README.md

@@ -118,18 +118,22 @@ Plain markdown is a second flavour of the same grammar. `adfToPlainMarkdown` wri
 tools render — GitHub, GitLab, Obsidian and the like — keeping the content and dropping the rest:
 attributes, colours, layout, identity. It refuses only
 `not-an-adf-document`, `unsupported-document-version` and `unsupported-nesting-depth`, and writes
-no directive. `plainMarkdownToAdf` reads through `markdownToAdf`, refusing what it refuses, and
+no directive.
-turns the conventions below back into nodes, taking other tools' spellings too. Markdown
+
-`adfToPlainMarkdown` wrote reads back and writes again byte for byte; the document it came from
+`plainMarkdownToAdf` reads what `markdownToAdf` reads and refuses what it refuses, and reads the
-does not come back. To edit a document and save it back, use `adfToMarkdown` and `markdownToAdf`:
+conventions below as nodes, taking other tools' spellings too; a backslash keeps a marker as text:
-saving what this pair read replaces mentions, attachments and macros with text.
+`\==x==`, `> \[!NOTE]`, `- \[x]`. Markdown `adfToPlainMarkdown` wrote reads back and writes again
+byte for byte; the document it came from does not come back.
+
+To edit a document and save it back, use `adfToMarkdown` and `markdownToAdf`: saving what this pair
+read replaces mentions, attachments and macros with text.
 
 | ADF | Written | Read back |
 | --- | --- | --- |
-| `panel` | a GitHub alert, `> [!WARNING]`: info `NOTE`, note `IMPORTANT`, tip and success `TIP`, warning `WARNING`, error `CAUTION`, custom `NOTE` | GitHub's five words, and Obsidian's: hint tip; success, check, done success; attention warning; danger, failure, fail, missing, bug, error error; any other word info — in any case |
+| `panel` | a GitHub alert, `> [!WARNING]`: info `NOTE`, note `IMPORTANT`, tip and success `TIP`, warning `WARNING`, error `CAUTION`, custom `NOTE` | `NOTE` info, `IMPORTANT` note, `TIP` tip, `WARNING` warning, `CAUTION` error, and Obsidian's: hint tip; success, check, done success; attention warning; danger, failure, fail, missing, bug, error error; any other word info — in any case; the rest of the marker's line is the first paragraph |
-| `expand`, `nestedExpand` | Obsidian's folded callout, `> [!NOTE]- Title` | `-` or `+` after any word; an expand inside an expand is a `nestedExpand` |
+| `expand`, `nestedExpand` | Obsidian's folded callout, `> [!NOTE]- Title` | `-` or `+` after any word, the rest of the marker's line the title; an expand inside an expand is a `nestedExpand` |
 | `taskList` | `- [x] Done`, `- [ ] Todo` | a bullet list whose every item is so marked, `[X]` too |
-| `backgroundColor` | `==text==` | `==text==` bounded outside by whitespace, punctuation or a line edge, in the editor's default highlight |
+| `backgroundColor` | `==text==` | `==text==` on one line, the text touching both delimiters, bounded outside by whitespace, punctuation or a line edge, in the editor's default highlight `#f8e6a0` |
 | `table` | a pipe table: the first row its header, a cell's blocks on one line, a span kept under its header by empty cells | — |
 | `decisionList` | a bullet list | — |
 | `mention`, `status`, `emoji`, `date` | their text: `@` kept, a mention with none `@` and its id, an emoji its `shortName` without, a date `2026-09-13` in UTC | — |
@@ -142,10 +146,11 @@ saving what this pair read replaces mentions, attachments and macros with text.
 - Content the document only references leaves an italic note naming it where it stood:
   `_(image not included)_`, `_(jira-issues-table not included)_`, `_(synced block not included)_`,
   `_(link card not included)_`, `_(extension not included)_`.
-- `code`, `em`, `link`, `strike` and `strong` stay; every other mark drops, keeping its text, and
+- `backgroundColor`, `code`, `em`, `link`, `strike` and `strong` stay; every other mark drops,
-  so does a mark CommonMark cannot spell where it stands.
+  keeping its text, and so does a mark CommonMark cannot spell where it stands.
-- A newline in text is a hard break, edge whitespace outside a link or code span is trimmed,
+- A newline in text is a hard break and in an expand's title a space, edge whitespace outside a
-  carriage returns and null characters are removed, and an empty paragraph drops.
+  link or code span is trimmed, carriage returns and null characters are removed, and an empty
+  paragraph drops.
 - An ordered list numbered past `999999999`, or adjacent ordered lists whose numbering does not
   continue, is one bullet list keeping its numbers as text.
 - A node read back carries no `localId`, which Atlassian's schema requires on `taskList`,

docs/decisions.md

@@ -304,8 +304,8 @@ input reads `message`.
   inline alike, `\|` for every pipe row.
 - `not-an-adf-document` carries the document's own path throughout: seven of the guard's eight
   branches read the document's own shape, and threading a path to the eighth — a malformed node
-  anywhere in the tree — wants the manual stack §Nothing recurses unbounded forces, whose empty
+  anywhere in the tree — wants the manual stack §Nothing recurses unbounded forces. The message
-  half no input reaches. The message names the violation instead.
+  names the violation instead.
 
 ## Publish on a version bump
 

src/conformance/adf-property.test.ts

@@ -6,8 +6,7 @@ import { adfDocument, propertyRuns, propertyTimeout } from './property-harness.t
 import { adfToMarkdown } from '../markdown/emit/adf-to-markdown.ts'
 import { adfToPlainMarkdown } from '../markdown/emit/plain-reduction.ts'
 import { directivePrefix } from '../markdown/directive-syntax.ts'
-import { markdownToAdf } from '../markdown/parse/markdown-to-adf.ts'
+import { markdownToAdf, plainMarkdownToAdf } from '../markdown/parse/markdown-to-adf.ts'
-import { plainMarkdownToAdf } from '../markdown/parse/plain-lift.ts'
 import { toEditorNormal } from '../adf/editor-normal.ts'
 
 const gateRuns = 1600

src/index.ts

@@ -4,5 +4,4 @@ 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 { isAdfDocument } from './adf/document.ts'
-export { markdownToAdf } from './markdown/parse/markdown-to-adf.ts'
+export { markdownToAdf, plainMarkdownToAdf } from './markdown/parse/markdown-to-adf.ts'
-export { plainMarkdownToAdf } from './markdown/parse/plain-lift.ts'

src/markdown/emit/plain-reduction.test.ts

@@ -118,7 +118,7 @@ test('spells an expand and a nested expand as a folded callout titled by the mar
     '> [!NOTE]- Build log\n>\n> Line.\n>\n> > [!NOTE]- Inner\n> >\n> > Deep.\n',
   )
   assert.equal(plain(node('expand', {}, said('Line.'))), '> [!NOTE]-\n>\n> Line.\n')
-  assert.equal(plain(node('expand', { title: ' *Two*\nlines ' })), '> [!NOTE]- \\*Two\\*\\\n> lines\n')
+  assert.equal(plain(node('expand', { title: ' *Two*\nlines ' })), '> [!NOTE]- \\*Two\\* lines\n')
 })
 
 test('spells a task list as a bullet list whose items lead with their state', () => {

src/markdown/emit/plain-reduction.ts

@@ -190,7 +190,7 @@ function quoted(head: Result<AdfNode[]>, node: AdfNode, reduction: Reduction): R
 
 function reduceExpand(node: AdfNode, reduction: Reduction): Result<AdfNode[]> {
   const title = nodeAttrs(node)['title']
-  const marker = typeof title === 'string' ? `${foldedAlertMarker} ${title.replace(/^[ \t\n\r]+/, '')}` : foldedAlertMarker
+  const marker = typeof title === 'string' ? `${foldedAlertMarker} ${title.replace(/^[ \t\n\r]+/, '').replaceAll('\n', ' ')}` : foldedAlertMarker
   return quoted(paragraphOf([text(marker)], { ...reduction, depth: reduction.depth + 1 }), node, reduction)
 }
 

src/markdown/parse/inline-content.ts

@@ -1,15 +1,17 @@
 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 { LineContainer } from '../line-container.ts'
 import type { LinkDefinition } from '../commonmark/link-syntax.ts'
 import { backslashEscape, decodeTextEscapes, inlineHtmlConstruct, readBracketedAutolink, readEmailAutolink, trimTrailingSpace } from '../commonmark/grammar.ts'
 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 { delimiterFlags, isWordCharacter, matchEmphasis, runLength } from '../commonmark/emphasis-matching.ts'
+import { highlightDelimiter } from '../plain-conventions.ts'
 import { failure, faulted, success, type ConvertErrorPath, type Result } from '../../result.ts'
 import { inlineNodeModel } from '../../adf/inline-nodes.ts'
-import { mergeAdjacentText } from '../../adf/editor-normal.ts'
+import { mergeAdjacentText, sameMarks } from '../../adf/editor-normal.ts'
 import { noSpans, readInlineDirective } from '../directive-syntax.ts'
 import { nodeAttrs, nodeMarks } from '../../adf/document.ts'
 import { normalizeLabel, readInlineTarget, readLabel } from '../commonmark/link-syntax.ts'
@@ -25,6 +27,8 @@ export type LinkDefinitions = ReadonlyMap<string, LinkDefinition>
 
 type Bracket = { active: boolean; image: boolean; kind: 'open'; start: number }
 
+type HighlightDelimiter = { closes: boolean; holder: AdfNode; index: number; line: number; opens: boolean; position: number }
+
 type Pairing = EmphasisPairing<Run>
 
 type Piece =
@@ -33,6 +37,7 @@ type Piece =
   | { alt: string; kind: 'image'; node: AdfNode }
   | { kind: 'nodes'; nodes: AdfNode[] }
   | { canClose: boolean; canOpen: boolean; character: string; kind: 'run'; length: number }
+  | { closes: boolean; kind: 'highlight'; opens: boolean }
 
 type Run = { canClose: boolean; canOpen: boolean; character: string; index: number; length: number }
 
