diff --git a/AGENTS.md b/AGENTS.md
index b55b6f1..f934f73 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -137,7 +137,11 @@ live Atlassian APIs; property-generated ADF trees; the CommonMark spec suite aga
 - No casts: `as`, `as unknown as`, non-null `!`. A boundary owes a type guard validating the
   fields it claims (`isAdfDocument`); past it everything is typed. Make invalid states
   unrepresentable.
-- Explicit over implicit; descriptive names; no catch-all files (`utils`, `helpers`, `misc`).
+- The attribute vocabulary is ADF's: `adf/` walks it and narrows each value to its kind, and a
+  format spells the narrowed value. A spelling that re-checks the type is the check's second copy.
+- Explicit over implicit; descriptive names; no catch-all files (`utils`, `helpers`, `misc`); a
+  file does not repeat its directory in its name — `adf/document.ts`, never
+  `adf/adf-document.ts`.
 - Reuse before adding; the smallest sufficient diff is the benchmark; no speculative generality —
   a second consumer, or it goes.
 
diff --git a/src/adf/attribute-vocabulary.ts b/src/adf/attribute-vocabulary.ts
new file mode 100644
index 0000000..7e30d80
--- /dev/null
+++ b/src/adf/attribute-vocabulary.ts
@@ -0,0 +1,32 @@
+import type { AdfAttributes } from './document.ts'
+import type { JsonValue } from '../json-value.ts'
+
+export type AttributeKind = 'boolean' | 'json' | 'number' | 'string'
+
+export type AttributeVocabulary = Readonly<Record<string, AttributeKind>>
+
+export type VocabularyPair =
+  | { key: string; kind: 'boolean'; value: boolean }
+  | { key: string; kind: 'json'; value: JsonValue }
+  | { key: string; kind: 'number'; value: number }
+  | { key: string; kind: 'string'; value: string }
+
+export function vocabularyPairs(attrs: AdfAttributes, vocabulary: AttributeVocabulary, spelledElsewhere: readonly string[]): VocabularyPair[] | undefined {
+  const pairs: VocabularyPair[] = []
+  for (const [key, value] of Object.entries(attrs)) {
+    if (spelledElsewhere.includes(key)) continue
+    const kind = Object.hasOwn(vocabulary, key) ? vocabulary[key] : undefined
+    if (kind === undefined) return undefined
+    const pair = vocabularyPair(key, value, kind)
+    if (pair === undefined) return undefined
+    pairs.push(pair)
+  }
+  return pairs
+}
+
+function vocabularyPair(key: string, value: JsonValue, kind: AttributeKind): VocabularyPair | undefined {
+  if (kind === 'boolean') return typeof value === 'boolean' ? { key, kind, value } : undefined
+  if (kind === 'number') return typeof value === 'number' ? { key, kind, value } : undefined
+  if (kind === 'string') return typeof value === 'string' ? { key, kind, value } : undefined
+  return { key, kind, value }
+}
diff --git a/src/block-directives.ts b/src/adf/block-directives.ts
similarity index 71%
rename from src/block-directives.ts
rename to src/adf/block-directives.ts
index 817689e..04912a2 100644
--- a/src/block-directives.ts
+++ b/src/adf/block-directives.ts
@@ -1,6 +1,4 @@
-import type { AdfMark, AdfNode, AttributeVocabulary } from './adf-document.ts'
-import type { JsonValue } from './json-value.ts'
-import { isBareToken, spellAttributes, spellJsonAttribute, vocabularyPairs } from './directive-attributes.ts'
+import type { AttributeVocabulary } from './attribute-vocabulary.ts'
 
 export type BlockDirective = {
   argument?: string
@@ -89,29 +87,3 @@ const blockDirectives: Readonly<Record<string, BlockDirective>> = {
 export function blockDirective(type: string): BlockDirective | undefined {
   return Object.hasOwn(blockDirectives, type) ? blockDirectives[type] : undefined
 }
-
-export function spellDirectiveHeader(node: AdfNode, directive: BlockDirective, spelledByBody: readonly string[] = []): string | undefined {
-  const argument = spellArgument(node, directive)
-  if (argument === undefined) return undefined
-  const spelled = directive.argument === undefined ? spelledByBody : [directive.argument, ...spelledByBody]
-  const pairs = vocabularyPairs(node.attrs ?? {}, directive.attributes, spelled)
-  if (pairs === undefined) return undefined
-  const marks = node.marks ?? []
-  if (marks.length > 0) pairs.push(['marks', spellJsonAttribute(markValues(marks))])
-  const attributes = spellAttributes(pairs)
-  return `${node.type}${argument}${attributes === '' ? '' : ` ${attributes}`}`
-}
-
-function spellArgument(node: AdfNode, directive: BlockDirective): string | undefined {
-  const value = directive.argument === undefined ? undefined : node.attrs?.[directive.argument]
-  if (value === undefined) return ''
-  if (typeof value !== 'string' || !isBareToken(value)) return undefined
-  return ` ${value}`
-}
-
-function markValues(marks: readonly AdfMark[]): JsonValue {
-  return marks.map((mark) => {
-    const attrs = mark.attrs ?? {}
-    return Object.keys(attrs).length === 0 ? { type: mark.type } : { attrs, type: mark.type }
-  })
-}
diff --git a/src/adf-document.test.ts b/src/adf/document.test.ts
similarity index 97%
rename from src/adf-document.test.ts
rename to src/adf/document.test.ts
index 1c5eaba..0d1cb91 100644
--- a/src/adf-document.test.ts
+++ b/src/adf/document.test.ts
@@ -1,7 +1,7 @@
 import assert from 'node:assert/strict'
 import test from 'node:test'
 
