Read the three directive forms, their attributes and the fences that nest them

AGENTS.md

@@ -87,7 +87,9 @@ cause; where one cause recurs across node types or across directions, one code c
 `path` and `message` say which — `unsupported-nesting-depth` is the 500-level guard whichever
 direction hits it. A claim code names the spelling claimed, never the node that spelling would have built:
 a malformed `:::table` is a `malformed-directive`. A cause the carry answers gets no code: a mark no
-spelling writes rides the carry with its node.
+spelling writes rides the carry with its node. A directive whose name reads back to no node is
+`unknown-directive-name` rather than a claim code — the spelling is well formed, and telling that
+apart from a typo is what a consumer switches on when a later MINOR gives the name meaning.
 
 ## 9. Release automation
 

corpus/errors/directive-fence-unclosed.error

@@ -0,0 +1 @@
+malformed-directive

corpus/errors/directive-fence-unclosed.md

@@ -0,0 +1,2 @@
+:::panel info
+Part.

corpus/errors/directive-inline-unclosed.error

@@ -0,0 +1 @@
+malformed-directive

corpus/errors/directive-inline-unclosed.md

@@ -0,0 +1 @@
+Part :mention[@A and more.

corpus/errors/directive-name-unknown.error

@@ -0,0 +1 @@
+unknown-directive-name

corpus/errors/directive-name-unknown.md

@@ -0,0 +1,3 @@
+:::widget info
+Part.
+:::

spec/flavour.md

@@ -87,11 +87,15 @@ least the opening's length, and a container's fence is longer than every directi
 anywhere in its body, however deeply a list item or blockquote nests it; a colon run inside a code
 fence or opaque carry is content. Canonical form uses minimal lengths.
 Directive fence lines follow code-fence indentation (up to three spaces relative to their
-container); trailing whitespace on a fence line is tolerated in input, never emitted.
+container).
 
 **Leaf block**: `::name arg {attrs}` — a block-position node with no body, `arg` reading as
 above.
 
+Canonical spacing is the only spacing input reads: one space parts the name, `arg` and `{attrs}`,
+and one parts each attribute pair, with no padding inside the braces. Trailing whitespace on a
+directive block line is tolerated in input, never emitted.
+
 **Claiming at block level**, symmetric with inline: a line whose leading run of two or more
 colons is followed immediately by a name character is claimed and must parse fully as a container
 opening or a leaf, else it is a named error. A bare colon-run line is a closing fence while a

src/markdown/directive-attributes.ts

@@ -1,47 +0,0 @@
-import type { JsonValue } from '../json-value.ts'
-import type { VocabularyPair } from '../adf/attribute-vocabulary.ts'
-import { serializeCanonicalJson } from '../canonical-json.ts'
-
-const bareToken = /^[A-Za-z0-9_-]+$/
-const inlineDirectiveOpener = /:[a-z][A-Za-z0-9]*[[{]/y
-
-// spec/flavour.md, Attributes.
-const quotedEscapes = /[&<`|]/g
-
-export function isBareToken(text: string): boolean {
-  return bareToken.test(text)
-}
-
-export function opensInlineDirective(text: string, index: number): boolean {
-  inlineDirectiveOpener.lastIndex = index
-  return inlineDirectiveOpener.test(text)
-}
-
-export function spellAttributes(pairs: readonly (readonly [string, string])[]): string {
-  if (pairs.length === 0) return ''
-  const spelled = [...pairs].sort(([left], [right]) => (left < right ? -1 : 1)).map(([key, value]) => `${key}=${value}`)
-  return `{${spelled.join(' ')}}`
-}
-
-export function spellVocabulary(pairs: readonly VocabularyPair[]): [string, string][] {
-  return pairs.map((pair): [string, string] => [pair.key, spellAttributeValue(pair)])
-}
-
-export function spellJsonAttribute(value: JsonValue): string {
-  return quote(serializeCanonicalJson(value, 'compact'))
-}
-
-export function spellStringAttribute(text: string): string {
-  return isBareToken(text) ? text : quote(text)
-}
-
-function spellAttributeValue(pair: VocabularyPair): string {
-  if (pair.kind === 'boolean') return `${pair.value}`
-  if (pair.kind === 'json') return spellJsonAttribute(pair.value)
-  if (pair.kind === 'number') return spellStringAttribute(JSON.stringify(pair.value))
-  return spellStringAttribute(pair.value)
-}
-
-function quote(text: string): string {
-  return JSON.stringify(text).replace(quotedEscapes, (character) => `\\u${character.charCodeAt(0).toString(16).padStart(4, '0')}`)
-}

