": {
+        "language": "js"
+      },
+      "content": [
+        {
+          "marks": [
+            {
+              "type": "strong"
+            }
+          ],
+          "text": "const a = 1",
+          "type": "text"
+        }
+      ],
+      "type": "codeBlock"
+    },
+    {
+      "content": [
+        {
+          "text": "a",
+          "type": "text"
+        },
+        {
+          "type": "hardBreak"
+        }
+      ],
+      "type": "codeBlock"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}

corpus/round-trip/opaque-carry/code-block-children.md

@@ -0,0 +1,32 @@
+```adf:codeBlock
+{
+  "attrs": {
+    "language": "js"
+  },
+  "content": [
+    {
+      "marks": [
+        {
+          "type": "strong"
+        }
+      ],
+      "text": "const a = 1",
+      "type": "text"
+    }
+  ]
+}
+```
+
+```adf:codeBlock
+{
+  "content": [
+    {
+      "text": "a",
+      "type": "text"
+    },
+    {
+      "type": "hardBreak"
+    }
+  ]
+}
+```

corpus/round-trip/opaque-carry/unknown-block.md

@@ -1,23 +1,21 @@
-```carry
+```adf:blockCard
 {
   "attrs": {
     "url": "https://example.com/roadmap"
-  },
+  }
-  "type": "blockCard"
 }
 ```
 
 !adf:panel info
 The card below has no spelling yet.
 
-```carry
+```adf:embedCard
 {
   "attrs": {
     "layout": "wide",
     "url": "https://example.com/board",
     "width": 100
-  },
+  }
-  "type": "embedCard"
 }
 ```
 !adf:/panel

corpus/round-trip/opaque-carry/unknown-type-spelling.json

@@ -0,0 +1,21 @@
+{
+  "content": [
+    {
+      "attrs": {
+        "url": "https://example.com/"
+      },
+      "type": "has`tick"
+    },
+    {
+      "type": ""
+    },
+    {
+      "type": " padded"
+    },
+    {
+      "type": "two words"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}

corpus/round-trip/opaque-carry/unknown-type-spelling.md

@@ -0,0 +1,24 @@
+```adf:
+{
+  "attrs": {
+    "url": "https://example.com/"
+  },
+  "type": "has`tick"
+}
+```
+
+```adf:
+{
+  "type": ""
+}
+```
+
+```adf:
+{
+  "type": " padded"
+}
+```
+
+```adf:two words
+{}
+```

docs/decisions.md

@@ -14,7 +14,7 @@ a backslash reach them intact; what the flavour cannot spell reduces ADF→ADF a
 2026-08-23, real payloads 2026-09-15, the maintainer. Goal 1. Valid while a consumer saves back
 through the lossless pair.
 
-`markdownToAdf(adfToMarkdown(doc))` and `htmlToAdf(adfToHtml(doc))` must equal `doc` — anything
+`markdownToAdf(adfToMarkdown(doc))` and `htmlToAdf(adfToHtml(doc))` must deep-equal `doc` — anything
 less silently destroys content an editor could not represent, in a document it did not author.
 When losslessness and readability conflict, losslessness wins. Round-trip equality is a property
 tested over a checked-in corpus (`corpus/README.md`), not a claim made in prose. Its real payloads
@@ -31,27 +31,92 @@ where there is a way back. CommonMark spells some things the flavour has no esca
 paragraph opening with a code span whose backticks read back as a fence — so a parse succeeding
 does not imply a spellable document; `corpus/commonmark-spec/exceptions.json` names those.
 
-## Equality is editor-normal
+## Equality is deep
 
-2026-08-24, the maintainer. Goal 1. Valid while markdown cannot tell apart the ADF shapes this
+2026-08-24, deep 2026-10-03, the maintainer. Goal 1. Valid while a pipeline or a bot can build a
-merges.
+shape the editor would not.
 
-"Equals" is structural equality over editor-normal ADF — adjacent text nodes with identical marks
+"Equals" is deep equality over the document's JSON values: `assert.deepStrictEqual` on plain objects
-and no attributes merged, JSON number semantics, an empty attrs object, marks array or content
+as `JSON.parse` builds them, since ADF is JSON. Every key and value in `doc` counts, including two
-array the absent key — the only domain markdown can restore.
+adjacent text nodes, an empty `attrs`, `content` or `marks`, and `-0`. Neither side is normalized.
-`todo.md` item 40 replaces this with deep equality (2026-09-28, the maintainer).
+CommonMark's spelling stays wherever a document holds none of those shapes. The plain reader builds
+what is written, as `markdownToAdf` does. Only the plain writer is lossy: its reduction reads and
+writes editor-normal ADF — adjacent text nodes of identical marks and no attributes merged, `-0` as
+`0`, and an empty `attrs`, `content` or `marks` the absent key, but the doc's `content` — so two
+documents the editor holds equal write the same plain markdown.
+
+## `!adf:textBreak{}` parts text CommonMark would join
+
+2026-10-03, the maintainer. Goal 1. Valid while CommonMark reads adjacent text as one run.
+
+Two adjacent text nodes CommonMark would read back as one are parted by the reserved inline leaf
+`!adf:textBreak{}`, mirroring `!adf:listBreak`: a leaf building no node keeps both nodes and asks
+nothing of the text around it. A code span holds no directive, so the spans close and reopen
+around the leaf. The grammar: `spec/flavour.md` §Inline nodes, **Adjacent text nodes**.
+
+## An empty key spells `empty`
+
+2026-10-03, a writer panel and the maintainer. Goals 1 and 5. Valid while no attribute value
+spells an empty object or array.
+
+An `attrs`, `content` or `marks` key holding an empty object or array is the reserved key with the
+bare value `empty`, so an empty pair stays the node holding no content key. A writer panel chose
+the spelling, 5 of 7. The grammar: `spec/flavour.md` §Directives, **Attributes**, and §Marks.
+
+## `-0` is spelled `-0`
+
+2026-10-03, the maintainer. Goal 1. Valid while JSON's own serialization writes `-0` as `0`.
+
+`-0` is spelled `-0` wherever the flavour writes a number or a JSON value, since JSON's grammar
+reads it back as `-0` and no list marker spells the sign. The grammar: `spec/flavour.md` §Block
+nodes and §The CommonMark blocks.
+
+## Empty markdown is a document of no blocks
+
+2026-10-03, a writer panel and the maintainer. Goals 1 and 5. Valid while ADF's schema requires
+`content` on `doc`.
+
+Markdown holding no block reads as `{ content: [], type: 'doc', version: 1 }`, the document
+`spec/adf-schema/full.json` requires. A document holding no `content` key is
+`!adf:doc {content=none}` as its only block, and a named error anywhere else. The writer panel split
+4 for `none` and 3 for `absent`, and the maintainer chose `none`; all seven rejected a bare
+`!adf:doc`.
 
 ## Unknown nodes ride the carry
 
-2026-08-23, extended to misplaced known nodes 2026-08-26, the maintainer. Goal 1. Valid while ADF
+2026-08-23, extended to misplaced known nodes 2026-08-26 and to code block children 2026-10-03, the
-holds nodes, or node positions, this library does not spell.
+maintainer. Goal 1. Valid while ADF holds nodes, or node positions, this library does not spell.
 
 An unknown ADF node is carried opaquely — raw JSON rides a dedicated syntax in both formats and
 restores to a deep-equal node. The round-trip holds for documents newer than the library. So does
 a known node no section spells where it stands: a markdown serializer spells a node by type without
-checking its position, and refusing loses a document ADF itself keeps in an `unsupportedBlock`.
+checking its position, and refusing loses a document ADF itself keeps in an `unsupportedBlock`. A
-Where a container's own spelling cannot hold the child it has — a `bulletList` holding other than
+`codeBlock` holding a child no fence holds — anything but a text node carrying no marks, `attrs` or
-`listItem`, a `codeBlock` other than text — the error result names that instead.
+`content` — rides the carry whole.
+
+## The carry fence names the node type
+
+2026-10-03, the maintainer. Goals 1 and 5. Valid while a code fence's info string reads back
+verbatim.
+
+The block carry is a code fence whose info string `adf:<type>` names the node's type, its body the
+node's JSON without `type`: ```` ```adf:blockCard ````. A type no info string carries back — by the
+rule a code language follows — leaves the info string `adf:` and keeps `type` in the body. Every
+info string opening `adf:` is reserved, so a `codeBlock` whose language opens so takes the
+`language` attribute, and `carry` is an ordinary language. A body holding `type` under a named type,
+or a fence whose info string is `adf:` alone while its body's `type` could be spelled in the info
+string, is `unsupported-node-shape`. The reservation claims a fence CommonMark reads as code until
+`todo.md` item 43 gives CommonMark its own reader.
+
+## A code block is a fence per text node
+
+2026-10-03, the maintainer. Goal 1. Valid while ADF holds a code block's text in more than one
+node.
+
+A `codeBlock` holding several text nodes is the `!adf:codeBlock` container holding one fence per
+node, so each node keeps its own text. The fences carry one info string, since ADF holds one
+language, and none is empty beside another, since a text node holds text. The grammar:
+`spec/flavour.md` §The CommonMark blocks, the `codeBlock` bullet.
 
 ## Foreign HTML sorts three ways
 
@@ -97,7 +162,9 @@ opener nests by itself and leaf versus container falls out of the node's content
 2026-08-23, the maintainer. Goal 4. Valid while prose rarely writes the shapes the carve-outs claim.
 
 Plain CommonMark is a subset, with carve-outs (`spec/flavour.md`): literal text shaped like a
-directive, a pipe table or a `~~` pair is claimed — plus one image gap.
+directive, a pipe table or a `~~` pair is claimed, and so is a code fence whose info string opens
+`adf:` (§The carry fence names the node type) — plus one image gap. `todo.md` item 43 ends the
+claims, giving CommonMark its own reader, and `todo.md` item 65 ends the image gap.
 
 ## Tables
 
@@ -292,13 +359,14 @@ handles one cause alike whichever node, attribute or direction raised it.
   colon rather than ADF's missing column model doing it. What the grammar itself refuses stays a
   claim code, key order among it, and a leaf given a body is refused at its opener, as a container
   missing its closer is (2026-09-16).
-- A directive whose name reads back to no node is `unknown-directive-name` rather than a claim
+- A directive whose name reads back to no node is `unknown-directive-name` rather than a claim code
-  code — the spelling is well formed, and telling that apart from a typo is what a consumer
+  — the spelling is well formed, and telling that apart from a typo is what a consumer switches on
-  switches on when a later MINOR gives the name meaning. A reserved name is a known name, so never
+  when a later MINOR gives the name meaning. A reserved name is a known name, so never that code,
-  that code, and the two the flavour reserves part on form: a form the grammar does not have is a
+  and the names the flavour reserves part on form: a form the grammar does not have is a claim code
-  claim code — `!adf:carry`, whose carry is the fence — and a well-formed form in the wrong place
+  — `!adf:carry`, whose carry is the fence — and a well-formed form in the wrong place is
-  is `unsupported-node-shape`, `!adf:listBreak` parting anything but two adjacent lists of one
+  `unsupported-node-shape`, `!adf:listBreak` parting anything but two adjacent lists of one type,
-  type (2026-09-01).
+  `!adf:textBreak{}` anything but two adjacent text nodes CommonMark would read back as one,
+  `!adf:doc` standing beside another block (2026-09-01, the text break and `doc` 2026-10-03).
 - A well-formed directive the node tables refuse — an attribute a node does not hold or spells
   elsewhere, a value outside its kind or its canonical spelling, an argument, or a body of a shape
   its content model does not take — is `unsupported-node-shape`, the emitter's code for the same
@@ -422,6 +490,21 @@ config gone missing fails the leg instead of falling back to oxlint's own defaul
 `--deny-warnings`, since a rule from a category this config never names arrives as a warning it
 exits 0 on.
 
+## The project ships under the comprehension floor until items 59, 60, 61 and 62 land
+
+2026-10-03, the maintainer. KISS, a technical principle, and its comprehension floor of 7. Valid
+while `todo.md` items 59, 60, 61 and 62 are open.
+
+A four-seat comprehension panel scored the project 6 against the floor of 7. The scores are the
+baseline: a later panel may not score lower on any dimension.
+
+| Seat | Navigation | Locality | Shape | Self-sufficiency | Overall |
+|---|---|---|---|---|---|
+| Junior | 6.5 | 5.5 | 6 | 5.5 | 6 |
+| Mid | 7 | 5.5 | 6 | 5 | 5.5 |
+| Senior | 7 | 5.5 | 6.5 | 5.5 | 6 |
+| Architect | 6 | 5.5 | 5.5 | 6 | 6 |
+
 ## Properties on a fixed seed
 
 2026-09-14, the maintainer. Goal 1. Valid while a red gate must reproduce.
@@ -568,8 +651,8 @@ is the markdown flavour's choice, not ADF's.
 
 ## The source parts by ADF and format
 
-2026-08-27, placement 2026-09-18, `adf/`'s bar 2026-09-21, the maintainer. Goal 2. Valid while
+2026-08-27, placement 2026-09-18, `adf/`'s bar 2026-09-21, `plain/` 2026-10-03, the maintainer.
-each format has a reader and a writer through ADF.
+Goal 2. Valid while each format has a reader and a writer through ADF.
 
 `src/adf/` holds ADF's own knowledge, imports no format, and is where a construct both formats read
 lives: the question is answered in ADF's vocabulary — a node type, an attribute kind, a content
@@ -582,13 +665,14 @@ them. A primitive knowing neither ADF nor a format stays at `src/` root. A const
 `spec/flavour.md` draws, and a placement nothing here settles goes beside its only reader, or in
 what both read where there are two.
 
-Each format directory parts into `emit/` (ADF→format) and `parse/` (format→ADF), the rest of it
+A flavour's own code, both directions included, sits in its own directory: `markdown/plain/`.
-holding what both directions read. A construct's reader lives there beside the regex the emitter
+Otherwise each format directory parts into `emit/` (ADF→format) and `parse/` (format→ADF), the rest
-escapes against, so the two cannot drift; a reader with no emit counterpart goes in `parse/`,
+of it holding what both directions read. A construct's reader lives there beside the regex the
-unless it is part of a construct that side already holds — a grammar stays in one file rather than
+emitter escapes against, so the two cannot drift; a reader with no emit counterpart goes in
-splitting across the seam. A rule both directions must answer alike — whether a list marker
+`parse/`, unless it is part of a construct that side already holds — a grammar stays in one file
-interrupts a paragraph — is one function there too, never a copy per direction, however
+rather than splitting across the seam. A rule both directions must answer alike — whether a list
-conservative the copy would be. Where the rule is the emitter's own choice, input consults it
+marker interrupts a paragraph — is one function there too, never a copy per direction, however
-rather than restating it, and that is the only import `parse/` takes from `emit/` —
+conservative the copy would be. Where the rule is the emitter's own choice, input consults it rather
+than restating it, and that is the only value import `parse/` takes from `emit/` —
 `commonMarkSpelling` and `openingLinkTakesDirective` — so no fixture the emitter writes can be
 refused, and a spelling the emitter refuses gives its own error rather than a second name for it.

spec/flavour.md

@@ -1,12 +1,14 @@
 # The markdown flavour
 
 The grammar of the extended markdown `adfToMarkdown` emits and `markdownToAdf` parses. Plain
-CommonMark is a subset apart from raw HTML (below), with three carve-outs: literal text that matches
+CommonMark is a subset apart from raw HTML (below), with four carve-outs: literal text that matches
-directive syntax below or reads as a pipe table is claimed by the flavour, and a matched `~~` pair
+directive syntax below or reads as a pipe table is claimed by the flavour, a matched `~~` pair
-spells `strike` (escape the `!adf:`, `|` or `~` to keep it literal) — and one gap: a CommonMark
+spells `strike` (escape the `!adf:`, `|` or `~` to keep it literal), and a code fence whose info
-image fits only as its own title-less paragraph — mid-text and titled images are named errors. The
+string opens `adf:` is the opaque carry (drop the info string and wrap the fence in
-emitted form is contract (`docs/decisions.md` §The formats are API). Per-node syntaxes build on this
+`!adf:codeBlock {language="adf:…"}` to keep it code) — and one gap: a CommonMark image fits only as
-grammar in the sections below.
+its own title-less paragraph — mid-text and titled images are named errors. The emitted form is
+contract (`docs/decisions.md` §The formats are API). Per-node syntaxes build on this grammar in the
+sections below.
 
 ## Canonical form
 
@@ -44,7 +46,8 @@ normalizes to it through the round-trip.
   CommonMark admits no spelling — the end of a block, inside an ATX heading — or where the node
   carries an attribute, it is the inline directive.
 - An empty paragraph — real payloads carry them — is an `!adf:paragraph` … `!adf:/paragraph` pair
-  holding nothing.
+  holding nothing, and one whose `content` is an empty array the pair
+  `!adf:paragraph {content=empty}` … `!adf:/paragraph` (Attributes).
 - Links `[text](url)`; `<…>` around a destination containing spaces, `<>` an empty one beside a
   title; title in double quotes. A backslash escapes a parenthesis the destination leaves
   unbalanced, and a quote inside the title; a balanced pair stays bare. `<url>` autolink form only
@@ -67,7 +70,10 @@ normalizes to it through the round-trip.
   matching below, which is what lets the emitter decide its own pairings.
 - Blocks separated by one blank line at document level, inside a blockquote and between CommonMark
   blocks; inside a directive container a pair holding a directive block takes none. No trailing
-  whitespace outside a code block's content, single trailing newline; a document with no blocks is the empty string.
+  whitespace outside a code block's content, single trailing newline. A document whose `content` is
+  an empty array is the empty string, and markdown holding no block reads back to it; a document
+  holding no `content` key is the leaf `!adf:doc {content=none}` as its only block, which is a
+  named error anywhere else or spelled any other way.
 
 ## Directives
 
@@ -79,9 +85,11 @@ result naming it at the opener, whatever follows it — so output an old emitter
 escaped, and erroring input gaining meaning later is MINOR, never a reparse (`docs/decisions.md`
 §The formats are API). Each name belongs to one position, and a name the other one spells — a mark
 or an inline node written as a block directive, a block node written inline — is a different error,
-naming the spelling it takes. Two reserved names read back to no node: `carry` for the opaque carry,
+naming the spelling it takes. Four reserved names read back to no node: `carry` for the inline
-as both directive name and fence info string, and `listBreak` for the leaf that parts two adjacent
+opaque carry, `listBreak` for the leaf that parts two adjacent lists and `doc` for a document
-lists (Canonical form).
+holding no `content` key (Canonical form), and `textBreak` for the leaf that parts two text nodes
+(Inline nodes). Every fence info string opening `adf:` is reserved for the block carry (The opaque
+carry).
 
 **Claiming**: an unescaped `!adf:` claims wherever it stands. What follows picks the form: `/name`
 closes a container, and a name picks by what follows it in turn — a space or the line's end a block
@@ -142,6 +150,13 @@ ends the name (`!adf:hardBreak{}`). Input reads that spelling alone: keys out of
 quoted where bare carries it, an escape longer than it need be, an empty `{attrs}` on a block line
 or after a `[content]`, and a number or `json` value outside its canonical JSON spelling are each a
 named error naming the spelling to write instead.
+`attrs`, `content` and `marks` are reserved keys on every directive — block, inline node and mark —
+whose bare value `empty` spells the node's or mark's key holding an empty object or array:
+`!adf:underline[a]{attrs=empty}`, `!adf:date{content=empty}`, `!adf:hardBreak{marks=empty}`. A
+container spelling `content=empty` closes with no body; `attrs=empty` stands beside no other
+attribute, argument or content slot; and an inline node spelling `marks=empty` stands inside no
+mark spelling. Any other value of a reserved key is a named error, except on a block's `marks`
+(Block nodes).
 
 **Escaping**: the emitter backslash-escapes whatever literal text would otherwise parse as
 directive syntax — every literal `!adf:`, `]` inside content, a bracket a link's destination and
@@ -163,15 +178,19 @@ and restores to a deep-equal node. A carry may hold a node the emitter spells na
 unreinterpreted, and the next emit spells it canonically (`docs/decisions.md` §The round-trip is the
 product). Block and inline positions canonicalize differently, each fitting where it sits:
 
-- **Block position**: a fenced code block with info string `carry`, body = the node's JSON —
+- **Block position**: a fenced code block with info string `adf:` and the node's type, body = the
-  two-space indent, object keys sorted.
+  node's JSON without its `type` — two-space indent, object keys sorted: ```` ```adf:blockCard ````.
+  A type no info string carries back, by the rule a `codeBlock`'s language follows, leaves the info
+  string `adf:` and keeps `type` in the body. A body holding `type` under a named type, or a fence
+  whose info string is `adf:` alone while its body's `type` could be spelled in the info string, is
+  a named error.
 - **Inline position**: `!adf:carry{json="…"}` — compact serialization (keys sorted, no whitespace),
   JSON-string-escaped into the attribute.
 
-The info string `carry` is reserved: a genuine `codeBlock` whose `language` is exactly `carry` takes
+Every info string opening `adf:` is reserved: a genuine `codeBlock` whose `language` opens so takes
 the attribute the section below keeps for a language no info string holds, so the reservation
-stays absolute.
+stays absolute. In block-directive position `!adf:carry` is a named error — the carry's block form
-In block-directive position `!adf:carry` is a named error — the carry's block form is the fence.
+is the fence.
 
 ## Raw HTML in input
 
@@ -193,13 +212,14 @@ Each section lists attributes as `name (type)`. A parenthesized value set docume
 payloads hold; the type stays string and any value round-trips verbatim. Values map to attrs by
 type: strings verbatim, numbers and booleans in canonical JSON spelling — quoted where not bare
 (`width="33.33"`) — and `json` values as the inline carry's serialization (compact, keys sorted),
-quoted. `markdownToAdf` emits `attrs`, `content` and `marks` keys only when non-empty; editor-normal
+quoted, `-0` spelled `-0`. `markdownToAdf` builds an `attrs`, `content` or `marks` key only where the
-ADF reads an empty attrs object, marks array or content array as the absent key (`docs/decisions.md`
+markdown spells one, an empty one through its reserved key (Attributes), so a document reads back
-§Equality is editor-normal) — the grammar's empty-`{attrs}` omission already collapses the two
+deep-equal (`docs/decisions.md` §Equality is deep). A node CommonMark spells takes the directive
-spellings.
+form to hold an empty key.
 
 Marks on a block node ride the reserved attribute key `marks` — the node's marks array as a
-`json` value: `!adf:layoutSection {marks="[{\"attrs\":{\"mode\":\"wide\"},\"type\":\"breakout\"}]"}`.
+`json` value, `marks=empty` where it is empty:
+`!adf:layoutSection {marks="[{\"attrs\":{\"mode\":\"wide\"},\"type\":\"breakout\"}]"}`.
 A section saying its body is inline takes at most one paragraph, whose inline content becomes
 the node's `content`; any other body is a named error, and an empty pair is a node holding none.
 
@@ -215,20 +235,23 @@ cannot — `localId` (string) on any of them, marks, and the values below — ta
 form.
 
 - `blockquote`, `bulletList`, `listItem` — containers, block body. Attributes: `localId` (string).
-- `codeBlock` — container, body one fenced code block whose info string is the language and whose
+- `codeBlock` — container, body one fenced code block per text node, each fence's info string the
-  content is the node's. Attributes: `hideLineNumbers` (boolean), `language` (string), `localId`
+  language and its content the node's text; a node holding no `content` key is one empty fence.
-  (string), `uniqueId` (string), `wrap` (boolean). A language no info string carries back — empty,
+  Attributes: `hideLineNumbers` (boolean), `language` (string), `localId` (string), `uniqueId`
-  the reserved `carry`, or holding a backtick, a backslash, a control character, edge whitespace or
+  (string), `wrap` (boolean). A language no info string carries back — empty, opening the reserved
-  an entity reference — rides the `language` attribute instead and the fence carries no info
+  `adf:`, or holding a backtick, a backslash, a control character, edge whitespace or an entity
-  string; writing it in the slot that rule leaves empty, or in both, is a named error. The body is
+  reference — rides the `language` attribute instead and the fences carry no info string, and so
-  one ordinary code block, and a fence's info string decodes escapes and entity references as any
+  does a language beside `content=empty`, which has no fence; writing it in the slot that rule
-  other does.
+  leaves empty, or in both, is a named error, and so are fences whose info strings differ and an
+  empty fence beside another. Each fence is an ordinary code block, and its info string decodes
+  escapes and entity references as any other does. A node holding a child no fence holds — any but
+  a text node carrying no marks, `attrs` or `content` — rides the block carry.
 - `heading` — container, inline body. Attributes: `level` (number), `localId` (string). `level` is
   the `#` count, so a heading carrying none, or one that is no whole number from 1 to 6, has no
   CommonMark spelling.
 - `orderedList` — container of `listItem`, block body. Attributes: `localId` (string), `order`
-  (number). `order` is the first marker, so a list carrying none, one that is no whole number
+  (number). `order` is the first marker, so a list carrying none, one that is `-0` or no whole
-  from 0, or one whose markers would run past 999999999, has no CommonMark spelling.
+  number from 0, or one whose markers would run past 999999999, has no CommonMark spelling.
 - `paragraph` — container, inline body. Attributes: `localId` (string).
 - `rule` — leaf. Attributes: `color` (string, `#rrggbb`), `localId` (string), `style` (`dashed`
   `dotted` `fade` `sketch` `solid`), `weight` (number, 1–3).
@@ -424,10 +447,9 @@ 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 text node carrying neither marks, attributes nor content — adjacent text
+parsing to anything but one text node carrying neither marks, attributes nor content is a named
-nodes with identical marks and no attributes merged first — is a named error, and so is a `text` key
+error, and so is a `text` key in `{attrs}`. An enclosing mark spelling does not reach into the slot.
-in `{attrs}`. An enclosing mark spelling does not reach into the slot. The rest take no content,
+The rest take no content, `!adf:text` included; content on a node that takes none is a named error.
-`!adf:text` included; content on a node that takes none is a named error.
 