-import { isAdfDocument } from './adf-document.ts'
+import { isAdfDocument } from './document.ts'
 
 test('accepts an editor-normal document', () => {
   assert.equal(isAdfDocument({ content: [{ content: [{ text: 'x', type: 'text' }], type: 'paragraph' }], type: 'doc', version: 1 }), true)
diff --git a/src/adf-document.ts b/src/adf/document.ts
similarity index 92%
rename from src/adf-document.ts
rename to src/adf/document.ts
index f85ac28..7502f23 100644
--- a/src/adf-document.ts
+++ b/src/adf/document.ts
@@ -1,11 +1,7 @@
-import { isJsonValue, type JsonValue } from './json-value.ts'
+import { isJsonValue, type JsonValue } from '../json-value.ts'
 
 export type AdfAttributes = { [key: string]: JsonValue }
 
-export type AttributeKind = 'boolean' | 'json' | 'number' | 'string'
-
-export type AttributeVocabulary = Readonly<Record<string, AttributeKind>>
-
 export type AdfMark = {
   attrs?: AdfAttributes
   type: string
diff --git a/src/adf/inline-directives.ts b/src/adf/inline-directives.ts
new file mode 100644
index 0000000..73d5e08
--- /dev/null
+++ b/src/adf/inline-directives.ts
@@ -0,0 +1,32 @@
+import type { AttributeVocabulary } from './attribute-vocabulary.ts'
+
+export type InlineDirective = {
+  attributes: AttributeVocabulary
+  slot?: string
+}
+
+const inlineDirectives: Readonly<Record<string, InlineDirective>> = {
+  date: { attributes: { localId: 'string', timestamp: 'string' } },
+  emoji: { attributes: { id: 'string', localId: 'string', shortName: 'string' }, slot: 'text' },
+  hardBreak: { attributes: { localId: 'string', text: 'string' } },
+  inlineCard: { attributes: { data: 'json', localId: 'string', url: 'string' } },
+  mediaInline: {
+    attributes: {
+      alt: 'string',
+      collection: 'string',
+      data: 'json',
+      height: 'number',
+      id: 'string',
+      localId: 'string',
+      occurrenceKey: 'string',
+      type: 'string',
+      width: 'number',
+    },
+  },
+  mention: { attributes: { accessLevel: 'string', id: 'string', localId: 'string', userType: 'string' }, slot: 'text' },
+  status: { attributes: { color: 'string', localId: 'string', style: 'string' }, slot: 'text' },
+}
+
+export function inlineDirective(type: string): InlineDirective | undefined {
+  return Object.hasOwn(inlineDirectives, type) ? inlineDirectives[type] : undefined
+}
diff --git a/src/adf/mark-attributes.ts b/src/adf/mark-attributes.ts
new file mode 100644
index 0000000..7ae22eb
--- /dev/null
+++ b/src/adf/mark-attributes.ts
@@ -0,0 +1,19 @@
+import type { AttributeVocabulary } from './attribute-vocabulary.ts'
+
+export const markAttributes = {
+  border: { color: 'string', size: 'number' },
+  code: {},
+  em: {},
+  link: { href: 'string', title: 'string' },
+  strike: {},
+  strong: {},
+  subsup: { type: 'string' },
+  textColor: { color: 'string' },
+  underline: {},
+} satisfies Readonly<Record<string, AttributeVocabulary>>
+
+export type MarkType = keyof typeof markAttributes
+
+export function isMarkType(type: string): type is MarkType {
+  return Object.hasOwn(markAttributes, type)
+}
diff --git a/src/corpus.test.ts b/src/corpus.test.ts
index 64f4251..a3cafbe 100644
--- a/src/corpus.test.ts
+++ b/src/corpus.test.ts
@@ -4,8 +4,8 @@ import { dirname, join } from 'node:path'
 import test from 'node:test'
 import { fileURLToPath } from 'node:url'
 