@@ -42,6 +47,7 @@ type Scan = {
   // Pieces below this have been walked for openers to deactivate: an image close folds the link-marked piece into alt text, leaving this the only record that the brackets around it are doomed.
   deactivatedBefore: number
   definitions: LinkDefinitions
+  highlights: boolean
   openingSpellableLink: boolean
   path: ConvertErrorPath
   pending: string
@@ -53,29 +59,21 @@ type Scan = {
 type SlotContent = { carry: boolean; nodes: AdfNode[] }
 
 const carriedInMark = 'no mark spelling wraps an opaque carry: the carried node restores exactly, marks included'
+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>'
 
-export function parseInlineContent(source: string, definitions: LinkDefinitions, path: ConvertErrorPath, container: LineContainer): Result<InlineContent> {
+export function parseInlineContent(source: string, definitions: LinkDefinitions, path: ConvertErrorPath, container: LineContainer, flavour: Flavour): Result<InlineContent> {
-  return parseInline(source, definitions, path, container, noSpans)
+  return parseInline(source, definitions, path, container, noSpans, flavour === 'plain')
 }
 
-function parseInline(source: string, definitions: LinkDefinitions, path: ConvertErrorPath, container: LineContainer | undefined, spans: NestedSpans): Result<InlineContent> {
+function parseInline(source: string, definitions: LinkDefinitions, path: ConvertErrorPath, container: LineContainer | undefined, spans: NestedSpans, highlights: boolean): Result<InlineContent> {
-  const scan: Scan = { container, deactivatedBefore: 0, definitions, openingSpellableLink: false, path, pending: '', pieces: [], source, spans }
+  const scan: Scan = { container, deactivatedBefore: 0, definitions, highlights, openingSpellableLink: false, path, pending: '', pieces: [], source, spans }
   let index = 0
   while (index < source.length) {
     switch (source.charAt(index)) {
-      case '\\':
-        index = readBackslash(scan, index)
-        break
-      case '\n':
-        index = readLineEnding(scan, index)
-        break
-      case '`':
-        index = readBackticks(scan, index)
-        break
       case '<': {
         const angle = readAngle(scan, index)
         if (!angle.ok) return angle
@@ -101,20 +99,34 @@ function parseInline(source: string, definitions: LinkDefinitions, path: Convert
         index = closed.value
         break
       }
-      case '*':
-      case '_':
-      case '~':
-        index = readDelimiterRun(scan, index)
-        break
       default:
-        scan.pending += source.charAt(index)
+        index = readCharacter(scan, index)
-        index += 1
     }
   }
   flush(scan, container !== undefined)
   return assemble(scan)
 }
 
+function readCharacter(scan: Scan, index: number): number {
+  switch (scan.source.charAt(index)) {
+    case '\\':
+      return readBackslash(scan, index)
+    case '\n':
+      return readLineEnding(scan, index)
+    case '`':
+      return readBackticks(scan, index)
+    case '*':
+    case '_':
+    case '~':
+      return readDelimiterRun(scan, index)
+    case '=':
+      return readEquals(scan, index)
+    default:
+      scan.pending += scan.source.charAt(index)
+      return index + 1
+  }
+}
+
 function readBackslash(scan: Scan, index: number): number {
   if (scan.source.charAt(index + 1) === '\n') {
     // CommonMark strips the spaces the two-space break is spelled with, and keeps those before a backslash.
@@ -230,7 +242,7 @@ 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)
+  const parsed = parseInline(span.content, scan.definitions, scan.path, undefined, span.spans, false)
   if (!parsed.ok) return parsed
   if (parsed.value.image !== undefined) return failure('unmappable-image', imageAlone, scan.path)
   return success(parsed.value)
@@ -250,7 +262,7 @@ function assemble(scan: Scan): Result<InlineContent> {
   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)
+  const nodes = resolveNodes(scan.pieces, scan.path, true)
   if (!nodes.ok) return nodes
   if (scan.openingSpellableLink) {
     const takesDirective = openingLinkTakesDirective(nodes.value, scan.path)
@@ -289,6 +301,24 @@ function readDelimiterRun(scan: Scan, index: number): number {
   return index + length
 }
 
+// A delimiter is bounded outside by the code point beyond it, and flanks by the character inside it.
+function readEquals(scan: Scan, index: number): number {
+  if (!scan.highlights || !scan.source.startsWith(highlightDelimiter, index)) {
+    scan.pending += '='
+    return index + 1
+  }
+  const end = index + highlightDelimiter.length
+  const before = Array.from(scan.source.slice(Math.max(0, index - 2), index)).at(-1) ?? ''
+  const after = Array.from(scan.source.slice(end, end + 2))[0] ?? ''
+  flush(scan, false)
+  scan.pieces.push({ closes: flanks(before) && !isWordCharacter(after), kind: 'highlight', opens: flanks(after) && !isWordCharacter(before) })
+  return end
+}
+
+function flanks(character: string): boolean {
+  return character !== '' && !/\s/.test(character)
+}
+
 function readAutolink(source: string, index: number): { length: number; node: AdfNode } | undefined {
   const bracketed = readBracketedAutolink(source, index)
   if (bracketed !== undefined) return { length: bracketed, node: linkedText(source.slice(index + 1, index + bracketed - 1), '') }
@@ -361,7 +391,7 @@ function closeLink(scan: Scan, at: number, inner: readonly Piece[], definition:
   }
   if (holdsImage(inner)) return failure('unmappable-image', imageAlone, scan.path)
   if (holdsCarry(inner)) return failure('unsupported-node-shape', carriedInMark, scan.path)
-  const resolved = resolveNodes(inner, scan.path)
+  const resolved = resolveNodes(inner, scan.path, 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.
@@ -399,7 +429,7 @@ function closeImage(scan: Scan, at: number, inner: readonly Piece[], definition:
 }
 
 function imageAlt(inner: readonly Piece[], path: ConvertErrorPath): Result<string> {
-  const nodes = resolveNodes(inner, path)
+  const nodes = resolveNodes(inner, path, false)
   if (!nodes.ok) return nodes
   return success(nodes.value.map(altText).join(''))
 }
@@ -412,20 +442,25 @@ function altText(node: AdfNode): string {
   return typeof spelled === 'string' ? spelled : (node.text ?? '')
 }
 
-function resolveNodes(pieces: readonly Piece[], path: ConvertErrorPath): Result<AdfNode[]> {
+// 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[]> {
   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)
+  markHighlights(pieces, nodes, highlights ? pairedHighlights(pieces, nodes) : [])
   return success(mergeAdjacentText(nodes.flat()))
 }
 
 // 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[] {
   switch (piece.kind) {
     case 'carry':
       return [piece.node]
+    case 'highlight':
+      return [{ text: '', type: 'text' }]
     case 'image':
       return piece.alt === '' ? [] : [{ text: piece.alt, type: 'text' }]
     case 'nodes':
@@ -472,6 +507,63 @@ function markPairings(pieces: readonly Piece[], nodes: AdfNode[][], pairings: re
   return true
 }
 
+function highlightDelimiters(pieces: readonly Piece[], nodes: readonly AdfNode[][]): HighlightDelimiter[] {
+  const found: HighlightDelimiter[] = []
+  let line = 0
+  let position = 0
+  for (const [index, piece] of pieces.entries()) {
+    const held = nodes[index] ?? []
+    const [holder] = held
+    if (piece.kind === 'highlight' && holder !== undefined) {
+      found.push({ closes: piece.closes, holder, index, line, opens: piece.opens, position })
+      position += highlightDelimiter.length
+      continue
+    }
+    for (const node of held) {
+      if (node.type === 'text') position += node.text?.length ?? 0
+      else line += 1
+    }
+  }
+  return found
+}
+
+// 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 }[] {
+  const found = highlightDelimiters(pieces, nodes)
+  const paired: { closer: number; opener: number }[] = []
+  let closer = 0
+  let resume = 0
+  for (const opener of found) {
+    if (!opener.opens || opener.position < resume) continue
+    const earliest = opener.position + highlightDelimiter.length + 1
+    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
+    paired.push({ closer: candidate.index, opener: opener.index })
+    resume = candidate.position + highlightDelimiter.length
+  }
+  return paired
+}
+
+// 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 {
+  for (const [index, piece] of pieces.entries()) {
+    if (piece.kind === 'highlight') nodes[index] = (nodes[index] ?? []).map((holder) => ({ ...holder, text: highlightDelimiter }))
+  }
+  for (const { closer, opener } of paired) {
+    nodes[opener] = []
+    nodes[closer] = []
+    for (let index = opener + 1; index < closer; index += 1) nodes[index] = (nodes[index] ?? []).map(highlighted)
+  }
+}
+
+function highlighted(node: AdfNode): AdfNode {
+  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] }
+}
+
 function markType(character: string, used: number): string {
   if (character === '~') return 'strike'
   return used === 2 ? 'strong' : 'em'