src/markdown/directive-syntax.test.ts

@@ -0,0 +1,129 @@
+import assert from 'node:assert/strict'
+import test from 'node:test'
+
+import type { DirectiveLine } from './directive-syntax.ts'
+import { largestNesting } from '../nesting.ts'
+import { readDirectiveLine, readInlineDirective } from './directive-syntax.ts'
+
+function attributes(...pairs: [string, string][]): ReadonlyMap<string, string> {
+  return new Map(pairs)
+}
+
+function header(colons: number, name: string, argument?: string, ...pairs: [string, string][]): DirectiveLine {
+  return { argument, attributes: attributes(...pairs), colons, kind: 'header', name }
+}
+
+function fault(line: string): string {
+  const read = readDirectiveLine(line)
+  return read?.kind === 'fault' ? read.fault.message : `read ${JSON.stringify(read)}`
+}
+
+function inline(text: string): unknown {
+  const read = readInlineDirective(text, 0)
+  if (read === undefined) return 'unclaimed'
+  if (read.fault !== undefined) return read.fault.message
+  return { attributes: read.value.attributes, content: read.value.content, length: read.value.length, name: read.value.name }
+}
+
+function spans(text: string, name: string, content: string | undefined, ...pairs: [string, string][]): void {
+  assert.deepEqual(inline(text), { attributes: attributes(...pairs), content, length: text.length, name })
+}
+
+test('claims a colon-run line only where a name or nothing follows the colons', () => {
+  assert.equal(readDirectiveLine('Part.'), undefined)
+  assert.equal(readDirectiveLine(':: two'), undefined)
+  assert.equal(readDirectiveLine(':panel'), undefined)
+  assert.equal(readDirectiveLine('  ::rule'), undefined)
+})
+
+test('reads a bare colon run as the fence that closes a container', () => {
+  assert.deepEqual(readDirectiveLine(':::'), { colons: 3, kind: 'closing' })
+  assert.deepEqual(readDirectiveLine('::'), { colons: 2, kind: 'closing' })
+  assert.deepEqual(readDirectiveLine('::::::  \t'), { colons: 6, kind: 'closing' })
+})
+
+test('reads the leaf and container forms, their argument and their attributes', () => {
+  assert.deepEqual(readDirectiveLine('::rule'), header(2, 'rule'))
+  assert.deepEqual(readDirectiveLine('::rule  '), header(2, 'rule'))
+  assert.deepEqual(readDirectiveLine('::taskItem TODO'), header(2, 'taskItem', 'TODO'))
+  assert.deepEqual(readDirectiveLine('::hardBreak {}'), header(2, 'hardBreak'))
+  assert.deepEqual(readDirectiveLine('::media {id=a-1 type=file}'), header(2, 'media', undefined, ['id', 'a-1'], ['type', 'file']))
+  assert.deepEqual(readDirectiveLine('::panel info {panelColor="#ff0000"} '), header(2, 'panel', 'info', ['panelColor', '#ff0000']))
+  assert.deepEqual(readDirectiveLine(':::panel info'), header(3, 'panel', 'info'))
+})
+
+test('decodes a quoted attribute value, the escapes {attrs} reserves included', () => {
+  assert.deepEqual(readDirectiveLine('::extension {text="two words"}'), header(2, 'extension', undefined, ['text', 'two words']))
+  assert.deepEqual(readDirectiveLine('::extension {text="a\\u0060b\\u0026c\\u003cd\\u007ce"}'), header(2, 'extension', undefined, ['text', 'a`b&c<d|e']))
+  assert.deepEqual(readDirectiveLine('::extension {text="a\\"b\\\\c\\nd"}'), header(2, 'extension', undefined, ['text', 'a"b\\c\nd']))
+  assert.deepEqual(readDirectiveLine('::extension {text="}{"}'), header(2, 'extension', undefined, ['text', '}{']))
+})
+
+test('names the directive line no spelling reads', () => {
+  assert.equal(fault('::Panel'), 'a directive name reads [a-z][A-Za-z0-9]*')
+  assert.equal(fault('::1panel'), 'a directive name reads [a-z][A-Za-z0-9]*')
+  assert.equal(fault('::panel  info'), 'a directive line reads a name, one bare argument and {attrs}, one space apart')
+  assert.equal(fault('::panel info extra'), 'a directive line reads a name, one bare argument and {attrs}, one space apart')
+  assert.equal(fault('::panel{}'), 'a directive line reads a name, one bare argument and {attrs}, one space apart')
+  assert.equal(fault('::panel info{}'), 'a directive line reads a name, one bare argument and {attrs}, one space apart')
+  assert.equal(fault('::panel {} x'), 'a directive line reads a name, one bare argument and {attrs}, one space apart')
+})
+
+test('names the attributes no spelling reads', () => {
+  assert.equal(fault('::panel {a=1'), 'the {attrs} closing brace is missing')
+  assert.equal(fault('::panel {a="x}'), 'the {attrs} quoted value is unclosed')
+  assert.equal(fault('::panel {a="\\uzzzz"}'), 'the {attrs} quoted value is not a JSON string')
+  assert.equal(fault('::panel {a}'), 'an attribute reads key=value, the value bare or double-quoted')
+  assert.equal(fault('::panel {a=}'), 'an attribute reads key=value, the value bare or double-quoted')
+  assert.equal(fault('::panel {=1}'), 'an attribute reads key=value, the value bare or double-quoted')
+  assert.equal(fault('::panel {a=1  b=2}'), 'an attribute reads key=value, the value bare or double-quoted')
+  assert.equal(fault('::panel { a=1}'), 'an attribute reads key=value, the value bare or double-quoted')
+  assert.equal(fault('::panel {a=1 }'), 'an attribute reads key=value, the value bare or double-quoted')
+  assert.equal(fault('::panel {a=1 a=2}'), 'the attribute key a is spelled twice')
+})
+
+test('breaks the directive on the raw characters a quoted value spells as escapes', () => {
+  assert.equal(fault('::panel {a="x`y"}'), 'a raw ` inside {attrs} breaks the directive: spell it \\u0060')
+  assert.equal(fault('::panel {a="x&y"}'), 'a raw & inside {attrs} breaks the directive: spell it \\u0026')
+  assert.equal(fault('::panel {a="x<y"}'), 'a raw < inside {attrs} breaks the directive: spell it \\u003c')
+  assert.equal(fault('::panel {a="x|y"}'), 'a raw | inside {attrs} breaks the directive: spell it \\u007c')
+})
+
+test('reads an inline directive only where a bracket or a brace follows the name', () => {
+  assert.equal(inline('Part.'), 'unclaimed')
+  assert.equal(inline(':10:30'), 'unclaimed')
+  assert.equal(inline(':smile:'), 'unclaimed')
+  assert.equal(inline(':Mention[@A]'), 'unclaimed')
+  assert.equal(inline(':mention @A'), 'unclaimed')
+  spans(':mention[@A]', 'mention', '@A')
+  spans(':date{timestamp=1756080000000}', 'date', undefined, ['timestamp', '1756080000000'])
+  spans(':emoji[]{shortName=":tada:"}', 'emoji', '', ['shortName', ':tada:'])
+  spans(':underline[ a ]', 'underline', ' a ')
+})
+
+test('binds an inline directive as a unit, its content balancing brackets like link text', () => {
+  spans(':underline[a [b] c]', 'underline', 'a [b] c')
+  spans(':underline[a \\] b]', 'underline', 'a \\] b')
+  spans(':underline[a `]` b]', 'underline', 'a `]` b')
+  spans(':underline[a `b c]', 'underline', 'a `b c')
+  spans(':underline[:status[x]{color=red}]', 'underline', ':status[x]{color=red}')
+  spans(':status[x]{color=red style="bold "}', 'status', 'x', ['color', 'red'], ['style', 'bold '])
+  assert.deepEqual(inline(':underline[a]{}(b)'), { attributes: attributes(), content: 'a', length: 15, name: 'underline' })
+  assert.deepEqual(inline(':underline[a] {}'), { attributes: attributes(), content: 'a', length: 13, name: 'underline' })
+  assert.deepEqual(inline(':text{text=" "} and more'), { attributes: attributes(['text', ' ']), content: undefined, length: 15, name: 'text' })
+})
+
+test('names the inline directive left unclosed at the end of its line', () => {
+  assert.equal(inline(':mention[@A'), 'an inline directive [content] is unclosed')
+  assert.equal(inline(':mention[@A\nB]'), 'an inline directive [content] is unclosed')
+  assert.equal(inline(':mention[a `b\nc` d]'), 'an inline directive [content] is unclosed')
+  assert.equal(inline(':underline[:status[x'), 'an inline directive [content] is unclosed')
+  assert.equal(inline(':mention[@A]{id=1'), 'the {attrs} closing brace is missing')
+  assert.equal(inline(':mention{id=1'), 'the {attrs} closing brace is missing')
+})
+
+test('refuses inline directives nested deeper than the parser carries', () => {
+  const nest = (depth: number): string => `${':underline['.repeat(depth)}x${']'.repeat(depth)}`
+  spans(nest(largestNesting), 'underline', nest(largestNesting - 1))
+  assert.equal(inline(nest(largestNesting + 1)), `the input nests inline directives deeper than the ${largestNesting} levels the parser carries`)
+})