-import { adfToMarkdown } from './adf-to-markdown.ts'
-import { isAdfDocument } from './adf-document.ts'
+import { adfToMarkdown } from './markdown/emit/adf-to-markdown.ts'
+import { isAdfDocument } from './adf/document.ts'
 import { isJsonValue } from './json-value.ts'
 import { serializeCanonicalJson } from './canonical-json.ts'
 
diff --git a/src/directive-attributes.ts b/src/directive-attributes.ts
deleted file mode 100644
index b93492d..0000000
--- a/src/directive-attributes.ts
+++ /dev/null
@@ -1,50 +0,0 @@
-import type { AdfAttributes, AttributeKind, AttributeVocabulary } from './adf-document.ts'
-import type { JsonValue } from './json-value.ts'
-import { serializeCanonicalJson } from './canonical-json.ts'
-
-const bareToken = /^[A-Za-z0-9_-]+$/
-
-// spec/flavour.md, Attributes.
-const quotedEscapes = /[&<`|]/g
-
-export function isBareToken(text: string): boolean {
-  return bareToken.test(text)
-}
-
-export function vocabularyPairs(attrs: AdfAttributes, vocabulary: AttributeVocabulary, spelledElsewhere: readonly string[]): [string, string][] | undefined {
-  const pairs: [string, string][] = []
-  for (const [key, value] of Object.entries(attrs)) {
-    if (spelledElsewhere.includes(key)) continue
-    const kind = Object.hasOwn(vocabulary, key) ? vocabulary[key] : undefined
-    if (kind === undefined) return undefined
-    const spelled = spellAttributeValue(value, kind)
-    if (spelled === undefined) return undefined
-    pairs.push([key, spelled])
-  }
-  return pairs
-}
-
-export function spellAttributes(pairs: readonly (readonly [string, string])[]): string {
-  if (pairs.length === 0) return ''
-  const spelled = [...pairs].sort(([left], [right]) => (left < right ? -1 : 1)).map(([key, value]) => `${key}=${value}`)
-  return `{${spelled.join(' ')}}`
-}
-
-export function spellAttributeValue(value: JsonValue, kind: AttributeKind): string | undefined {
-  if (kind === 'json') return spellJsonAttribute(value)
-  if (kind === 'boolean') return typeof value === 'boolean' ? `${value}` : undefined
-  if (kind === 'number') return typeof value === 'number' ? spellStringAttribute(JSON.stringify(value)) : undefined
-  return typeof value === 'string' ? spellStringAttribute(value) : undefined
-}
-
-export function spellJsonAttribute(value: JsonValue): string {
-  return quote(serializeCanonicalJson(value, 'compact'))
-}
-
-export function spellStringAttribute(text: string): string {
-  return isBareToken(text) ? text : quote(text)
-}
-
-function quote(text: string): string {
-  return JSON.stringify(text).replace(quotedEscapes, (character) => `\\u${character.charCodeAt(0).toString(16).padStart(4, '0')}`)
-}
diff --git a/src/index.ts b/src/index.ts
index 6afbe03..056730f 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,5 +1,5 @@
-export type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from './adf-document.ts'
+export type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from './adf/document.ts'
 export type { ConvertError, ConvertErrorCode, Result } from './result.ts'
 export type { JsonValue } from './json-value.ts'
-export { adfToMarkdown } from './adf-to-markdown.ts'
-export { isAdfDocument } from './adf-document.ts'
+export { adfToMarkdown } from './markdown/emit/adf-to-markdown.ts'
+export { isAdfDocument } from './adf/document.ts'
diff --git a/src/inline-directives.ts b/src/inline-directives.ts
deleted file mode 100644
index eaad116..0000000
--- a/src/inline-directives.ts
+++ /dev/null
@@ -1,63 +0,0 @@
-import type { AdfMark, AdfNode, AttributeVocabulary } from './adf-document.ts'
-import { spellAttributes, vocabularyPairs } from './directive-attributes.ts'
-
-export type InlineDirective = {
-  attributes: AttributeVocabulary
-  slot?: string
-}
-
-export type MarkSpelling =
-  | { attributes: AttributeVocabulary; kind: 'code' | 'directive' | 'link'; spelling?: undefined }
-  | { attributes: AttributeVocabulary; kind: 'emphasis'; spelling: string }
-