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

@@ -2,6 +2,7 @@ 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 { LineContainer } from '../line-container.ts'
 import type { LinkDefinitions } from './inline-content.ts'
 import { carryName, readCarriedBlock } from '../opaque-carry.ts'
@@ -10,22 +11,39 @@ import { failure, faulted, positioned, success, type ConvertErrorPath, type Pars
 import { languageSlot } from '../code-language.ts'
 import { largestNesting } from '../../nesting.ts'
 import { listBreakName, listBreakSpelling } from '../block-directive.ts'
-import { nodeAttrs } from '../../adf/document.ts'
+import { nodeAttrs, nodeContent } from '../../adf/document.ts'
 import { parseBlocks } from './blocks.ts'
 import { parseInlineContent } from './inline-content.ts'
+import { readAlertMarker, readTaskMarker } from '../plain-conventions.ts'
 import { readBlockDirectiveNode } from './directive-nodes.ts'
 import { unsupportedNodeShape } from '../directive-syntax.ts'
 
+type Paragraph = Extract<Block, { kind: 'paragraph' }>
+
+// `inExpand` is whether an expand holds the blocks, which makes a folded callout a nestedExpand.
+type Reading = { definitions: LinkDefinitions; flavour: Flavour; inExpand: boolean; memo: SpellingMemo }
+
 const documentStart: SourcePosition = { line: 1, offset: 0 }
+const imageAfterMarker = 'an image fits only as a paragraph of its own: this one continues the paragraph a marker opens, which a blank line before it ends'
+const imageOnMarkerLine = 'an image fits only as a paragraph of its own: this one shares a line with a marker'
 
 export function markdownToAdf(markdown: string): Result<AdfDocument, ParseError> {
+  return readDocument(markdown, 'lossless')
+}
+
+export function plainMarkdownToAdf(markdown: string): Result<AdfDocument, ParseError> {
+  return readDocument(markdown, 'plain')
+}
+
+function readDocument(markdown: string, flavour: Flavour): Result<AdfDocument, ParseError> {
   const parsed = parseBlocks(markdown)
-  const content = positioned(readBlocks(parsed.blocks, parsed.definitions, [], 0, new Map()), documentStart)
+  const reading: Reading = { definitions: parsed.definitions, flavour, inExpand: false, memo: new Map() }
+  const content = positioned(readBlocks(parsed.blocks, reading, [], 0), documentStart)
   if (!content.ok) return content
   return success(content.value.length === 0 ? { type: 'doc', version: 1 } : { content: content.value, type: 'doc', version: 1 })
 }
 
-function readBlocks(blocks: readonly Block[], definitions: LinkDefinitions, path: ConvertErrorPath, depth: number, memo: SpellingMemo): Result<AdfNode[]> {
+function readBlocks(blocks: readonly Block[], reading: Reading, path: ConvertErrorPath, depth: number): Result<AdfNode[]> {
   if (depth > largestNesting) return failure('unsupported-nesting-depth', `the input nests deeper than the ${largestNesting} levels the parser carries`, path)
   const content: AdfNode[] = []
   for (const [index, block] of blocks.entries()) {
@@ -35,7 +53,7 @@ function readBlocks(blocks: readonly Block[], definitions: LinkDefinitions, path
       if (fault !== undefined) return positioned(faulted(fault, nodePath), block.position)
       continue
     }
-    const node = positioned(readBlock(block, definitions, nodePath, depth, memo), block.position)
+    const node = positioned(readBlock(block, reading, nodePath, depth), block.position)
     if (!node.ok) return node
     content.push(node.value)
   }
@@ -55,50 +73,124 @@ function partsFault(): ConvertFault {
   return unsupportedNodeShape(`${listBreakName} parts two adjacent lists of one type: this one parts something else`)
 }
 
-function readBlock(block: Block, definitions: LinkDefinitions, path: ConvertErrorPath, depth: number, memo: SpellingMemo): Result<AdfNode> {
+function readBlock(block: Block, reading: Reading, path: ConvertErrorPath, depth: number): Result<AdfNode> {
   switch (block.kind) {
     case 'blockquote':
-      return containerNode({ type: 'blockquote' }, block.blocks, definitions, path, depth, memo)
+      return reading.flavour === 'plain' ? quoteNode(block.blocks, reading, path, depth) : containerNode({ type: 'blockquote' }, block.blocks, reading, path, depth)
     case 'bulletList':
-      return listNode({ type: 'bulletList' }, block.items, definitions, path, depth, memo)
+      return reading.flavour === 'plain' ? bulletNode(block.items, reading, path, depth) : listNode({ type: 'bulletList' }, block.items, reading, path, depth)
     case 'code':
       return codeBlockNode(block.language, block.text, path, depth)
     case 'directive':
-      return directiveNode(block, definitions, path, depth, memo)
+      return directiveNode(block, reading, path, depth)
     case 'fault':
       return faulted(block.fault, path)
     case 'heading':
-      return contentNode({ attrs: { level: block.level }, type: 'heading' }, block.text, definitions, path, 'heading')
+      return contentNode({ attrs: { level: block.level }, type: 'heading' }, block.text, reading, path, 'heading')
     case 'html':
       return failure('unmappable-html', `no raw HTML converts at this version: ${block.construct}`, path)
     case 'orderedList':
-      return listNode({ attrs: { order: block.start }, type: 'orderedList' }, block.items, definitions, path, depth, memo)
+      return listNode({ attrs: { order: block.start }, type: 'orderedList' }, block.items, reading, path, depth)
     case 'paragraph':
-      return paragraphNode(block.text, definitions, path)
+      return paragraphNode(block.text, reading, path)
     case 'rule':
       return success({ type: 'rule' })
     case 'table':
-      return tableNode(block.rows, definitions, path)
+      return tableNode(block.rows, reading, path)
   }
 }
 
-function directiveNode(block: DirectiveBlock, definitions: LinkDefinitions, path: ConvertErrorPath, depth: number, memo: SpellingMemo): Result<AdfNode> {
+function markerLed<T extends { length: number }>(block: Block | undefined, read: (text: string) => T | undefined): { marker: T; position: SourcePosition; text: string } | undefined {
+  if (block?.kind !== 'paragraph') return undefined
+  const marker = read(block.text)
+  if (marker === undefined) return undefined
+  const text = block.text.slice(marker.length)
+  return text === '' || /^(?:[ \t\n]|\\\n)/.test(text) ? { marker, position: block.position, text } : undefined
+}
+
+function markerLine(text: string): { line: string; rest: string } {
+  const lineEnd = text.indexOf('\n')
+  const line = lineEnd === -1 ? text : text.slice(0, lineEnd)
+  const hardBreak = lineEnd !== -1 && /(?:^|[^\\])(?:\\\\)*\\$/.test(line)
+  return { line: (hardBreak ? line.slice(0, -1) : line).replace(/^[ \t]+/, ''), rest: lineEnd === -1 ? '' : text.slice(lineEnd + 1) }
+}
+
+function paragraphsOf(position: SourcePosition, ...texts: string[]): Paragraph[] {
+  return texts.filter((text) => text !== '').map((text) => ({ kind: 'paragraph', position, text }))
+}
+
+function quoteNode(blocks: readonly Block[], reading: Reading, path: ConvertErrorPath, depth: number): Result<AdfNode> {
+  const [first, ...body] = blocks
+  const led = markerLed(first, readAlertMarker)
+  if (led === undefined) return containerNode({ type: 'blockquote' }, blocks, reading, path, depth)
+  const { folded, panelType } = led.marker
+  const { line, rest } = markerLine(led.text)
+  if (!folded) return filledNode({ attrs: { panelType }, type: 'panel' }, readMarked(paragraphsOf(led.position, line, rest), line !== '', body, reading, path, depth))
+  const title = parseInlineContent(line, reading.definitions, path, 'paragraph', 'lossless')
+  if (!title.ok) return title
+  if (title.value.image !== undefined) return failure('unmappable-image', imageOnMarkerLine, path)
+  const text = title.value.nodes.map((node) => node.text ?? '').join('')
+  const type = reading.inExpand ? 'nestedExpand' : 'expand'
+  return filledNode(text === '' ? { type } : { attrs: { title: text }, type }, readMarked(paragraphsOf(led.position, rest), false, body, { ...reading, inExpand: true }, path, depth))
+}
+
+// Atlassian's schema requires a panel and an expand to hold a block.
+function filledNode(node: AdfNode, content: Result<AdfNode[]>): Result<AdfNode> {
+  if (!content.ok) return content
+  return success({ ...node, content: content.value.length === 0 ? [{ type: 'paragraph' }] : content.value })
+}
+
+// A paragraph split off a marker still refuses the image it held beside it; `onMarkerLine` is whether the first one opens on the marker's line.
+function readMarked(marked: readonly Paragraph[], onMarkerLine: boolean, others: readonly Block[], reading: Reading, path: ConvertErrorPath, depth: number): Result<AdfNode[]> {
+  const read = readBlocks([...marked, ...others], reading, path, depth + 1)
+  if (!read.ok) return read
+  const image = read.value.slice(0, marked.length).findIndex((node) => node.type === 'mediaSingle')
+  if (image === -1) return read
+  return failure('unmappable-image', image === 0 && onMarkerLine ? imageOnMarkerLine : imageAfterMarker, [...path, 'content', image])
+}
+
+// A task list trailing an item's blocks stands beside it, as ADF nests one.
+function bulletNode(items: readonly Block[][], reading: Reading, path: ConvertErrorPath, depth: number): Result<AdfNode> {
+  const led = []
+  for (const [first, ...others] of items) {
+    const marked = markerLed(first, readTaskMarker)
+    if (marked === undefined) return listNode({ type: 'bulletList' }, items, reading, path, depth)
+    led.push({ ...marked, others })
+  }
+  const tasks: AdfNode[] = []
+  for (const [index, { marker, others, position, text }] of led.entries()) {
+    const read = readMarked(paragraphsOf(position, text.replace(/^(?:[ \t\n]|\\\n)+/, '')), markerLine(text).line !== '', others, reading, [...path, 'content', index], depth)
+    if (!read.ok) return read
+    let beside = read.value.length
+    while (read.value[beside - 1]?.type === 'taskList') beside -= 1
+    const kept = read.value.slice(0, beside)
+    const [only] = kept
+    const attrs = { state: marker.state }
+    const inline = kept.length <= 1 && (only === undefined || only.type === 'paragraph')
+    tasks.push(inline ? { attrs, content: nodeContent(only ?? {}).slice(), type: 'taskItem' } : { attrs, content: kept, type: 'blockTaskItem' })
+    for (const nested of read.value.slice(beside)) tasks.push(nested)
+  }
+  return success({ content: tasks, type: 'taskList' })
+}
+
+function directiveNode(block: DirectiveBlock, reading: Reading, path: ConvertErrorPath, depth: number): Result<AdfNode> {
   const read = readBlockDirectiveNode(block.name, block.argument, block.attributes, path)
   if (!read.ok) return read
-  const built = directiveBody(read.value, block.blocks, definitions, path, depth, memo)
+  const inExpand = reading.inExpand || read.value.node.type === 'expand' || read.value.node.type === 'nestedExpand'
+  const built = directiveBody(read.value, block.blocks, { ...reading, inExpand }, path, depth)
   if (!built.ok) return built
-  const readable = commonMarkSpelling(built.value, path, depth, memo)
+  const readable = commonMarkSpelling(built.value, path, depth, reading.memo)
   if (readable === undefined) return built
   if (!readable.ok) return readable
   return failure('unsupported-node-shape', `${built.value.type} takes the CommonMark spelling, not the directive form`, path)
 }
 