src/markdown/directive-syntax.ts

@@ -0,0 +1,250 @@
+import type { ConvertFault } from '../result.ts'
+import type { JsonValue } from '../json-value.ts'
+import type { VocabularyPair } from '../adf/attribute-vocabulary.ts'
+import { backslashEscape, claimsDirectiveLine } from './commonmark-grammar.ts'
+import { backtickRun, closingBacktickRun } from './backtick-runs.ts'
+import { largestNesting } from '../nesting.ts'
+import { runLength } from './emphasis-matching.ts'
+import { serializeCanonicalJson } from '../canonical-json.ts'
+
+export type DirectiveAttributes = ReadonlyMap<string, string>
+
+export type DirectiveLine =
+  | { argument: string | undefined; attributes: DirectiveAttributes; colons: number; kind: 'header'; name: string }
+  | { colons: number; kind: 'closing' }
+  | { fault: ConvertFault; kind: 'fault' }
+
+export type InlineDirective = { attributes: DirectiveAttributes; content: string | undefined; length: number; name: string }
+
+type Read<T> = { fault: ConvertFault; value?: undefined } | { fault?: undefined; value: T }
+
+type Attributes = { attributes: DirectiveAttributes; length: number }
+
+type AttributePair = { end: number; key: string; value: string }
+
+const bareTokenSource = '[A-Za-z0-9_-]+'
+const bareRun = new RegExp(bareTokenSource, 'y')
+const bareToken = new RegExp(`^${bareTokenSource}$`)
+const directiveName = /[a-z][A-Za-z0-9]*/y
+const inlineDirectiveOpener = /:[a-z][A-Za-z0-9]*[[{]/y
+const lineEnd = /^[ \t]*$/
+// spec/flavour.md, Attributes.
+const reservedSource = '[&<`|]'
+const quotedEscapes = new RegExp(reservedSource, 'g')
+const rawReserved = new RegExp(reservedSource)
+const noAttributes: DirectiveAttributes = new Map()
+
+const nameFault = 'a directive name reads [a-z][A-Za-z0-9]*'
+const pairFault = 'an attribute reads key=value, the value bare or double-quoted'
+const shapeFault = 'a directive line reads a name, one bare argument and {attrs}, one space apart'
+
+export function isBareToken(text: string): boolean {
+  return bareToken.test(text)
+}
+
+export function malformedDirective(message: string): ConvertFault {
+  return { code: 'malformed-directive', message }
+}
+
+export function opensInlineDirective(text: string, index: number): boolean {
+  return inlineDirectiveName(text, index) !== undefined
+}
+
+export function readDirectiveLine(line: string): DirectiveLine | undefined {
+  if (!claimsDirectiveLine(line)) return undefined
+  const colons = runLength(line, 0)
+  const rest = line.slice(colons)
+  if (lineEnd.test(rest)) return { colons, kind: 'closing' }
+  const header = readDirectiveHeader(rest)
+  if (header.fault !== undefined) return { fault: header.fault, kind: 'fault' }
+  return { argument: header.value.argument, attributes: header.value.attributes, colons, kind: 'header', name: header.value.name }
+}
+
+export function readInlineDirective(text: string, index: number): Read<InlineDirective> | undefined {
+  return readNestedDirective(text, index, 1)
+}
+
+export function spellAttributes(pairs: readonly (readonly [string, string])[]): string {
+  if (pairs.length === 0) return ''
+  const spelled = [...pairs].sort(([left], [right]) => (left < right ? -1 : 1)).map(([key, value]) => `${key}=${value}`)
+  return `{${spelled.join(' ')}}`
+}
+
+export function spellJsonAttribute(value: JsonValue): string {
+  return quote(serializeCanonicalJson(value, 'compact'))
+}
+
+export function spellStringAttribute(text: string): string {
+  return isBareToken(text) ? text : quote(text)
+}
+
+export function spellVocabulary(pairs: readonly VocabularyPair[]): [string, string][] {
+  return pairs.map((pair): [string, string] => [pair.key, spellAttributeValue(pair)])
+}
+
+export function unknownDirectiveFault(name: string): ConvertFault {
+  return { code: 'unknown-directive-name', message: `the directive name ${name} reads back to no node` }
+}
+
+function spellAttributeValue(pair: VocabularyPair): string {
+  if (pair.kind === 'boolean') return `${pair.value}`
+  if (pair.kind === 'json') return spellJsonAttribute(pair.value)
+  if (pair.kind === 'number') return spellStringAttribute(JSON.stringify(pair.value))
+  return spellStringAttribute(pair.value)
+}
+
+function quote(text: string): string {
+  return JSON.stringify(text).replace(quotedEscapes, (character) => `\\u${escapeDigits(character)}`)
+}
+
+function escapeDigits(character: string): string {
+  return character.charCodeAt(0).toString(16).padStart(4, '0')
+}
+
+function inlineDirectiveName(text: string, index: number): string | undefined {
+  inlineDirectiveOpener.lastIndex = index
+  const opened = inlineDirectiveOpener.exec(text)?.[0]
+  return opened === undefined ? undefined : opened.slice(1, -1)
+}
+
+function readDirectiveHeader(rest: string): Read<{ argument: string | undefined; attributes: DirectiveAttributes; name: string }> {
+  directiveName.lastIndex = 0
+  const name = directiveName.exec(rest)?.[0]
+  if (name === undefined) return { fault: malformedDirective(nameFault) }
+  let cursor = name.length
+  let argument: string | undefined
+  let attributes = noAttributes
+  if (rest.charAt(cursor) === ' ' && rest.charAt(cursor + 1) !== '{' && !lineEnd.test(rest.slice(cursor))) {
+    bareRun.lastIndex = cursor + 1
+    argument = bareRun.exec(rest)?.[0]
+    if (argument === undefined) return { fault: malformedDirective(shapeFault) }
+    cursor += 1 + argument.length
+  }
+  if (rest.charAt(cursor) === ' ' && rest.charAt(cursor + 1) === '{') {
+    const read = readAttributes(rest, cursor + 1)
+    if (read.fault !== undefined) return { fault: read.fault }