-const inlineDirectives: Readonly<Record<string, InlineDirective>> = {
-  date: { attributes: { localId: 'string', timestamp: 'string' } },
-  emoji: { attributes: { id: 'string', localId: 'string', shortName: 'string' }, slot: 'text' },
-  hardBreak: { attributes: { localId: 'string', text: 'string' } },
-  inlineCard: { attributes: { data: 'json', localId: 'string', url: 'string' } },
-  mediaInline: {
-    attributes: {
-      alt: 'string',
-      collection: 'string',
-      data: 'json',
-      height: 'number',
-      id: 'string',
-      localId: 'string',
-      occurrenceKey: 'string',
-      type: 'string',
-      width: 'number',
-    },
-  },
-  mention: { attributes: { accessLevel: 'string', id: 'string', localId: 'string', userType: 'string' }, slot: 'text' },
-  status: { attributes: { color: 'string', localId: 'string', style: 'string' }, slot: 'text' },
-}
-
-const markSpellings: Readonly<Record<string, MarkSpelling>> = {
-  border: { attributes: { color: 'string', size: 'number' }, kind: 'directive' },
-  code: { attributes: {}, kind: 'code' },
-  em: { attributes: {}, kind: 'emphasis', spelling: '_' },
-  link: { attributes: { href: 'string', title: 'string' }, kind: 'link' },
-  strike: { attributes: {}, kind: 'emphasis', spelling: '~~' },
-  strong: { attributes: {}, kind: 'emphasis', spelling: '**' },
-  subsup: { attributes: { type: 'string' }, kind: 'directive' },
-  textColor: { attributes: { color: 'string' }, kind: 'directive' },
-  underline: { attributes: {}, kind: 'directive' },
-}
-
-export function inlineDirective(type: string): InlineDirective | undefined {
-  return Object.hasOwn(inlineDirectives, type) ? inlineDirectives[type] : undefined
-}
-
-export function markSpelling(type: string): MarkSpelling | undefined {
-  return Object.hasOwn(markSpellings, type) ? markSpellings[type] : undefined
-}
-
-export function spellInlineNodeAttributes(node: AdfNode, directive: InlineDirective): string | undefined {
-  const pairs = vocabularyPairs(node.attrs ?? {}, directive.attributes, directive.slot === undefined ? [] : [directive.slot])
-  return pairs === undefined ? undefined : spellAttributes(pairs)
-}
-
-export function spellMarkAttributes(mark: AdfMark, vocabulary: AttributeVocabulary): string | undefined {
-  const pairs = vocabularyPairs(mark.attrs ?? {}, vocabulary, [])
-  return pairs === undefined ? undefined : spellAttributes(pairs)
-}
diff --git a/src/backtick-runs.ts b/src/markdown/backtick-runs.ts
similarity index 100%
rename from src/backtick-runs.ts
rename to src/markdown/backtick-runs.ts
diff --git a/src/markdown/block-directive-spelling.ts b/src/markdown/block-directive-spelling.ts
new file mode 100644
index 0000000..446486d
--- /dev/null
+++ b/src/markdown/block-directive-spelling.ts
@@ -0,0 +1,32 @@
+import type { AdfMark, AdfNode } from '../adf/document.ts'
+import type { BlockDirective } from '../adf/block-directives.ts'
+import type { JsonValue } from '../json-value.ts'
+import { isBareToken, spellAttributes, spellJsonAttribute, spellVocabulary } from './directive-attributes.ts'
+import { vocabularyPairs } from '../adf/attribute-vocabulary.ts'
+
+export function spellDirectiveHeader(node: AdfNode, directive: BlockDirective, spelledByBody: readonly string[] = []): string | undefined {
+  const argument = spellArgument(node, directive)
+  if (argument === undefined) return undefined
+  const spelled = directive.argument === undefined ? spelledByBody : [directive.argument, ...spelledByBody]
+  const pairs = vocabularyPairs(node.attrs ?? {}, directive.attributes, spelled)
+  if (pairs === undefined) return undefined
+  const spelledPairs = spellVocabulary(pairs)
+  const marks = node.marks ?? []
+  if (marks.length > 0) spelledPairs.push(['marks', spellJsonAttribute(markValues(marks))])
+  const attributes = spellAttributes(spelledPairs)
+  return `${node.type}${argument}${attributes === '' ? '' : ` ${attributes}`}`
+}
+