-function directiveBody(read: BlockDirectiveNode, blocks: Block[] | undefined, definitions: LinkDefinitions, path: ConvertErrorPath, depth: number, memo: SpellingMemo): Result<AdfNode> {
+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)
   if (contentModel === 'code') return codeDirectiveNode(node, blocks, path)
-  if (contentModel === 'inline') return inlineBodyNode(node, blocks, definitions, path)
+  if (contentModel === 'inline') return inlineBodyNode(node, blocks, reading, path)
-  return containerNode(node, blocks, definitions, path, depth, memo)
+  return containerNode(node, blocks, reading, path, depth)
 }
 
 function codeDirectiveNode(node: AdfNode, blocks: readonly Block[], path: ConvertErrorPath): Result<AdfNode> {
@@ -114,13 +206,13 @@ function codeDirectiveNode(node: AdfNode, blocks: readonly Block[], path: Conver
   return success(withContent(spelled, only.text === '' ? [] : [{ text: only.text, type: 'text' }]))
 }
 
-function tableNode(rows: readonly string[][], definitions: LinkDefinitions, path: ConvertErrorPath): Result<AdfNode> {
+function tableNode(rows: readonly string[][], reading: Reading, path: ConvertErrorPath): Result<AdfNode> {
   const content: AdfNode[] = []
   for (const [rowIndex, cells] of rows.entries()) {
     const type = rowIndex === 0 ? 'tableHeader' : 'tableCell'
     const row: AdfNode[] = []
     for (const [cellIndex, cell] of cells.entries()) {
-      const paragraph = contentNode({ type: 'paragraph' }, cell, definitions, [...path, 'content', rowIndex, 'content', cellIndex, 'content', 0], 'table-cell')
+      const paragraph = contentNode({ type: 'paragraph' }, cell, reading, [...path, 'content', rowIndex, 'content', cellIndex, 'content', 0], 'table-cell')
       if (!paragraph.ok) return paragraph
       row.push({ content: [paragraph.value], type })
     }
@@ -129,16 +221,16 @@ function tableNode(rows: readonly string[][], definitions: LinkDefinitions, path
   return success({ content, type: 'table' })
 }
 
-function inlineBodyNode(node: AdfNode, blocks: readonly Block[], definitions: LinkDefinitions, path: ConvertErrorPath): Result<AdfNode> {
+function inlineBodyNode(node: AdfNode, blocks: readonly Block[], reading: Reading, path: ConvertErrorPath): Result<AdfNode> {
   if (blocks.length === 0) return success(node)
   const only = blocks.length === 1 ? blocks[0] : undefined
   if (only?.kind === 'fault') return positioned(faulted(only.fault, path), only.position)
   if (only?.kind !== 'paragraph') return failure('unsupported-node-shape', `${node.type} takes one paragraph as its body: this body is not one`, path)
-  return positioned(contentNode(node, only.text, definitions, path, 'paragraph'), only.position)
+  return positioned(contentNode(node, only.text, reading, path, 'paragraph'), only.position)
 }
 
-function containerNode(node: AdfNode, blocks: readonly Block[], definitions: LinkDefinitions, path: ConvertErrorPath, depth: number, memo: SpellingMemo): Result<AdfNode> {
+function containerNode(node: AdfNode, blocks: readonly Block[], reading: Reading, path: ConvertErrorPath, depth: number): Result<AdfNode> {
-  const content = readBlocks(blocks, definitions, path, depth + 1, memo)
+  const content = readBlocks(blocks, reading, path, depth + 1)
   if (!content.ok) return content
   return success(withContent(node, content.value))
 }
@@ -147,10 +239,10 @@ function withContent(node: AdfNode, content: readonly AdfNode[]): AdfNode {
   return content.length === 0 ? node : { ...node, content: [...content] }
 }
 
-function listNode(node: AdfNode, items: readonly Block[][], definitions: LinkDefinitions, path: ConvertErrorPath, depth: number, memo: SpellingMemo): Result<AdfNode> {
+function listNode(node: AdfNode, items: readonly Block[][], reading: Reading, path: ConvertErrorPath, depth: number): Result<AdfNode> {
   const content: AdfNode[] = []
   for (const [index, blocks] of items.entries()) {
-    const item = containerNode({ type: 'listItem' }, blocks, definitions, [...path, 'content', index], depth, memo)
+    const item = containerNode({ type: 'listItem' }, blocks, reading, [...path, 'content', index], depth)
     if (!item.ok) return item
     content.push(item.value)
   }
@@ -168,15 +260,15 @@ function codeBlockNode(language: string, text: string, path: ConvertErrorPath, d
 }
 
 // spec/flavour.md, The CommonMark image: only a plain paragraph gives an image the block it needs.
-function paragraphNode(text: string, definitions: LinkDefinitions, path: ConvertErrorPath): Result<AdfNode> {
+function paragraphNode(text: string, reading: Reading, path: ConvertErrorPath): Result<AdfNode> {
-  const content = parseInlineContent(text, definitions, path, 'paragraph')
+  const content = parseInlineContent(text, reading.definitions, path, 'paragraph', reading.flavour)
   if (!content.ok) return content
   const image = content.value.image
   return success(image === undefined ? withContent({ type: 'paragraph' }, content.value.nodes) : image)
 }
 
-function contentNode(node: AdfNode, text: string, definitions: LinkDefinitions, path: ConvertErrorPath, container: LineContainer): Result<AdfNode> {
+function contentNode(node: AdfNode, text: string, reading: Reading, path: ConvertErrorPath, container: LineContainer): Result<AdfNode> {
-  const content = parseInlineContent(text, definitions, path, container)
+  const content = parseInlineContent(text, reading.definitions, path, container, reading.flavour)
   if (!content.ok) return content
   if (content.value.image !== undefined) return failure('unmappable-image', `no ADF node carries an image inside a ${node.type}`, path)
   return success(withContent(node, content.value.nodes))