+    attributes = read.value.attributes
+    cursor += 1 + read.value.length
+  }
+  if (!lineEnd.test(rest.slice(cursor))) return { fault: malformedDirective(shapeFault) }
+  return { value: { argument, attributes, name } }
+}
+
+function readNestedDirective(text: string, index: number, depth: number): Read<InlineDirective> | undefined {
+  const name = inlineDirectiveName(text, index)
+  if (name === undefined) return undefined
+  if (depth > largestNesting) {
+    return { fault: { code: 'unsupported-nesting-depth', message: `the input nests inline directives deeper than the ${largestNesting} levels the parser carries` } }
+  }
+  let cursor = index + 1 + name.length
+  let content: string | undefined
+  if (text.charAt(cursor) === '[') {
+    const end = readDirectiveContent(text, cursor + 1, depth)
+    if (end.fault !== undefined) return { fault: end.fault }
+    content = text.slice(cursor + 1, end.value)
+    cursor = end.value + 1
+  }
+  let attributes = noAttributes
+  if (text.charAt(cursor) === '{') {
+    const read = readAttributes(text, cursor)
+    if (read.fault !== undefined) return { fault: read.fault }
+    attributes = read.value.attributes
+    cursor += read.value.length
+  }
+  return { value: { attributes, content, length: cursor - index, name } }
+}
+
+// Where the content's own closing bracket sits: a code span, an escape and a nested directive each bind before it.
+function readDirectiveContent(text: string, start: number, depth: number): Read<number> {
+  let brackets = 0
+  let cursor = start
+  while (cursor < text.length && text.charAt(cursor) !== '\n') {
+    const character = text.charAt(cursor)
+    if (character === '\\') {
+      cursor += backslashEscape(text, cursor) === undefined ? 1 : 2
+      continue
+    }
+    if (character === '`') {
+      const span = readCodeSpanEnd(text, cursor)
+      if (span === undefined) break
+      cursor = span
+      continue
+    }
+    const nested = character === ':' ? readNestedDirective(text, cursor, depth + 1) : undefined
+    if (nested !== undefined) {
+      if (nested.fault !== undefined) return { fault: nested.fault }
+      cursor += nested.value.length
+      continue
+    }
+    if (character === ']' && brackets === 0) return { value: cursor }
+    if (character === '[') brackets += 1
+    if (character === ']') brackets -= 1
+    cursor += 1
+  }
+  return { fault: malformedDirective('an inline directive [content] is unclosed') }
+}
+
+// `undefined` where the span crosses the line ending an inline directive may not cross.
+function readCodeSpanEnd(text: string, index: number): number | undefined {
+  const opener = backtickRun(text, index)
+  const closer = closingBacktickRun(text, index + opener, opener)
+  if (closer === undefined) return index + opener
+  return text.slice(index, closer + opener).includes('\n') ? undefined : closer + opener
+}
+
+function readAttributes(text: string, index: number): Read<Attributes> {
+  const attributes = new Map<string, string>()
+  let cursor = index + 1
+  while (cursor < text.length && text.charAt(cursor) !== '}') {
+    if (attributes.size > 0) {
+      if (text.charAt(cursor) !== ' ') return { fault: malformedDirective(pairFault) }
+      cursor += 1
+    }
+    const pair = readAttributePair(text, cursor)
+    if (pair.fault !== undefined) return { fault: pair.fault }
+    if (attributes.has(pair.value.key)) return { fault: malformedDirective(`the attribute key ${pair.value.key} is spelled twice`) }
+    attributes.set(pair.value.key, pair.value.value)
+    cursor = pair.value.end
+  }
+  if (text.charAt(cursor) !== '}') return { fault: malformedDirective('the {attrs} closing brace is missing') }
+  return { value: { attributes, length: cursor + 1 - index } }
+}
+
+function readAttributePair(text: string, index: number): Read<AttributePair> {
+  bareRun.lastIndex = index
+  const key = bareRun.exec(text)?.[0]
+  if (key === undefined || text.charAt(index + key.length) !== '=') return { fault: malformedDirective(pairFault) }
+  const start = index + key.length + 1
+  if (text.charAt(start) === '"') {
+    const quoted = readQuotedValue(text, start)
+    if (quoted.fault !== undefined) return { fault: quoted.fault }
+    return { value: { end: quoted.value.end, key, value: quoted.value.value } }
+  }
+  bareRun.lastIndex = start
+  const value = bareRun.exec(text)?.[0]
+  if (value === undefined) return { fault: malformedDirective(pairFault) }
+  return { value: { end: start + value.length, key, value } }
+}
+
+function readQuotedValue(text: string, index: number): Read<{ end: number; value: string }> {
+  let cursor = index + 1
+  while (cursor < text.length && text.charAt(cursor) !== '"') cursor += text.charAt(cursor) === '\\' ? 2 : 1
+  if (text.charAt(cursor) !== '"') return { fault: malformedDirective('the {attrs} quoted value is unclosed') }
+  const raw = text.slice(index, cursor + 1)
+  const character = rawReserved.exec(raw)?.[0]
+  if (character !== undefined) {
+    return { fault: malformedDirective(`a raw ${character} inside {attrs} breaks the directive: spell it \\u${escapeDigits(character)}`) }
+  }
+  const value = parseJsonString(raw)
+  if (value === undefined) return { fault: malformedDirective('the {attrs} quoted value is not a JSON string') }
+  return { value: { end: cursor + 1, value } }
+}
+
+function parseJsonString(raw: string): string | undefined {
+  try {
+    const value: unknown = JSON.parse(raw)
+    return typeof value === 'string' ? value : undefined
+  } catch {
+    return undefined
+  }
+}