+function spellArgument(node: AdfNode, directive: BlockDirective): string | undefined {
+  const value = directive.argument === undefined ? undefined : node.attrs?.[directive.argument]
+  if (value === undefined) return ''
+  if (typeof value !== 'string' || !isBareToken(value)) return undefined
+  return ` ${value}`
+}
+
+function markValues(marks: readonly AdfMark[]): JsonValue {
+  return marks.map((mark) => {
+    const attrs = mark.attrs ?? {}
+    return Object.keys(attrs).length === 0 ? { type: mark.type } : { attrs, type: mark.type }
+  })
+}
diff --git a/src/commonmark-grammar.ts b/src/markdown/commonmark-grammar.ts
similarity index 100%
rename from src/commonmark-grammar.ts
rename to src/markdown/commonmark-grammar.ts
diff --git a/src/markdown/destination-spelling.ts b/src/markdown/destination-spelling.ts
new file mode 100644
index 0000000..619f3ad
--- /dev/null
+++ b/src/markdown/destination-spelling.ts
@@ -0,0 +1,37 @@
+import { failure, success, type ConvertErrorPath, type Result } from '../result.ts'
+import { holdsControlCharacter, holdsEntityReference } from './commonmark-grammar.ts'
+
+export function spellDestination(href: string, path: ConvertErrorPath): Result<string> {
+  if (holdsControlCharacter(href)) return failure('unspellable-link-destination', 'a link destination holds a control character', path)
+  if (href.includes('\\')) return failure('unspellable-link-destination', 'no canonical escape spells a backslash in a link destination', path)
+  if (holdsEntityReference(href)) {
+    return failure('unspellable-link-destination', 'a link destination shaped like an entity reference decodes on the way back', path)
+  }
+  if (href.includes(' ')) {
+    if (/[<>]/.test(href)) {
+      return failure('unspellable-link-destination', 'no canonical escape spells an angle bracket beside a space in a link destination', path)
+    }
+    return success(`<${href}>`)
+  }
+  if (href.startsWith('<')) return failure('unspellable-link-destination', 'a bare link destination cannot begin with an angle bracket', path)
+  if (!balanced(href)) return failure('unspellable-link-destination', 'no canonical escape spells an unbalanced parenthesis in a link destination', path)
+  return success(href)
+}
+
+export function spellTitle(title: string, path: ConvertErrorPath): Result<string> {
+  if (/["\n\r\\]/.test(title)) {
+    return failure('unspellable-link-title', 'no canonical escape spells a quote, backslash or newline in a link title', path)
+  }
+  if (holdsEntityReference(title)) return failure('unspellable-link-title', 'a link title shaped like an entity reference decodes on the way back', path)
+  return success(` "${title}"`)
+}
+
+function balanced(href: string): boolean {
+  let depth = 0
+  for (const character of href) {
+    if (character === '(') depth += 1
+    if (character === ')') depth -= 1
+    if (depth < 0) return false
+  }
+  return depth === 0
+}
diff --git a/src/markdown/directive-attributes.ts b/src/markdown/directive-attributes.ts
new file mode 100644
index 0000000..5a27544
--- /dev/null
+++ b/src/markdown/directive-attributes.ts
@@ -0,0 +1,41 @@
+import type { JsonValue } from '../json-value.ts'
+import type { VocabularyPair } from '../adf/attribute-vocabulary.ts'
+import { serializeCanonicalJson } from '../canonical-json.ts'
+
+const bareToken = /^[A-Za-z0-9_-]+$/
+
+// spec/flavour.md, Attributes.
+const quotedEscapes = /[&<`|]/g
+
+export function isBareToken(text: string): boolean {
+  return bareToken.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')}`)
+}
diff --git a/src/adf-to-markdown.test.ts b/src/markdown/emit/adf-to-markdown.test.ts
similarity index 99%
rename from src/adf-to-markdown.test.ts
rename to src/markdown/emit/adf-to-markdown.test.ts
index 6774b34..398714b 100644
--- a/src/adf-to-markdown.test.ts
+++ b/src/markdown/emit/adf-to-markdown.test.ts
@@ -1,9 +1,9 @@
 import assert from 'node:assert/strict'
 import test from 'node:test'
 