 - `date` — Attributes: `localId` (string), `timestamp` (string, epoch milliseconds).
 - `emoji` — Attributes: `id` (string), `localId` (string), `shortName` (string, `:name:`), `text`
@@ -453,16 +475,27 @@ Shipped !adf:emoji[🎉]{shortName=":tada:"} on !adf:date{timestamp=175608000000
 CommonMark strips or refuses one — a block's inline content edges, either side of a line break, an
 em, strong or strike spelling's inner edges, a pipe cell's edges — is spelled `!adf: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;
+cells trim and pad. The emitter wraps the whitespace run alone and leaves the rest plain text, which
-`markdownToAdf` merges adjacent text nodes carrying identical marks and no attributes
+the spelled run joins on reading. Input reads that spelling alone: the value is one run of spaces
-(`docs/decisions.md` §Equality is editor-normal). Input reads that spelling alone: the value is one
+and tabs, or one run of newlines, and anything else — a mixed run, or text CommonMark carries
-run of spaces and tabs, or one run of newlines, and anything else — a mixed run, or text CommonMark
+plainly — is a named error.
-carries plainly — is a named error.
 
 ```
 !adf:text{text="  "}Two leading spaces held, and one text node split!adf:text{text="\n"}over two lines.
 ```
 
+**Adjacent text nodes.** CommonMark reads two adjacent text nodes back as one where neither is
+carried, neither holds `attrs` or an empty key, and their marks are identical, attributes included.
+The reserved leaf `!adf:textBreak{}` parts such a pair, inside every mark spelling the two share; a
+code span holds no directive, so it closes and reopens. It builds no node and reads only between
+two such nodes: elsewhere, or with `[content]` or `{attrs}`, it is a named error (`docs/decisions.md`
+§`!adf:textBreak{}` parts text CommonMark would join). A text node holding `attrs` or an empty key
+rides the inline carry.
+
+```
+Hello, !adf:textBreak{}world — **Hello, !adf:textBreak{}world** — `a`!adf:textBreak{}`b`
+```
+
 ## Marks
 
 An inline node's marks ride the spelling wrapped around them, never the block sections' reserved
@@ -490,20 +523,20 @@ the directive form, open to no literal reading, is a named error.
 A spelling adds its mark to every inline node it wraps, and nesting is the marks array in order,
 outermost first: `_!adf:underline[x]_` gives marks `[em, underline]`, `!adf:underline[_x_]` the
 reverse. `adfToMarkdown` nests in the order the array holds rather than sorting it —
-`docs/decisions.md` §Equality is editor-normal restores the array, not a set — and opens each
+`docs/decisions.md` §Equality is deep restores the array, not a set — and opens each spelling once
-spelling once over the longest run of adjacent inline nodes carrying an identical mark, attributes
+over the longest run of adjacent inline nodes carrying an identical mark, attributes included, at
-included, at that depth. A run breaks at every node the emitter carries, so no emitted carry sits
+that depth: `attrs: {}` differs from no `attrs`, and a directive spells it `{attrs=empty}`. A run
-inside a mark spelling.
+breaks at every node the emitter carries, so no emitted carry sits inside a mark spelling.
 