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

@@ -2,7 +2,7 @@ import type { AdfMark, AdfNode } from '../../adf/document.ts'
 import type { BlockDirective } from '../../adf/block-directives.ts'
 import type { JsonValue } from '../../json-value.ts'
 import { blockArgument } from '../block-directive-arguments.ts'
-import { isBareToken, spellAttributes, spellJsonAttribute, spellVocabulary } from '../directive-attributes.ts'
+import { isBareToken, spellAttributes, spellJsonAttribute, spellVocabulary } from '../directive-syntax.ts'
 import { vocabularyPairs } from '../../adf/attribute-vocabulary.ts'
 
 export function spellDirectiveHeader(node: AdfNode, directive: BlockDirective, spelledByBody: readonly string[] = []): string | undefined {

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

@@ -1,6 +1,6 @@
 import type { AdfNode } from '../../adf/document.ts'
 import type { InlineDirective } from '../../adf/inline-directives.ts'
-import { spellAttributes, spellVocabulary } from '../directive-attributes.ts'
+import { spellAttributes, spellVocabulary } from '../directive-syntax.ts'
 import { vocabularyPairs } from '../../adf/attribute-vocabulary.ts'
 
 export function spellInlineNodeAttributes(node: AdfNode, directive: InlineDirective): string | undefined {

src/markdown/emit/inline-line.ts

@@ -10,7 +10,7 @@ import { largestNesting } from '../../nesting.ts'
 import { longestBacktickRun } from '../backtick-runs.ts'
 import { markSpelling, spellMarkAttributes } from '../mark-spellings.ts'
 import { sameMark } from '../../adf/editor-normal.ts'
-import { spellAttributes, spellStringAttribute } from '../directive-attributes.ts'
+import { spellAttributes, spellStringAttribute } from '../directive-syntax.ts'
 import { spellDestination, spellTitle } from '../link-syntax.ts'
 import { spellInlineNodeAttributes } from './inline-directive-spelling.ts'
 

src/markdown/emit/line-escaping.ts

@@ -1,7 +1,7 @@
 import { backtickRun, closingBacktickRun } from '../backtick-runs.ts'
 import { delimiterFlags, isWordCharacter, matchEmphasis, runLength } from '../emphasis-matching.ts'
 import { backslashEscape, escapesLineClaim, inlineHtmlConstruct, opensBracketedAutolink, opensEmailAutolink, type LinePosition } from '../commonmark-grammar.ts'
-import { opensInlineDirective } from '../directive-attributes.ts'
+import { opensInlineDirective } from '../directive-syntax.ts'
 import { readEntityReference } from '../entity-references.ts'
 
 export type EmphasisRole = 'close' | 'open'

src/markdown/mark-spellings.ts

@@ -2,7 +2,7 @@ import type { AdfMark } from '../adf/document.ts'
 import type { AttributeVocabulary } from '../adf/attribute-vocabulary.ts'
 import type { MarkType } from '../adf/mark-attributes.ts'
 import { isMarkType, markAttributes } from '../adf/mark-attributes.ts'
-import { spellAttributes, spellVocabulary } from './directive-attributes.ts'
+import { spellAttributes, spellVocabulary } from './directive-syntax.ts'
 import { vocabularyPairs } from '../adf/attribute-vocabulary.ts'
 
 type Spelling = { kind: 'code' | 'directive' | 'link'; spelling?: undefined } | { kind: 'emphasis'; spelling: string }

src/markdown/opaque-carry.ts

@@ -5,7 +5,7 @@ import { isJsonValue } from '../json-value.ts'
 import { fencedCodeBlock } from './backtick-runs.ts'
 import { largestNesting } from '../nesting.ts'
 import { serializeCanonicalJson } from '../canonical-json.ts'
-import { spellAttributes, spellStringAttribute } from './directive-attributes.ts'
+import { spellAttributes, spellStringAttribute } from './directive-syntax.ts'
 
 export const carryName = 'adf'
 

src/markdown/parse/blocks.test.ts

@@ -1,6 +1,7 @@
 import assert from 'node:assert/strict'
 import test from 'node:test'
 
+import type { Block } from './blocks.ts'
 import type { LinkDefinition } from '../link-syntax.ts'
 import { parseBlocks } from './blocks.ts'
 
@@ -12,6 +13,20 @@ function kinds(markdown: string): string[] {
   return parseBlocks(markdown).blocks.map((block) => block.kind)
 }
 
+function faults(markdown: string): string[] {
+  const messages: string[] = []
+  const walk = (blocks: readonly Block[]): void => {
+    for (const block of blocks) {
+      if (block.kind === 'fault') messages.push(block.fault.message)
+      if (block.kind === 'blockquote') walk(block.blocks)
+      if (block.kind === 'directive' && block.blocks !== undefined) walk(block.blocks)
+      if (block.kind === 'bulletList' || block.kind === 'orderedList') for (const item of block.items) walk(item)
+    }
+  }
+  walk(parseBlocks(markdown).blocks)
+  return messages
+}
+
 test('keeps the link reference definitions a paragraph gives up, the first of a label winning', () => {
   assert.deepEqual(definitions('[a]: /url\n'), [['a', { destination: '/url' }]])
   assert.deepEqual(definitions('[Foo  Bar]:\n<the url>\n"Title"\n'), [['foo bar', { destination: 'the url', title: 'Title' }]])
@@ -61,6 +76,23 @@ test('swallows an HTML block to the end condition its start sets', () => {
 })
 