-import type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from './adf-document.ts'
-import type { Result } from './result.ts'
-import { adfToMarkdown } from './index.ts'
+import type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from '../../adf/document.ts'
+import type { Result } from '../../result.ts'
+import { adfToMarkdown } from '../../index.ts'
 
 function document(...content: AdfNode[]): AdfDocument {
   return { content, type: 'doc', version: 1 }
diff --git a/src/adf-to-markdown.ts b/src/markdown/emit/adf-to-markdown.ts
similarity index 94%
rename from src/adf-to-markdown.ts
rename to src/markdown/emit/adf-to-markdown.ts
index 64a89a0..c673dbb 100644
--- a/src/adf-to-markdown.ts
+++ b/src/markdown/emit/adf-to-markdown.ts
@@ -1,16 +1,17 @@
-import type { AdfDocument, AdfNode } from './adf-document.ts'
-import type { BlockDirective } from './block-directives.ts'
-import type { JsonValue } from './json-value.ts'
-import { blockDirective, spellDirectiveHeader } from './block-directives.ts'
-import { tryImage } from './markdown-image.ts'
-import { emitInlineLine } from './markdown-inline.ts'
-import { tryPipeTable } from './markdown-pipe-table.ts'
-import { carriedBlock, carryName } from './opaque-carry.ts'
-import { failure, success, type ConvertErrorPath, type Result } from './result.ts'
-import { holdsControlCharacter, holdsEntityReference, holdsNullCharacter, isThematicBreak } from './commonmark-grammar.ts'
-import { carriesOnly, isAdfDocument } from './adf-document.ts'
-import { largestNesting } from './nesting.ts'
-import { fencedCodeBlock } from './backtick-runs.ts'
+import type { AdfDocument, AdfNode } from '../../adf/document.ts'
+import type { BlockDirective } from '../../adf/block-directives.ts'
+import type { JsonValue } from '../../json-value.ts'
+import { blockDirective } from '../../adf/block-directives.ts'
+import { carriedBlock, carryName } from '../opaque-carry.ts'
+import { carriesOnly, isAdfDocument } from '../../adf/document.ts'
+import { emitInlineLine } from './inline-line.ts'
+import { failure, success, type ConvertErrorPath, type Result } from '../../result.ts'
+import { fencedCodeBlock } from '../backtick-runs.ts'
+import { holdsControlCharacter, holdsEntityReference, holdsNullCharacter, isThematicBreak } from '../commonmark-grammar.ts'
+import { largestNesting } from '../../nesting.ts'
+import { spellDirectiveHeader } from '../block-directive-spelling.ts'
+import { tryImage } from './image.ts'
+import { tryPipeTable } from './pipe-table.ts'
 
 type BlockContainer = 'directive' | 'document' | 'list-item'
 type BlockSpelling = 'commonmark' | 'directive'
diff --git a/src/markdown-image.ts b/src/markdown/emit/image.ts
similarity index 79%
rename from src/markdown-image.ts
rename to src/markdown/emit/image.ts
index 1eaf509..f44a880 100644
--- a/src/markdown-image.ts
+++ b/src/markdown/emit/image.ts
@@ -1,8 +1,8 @@
-import type { AdfNode } from './adf-document.ts'
-import { carriesOnly } from './adf-document.ts'
-import type { ConvertErrorPath } from './result.ts'
-import { serializeCanonicalJson } from './canonical-json.ts'
-import { tryImageLine } from './markdown-inline.ts'
+import type { AdfNode } from '../../adf/document.ts'
+import { carriesOnly } from '../../adf/document.ts'
+import type { ConvertErrorPath } from '../../result.ts'
+import { serializeCanonicalJson } from '../../canonical-json.ts'
+import { tryImageLine } from './inline-line.ts'
 
 const centeredMediaSingle = '{"layout":"center"}'
 const imageAttributes = ['alt', 'type', 'url']
diff --git a/src/markdown-inline.ts b/src/markdown/emit/inline-line.ts
similarity index 86%
rename from src/markdown-inline.ts
rename to src/markdown/emit/inline-line.ts
index b1bdea8..76edfba 100644
--- a/src/markdown-inline.ts
+++ b/src/markdown/emit/inline-line.ts
@@ -1,14 +1,17 @@
-import type { AdfMark, AdfNode } from './adf-document.ts'
-import type { InlineDirective } from './inline-directives.ts'
-import { assembleInlineLine, type InlineEscaping, type InlineSegment, type LineContainer, type NodeRange } from './markdown-escaping.ts'
-import { inlineDirective, markSpelling, spellInlineNodeAttributes, spellMarkAttributes } from './inline-directives.ts'
-import { largestNesting } from './nesting.ts'
-import { claimsLine, holdsControlCharacter, holdsEntityReference, holdsNullCharacter, isAutolink } from './commonmark-grammar.ts'
-import { carriedInline } from './opaque-carry.ts'
-import { failure, success, type ConvertErrorPath, type Result } from './result.ts'
-import { longestBacktickRun } from './backtick-runs.ts'
-import { serializeCanonicalJson } from './canonical-json.ts'
-import { spellAttributes, spellStringAttribute } from './directive-attributes.ts'
+import type { AdfMark, AdfNode } from '../../adf/document.ts'
+import type { InlineDirective } from '../../adf/inline-directives.ts'
+import { assembleInlineLine, type InlineEscaping, type InlineSegment, type LineContainer, type NodeRange } from './line-escaping.ts'
+import { carriedInline } from '../opaque-carry.ts'
+import { claimsLine, holdsEntityReference, holdsNullCharacter, isAutolink } from '../commonmark-grammar.ts'
+import { failure, success, type ConvertErrorPath, type Result } from '../../result.ts'
+import { inlineDirective } from '../../adf/inline-directives.ts'
+import { largestNesting } from '../../nesting.ts'
+import { longestBacktickRun } from '../backtick-runs.ts'
+import { markSpelling, spellMarkAttributes } from '../mark-spellings.ts'
+import { serializeCanonicalJson } from '../../canonical-json.ts'
+import { spellAttributes, spellStringAttribute } from '../directive-attributes.ts'
+import { spellDestination, spellTitle } from '../destination-spelling.ts'
+import { spellInlineNodeAttributes } from '../inline-directive-spelling.ts'
 
 type EmittedLine = { line: string; segments: InlineSegment[] }
 
@@ -293,41 +296,6 @@ function emitLink(nodes: readonly AdfNode[], mark: AdfMark, depth: number, range
   return success({ segments: [syntax('['), ...inner.value.segments, syntax(`](${destination.value}${spelledTitle.value})`)] })
 }
 