 An inline node whose marks no nesting spells — a mark type not listed here, an attrs key its
-spelling does not list, a value that is not the spelling's type, an attribute the spelling needs
+spelling does not list, a value that is not the spelling's type, an attribute the spelling needs and
-and the mark lacks, an order putting a code span outside another mark, `code` over anything but a
+the mark lacks, an empty `attrs` on a mark CommonMark spells, an order putting a code span outside
-text node or over text holding a newline, or a spelling CommonMark's flanking rules cannot open or
+another mark, `code` over anything but a text node or over text holding a newline, or a spelling
-close where the run sits (`un**-real**istic`), or one CommonMark's matching pairs elsewhere — the
+CommonMark's flanking rules cannot open or close where the run sits (`un**-real**istic`), or one
-intra-word `*` runs together with a neighbouring `**`, and the multiple-of-3 rule can leave the
+CommonMark's matching pairs elsewhere — the intra-word `*` runs together with a neighbouring `**`,
-merged run's pairing to another delimiter — rides the inline carry whole. An opaque carry inside a
+and the multiple-of-3 rule can leave the merged run's pairing to another delimiter — rides the
-mark spelling is a named error in input: the carry restores its node exactly, marks included
+inline carry whole. An opaque carry inside a mark spelling is a named error in input: the carry
-(`docs/decisions.md` §Unknown nodes ride the carry).
+restores its node exactly, marks included (`docs/decisions.md` §Unknown nodes ride the carry).
 
 ```
 !adf:textColor[**Overdue**]{color="#ae2e24"}, H!adf:subsup[2]{type=sub}O, !adf:underline[signed].

src/adf/document.ts

@@ -1,6 +1,7 @@
 import type { ConvertFault } from '../result.ts'
 import { isJsonValue, overNested, type JsonValue } from '../json-value.ts'
 import { largestNesting } from '../nesting.ts'
+import { serializeCanonicalJson } from '../canonical-json.ts'
 
 export type AdfAttributes = { [key: string]: JsonValue }
 
@@ -17,6 +18,8 @@ export type AdfNode = {
   type: string
 }
 
+export type EmptyKey = 'attrs' | 'content' | 'marks'
+
 export type AdfDocument = {
   content?: AdfNode[]
   type: 'doc'
@@ -48,11 +51,49 @@ export function attributeNestingMessage(key: string, type: string): string {
   return `the ${key} attribute of ${type} nests deeper than the ${largestNesting} levels an attribute carries`
 }
 
-export function carriesOnly(node: AdfNode, attributes: readonly string[]): boolean {
+export function holdsOnlyAttributes(node: AdfNode, attributes: readonly string[]): boolean {
-  if (nodeMarks(node).length > 0 || node.text !== undefined) return false
+  if (nodeMarks(node).length > 0 || node.text !== undefined || emptyKeys(node).length > 0) return false
   return holdsOnly(nodeAttrs(node), attributes)
 }
 
+export function emptyKeys(held: { attrs?: AdfAttributes; content?: AdfNode[]; marks?: AdfMark[] }): EmptyKey[] {
+  const keys: EmptyKey[] = []
+  if (held.attrs !== undefined && Object.keys(held.attrs).length === 0) keys.push('attrs')
+  if (held.content?.length === 0) keys.push('content')
+  if (held.marks?.length === 0) keys.push('marks')
+  return keys
+}
+
+// A text node holding no attrs or content key and no empty marks: a format spells it as text, where anything more rides a carry.
+export function isBareText(node: AdfNode): boolean {
+  return node.type === 'text' && node.attrs === undefined && node.content === undefined && node.marks?.length !== 0
+}
+
+export function isUnmarkedBareText(node: AdfNode): boolean {
+  return isBareText(node) && node.marks === undefined
+}
+
+export function identicalMark(left: AdfMark, right: AdfMark): boolean {
+  return marksKey([left]) === marksKey([right])
+}
+
+export function identicalMarks(left: readonly AdfMark[], right: readonly AdfMark[]): boolean {
+  return marksKey(left) === marksKey(right)
+}
+
+export function mergeAdjacentText(nodes: readonly AdfNode[], joins: (previous: AdfNode, node: AdfNode) => boolean): AdfNode[] {
+  const merged: AdfNode[] = []
+  for (const node of nodes) {
+    const previous = merged[merged.length - 1]
+    if (previous !== undefined && joins(previous, node)) {
+      merged[merged.length - 1] = { ...previous, text: `${previous.text ?? ''}${node.text ?? ''}` }
+      continue
+    }
+    merged.push(node)
+  }
+  return merged
+}
+
 // Depth is the walks' business, not the shape's: the guard waves a deep document through as blocks and marks do.
 export function isAdfDocument(value: unknown): value is AdfDocument {
   const fault = adfDocumentFault(value)
@@ -99,6 +140,13 @@ function isNodeArray(value: readonly unknown[]): value is readonly AdfNode[] {
   return true
 }
 
+function marksKey(marks: readonly AdfMark[]): string {
+  return serializeCanonicalJson(
+    marks.map((mark) => (mark.attrs === undefined ? [mark.type] : [mark.type, mark.attrs])),
+    'compact',
+  )
+}
+
 function nestingFault(nodes: readonly AdfNode[]): ConvertFault | undefined {
   const pending: AdfNode[] = [...nodes]
   while (pending.length > 0) {

src/canonical-json.ts

@@ -18,7 +18,7 @@ export function serializeCanonicalJson(value: JsonValue, spelling: JsonSpelling)
     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))
+    else text.push(Object.is(held, -0) ? '-0' : JSON.stringify(held))
   }
   return text.join('')
 }

src/conformance/adf-property.test.ts

@@ -5,10 +5,10 @@ import test from 'node:test'
 import type { AdfNode } from '../adf/document.ts'
 import { adfDocument, propertyRuns, propertyTimeout } from './property-harness.ts'
 import { adfToMarkdown } from '../markdown/emit/adf-to-markdown.ts'
-import { adfToPlainMarkdown, reduceToPlain } from '../markdown/emit/plain-reduction.ts'
+import { adfToPlainMarkdown, reduceToPlain } from '../markdown/plain/adf-to-plain-markdown.ts'
 import { directivePrefix } from '../markdown/directive-syntax.ts'
 import { markdownToAdf, plainMarkdownToAdf } from '../markdown/parse/markdown-to-adf.ts'
-import { toEditorNormal } from '../adf/editor-normal.ts'
+import { toEditorNormal } from '../markdown/plain/editor-normal.ts'
 
 const gateRuns = 1600
 const renamedPrefix = '!adg:'
@@ -41,7 +41,7 @@ test('a generated document refuses to emit, or its markdown reads back to it', {
       if (!emitted.ok) return
       const read = markdownToAdf(emitted.value)
       assert.ok(read.ok, read.ok ? '' : `${read.error.code}: ${read.error.message} — reading ${JSON.stringify(emitted.value)}`)
-      assert.deepEqual(toEditorNormal(read.value), document, `reading ${JSON.stringify(emitted.value)}`)
+      assert.deepEqual(read.value, document, `reading ${JSON.stringify(emitted.value)}`)
     }),
     propertyRuns(gateRuns),
   )
@@ -62,3 +62,12 @@ test('a generated document writes plain markdown refusing only what the guard re
     propertyRuns(gateRuns),
   )
 })
+
+test('a generated document writes the plain markdown its editor-normal form writes', { timeout: propertyTimeout }, () => {
+  fc.assert(
+    fc.property(adfDocument, (document) => {
+      assert.deepEqual(adfToPlainMarkdown(document), adfToPlainMarkdown(toEditorNormal(document)))
+    }),
+    propertyRuns(gateRuns),
+  )
+})

src/conformance/corpus.test.ts

@@ -9,7 +9,6 @@ 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')
@@ -97,7 +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}: ${result.error.message}`)
-      assert.deepEqual(toEditorNormal(result.value), expected)
+      assert.deepEqual(result.value, expected)
     })
   }
 }
@@ -125,12 +124,12 @@ for (const name of pairedNames(normalizationRoot, '.md', '.json')) {
     assert.ok(isAdfDocument(expected), `${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}: ${result.error.message}`)
-    assert.deepEqual(toEditorNormal(result.value), expected)
+    assert.deepEqual(result.value, expected)
     const emitted = adfToMarkdown(result.value)
     assert.ok(emitted.ok, emitted.ok ? '' : `${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(toEditorNormal(again.value), expected)
+    assert.deepEqual(again.value, expected)
   })
 }
 
@@ -146,7 +145,7 @@ for (const name of names(realPayloadsRoot, '.json')) {
     assert.ok(emitted.ok, emitted.ok ? '' : `${emitted.error.code}: ${emitted.error.message}`)
     const parsed = markdownToAdf(emitted.value)
     assert.ok(parsed.ok, parsed.ok ? '' : `${parsed.error.code}: ${parsed.error.message}`)
-    assert.deepEqual(toEditorNormal(parsed.value), payload)
+    assert.deepEqual(parsed.value, payload)
   })
 }
 

src/conformance/markdown-property.test.ts

@@ -31,7 +31,6 @@ import { markdownToAdf } from '../markdown/parse/markdown-to-adf.ts'
 import { nodeContent, nodeMarks } from '../adf/document.ts'
 import { serializeCanonicalJson } from '../canonical-json.ts'
 import { textDirectiveName } from '../markdown/text-directive.ts'
-import { toEditorNormal } from '../adf/editor-normal.ts'
 import { vocabularyPairs } from '../adf/attribute-vocabulary.ts'
 
 type Choice = { arbitrary: Arbitrary<string>; hostile?: true; weight: number }
@@ -433,7 +432,7 @@ test('generated markdown refuses, or what it parses to refuses to emit, or its s
       if (holdsDirectiveShape(parsed.value)) directiveShaped += 1
       const read = markdownToAdf(emitted.value)
       assert.ok(read.ok, read.ok ? '' : `${read.error.code}: ${read.error.message} — reading ${JSON.stringify(emitted.value)}`)
-      assert.deepEqual(toEditorNormal(read.value), toEditorNormal(parsed.value), `reading ${JSON.stringify(emitted.value)}`)
+      assert.deepEqual(read.value, parsed.value, `reading ${JSON.stringify(emitted.value)}`)
       const respelled = adfToMarkdown(read.value)
       assert.ok(respelled.ok, respelled.ok ? '' : `${respelled.error.code}: ${respelled.error.message} — spelling ${JSON.stringify(emitted.value)} again`)
       assert.equal(respelled.value, emitted.value)

src/conformance/property-harness.ts

@@ -2,16 +2,17 @@ import assert from 'node:assert/strict'
 import { env } from 'node:process'
 import fc from 'fast-check'
 
-import type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from '../adf/document.ts'
+import type { AdfAttributes, AdfDocument, AdfMark, AdfNode, EmptyKey } from '../adf/document.ts'
 import type { Arbitrary } from 'fast-check'
 import type { AttributeKind, AttributeVocabulary } from '../adf/attribute-vocabulary.ts'
 import type { JsonValue } from '../json-value.ts'
 import { blockArgument } from '../markdown/block-directive.ts'
 import { blockNodes } from '../adf/block-nodes.ts'
 import { directivePrefix } from '../markdown/directive-syntax.ts'
+import { emptyKeys, mergeAdjacentText } from '../adf/document.ts'
 import { inlineNodes } from '../adf/inline-nodes.ts'
+import { joinsWhenRead } from '../markdown/adjacent-text.ts'
 import { markAttributes } from '../adf/mark-attributes.ts'
-import { toEditorNormal } from '../adf/editor-normal.ts'
 
 type Positions = { block: AdfNode; inline: AdfNode }
 
@@ -36,7 +37,11 @@ export function textOf(minLength: number): Arbitrary<string> {
 
 const text = textOf(1)
 const unknownType = fc.oneof(fc.stringMatching(/^[a-z][A-Za-z0-9]{0,7}$/), text).filter((type) => !spelledTypes.has(type))
-const numberValue = fc.oneof({ arbitrary: fc.integer({ max: 10, min: -1 }), weight: 3 }, { arbitrary: fc.double({ noDefaultInfinity: true, noNaN: true }), weight: 1 })
+const numberValue = fc.oneof(
+  { arbitrary: fc.integer({ max: 10, min: -1 }), weight: 6 },
+  { arbitrary: fc.double({ noDefaultInfinity: true, noNaN: true }), weight: 2 },
+  { arbitrary: fc.constant(-0), weight: 1 },
+)
 
 // V8's JSON.parse returns a wrong key after parsing a key holding an escaped backslash (https://issues.chromium.org/issues/521080746); Bun is unaffected.
 const keyPiece = fc
@@ -73,19 +78,35 @@ function heldAttributes(held: Readonly<Record<string, JsonValue | undefined>>):
   return attrs
 }
 
+// An empty attrs, content or marks key, and adjacent text CommonMark would read back as one, stay occasional: each takes a spelling outside CommonMark.
+// The copy gives fast-check's null-prototype records the prototype a parsed node has.
+function occasionallyEmpty<T extends AdfMark | AdfNode>(arbitrary: Arbitrary<T>): Arbitrary<T> {
+  return fc.tuple(arbitrary, fc.nat({ max: 9 })).map(([held, roll]) => (roll === 0 ? { ...held } : withoutEmptyKeys(held)))
+}
+
+function withoutEmptyKeys<T extends AdfMark | AdfNode>(held: T): T {
+  const kept: Partial<Record<EmptyKey, unknown>> & T = { ...held }
+  for (const key of emptyKeys(held)) delete kept[key]
+  return kept
+}
+
+function occasionallyApart(arbitrary: Arbitrary<AdfNode[]>): Arbitrary<AdfNode[]> {
+  return fc.tuple(arbitrary, fc.nat({ max: 5 })).map(([nodes, roll]) => (roll === 0 ? nodes : mergeAdjacentText(nodes, joinsWhenRead)))
+}
+
 function pipeTable({ body, header }: { body: AdfNode[][]; header: AdfNode[] }): AdfNode {
   const rows = [header, ...body.map((cells) => header.map((_, index) => cells[index] ?? emptyCell))]
   return { content: rows.map((content): AdfNode => ({ content, type: 'tableRow' })), type: 'table' }
 }
 
-const mark: Arbitrary<AdfMark> = fc.oneof(
+const mark: Arbitrary<AdfMark> = occasionallyEmpty(fc.oneof(
   { arbitrary: fc.oneof(...Object.entries(markAttributes).map(([type, vocabulary]) => attributes(vocabulary).map((attrs) => ({ attrs, type })))), weight: 9 },
   { arbitrary: attributes({ color: 'string' }).map((attrs) => ({ attrs, type: 'backgroundColor' })), weight: 2 },
   { arbitrary: fc.record({ attrs: fc.dictionary(jsonKey, jsonValue, { maxKeys: 2, noNullPrototype: true }), type: unknownType }), weight: 1 },
-)
+))
 const marks = fc.uniqueArray(mark, { maxLength: 3, selector: (held) => held.type })
 
-const textNode = fc.record({ marks, text }).map((held): AdfNode => ({ ...held, type: 'text' }))
+const textNode = occasionallyEmpty(fc.record({ marks, text }).map((held): AdfNode => ({ ...held, type: 'text' })))
 
 const backtickRunNode = fc
   .record({ marks: fc.oneof(fc.constant<AdfMark[]>([]), fc.constant<AdfMark[]>([{ type: 'code' }]), marks), text: fc.string({ maxLength: 6, minLength: 1, unit: fc.constantFrom('`', '``', ' ', 'a') }) })
@@ -96,7 +117,7 @@ const autolinkTextNode = fc
   .map(({ href, marks: held }): AdfNode => ({ marks: [...held.filter((outer) => outer.type !== 'link'), { attrs: { href }, type: 'link' }], text: href, type: 'text' }))
 
 const inlineArbitraries = Object.entries(inlineNodes).map(([type, model]) =>
-  fc.record({ attrs: attributes(model.attributes), marks }).map((held): AdfNode => ({ ...held, type })),
+  occasionallyEmpty(fc.record({ attrs: attributes(model.attributes), marks }).map((held): AdfNode => ({ ...held, type }))),
 )
 
 function weighted(arbitraries: readonly Arbitrary<AdfNode>[], weight: number): { arbitrary: Arbitrary<AdfNode>; weight: number }[] {
@@ -105,10 +126,10 @@ function weighted(arbitraries: readonly Arbitrary<AdfNode>[], weight: number): {
 
 const positions = fc.letrec<Positions>((tie) => {
   const blockContent = fc.array(tie('block'), { depthIdentifier, maxLength: 3 })
-  const inlineContent = fc.array(tie('inline'), { depthIdentifier, maxLength: 4 })
+  const inlineContent = occasionallyApart(fc.array(tie('inline'), { depthIdentifier, maxLength: 4 }))
   const contentByModel = {
     block: blockContent,
-    code: fc.array(text.map((held): AdfNode => ({ text: held, type: 'text' })), { maxLength: 2 }),
+    code: occasionallyApart(fc.array(text.map((held): AdfNode => ({ text: held, type: 'text' })), { maxLength: 2 })),
     inline: inlineContent,
     none: fc.constant<AdfNode[]>([]),
   }
@@ -116,35 +137,40 @@ const positions = fc.letrec<Positions>((tie) => {
   const blockArbitraries = Object.entries(blockNodes).map(([type, model]) => {
     const argument = blockArgument(type)
     const vocabulary: AttributeVocabulary = argument === undefined ? model.attributes : { ...model.attributes, [argument]: 'string' }
-    const node = fc.record({ attrs: attributes(vocabulary), content: contentByModel[model.contentModel], marks: blockMarks }).map((held): AdfNode => ({ ...held, type }))
+    const node = occasionallyEmpty(fc.record({ attrs: attributes(vocabulary), content: contentByModel[model.contentModel], marks: blockMarks }).map((held): AdfNode => ({ ...held, type })))
     return { leaf: model.contentModel === 'code' || model.contentModel === 'none', node }
   })
-  const unknownNode = fc
+  const unknownNode = occasionallyEmpty(
-    .record({ attrs: fc.dictionary(jsonKey, jsonValue, { maxKeys: 2, noNullPrototype: true }), content: fc.array(tie('inline'), { depthIdentifier, maxLength: 2 }), marks, type: unknownType })
+    fc.record({ attrs: fc.dictionary(jsonKey, jsonValue, { maxKeys: 2, noNullPrototype: true }), content: fc.array(tie('inline'), { depthIdentifier, maxLength: 2 }), marks, type: unknownType }),
-    .map((held): AdfNode => held)
+  )
   const leafBlocks = blockArbitraries.filter((entry) => entry.leaf).map((entry) => entry.node)
   const containerBlocks = blockArbitraries.filter((entry) => !entry.leaf).map((entry) => entry.node)
   const misplacedWeight = 7
-  const paragraph = fc.oneof({ arbitrary: inlineContent, weight: 3 }, { arbitrary: fc.array(backtickRunNode, { maxLength: 4, minLength: 2 }), weight: 1 }).map((content): AdfNode => ({ content, type: 'paragraph' }))
+  const paragraph = occasionallyEmpty(
+    fc.oneof({ arbitrary: inlineContent, weight: 3 }, { arbitrary: occasionallyApart(fc.array(backtickRunNode, { maxLength: 4, minLength: 2 })), weight: 1 }).map((content): AdfNode => ({ content, type: 'paragraph' })),
+  )
   const cell = (type: string) => paragraph.map((held): AdfNode => ({ content: [held], type }))
   const listItems = fc.array(
-    blockContent.map((content): AdfNode => ({ content, type: 'listItem' })),
+    occasionallyEmpty(blockContent.map((content): AdfNode => ({ content, type: 'listItem' }))),
     { depthIdentifier, maxLength: 3, minLength: 1 },
   )
   const flatCommonMarkShapes = [
-    fc.record({ content: inlineContent, level: fc.integer({ max: 6, min: 1 }) }).map(({ content, level }): AdfNode => ({ attrs: { level }, content, type: 'heading' })),
+    occasionallyEmpty(fc.record({ content: inlineContent, level: fc.integer({ max: 6, min: 1 }) }).map(({ content, level }): AdfNode => ({ attrs: { level }, content, type: 'heading' }))),
     paragraph,
     fc.record({ body: fc.array(fc.array(cell('tableCell'), { maxLength: 3 }), { maxLength: 2 }), header: fc.array(cell('tableHeader'), { maxLength: 3, minLength: 1 }) }).map(pipeTable),
   ]
   const task = (type: string, content: Arbitrary<AdfNode[]>) =>
-    fc.record({ content, state: fc.constantFrom('DONE', 'TODO') }).map(({ content: held, state }): AdfNode => ({ attrs: { state }, content: held, type }))
+    occasionallyEmpty(fc.record({ content, state: fc.constantFrom('DONE', 'TODO') }).map(({ content: held, state }): AdfNode => ({ attrs: { state }, content: held, type })))
   const taskItem = fc.oneof({ arbitrary: task('taskItem', inlineContent), weight: 3 }, { arbitrary: task('blockTaskItem', blockContent), weight: 1 })
   const nestingCommonMarkShapes = [
-    blockContent.map((content): AdfNode => ({ content, type: 'blockquote' })),
+    occasionallyEmpty(blockContent.map((content): AdfNode => ({ content, type: 'blockquote' }))),
     fc.array(fc.oneof({ arbitrary: taskItem, weight: 3 }, { arbitrary: tie('block'), weight: 1 }), { depthIdentifier, maxLength: 3, minLength: 1 }).map((content): AdfNode => ({ content, type: 'taskList' })),
     listItems.map((content): AdfNode => ({ content, type: 'bulletList' })),
     fc
-      .record({ content: listItems, order: fc.oneof({ arbitrary: fc.integer({ max: 3, min: 0 }), weight: 4 }, { arbitrary: fc.integer({ max: 999999999, min: 0 }), weight: 1 }) })
+      .record({
+        content: listItems,
+        order: fc.oneof({ arbitrary: fc.integer({ max: 3, min: 0 }), weight: 8 }, { arbitrary: fc.integer({ max: 999999999, min: 0 }), weight: 2 }, { arbitrary: fc.constant(-0), weight: 1 }),
+      })
       .map(({ content, order }): AdfNode => ({ attrs: { order }, content, type: 'orderedList' })),
   ]
   const flatBlocks = [...weighted(leafBlocks, 2), ...weighted(flatCommonMarkShapes, flatCommonMarkShapeWeight)]
@@ -167,7 +193,11 @@ const positions = fc.letrec<Positions>((tie) => {
   }
 })
 
-export const adfDocument = fc.array(positions.block, { depthIdentifier, maxLength: 4, minLength: 1 }).map((content): AdfDocument => toEditorNormal({ content, type: 'doc', version: 1 }))
+export const adfDocument = fc.oneof(
+  { arbitrary: fc.array(positions.block, { depthIdentifier, maxLength: 4, minLength: 1 }).map((content): AdfDocument => ({ content, type: 'doc', version: 1 })), weight: 30 },
+  { arbitrary: fc.constant<AdfDocument>({ content: [], type: 'doc', version: 1 }), weight: 1 },
+  { arbitrary: fc.constant<AdfDocument>({ type: 'doc', version: 1 }), weight: 1 },
+)
 
 export function propertyRuns(gateRuns: number): { gate: boolean; numRuns: number; seed?: number } {
   const deepRuns = env[deepRunsVariable]

src/index.ts

@@ -3,6 +3,6 @@ export type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from './adf/documen
 export type { ConvertError, ConvertErrorCode, ConvertErrorPath, ParseError, Result, SourcePosition } from './result.ts'
 export type { JsonValue } from './json-value.ts'
 export { adfToMarkdown } from './markdown/emit/adf-to-markdown.ts'
-export { adfToPlainMarkdown } from './markdown/emit/plain-reduction.ts'
+export { adfToPlainMarkdown } from './markdown/plain/adf-to-plain-markdown.ts'
 export { isAdfDocument } from './adf/document.ts'
 export { markdownToAdf, plainMarkdownToAdf } from './markdown/parse/markdown-to-adf.ts'

src/markdown/adjacent-text.ts

@@ -0,0 +1,12 @@
+import type { AdfNode } from '../adf/document.ts'
+import { identicalMarks, isBareText, nodeMarks } from '../adf/document.ts'
+import { spellInlineLeafDirective } from './directive-syntax.ts'
+
+export const textBreakName = 'textBreak'
+
+export const textBreakSpelling = spellInlineLeafDirective(textBreakName, '')
+
+// The lossless reader's rule: CommonMark reads the pair back as one text run (spec/flavour.md, Inline nodes).
+export function joinsWhenRead(previous: AdfNode, node: AdfNode): boolean {
+  return isBareText(previous) && isBareText(node) && identicalMarks(nodeMarks(previous), nodeMarks(node))
+}

src/markdown/block-directive.ts

@@ -2,9 +2,9 @@ import type { AdfMark } from '../adf/document.ts'
 import type { BlockType } from '../adf/block-nodes.ts'
 import type { JsonValue } from '../json-value.ts'
 import { blockNodeModel } from '../adf/block-nodes.ts'
-import { isAdfMark, nodeAttrs } from '../adf/document.ts'
+import { isAdfMark } from '../adf/document.ts'
 import { serializeCanonicalJson } from '../canonical-json.ts'
-import { spellDirectiveOpener } from './directive-syntax.ts'
+import { spellAttributes, spellDirectiveOpener } from './directive-syntax.ts'
 
 const argumentByType = new Map(
   Object.entries({
@@ -14,6 +14,13 @@ const argumentByType = new Map(
   } satisfies Partial<Record<BlockType, string>>),
 )
 
+export const documentName = 'doc'
+
+// spec/flavour.md, Directives: a document holding no content key, which the empty string cannot spell.
+export const documentAttribute = { key: 'content', value: 'none' }
+
+export const documentSpelling = spellDirectiveOpener(documentName, undefined, spellAttributes([[documentAttribute.key, documentAttribute.value]]))
+
 export const listBreakName = 'listBreak'
 
 export const listBreakSpelling = spellDirectiveOpener(listBreakName, undefined, '')
@@ -25,17 +32,14 @@ export function blockArgument(type: string): string | undefined {
 }
 
 export function blockDirectiveForm(name: string): 'container' | 'leaf' | undefined {
-  if (name === listBreakName) return 'leaf'
+  if (name === listBreakName || name === documentName) return 'leaf'
   const model = blockNodeModel(name)
   if (model === undefined) return undefined
   return model.contentModel === 'none' ? 'leaf' : 'container'
 }
 
 export function markValues(marks: readonly AdfMark[]): JsonValue {
-  return marks.map((mark) => {
+  return marks.map((mark) => (mark.attrs === undefined ? { type: mark.type } : { attrs: mark.attrs, type: mark.type }))
-    const attrs = nodeAttrs(mark)
-    return Object.keys(attrs).length === 0 ? { type: mark.type } : { attrs, type: mark.type }
-  })
 }
 
 export function readMarkValues(value: JsonValue): AdfMark[] | undefined {

src/markdown/code-language.ts

@@ -1,14 +1,12 @@
 import type { JsonValue } from '../json-value.ts'
-import { carryName } from './opaque-carry.ts'
+import { carryFenceType } from './opaque-carry.ts'
-import { holdsControlCharacter } from './commonmark/grammar.ts'
+import { infoStringCarries } from './commonmark/grammar.ts'
-import { holdsEntityReference } from './commonmark/entity-references.ts'
 
 export type LanguageSlot = { info: string; kind: 'fence' } | { kind: 'attribute' } | { kind: 'none' }
 
 // spec/flavour.md, The CommonMark blocks: the one slot a codeBlock's language rides.
 export function languageSlot(language: JsonValue | undefined): LanguageSlot {
   if (language === undefined) return { kind: 'none' }
-  if (typeof language !== 'string' || language === '' || language === carryName) return { kind: 'attribute' }
+  if (typeof language !== 'string' || carryFenceType(language) !== undefined || !infoStringCarries(language)) return { kind: 'attribute' }
-  if (/[`\\]/.test(language) || holdsControlCharacter(language) || language !== language.trim() || holdsEntityReference(language)) return { kind: 'attribute' }
   return { info: language, kind: 'fence' }
 }

src/markdown/commonmark/grammar.ts

@@ -1,4 +1,4 @@
-import { readEntityReference, replacementCharacter } from './entity-references.ts'
+import { holdsEntityReference, readEntityReference, replacementCharacter } from './entity-references.ts'
 
 export type LinePosition = 'first' | 'later'
 
@@ -133,6 +133,11 @@ export function holdsControlCharacter(text: string): boolean {
   return controlCharacter.test(text)
 }
 
+// What a backtick fence's info string reads back verbatim: escapes and entity references decode, and the edges trim.
+export function infoStringCarries(text: string): boolean {
+  return text !== '' && !/[`\\]/.test(text) && !holdsControlCharacter(text) && text === text.trim() && !holdsEntityReference(text)
+}
+
 export function holdsNullCharacter(text: string): boolean {
   return nullCharacter.test(text)
 }

src/markdown/directive-syntax.ts

@@ -139,7 +139,7 @@ export function spellStringAttribute(text: string): string {
 export function spellAttributeValue(value: VocabularyValue): string {
   if (value.kind === 'boolean') return `${value.value}`
   if (value.kind === 'json') return spellJsonAttribute(value.value)
-  if (value.kind === 'number') return spellStringAttribute(JSON.stringify(value.value))
+  if (value.kind === 'number') return spellStringAttribute(serializeCanonicalJson(value.value, 'compact'))
   return spellStringAttribute(value.value)
 }
 

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

@@ -6,14 +6,13 @@ 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 }
 }
 
 function paragraph(...content: AdfNode[]): AdfNode {
-  return { content, type: 'paragraph' }
+  return content.length === 0 ? { type: 'paragraph' } : { content, type: 'paragraph' }
 }
 
 function code(result: Result<string>): string {
@@ -168,21 +167,24 @@ test('parts two adjacent lists of the same kind, the marker spelling being what