src/markdown/parse/plain-lift.test.ts

@@ -1,201 +0,0 @@
-import assert from 'node:assert/strict'
-import test from 'node:test'
-
-import type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from '../../adf/document.ts'
-import { adfToMarkdown } from '../emit/adf-to-markdown.ts'
-import { largestNesting } from '../../nesting.ts'
-import { liftFromPlain } from './plain-lift.ts'
-import { markdownToAdf } from './markdown-to-adf.ts'
-import { reduceToPlain } from '../emit/plain-reduction.ts'
-import { toEditorNormal } from '../../adf/editor-normal.ts'
-
-const code: AdfMark = { type: 'code' }
-const em: AdfMark = { type: 'em' }
-const highlight: AdfMark = { attrs: { color: '#f8e6a0' }, type: 'backgroundColor' }
-const strong: AdfMark = { type: 'strong' }
-
-function lifted(markdown: string): readonly AdfNode[] | string {
-  const parsed = markdownToAdf(markdown)
-  return parsed.ok ? (toEditorNormal(liftFromPlain(parsed.value)).content ?? []) : parsed.error.code
-}
-
-function normal(...blocks: AdfNode[]): readonly AdfNode[] {
-  return toEditorNormal(document(...blocks)).content ?? []
-}
-
-function document(...content: AdfNode[]): AdfDocument {
-  return { content, type: 'doc', version: 1 }
-}
-
-// ADF the reduction wrote, spelled and read back through the lift.
-function roundTripped(...content: AdfNode[]): readonly AdfNode[] | string {
-  const reduced = reduceToPlain(document(...content))
-  const markdown = reduced.ok ? adfToMarkdown(reduced.value) : reduced
-  return markdown.ok ? lifted(markdown.value) : markdown.error.code
-}
-
-function text(value: string, ...marks: AdfMark[]): AdfNode {
-  return marks.length === 0 ? { text: value, type: 'text' } : { marks, text: value, type: 'text' }
-}
-
-function node(type: string, attrs: AdfAttributes, ...content: AdfNode[]): AdfNode {
-  return { attrs, content, type }
-}
-
-function bare(type: string, ...content: AdfNode[]): AdfNode {
-  return { content, type }
-}
-
-function paragraph(...content: AdfNode[]): AdfNode {
-  return bare('paragraph', ...content)
-}
-
-function said(value: string): AdfNode {
-  return paragraph(text(value))
-}
-
-function panel(panelType: string, ...content: AdfNode[]): AdfNode {
-  return node('panel', { panelType }, ...content)
-}
-
-function task(state: string, ...content: AdfNode[]): AdfNode {
-  return node('taskItem', { state }, ...content)
-}
-
-test('lifts an alert to a panel by its GitHub word, in any case', () => {
-  const alert = (word: string): readonly AdfNode[] | string => lifted(`> [!${word}]\n>\n> Check it.\n`)
-  assert.deepEqual(alert('NOTE'), [panel('info', said('Check it.'))])
-  assert.deepEqual(alert('IMPORTANT'), [panel('note', said('Check it.'))])
-  assert.deepEqual(alert('TIP'), [panel('tip', said('Check it.'))])
-  assert.deepEqual(alert('WARNING'), [panel('warning', said('Check it.'))])
-  assert.deepEqual(alert('CAUTION'), [panel('error', said('Check it.'))])
-  assert.deepEqual(alert('Warning'), [panel('warning', said('Check it.'))])
-  assert.deepEqual(alert('caution'), [panel('error', said('Check it.'))])
-})
-
-test('lifts an Obsidian callout to a panel by what its word means, any other word info', () => {
-  const alert = (word: string): unknown => {
-    const blocks = lifted(`> [!${word}]\n> Body.\n`)
-    return typeof blocks === 'string' ? blocks : blocks[0]?.attrs
-  }
-  assert.deepEqual(alert('hint'), { panelType: 'tip' })
-  for (const word of ['success', 'check', 'Done']) assert.deepEqual(alert(word), { panelType: 'success' }, word)
-  assert.deepEqual(alert('attention'), { panelType: 'warning' })
-  for (const word of ['danger', 'error', 'failure', 'fail', 'missing', 'BUG']) assert.deepEqual(alert(word), { panelType: 'error' }, word)
-  for (const word of ['info', 'note', 'question', 'my-type']) assert.deepEqual(alert(word), { panelType: 'info' }, word)
-})
-
-test('reads text after an alert marker in its paragraph as the panel first body paragraph', () => {
-  assert.deepEqual(lifted('> [!NOTE]\n> Line **one**.\n>\n> Two.\n'), [panel('info', paragraph(text('Line '), text('one', strong), text('.')), said('Two.'))])
-  assert.deepEqual(lifted('> [!tip] Title\n'), [panel('tip', said('Title'))])
-  assert.deepEqual(lifted('> [!NOTE]\\\n> Broken.\n'), [panel('info', said('Broken.'))])
-  assert.deepEqual(lifted('> [!NOTE]\n'), normal(panel('info', paragraph())))
-  assert.deepEqual(lifted('> > [!WARNING]\n> > Inner.\n'), [bare('blockquote', panel('warning', said('Inner.')))])
-})
-
-test('leaves a quote plain where its first line is no alert marker', () => {
-  for (const markdown of ['> [!NOTE]x\n', '> **[!NOTE]**\n', '> See [!NOTE]\n', '> [!NOTE]**x**\n', '> [!]\n', '> ```\n> [!NOTE]\n> ```\n']) {
-    const blocks = lifted(markdown)
-    assert.equal(typeof blocks !== 'string' && blocks[0]?.type, 'blockquote', markdown)
-  }
-})
-
-test('lifts a folded callout to an expand titled by the rest of its marker paragraph, whatever the word', () => {
-  assert.deepEqual(lifted('> [!NOTE]- Build log\n>\n> Line.\n'), [node('expand', { title: 'Build log' }, said('Line.'))])
-  assert.deepEqual(lifted('> [!bug]+ Open **by** default\n> still title\n>\n> Line.\n'), [node('expand', { title: 'Open by default still title' }, said('Line.'))])
-  assert.deepEqual(lifted('> [!NOTE]- Two\\\n> lines\n'), normal(node('expand', { title: 'Two\nlines' }, paragraph())))
-  assert.deepEqual(lifted('> [!NOTE]-\n>\n> Line.\n'), [bare('expand', said('Line.'))])
-})
-
-test('lifts 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(lifted(markdown), normal(node('expand', { title: 'Outer' }, node('nestedExpand', { title: 'Inner' }, said('Deep.')), panel('tip', bare('nestedExpand', paragraph())))))
-  assert.deepEqual(lifted('- > [!NOTE]-\n'), normal(bare('bulletList', bare('listItem', bare('expand', paragraph())))))
-})
-
-test('lifts a bullet list whose every item leads with a task marker to a task list', () => {
-  assert.deepEqual(lifted('- [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(lifted('- [x]\n- [ ]\\\n  after\n'), normal(bare('taskList', task('DONE'), task('TODO', text('after')))))
-})
-
-test('moves a nested task list beside its item and makes an item holding more than one block a block task item', () => {
-  assert.deepEqual(lifted('- [x] Parent\n  - [ ] Child\n- [ ] Next\n'), [bare('taskList', task('DONE', text('Parent')), bare('taskList', task('TODO', text('Child'))), task('TODO', text('Next')))])
-  assert.deepEqual(lifted('- [x] First.\n\n  Second.\n- [ ]\n\n  ```\n  x\n  ```\n'), [
-    bare('taskList', node('blockTaskItem', { state: 'DONE' }, said('First.'), said('Second.')), node('blockTaskItem', { state: 'TODO' }, bare('codeBlock', text('x')))),
-  ])
-  assert.deepEqual(lifted('- [x] A\n  - plain\n'), [bare('taskList', node('blockTaskItem', { state: 'DONE' }, said('A'), bare('bulletList', bare('listItem', said('plain')))))])
-})
-
-test('leaves mixed, ordered and unmarked lists plain', () => {
-  for (const markdown of ['- [x] a\n- b\n', '1. [x] a\n', '- [x]a\n', '- **[x]** a\n', '- [x]**a**\n', '- [-] a\n', '- > [x] a\n']) {
-    const blocks = lifted(markdown)
-    assert.notEqual(typeof blocks !== 'string' && blocks[0]?.type, 'taskList', markdown)
-    assert.equal(JSON.stringify(blocks).includes('taskItem'), false, markdown)
-  }
-  assert.deepEqual(lifted('- plain\n  - [ ] nested\n'), [bare('bulletList', bare('listItem', said('plain'), bare('taskList', task('TODO', text('nested')))))])
-})
-
-test('lifts a == pair to the editor default highlight, Yellow200 #f8e6a0 in @atlaskit/adf-schema 57.6.8', () => {
-  assert.deepEqual(lifted('a ==hi there== b\n'), [paragraph(text('a '), text('hi there', highlight), text(' b'))])
-  assert.deepEqual(lifted('**==hi==** b\n'), [paragraph(text('hi', highlight, strong), text(' b'))])
-  assert.deepEqual(lifted('==**a**_b_ `c`==\n'), [paragraph(text('a', highlight, strong), text('b', highlight, em), text(' ', highlight), text('c', code))])
-  assert.deepEqual(lifted('==`a`==\n'), [paragraph(text('a', code))])
-  assert.deepEqual(lifted('x==y==z ==a == b==, (==c==) _d_==e==\n'), [paragraph(text('x==y==z '), text('a == b', highlight), text(', ('), text('c', highlight), text(') '), text('d', em), text('e', highlight))])
-  assert.deepEqual(lifted('😀==b== ==c==😀 é==d==\n'), [paragraph(text('😀'), text('b', highlight), text(' '), text('c', highlight), text('😀 é==d=='))])
-  assert.deepEqual(lifted('# ==h==\n\n| ==c== |\n| --- |\n'), [
-    node('heading', { level: 1 }, text('h', highlight)),
-    bare('table', bare('tableRow', bare('tableHeader', paragraph(text('c', highlight))))),
-  ])
-  assert.deepEqual(lifted('> [!NOTE]\n> ==x==\n'), [panel('info', paragraph(text('x', highlight)))])
-  assert.deepEqual(lifted('==a==\\\n==b==\n'), [paragraph(text('a', highlight), { type: 'hardBreak' }, text('b', highlight))])
-})
-
-test('leaves a == no pair flanks as text', () => {
-  for (const markdown of ['a == b == c\n', 'if a==b and c==d then\n', 'a==b== c\n', '==a==b\n', '====\n', '`==x==`\n', '==a\\\nb==\n', '**==a**==\n', '==a', '== a==\n', '==a ==\n']) {
-    assert.equal(JSON.stringify(lifted(markdown)).includes('backgroundColor'), false, markdown)
-  }
-})
-
-test('lifts what the reduction wrote back to the node it reduced, less the attributes it drops', () => {
-  const localId = '01a0d99b-1f59-7e2c-a3d4-62c1f0b8e7a1'
-  for (const panelType of ['info', 'note', 'tip', 'warning', 'error']) {
-    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(expand), [node('expand', { title: 'Log' }, said('Line.'), node('nestedExpand', { title: 'Inner' }, said('Deep.')))])
-  const tasks = bare(
-    'taskList',
-    node('taskItem', { localId, state: 'DONE' }, text('Write')),
-    bare('taskList', task('TODO', text('Review'))),
-    node('blockTaskItem', { state: 'TODO' }, said('First.'), said('Second.')),
-    node('blockTaskItem', { state: 'DONE' }, bare('codeBlock', text('x'))),
-  )
-  const plainTasks = bare(
-    'taskList',
-    task('DONE', text('Write')),
-    bare('taskList', task('TODO', text('Review'))),
-    node('blockTaskItem', { state: 'TODO' }, said('First.'), said('Second.')),
-    node('blockTaskItem', { state: 'DONE' }, bare('codeBlock', text('x'))),
-  )
-  assert.deepEqual(roundTripped(tasks), [plainTasks])
-  const colour: AdfMark = { attrs: { color: '#c6edfb' }, type: 'backgroundColor' }
-  assert.deepEqual(roundTripped(paragraph(text('a '), text('hi', colour, strong), text(' b'))), [paragraph(text('a '), text('hi', highlight, strong), text(' b'))])
-})
-
-test('keeps what markdownToAdf reads that no row lifts, and refuses only what it refuses', () => {
-  assert.deepEqual(lifted('!adf:panel warning\n- [x] a\n!adf:/panel\n'), [panel('warning', bare('taskList', task('DONE', text('a'))))])
-  const future = bare('futureBlock', text('==x=='))
-  const carried = adfToMarkdown(document(future))
-  assert.deepEqual(carried.ok ? lifted(carried.value) : carried.error.code, [future])
-  const red: AdfMark = { attrs: { color: '#ff0000' }, type: 'backgroundColor' }
-  const held = paragraph(text('a ==b== c', red), text(' ==d '), { attrs: { note: 'x' }, text: 'e==f', type: 'text' }, text(' g=='))
-  const spelled = adfToMarkdown(document(held))
-  assert.deepEqual(spelled.ok ? lifted(spelled.value) : spelled.error.code, [paragraph(text('a ==b== c', red), text(' '), text('d ', highlight), { attrs: { note: 'x' }, text: 'e==f', type: 'text' }, text(' g', highlight))])
-  assert.equal(lifted('!adf:panel\n'), 'malformed-directive')
-  let deep = 'x\n'
-  for (let level = 0; level < largestNesting; level += 1) deep = `> ${deep}`
-  assert.equal(typeof lifted(deep), 'object')
-})