-function spellDestination(href: string, path: ConvertErrorPath): Result<string> {
-  if (holdsControlCharacter(href)) return failure('unspellable-link-destination', 'a link destination holds a control character', path)
-  if (href.includes('\\')) return failure('unspellable-link-destination', 'no canonical escape spells a backslash in a link destination', path)
-  if (holdsEntityReference(href)) {
-    return failure('unspellable-link-destination', 'a link destination shaped like an entity reference decodes on the way back', path)
-  }
-  if (href.includes(' ')) {
-    if (/[<>]/.test(href)) {
-      return failure('unspellable-link-destination', 'no canonical escape spells an angle bracket beside a space in a link destination', path)
-    }
-    return success(`<${href}>`)
-  }
-  if (href.startsWith('<')) return failure('unspellable-link-destination', 'a bare link destination cannot begin with an angle bracket', path)
-  if (!balanced(href)) return failure('unspellable-link-destination', 'no canonical escape spells an unbalanced parenthesis in a link destination', path)
-  return success(href)
-}
-
-function spellTitle(title: string, path: ConvertErrorPath): Result<string> {
-  if (/["\n\r\\]/.test(title)) {
-    return failure('unspellable-link-title', 'no canonical escape spells a quote, backslash or newline in a link title', path)
-  }
-  if (holdsEntityReference(title)) return failure('unspellable-link-title', 'a link title shaped like an entity reference decodes on the way back', path)
-  return success(` "${title}"`)
-}
-
-function balanced(href: string): boolean {
-  let depth = 0
-  for (const character of href) {
-    if (character === '(') depth += 1
-    if (character === ')') depth -= 1
-    if (depth < 0) return false
-  }
-  return depth === 0
-}
-
 function sameMark(candidate: AdfMark, mark: AdfMark): boolean {
   if (candidate.type !== mark.type) return false
   return serializeCanonicalJson(candidate.attrs ?? {}, 'compact') === serializeCanonicalJson(mark.attrs ?? {}, 'compact')
diff --git a/src/markdown-escaping.ts b/src/markdown/emit/line-escaping.ts
similarity index 99%
rename from src/markdown-escaping.ts
rename to src/markdown/emit/line-escaping.ts
index 40ad3ec..f84fde7 100644
--- a/src/markdown-escaping.ts
+++ b/src/markdown/emit/line-escaping.ts
@@ -1,5 +1,5 @@
-import { escapesLineClaim, opensBracketedAutolink, startsEntityReference, type LinePosition } from './commonmark-grammar.ts'
-import { delimiterFlags, isWordCharacter, matchEmphasis } from './emphasis-matching.ts'
+import { escapesLineClaim, opensBracketedAutolink, startsEntityReference, type LinePosition } from '../commonmark-grammar.ts'
+import { delimiterFlags, isWordCharacter, matchEmphasis } from '../emphasis-matching.ts'
 
 export type EmphasisRole = 'close' | 'open'
 
diff --git a/src/markdown-pipe-table.ts b/src/markdown/emit/pipe-table.ts
similarity index 89%
rename from src/markdown-pipe-table.ts
rename to src/markdown/emit/pipe-table.ts
index 8756a69..6439b44 100644
--- a/src/markdown-pipe-table.ts
+++ b/src/markdown/emit/pipe-table.ts
@@ -1,7 +1,7 @@
-import type { AdfNode } from './adf-document.ts'
-import { carriesOnly } from './adf-document.ts'
-import { tryPipeCell } from './markdown-inline.ts'
-import type { ConvertErrorPath } from './result.ts'
+import type { AdfNode } from '../../adf/document.ts'
+import { carriesOnly } from '../../adf/document.ts'
+import { tryPipeCell } from './inline-line.ts'
+import type { ConvertErrorPath } from '../../result.ts'
 