   const nested: AdfNode = { content: [{ content: [list, list], type: 'listItem' }], type: 'bulletList' }
   assert.equal(markdown(adfToMarkdown(document(nested))), '- - x\n\n  !adf:listBreak\n\n  - x\n')
   const carried: AdfNode = { ...list, attrs: { unknown: 'x' } }
-  assert.ok(markdown(adfToMarkdown(document(carried, carried))).includes('```\n\n```carry\n'))
+  assert.ok(markdown(adfToMarkdown(document(carried, carried))).includes('```\n\n```adf:bulletList\n'))
   assert.ok(markdown(adfToMarkdown(document(carried, list))).endsWith('```\n\n- x\n'))
-  assert.ok(markdown(adfToMarkdown(document(list, carried))).startsWith('- x\n\n```carry\n'))
+  assert.ok(markdown(adfToMarkdown(document(list, carried))).startsWith('- x\n\n```adf:bulletList\n'))
 })
 
-test('carries a node type no section spells', () => {
+test('carries a node type no section spells, the fence naming the type wherever an info string carries it', () => {
-  assert.equal(markdown(adfToMarkdown(document({ type: 'blockCard' }))), '```carry\n{\n  "type": "blockCard"\n}\n```\n')
+  assert.equal(markdown(adfToMarkdown(document({ type: 'blockCard' }))), '```adf:blockCard\n{}\n```\n')
-  assert.equal(markdown(adfToMarkdown(document({ type: 'toString' }))), '```carry\n{\n  "type": "toString"\n}\n```\n')
+  assert.equal(markdown(adfToMarkdown(document({ type: 'toString' }))), '```adf:toString\n{}\n```\n')
   assert.equal(markdown(adfToMarkdown(document(paragraph({ type: 'blockCard' })))), '!adf:carry{json="{\\"type\\":\\"blockCard\\"}"}\n')
-  assert.equal(markdown(adfToMarkdown(document({ text: 'x', type: 'text' }))), '```carry\n{\n  "text": "x",\n  "type": "text"\n}\n```\n')
+  assert.equal(markdown(adfToMarkdown(document({ text: 'x', type: 'text' }))), '```adf:text\n{\n  "text": "x"\n}\n```\n')
-  assert.equal(markdown(adfToMarkdown(document({ type: 'hardBreak' }))), '```carry\n{\n  "type": "hardBreak"\n}\n```\n')
+  assert.equal(markdown(adfToMarkdown(document({ type: 'hardBreak' }))), '```adf:hardBreak\n{}\n```\n')
+  assert.equal(markdown(adfToMarkdown(document({ type: 'a&amp;b' }))), '```adf:\n{\n  "type": "a&amp;b"\n}\n```\n')
+  assert.equal(markdown(adfToMarkdown(document({ type: 'a\\b' }))), '```adf:\n{\n  "type": "a\\\\b"\n}\n```\n')
 })
 
-test('spells the code block whose language is the reserved info string', () => {
+test('spells the code block whose language opens with the reserved info string prefix', () => {
-  assert.equal(markdown(adfToMarkdown(document({ attrs: { language: 'carry' }, type: 'codeBlock' }))), '!adf:codeBlock {language=carry}\n```\n```\n!adf:/codeBlock\n')
+  assert.equal(markdown(adfToMarkdown(document({ attrs: { language: 'adf:x' }, type: 'codeBlock' }))), '!adf:codeBlock {language="adf:x"}\n```\n```\n!adf:/codeBlock\n')
+  assert.equal(markdown(adfToMarkdown(document({ attrs: { language: 'carry' }, type: 'codeBlock' }))), '```carry\n```\n')
   assert.equal(markdown(adfToMarkdown(document({ attrs: { language: 'adf' }, type: 'codeBlock' }))), '```adf\n```\n')
 })
 
@@ -208,21 +210,17 @@ test('refuses a carried node nested deeper than the levels its position leaves',
   assert.equal(code(adfToMarkdown(document(quoted))), 'unsupported-nesting-depth')
 })
 
-test('refuses a node whose content model the canonical form cannot emit', () => {
+test('carries a code block holding a node no fence holds', () => {
-  assert.equal(
+  assert.equal(markdown(adfToMarkdown(document({ content: [paragraph()], type: 'codeBlock' }))), '```adf:codeBlock\n{\n  "content": [\n    {\n      "type": "paragraph"\n    }\n  ]\n}\n```\n')
-    markdown(adfToMarkdown(document({ content: [paragraph()], type: 'codeBlock' }))),
+  for (const child of [{ attrs: {}, text: 'x', type: 'text' }, { content: [], text: 'x', type: 'text' }, { marks: [], text: 'x', type: 'text' }, { content: [{ text: 'lost', type: 'text' }], text: 'x', type: 'text' }]) {
-    'unsupported-node-shape: a codeBlock holds plain text nodes only: this paragraph node is not one',
+    assert.ok(markdown(adfToMarkdown(document({ content: [child], type: 'codeBlock' }))).startsWith('```adf:codeBlock\n'), JSON.stringify(child))
-  )
+  }
-  assert.equal(
-    markdown(adfToMarkdown(document({ content: [{ content: [{ text: 'lost', type: 'text' }], text: 'x', type: 'text' }], type: 'codeBlock' }))),
-    'unsupported-node-shape: a codeBlock holds plain text nodes only: this text node is not one',
-  )
 })
 
 test('spells a list its own content shape cannot hold as a directive', () => {
   assert.equal(markdown(adfToMarkdown(document({ content: [paragraph()], type: 'bulletList' }))), '!adf:bulletList\n!adf:paragraph\n!adf:/paragraph\n!adf:/bulletList\n')
   assert.equal(markdown(adfToMarkdown(document({ type: 'bulletList' }))), '!adf:bulletList\n!adf:/bulletList\n')
-  assert.equal(markdown(adfToMarkdown(document({ attrs: { order: 2 }, content: [], type: 'orderedList' }))), '!adf:orderedList {order=2}\n!adf:/orderedList\n')
+  assert.equal(markdown(adfToMarkdown(document({ attrs: { order: 2 }, content: [], type: 'orderedList' }))), '!adf:orderedList {content=empty order=2}\n!adf:/orderedList\n')
 })
 
 test('spells an ordered list no marker fits as a directive', () => {
@@ -334,7 +332,7 @@ test('refuses a node carrying one mark type twice', () => {
 })
 
 test('parts a nested list the tight spelling would swallow from the block above it', () => {
-  const item = (...content: AdfNode[]): AdfNode => ({ content, type: 'listItem' })
+  const item = (...content: AdfNode[]): AdfNode => (content.length === 0 ? { type: 'listItem' } : { content, type: 'listItem' })
   const text = (value: string): AdfNode => ({ content: [{ text: value, type: 'text' }], type: 'paragraph' })
   const outer = (...content: AdfNode[]): AdfDocument => document({ content: [item(...content)], type: 'bulletList' })
   const ordered: AdfNode = { attrs: { order: 2 }, content: [item(text('b'))], type: 'orderedList' }
@@ -345,7 +343,7 @@ test('parts a nested list the tight spelling would swallow from the block above
   const list: AdfNode = { content: [item(text('b'))], type: 'bulletList' }
   const panel: AdfNode = { attrs: { panelType: 'info' }, content: [text('p')], type: 'panel' }
   assert.equal(markdown(adfToMarkdown(outer(panel, list))), '- !adf:panel info\n  p\n  !adf:/panel\n\n  - b\n')
-  assert.ok(markdown(adfToMarkdown(outer(text('a'), { ...list, attrs: { unknown: 'x' } }))).startsWith('- a\n\n  ```carry\n'))
+  assert.ok(markdown(adfToMarkdown(outer(text('a'), { ...list, attrs: { unknown: 'x' } }))).startsWith('- a\n\n  ```adf:bulletList\n'))
 })
 
 test('refuses marks and attributes nested deeper than the emitter carries', () => {
@@ -372,7 +370,7 @@ test('refuses marks and attributes nested deeper than the emitter carries', () =
     assert.ok(spelled.ok, spelled.ok ? '' : spelled.error.message)
     const read = markdownToAdf(spelled.value)
     assert.ok(read.ok, read.ok ? '' : read.error.message)
-    assert.deepEqual(toEditorNormal(read.value), document(node))
+    assert.deepEqual(read.value, document(node))
   }
 
   assert.equal(markdown(adfToMarkdown(document(paragraph({ marks: [{ attrs, type: 'em' }], text: 'x', type: 'text' })))), deeper('depth', 'em'))
@@ -442,7 +440,7 @@ test('escapes a hyphen underline a hard break would expose', () => {
 })
 
 test('spells a list item whose marker completes a thematic break as a directive', () => {
-  const item = (...content: AdfNode[]): AdfNode => ({ content, type: 'listItem' })
+  const item = (...content: AdfNode[]): AdfNode => (content.length === 0 ? { type: 'listItem' } : { content, type: 'listItem' })
   assert.equal(markdown(adfToMarkdown(document({ content: [item({ type: 'rule' })], type: 'bulletList' }))), '!adf:bulletList\n!adf:listItem\n---\n!adf:/listItem\n!adf:/bulletList\n')
   const nested: AdfNode = { content: [item({ content: [item()], type: 'bulletList' })], type: 'bulletList' }
   assert.equal(markdown(adfToMarkdown(document(nested))), '- -\n')
@@ -469,10 +467,7 @@ test('refuses the characters CommonMark rewrites', () => {
   )
   assert.equal(code(adfToMarkdown(document(paragraph({ text: 'a\u0000b', type: 'text' })))), 'unspellable-character')
   assert.equal(code(adfToMarkdown(document({ content: [{ text: 'a\u0000b', type: 'text' }], type: 'codeBlock' }))), 'unspellable-character')
-  assert.equal(
+  assert.equal(markdown(adfToMarkdown(document({ content: [{ text: '', type: 'text' }], type: 'codeBlock' }))), 'unsupported-node-shape: a text node holds text: this one has none')
-    markdown(adfToMarkdown(document({ content: [{ text: '', type: 'text' }], type: 'codeBlock' }))),
-    'unsupported-node-shape: a codeBlock holds plain text nodes only: this text node is not one',
-  )
 })
 
 test('refuses a text node the spelling would empty out', () => {
@@ -501,11 +496,11 @@ test('pads a code span whose edges CommonMark would strip', () => {
   assert.equal(markdown(adfToMarkdown(document(paragraph({ marks: [{ type: 'code' }], text: ' \t ', type: 'text' })))), '`  \t  `\n')
 })
 
-test('spells one code span over a run of code-marked nodes', () => {
+test('spells a code span per code-marked node, parted by the text break', () => {
   const code_ = { type: 'code' }
   assert.equal(
     markdown(adfToMarkdown(document(paragraph({ marks: [code_], text: 'a', type: 'text' }, { marks: [code_], text: 'b', type: 'text' })))),
-    '`ab`\n',
+    '`a`!adf:textBreak{}`b`\n',
   )
 })
 
@@ -545,7 +540,7 @@ test('emits an empty list item without trailing whitespace', () => {
 test('spells a block directive as its node type, arg and attributes', () => {
   const panel = (attrs: AdfAttributes): AdfDocument => document({ attrs, content: [paragraph({ text: 'x', type: 'text' })], type: 'panel' })
   assert.equal(markdown(adfToMarkdown(panel({ panelType: 'warning' }))), '!adf:panel warning\nx\n!adf:/panel\n')
-  assert.equal(markdown(adfToMarkdown(panel({}))), '!adf:panel\nx\n!adf:/panel\n')
+  assert.equal(markdown(adfToMarkdown(panel({}))), '!adf:panel {attrs=empty}\nx\n!adf:/panel\n')
   assert.equal(markdown(adfToMarkdown(document({ content: [{ text: 'x', type: 'text' }], type: 'caption' }))), '!adf:caption\nx\n!adf:/caption\n')
   assert.equal(markdown(adfToMarkdown(document({ type: 'caption' }))), '!adf:caption\n!adf:/caption\n')
   assert.equal(markdown(adfToMarkdown(document({ attrs: { localId: 'a' }, type: 'syncBlock' }))), '!adf:syncBlock {localId=a}\n')
@@ -553,20 +548,20 @@ test('spells a block directive as its node type, arg and attributes', () => {
 
 test('carries a directive attribute no section spells', () => {
   const carried = (node: AdfNode): string => markdown(adfToMarkdown(document(node)))
-  assert.equal(carried({ attrs: { rounded: true }, type: 'panel' }), '```carry\n{\n  "attrs": {\n    "rounded": true\n  },\n  "type": "panel"\n}\n```\n')
+  assert.equal(carried({ attrs: { rounded: true }, type: 'panel' }), '```adf:panel\n{\n  "attrs": {\n    "rounded": true\n  }\n}\n```\n')
-  assert.equal(carried({ attrs: { toString: 'x' }, type: 'panel' }), '```carry\n{\n  "attrs": {\n    "toString": "x"\n  },\n  "type": "panel"\n}\n```\n')
+  assert.equal(carried({ attrs: { toString: 'x' }, type: 'panel' }), '```adf:panel\n{\n  "attrs": {\n    "toString": "x"\n  }\n}\n```\n')
-  assert.equal(carried({ attrs: { localId: 4 }, type: 'panel' }), '```carry\n{\n  "attrs": {\n    "localId": 4\n  },\n  "type": "panel"\n}\n```\n')
+  assert.equal(carried({ attrs: { localId: 4 }, type: 'panel' }), '```adf:panel\n{\n  "attrs": {\n    "localId": 4\n  }\n}\n```\n')
   assert.equal(
     carried({ attrs: { width: '50' }, type: 'layoutColumn' }),
-    '```carry\n{\n  "attrs": {\n    "width": "50"\n  },\n  "type": "layoutColumn"\n}\n```\n',
+    '```adf:layoutColumn\n{\n  "attrs": {\n    "width": "50"\n  }\n}\n```\n',
   )
   assert.equal(
     carried({ attrs: { isNumberColumnEnabled: 'true' }, type: 'table' }),
-    '```carry\n{\n  "attrs": {\n    "isNumberColumnEnabled": "true"\n  },\n  "type": "table"\n}\n```\n',
+    '```adf:table\n{\n  "attrs": {\n    "isNumberColumnEnabled": "true"\n  }\n}\n```\n',
   )
   assert.equal(
     carried({ content: [{ attrs: { alt: 4 }, type: 'media' }], type: 'mediaGroup' }),
-    '!adf:mediaGroup\n```carry\n{\n  "attrs": {\n    "alt": 4\n  },\n  "type": "media"\n}\n```\n!adf:/mediaGroup\n',
+    '!adf:mediaGroup\n```adf:media\n{\n  "attrs": {\n    "alt": 4\n  }\n}\n```\n!adf:/mediaGroup\n',
   )
 })
 
@@ -574,15 +569,16 @@ test('carries an arg slot value no bare token spells', () => {
   const carried = (node: AdfNode): string => markdown(adfToMarkdown(document(node)))
   assert.equal(
     carried({ attrs: { panelType: 'extra info' }, type: 'panel' }),
-    '```carry\n{\n  "attrs": {\n    "panelType": "extra info"\n  },\n  "type": "panel"\n}\n```\n',
+    '```adf:panel\n{\n  "attrs": {\n    "panelType": "extra info"\n  }\n}\n```\n',
   )
-  assert.equal(carried({ attrs: { state: 2 }, type: 'taskItem' }), '```carry\n{\n  "attrs": {\n    "state": 2\n  },\n  "type": "taskItem"\n}\n```\n')
+  assert.equal(carried({ attrs: { state: 2 }, type: 'taskItem' }), '```adf:taskItem\n{\n  "attrs": {\n    "state": 2\n  }\n}\n```\n')
 })
 
 test('carries a block node mark in the reserved attribute', () => {
   const section = (...marks: AdfMark[]): AdfDocument => document({ marks, type: 'layoutSection' })
   assert.equal(markdown(adfToMarkdown(section({ type: 'breakout' }))), '!adf:layoutSection {marks="[{\\"type\\":\\"breakout\\"}]"}\n!adf:/layoutSection\n')
-  assert.equal(markdown(adfToMarkdown(section({ attrs: {}, type: 'breakout' }))), '!adf:layoutSection {marks="[{\\"type\\":\\"breakout\\"}]"}\n!adf:/layoutSection\n')
+  assert.equal(markdown(adfToMarkdown(section({ attrs: {}, type: 'breakout' }))), '!adf:layoutSection {marks="[{\\"attrs\\":{},\\"type\\":\\"breakout\\"}]"}\n!adf:/layoutSection\n')
+  assert.equal(markdown(adfToMarkdown(section())), '!adf:layoutSection {marks=empty}\n!adf:/layoutSection\n')
 })
 
 test('refuses the content a directive body has no room for', () => {
@@ -604,7 +600,7 @@ test('separates blocks in a container body by a blank line only where a directiv
 test('spells the image form for exactly the centered external media shape', () => {
   const url = 'https://example.com/moon.png'
   const single = (attrs: AdfAttributes, ...content: AdfNode[]): AdfDocument =>
-    document({ attrs: { layout: 'center' }, content: [{ attrs, content, type: 'media' }], type: 'mediaSingle' })
+    document({ attrs: { layout: 'center' }, content: [content.length === 0 ? { attrs, type: 'media' } : { attrs, content, type: 'media' }], type: 'mediaSingle' })
   assert.equal(markdown(adfToMarkdown(single({ alt: 'The moon', type: 'external', url }))), `![The moon](${url})\n`)
   assert.equal(markdown(adfToMarkdown(single({ type: 'external', url }))), `![](${url})\n`)
   assert.equal(markdown(adfToMarkdown(single({ alt: 'a [b] c', type: 'external', url }))), `![a \\[b\\] c](${url})\n`)
@@ -701,7 +697,8 @@ test('spells the directive marks around the longest run they cover', () => {
   const emitted = (...content: AdfNode[]): string => markdown(adfToMarkdown(document(paragraph(...content))))
   const underline: AdfMark = { type: 'underline' }
   assert.equal(emitted(marked('x', underline)), '!adf:underline[x]\n')
-  assert.equal(emitted(marked('a', underline), marked('b', underline)), '!adf:underline[ab]\n')
+  assert.equal(emitted(marked('a', underline), marked('b', underline)), '!adf:underline[a!adf:textBreak{}b]\n')
+  assert.equal(emitted(marked('a', { attrs: {}, type: 'underline' }), marked('b', underline)), '!adf:underline[a]{attrs=empty}!adf:underline[b]\n')
   assert.equal(emitted(marked('x', { attrs: { type: 'sub' }, type: 'subsup' })), '!adf:subsup[x]{type=sub}\n')
   assert.equal(emitted(marked('x', { attrs: { color: '#ae2e24' }, type: 'textColor' })), '!adf:textColor[x]{color="#ae2e24"}\n')
   assert.equal(emitted(marked('x', { attrs: { color: '#091e42', size: 2 }, type: 'border' })), '!adf:border[x]{color="#091e42" size=2}\n')
@@ -746,5 +743,5 @@ test('carries whitespace CommonMark strips in the reserved text directive', () =
 
 test("joins a mark run's segments as a walk rather than as one call's arguments", () => {
   const run = Array.from({ length: 200000 }, (): AdfNode => ({ marks: [{ type: 'strong' }], text: 'a', type: 'text' }))
-  assert.equal(markdown(adfToMarkdown(document({ content: run, type: 'paragraph' }))), `**${'a'.repeat(200000)}**\n`)
+  assert.equal(markdown(adfToMarkdown(document({ content: run, type: 'paragraph' }))), `**${Array.from({ length: 200000 }, () => 'a').join('!adf:textBreak{}')}**\n`)
 })

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

@@ -1,16 +1,16 @@
 import type { AdfDocument, AdfNode } from '../../adf/document.ts'
 import type { BlockNodeModel } from '../../adf/block-nodes.ts'
-import type { Flavour } from '../plain-conventions.ts'
+import type { Flavour } from '../plain/conventions.ts'
-import { adfDocumentFault, carriesOnly, nodeAttrs, nodeContent, nodeMarks } from '../../adf/document.ts'
+import { adfDocumentFault, holdsOnlyAttributes, isUnmarkedBareText, nodeAttrs, nodeContent } from '../../adf/document.ts'
-import { alertMarker, foldedAlertMarker, leadingMarker, readAlertMarker, readTaskMarker, taskMarker } from '../plain-conventions.ts'
+import { alertMarker, foldedAlertMarker, leadingMarker, readAlertMarker, readTaskMarker, taskMarker } from '../plain/conventions.ts'
-import { blockDirectiveForm, listBreakSpelling } from '../block-directive.ts'
+import { blockDirectiveForm, documentSpelling, listBreakSpelling } from '../block-directive.ts'
 import { blockNodeModel, blockNodes } from '../../adf/block-nodes.ts'
 import { carriedBlock } from '../opaque-carry.ts'
 import { emitInlineLine } from './inline-line.ts'
 import { failure, faulted, success, type ConvertErrorPath, type Result } from '../../result.ts'
 import { fencedCodeBlock } from '../commonmark/backtick-runs.ts'
 import { holdsNullCharacter, isBlankLine, isThematicBreak, markerInterruptsParagraph } from '../commonmark/grammar.ts'
-import { languageSlot } from '../code-language.ts'
+import { languageSlot, type LanguageSlot } from '../code-language.ts'
 import { largestNesting } from '../../nesting.ts'
 import { spellBlockDirectiveOpener } from './block-directive-spelling.ts'
 import { spellDirectiveCloser, spellDirectiveOpener } from '../directive-syntax.ts'
@@ -22,10 +22,10 @@ type BlockSpelling = 'commonmark' | 'directive' | 'list'
 type EmittedBlock = { headroom: number; spelling: BlockSpelling; text: string }
 type KeptSpelling = { block: EmittedBlock | undefined; depth: number }
 type PlacedBlock = Omit<EmittedBlock, 'headroom'> & { node: AdfNode }
+type PlacedBlocks = { blocks: readonly PlacedBlock[]; headroom: number }
 // Keyed by reference: only a caller building one object per position (the parse, the plain reduction) passes one; a consumer's document may share a node.
 export type SpellingMemo = Map<AdfNode, KeptSpelling>
-type Walk = { blocks: readonly PlacedBlock[]; headroom: number }
+type WalkedItem = { node: AdfNode; walk: PlacedBlocks }
-type WalkedItem = { node: AdfNode; walk: Walk }
 export type Writing = { flavour: Flavour; memo: SpellingMemo | undefined }
 
 export const largestListMarker = 999999999
@@ -40,14 +40,15 @@ export function writeMarkdown(document: AdfDocument, flavour: Flavour): Result<s
   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 ${document.version}`, [])
-  const walk = walkBlocks(nodeContent(document), [], 0, { flavour, memo: undefined })
+  if (document.content === undefined) return success(`${documentSpelling}\n`)
+  const walk = walkBlocks(document.content, [], 0, { flavour, memo: undefined })
   if (!walk.ok) return walk
   const text = joinBlocks(walk.value.blocks, 'document')
   return success(text === '' ? '' : `${text}\n`)
 }
 
 // headroom: the least slack any depth guard below the walk has.
-function walkBlocks(nodes: readonly AdfNode[], path: ConvertErrorPath, depth: number, writing: Writing): Result<Walk> {
+function walkBlocks(nodes: readonly AdfNode[], path: ConvertErrorPath, depth: number, writing: Writing): Result<PlacedBlocks> {
   let headroom = largestNesting - depth
   if (headroom < 0) return tooDeep(path)
   const blocks: PlacedBlock[] = []
@@ -75,15 +76,15 @@ function joinBlocks(blocks: readonly PlacedBlock[], container: BlockContainer):
 }
 
 function separationBetween(previous: PlacedBlock, next: PlacedBlock, container: BlockContainer): string {
-  const plainPair = previous.spelling !== 'directive' && next.spelling !== 'directive'
+  const bothCommonMark = previous.spelling !== 'directive' && next.spelling !== 'directive'
-  if (plainPair && next.spelling === 'list') {
+  if (bothCommonMark && next.spelling === 'list') {
     if (previous.spelling === 'list' && previous.node.type === next.node.type) {
       const gap = container === 'directive' ? '\n' : '\n\n'
       return `${gap}${listBreakSpelling}${gap}`
     }
     if (container === 'list-item') return interruptsParagraph(next.node) ? '\n' : '\n\n'
   }
-  return container === 'directive' && !plainPair ? '\n' : '\n\n'
+  return container === 'directive' && !bothCommonMark ? '\n' : '\n\n'
 }
 
 function interruptsParagraph(node: AdfNode): boolean {
@@ -180,13 +181,13 @@ function tryTaskList(node: AdfNode, path: ConvertErrorPath, depth: number, writi
   return lines.includes(undefined) ? failure('unsupported-node-shape', 'a task holds blocks no list item spells', path) : success({ headroom, spelling: 'list', text: lines.join('\n') })
 }
 
-function placedBlock(node: AdfNode, path: ConvertErrorPath, depth: number, writing: Writing): Result<Walk> {
+function placedBlock(node: AdfNode, path: ConvertErrorPath, depth: number, writing: Writing): Result<PlacedBlocks> {
   const block = emitBlock(node, path, depth, writing)
   return block.ok ? success({ blocks: [{ ...block.value, node }], headroom: block.value.headroom }) : block
 }
 
 // The marker leads the first paragraph, or stands as one where the blocks open with another.
-function taskBlocks(task: AdfNode, path: ConvertErrorPath, depth: number, writing: Writing): Result<Walk> {
+function taskBlocks(task: AdfNode, path: ConvertErrorPath, depth: number, writing: Writing): Result<PlacedBlocks> {
   const marker = taskMarker(nodeAttrs(task)['state'])
   const markerBlock: PlacedBlock = { node: { type: 'paragraph' }, spelling: 'commonmark', text: marker }
   if (task.type === 'taskItem') {
@@ -219,7 +220,7 @@ function directivePair(node: AdfNode, opener: string, body: string, headroom: nu
   return { headroom, spelling: 'directive', text: `${opener}\n${body === '' ? '' : `${body}\n`}${spellDirectiveCloser(node.type)}` }
 }
 
-function emitDirectiveBlock(node: AdfNode, model: BlockNodeModel, path: ConvertErrorPath, depth: number, walkBody: () => Result<Walk>): Result<EmittedBlock> {
+function emitDirectiveBlock(node: AdfNode, model: BlockNodeModel, path: ConvertErrorPath, depth: number, walkBody: () => Result<PlacedBlocks>): Result<EmittedBlock> {
   if (node.text !== undefined) return failure('unsupported-node-shape', `a ${node.type} carries no text: this one holds text`, path)
   if (blockDirectiveForm(node.type) === 'leaf' && nodeContent(node).length > 0) return failure('unsupported-node-shape', `a ${node.type} holds no content: this one holds some`, path)
   if (model.contentModel === 'code') return emitCodeDirective(node, model, path, depth)
@@ -229,7 +230,7 @@ function emitDirectiveBlock(node: AdfNode, model: BlockNodeModel, path: ConvertE
   return emitDirectiveBody(node, model, opener.value, path, walkBody)
 }
 
-function emitDirectiveBody(node: AdfNode, model: BlockNodeModel, opener: string, path: ConvertErrorPath, walkBody: () => Result<Walk>): Result<EmittedBlock> {
+function emitDirectiveBody(node: AdfNode, model: BlockNodeModel, opener: string, path: ConvertErrorPath, walkBody: () => Result<PlacedBlocks>): Result<EmittedBlock> {
   if (blockDirectiveForm(node.type) === 'leaf') return success({ headroom: Number.POSITIVE_INFINITY, spelling: 'directive', text: opener })
   if (model.contentModel === 'inline') {
     const line = emitInlineLine(nodeContent(node), 'paragraph', path, 'lossless')
@@ -242,7 +243,7 @@ function emitDirectiveBody(node: AdfNode, model: BlockNodeModel, opener: string,
 }
 
 function tryBlockquote(node: AdfNode, path: ConvertErrorPath, depth: number, writing: Writing): Result<EmittedBlock> | undefined {
-  if (!carriesOnly(node, [])) return undefined
+  if (!holdsOnlyAttributes(node, [])) return undefined
   const inner = walkBlocks(nodeContent(node), path, depth + 1, writing)
   if (!inner.ok) return inner
   const text = joinBlocks(inner.value.blocks, 'document')
@@ -251,47 +252,46 @@ function tryBlockquote(node: AdfNode, path: ConvertErrorPath, depth: number, wri
 }
 
 function tryCodeBlock(node: AdfNode, path: ConvertErrorPath): Result<EmittedBlock> | undefined {
-  if (!carriesOnly(node, ['language'])) return undefined
+  if (!holdsOnlyAttributes(node, ['language'])) return undefined
   const slot = languageSlot(nodeAttrs(node)['language'])
   if (slot.kind === 'attribute') return undefined
-  const text = codeBlockText(node, path)
+  const texts = fencedTexts(node, path)
-  if (!text.ok) return text
+  if (!texts.ok) return texts
-  return success(commonMarkText(fencedCodeBlock(slot.kind === 'fence' ? slot.info : '', text.value)))
+  const [only, ...others] = texts.value ?? []
+  if (only === undefined || others.length > 0) return undefined
+  return success(commonMarkText(fencedCodeBlock(slot.kind === 'fence' ? slot.info : '', only)))
 }
 
+// spec/flavour.md, The CommonMark blocks: one fence per text node, the language on each; with no fence to carry it, the attribute does.
 function emitCodeDirective(node: AdfNode, model: BlockNodeModel, path: ConvertErrorPath, depth: number): Result<EmittedBlock> {
-  const slot = languageSlot(nodeAttrs(node)['language'])
+  const texts = fencedTexts(node, path)
+  if (!texts.ok) return texts
+  if (texts.value === undefined) return commonMarkLine(carriedBlock(node, path, depth))
+  const slot: LanguageSlot = texts.value.length === 0 ? { kind: 'attribute' } : languageSlot(nodeAttrs(node)['language'])
   const opener = spellBlockDirectiveOpener(node, model, path, slot.kind === 'attribute' ? [] : ['language'])
   if (opener === undefined) return commonMarkLine(carriedBlock(node, path, depth))
   if (!opener.ok) return opener
-  const text = codeBlockText(node, path)
+  const info = slot.kind === 'fence' ? slot.info : ''
-  if (!text.ok) return text
+  return success(directivePair(node, opener.value, texts.value.map((text) => fencedCodeBlock(info, text)).join('\n')))
-  return success(directivePair(node, opener.value, fencedCodeBlock(slot.kind === 'fence' ? slot.info : '', text.value)))
 }
 
-function codeBlockText(node: AdfNode, path: ConvertErrorPath): Result<string> {
+// The text each fence holds, or `undefined` where a child is no plain text node, which the carry holds instead.
-  let text = ''
+function fencedTexts(node: AdfNode, path: ConvertErrorPath): Result<string[] | undefined> {
-  for (const [index, child] of nodeContent(node).entries()) {
+  if (node.content === undefined) return success([''])
+  if (node.content.some((child) => !isUnmarkedBareText(child))) return success(undefined)
+  const texts: string[] = []
+  for (const [index, child] of node.content.entries()) {
     const childPath = [...path, 'content', index]
-    if (
+    if (typeof child.text !== 'string' || child.text === '') return failure('unsupported-node-shape', 'a text node holds text: this one has none', childPath)