 test('carries a claimed line as the block it opens, the refusal the node layer builds', () => {
-  assert.deepEqual(kinds(':::\nPart.\n'), ['claim', 'paragraph'])
+  assert.deepEqual(kinds(':::\nPart.\n'), ['fault', 'paragraph'])
-  assert.deepEqual(kinds('Part.\n| x |\n'), ['paragraph', 'claim'])
+  assert.deepEqual(kinds('Part.\n| x |\n'), ['paragraph', 'fault'])
+})
+
+test('holds a directive container open until the fence that closes it', () => {
+  assert.deepEqual(kinds(':::panel info\nPart.\n:::\nMore.\n'), ['directive', 'paragraph'])
+  assert.deepEqual(kinds('::rule\nPart.\n'), ['directive', 'paragraph'])
+  assert.deepEqual(faults(':::panel info\n\nPart.\n\n:::\n'), [])
+  assert.deepEqual(faults(':::panel info\n> Part.\n> :::\n'), [])
+  assert.deepEqual(faults('::::panel info\n- :::expand\n  Part.\n  :::\n::::\n'), [])
+  assert.deepEqual(faults(':::panel info\n```\n:::\n```\n:::\n'), [])
+})
+
+test('names the directive fence a container does not sit longer than', () => {
+  assert.deepEqual(faults(':::panel info\n:::expand\nPart.\n:::\n'), ["a directive fence line is at least as long as the container's 3 colons"])
+  assert.deepEqual(faults('::::panel info\n:::\n::::\n'), ['a closing fence is shorter than the 4 colons it would close'])
+  assert.deepEqual(faults(':::panel info\nPart.\n'), ['a container fenced with 3 colons is unclosed'])
+  assert.deepEqual(faults('- :::panel info\n\nPart.\n'), ['a container fenced with 3 colons is unclosed'])
+  assert.deepEqual(faults('Part.\n\n:::\n'), ['a closing fence closes no open container'])
 })

src/markdown/parse/blocks.ts

@@ -1,3 +1,5 @@
+import type { ConvertFault } from '../../result.ts'
+import type { DirectiveAttributes, DirectiveLine } from '../directive-syntax.ts'
 import type { LinkDefinition } from '../link-syntax.ts'
 import {
   atxHeading,
@@ -12,14 +14,14 @@ import {
   openingHtmlBlock,
   setextHeadingLevel,
 } from '../commonmark-grammar.ts'
+import { malformedDirective, readDirectiveLine } from '../directive-syntax.ts'
 import { readLinkDefinitions } from './link-reference-definitions.ts'
 
-export type ClaimedConstruct = 'directive' | 'pipe-table'
-
 export type Block =
+  | { argument: string | undefined; attributes: DirectiveAttributes; blocks: Block[] | undefined; kind: 'directive'; name: string }
   | { blocks: Block[]; kind: 'blockquote' }
-  | { construct: ClaimedConstruct; kind: 'claim' }
   | { construct: string; kind: 'html' }
+  | { fault: ConvertFault; kind: 'fault' }
   | { items: Block[][]; kind: 'bulletList' }
   | { items: Block[][]; kind: 'orderedList'; start: number }
   | { kind: 'code'; language: string; text: string }
@@ -29,9 +31,16 @@ export type Block =
 
 export type ParsedBlocks = { blocks: Block[]; definitions: Map<string, LinkDefinition> }
 
+type DirectiveBlock = Extract<Block, { kind: 'directive' }>
+
 type ListBlock = Extract<Block, { items: Block[][] }>
 
-type OpenContainer = Extract<Block, { kind: 'blockquote' }> | { blocks: Block[]; indentation: number; kind: 'item'; list: ListBlock; marker: string }
+type OpenDirective = { blocks: Block[]; colons: number; index: number; kind: 'directive'; parent: Block[] }
+
+type OpenContainer =
+  | Extract<Block, { kind: 'blockquote' }>
+  | OpenDirective
+  | { blocks: Block[]; indentation: number; kind: 'item'; list: ListBlock; marker: string }
 
 type OpenLeaf =
   | { closer: RegExp | undefined; construct: string; kind: 'html' }
@@ -49,12 +58,13 @@ type Walk = ParsedBlocks & { leaf: OpenLeaf | undefined; stack: OpenContainer[]
 const blankLine = /^[ \t]*$/
 const indentedCodeColumns = 4
 const largestOpenerIndentation = 3
+const leafColons = 2
 const tabStop = 4
 
 export function parseBlocks(markdown: string): ParsedBlocks {
   const walk: Walk = { blocks: [], definitions: new Map(), leaf: undefined, stack: [] }
   for (const text of normalizeInput(markdown).split('\n')) readLine(walk, { column: 0, text })
-  closeLeaf(walk)
+  closeContainers(walk, 0)
   return { blocks: walk.blocks, definitions: walk.definitions }
 }
 
@@ -95,6 +105,8 @@ function matchContainers(walk: Walk, line: Line): { depth: number; rest: Line }
 
 function continuesContainer(walk: Walk, container: OpenContainer, line: Line): Line | undefined {
   if (container.kind === 'blockquote') return blockquoteRest(removeColumns(line, largestOpenerIndentation))
+  // A directive container has no continuation marker: only its own fence closes it.
+  if (container.kind === 'directive') return line
   // A list item begins with at most one blank line: an empty one gives the second up.
   if (blankLine.test(line.text)) {
     return container.blocks.length === 0 && walk.leaf === undefined ? undefined : { column: line.column, text: '' }
@@ -169,7 +181,65 @@ function openContainer(walk: Walk, start: ContainerStart): void {
 
 function closeContainers(walk: Walk, depth: number): void {
   closeLeaf(walk)
-  walk.stack.length = depth
+  for (const container of walk.stack.splice(depth)) {
+    if (container.kind !== 'directive') continue
+    container.parent[container.index] = { fault: malformedDirective(`a container fenced with ${container.colons} colons is unclosed`), kind: 'fault' }
+  }
+}
+
+function openDirective(walk: Walk, directive: Extract<DirectiveLine, { kind: 'header' }>): void {
+  const block: DirectiveBlock = {
+    argument: directive.argument,
+    attributes: directive.attributes,
+    blocks: directive.colons > leafColons ? [] : undefined,
+    kind: 'directive',
+    name: directive.name,
+  }
+  const parent = currentBlocks(walk)
+  parent.push(block)
+  if (block.blocks !== undefined) walk.stack.push({ blocks: block.blocks, colons: directive.colons, index: parent.length - 1, kind: 'directive', parent })
+}
+
+function readDirective(walk: Walk, directive: DirectiveLine): void {
+  closeLeaf(walk)
+  if (directive.kind === 'fault') {
+    pushFault(walk, directive.fault)
+    return
+  }
+  const enclosing = innermostDirective(walk)
+  if (directive.kind === 'closing') {
+    closeDirective(walk, directive.colons, enclosing)
+    return
+  }
+  if (enclosing !== undefined && directive.colons >= enclosing.container.colons) {
+    pushFault(walk, malformedDirective(`a directive fence line is at least as long as the container's ${enclosing.container.colons} colons`))
+    return
+  }
+  openDirective(walk, directive)
+}
+
+function closeDirective(walk: Walk, colons: number, enclosing: { container: OpenDirective; depth: number } | undefined): void {
+  if (enclosing === undefined) {
+    pushFault(walk, malformedDirective('a closing fence closes no open container'))
+    return
+  }
+  if (colons < enclosing.container.colons) {
+    pushFault(walk, malformedDirective(`a closing fence is shorter than the ${enclosing.container.colons} colons it would close`))
+    return
+  }
+  walk.stack.length = enclosing.depth
+}
+
+function innermostDirective(walk: Walk): { container: OpenDirective; depth: number } | undefined {
+  for (let depth = walk.stack.length - 1; depth >= 0; depth -= 1) {
+    const container = walk.stack[depth]
+    if (container?.kind === 'directive') return { container, depth }
+  }
+  return undefined
+}
+
+function pushFault(walk: Walk, fault: ConvertFault): void {
+  currentBlocks(walk).push({ fault, kind: 'fault' })
 }
 