 export function tryPipeTable(node: AdfNode, path: ConvertErrorPath): string | undefined {
   const rows = pipeRows(node)
diff --git a/src/emphasis-matching.ts b/src/markdown/emphasis-matching.ts
similarity index 100%
rename from src/emphasis-matching.ts
rename to src/markdown/emphasis-matching.ts
diff --git a/src/markdown/inline-directive-spelling.ts b/src/markdown/inline-directive-spelling.ts
new file mode 100644
index 0000000..a994d2f
--- /dev/null
+++ b/src/markdown/inline-directive-spelling.ts
@@ -0,0 +1,9 @@
+import type { AdfNode } from '../adf/document.ts'
+import type { InlineDirective } from '../adf/inline-directives.ts'
+import { spellAttributes, spellVocabulary } from './directive-attributes.ts'
+import { vocabularyPairs } from '../adf/attribute-vocabulary.ts'
+
+export function spellInlineNodeAttributes(node: AdfNode, directive: InlineDirective): string | undefined {
+  const pairs = vocabularyPairs(node.attrs ?? {}, directive.attributes, directive.slot === undefined ? [] : [directive.slot])
+  return pairs === undefined ? undefined : spellAttributes(spellVocabulary(pairs))
+}
diff --git a/src/markdown/mark-spellings.ts b/src/markdown/mark-spellings.ts
new file mode 100644
index 0000000..b93f208
--- /dev/null
+++ b/src/markdown/mark-spellings.ts
@@ -0,0 +1,35 @@
+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 { vocabularyPairs } from '../adf/attribute-vocabulary.ts'
+
+type Spelling = { kind: 'code' | 'directive' | 'link'; spelling?: undefined } | { kind: 'emphasis'; spelling: string }
+
+export type MarkSpelling = Spelling & { attributes: AttributeVocabulary }
+
+const markSpellings: Readonly<Record<MarkType, Spelling>> = {
+  border: { kind: 'directive' },
+  code: { kind: 'code' },
+  em: { kind: 'emphasis', spelling: '_' },
+  link: { kind: 'link' },
+  strike: { kind: 'emphasis', spelling: '~~' },
+  strong: { kind: 'emphasis', spelling: '**' },
+  subsup: { kind: 'directive' },
+  textColor: { kind: 'directive' },
+  underline: { kind: 'directive' },
+}
+
+export function markSpelling(type: string): MarkSpelling | undefined {
+  if (!isMarkType(type)) return undefined
+  const spelling = markSpellings[type]
+  const attributes = markAttributes[type]
+  if (spelling.kind === 'emphasis') return { attributes, kind: spelling.kind, spelling: spelling.spelling }
+  return { attributes, kind: spelling.kind }
+}
+
+export function spellMarkAttributes(mark: AdfMark, vocabulary: AttributeVocabulary): string | undefined {
+  const pairs = vocabularyPairs(mark.attrs ?? {}, vocabulary, [])
+  return pairs === undefined ? undefined : spellAttributes(spellVocabulary(pairs))
+}
diff --git a/src/opaque-carry.ts b/src/markdown/opaque-carry.ts
similarity index 78%
rename from src/opaque-carry.ts
rename to src/markdown/opaque-carry.ts
index 2acbd92..1e6ecd1 100644
--- a/src/opaque-carry.ts
+++ b/src/markdown/opaque-carry.ts
@@ -1,10 +1,10 @@
-import type { AdfNode } from './adf-document.ts'
-import type { JsonSpelling } from './canonical-json.ts'
-import { failure, success, type ConvertErrorPath, type Result } from './result.ts'
-import { isJsonValue } from './json-value.ts'
+import type { AdfNode } from '../adf/document.ts'
+import type { JsonSpelling } from '../canonical-json.ts'
+import { failure, success, type ConvertErrorPath, type Result } from '../result.ts'
+import { isJsonValue } from '../json-value.ts'
 import { fencedCodeBlock } from './backtick-runs.ts'
-import { largestNesting } from './nesting.ts'
-import { serializeCanonicalJson } from './canonical-json.ts'
+import { largestNesting } from '../nesting.ts'
+import { serializeCanonicalJson } from '../canonical-json.ts'
 import { spellAttributes, spellStringAttribute } from './directive-attributes.ts'
 
 export const carryName = 'adf'
diff --git a/todo.md b/todo.md
index 4127b79..f457c9c 100644
--- a/todo.md
+++ b/todo.md
@@ -168,7 +168,7 @@ detail is settled at its own milestone.
       unbounded nesting actually arrives, so §11's 500 binds all three of the emitter's guards
       here: block depth at 3c and again at 3f's container fences, inline and mark depth at 3f and
       3i, a carried value's JSON at 3j, where `isJsonValue` already bounds it.
-  - [ ] **3a — The hierarchy.** Mechanical, ahead of the first parser file: `src/adf/` and
+  - [x] **3a — The hierarchy.** Mechanical, ahead of the first parser file: `src/adf/` and
         `src/markdown/` (`html/` arrives with its first file, 6-7), the grammar module shared
         inside `markdown/`, and `emphasis-matching.ts` beside it — the parser reuses it whole,
         `delimiterFlags` and `matchEmphasis` taking CommonMark's own run vocabulary rather than