-      child.type !== 'text' ||
-      typeof child.text !== 'string' ||
-      child.text === '' ||
-      nodeContent(child).length > 0 ||
-      nodeMarks(child).length > 0 ||
-      Object.keys(nodeAttrs(child)).length > 0
-    ) {
-      return failure('unsupported-node-shape', `a codeBlock holds plain text nodes only: this ${child.type} node is not one`, childPath)
-    }
     if (/\r/.test(child.text)) return failure('unspellable-character', 'a codeBlock holds no carriage return CommonMark keeps: this text holds one', childPath)
     if (holdsNullCharacter(child.text)) return failure('unspellable-character', 'a codeBlock holds a null character CommonMark replaces', childPath)
-    text += child.text
+    texts.push(child.text)
   }
-  return success(text)
+  return success(texts)
 }
 
 function tryHeading(node: AdfNode, path: ConvertErrorPath, flavour: Flavour): Result<EmittedBlock> | undefined {
-  if (!carriesOnly(node, ['level'])) return undefined
+  if (!holdsOnlyAttributes(node, ['level'])) return undefined
   const level = nodeAttrs(node)['level']
   if (typeof level !== 'number' || !Number.isInteger(level) || level < 1 || level > 6) return undefined
   const hashes = '#'.repeat(level)
@@ -304,11 +304,11 @@ function tryHeading(node: AdfNode, path: ConvertErrorPath, flavour: Flavour): Re
 
 function tryList(node: AdfNode, path: ConvertErrorPath, depth: number, writing: Writing): Result<EmittedBlock> | undefined {
   const ordered = node.type === 'orderedList'
-  if (!carriesOnly(node, ordered ? ['order'] : [])) return undefined
+  if (!holdsOnlyAttributes(node, ordered ? ['order'] : [])) return undefined
   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
+  if (items.some((item) => item.type !== 'listItem' || !holdsOnlyAttributes(item, []))) return undefined
   const walked: WalkedItem[] = []
   let headroom = Number.POSITIVE_INFINITY
   for (const [offset, item] of items.entries()) {
@@ -340,7 +340,7 @@ function directiveItems(items: readonly WalkedItem[]): PlacedBlock[] {
 function listStart(node: AdfNode, items: number): number | undefined {
   if (node.type !== 'orderedList') return 0
   const start = nodeAttrs(node)['order']
-  if (typeof start !== 'number' || !Number.isInteger(start) || start < 0 || start > largestListMarker) return undefined
+  if (typeof start !== 'number' || !Number.isInteger(start) || start < 0 || Object.is(start, -0) || start > largestListMarker) return undefined
   return start + items - 1 > largestListMarker ? undefined : start
 }
 
@@ -356,13 +356,13 @@ function tryListItemLines(inner: string, marker: string): string | undefined {
 
 function tryParagraph(node: AdfNode, path: ConvertErrorPath, flavour: Flavour): Result<EmittedBlock> | undefined {
   const content = nodeContent(node)
-  if (content.length === 0 || !carriesOnly(node, [])) return undefined
+  if (content.length === 0 || !holdsOnlyAttributes(node, [])) return undefined
   const line = emitInlineLine(content, 'paragraph', path, flavour)
   if (!line.ok) return line
   return success(commonMarkText(line.value))
 }
 
 function tryRule(node: AdfNode): string | undefined {
-  if (!carriesOnly(node, []) || nodeContent(node).length > 0) return undefined
+  if (!holdsOnlyAttributes(node, []) || nodeContent(node).length > 0) return undefined
   return '---'
 }

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

@@ -5,6 +5,7 @@ import { blockArgument, markValues, marksAttribute } from '../block-directive.ts
 import { failure, success, type ConvertErrorPath, type Result } from '../../result.ts'
 import { isBareToken, spellAttributes, spellDirectiveOpener, spellJsonAttribute, spellVocabulary } from '../directive-syntax.ts'
 import { overNested } from '../../json-value.ts'
+import { spellEmptyKeys } from '../empty-keys.ts'
 import { vocabularyPairs } from '../../adf/attribute-vocabulary.ts'
 
 export function spellBlockDirectiveOpener(node: AdfNode, model: BlockNodeModel, path: ConvertErrorPath, spelledByBody: readonly string[] = []): Result<string> | undefined {
@@ -14,7 +15,7 @@ export function spellBlockDirectiveOpener(node: AdfNode, model: BlockNodeModel,
   const spelled = argumentAttribute === undefined ? spelledByBody : [argumentAttribute, ...spelledByBody]
   const pairs = vocabularyPairs(nodeAttrs(node), model.attributes, spelled)
   if (pairs === undefined) return undefined
-  const spelledPairs = spellVocabulary(pairs)
+  const spelledPairs = [...spellVocabulary(pairs), ...spellEmptyKeys(node)]
   const marks = nodeMarks(node)
   if (marks.length > 0) {
     const values = markValues(marks)

src/markdown/emit/image.ts

@@ -1,6 +1,6 @@
 import type { AdfNode } from '../../adf/document.ts'
 import type { ConvertErrorPath } from '../../result.ts'
-import { carriesOnly, nodeAttrs, nodeContent } from '../../adf/document.ts'
+import { holdsOnlyAttributes, nodeAttrs, nodeContent } from '../../adf/document.ts'
 import { serializeCanonicalJson } from '../../canonical-json.ts'
 import { tryImageLine } from './inline-line.ts'
 
@@ -16,8 +16,8 @@ export function tryImage(node: AdfNode, path: ConvertErrorPath): string | undefi
 function imageShape(node: AdfNode): { alt: string | undefined; url: string } | undefined {
   const content = nodeContent(node)
   const media = content[0]
-  if (!carriesOnly(node, ['layout']) || serializeCanonicalJson(nodeAttrs(node), 'compact') !== centeredMediaSingle) return undefined
+  if (!holdsOnlyAttributes(node, ['layout']) || serializeCanonicalJson(nodeAttrs(node), 'compact') !== centeredMediaSingle) return undefined
-  if (media === undefined || content.length !== 1 || media.type !== 'media' || !carriesOnly(media, imageAttributes) || nodeContent(media).length > 0) return undefined
+  if (media === undefined || content.length !== 1 || media.type !== 'media' || !holdsOnlyAttributes(media, imageAttributes) || nodeContent(media).length > 0) return undefined
   const attrs = nodeAttrs(media)
   const alt = attrs['alt']
   const url = attrs['url']

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

@@ -2,9 +2,10 @@ import type { AdfNode } from '../../adf/document.ts'
 import type { InlineNodeModel } from '../../adf/inline-nodes.ts'
 import { nodeAttrs } from '../../adf/document.ts'
 import { spellAttributes, spellVocabulary } from '../directive-syntax.ts'
+import { spellEmptyKeys } from '../empty-keys.ts'
 import { vocabularyPairs } from '../../adf/attribute-vocabulary.ts'
 
 export function spellInlineNodeAttributes(node: AdfNode, model: InlineNodeModel): string | undefined {
   const pairs = vocabularyPairs(nodeAttrs(node), model.attributes, model.textAttribute === undefined ? [] : [model.textAttribute])
-  return pairs === undefined ? undefined : spellAttributes(spellVocabulary(pairs))
+  return pairs === undefined ? undefined : spellAttributes([...spellVocabulary(pairs), ...spellEmptyKeys(node)])
 }

src/markdown/emit/inline-line.ts

@@ -1,19 +1,19 @@
 import type { AdfMark, AdfNode } from '../../adf/document.ts'
-import type { Flavour } from '../plain-conventions.ts'
+import type { Flavour } from '../plain/conventions.ts'
 import type { InlineNodeModel } from '../../adf/inline-nodes.ts'
 import type { LineContainer } from '../line-container.ts'
 import { assembleInlineLine, isSyntax, type InlineEscaping, type InlineSegment, type MarkRun, type NodeRange } from './line-escaping.ts'
 import { carriedInline } from '../opaque-carry.ts'
 import { claimsLine, holdsNullCharacter, trimTrailingSpace } from '../commonmark/grammar.ts'
 import { commonMarkLink, linkHref, markSpelling, spellMarkAttributes } from '../mark-spellings.ts'
+import { identicalMark, isBareText, nodeAttrs, nodeContent, nodeMarks } from '../../adf/document.ts'
 import { escapeUnbalanced, spellDestination } from '../commonmark/link-syntax.ts'
 import { failure, faulted, success, type ConvertErrorPath, type Result } from '../../result.ts'
-import { highlightDelimiter } from '../plain-conventions.ts'
+import { highlightDelimiter } from '../plain/conventions.ts'
 import { inlineNodeModel } from '../../adf/inline-nodes.ts'
+import { joinsWhenRead, textBreakSpelling } from '../adjacent-text.ts'
 import { largestNesting } from '../../nesting.ts'
 import { longestBacktickRun } from '../commonmark/backtick-runs.ts'
-import { nodeAttrs, nodeContent, nodeMarks } from '../../adf/document.ts'
-import { sameMark } from '../../adf/editor-normal.ts'
 import { slotLineEndingFault, spellInlineDirectiveOpener, spellInlineLeafDirective } from '../directive-syntax.ts'
 import { spellInlineNodeAttributes } from './inline-directive-spelling.ts'
 import { spellTextDirective } from '../text-directive.ts'
@@ -114,7 +114,7 @@ function lineSegments(nodes: readonly AdfNode[], container: LineContainer, path:
   const emission = emitRun(nodes, 0, 0, context)
   if (!emission.ok) return emission
   if (emission.value.carry !== undefined) return emission
-  return success({ segments: carryStrippedWhitespace(emission.value.segments) })
+  return success({ segments: spellEdgeWhitespace(emission.value.segments) })
 }
 
 function attemptLine(segments: readonly InlineSegment[], container: LineContainer, path: ConvertErrorPath, flavour: Flavour): Result<LineAttempt> {
@@ -137,32 +137,32 @@ function lineVerdict(segments: readonly InlineSegment[], container: LineContaine
 }
 
 // spec/flavour.md, Inline nodes.
-function carryStrippedWhitespace(segments: readonly InlineSegment[]): InlineSegment[] {
+function spellEdgeWhitespace(segments: readonly InlineSegment[]): InlineSegment[] {
-  const carried: InlineSegment[] = []
+  const spelled: InlineSegment[] = []
   for (const [index, segment] of segments.entries()) {
     const previous = segments[index - 1]
     const next = segments[index + 1]
     const leading = previous === undefined || previous.text.includes('\n')
     const trailing = next === undefined || next.text.includes('\n')
-    carried.push(...carryEdges(segment, leading, trailing))
+    spelled.push(...edgeWhitespaceSegments(segment, leading, trailing))
   }
-  return carried
+  return spelled
 }
 
-function carryEdges(segment: InlineSegment, leading: boolean, trailing: boolean): InlineSegment[] {
+function edgeWhitespaceSegments(segment: InlineSegment, leading: boolean, trailing: boolean): InlineSegment[] {
   if (segment.escaping !== 'backslash' && segment.escaping !== 'bracketed') return [segment]
   const head = leading ? (/^[ \t]+/.exec(segment.text)?.[0] ?? '') : ''
   const body = segment.text.slice(head.length)
   const middle = trailing ? trimTrailingSpace(body) : body
   const tail = body.slice(middle.length)
   const edges: InlineSegment[] = []
-  if (head !== '') edges.push(carriedText(head))
+  if (head !== '') edges.push(textDirectiveSegment(head))
   if (middle !== '') edges.push({ escaping: segment.escaping, text: middle })
-  if (tail !== '') edges.push(carriedText(tail))
+  if (tail !== '') edges.push(textDirectiveSegment(tail))
   return edges
 }
 
-function carriedText(text: string): InlineSegment {
+function textDirectiveSegment(text: string): InlineSegment {
   return syntax(spellTextDirective(text))
 }
 
@@ -186,6 +186,7 @@ function emitRun(nodes: readonly AdfNode[], depth: number, firstIndex: number, c
   const runs = inlineRuns(nodes, depth, firstIndex, context.carried)
   const segments: InlineSegment[] = []
   for (const [offset, run] of runs.entries()) {
+    if (takesTextBreak(runs[offset - 1], run, context.carried)) segments.push(syntax(textBreakSpelling))
     const runContext = { ...context, atBlockEnd: context.atBlockEnd && offset === runs.length - 1 }
     const emitted = run.kind === 'plain' ? emitLeaf(run.node, runContext, run.index) : emitMarkedRun(run.nodes, run.mark, depth, run.index, runContext)
     if (!emitted.ok) return emitted
@@ -206,12 +207,18 @@ function inlineRuns(nodes: readonly AdfNode[], depth: number, firstIndex: number
       continue
     }
     const previous = runs[runs.length - 1]
-    if (previous?.kind === 'marked' && sameMark(previous.mark, mark)) previous.nodes.push(node)
+    if (previous?.kind === 'marked' && identicalMark(previous.mark, mark)) previous.nodes.push(node)
     else runs.push({ index, kind: 'marked', mark, nodes: [node] })
   }
   return runs
 }
 
+function takesTextBreak(previous: InlineRun | undefined, run: InlineRun, carried: ReadonlySet<number>): boolean {
+  if (previous?.kind !== 'plain' || run.kind !== 'plain') return false
+  if (carries(previous.node, carried, previous.index) || carries(run.node, carried, run.index)) return false
+  return joinsWhenRead(previous.node, run.node)
+}
+
 function nodePath(context: InlineContext, index: number): ConvertErrorPath {
   return [...context.path, 'content', index]
 }
@@ -260,15 +267,20 @@ function emitInlineDirective(node: AdfNode, model: InlineNodeModel, index: numbe
   return success({ segments: [syntax(spellInlineDirectiveOpener(node.type)), ...content, syntax(`]${attributes}`)] })
 }
 
+function textHoldingContent(node: AdfNode, path: ConvertErrorPath): Result<never> | undefined {
+  return node.type === 'text' && nodeContent(node).length > 0 ? failure('unsupported-node-shape', 'a text node holds no content: this one holds some', path) : undefined
+}
+
 function emitText(node: AdfNode, context: InlineContext, index: number, path: ConvertErrorPath): Result<Emission> {
-  if (Object.keys(nodeAttrs(node)).length > 0) return success({ carry: { first: index, last: index } })
+  const holding = textHoldingContent(node, path)
+  if (holding !== undefined) return holding
+  if (!isBareText(node)) 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 (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'
   const parts = node.text.split(/(\n+)/).filter((part) => part !== '')
-  return success({ segments: parts.map((part) => (part.startsWith('\n') ? carriedText(part) : { escaping, text: part })) })
+  return success({ segments: parts.map((part) => (part.startsWith('\n') ? textDirectiveSegment(part) : { escaping, text: part })) })
 }
 
 function emitMarkedRun(nodes: readonly AdfNode[], mark: AdfMark, depth: number, index: number, context: InlineContext): Result<Emission> {
@@ -277,7 +289,7 @@ function emitMarkedRun(nodes: readonly AdfNode[], mark: AdfMark, depth: number,
   if (mark.type === 'backgroundColor' && context.flavour === 'plain') return emitHighlight(nodes, depth, range, context)
   const spelling = markSpelling(mark.type)
   if (spelling === undefined) return success({ carry: range })
-  const attributes = spellMarkAttributes(mark, spelling.attributes)
+  const attributes = spellMarkAttributes(mark, spelling)
   if (attributes === undefined) return success({ carry: range })
   if (spelling.kind === 'code') return emitCodeSpan(nodes, depth, range, path)
   if (spelling.kind === 'emphasis') return emitEmphasis(nodes, spelling.spelling, depth, range, context)
@@ -293,11 +305,11 @@ function emitEmphasis(nodes: readonly AdfNode[], spelling: string, depth: number
   const inner = emitRun(nodes, depth + 1, range.first, context)
   if (!inner.ok) return inner
   if (inner.value.carry !== undefined) return inner
-  const carried = carryStrippedWhitespace(inner.value.segments)
+  const spelled = spellEdgeWhitespace(inner.value.segments)
   return success({
     segments: [
       { emphasis: 'open', escaping: 'none', nodes: { ...range, depth }, text: spelling },
-      ...carried,
+      ...spelled,
       { emphasis: 'close', escaping: 'none', nodes: { ...range, depth }, text: spelling },
     ],
   })
@@ -312,19 +324,21 @@ function emitHighlight(nodes: readonly AdfNode[], depth: number, range: NodeRang
   })
 }
 
+// Each node its own span: CommonMark reads two adjacent text nodes in one span back as one.
 function emitCodeSpan(nodes: readonly AdfNode[], depth: number, range: NodeRange, path: ConvertErrorPath): Result<Emission> {
-  let text = ''
+  const spans: string[] = []
   for (const node of nodes) {
-    if (node.type !== 'text' || nodeMarks(node).length !== depth + 1) return success({ carry: range })
+    const holding = textHoldingContent(node, path)
-    if (typeof node.text !== 'string' || node.text === '') return failure('unsupported-node-shape', 'a text node holds text: this one has none', path)
+    if (holding !== undefined) return holding
-    if (nodeContent(node).length > 0) return failure('unsupported-node-shape', 'a text node holds no content: this one holds some', path)
+    if (!isBareText(node) || nodeMarks(node).length !== depth + 1) return success({ carry: range })
-    text += node.text
+    const { text } = node
+    if (typeof text !== 'string' || text === '') return failure('unsupported-node-shape', 'a text node holds text: this one has none', path)
+    if (/[\n\r]/.test(text)) return success({ carry: range })
+    if (holdsNullCharacter(text)) return failure('unspellable-character', 'a code span holds a null character CommonMark replaces', path)
+    const fence = '`'.repeat(longestBacktickRun(text) + 1)
+    spans.push(`${fence}${needsPadding(text) ? ` ${text} ` : text}${fence}`)
   }
-  if (/[\n\r]/.test(text)) return success({ carry: range })
+  return success({ segments: [syntax(spans.join(textBreakSpelling))] })
-  if (holdsNullCharacter(text)) return failure('unspellable-character', 'a code span holds a null character CommonMark replaces', path)
-  const fence = '`'.repeat(longestBacktickRun(text) + 1)
-  const padded = needsPadding(text) ? ` ${text} ` : text
-  return success({ segments: [syntax(`${fence}${padded}${fence}`)] })
 }
 
 function needsPadding(text: string): boolean {

src/markdown/emit/line-escaping.ts

@@ -1,10 +1,10 @@
-import type { Flavour } from '../plain-conventions.ts'
+import type { Flavour } from '../plain/conventions.ts'
 import type { LineContainer } from '../line-container.ts'
 import { backslashEscape, escapesLineClaim, inlineHtmlConstruct, opensBracketedAutolink, opensEmailAutolink, type LinePosition } from '../commonmark/grammar.ts'
 import { backtickRun, closingBacktickRun } from '../commonmark/backtick-runs.ts'
 import { claimsDirectivePrefix } from '../directive-syntax.ts'
 import { delimiterFlags, isWordCharacter, matchEmphasis, runLength } from '../commonmark/emphasis-matching.ts'
-import { highlightDelimiter, highlightFlanking } from '../plain-conventions.ts'
+import { highlightDelimiter, highlightFlanking } from '../plain/conventions.ts'
 import { isBareDelimiterRow } from '../pipe-table-syntax.ts'
 import { opensLinkDefinition } from '../commonmark/link-reference-definitions.ts'
 import { readEntityReference } from '../commonmark/entity-references.ts'

src/markdown/emit/pipe-table.ts

@@ -1,7 +1,7 @@
 import type { AdfNode } from '../../adf/document.ts'
 import type { ConvertErrorPath } from '../../result.ts'
-import type { Flavour } from '../plain-conventions.ts'
+import type { Flavour } from '../plain/conventions.ts'
-import { carriesOnly, nodeContent } from '../../adf/document.ts'
+import { holdsOnlyAttributes, nodeContent } from '../../adf/document.ts'
 import { spellPipeDelimiter, spellPipeRow } from '../pipe-table-syntax.ts'
 import { tryPipeCell } from './inline-line.ts'
 
@@ -26,16 +26,16 @@ export function tryPipeTable(node: AdfNode, path: ConvertErrorPath, flavour: Fla
 function pipeRows(node: AdfNode): AdfNode[][] | undefined {
   const rows = nodeContent(node)
   const columns = rows[0] === undefined ? 0 : nodeContent(rows[0]).length
-  if (!carriesOnly(node, []) || columns === 0) return undefined
+  if (!holdsOnlyAttributes(node, []) || columns === 0) return undefined
   const grid: AdfNode[][] = []
   for (const [index, row] of rows.entries()) {
     const cells = nodeContent(row)
-    if (row.type !== 'tableRow' || !carriesOnly(row, []) || cells.length !== columns) return undefined
+    if (row.type !== 'tableRow' || !holdsOnlyAttributes(row, []) || cells.length !== columns) return undefined
     const wanted = index === 0 ? 'tableHeader' : 'tableCell'
     const paragraphs: AdfNode[] = []
     for (const cell of cells) {
       const paragraph = plainParagraph(cell)
-      if (paragraph === undefined || cell.type !== wanted || !carriesOnly(cell, [])) return undefined
+      if (paragraph === undefined || cell.type !== wanted || !holdsOnlyAttributes(cell, [])) return undefined
       paragraphs.push(paragraph)
     }
     grid.push(paragraphs)
@@ -46,6 +46,6 @@ function pipeRows(node: AdfNode): AdfNode[][] | undefined {
 function plainParagraph(cell: AdfNode): AdfNode | undefined {
   const content = nodeContent(cell)
   const paragraph = content[0]
-  if (paragraph === undefined || content.length !== 1 || paragraph.type !== 'paragraph' || !carriesOnly(paragraph, [])) return undefined
+  if (paragraph === undefined || content.length !== 1 || paragraph.type !== 'paragraph' || !holdsOnlyAttributes(paragraph, [])) return undefined
   return paragraph
 }

src/markdown/empty-keys.ts

@@ -0,0 +1,32 @@
+import type { DirectiveAttributes, DirectiveValue, Read } from './directive-syntax.ts'
+import type { EmptyKey } from '../adf/document.ts'
+import { emptyKeys } from '../adf/document.ts'
+import { unsupportedNodeShape } from './directive-syntax.ts'
+
+type EmptyKeysRead = { empty: ReadonlySet<EmptyKey>; rest: Map<string, DirectiveValue> }
+
+const emptyValue = 'empty'
+
+// spec/flavour.md, Attributes: no attribute value spells an empty object or array.
+export function spellEmptyKeys(held: Parameters<typeof emptyKeys>[0]): [string, string][] {
+  return emptyKeys(held).map((key) => [key, emptyValue])
+}
+
+export function spellsEmpty(value: DirectiveValue | undefined): boolean {
+  return value?.spelling === emptyValue
+}
+
+// `held` is whether the directive spells an attribute outside {attrs}: an argument or a content slot.
+export function readEmptyKeys(type: string, attributes: DirectiveAttributes, keys: readonly EmptyKey[], held: boolean): Read<EmptyKeysRead> {
+  const rest = new Map(attributes)
+  const empty = new Set<EmptyKey>()
+  for (const key of keys) {
+    const spelled = rest.get(key)
+    if (spelled === undefined) continue
+    if (!spellsEmpty(spelled)) return { fault: unsupportedNodeShape(`the reserved key ${key} takes only the value ${emptyValue}: this one spells ${key}=${spelled.spelling}`) }
+    empty.add(key)
+    rest.delete(key)
+  }
+  if (empty.has('attrs') && (held || [...rest.keys()].some((key) => key !== 'marks'))) return { fault: unsupportedNodeShape(`${type} spells attrs=empty beside another attribute, an argument or a [content] slot: drop attrs=empty, or the rest`) }
+  return { value: { empty, rest } }
+}

src/markdown/mark-spellings.ts

@@ -7,6 +7,7 @@ import { holdsEntityReference } from './commonmark/entity-references.ts'
 import { isAutolink } from './commonmark/grammar.ts'
 import { isMarkType, markAttributes } from '../adf/mark-attributes.ts'
 import { nodeAttrs, nodeMarks } from '../adf/document.ts'
+import { spellEmptyKeys } from './empty-keys.ts'
 import { vocabularyPairs } from '../adf/attribute-vocabulary.ts'
 
 type Spelling = { kind: 'code' | 'directive' | 'link'; spelling?: undefined } | { kind: 'emphasis'; spelling: string }
@@ -55,7 +56,10 @@ function isBareLink(nodes: readonly AdfNode[], href: string, marksInside: number
   return nodes.length === 1 && node !== undefined && node.type === 'text' && node.text === href && nodeMarks(node).length === marksInside
 }
 
-export function spellMarkAttributes(mark: AdfMark, vocabulary: AttributeVocabulary): string | undefined {
+// `undefined` where the spelling holds no such attrs: only a directive spells attrs=empty.
-  const pairs = vocabularyPairs(nodeAttrs(mark), vocabulary, [])
+export function spellMarkAttributes(mark: AdfMark, spelling: MarkSpelling): string | undefined {
-  return pairs === undefined ? undefined : spellAttributes(spellVocabulary(pairs))
+  const pairs = vocabularyPairs(nodeAttrs(mark), spelling.attributes, [])
+  const empty = spellEmptyKeys(mark)
+  if (pairs === undefined || (empty.length > 0 && spelling.kind !== 'directive')) return undefined
+  return spellAttributes([...spellVocabulary(pairs), ...empty])
 }

src/markdown/opaque-carry.ts

@@ -1,32 +1,49 @@
 import type { AdfNode } from '../adf/document.ts'
 import type { DirectiveSpan, Read } from './directive-syntax.ts'
 import type { JsonSpelling } from '../canonical-json.ts'
+import type { JsonValue } from '../json-value.ts'
 import { failure, success, type ConvertErrorPath, type Result } from '../result.ts'
 import { fencedCodeBlock } from './commonmark/backtick-runs.ts'
+import { infoStringCarries } from './commonmark/grammar.ts'
 import { isAdfNode } from '../adf/document.ts'
 import { isJsonValue, nestingDepth, overNested } from '../json-value.ts'
 import { largestNesting } from '../nesting.ts'
-import { malformedDirective, readSoleStringAttribute, spellAttributes, spellInlineLeafDirective, spellStringAttribute, unsupportedNodeShape } from './directive-syntax.ts'
+import { directiveEscape, malformedDirective, readSoleStringAttribute, spellAttributes, spellDirectiveOpener, spellInlineLeafDirective, spellStringAttribute, unsupportedNodeShape } from './directive-syntax.ts'
 import { serializeCanonicalJson } from '../canonical-json.ts'
 
+export const carryFencePrefix = 'adf:'
+
 export const carryName = 'carry'
 
 const jsonAttribute = 'json'
 
+// spec/flavour.md, The opaque carry: the info string names the type wherever it carries the type back.
 export function carriedBlock(node: AdfNode, path: ConvertErrorPath, depth: number): Result<{ headroom: number; text: string }> {
-  const json = carriedJson(node, 'two-space', path, largestNesting - depth)
+  const { type, ...untyped } = node
+  const named = infoStringCarries(type)
+  const json = carriedJson(node, named ? untyped : node, 'two-space', path, largestNesting - depth)
   if (!json.ok) return json
-  return success({ headroom: json.value.headroom, text: fencedCodeBlock(carryName, json.value.json) })
+  return success({ headroom: json.value.headroom, text: fencedCodeBlock(`${carryFencePrefix}${named ? type : ''}`, json.value.json) })
 }
 
 export function carriedInline(node: AdfNode, path: ConvertErrorPath): Result<string> {
-  const json = carriedJson(node, 'compact', path, largestNesting)
+  const json = carriedJson(node, node, 'compact', path, largestNesting)
   if (!json.ok) return json
   return success(spellInlineLeafDirective(carryName, spellAttributes([[jsonAttribute, spellStringAttribute(json.value.json)]])))
 }
 
-export function readCarriedBlock(body: string, depth: number): Read<AdfNode> {
+// The type a fence's info string names, `undefined` where the info string opens no carry.
-  return readCarriedJson(body, 'two-space', largestNesting - depth)
+export function carryFenceType(info: string): string | undefined {
+  return info.startsWith(carryFencePrefix) ? info.slice(carryFencePrefix.length) : undefined
+}
+
+export function readCarriedBlock(type: string, body: string, depth: number): Read<AdfNode> {
+  if (type !== '' && !infoStringCarries(type)) {
+    return { fault: unsupportedNodeShape(`the carry fence names a type no info string carries back: spell it ${carryFencePrefix} with the type in the JSON; ${fenceEscape(type)}`) }
+  }
+  const read = readCarriedJson(body, 'two-space', largestNesting - depth, type)
+  if (read.fault !== undefined || type !== '' || !infoStringCarries(read.value.type)) return read
+  return { fault: unsupportedNodeShape(`the ${carryFencePrefix} fence holds a type its info string can carry: spell the fence ${carryFencePrefix}${read.value.type} and drop type from the JSON`) }
 }
 
 export function readCarriedInline(span: DirectiveSpan): Read<AdfNode> | undefined {