 // A claimed line ends the lazy continuation CommonMark would fold it into (spec/flavour.md).
@@ -177,7 +247,7 @@ function continuesLazily(walk: Walk, line: Line): boolean {
   if (walk.leaf?.kind !== 'paragraph' || blankLine.test(line.text)) return false
   if (leadingColumns(line) >= indentedCodeColumns) return true
   const opener = removeColumns(line, largestOpenerIndentation).text
-  if (claimedConstruct(opener) !== undefined || isThematicBreak(opener)) return false
+  if (claimsDirectiveLine(opener) || claimsPipeLine(opener) || isThematicBreak(opener)) return false
   return atxHeading(opener) === undefined && openingCodeFence(opener) === undefined && openingHtmlBlock(opener, true) === undefined
 }
 
@@ -220,10 +290,14 @@ function readIndentedCodeLine(leaf: Extract<OpenLeaf, { kind: 'indented-code' }>
 
 function openLeaf(walk: Walk, line: Line): void {
   const opener = removeColumns(line, largestOpenerIndentation).text
-  const claimed = claimedConstruct(opener)
+  const directive = readDirectiveLine(opener)
-  if (claimed !== undefined) {
+  if (directive !== undefined) {
+    readDirective(walk, directive)
+    return
+  }
+  if (claimsPipeLine(opener)) {
     closeLeaf(walk)
-    currentBlocks(walk).push({ construct: claimed, kind: 'claim' })
+    pushFault(walk, { code: 'malformed-pipe-table', message: 'the line claims a pipe table and parses as none' })
     return
   }
   if (readLineBlock(walk, opener)) return
@@ -297,11 +371,6 @@ function currentBlocks(walk: Walk): Block[] {
   return walk.stack.at(-1)?.blocks ?? walk.blocks
 }
 
-function claimedConstruct(opener: string): ClaimedConstruct | undefined {
-  if (claimsDirectiveLine(opener)) return 'directive'
-  return claimsPipeLine(opener) ? 'pipe-table' : undefined
-}
-
 function normalizeInput(markdown: string): string {
   return markdown
     .replace(/\r\n?/g, '\n')

src/markdown/parse/inline-content.ts

@@ -7,6 +7,7 @@ import { delimiterFlags, matchEmphasis, runLength } from '../emphasis-matching.t
 import { failure, success, type ConvertErrorPath, type Result } from '../../result.ts'
 import { mergeAdjacentText } from '../../adf/editor-normal.ts'
 import { normalizeLabel, readInlineTarget, readLabel } from '../link-syntax.ts'
+import { readInlineDirective, unknownDirectiveFault } from '../directive-syntax.ts'
 
 export type InlineContent = { image: AdfNode; nodes?: undefined } | { image?: undefined; nodes: AdfNode[] }
 
@@ -50,6 +51,12 @@ export function parseInlineContent(source: string, definitions: LinkDefinitions,
         index = angle.value
         break
       }
+      case ':': {
+        const directive = readDirective(scan, index)
+        if (!directive.ok) return directive
+        index = directive.value
+        break
+      }
       case '!':
       case '[':
         index = openBracket(scan, index)
@@ -131,6 +138,16 @@ function openBracket(scan: Scan, index: number): number {
   return index + width
 }
 
+function readDirective(scan: Scan, index: number): Result<number> {
+  const directive = readInlineDirective(scan.source, index)
+  if (directive === undefined) {
+    scan.pending += ':'
+    return success(index + 1)
+  }
+  const fault = directive.fault ?? unknownDirectiveFault(directive.value.name)
+  return failure(fault.code, fault.message, scan.path)
+}
+
 function flush(scan: Scan, strip: boolean): void {
   const raw = strip ? scan.pending.replace(trailingSpace, '') : scan.pending
   scan.pending = ''

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

@@ -128,13 +128,33 @@ test('reads an indented code block where no paragraph is open', () => {
 
 test('claims a block-level colon run with no directive to parse it', () => {
   assert.equal(code(markdownToAdf(':::\n')), 'malformed-directive')
-  assert.equal(code(markdownToAdf('::panel\n')), 'malformed-directive')
+  assert.equal(code(markdownToAdf('::Panel\n')), 'malformed-directive')
-  assert.equal(code(markdownToAdf('   :::panel info\nx\n:::\n')), 'malformed-directive')
+  assert.equal(code(markdownToAdf('::panel {a=1 a=2}\n')), 'malformed-directive')
   assert.deepEqual(path(markdownToAdf('Part.\n:::x\n')), ['content', 1])
   assert.deepEqual(content(markdownToAdf(':10:30\n')), [paragraph(':10:30')])
   assert.deepEqual(content(markdownToAdf(':: two\n')), [paragraph(':: two')])
 })
 