src/markdown/parse/plain-lift.ts

@@ -1,182 +0,0 @@
-import type { AdfDocument, AdfMark, AdfNode } from '../../adf/document.ts'
-import { blockNodeModel } from '../../adf/block-nodes.ts'
-import { isWordCharacter } from '../commonmark/emphasis-matching.ts'
-import { highlightDelimiter, readAlertMarker, readTaskMarker } from '../plain-conventions.ts'
-import { markdownToAdf } from './markdown-to-adf.ts'
-import { mergeAdjacentText, sameMarks } from '../../adf/editor-normal.ts'
-import { nodeAttrs, nodeContent, nodeMarks } from '../../adf/document.ts'
-import { success, type ParseError, type Result } from '../../result.ts'
-
-type Delimiter = { closes: boolean; holder: AdfNode; line: number; node: number; offset: number; opens: boolean; position: number }
-
-type MarkerLed<T> = { marker: T; rest: AdfNode[] }
-
-const editorHighlight: AdfMark = { attrs: { color: '#f8e6a0' }, type: 'backgroundColor' }
-
-export function plainMarkdownToAdf(markdown: string): Result<AdfDocument, ParseError> {
-  const parsed = markdownToAdf(markdown)
-  return parsed.ok ? success(liftFromPlain(parsed.value)) : parsed
-}
-
-export function liftFromPlain(document: AdfDocument): AdfDocument {
-  return { ...document, content: liftBlocks(nodeContent(document), false) }
-}
-
-function liftBlocks(blocks: readonly AdfNode[], inExpand: boolean): AdfNode[] {
-  return blocks.map((block) => liftBlock(block, inExpand))
-}
-
-function liftBlock(block: AdfNode, inExpand: boolean): AdfNode {
-  const model = blockNodeModel(block.type)?.contentModel
-  if (model === 'inline') return { ...block, content: highlighted(nodeContent(block)) }
-  if (model !== 'block') return block
-  if (block.type === 'blockquote') return liftQuote(block, inExpand)
-  const tasks = block.type === 'bulletList' ? taskItems(nodeContent(block), inExpand) : undefined
-  if (tasks !== undefined) return { content: tasks, type: 'taskList' }
-  return { ...block, content: liftBlocks(nodeContent(block), inExpand || block.type === 'expand' || block.type === 'nestedExpand') }
-}
-
-function paragraphOf(content: readonly AdfNode[]): AdfNode[] {
-  return content.length === 0 ? [] : [{ content: [...content], type: 'paragraph' }]
-}
-
-// The marker opens the block's unmarked text and whitespace or the line's end follows it.
-function markerLed<T extends { length: number }>(block: AdfNode | undefined, read: (text: string) => T | undefined): MarkerLed<T> | undefined {
-  if (block?.type !== 'paragraph') return undefined
-  const [first, ...others] = nodeContent(block)
-  if (first?.type !== 'text' || first.text === undefined || nodeMarks(first).length > 0) return undefined
-  const marker = read(first.text)
-  if (marker === undefined) return undefined
-  const tail = first.text.slice(marker.length)
-  const lineEnds = tail === '' && (others[0] === undefined || others[0].type === 'hardBreak')
-  if (!lineEnds && !/^[ \t]/.test(tail)) return undefined
-  const trimmed = tail.replace(/^[ \t]+/, '')
-  const rest = trimmed === '' ? others : [{ text: trimmed, type: 'text' }, ...others]
-  let from = 0
-  while (rest[from]?.type === 'hardBreak') from += 1
-  return { marker, rest: rest.slice(from) }
-}
-
-function liftQuote(quote: AdfNode, inExpand: boolean): AdfNode {
-  const [first, ...body] = nodeContent(quote)
-  const led = markerLed(first, readAlertMarker)
-  if (led === undefined) return { ...quote, content: liftBlocks(nodeContent(quote), inExpand) }
-  if (!led.marker.folded) return { attrs: { panelType: led.marker.panelType }, content: filled(liftBlocks([...paragraphOf(led.rest), ...body], inExpand)), type: 'panel' }
-  const title = led.rest.map((node) => node.text ?? (node.type === 'hardBreak' ? '\n' : '')).join('')
-  const content = filled(liftBlocks(body, true))
-  const type = inExpand ? 'nestedExpand' : 'expand'
-  return title === '' ? { content, type } : { attrs: { title }, content, type }
-}
-
-// Atlassian's schema requires a panel and an expand to hold a block.
-function filled(blocks: AdfNode[]): AdfNode[] {
-  return blocks.length === 0 ? [{ type: 'paragraph' }] : blocks
-}
-
-// A task list trailing an item's blocks stands beside it, as ADF nests one.
-function taskItems(items: readonly AdfNode[], inExpand: boolean): AdfNode[] | undefined {
-  if (items.length === 0) return undefined
-  const tasks: AdfNode[] = []
-  for (const item of items) {
-    const led = item.type === 'listItem' ? markerLed(nodeContent(item)[0], readTaskMarker) : undefined
-    if (led === undefined) return undefined
-    const blocks = liftBlocks([...paragraphOf(led.rest), ...nodeContent(item).slice(1)], inExpand)
-    let beside = blocks.length
-    while (blocks[beside - 1]?.type === 'taskList') beside -= 1
-    const kept = blocks.slice(0, beside)
-    const [only] = kept
-    const attrs = { state: led.marker.state }
-    const inline = kept.length <= 1 && (only === undefined || only.type === 'paragraph')
-    tasks.push(inline ? { attrs, content: [...nodeContent(only ?? {})], type: 'taskItem' } : { attrs, content: kept, type: 'blockTaskItem' })
-    for (const nested of blocks.slice(beside)) tasks.push(nested)
-  }
-  return tasks
-}
-
-function highlighted(inline: readonly AdfNode[]): AdfNode[] {
-  const pairs = pairedDelimiters(inline)
-  return pairs.length === 0 ? [...inline] : mergeAdjacentText(split(inline, pairs))
-}
-
-function textOf(node: AdfNode | undefined): string | undefined {
-  return node?.type === 'text' ? node.text : undefined
-}
-
-// Atlassian's schema refuses a highlight on code, a node holds one highlight, and a rebuilt node would lose its attributes.
-function heldWhole(node: AdfNode): boolean {
-  return Object.keys(nodeAttrs(node)).length > 0 || nodeMarks(node).some((mark) => mark.type === 'code' || mark.type === 'backgroundColor')
-}
-
-function delimiters(inline: readonly AdfNode[]): Delimiter[] {
-  const found: Delimiter[] = []
-  let line = 0
-  let position = 0
-  for (const [index, node] of inline.entries()) {
-    const text = textOf(node)
-    if (text === undefined) line += 1
-    if (text === undefined || heldWhole(node)) {
-      position += text?.length ?? 0
-      continue
-    }
-    for (let offset = text.indexOf(highlightDelimiter); offset !== -1; offset = text.indexOf(highlightDelimiter, offset + highlightDelimiter.length)) {
-      const end = offset + highlightDelimiter.length
-      const before = offset > 0 ? text[offset - 1] : textOf(inline[index - 1])?.at(-1)
-      const after = text[end] ?? textOf(inline[index + 1])?.[0]
-      // Outside a delimiter a node's edge bounds it, standing where the source spelled a mark's punctuation.
-      const outsideBefore = Array.from(text.slice(Math.max(0, offset - 2), offset)).at(-1) ?? ''
-      const outsideAfter = Array.from(text.slice(end, end + 2))[0] ?? ''
-      const closes = flanks(before) && !isWordCharacter(outsideAfter)
-      found.push({ closes, holder: node, line, node: index, offset, opens: flanks(after) && !isWordCharacter(outsideBefore), position: position + offset })
-    }
-    position += text.length
-  }
-  return found
-}
-
-function flanks(character: string | undefined): boolean {
-  return character !== undefined && !/\s/.test(character)
-}
-
-// Each opener takes the next closer holding at least one character after it, both in one line and under the same marks.
-function pairedDelimiters(inline: readonly AdfNode[]): Delimiter[] {
-  const found = delimiters(inline)
-  const paired: Delimiter[] = []
-  let closer = 0
-  let resume = 0
-  for (const opener of found) {
-    if (!opener.opens || opener.position < resume) continue
-    const earliest = opener.position + highlightDelimiter.length + 1
-    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
-    paired.push(opener, candidate)
-    resume = candidate.position + highlightDelimiter.length
-  }
-  return paired
-}
-
-function split(inline: readonly AdfNode[], paired: readonly Delimiter[]): AdfNode[] {
-  const lifted: AdfNode[] = []
-  let next = 0
-  for (const [index, node] of inline.entries()) {
-    const text = textOf(node)
-    if (text === undefined || heldWhole(node)) {
-      lifted.push(node)
-      continue
-    }
-    let from = 0
-    for (let delimiter = paired[next]; delimiter?.node === index; delimiter = paired[next]) {
-      pushPiece(lifted, node, text.slice(from, delimiter.offset), next % 2 === 1)
-      from = delimiter.offset + highlightDelimiter.length
-      next += 1
-    }
-    pushPiece(lifted, node, text.slice(from), next % 2 === 1)
-  }
-  return lifted
-}
-
-function pushPiece(lifted: AdfNode[], node: AdfNode, text: string, inPair: boolean): void {
-  const marks = inPair ? [editorHighlight, ...nodeMarks(node)] : [...nodeMarks(node)]
-  if (text !== '') lifted.push(marks.length === 0 ? { text, type: 'text' } : { marks, text, type: 'text' })
-}