@@ -36,28 +53,44 @@ export function readCarriedInline(span: DirectiveSpan): Read<AdfNode> | undefine
   return readCarriedJson(spelled.value, 'compact', largestNesting)
 }
 
-function carriedJson(node: AdfNode, spelling: JsonSpelling, path: ConvertErrorPath, levels: number): Result<{ headroom: number; json: string }> {
+function carriedJson(node: AdfNode, spelled: object, spelling: JsonSpelling, path: ConvertErrorPath, levels: number): Result<{ headroom: number; json: string }> {
   const headroom = levels - nestingDepth(node)
-  if (!isJsonValue(node) || headroom < 0) {
+  if (!isJsonValue(spelled) || headroom < 0) {
     return failure('unsupported-nesting-depth', `a carried node's JSON nests deeper than the ${levels} levels its position leaves`, path)
   }
-  return success({ headroom, json: serializeCanonicalJson(node, spelling) })
+  return success({ headroom, json: serializeCanonicalJson(spelled, spelling) })
 }
 
-function readCarriedJson(raw: string, spelling: JsonSpelling, levels: number): Read<AdfNode> {
+// `type` is the one the fence's info string names, `undefined` for the inline carry.
+function readCarriedJson(raw: string, spelling: JsonSpelling, levels: number, type?: string): Read<AdfNode> {
+  const wayOut = type === undefined ? directiveEscape : fenceEscape(type)
   const parsed = parseJsonText(raw)
-  if (parsed === undefined) return { fault: malformedDirective('the opaque carry holds invalid JSON') }
+  if (parsed === undefined) return { fault: malformedDirective(`the opaque carry holds invalid JSON; ${wayOut}`) }
   const { value } = parsed
   if (!isJsonValue(value)) return { fault: unsupportedNodeShape('the opaque carry holds a number JSON cannot spell') }
-  if (overNested(value, levels)) {
+  const typed = type === undefined || type === '' ? { value } : typedValue(value, type)
+  if (typed.fault !== undefined) return typed
+  const held = typed.value
+  if (overNested(held, levels)) {
     return { fault: { code: 'unsupported-nesting-depth', message: `a carried node's JSON nests deeper than the ${levels} levels its position leaves` } }
   }
   if (serializeCanonicalJson(value, spelling) !== raw) {
     const shape = spelling === 'compact' ? 'compact, keys sorted' : 'two-space indent, keys sorted'
-    return { fault: unsupportedNodeShape(`the opaque carry spells its node's JSON canonically: ${shape}`) }
+    return { fault: unsupportedNodeShape(`the opaque carry spells its node's JSON canonically: ${shape}; ${wayOut}`) }
   }
-  if (!isAdfNode(value)) return { fault: unsupportedNodeShape("the opaque carry holds one ADF node's JSON: this JSON is no ADF node") }
+  if (!isAdfNode(held)) return { fault: unsupportedNodeShape(`the opaque carry holds one ADF node's JSON: this JSON is no ADF node; ${wayOut}`) }
-  return { value }
+  return { value: held }
+}
+
+// A code fence the carry claims stays code under the directive, whose language rides the attribute.
+function fenceEscape(type: string): string {
+  return `${spellDirectiveOpener('codeBlock', undefined, spellAttributes([['language', spellStringAttribute(`${carryFencePrefix}${type}`)]]))} around a bare fence keeps it a code block`
+}
+
+function typedValue(value: JsonValue, type: string): Read<JsonValue> {
+  if (value === null || typeof value !== 'object' || Array.isArray(value)) return { value }
+  if ('type' in value) return { fault: unsupportedNodeShape(`the ${carryFencePrefix}${type} fence names its node's type: this JSON holds a type as well; ${fenceEscape(type)}`) }
+  return { value: { ...value, type } }
 }
 
 function parseJsonText(raw: string): { value: unknown } | undefined {

src/markdown/parse/directive-marks.ts

@@ -3,8 +3,9 @@ import type { ConvertFault } from '../../result.ts'
 import type { DirectiveAttributes } from '../directive-syntax.ts'
 import type { MarkSpelling } from '../mark-spellings.ts'
 import { directivePrefix } from '../directive-syntax.ts'
-import { failure, success, type ConvertErrorPath, type Result } from '../../result.ts'
+import { failure, faulted, success, type ConvertErrorPath, type Result } from '../../result.ts'
 import { markSpelling } from '../mark-spellings.ts'
+import { readEmptyKeys } from '../empty-keys.ts'
 import { readVocabulary } from './directive-attributes.ts'
 
 export function readDirectiveMark(name: string, attributes: DirectiveAttributes, path: ConvertErrorPath): Result<AdfMark> | undefined {
@@ -12,8 +13,11 @@ export function readDirectiveMark(name: string, attributes: DirectiveAttributes,
   if (spelling === undefined) return undefined
   const markdown = markdownForm(spelling)
   if (markdown !== undefined) return failure('unsupported-node-shape', `${name} is spelled ${markdown}, never as a directive`, path)
-  const attrs = readVocabulary(name, attributes, spelling.attributes, undefined, path)
+  const empty = readEmptyKeys(name, attributes, ['attrs'], false)
+  if (empty.fault !== undefined) return faulted(empty.fault, path)
+  const attrs = readVocabulary(name, empty.value.rest, spelling.attributes, undefined, path)
   if (!attrs.ok) return attrs
+  if (empty.value.empty.has('attrs')) return success({ attrs: {}, type: name })
   return success(Object.keys(attrs.value).length === 0 ? { type: name } : { attrs: attrs.value, type: name })
 }
 

src/markdown/parse/directive-nodes.ts

@@ -1,18 +1,20 @@
-import type { AdfAttributes, AdfMark, AdfNode } from '../../adf/document.ts'
+import type { AdfAttributes, AdfMark, AdfNode, EmptyKey } from '../../adf/document.ts'
 import type { BlockNodeModel } from '../../adf/block-nodes.ts'
 import type { ConvertFault } from '../../result.ts'
 import type { DirectiveAttributes, DirectiveValue } from '../directive-syntax.ts'
 import type { Elsewhere } from './directive-attributes.ts'
-import { attributeNestingMessage, nodeAttrs, nodeContent, nodeMarks } from '../../adf/document.ts'
+import { attributeNestingMessage, isUnmarkedBareText } from '../../adf/document.ts'
 import { attributeValue, directivePrefix, spellAttributeValue, unknownDirectiveFault } from '../directive-syntax.ts'
 import { blockArgument, blockDirectiveForm, marksAttribute, readMarkValues } from '../block-directive.ts'
 import { blockNodeModel } from '../../adf/block-nodes.ts'
-import { carryName } from '../opaque-carry.ts'
+import { carryFencePrefix, carryName } from '../opaque-carry.ts'
 import { failure, faulted, success, type ConvertErrorPath, type Result } from '../../result.ts'
 import { inlineMarkSpellingFault } from './directive-marks.ts'
 import { inlineNodeModel } from '../../adf/inline-nodes.ts'
+import { readEmptyKeys, spellsEmpty } from '../empty-keys.ts'
 import { readVocabulary } from './directive-attributes.ts'
 import { slotLineEndingFault } from '../directive-syntax.ts'
+import { textBreakName } from '../adjacent-text.ts'
 import { textDirectiveName } from '../text-directive.ts'
 
 export type BlockDirectiveNode = { contentModel: BlockNodeModel['contentModel']; node: AdfNode }
@@ -24,12 +26,15 @@ export function readBlockDirectiveNode(
   path: ConvertErrorPath,
 ): Result<BlockDirectiveNode> {
   if (name === carryName) {
-    return failure('malformed-directive', `the name ${carryName} is reserved for the opaque carry, whose block form is the ${carryName} fence`, path)
+    return failure('malformed-directive', `the name ${carryName} is reserved for the opaque carry, whose block form is the ${carryFencePrefix} fence`, path)
   }
   const model = blockNodeModel(name)
   if (model === undefined) return faulted(inlineSpellingFault(name) ?? unknownDirectiveFault(name), path)
   const argumentKey = blockArgument(name)
-  const rest = new Map(attributes)
+  const spelled = attributes.get(marksAttribute)
+  const empty = readEmptyKeys(name, attributes, spellsEmpty(spelled) ? ['attrs', 'content', 'marks'] : ['attrs', 'content'], argument !== undefined)
+  if (empty.fault !== undefined) return faulted(empty.fault, path)
+  const { rest } = empty.value
   rest.delete(marksAttribute)
   const elsewhere: Elsewhere | undefined = argumentKey === undefined ? undefined : { key: argumentKey, slot: 'argument' }
   const attrs = readVocabulary(name, rest, model.attributes, elsewhere, path)
@@ -38,10 +43,9 @@ export function readBlockDirectiveNode(
     if (argumentKey === undefined) return failure('unsupported-node-shape', `${name} takes no argument: this one spells one`, path)
     attrs.value[argumentKey] = argument
   }
-  const spelled = attributes.get(marksAttribute)
+  const marks: Result<AdfMark[] | undefined> = spelled === undefined || spellsEmpty(spelled) ? success(undefined) : readMarks(name, spelled, path)
-  const marks: Result<AdfMark[] | undefined> = spelled === undefined ? success(undefined) : readMarks(name, spelled, path)
   if (!marks.ok) return marks
-  return success({ contentModel: model.contentModel, node: namedNode(name, attrs.value, marks.value) })
+  return success({ contentModel: model.contentModel, node: namedNode(name, attrs.value, marks.value, empty.value.empty) })
 }
 
 export function readInlineDirectiveNode(
@@ -55,7 +59,9 @@ export function readInlineDirectiveNode(
   const slot = model.textAttribute
   if (slot === undefined && content !== undefined) return failure('unsupported-node-shape', `${name} takes no content: this one holds some`, path)
   const elsewhere: Elsewhere | undefined = slot === undefined ? undefined : { key: slot, slot: 'content' }
-  const attrs = readVocabulary(name, attributes, model.attributes, elsewhere, path)
+  const empty = readEmptyKeys(name, attributes, ['attrs', 'content', 'marks'], slot !== undefined && content !== undefined)
+  if (empty.fault !== undefined) return faulted(empty.fault, path)
+  const attrs = readVocabulary(name, empty.value.rest, model.attributes, elsewhere, path)
   if (!attrs.ok) return attrs
   if (slot !== undefined && content !== undefined) {
     const text = slotText(content)
@@ -66,14 +72,14 @@ export function readInlineDirectiveNode(
     if (spans !== undefined) return faulted(spans, path)
     attrs.value[slot] = text
   }
-  return success(namedNode(name, attrs.value, undefined))
+  return success(namedNode(name, attrs.value, undefined, empty.value.empty))
 }
 
 // A name the other position spells names that spelling, never the code a later MINOR may fill (docs/decisions.md §Which code a cause takes).
 function inlineSpellingFault(name: string): ConvertFault | undefined {
   const mark = inlineMarkSpellingFault(name)
   if (mark !== undefined) return mark
-  if (inlineNodeModel(name) === undefined && name !== textDirectiveName) return undefined
+  if (inlineNodeModel(name) === undefined && name !== textDirectiveName && name !== textBreakName) return undefined
   return { code: 'unsupported-node-shape', message: `${name} takes the inline form, ${directivePrefix}${name}{…}, never the block form` }
 }
 
@@ -86,7 +92,7 @@ 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' || nodeMarks(only).length > 0 || Object.keys(nodeAttrs(only)).length > 0 || nodeContent(only).length > 0 || typeof only.text !== 'string') return undefined
+  if (only === undefined || !isUnmarkedBareText(only) || typeof only.text !== 'string') return undefined
   return only.text
 }
 
@@ -100,7 +106,9 @@ function readMarks(type: string, spelled: DirectiveValue, path: ConvertErrorPath
   return success(marks)
 }
 
-function namedNode(type: string, attrs: AdfAttributes, marks: readonly AdfMark[] | undefined): AdfNode {
+function namedNode(type: string, attrs: AdfAttributes, marks: readonly AdfMark[] | undefined, empty: ReadonlySet<EmptyKey>): AdfNode {
-  const named = Object.keys(attrs).length === 0 ? { type } : { attrs, type }
+  const node: AdfNode = Object.keys(attrs).length > 0 || empty.has('attrs') ? { attrs, type } : { type }
-  return marks === undefined ? named : { ...named, marks: [...marks] }
+  if (empty.has('content')) node.content = []
+  if (marks !== undefined || empty.has('marks')) node.marks = [...(marks ?? [])]
+  return node
 }

src/markdown/parse/inline-content.ts

@@ -1,7 +1,7 @@
 import type { AdfMark, AdfNode } from '../../adf/document.ts'
 import type { DirectiveSpan, NestedSpans } from '../directive-syntax.ts'
 import type { EmphasisPairing } from '../commonmark/emphasis-matching.ts'
-import type { Flavour } from '../plain-conventions.ts'
+import type { Flavour } from '../plain/conventions.ts'
 import type { LineContainer } from '../line-container.ts'
 import type { LinkDefinition } from '../commonmark/link-syntax.ts'
 import { backslashEscape, decodeTextEscapes, inlineHtmlConstruct, readBracketedAutolink, readEmailAutolink, trimTrailingSpace } from '../commonmark/grammar.ts'
@@ -9,11 +9,11 @@ import { backtickRun, closingBacktickRun } from '../commonmark/backtick-runs.ts'
 import { commonMarkLink, linkHref } from '../mark-spellings.ts'
 import { delimiterFlags, matchEmphasis, runLength } from '../commonmark/emphasis-matching.ts'
 import { failure, faulted, success, type ConvertErrorPath, type Result } from '../../result.ts'
-import { highlightDelimiter, highlightFlanking } from '../plain-conventions.ts'
+import { highlightDelimiter, highlightFlanking } from '../plain/conventions.ts'
+import { identicalMarks, mergeAdjacentText, nodeAttrs, nodeMarks } from '../../adf/document.ts'
 import { inlineNodeModel } from '../../adf/inline-nodes.ts'
-import { mergeAdjacentText, sameMarks } from '../../adf/editor-normal.ts'
+import { joinsWhenRead, textBreakName, textBreakSpelling } from '../adjacent-text.ts'
 import { noSpans, readInlineDirective } from '../directive-syntax.ts'
-import { nodeAttrs, nodeMarks } from '../../adf/document.ts'
 import { normalizeLabel, readInlineTarget, readLabel } from '../commonmark/link-syntax.ts'
 import { openingLinkTakesDirective } from '../emit/inline-line.ts'
 import { readCarriedInline } from '../opaque-carry.ts'
@@ -21,7 +21,17 @@ import { readDirectiveMark } from './directive-marks.ts'
 import { readInlineDirectiveNode } from './directive-nodes.ts'
 import { readTextDirective } from '../text-directive.ts'
 
-export type InlineContent = { carry?: undefined; image: AdfNode; nodes?: undefined } | { carry: boolean; image?: undefined; nodes: AdfNode[] }
+export type InlineContent = { image: AdfNode; nodes?: undefined } | { image?: undefined; nodes: AdfNode[] }
+
+// The text break leaf: it holds no marks, and stands between the nodes it parts until the outermost content checks and drops it.
+type TextBreak = { kind: 'textBreak' }
+
+// A node whose marks are its own — an opaque carry, or an inline node spelling marks=empty: no mark spelling wraps it, and it joins no neighbour.
+type OwnMarks = { kind: 'ownMarks'; node: AdfNode }
+
+type Inline = AdfNode | OwnMarks | TextBreak
+
+type Scanned = { image: AdfNode; nodes?: undefined } | { image?: undefined; nodes: Inline[] }
 
 export type LinkDefinitions = ReadonlyMap<string, LinkDefinition>
 
@@ -33,9 +43,10 @@ type Pairing = EmphasisPairing<Run>
 
 type Piece =
   | Bracket
-  | { kind: 'carry'; node: AdfNode }
+  | OwnMarks
   | { alt: string; kind: 'image'; node: AdfNode }
-  | { kind: 'nodes'; nodes: AdfNode[] }
+  | { kind: 'nodes'; nodes: Inline[] }
+  | TextBreak
   | { canClose: boolean; canOpen: boolean; character: string; kind: 'run'; length: number }
   | { closes: boolean; kind: 'highlight'; opens: boolean }
 
@@ -56,21 +67,41 @@ type Scan = {
   spans: NestedSpans
 }
 
-type SlotContent = { carry: boolean; nodes: AdfNode[] }
+// What a directive's content slot inherits from the content holding it.
+type SharedScan = Pick<Scan, 'definitions' | 'path'>
 
-const carriedInMark = 'no mark spelling wraps an opaque carry: the carried node restores exactly, marks included'
+type SlotContent = { nodes: Inline[] }
+
+const ownMarksInMark = 'move the opaque carry, or the node spelling marks=empty, out of the mark spelling: it holds its own marks'
 const editorHighlight: AdfMark = { attrs: { color: '#f8e6a0' }, type: 'backgroundColor' }
 const hreflessLink = 'the link mark spells its href: this one spells none'
 const imageAlone = 'an image fits only as a paragraph of its own: this one sits inside other content'
 const linkInLink = 'no link wraps a link: the [content] this one marks already holds one'
 const spellableLink = 'link takes the directive form only where CommonMark cannot spell it: this one it can, as [text](url "title") or <url>'
+const textBreak: TextBreak = { kind: 'textBreak' }
 
+// The outermost content: only here does a text break see both its neighbours.
 export function parseInlineContent(source: string, definitions: LinkDefinitions, path: ConvertErrorPath, container: LineContainer, flavour: Flavour): Result<InlineContent> {
-  return parseInline(source, definitions, path, container, noSpans, flavour === 'plain')
+  const scan = freshScan(source, { definitions, path }, { container, highlights: flavour === 'plain', spans: noSpans })
+  const scanned = scanInline(scan)
+  if (!scanned.ok) return scanned
+  if (scanned.value.image !== undefined) return success({ image: scanned.value.image })
+  const nodes = partText(scanned.value.nodes, scan)
+  if (!nodes.ok) return nodes
+  if (scan.openingSpellableLink) {
+    const takesDirective = openingLinkTakesDirective(nodes.value, path)
+    if (!takesDirective.ok) return takesDirective
+    if (!takesDirective.value) return failure('unsupported-node-shape', spellableLink, path)
+  }
+  return success({ nodes: nodes.value })
 }
 
-function parseInline(source: string, definitions: LinkDefinitions, path: ConvertErrorPath, container: LineContainer | undefined, spans: NestedSpans, highlights: boolean): Result<InlineContent> {
+function freshScan(source: string, shared: SharedScan, own: Pick<Scan, 'container' | 'highlights' | 'spans'>): Scan {
-  const scan: Scan = { container, deactivatedBefore: 0, definitions, highlights, openingSpellableLink: false, path, pending: '', pieces: [], source, spans }
+  return { ...shared, ...own, deactivatedBefore: 0, openingSpellableLink: false, pending: '', pieces: [], source }
+}
+
+function scanInline(scan: Scan): Result<Scanned> {
+  const { source } = scan
   let index = 0
   while (index < source.length) {
     switch (source.charAt(index)) {
@@ -103,7 +134,7 @@ function parseInline(source: string, definitions: LinkDefinitions, path: Convert
         index = readCharacter(scan, index)
     }
   }
-  flush(scan, container !== undefined)
+  flush(scan, scan.container !== undefined)
   return assemble(scan)
 }
 
@@ -205,8 +236,9 @@ function directivePiece(scan: Scan, span: DirectiveSpan, index: number): Result<
   const carried = readCarriedInline(span)
   if (carried !== undefined) {
     if (carried.fault !== undefined) return faulted(carried.fault, scan.path)
-    return success({ kind: 'carry', node: carried.value })
+    return success({ kind: 'ownMarks', node: carried.value })
   }
+  if (span.name === textBreakName) return span.content === undefined && span.attributes.size === 0 ? success(textBreak) : failure('unsupported-node-shape', `${textBreakName} spells the bare leaf form, ${textBreakSpelling}: this one spells more`, scan.path)
   const text = readTextDirective(span)
   if (text?.fault !== undefined) return faulted(text.fault, scan.path)
   if (text !== undefined) return success({ kind: 'nodes', nodes: [{ text: text.value, type: 'text' }] })
@@ -214,27 +246,29 @@ function directivePiece(scan: Scan, span: DirectiveSpan, index: number): Result<
   if (!slot.ok) return slot
   const mark = readDirectiveMark(span.name, span.attributes, scan.path)
   if (mark !== undefined) return mark.ok ? directiveMarkPiece(scan, span.name, mark.value, slot.value, index) : mark
-  const node = readInlineDirectiveNode(span.name, span.attributes, slot.value?.nodes, scan.path)
+  const content = slot.value?.nodes
+  if (content?.some(isTextBreak) === true) return failure('unsupported-node-shape', `delete ${textBreakSpelling} from this content slot: a slot holds one text node`, scan.path)
+  const node = readInlineDirectiveNode(span.name, span.attributes, content === undefined ? undefined : adfNodes(content), scan.path)
   if (!node.ok) return node
-  return success({ kind: 'nodes', nodes: [node.value] })
+  return success(node.value.marks === undefined ? { kind: 'nodes', nodes: [node.value] } : { kind: 'ownMarks', node: node.value })
 }
 
 function directiveMarkPiece(scan: Scan, name: string, mark: AdfMark, slot: SlotContent | undefined, index: number): Result<Piece> {
   if (slot === undefined || slot.nodes.length === 0) {
     return failure('unsupported-node-shape', `the ${name} mark wraps the [content] it marks: this one wraps none`, scan.path)
   }
-  if (slot.carry) return failure('unsupported-node-shape', carriedInMark, scan.path)
+  if (slot.nodes.some(holdsOwnMarks)) return failure('unsupported-node-shape', ownMarksInMark, scan.path)
   const refused = mark.type === 'link' ? refuseLinkDirective(scan, mark, slot.nodes, index) : undefined
   if (refused !== undefined) return refused
   return success({ kind: 'nodes', nodes: applyMark(slot.nodes, mark) })
 }
 
 // spec/flavour.md, Marks. A link opening a paragraph may still need the directive form for the line it opens, which `assemble` asks the emitter.
-function refuseLinkDirective(scan: Scan, mark: AdfMark, nodes: readonly AdfNode[], index: number): Result<Piece> | undefined {
+function refuseLinkDirective(scan: Scan, mark: AdfMark, nodes: readonly Inline[], index: number): Result<Piece> | undefined {
   const href = linkHref(nodeAttrs(mark))
   if (href === undefined) return failure('unsupported-node-shape', hreflessLink, scan.path)
   if (marksLink(nodes)) return failure('unsupported-node-shape', linkInLink, scan.path)
-  if (commonMarkLink(nodeAttrs(mark), href, nodes, 0, scan.container === undefined) === undefined) return undefined
+  if (commonMarkLink(nodeAttrs(mark), href, adfNodes(nodes), 0, scan.container === undefined) === undefined) return undefined
   if (index !== 0 || scan.container !== 'paragraph') return failure('unsupported-node-shape', spellableLink, scan.path)
   scan.openingSpellableLink = true
   return undefined
@@ -242,7 +276,8 @@ function refuseLinkDirective(scan: Scan, mark: AdfMark, nodes: readonly AdfNode[
 
 function slotContent(scan: Scan, span: DirectiveSpan): Result<SlotContent | undefined> {
   if (span.content === undefined) return success(undefined)
-  const parsed = parseInline(span.content, scan.definitions, scan.path, undefined, span.spans, false)
+  const { definitions, path } = scan
+  const parsed = scanInline(freshScan(span.content, { definitions, path }, { container: undefined, highlights: false, spans: span.spans }))
   if (!parsed.ok) return parsed
   if (parsed.value.image !== undefined) return failure('unmappable-image', imageAlone, scan.path)
   return success(parsed.value)
@@ -258,35 +293,65 @@ function pushNode(scan: Scan, node: AdfNode): void {
   scan.pieces.push({ kind: 'nodes', nodes: [node] })
 }
 
-function assemble(scan: Scan): Result<InlineContent> {
+function assemble(scan: Scan): Result<Scanned> {
   const only = scan.pieces[0]
   if (scan.pieces.length === 1 && only?.kind === 'image') return success({ image: only.node })
   if (holdsImage(scan.pieces)) return failure('unmappable-image', imageAlone, scan.path)
-  const nodes = resolveNodes(scan.pieces, scan.path, true)
+  const nodes = resolveNodes(scan.pieces, scan, true)
   if (!nodes.ok) return nodes
-  if (scan.openingSpellableLink) {
+  return success({ nodes: nodes.value })
-    const takesDirective = openingLinkTakesDirective(nodes.value, scan.path)
-    if (!takesDirective.ok) return takesDirective
-    if (!takesDirective.value) return failure('unsupported-node-shape', spellableLink, scan.path)
-  }
-  return success({ carry: holdsCarry(scan.pieces), nodes: nodes.value })
 }
 
-function holdsCarry(pieces: readonly Piece[]): boolean {
+// spec/flavour.md, Inline nodes: the leaf builds no node, so only the pair it parts spells it.
-  return pieces.some((piece) => piece.kind === 'carry')
+function partText(items: readonly Inline[], scan: Scan): Result<AdfNode[]> {
+  const parted: AdfNode[] = []
+  for (const [index, item] of items.entries()) {
+    if (!isTextBreak(item)) {
+      parted.push(isNode(item) ? item : item.node)
+      continue
+    }
+    const previous = items[index - 1]
+    const next = items[index + 1]
+    if (previous === undefined || next === undefined || !isNode(previous) || !isNode(next) || !joinsWhenRead(previous, next)) {
+      return failure('unsupported-node-shape', `delete ${textBreakSpelling} here: it stands only between two runs of text with the same formatting, which would otherwise read as one`, scan.path)
+    }
+  }
+  return success(parted)
+}
+
+function isNode(item: Inline): item is AdfNode {
+  return !('kind' in item)
+}
+
+function isTextBreak(item: Inline): item is TextBreak {
+  return 'kind' in item && item.kind === 'textBreak'
+}
+
+// The nodes the items hold, own-marks ones unwrapped and text breaks dropped.
+function adfNodes(items: readonly Inline[]): AdfNode[] {
+  const nodes: AdfNode[] = []
+  for (const item of items) {
+    if (isNode(item)) nodes.push(item)
+    else if (!isTextBreak(item)) nodes.push(item.node)
+  }
+  return nodes
+}
+
+function holdsOwnMarks(item: Inline | Piece): boolean {
+  return 'kind' in item && item.kind === 'ownMarks'
 }
 
 function holdsImage(pieces: readonly Piece[]): boolean {
   return pieces.some((piece) => piece.kind === 'image')
 }
 
-// A carry rides its own piece: the carried node's marks restore with it rather than riding a spelling, so the guard below answers for it.
+// A node whose marks are its own rides its own piece, its marks restoring with it rather than riding a spelling, so the guard below answers for it.
 function holdsLink(pieces: readonly Piece[]): boolean {
   return pieces.some((piece) => piece.kind === 'nodes' && marksLink(piece.nodes))
 }
 
-function marksLink(nodes: readonly AdfNode[]): boolean {
+function marksLink(nodes: readonly Inline[]): boolean {
-  return nodes.some((node) => nodeMarks(node).some((mark) => mark.type === 'link'))
+  return adfNodes(nodes).some((node) => nodeMarks(node).some((mark) => mark.type === 'link'))
 }
 
 function readDelimiterRun(scan: Scan, index: number): number {
@@ -382,8 +447,8 @@ function closeLink(scan: Scan, at: number, inner: readonly Piece[], definition:
     return success(false)
   }
   if (holdsImage(inner)) return failure('unmappable-image', imageAlone, scan.path)
-  if (holdsCarry(inner)) return failure('unsupported-node-shape', carriedInMark, scan.path)
+  if (inner.some(holdsOwnMarks)) return failure('unsupported-node-shape', ownMarksInMark, scan.path)
-  const resolved = resolveNodes(inner, scan.path, true)
+  const resolved = resolveNodes(inner, scan, true)
   if (!resolved.ok) return resolved
   const nodes = resolved.value
   // An empty link text gives the mark no node to ride, so the brackets stay text.
@@ -411,7 +476,7 @@ function truncatePieces(scan: Scan, to: number): void {
 
 function closeImage(scan: Scan, at: number, inner: readonly Piece[], definition: LinkDefinition): Result<null> {
   if (definition.title !== undefined) return failure('unmappable-image', 'no media node carries a link title', scan.path)
-  const resolved = imageAlt(inner, scan.path)
+  const resolved = imageAlt(inner, scan)
   if (!resolved.ok) return resolved
   const alt = resolved.value
   const attrs = alt === '' ? { type: 'external', url: definition.destination } : { alt, type: 'external', url: definition.destination }
@@ -420,10 +485,11 @@ function closeImage(scan: Scan, at: number, inner: readonly Piece[], definition:
   return success(null)
 }
 
-function imageAlt(inner: readonly Piece[], path: ConvertErrorPath): Result<string> {
+function imageAlt(inner: readonly Piece[], scan: Scan): Result<string> {
-  const nodes = resolveNodes(inner, path, false)
+  const nodes = resolveNodes(inner, scan, false)
   if (!nodes.ok) return nodes
-  return success(nodes.value.map(altText).join(''))
+  if (nodes.value.some(isTextBreak)) return failure('unsupported-node-shape', `delete ${textBreakSpelling} from this image description: the description reads as plain alt text`, scan.path)
+  return success(adfNodes(nodes.value).map(altText).join(''))
 }
 
 // spec/flavour.md, The CommonMark image: the description's plain text, the content slot included.
@@ -435,22 +501,39 @@ function altText(node: AdfNode): string {
 }
 
 // An image's alt text is plain, so `highlights` is off there and every `==` stays text.
-function resolveNodes(pieces: readonly Piece[], path: ConvertErrorPath, highlights: boolean): Result<AdfNode[]> {
+function resolveNodes(pieces: readonly Piece[], scan: Scan, highlights: boolean): Result<Inline[]> {
   const nodes = pieces.map(pieceNodes)
   const runs = delimiterRuns(pieces)
   const pairings = matchEmphasis(runs)
   writeUnpaired(nodes, runs, pairings)
-  if (!markPairings(pieces, nodes, pairings)) return failure('unsupported-node-shape', carriedInMark, path)
+  if (!markPairings(pieces, nodes, pairings)) return failure('unsupported-node-shape', ownMarksInMark, scan.path)
   markHighlights(pieces, nodes, highlights ? pairedHighlights(pieces, nodes) : [])
-  return success(mergeAdjacentText(nodes.flat()))
+  return success(mergeReadText(nodes.flat()))
+}
+
+// A text break and a node whose marks are its own are walls: the text on either side joins only its own side.
+function mergeReadText(items: readonly Inline[]): Inline[] {
+  const merged: Inline[] = []
+  let run: AdfNode[] = []
+  for (const item of items) {
+    if (isNode(item)) {
+      run.push(item)
+      continue
+    }
+    for (const node of mergeAdjacentText(run, joinsWhenRead)) merged.push(node)
+    merged.push(item)
+    run = []
+  }
+  for (const node of mergeAdjacentText(run, joinsWhenRead)) merged.push(node)
+  return merged
 }
 
 // Only `imageAlt` reaches the image arm: everywhere else an image amid other content is refused first.
 // A highlight delimiter holds an empty text node until it pairs, so the emphasis around it marks it.
-function pieceNodes(piece: Piece): AdfNode[] {
+function pieceNodes(piece: Piece): Inline[] {
   switch (piece.kind) {
-    case 'carry':
+    case 'ownMarks':
-      return [piece.node]
+      return [piece]
     case 'highlight':
       return [{ text: '', type: 'text' }]
     case 'image':
@@ -461,6 +544,8 @@ function pieceNodes(piece: Piece): AdfNode[] {
       return bracketNodes(piece)
     case 'run':
       return []
+    case 'textBreak':
+      return [piece]
   }
 }
 
@@ -473,7 +558,7 @@ function delimiterRuns(pieces: readonly Piece[]): Run[] {
 }
 
 // A run gives its delimiters up from the head closing and the tail opening; what is left between them is text.
-function writeUnpaired(nodes: AdfNode[][], runs: readonly Run[], pairings: readonly Pairing[]): void {
+function writeUnpaired(nodes: Inline[][], runs: readonly Run[], pairings: readonly Pairing[]): void {
   const heads = new Map<Run, number>()
   const tails = new Map<Run, number>()
   for (const pairing of pairings) {
@@ -488,23 +573,23 @@ function writeUnpaired(nodes: AdfNode[][], runs: readonly Run[], pairings: reado
 }
 
 // Innermost pairing first, so prepending leaves the marks array outermost first (spec/flavour.md, Marks).
-function markPairings(pieces: readonly Piece[], nodes: AdfNode[][], pairings: readonly Pairing[]): boolean {
+function markPairings(pieces: readonly Piece[], nodes: Inline[][], pairings: readonly Pairing[]): boolean {
   for (const pairing of pairings) {
     const mark: AdfMark = { type: markType(pairing.opener.character, pairing.used) }
     for (let index = pairing.opener.index + 1; index < pairing.closer.index; index += 1) {
-      if (pieces[index]?.kind === 'carry') return false
+      if (pieces[index]?.kind === 'ownMarks') return false
       nodes[index] = applyMark(nodes[index] ?? [], mark)
     }
   }
   return true
 }
 
-function highlightDelimiters(pieces: readonly Piece[], nodes: readonly AdfNode[][]): HighlightDelimiter[] {
+function highlightDelimiters(pieces: readonly Piece[], nodes: readonly Inline[][]): HighlightDelimiter[] {
   const found: HighlightDelimiter[] = []
   let line = 0
   let position = 0
   for (const [index, piece] of pieces.entries()) {
-    const held = nodes[index] ?? []
+    const held = adfNodes(nodes[index] ?? [])
     const [holder] = held
     if (piece.kind === 'highlight' && holder !== undefined) {
       found.push({ closes: piece.closes, holder, index, line, opens: piece.opens, position })
@@ -520,7 +605,7 @@ function highlightDelimiters(pieces: readonly Piece[], nodes: readonly AdfNode[]
 }
 
 // Each opener takes the next closer holding at least one character after it, both in one line and under the same marks.
-function pairedHighlights(pieces: readonly Piece[], nodes: readonly AdfNode[][]): { closer: number; opener: number }[] {
+function pairedHighlights(pieces: readonly Piece[], nodes: readonly Inline[][]): { closer: number; opener: number }[] {
   const found = highlightDelimiters(pieces, nodes)
   const paired: { closer: number; opener: number }[] = []
   let closer = 0
@@ -531,7 +616,7 @@ function pairedHighlights(pieces: readonly Piece[], nodes: readonly AdfNode[][])
     let candidate = found[closer]
     while (candidate !== undefined && (!candidate.closes || candidate.position < earliest)) candidate = found[(closer += 1)]
     if (candidate === undefined) break
-    if (candidate.line !== opener.line || !sameMarks(opener.holder, candidate.holder)) continue
+    if (candidate.line !== opener.line || !identicalMarks(nodeMarks(opener.holder), nodeMarks(candidate.holder))) continue
     paired.push({ closer: candidate.index, opener: opener.index })
     resume = candidate.position + highlightDelimiter.length
   }
@@ -539,9 +624,9 @@ function pairedHighlights(pieces: readonly Piece[], nodes: readonly AdfNode[][])
 }
 
 // Atlassian's schema refuses a highlight on code, a node holds one highlight, and a rebuilt node would lose its attributes.
-function markHighlights(pieces: readonly Piece[], nodes: AdfNode[][], paired: readonly { closer: number; opener: number }[]): void {
+function markHighlights(pieces: readonly Piece[], nodes: Inline[][], paired: readonly { closer: number; opener: number }[]): void {
   for (const [index, piece] of pieces.entries()) {
-    if (piece.kind === 'highlight') nodes[index] = (nodes[index] ?? []).map((holder) => ({ ...holder, text: highlightDelimiter }))
+    if (piece.kind === 'highlight') nodes[index] = adfNodes(nodes[index] ?? []).map((holder) => ({ ...holder, text: highlightDelimiter }))
   }
   for (const { closer, opener } of paired) {
     nodes[opener] = []
@@ -550,7 +635,8 @@ function markHighlights(pieces: readonly Piece[], nodes: AdfNode[][], paired: re
   }
 }
 
-function highlighted(node: AdfNode): AdfNode {
+function highlighted(node: Inline): Inline {
+  if (!isNode(node)) return node
   const marks = nodeMarks(node)
   if (node.type !== 'text' || Object.keys(nodeAttrs(node)).length > 0 || marks.some((mark) => mark.type === 'code' || mark.type === 'backgroundColor')) return node
   return { ...node, marks: [editorHighlight, ...marks] }
@@ -562,8 +648,9 @@ function markType(character: string, used: number): string {
 }
 
 // A node cannot carry one mark type twice (docs/decisions.md §No schema validation).
-function applyMark(nodes: readonly AdfNode[], mark: AdfMark): AdfNode[] {
+function applyMark(nodes: readonly Inline[], mark: AdfMark): Inline[] {
   return nodes.map((node) => {
+    if (!isNode(node)) return node
     const marks = nodeMarks(node)
     return marks.some((carried) => carried.type === mark.type) ? node : { ...node, marks: [mark, ...marks] }
   })

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

@@ -84,9 +84,24 @@ function table(...rows: AdfNode[]): AdfNode {
   return { content: rows, type: 'table' }
 }
 
-test('builds an empty document from input holding no block', () => {
+test('builds an empty document from input holding no block, and one holding no content key from the doc directive alone', () => {
-  assert.deepEqual(markdownToAdf(''), { ok: true, value: { type: 'doc', version: 1 } })
+  assert.deepEqual(markdownToAdf(''), { ok: true, value: { content: [], type: 'doc', version: 1 } })
-  assert.deepEqual(content(markdownToAdf('\n \n\t\n')), [])
+  assert.deepEqual(markdownToAdf('\n \n\t\n'), { ok: true, value: { content: [], type: 'doc', version: 1 } })
+  assert.deepEqual(markdownToAdf('!adf:doc {content=none}\n'), { ok: true, value: { type: 'doc', version: 1 } })
+  assert.deepEqual(markdownToAdf('\n!adf:doc {content=none}\n\n'), { ok: true, value: { type: 'doc', version: 1 } })
+  const form = 'unsupported-node-shape: doc spells the one form !adf:doc {content=none}: this one spells another'
+  assert.equal(content(markdownToAdf('!adf:doc\n')), form)
+  assert.equal(content(markdownToAdf('!adf:doc x {content=none}\n')), form)
+  assert.equal(
+    content(markdownToAdf('!adf:doc {content=empty}\n')),
+    'unsupported-node-shape: an empty document is empty markdown, and !adf:doc {content=none} spells a document holding no content key: this one spells content=empty',
+  )
+  assert.equal(content(markdownToAdf('!adf:doc {content="none"}\n')), form)
+  const alone = 'unsupported-node-shape: delete the !adf:doc {content=none} line to give the document content: it stands only as the whole document'
+  assert.equal(content(markdownToAdf('x\n\n!adf:doc {content=none}\n')), alone)
+  assert.equal(content(markdownToAdf('!adf:panel info\n!adf:doc {content=none}\n!adf:/panel\n')), alone)
+  assert.equal(content(markdownToAdf('!adf:doc\n!adf:/doc\n')), 'malformed-directive: doc takes no body, so no !adf:/doc closes it; \\!adf: keeps the prefix literal')
+  assert.equal(content(markdownToAdf('a !adf:doc{content=none}\n')), 'unsupported-node-shape: doc takes the block form, !adf:doc, never the inline form')
 })
 
 test('builds one paragraph from the lines a blank line does not part', () => {
@@ -151,9 +166,13 @@ test('reads the codeBlock directive body as the node content, the info string it
 
 test('names the slot a codeBlock spells its language outside of', () => {
   const slot = 'unsupported-node-shape: codeBlock spells its language in the fence info string, or in the attribute where no info string carries it back'
-  assert.equal(content(markdownToAdf('!adf:codeBlock {language=rust wrap=true}\n```\nx\n```\n!adf:/codeBlock\n')), slot)
+  assert.equal(content(markdownToAdf('!adf:codeBlock {language=rust wrap=true}\n```\nx\n```\n!adf:/codeBlock\n')), "unsupported-node-shape: move language=rust to the fences' info strings: they can spell this language")
+  assert.equal(
+    content(markdownToAdf('!adf:codeBlock {language="c sharp"}\n```\nx\n```\n```\ny\n```\n!adf:/codeBlock\n')),
+    "unsupported-node-shape: move language=\"c sharp\" to the fences' info strings: they can spell this language",
+  )
   assert.equal(content(markdownToAdf('!adf:codeBlock {language=rust}\n```sql\nx\n```\n!adf:/codeBlock\n')), slot)
-  assert.equal(content(markdownToAdf('!adf:codeBlock {wrap=true}\n```carry\nx\n```\n!adf:/codeBlock\n')), slot)
+  assert.equal(content(markdownToAdf('!adf:codeBlock {wrap=true}\n```adf:x\nx\n```\n!adf:/codeBlock\n')), slot)
   assert.equal(content(markdownToAdf('!adf:codeBlock {wrap=true}\n```a\\b\nx\n```\n!adf:/codeBlock\n')), slot)
 })
 
@@ -343,18 +362,28 @@ test('names the position a directive name the other one spells belongs to', () =
 })
 
 test('names the reserved carry name a block directive spells', () => {
-  const reserved = 'malformed-directive: the name carry is reserved for the opaque carry, whose block form is the carry fence'
+  const reserved = 'malformed-directive: the name carry is reserved for the opaque carry, whose block form is the adf: fence'
   assert.equal(content(markdownToAdf('!adf:carry\n')), reserved)
   assert.equal(content(markdownToAdf('!adf:carry\nx\n!adf:/carry\n')), reserved)
   assert.deepEqual(content(markdownToAdf('```adf\nx\n```\n')), [{ attrs: { language: 'adf' }, content: [text('x')], type: 'codeBlock' }])
+  assert.deepEqual(content(markdownToAdf('```carry\nx\n```\n')), [{ attrs: { language: 'carry' }, content: [text('x')], type: 'codeBlock' }])
 })
 
 const carried = '!adf:carry{json="{\\"type\\":\\"placeholder\\"}"}'
 
-test('reads the carry fence back to the node its JSON holds', () => {
+test('reads the carry fence back to the node its info string names and its JSON holds', () => {
-  assert.deepEqual(content(markdownToAdf('```carry\n{\n  "attrs": {\n    "url": "https://example.com/x"\n  },\n  "type": "blockCard"\n}\n```\n')), [
+  assert.deepEqual(content(markdownToAdf('```adf:blockCard\n{\n  "attrs": {\n    "url": "https://example.com/x"\n  }\n}\n```\n')), [
     { attrs: { url: 'https://example.com/x' }, type: 'blockCard' },
   ])
+  assert.deepEqual(content(markdownToAdf('```adf:\n{\n  "type": "a`b"\n}\n```\n')), [{ type: 'a`b' }])
+  assert.equal(
+    content(markdownToAdf('```adf:blockCard\n{\n  "type": "blockCard"\n}\n```\n')),
+    'unsupported-node-shape: the adf:blockCard fence names its node\'s type: this JSON holds a type as well; !adf:codeBlock {language="adf:blockCard"} around a bare fence keeps it a code block',
+  )
+  assert.equal(content(markdownToAdf('```adf:\n{\n  "type": "blockCard"\n}\n```\n')), 'unsupported-node-shape: the adf: fence holds a type its info string can carry: spell the fence adf:blockCard and drop type from the JSON')
+  assert.equal(content(markdownToAdf('```adf:\n{}\n```\n')), "unsupported-node-shape: the opaque carry holds one ADF node's JSON: this JSON is no ADF node; !adf:codeBlock {language=\"adf:\"} around a bare fence keeps it a code block")
+  const unnamed = 'unsupported-node-shape: the carry fence names a type no info string carries back: spell it adf: with the type in the JSON; !adf:codeBlock {language="adf:\\\\"} around a bare fence keeps it a code block'
+  assert.equal(content(markdownToAdf('```adf:\\\\\n{}\n```\n')), unnamed)
 })
 
 test('reads the inline carry back to the node its json attribute holds', () => {
@@ -363,26 +392,31 @@ test('reads the inline carry back to the node its json attribute holds', () => {
   ])
 })
 
-test('names the invalid JSON no opaque carry holds', () => {
+test('names the invalid JSON no opaque carry holds, and the spelling that keeps it literal', () => {
-  const invalid = 'malformed-directive: the opaque carry holds invalid JSON'
+  const invalid = 'malformed-directive: the opaque carry holds invalid JSON; '
-  assert.equal(content(markdownToAdf('```carry\n{"type":\n```\n')), invalid)
+  const fence = `${invalid}!adf:codeBlock {language="adf:x"} around a bare fence keeps it a code block`
-  assert.equal(content(markdownToAdf('```carry\n```\n')), invalid)
+  assert.equal(content(markdownToAdf('```adf:x\n{"attrs":\n```\n')), fence)
-  assert.equal(content(markdownToAdf('!adf:carry{json="{"}\n')), invalid)
+  assert.equal(content(markdownToAdf('```adf:x\n```\n')), fence)
-  assert.equal(content(markdownToAdf('!adf:carry{json=abc}\n')), invalid)
+  assert.equal(content(markdownToAdf('!adf:carry{json="{"}\n')), `${invalid}\\!adf: keeps the prefix literal`)
+  assert.equal(content(markdownToAdf('!adf:carry{json=abc}\n')), `${invalid}\\!adf: keeps the prefix literal`)
 })
 
 test('names the canonical spelling a carried JSON reads alone', () => {
   const canonically = "unsupported-node-shape: the opaque carry spells its node's JSON canonically: "
-  assert.equal(content(markdownToAdf('```carry\n{"type":"blockCard"}\n```\n')), `${canonically}two-space indent, keys sorted`)
+  const literal = '; \\!adf: keeps the prefix literal'
-  assert.equal(content(markdownToAdf('!adf:carry{json="{\\"type\\": \\"blockCard\\"}"}\n')), `${canonically}compact, keys sorted`)
+  assert.equal(
-  assert.equal(content(markdownToAdf('!adf:carry{json="{\\"type\\":\\"blockCard\\",\\"attrs\\":{}}"}\n')), `${canonically}compact, keys sorted`)
+    content(markdownToAdf('```adf:blockCard\n{"attrs":{}}\n```\n')),
+    `${canonically}two-space indent, keys sorted; !adf:codeBlock {language="adf:blockCard"} around a bare fence keeps it a code block`,
+  )
+  assert.equal(content(markdownToAdf('!adf:carry{json="{\\"type\\": \\"blockCard\\"}"}\n')), `${canonically}compact, keys sorted${literal}`)
+  assert.equal(content(markdownToAdf('!adf:carry{json="{\\"type\\":\\"blockCard\\",\\"attrs\\":{}}"}\n')), `${canonically}compact, keys sorted${literal}`)
 })
 
 test('names the node JSON an opaque carry restores alone', () => {
-  const node = "unsupported-node-shape: the opaque carry holds one ADF node's JSON: this JSON is no ADF node"
+  const node = "unsupported-node-shape: the opaque carry holds one ADF node's JSON: this JSON is no ADF node; "
-  assert.equal(content(markdownToAdf('```carry\n[]\n```\n')), node)
+  assert.equal(content(markdownToAdf('```adf:x\n[]\n```\n')), `${node}!adf:codeBlock {language="adf:x"} around a bare fence keeps it a code block`)
-  assert.equal(content(markdownToAdf('!adf:carry{json=null}\n')), node)
+  assert.equal(content(markdownToAdf('!adf:carry{json=null}\n')), `${node}\\!adf: keeps the prefix literal`)
-  assert.equal(content(markdownToAdf('!adf:carry{json="{\\"kind\\":\\"x\\"}"}\n')), node)
+  assert.equal(content(markdownToAdf('!adf:carry{json="{\\"kind\\":\\"x\\"}"}\n')), `${node}\\!adf: keeps the prefix literal`)
 })
 
 test('names the shape the inline carry reads alone', () => {
@@ -394,12 +428,12 @@ test('names the shape the inline carry reads alone', () => {
 
 test('holds a carried JSON value to the nesting its position leaves', () => {
   const nested = (levels: number): string => `${'['.repeat(levels)}${']'.repeat(levels)}`
-  const fence = (prefix: string, levels: number): string => `${prefix}\`\`\`carry\n${prefix}${nested(levels)}\n${prefix}\`\`\`\n`
+  const fence = (prefix: string, levels: number): string => `${prefix}\`\`\`adf:x\n${prefix}${nested(levels)}\n${prefix}\`\`\`\n`
   const deeper = (levels: number): string => `unsupported-nesting-depth: a carried node's JSON nests deeper than the ${levels} levels its position leaves`
   assert.equal(content(markdownToAdf(`!adf:carry{json="${nested(largestNesting + 2)}"}\n`)), deeper(largestNesting))
   assert.equal(
     content(markdownToAdf(fence('', largestNesting + 1))),
-    "unsupported-node-shape: the opaque carry spells its node's JSON canonically: two-space indent, keys sorted",
+    'unsupported-node-shape: the opaque carry spells its node\'s JSON canonically: two-space indent, keys sorted; !adf:codeBlock {language="adf:x"} around a bare fence keeps it a code block',
   )
   assert.equal(content(markdownToAdf(fence('> ', largestNesting + 1))), deeper(largestNesting - 1))
 })
@@ -407,11 +441,11 @@ test('holds a carried JSON value to the nesting its position leaves', () => {
 test('names the number no JSON spelling carries in an opaque carry', () => {
   const named = 'unsupported-node-shape: the opaque carry holds a number JSON cannot spell'
   assert.equal(content(markdownToAdf('!adf:carry{json="{\\"attrs\\":{\\"width\\":1e999},\\"type\\":\\"blockCard\\"}"}\n')), named)
-  assert.equal(content(markdownToAdf('```carry\n1e999\n```\n')), named)
+  assert.equal(content(markdownToAdf('```adf:x\n1e999\n```\n')), named)
 })
 
 test('names the mark spelling no opaque carry sits inside', () => {
-  const named = 'unsupported-node-shape: no mark spelling wraps an opaque carry: the carried node restores exactly, marks included'
+  const named = 'unsupported-node-shape: move the opaque carry, or the node spelling marks=empty, out of the mark spelling: it holds its own marks'
   assert.equal(content(markdownToAdf(`_a ${carried} b_\n`)), named)
   assert.equal(content(markdownToAdf(`**${carried}**\n`)), named)
   assert.equal(content(markdownToAdf(`~~a ${carried}~~\n`)), named)
@@ -454,7 +488,9 @@ test('names the marks key no marks array reads back from', () => {
   assert.equal(content(markdownToAdf('!adf:rule {marks="[1]"}\n')), named)
   assert.equal(content(markdownToAdf('!adf:rule {marks="{}"}\n')), named)
   assert.equal(content(markdownToAdf('!adf:rule {marks=x}\n')), named)
-  assert.equal(content(markdownToAdf('!adf:rule {marks="[{\\"attrs\\":{},\\"type\\":\\"em\\"}]"}\n')), named)
+  assert.equal(content(markdownToAdf('!adf:rule {marks="[{\\"type\\":\\"em\\",\\"attrs\\":{}}]"}\n')), named)
+  assert.deepEqual(content(markdownToAdf('!adf:rule {marks="[{\\"attrs\\":{},\\"type\\":\\"em\\"}]"}\n')), [{ marks: [{ attrs: {}, type: 'em' }], type: 'rule' }])
+  assert.deepEqual(content(markdownToAdf('!adf:rule {marks=empty}\n')), [{ marks: [], type: 'rule' }])
 })
 
 test('names the attribute a node holds no reading for', () => {
@@ -487,7 +523,8 @@ test('names the argument and the body a node takes no reading for', () => {
   assert.equal(content(markdownToAdf('!adf:rule x\n')), 'unsupported-node-shape: rule takes no argument: this one spells one')
   assert.equal(content(markdownToAdf('!adf:paragraph\nOne.\n\nTwo.\n!adf:/paragraph\n')), 'unsupported-node-shape: paragraph takes one paragraph as its body: this body is not one')
   assert.equal(content(markdownToAdf('!adf:paragraph\n---\n!adf:/paragraph\n')), 'unsupported-node-shape: paragraph takes one paragraph as its body: this body is not one')
-  assert.equal(content(markdownToAdf('!adf:codeBlock {wrap=true}\nx\n!adf:/codeBlock\n')), 'unsupported-node-shape: codeBlock takes one code block as its body: this body is not one')
+  assert.equal(content(markdownToAdf('!adf:codeBlock {wrap=true}\nx\n!adf:/codeBlock\n')), 'unsupported-node-shape: codeBlock takes code blocks as its body: this body holds another block')
+  assert.equal(content(markdownToAdf('!adf:codeBlock {wrap=true}\n!adf:/codeBlock\n')), 'unsupported-node-shape: codeBlock takes code blocks as its body: this body holds none')
   assert.equal(content(markdownToAdf('!adf:paragraph\n![a](/u)\n!adf:/paragraph\n')), 'unmappable-image: no ADF node carries an image inside a paragraph')
   assert.equal(content(markdownToAdf('Part !adf:date[now]{timestamp=1}.\n')), 'unsupported-node-shape: date takes no content: this one holds some')
 })
@@ -545,7 +582,7 @@ test('names the line and the offset in the input a refusal sits at, the innermos
   assert.deepEqual(position(markdownToAdf('- Part.\n- a <span>b</span>\n')), { line: 2, offset: 8 })
   assert.deepEqual(position(markdownToAdf('Part.\n\n!adf:panel info\nMore.\n')), { line: 3, offset: 7 })
   assert.deepEqual(position(markdownToAdf('x\n\na <span>b</span>\n===\n')), { line: 3, offset: 3 })
-  assert.deepEqual(position(markdownToAdf('x\n\n```carry\n{\n```\n')), { line: 3, offset: 3 })
+  assert.deepEqual(position(markdownToAdf('x\n\n```adf:x\n{\n```\n')), { line: 3, offset: 3 })
   assert.deepEqual(position(markdownToAdf('x\n\n| a |\n')), { line: 3, offset: 3 })
   assert.deepEqual(position(markdownToAdf('a\nb <span>c</span>\n')), { line: 1, offset: 0 })
   assert.deepEqual(position(markdownToAdf('Part.\r\n\r\n<div>\r\n')), { line: 3, offset: 9 })
@@ -1053,3 +1090,36 @@ test('names the directive mark left without the content it wraps', () => {
   assert.equal(content(markdownToAdf('!adf:underline[]\n')), named)
   assert.equal(content(markdownToAdf('!adf:underline{}\n')), named)
 })
+
+test('reads the text break only between two text nodes CommonMark joins, building no node', () => {
+  assert.deepEqual(content(markdownToAdf('a!adf:textBreak{}b\n')), [{ content: [text('a'), text('b')], type: 'paragraph' }])
+  assert.deepEqual(content(markdownToAdf('==a!adf:textBreak{}b==\n')), [{ content: [text('==a'), text('b==')], type: 'paragraph' }])
+  const parts = 'unsupported-node-shape: delete !adf:textBreak{} here: it stands only between two runs of text with the same formatting, which would otherwise read as one'
+  const carried = '!adf:carry{json="{\\"text\\":\\"b\\",\\"type\\":\\"text\\"}"}'
+  for (const markdown of ['!adf:textBreak{}a\n', 'a!adf:textBreak{}\n', 'a!adf:textBreak{}!adf:textBreak{}b\n', '**a**!adf:textBreak{}b\n', '[!adf:textBreak{}](/u)\n', `a!adf:textBreak{}${carried}\n`]) {
+    assert.equal(content(markdownToAdf(markdown)), parts, markdown)
+  }
+  assert.equal(content(markdownToAdf('!adf:status[a!adf:textBreak{}b]\n')), 'unsupported-node-shape: delete !adf:textBreak{} from this content slot: a slot holds one text node')
+  assert.equal(content(markdownToAdf('![a!adf:textBreak{}b](/i)\n')), 'unsupported-node-shape: delete !adf:textBreak{} from this image description: the description reads as plain alt text')
+  assert.equal(content(markdownToAdf('a!adf:textBreak{x=y}b\n')), 'unsupported-node-shape: textBreak spells the bare leaf form, !adf:textBreak{}: this one spells more')
+  assert.deepEqual(content(markdownToAdf('!adf:carry{json="{\\"type\\":\\"textBreak\\"}"}\n')), [{ content: [{ type: 'textBreak' }], type: 'paragraph' }])
+})
+
+test('leads a refusal ordinary editing meets with the edit that fixes it', () => {
+  assert.equal(
+    content(markdownToAdf('!adf:paragraph {content=empty}\nText.\n!adf:/paragraph\n')),
+    'unsupported-node-shape: remove content=empty to give the paragraph a body: content=empty holds none, and this one holds one',
+  )
+  assert.equal(
+    content(markdownToAdf('!adf:codeBlock\n```\na\n```\n```\n```\n!adf:/codeBlock\n')),
+    'unsupported-node-shape: delete the empty fence: a fence beside another holds code, and this one holds none',
+  )
+  assert.equal(
+    content(markdownToAdf('!adf:codeBlock {attrs=empty}\n```js\na\n```\n```js\nb\n```\n!adf:/codeBlock\n')),
+    "unsupported-node-shape: remove attrs=empty to give the codeBlock the fence's language: attrs=empty holds no language, and this fence names one",
+  )
+  assert.equal(
+    content(markdownToAdf('!adf:panel info {attrs=empty}\nText.\n!adf:/panel\n')),
+    'unsupported-node-shape: panel spells attrs=empty beside another attribute, an argument or a [content] slot: drop attrs=empty, or the rest',
+  )
+})

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

@@ -2,23 +2,24 @@ import type { AdfDocument, AdfNode } from '../../adf/document.ts'
 import type { Block, DirectiveBlock } from './blocks.ts'
 import type { BlockDirectiveNode } from './directive-nodes.ts'
 import type { ConvertFault } from '../../result.ts'
-import type { Flavour } from '../plain-conventions.ts'
+import type { Flavour } from '../plain/conventions.ts'
 import type { LineContainer } from '../line-container.ts'
 import type { LinkDefinitions } from './inline-content.ts'
-import { carryName, readCarriedBlock } from '../opaque-carry.ts'
+import { carryFenceType, readCarriedBlock } from '../opaque-carry.ts'
 import { commonMarkSpelling, type SpellingMemo } from '../emit/adf-to-markdown.ts'
+import { documentAttribute, documentName, documentSpelling, listBreakName, listBreakSpelling } from '../block-directive.ts'
+import { emptyKeys, nodeAttrs, nodeContent } from '../../adf/document.ts'
 import { failure, faulted, positioned, success, type ConvertErrorPath, type ParseError, type Result, type SourcePosition } from '../../result.ts'
-import { inlineLeaves } from '../emit/plain-inline.ts'
+import { inlineLeaves } from '../plain/inline-reduction.ts'