+test('reads the three directive forms, and names the node none of them reads back to', () => {
+  assert.equal(code(markdownToAdf('::rule\n')), 'unknown-directive-name')
+  assert.equal(code(markdownToAdf('   :::panel info\nx\n:::\n')), 'unknown-directive-name')
+  assert.equal(code(markdownToAdf('Part :mention[@A]{id=b1c2}.\n')), 'unknown-directive-name')
+  assert.equal(content(markdownToAdf('::rule\n')), 'unknown-directive-name: the directive name rule reads back to no node')
+  assert.deepEqual(path(markdownToAdf('Part.\n\n::rule\n')), ['content', 1])
+})
+
+test('leaves the colon that opens no directive the text it is', () => {
+  assert.deepEqual(content(markdownToAdf('At 10:30 :smile: today.\n')), [paragraph('At 10:30 :smile: today.')])
+  assert.deepEqual(content(markdownToAdf('\\:mention[@A]\n')), [paragraph(':mention[@A]')])
+  assert.deepEqual(content(markdownToAdf('`:mention[@A]`\n')), [{ content: [codeSpan(':mention[@A]')], type: 'paragraph' }])
+})
+
+test('names the inline directive left unclosed at the end of its line', () => {
+  assert.equal(code(markdownToAdf('Part :mention[@A\n')), 'malformed-directive')
+  assert.equal(code(markdownToAdf('Part :mention[@A]{id=\n')), 'malformed-directive')
+  assert.deepEqual(path(markdownToAdf('> Part :mention[@A\n')), ['content', 0, 'content', 0])
+})
+
 test('claims a block-level pipe with no table to parse it', () => {
   assert.equal(code(markdownToAdf('| Part | Qty |\n')), 'malformed-pipe-table')
   assert.deepEqual(content(markdownToAdf('\\| Part\n')), [paragraph('| Part')])

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

@@ -1,10 +1,11 @@
 import type { AdfDocument, AdfNode } from '../../adf/document.ts'
-import type { Block, ClaimedConstruct } from './blocks.ts'
+import type { Block } from './blocks.ts'
 import type { LinkDefinitions } from './inline-content.ts'
 import { failure, success, type ConvertErrorPath, type Result } from '../../result.ts'
 import { largestNesting } from '../../nesting.ts'
 import { parseBlocks } from './blocks.ts'
 import { parseInlineContent } from './inline-content.ts'
+import { unknownDirectiveFault } from '../directive-syntax.ts'
 
 export function markdownToAdf(markdown: string): Result<AdfDocument> {
   const parsed = parseBlocks(markdown)
@@ -30,10 +31,14 @@ function blockNode(block: Block, definitions: LinkDefinitions, path: ConvertErro
       return containerNode({ type: 'blockquote' }, block.blocks, definitions, path, depth)
     case 'bulletList':
       return listNode({ type: 'bulletList' }, block.items, definitions, path, depth)
-    case 'claim':
-      return claimFailure(block.construct, path)
     case 'code':
       return success(codeBlockNode(block.language, block.text))
+    case 'directive': {
+      const fault = unknownDirectiveFault(block.name)
+      return failure(fault.code, fault.message, path)
+    }
+    case 'fault':
+      return failure(block.fault.code, block.fault.message, path)
     case 'heading':
       return contentNode({ attrs: { level: block.level }, type: 'heading' }, block.text, definitions, path)
     case 'html':
@@ -63,15 +68,6 @@ function listNode(node: AdfNode, items: readonly Block[][], definitions: LinkDef
   return success({ ...node, content })
 }
 
-function claimFailure(construct: ClaimedConstruct, path: ConvertErrorPath): Result<AdfNode> {
-  switch (construct) {
-    case 'directive':
-      return failure('malformed-directive', 'the line claims a directive and parses as none', path)
-    case 'pipe-table':
-      return failure('malformed-pipe-table', 'the line claims a pipe table and parses as none', path)
-  }
-}
-
 function codeBlockNode(language: string, text: string): AdfNode {
   const node: AdfNode = language === '' ? { type: 'codeBlock' } : { attrs: { language }, type: 'codeBlock' }
   return text === '' ? node : { ...node, content: [{ text, type: 'text' }] }

src/result.ts

@@ -2,6 +2,7 @@ export type ConvertErrorCode =
   | 'malformed-directive'
   | 'malformed-pipe-table'
   | 'not-an-adf-document'
+  | 'unknown-directive-name'
   | 'unmappable-html'
   | 'unmappable-image'
   | 'unspellable-adjacent-lists'
@@ -17,12 +18,13 @@ export type ConvertErrorCode =
 
 export type ConvertErrorPath = readonly (number | string)[]
 
-export type ConvertError = {
+export type ConvertFault = {
   code: ConvertErrorCode
   message: string
-  path: ConvertErrorPath
 }
 
+export type ConvertError = ConvertFault & { path: ConvertErrorPath }
+
 export type Result<T> = { error: ConvertError; ok: false } | { ok: true; value: T }
 
 export function failure<T>(code: ConvertErrorCode, message: string, path: ConvertErrorPath): Result<T> {

todo.md

@@ -268,7 +268,7 @@ detail is settled at its own milestone.
         break of either kind inside one reads as a space. And a destination or title whose entity
         reference decodes to a control character — `[a](/x
y)` — joins 3k's exception list
         beside the two above: the reader takes cmark's reading, the emitter has no spelling for it.
-  - [ ] **3f — The directive grammar.** The three forms — inline `:name[content]{attrs}`,
+  - [x] **3f — The directive grammar.** The three forms — inline `:name[content]{attrs}`,
         container `:::name arg {attrs}`, leaf `::name arg {attrs}` — the attribute grammar with
         its quoting and escapes, the fence-length and nesting rules, and the malformed list
         `spec/flavour.md` spells, each a named error. `corpus.test.ts`'s `fenceNestingFault` stays a
@@ -278,6 +278,15 @@ detail is settled at its own milestone.
         `|` inside `{attrs}` breaks the directive and is a named error, the author writing the
         `\u0060` the emitter writes. One precedence covers both directions, and CommonMark's own
         ordering stays untouched.
+        **Settled** (the maintainer, 2026-09-01): a directive whose name reads back to no node
+        takes its own code, `unknown-directive-name` — a well-formed spelling the vocabulary does
+        not hold is not a malformed one, and §8's "erroring input gaining meaning later is MINOR"
+        is what a consumer switches the two apart for. And input reads canonical spacing only: one
+        space parting the name, the argument, `{attrs}` and each attribute pair, no padding inside
+        the braces, trailing whitespace on a directive block line tolerated — §8 makes loosening a
+        MINOR, so strict is the reversible direction. `directive-attributes.ts` becomes
+        `directive-syntax.ts` with the readers in it: the whole directive grammar, both
+        directions, beside the escaping regexes and the spellings it must not drift from.
   - [ ] **3g — The node tables read backwards.** `commonmark-subset/` reads back, the first
         directory to. A parsed directive becomes its node: the name to the type and an unknown one
         to a named error, the arg to the attribute it names, each value to the type its section