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

@@ -0,0 +1,220 @@
+import assert from 'node:assert/strict'
+import test from 'node:test'
+
+import type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from '../../adf/document.ts'
+import { adfToMarkdown } from '../emit/adf-to-markdown.ts'
+import { largestNesting } from '../../nesting.ts'
+import { markdownToAdf, plainMarkdownToAdf } from './markdown-to-adf.ts'
+import { reduceToPlain } from '../emit/plain-reduction.ts'
+import { toEditorNormal } from '../../adf/editor-normal.ts'
+
+const code: AdfMark = { type: 'code' }
+const em: AdfMark = { type: 'em' }
+const highlight: AdfMark = { attrs: { color: '#f8e6a0' }, type: 'backgroundColor' }
+const strong: AdfMark = { type: 'strong' }
+
+function read(markdown: string): readonly AdfNode[] | string {
+  const parsed = plainMarkdownToAdf(markdown)
+  return parsed.ok ? (toEditorNormal(parsed.value).content ?? []) : parsed.error.code
+}
+
+function normal(...blocks: AdfNode[]): readonly AdfNode[] {
+  return toEditorNormal(document(...blocks)).content ?? []
+}
+
+function document(...content: AdfNode[]): AdfDocument {
+  return { content, type: 'doc', version: 1 }
+}
+
+// ADF the reduction wrote, spelled and read back.
+function roundTripped(...content: AdfNode[]): readonly AdfNode[] | string {
+  const reduced = reduceToPlain(document(...content))
+  const markdown = reduced.ok ? adfToMarkdown(reduced.value) : reduced
+  return markdown.ok ? read(markdown.value) : markdown.error.code
+}
+
+function text(value: string, ...marks: AdfMark[]): AdfNode {
+  return marks.length === 0 ? { text: value, type: 'text' } : { marks, text: value, type: 'text' }
+}
+
+function node(type: string, attrs: AdfAttributes, ...content: AdfNode[]): AdfNode {
+  return { attrs, content, type }
+}
+
+function bare(type: string, ...content: AdfNode[]): AdfNode {
+  return { content, type }
+}
+
+function paragraph(...content: AdfNode[]): AdfNode {
+  return bare('paragraph', ...content)
+}
+
+function said(value: string): AdfNode {
+  return paragraph(text(value))
+}
+
+function panel(panelType: string, ...content: AdfNode[]): AdfNode {
+  return node('panel', { panelType }, ...content)
+}
+
+function task(state: string, ...content: AdfNode[]): AdfNode {
+  return node('taskItem', { state }, ...content)
+}
+
+test('reads an alert to a panel by its GitHub word, in any case', () => {
+  const alert = (word: string): readonly AdfNode[] | string => read(`> [!${word}]\n>\n> Check it.\n`)
+  assert.deepEqual(alert('NOTE'), [panel('info', said('Check it.'))])
+  assert.deepEqual(alert('IMPORTANT'), [panel('note', said('Check it.'))])
+  assert.deepEqual(alert('TIP'), [panel('tip', said('Check it.'))])
+  assert.deepEqual(alert('WARNING'), [panel('warning', said('Check it.'))])
+  assert.deepEqual(alert('CAUTION'), [panel('error', said('Check it.'))])
+  assert.deepEqual(alert('Warning'), [panel('warning', said('Check it.'))])
+  assert.deepEqual(alert('caution'), [panel('error', said('Check it.'))])
+})
+
+test('reads an Obsidian callout to a panel by what its word means, any other word info', () => {
+  const alert = (word: string): unknown => {
+    const blocks = read(`> [!${word}]\n> Body.\n`)
+    return typeof blocks === 'string' ? blocks : blocks[0]?.attrs
+  }
+  assert.deepEqual(alert('hint'), { panelType: 'tip' })
+  for (const word of ['success', 'check', 'Done']) assert.deepEqual(alert(word), { panelType: 'success' }, word)
+  assert.deepEqual(alert('attention'), { panelType: 'warning' })
+  for (const word of ['danger', 'error', 'failure', 'fail', 'missing', 'BUG']) assert.deepEqual(alert(word), { panelType: 'error' }, word)
+  for (const word of ['info', 'note', 'question', 'my-type']) assert.deepEqual(alert(word), { panelType: 'info' }, word)
+})
+
+test('reads the rest of an alert marker line as the panel first body paragraph, the lines after as the next', () => {
+  assert.deepEqual(read('> [!NOTE]\n> Line **one**.\n>\n> Two.\n'), [panel('info', paragraph(text('Line '), text('one', strong), text('.')), said('Two.'))])
+  assert.deepEqual(read('> [!tip] Title\n'), [panel('tip', said('Title'))])
+  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('> > [!WARNING]\n> > Inner.\n'), [bare('blockquote', panel('warning', said('Inner.')))])
+})
+
+test('leaves a quote plain where its first line is no alert marker', () => {
+  for (const markdown of ['> \\[!NOTE]\n> x\n', '> [!NOTE]x\n', '> **[!NOTE]**\n', '> See [!NOTE]\n', '> [!NOTE]**x**\n', '> [!]\n', '> ```\n> [!NOTE]\n> ```\n']) {
+    const blocks = read(markdown)
+    assert.equal(typeof blocks !== 'string' && blocks[0]?.type, 'blockquote', markdown)
+  }
+})
+
+test('reads a folded callout to an expand titled by the rest of its marker line, whatever the word', () => {
+  assert.deepEqual(read('> [!NOTE]- Build log\n>\n> Line.\n'), [node('expand', { title: 'Build log' }, said('Line.'))])
+  assert.deepEqual(read('> [!bug]+ Open **by** default\n> body\n>\n> Line.\n'), [node('expand', { title: 'Open by default' }, said('body'), said('Line.'))])
+  const link: AdfMark = { attrs: { href: 'https://example.com' }, type: 'link' }
+  assert.deepEqual(read('> [!faq]- Why?\n> See [the docs](https://example.com), **now**.\n'), [
+    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('> [!NOTE]- Set ==x== here\n'), normal(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('- > [!NOTE]-\n'), normal(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()))))
+})
+
+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')))))
+})
+
+test('moves a nested task list beside its item and makes an item holding more than one block a block task item', () => {
+  assert.deepEqual(read('- [x] Parent\n  - [ ] Child\n- [ ] Next\n'), [bare('taskList', task('DONE', text('Parent')), bare('taskList', task('TODO', text('Child'))), task('TODO', text('Next')))])
+  assert.deepEqual(read('- [x] First.\n\n  Second.\n- [ ]\n\n  ```\n  x\n  ```\n'), [
+    bare('taskList', node('blockTaskItem', { state: 'DONE' }, said('First.'), said('Second.')), node('blockTaskItem', { state: 'TODO' }, bare('codeBlock', text('x')))),
+  ])
+  assert.deepEqual(read('- [x] A\n  - plain\n'), [bare('taskList', node('blockTaskItem', { state: 'DONE' }, said('A'), bare('bulletList', bare('listItem', said('plain')))))])
+})
+
+test('leaves mixed, ordered and unmarked lists plain', () => {
+  for (const markdown of ['- \\[x] a\n', '- [x] a\n- \\[ ] b\n', '- [x] a\n- b\n', '1. [x] a\n', '- [x]a\n', '- **[x]** a\n', '- [x]**a**\n', '- [-] a\n', '- > [x] a\n']) {
+    const blocks = read(markdown)
+    assert.notEqual(typeof blocks !== 'string' && blocks[0]?.type, 'taskList', markdown)
+    assert.equal(JSON.stringify(blocks).includes('taskItem'), false, markdown)
+  }
+  assert.deepEqual(read('- plain\n  - [ ] nested\n'), [bare('bulletList', bare('listItem', said('plain'), bare('taskList', task('TODO', text('nested')))))])
+})
+
+test('reads a == pair to the editor default highlight, Yellow200 #f8e6a0 in @atlaskit/adf-schema 57.6.8', () => {
+  assert.deepEqual(read('a ==hi there== b\n'), [paragraph(text('a '), text('hi there', highlight), text(' b'))])
+  assert.deepEqual(read('**==hi==** b\n'), [paragraph(text('hi', highlight, strong), text(' b'))])
+  assert.deepEqual(read('==**a**_b_ `c`==\n'), [paragraph(text('a', highlight, strong), text('b', highlight, em), text(' ', highlight), text('c', code))])
+  assert.deepEqual(read('==`a`==\n'), [paragraph(text('a', code))])
+  assert.deepEqual(read('x==y==z ==a == b==, (==c==) _d_==e==\n'), [paragraph(text('x==y==z '), text('a == b', highlight), text(', ('), text('c', highlight), text(') '), text('d', em), text('e', highlight))])
+  assert.deepEqual(read('😀==b== ==c==😀 é==d==\n'), [paragraph(text('😀'), text('b', highlight), text(' '), text('c', highlight), text('😀 é==d=='))])
+  assert.deepEqual(read('# ==h==\n\n| ==c== |\n| --- |\n'), [
+    node('heading', { level: 1 }, text('h', highlight)),
+    bare('table', bare('tableRow', bare('tableHeader', paragraph(text('c', highlight))))),
+  ])
+  assert.deepEqual(read('> [!NOTE]\n> ==x==\n'), [panel('info', paragraph(text('x', highlight)))])
+  assert.deepEqual(read('==a==\\\n==b==\n'), [paragraph(text('a', highlight), { type: 'hardBreak' }, text('b', highlight))])
+})
+
+test('leaves a == no pair flanks as text', () => {
+  for (const markdown of ['\\==x==\n', '==x\\==\n', 'a == b == c\n', 'if a==b and c==d then\n', 'a==b== c\n', '==a==b\n', '====\n', '`==x==`\n', '==a\\\nb==\n', '**==a**==\n', '==a', '== a==\n', '==a ==\n']) {
+    assert.equal(JSON.stringify(read(markdown)).includes('backgroundColor'), false, markdown)
+  }
+})
+
+test('reads what the reduction wrote back to the node it reduced, less the attributes it drops', () => {
+  const localId = '01a0d99b-1f59-7e2c-a3d4-62c1f0b8e7a1'
+  for (const panelType of ['info', 'note', 'tip', 'warning', 'error']) {
+    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(expand), [node('expand', { title: 'Log' }, said('Line.'), node('nestedExpand', { title: 'Inner' }, said('Deep.')))])
+  const tasks = bare(
+    'taskList',
+    node('taskItem', { localId, state: 'DONE' }, text('Write')),
+    bare('taskList', task('TODO', text('Review'))),
+    node('blockTaskItem', { state: 'TODO' }, said('First.'), said('Second.')),
+    node('blockTaskItem', { state: 'DONE' }, bare('codeBlock', text('x'))),
+  )
+  const plainTasks = bare(
+    'taskList',
+    task('DONE', text('Write')),
+    bare('taskList', task('TODO', text('Review'))),
+    node('blockTaskItem', { state: 'TODO' }, said('First.'), said('Second.')),
+    node('blockTaskItem', { state: 'DONE' }, bare('codeBlock', text('x'))),
+  )
+  assert.deepEqual(roundTripped(tasks), [plainTasks])
+  const colour: AdfMark = { attrs: { color: '#c6edfb' }, type: 'backgroundColor' }
+  assert.deepEqual(roundTripped(paragraph(text('a '), text('hi', colour, strong), text(' b'))), [paragraph(text('a '), text('hi', highlight, strong), text(' b'))])
+})
+
+test('keeps what markdownToAdf reads that no row reads, and refuses only what it refuses', () => {
+  assert.deepEqual(read('!adf:panel warning\n- [x] a\n!adf:/panel\n'), [panel('warning', bare('taskList', task('DONE', text('a'))))])
+  const future = bare('futureBlock', text('==x=='))
+  const carried = adfToMarkdown(document(future))
+  assert.deepEqual(carried.ok ? read(carried.value) : carried.error.code, [future])
+  const red: AdfMark = { attrs: { color: '#ff0000' }, type: 'backgroundColor' }
+  const held = paragraph(text('a ==b== c', red), text(' ==d '), { attrs: { note: 'x' }, text: 'e==f', type: 'text' }, text(' g=='))
+  const spelled = adfToMarkdown(document(held))
+  assert.deepEqual(spelled.ok ? read(spelled.value) : spelled.error.code, [paragraph(text('a ==b== c', red), text(' '), text('d ', highlight), { attrs: { note: 'x' }, text: 'e==f', type: 'text' }, text(' g', highlight))])
+  const lossless = markdownToAdf('> [!NOTE]\n\n- [x] ==a==\n')
+  assert.deepEqual(lossless.ok ? lossless.value.content : lossless.error.code, [bare('blockquote', said('[!NOTE]')), bare('bulletList', bare('listItem', said('[x] ==a==')))])
+  assert.equal(read('!adf:panel\n'), 'malformed-directive')
+  const refusal = (markdown: string): unknown => {
+    const parsed = plainMarkdownToAdf(markdown)
+    return parsed.ok ? parsed.value : [parsed.error.code, parsed.error.message]
+  }
+  for (const markdown of ['> [!tip] ![a](u)\n', '> [!NOTE]- ![a](u)\n', '- [x] ![a](u)\n']) {
+    assert.deepEqual(refusal(markdown), ['unmappable-image', 'an image fits only as a paragraph of its own: this one shares a line with a marker'], markdown)
+  }
+  for (const markdown of ['> [!tip]\n> ![a](u)\n', '> [!tip] t\n> ![a](u)\n', '> [!NOTE]- t\n> ![a](u)\n', '- [x]\n  ![a](u)\n']) {
+    assert.deepEqual(refusal(markdown), ['unmappable-image', 'an image fits only as a paragraph of its own: this one continues the paragraph a marker opens, which a blank line before it ends'], markdown)
+  }
+  let deep = 'x\n'
+  for (let level = 0; level < largestNesting; level += 1) deep = `> ${deep}`
+  assert.equal(typeof read(deep), 'object')
+})