 import { languageSlot } from '../code-language.ts'
 import { largestNesting } from '../../nesting.ts'
-import { leadingMarker, readAlertMarker, readTaskMarker } from '../plain-conventions.ts'
+import { leadingMarker, readAlertMarker, readTaskMarker } from '../plain/conventions.ts'
-import { listBreakName, listBreakSpelling } from '../block-directive.ts'
+import { mintTaskIds } from '../plain/task-ids.ts'
-import { mintTaskIds } from './task-ids.ts'
-import { nodeAttrs, nodeContent } from '../../adf/document.ts'
 import { parseBlocks } from './blocks.ts'
 import { parseInlineContent } from './inline-content.ts'
 import { readBlockDirectiveNode } from './directive-nodes.ts'
-import { unsupportedNodeShape } from '../directive-syntax.ts'
+import { spellStringAttribute, unsupportedNodeShape } from '../directive-syntax.ts'
+import { spellsEmpty } from '../empty-keys.ts'
 
 type Paragraph = Extract<Block, { kind: 'paragraph' }>
 
@@ -39,10 +40,15 @@ export function plainMarkdownToAdf(markdown: string): Result<AdfDocument, ParseE
 
 function readDocument(markdown: string, flavour: Flavour): Result<AdfDocument, ParseError> {
   const parsed = parseBlocks(markdown)
+  const [only] = parsed.blocks
+  if (parsed.blocks.length === 1 && only?.kind === 'directive' && only.name === documentName) {
+    const fault = documentFault(only)
+    return fault === undefined ? success({ type: 'doc', version: 1 }) : positioned(faulted(fault, []), only.position)
+  }
   const reading: Reading = { carried: new Set(), definitions: parsed.definitions, flavour, inExpand: false, memo: new Map() }
   const content = positioned(readBlocks(parsed.blocks, reading, [], 0), documentStart)
   if (!content.ok) return content
-  const document: AdfDocument = content.value.length === 0 ? { type: 'doc', version: 1 } : { content: content.value, type: 'doc', version: 1 }
+  const document: AdfDocument = { content: content.value, type: 'doc', version: 1 }
   if (flavour === 'plain') mintTaskIds(document, markdown, reading.carried)
   return success(document)
 }
@@ -52,6 +58,10 @@ function readBlocks(blocks: readonly Block[], reading: Reading, path: ConvertErr
   const content: AdfNode[] = []
   for (const [index, block] of blocks.entries()) {
     const nodePath = [...path, 'content', content.length]
+    if (block.kind === 'directive' && block.name === documentName) {
+      const fault = documentFault(block) ?? unsupportedNodeShape(`delete the ${documentSpelling} line to give the document content: it stands only as the whole document`)
+      return positioned(faulted(fault, nodePath), block.position)
+    }
     if (block.kind === 'directive' && block.name === listBreakName) {
       const fault = listBreakFault(block, blocks[index - 1], blocks[index + 1])
       if (fault !== undefined) return positioned(faulted(fault, nodePath), block.position)
@@ -73,6 +83,15 @@ function listBreakFault(block: DirectiveBlock, previous: Block | undefined, next
   return previous.kind === next?.kind ? undefined : partsFault()
 }
 
+function documentFault(block: DirectiveBlock): ConvertFault | undefined {
+  const spelled = block.attributes.get(documentAttribute.key)
+  if (block.argument === undefined && block.attributes.size === 1 && spelled?.spelling === documentAttribute.value) return undefined
+  if (block.argument === undefined && block.attributes.size === 1 && spellsEmpty(spelled)) {
+    return unsupportedNodeShape(`an empty document is empty markdown, and ${documentSpelling} spells a document holding no content key: this one spells ${documentAttribute.key}=empty`)
+  }
+  return unsupportedNodeShape(`${documentName} spells the one form ${documentSpelling}: this one spells another`)
+}
+
 function partsFault(): ConvertFault {
   return unsupportedNodeShape(`${listBreakName} parts two adjacent lists of one type: this one parts something else`)
 }
@@ -216,22 +235,38 @@ function directiveNode(block: DirectiveBlock, reading: Reading, path: ConvertErr
 function directiveBody(read: BlockDirectiveNode, blocks: Block[] | undefined, reading: Reading, path: ConvertErrorPath, depth: number): Result<AdfNode> {
   const { contentModel, node } = read
   if (blocks === undefined) return success(node)
+  // A directive builds a content key only from content=empty, which holds no body.
+  if (node.content !== undefined) return blocks.length === 0 ? success(node) : failure('unsupported-node-shape', `remove content=empty to give the ${node.type} a body: content=empty holds none, and this one holds one`, path)
   if (contentModel === 'code') return codeDirectiveNode(node, blocks, path)
   if (contentModel === 'inline') return inlineBodyNode(node, blocks, reading, path)
   return containerNode(node, blocks, reading, path, depth)
 }
 
+// spec/flavour.md, The CommonMark blocks: one fence per text node, every fence carrying the one language.
 function codeDirectiveNode(node: AdfNode, blocks: readonly Block[], path: ConvertErrorPath): Result<AdfNode> {
-  const only = blocks.length === 1 ? blocks[0] : undefined
+  const fences: Extract<Block, { kind: 'code' }>[] = []
-  if (only?.kind !== 'code') return failure('unsupported-node-shape', `${node.type} takes one code block as its body: this body is not one`, path)
+  for (const block of blocks) {
+    if (block.kind !== 'code') return failure('unsupported-node-shape', `${node.type} takes code blocks as its body: this body holds another block`, path)
+    fences.push(block)
+  }
+  const [first] = fences
+  if (first === undefined) return failure('unsupported-node-shape', `${node.type} takes code blocks as its body: this body holds none`, path)
+  if (fences.some((fence) => fence.language !== first.language)) return failure('unsupported-node-shape', `${node.type} holds one language, so its fences carry one info string: these differ`, path)
+  if (fences.length > 1 && fences.some((fence) => fence.text === '')) return failure('unsupported-node-shape', `delete the empty fence: a fence beside another holds code, and this one holds none`, path)
   const attribute = nodeAttrs(node)['language']
-  const fromFence = only.language !== ''
+  const fromFence = first.language !== ''
-  const slot = languageSlot(fromFence ? only.language : attribute)
+  const slot = languageSlot(fromFence ? first.language : attribute)
+  if (!fromFence && slot.kind === 'fence') {
+    return failure('unsupported-node-shape', `move language=${spellStringAttribute(slot.info)} to the fences' info strings: they can spell this language`, path)
+  }
   if ((slot.kind === 'fence') !== fromFence || (fromFence && attribute !== undefined)) {
     return failure('unsupported-node-shape', `${node.type} spells its language in the fence info string, or in the attribute where no info string carries it back`, path)
   }
-  const spelled = fromFence ? { ...node, attrs: { ...node.attrs, language: only.language } } : node
+  if (fromFence && emptyKeys(node).includes('attrs')) {
-  return success(withContent(spelled, only.text === '' ? [] : [{ text: only.text, type: 'text' }]))
+    return failure('unsupported-node-shape', `remove attrs=empty to give the ${node.type} the fence's language: attrs=empty holds no language, and this fence names one`, path)
+  }
+  const spelled = fromFence ? { ...node, attrs: { ...node.attrs, language: first.language } } : node
+  return success(withContent(spelled, first.text === '' ? [] : fences.map((fence): AdfNode => ({ text: fence.text, type: 'text' }))))
 }
 
 function tableNode(rows: readonly string[][], reading: Reading, path: ConvertErrorPath): Result<AdfNode> {
@@ -278,8 +313,9 @@ function listNode(node: AdfNode, items: readonly Block[][], reading: Reading, pa
 }
 
 function codeBlockNode(language: string, text: string, reading: Reading, path: ConvertErrorPath, depth: number): Result<AdfNode> {
-  if (language === carryName) {
+  const carriedType = carryFenceType(language)
-    const carried = readCarriedBlock(text, depth)
+  if (carriedType !== undefined) {
+    const carried = readCarriedBlock(carriedType, text, depth)
     if (carried.fault !== undefined) return faulted(carried.fault, path)
     reading.carried.add(carried.value)
     return success(carried.value)

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

@@ -3,10 +3,9 @@ import test from 'node:test'
 
 import type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from '../../adf/document.ts'
 import { adfToMarkdown } from '../emit/adf-to-markdown.ts'
-import { adfToPlainMarkdown } from '../emit/plain-reduction.ts'
+import { adfToPlainMarkdown } from '../plain/adf-to-plain-markdown.ts'
 import { largestNesting } from '../../nesting.ts'
 import { markdownToAdf, plainMarkdownToAdf } from './markdown-to-adf.ts'
-import { toEditorNormal } from '../../adf/editor-normal.ts'
 
 const code: AdfMark = { type: 'code' }
 const em: AdfMark = { type: 'em' }
@@ -18,7 +17,7 @@ const taskTypes = ['blockTaskItem', 'taskItem', 'taskList']
 function read(markdown: string): readonly AdfNode[] | string {
   const parsed = plainMarkdownToAdf(markdown)
   if (!parsed.ok) return parsed.error.code
-  const blocks = toEditorNormal(parsed.value).content ?? []
+  const blocks = parsed.value.content ?? []
   const pending = [...blocks]
   for (let block = pending.pop(); block !== undefined; block = pending.pop()) {
     for (const child of block.content ?? []) pending.push(child)
@@ -31,10 +30,6 @@ function read(markdown: string): readonly AdfNode[] | string {
   return blocks
 }
 
-function normal(...blocks: AdfNode[]): readonly AdfNode[] {
-  return toEditorNormal(document(...blocks)).content ?? []
-}
-
 function document(...content: AdfNode[]): AdfDocument {
   return { content, type: 'doc', version: 1 }
 }
@@ -57,7 +52,7 @@ function bare(type: string, ...content: AdfNode[]): AdfNode {
 }
 
 function paragraph(...content: AdfNode[]): AdfNode {
-  return bare('paragraph', ...content)
+  return content.length === 0 ? { type: 'paragraph' } : bare('paragraph', ...content)
 }
 
 function said(value: string): AdfNode {
@@ -101,7 +96,7 @@ test('reads the rest of an alert marker line as the panel first body paragraph,
   assert.deepEqual(read('> [!tip] Title\n> body\n'), [panel('tip', said('Title'), said('body'))])
   assert.deepEqual(read('> [!tip] Title\\\n> body\n'), [panel('tip', said('Title'), said('body'))])
   assert.deepEqual(read('> [!NOTE]\\\n> Broken.\n'), [panel('info', said('Broken.'))])
-  assert.deepEqual(read('> [!NOTE]\n'), normal(panel('info', paragraph())))
+  assert.deepEqual(read('> [!NOTE]\n'), [panel('info', paragraph())])
   assert.deepEqual(read('> > [!WARNING]\n> > Inner.\n'), [bare('blockquote', panel('warning', said('Inner.')))])
 })
 
@@ -120,27 +115,27 @@ test('reads a folded callout to an expand titled by the rest of its marker line,
     node('expand', { title: 'Why?' }, paragraph(text('See '), text('the docs', link), text(', '), text('now', strong), text('.'))),
   ])
   assert.deepEqual(read('> [!NOTE]- Two\\\n> lines\n'), [node('expand', { title: 'Two' }, said('lines'))])
-  assert.deepEqual(read('> [!faq]- See [x](http://y)\n'), normal(node('expand', { title: 'See x (http://y)' }, paragraph())))
+  assert.deepEqual(read('> [!faq]- See [x](http://y)\n'), [node('expand', { title: 'See x (http://y)' }, paragraph())])
-  assert.deepEqual(read('> [!faq]- [a **b**](u "t")[c](u) and [d](v)\n'), normal(node('expand', { title: 'a bc (u) and d (v)' }, paragraph())))
+  assert.deepEqual(read('> [!faq]- [a **b**](u "t")[c](u) and [d](v)\n'), [node('expand', { title: 'a bc (u) and d (v)' }, paragraph())])
-  assert.deepEqual(read('> [!faq]- <http://y> or <a@b.c> or <http://a\\b>\n'), normal(node('expand', { title: 'http://y or a@b.c or http://a\\b' }, paragraph())))
+  assert.deepEqual(read('> [!faq]- <http://y> or <a@b.c> or <http://a\\b>\n'), [node('expand', { title: 'http://y or a@b.c or http://a\\b' }, paragraph())])
-  assert.deepEqual(read('> [!faq]- [a&#10;b](u)\n'), normal(node('expand', { title: 'a\nb (u)' }, paragraph())))
+  assert.deepEqual(read('> [!faq]- [a&#10;b](u)\n'), [node('expand', { title: 'a\nb (u)' }, paragraph())])
-  assert.deepEqual(read('> [!faq]- [!adf:mention[@M]{id=5}](u) !adf:inlineCard{url="http://y"}\n'), normal(node('expand', { title: '@M (u) http://y' }, paragraph())))
+  assert.deepEqual(read('> [!faq]- [!adf:mention[@M]{id=5}](u) !adf:inlineCard{url="http://y"}\n'), [node('expand', { title: '@M (u) http://y' }, paragraph())])
-  assert.deepEqual(read('> [!NOTE]- Set ==x== here\n'), normal(node('expand', { title: 'Set ==x== here' }, paragraph())))
+  assert.deepEqual(read('> [!NOTE]- Set ==x== here\n'), [node('expand', { title: 'Set ==x== here' }, paragraph())])
   assert.deepEqual(read('> [!NOTE]-\n>\n> Line.\n'), [bare('expand', said('Line.'))])
 })
 
 test('reads a folded callout inside an expand to a nested expand', () => {
   const markdown = '> [!NOTE]- Outer\n>\n> > [!NOTE]- Inner\n> >\n> > Deep.\n>\n> > [!TIP]\n> >\n> > > [!NOTE]-\n'
-  assert.deepEqual(read(markdown), normal(node('expand', { title: 'Outer' }, node('nestedExpand', { title: 'Inner' }, said('Deep.')), panel('tip', bare('nestedExpand', paragraph())))))
+  assert.deepEqual(read(markdown), [node('expand', { title: 'Outer' }, node('nestedExpand', { title: 'Inner' }, said('Deep.')), panel('tip', bare('nestedExpand', paragraph())))])
-  assert.deepEqual(read('- > [!NOTE]-\n'), normal(bare('bulletList', bare('listItem', bare('expand', paragraph())))))
+  assert.deepEqual(read('- > [!NOTE]-\n'), [bare('bulletList', bare('listItem', bare('expand', paragraph())))])
-  assert.deepEqual(read('!adf:expand\n> [!NOTE]- Inner\n!adf:/expand\n'), normal(bare('expand', node('nestedExpand', { title: 'Inner' }, paragraph()))))
+  assert.deepEqual(read('!adf:expand\n> [!NOTE]- Inner\n!adf:/expand\n'), [bare('expand', node('nestedExpand', { title: 'Inner' }, paragraph()))])
 })
 
 test('reads a bullet list whose every item leads with a task marker to a task list', () => {
   assert.deepEqual(read('- [x] Write the spec\n- [ ] Ship **it**\n- [X] Tell\n'), [
     bare('taskList', task('DONE', text('Write the spec')), task('TODO', text('Ship '), text('it', strong)), task('DONE', text('Tell'))),
   ])
-  assert.deepEqual(read('- [x]\n- [ ]\\\n  after\n'), normal(bare('taskList', task('DONE'), task('TODO', text('after')))))
+  assert.deepEqual(read('- [x]\n- [ ]\\\n  after\n'), [bare('taskList', task('DONE'), task('TODO', text('after')))])
   const minted = plainMarkdownToAdf('- [x] Parent\n  - [ ] Child\n')
   assert.deepEqual(minted.ok ? minted.value.content : minted.error.code, [
     node(
@@ -202,7 +197,7 @@ test('reads what the reduction wrote back to the node it reduced, less the attri
     assert.deepEqual(roundTripped(node('panel', { localId, panelType }, said('Check.'))), [panel(panelType, said('Check.'))], panelType)
   }
   const expand = node('expand', { localId, title: 'Log' }, said('Line.'), node('nestedExpand', { title: 'Inner' }, said('Deep.')))
-  assert.deepEqual(roundTripped(node('panel', { panelType: 'tip' }, paragraph()), node('expand', { title: 'Empty' }, paragraph())), normal(panel('tip', paragraph()), node('expand', { title: 'Empty' }, paragraph())))
+  assert.deepEqual(roundTripped(node('panel', { panelType: 'tip' }, paragraph()), node('expand', { title: 'Empty' }, paragraph())), [panel('tip', paragraph()), node('expand', { title: 'Empty' }, paragraph())])
   assert.deepEqual(roundTripped(expand), [node('expand', { title: 'Log' }, said('Line.'), node('nestedExpand', { title: 'Inner' }, said('Deep.')))])
   const tasks = bare(
     'taskList',
@@ -266,3 +261,8 @@ test('keeps what markdownToAdf reads that no row reads, and refuses only what it
   for (let level = 0; level < largestNesting; level += 1) deep = `> ${deep}`
   assert.equal(typeof read(deep), 'object')
 })
+
+test('joins a carried text node to no neighbour, inside a highlight too', () => {
+  const carried = '!adf:carry{json="{\\"marks\\":[],\\"text\\":\\"b\\",\\"type\\":\\"text\\"}"}'
+  assert.deepEqual(read(`==a${carried}==\n`), [paragraph(text('a', highlight), { marks: [], text: 'b', type: 'text' })])
+})

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

@@ -2,7 +2,7 @@ import assert from 'node:assert/strict'
 import test from 'node:test'
 
 import type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from '../../adf/document.ts'
-import { adfToPlainMarkdown, reduceToPlain } from './plain-reduction.ts'
+import { adfToPlainMarkdown, reduceToPlain } from './adf-to-plain-markdown.ts'
 import { largestNesting } from '../../nesting.ts'
 
 const code: AdfMark = { type: 'code' }
@@ -64,6 +64,7 @@ test('refuses what the document guard refuses, and nothing else', () => {
   let deep: AdfNode = said('x')
   for (let level = 0; level <= largestNesting; level += 1) deep = { content: [deep], type: 'layoutColumn' }
   assert.match(plainDocument(document(deep)), /^unsupported-nesting-depth at \/content\/0(\/content\/0)+$/)
+  assert.match(plainDocument(document(paragraph(text('a'), text('b')), text('c'), text('d'), deep)), /^unsupported-nesting-depth at \/content\/3(\/content\/0)+$/)
   let deepInline: AdfNode = text('x')
   for (let level = 0; level <= largestNesting; level += 1) deepInline = { content: [deepInline], type: 'unknownInline' }
   assert.match(plainDocument(document(paragraph(deepInline))), /^unsupported-nesting-depth at /)
@@ -177,7 +178,7 @@ test('keeps the CommonMark blocks in their spelling and drops their attributes a
   assert.equal(plain(node('paragraph', localId, text('x')), node('heading', { level: 2, localId: '01a0d99b-1f57-7fec-94ae-50c2ee25c9de' }, text('h'))), 'x\n\n## h\n')
   assert.equal(plain({ attrs: localId, content: [said('q')], marks: [{ type: 'breakout' }], type: 'blockquote' }), '> q\n')
   assert.equal(plain(node('codeBlock', { language: 'ts', wrap: true }, text('a\r\nb\u0000'))), '```ts\na\nb\n```\n')
-  assert.equal(plain(node('codeBlock', { language: 'carry' }, text('a'), { type: 'hardBreak' }, text('b', strong))), '```\na\nb\n```\n')
+  assert.equal(plain(node('codeBlock', { language: 'adf:x' }, text('a'), { type: 'hardBreak' }, text('b', strong))), '```\na\nb\n```\n')
   assert.equal(plain(node('codeBlock', {})), '```\n```\n')
   assert.equal(plain(node('rule', { color: '#000' })), '---\n')
   assert.equal(plain(node('orderedList', { localId: '01a0d99b-1f58-7b95-829b-6f9860371d54', order: 3 }, item(said('c')))), '3. c\n')
@@ -337,3 +338,9 @@ test('keeps the nodes the plain flavour spells and degrades only what it cannot'
   const reduced = reduceToPlain(document(node('panel', { localId: '01a0d99b-1f56-7a50-889a-f4375f09ee05', panelType: 'info' }, said('x')), tasks))
   assert.deepEqual(reduced.ok ? reduced.value : undefined, document(node('panel', { panelType: 'info' }, said('x')), { content: [node('taskItem', { state: 'DONE' }, text('t'))], type: 'taskList' }))
 })
+
+test('writes what the editor-normal form of the document writes', () => {
+  assert.equal(plain({ attrs: { order: -0 }, content: [{ content: [], type: 'listItem' }], type: 'orderedList' }), '0.\n')
+  assert.equal(plain({ content: [], text: 'hi', type: 'futureInline' }), 'hi\n')
+  assert.equal(plain(paragraph({ marks: [{ attrs: {}, type: 'code' }], text: 'a', type: 'text' }, { marks: [{ type: 'code' }], text: '|b', type: 'text' })), '`a|b`\n')
+})

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

@@ -1,13 +1,14 @@
 import type { AdfDocument, AdfNode } from '../../adf/document.ts'
 import { adfDocumentFault, nodeAttrs, nodeContent } from '../../adf/document.ts'
-import { commonMarkSpelling, largestListMarker, writeMarkdown, type SpellingMemo } from './adf-to-markdown.ts'
+import { commonMarkSpelling, largestListMarker, writeMarkdown, type SpellingMemo } from '../emit/adf-to-markdown.ts'
 import { blockNodeModel } from '../../adf/block-nodes.ts'
 import { failure, faulted, success, type ConvertErrorPath, type Result } from '../../result.ts'
-import { inlineLeaves, isBlockNodeType, oneLine, reduceInline, writableHref } from './plain-inline.ts'
+import { inlineLeaves, isBlockNodeType, oneLine, reduceInline, writableHref } from './inline-reduction.ts'
 import { inlineNodeModel } from '../../adf/inline-nodes.ts'
 import { languageSlot } from '../code-language.ts'
 import { largestNesting } from '../../nesting.ts'
-import { taskMarker } from '../plain-conventions.ts'
+import { taskMarker } from './conventions.ts'
+import { toEditorNormal } from './editor-normal.ts'
 
 // depth: the level the node reduced stands at, counted as the emitter counts it.
 type Reduction = { depth: number; memo: SpellingMemo; path: ConvertErrorPath }
@@ -50,8 +51,14 @@ export function reduceToPlain(document: AdfDocument): Result<AdfDocument> {
   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 = reduceBlocks(nodeContent(document), { depth: 0, memo: new Map(), path: [] })
+  // docs/decisions.md §Equality is deep: the reduction reads and writes editor-normal ADF.
-  return blocks.ok ? success({ content: blocks.value, type: 'doc', version: 1 }) : blocks
+  const blocks = reduceBlocks(nodeContent(toEditorNormal(document)), { depth: 0, memo: new Map(), path: [] })
+  if (!blocks.ok) {
+    // Merging text renumbers siblings, so a refusal's path comes from the caller's document.
+    const raw = reduceBlocks(nodeContent(document), { depth: 0, memo: new Map(), path: [] })
+    return !raw.ok && raw.error.code === blocks.error.code ? raw : blocks
+  }
+  return success(toEditorNormal({ content: blocks.value, type: 'doc', version: 1 }))
 }
 
 function reduceBlocks(nodes: readonly AdfNode[], reduction: Reduction): Result<AdfNode[]> {
@@ -84,7 +91,7 @@ function reduceStanding(node: AdfNode, reduction: Reduction): Result<AdfNode[]>
 
 function standsInline(node: AdfNode): boolean {
   if (node.type === 'text' || inlineNodeModel(node.type) !== undefined) return true
-  return !isBlockNodeType(node.type) && node.content === undefined
+  return !isBlockNodeType(node.type) && nodeContent(node).length === 0
 }
 
 function reduceBody(node: AdfNode, reduction: Reduction): Result<AdfNode[]> {
@@ -262,7 +269,8 @@ function listItem(blocks: Result<AdfNode[]>): Result<AdfNode[]> {
 // A list item's first line reads as no rule and holds no line of spaces alone: the rule and the spaces give way.
 function itemOf(blocks: readonly AdfNode[]): AdfNode {
   const rules = blocks.findIndex((block) => block.type !== 'rule')
-  return { content: blankedCode(blocks.slice(rules === -1 ? blocks.length : rules)), type: 'listItem' }
+  const content = blankedCode(blocks.slice(rules === -1 ? blocks.length : rules))
+  return content.length === 0 ? { type: 'listItem' } : { content, type: 'listItem' }
 }
 
 function blankedCode(blocks: readonly AdfNode[]): AdfNode[] {

src/markdown/plain/conventions.ts

@@ -1,4 +1,4 @@
-import { isWordCharacter } from './commonmark/emphasis-matching.ts'
+import { isWordCharacter } from '../commonmark/emphasis-matching.ts'
 
 export type Flavour = 'lossless' | 'plain'
 

src/markdown/plain/editor-normal.test.ts

@@ -1,8 +1,8 @@
 import assert from 'node:assert/strict'
 import test from 'node:test'
 
-import type { AdfNode } from './document.ts'
+import type { AdfNode } from '../../adf/document.ts'
-import type { JsonValue } from '../json-value.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', () => {
@@ -50,14 +50,15 @@ test('reads negative zero as zero, as JSON does', () => {
   )
 })
 
-test('reads an empty attrs object, marks array or content array as the absent key', () => {
+test('reads an empty attrs object, marks array or content array as the absent key, but on doc', () => {
   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 })
+  assert.deepEqual(toEditorNormal({ content: [], type: 'doc', version: 1 }), { content: [], type: 'doc', version: 1 })
+  assert.deepEqual(toEditorNormal({ type: 'doc', version: 1 }), { type: 'doc', version: 1 })
 })
 
 test('normalizes blocks and mark attributes nesting far past the levels a recursive walk survives', () => {
@@ -75,3 +76,8 @@ test('normalizes blocks and mark attributes nesting far past the levels a recurs
   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'])
 })
+
+test('joins a text node holding content to its neighbour, as editor-normal forms hold no content to part them', () => {
+  const paragraph: AdfNode = { content: [{ content: [{ text: 'lost', type: 'text' }], text: 'a', type: 'text' }, { text: 'b', type: 'text' }], type: 'paragraph' }
+  assert.deepEqual(toEditorNormal({ content: [paragraph], type: 'doc', version: 1 }).content, [{ content: [{ content: [{ text: 'lost', type: 'text' }], text: 'ab', type: 'text' }], type: 'paragraph' }])
+})

src/markdown/plain/editor-normal.ts

@@ -1,34 +1,26 @@
-import type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from './document.ts'
+import type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from '../../adf/document.ts'
-import type { JsonValue } from '../json-value.ts'
+import type { JsonValue } from '../../json-value.ts'
-import { nodeAttrs, nodeContent, nodeMarks } from './document.ts'
+import { identicalMark, mergeAdjacentText, nodeAttrs, nodeContent, nodeMarks } from '../../adf/document.ts'
-import { serializeCanonicalJson } from '../canonical-json.ts'
+import { joinsWhenRead } from '../adjacent-text.ts'
 
 type JsonContainer = JsonValue[] | { [key: string]: JsonValue }
 
 type NodeHolder = { content?: AdfNode[] }
 
-export function sameMark(candidate: AdfMark, mark: AdfMark): boolean {
+// The editor's rule is the reader's over the pair's editor-normal forms, which hold no content: a text node's content never parts it.
-  return markKey(candidate) === markKey(mark)
+export function joinsWhenEditorNormal(previous: AdfNode, node: AdfNode): boolean {
+  return joinsWhenRead(normalNode(previous), normalNode(node))
 }
 
-export function mergeAdjacentText(nodes: readonly AdfNode[]): AdfNode[] {
+export function sameMarkWhenEditorNormal(left: AdfMark, right: AdfMark): boolean {
-  const merged: AdfNode[] = []
+  return identicalMark(normalMark(left), normalMark(right))
-  for (const node of nodes) {
-    const previous = merged[merged.length - 1]
-    if (previous !== undefined && mergesText(previous) && mergesText(node) && sameMarks(previous, node)) {
-      merged[merged.length - 1] = { ...previous, text: `${previous.text ?? ''}${node.text ?? ''}` }
-      continue
-    }
-    merged.push(node)
-  }
-  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))
+    const content = mergeAdjacentText(nodeContent(entry.source), joinsWhenEditorNormal)
     if (content.length === 0) continue
     entry.holder.content = content.map((source) => {
       const holder = normalNode(source)
@@ -36,6 +28,8 @@ export function toEditorNormal(document: AdfDocument): AdfDocument {
       return holder
     })
   }
+  // ADF's schema requires content on doc, so an empty one stays.
+  if (document.content !== undefined && normal.content === undefined) normal.content = []
   return normal
 }
 
@@ -72,19 +66,3 @@ function normalValue(value: JsonValue, pending: JsonContainer[]): JsonValue {
   pending.push(copy)
   return copy
 }
-
-function mergesText(node: AdfNode): boolean {
-  return node.type === 'text' && Object.keys(nodeAttrs(node)).length === 0
-}
-
-export function sameMarks(previous: AdfNode, node: AdfNode): boolean {
-  return marksKey(nodeMarks(previous)) === marksKey(nodeMarks(node))
-}
-
-function marksKey(marks: readonly AdfMark[]): string {
-  return marks.map(markKey).join('\n')
-}
-
-function markKey(mark: AdfMark): string {
-  return `${mark.type} ${serializeCanonicalJson(nodeAttrs(mark), 'compact')}`
-}