src/markdown/plain-conventions.ts

@@ -1,3 +1,5 @@
+export type Flavour = 'lossless' | 'plain'
+
 type AlertMarker = { folded: boolean; length: number; panelType: string }
 
 export const foldedAlertMarker = '[!NOTE]-'

todo.md

@@ -4,26 +4,24 @@
 
 - **35 — Read and write plain markdown as a flavour of the markdown grammar.** Per Goal 2 and
   `docs/decisions.md` §Plain markdown is a flavour of the grammar, README §Plain markdown's rows are
-  read by `markdownToAdf`'s parser and written by `adfToMarkdown`'s writer, and the lift goes. The
+  read by `markdownToAdf`'s parser and written by `adfToMarkdown`'s writer. The
   exports, their refusals and those rows stay as they are.
-  - **35a — Read the plain flavour in the parser and delete the lift.** The rows are read while
-    parsing, and `plain-lift.ts` is deleted, its tests reading through `plainMarkdownToAdf`. `>
-    [!faq]- Why?` with the body on the next `>` line reads to an expand titled `Why?` whose body
-    keeps the next lines' link targets and marks, and `> [!tip] Title` then `> body` to a panel
-    whose paragraphs are `Title` and `body`: the rest of the marker's line is the title (an expand)
-    or the first body paragraph (a panel). A CommonMark backslash keeps a marker literal — `\==x==`,
-    `> \[!NOTE]`, `- \[x]`.
   - **35b — Spell the plain flavour in the writer.** Panels, expands, task lists and highlights are
     written by the writer, which escapes text that would read back as one, so
     `plainMarkdownToAdf(adfToPlainMarkdown(doc))` keeps a literal `==x==`, a quote opening `[!NOTE]`
     and a list whose items all open `[x] ` as text. A highlighted `=` (today `=====`) and `a==b`
     (today `==a==b==`, highlighting `a` alone) come back highlighted whole, or lose the highlight
     where no spelling holds them; the plain pair's byte-for-byte property misses both, since the
-    wrong document re-spells to the same bytes. The reduction keeps only degrading what the flavour
+    wrong document re-spells to the same bytes. An expand titled `**x** [y](z)` comes back an
-    cannot spell.
+    expand, where today its escaped marker reads back as a quote. The reduction keeps only
+    degrading what the flavour cannot spell.
 - **10f — Give task nodes read from plain markdown position ids.** Per `docs/decisions.md` §Plain
   task ids come from position, README §Plain markdown's `localId` bullet saying so. The id spelling
   is part of the chunk.
+- **41 — Keep a link's target when `plainMarkdownToAdf` reads a callout title.** Per Goal 5 a link
+  target is content, but `> [!faq]- See [x](http://y)` reads to an expand titled `See x`, the
+  target gone. Where the target goes is a gap in `docs/decisions.md`; candidate: the title keeps
+  it as text, `See x (http://y)`.
 - **40 — Make `markdownToAdf(adfToMarkdown(doc))` deep-equal `doc` for every document it takes.**
   Today it holds for editor-normal documents only: two adjacent text nodes with the same marks
   merge, an empty `attrs`, `marks` or `content` drops, and `-0` reads back `0` — shapes pipelines