adf-codec/spec/flavour.md

The markdown flavour

The grammar of the extended markdown adfToMarkdown emits and markdownToAdf parses. Plain CommonMark is a subset with three carve-outs: literal text that matches directive syntax below or opens a pipe table is claimed by the flavour, and a matched ~~ pair spells strike (escape the :, | or ~ to keep it literal) — and one gap: a CommonMark image fits only as its own title-less paragraph — mid-text and titled images are named errors. The emitted form is contract (AGENTS.md §8). Per-node syntaxes build on this grammar in the sections below.

Canonical form

adfToMarkdown emits exactly one spelling; every CommonMark variant of the same document normalizes to it through the round-trip.

• Emphasis _em_, strong **strong**, strike ~~strike~~; * replaces _ only where _ cannot parse (intra-word). Strike is GFM strikethrough narrowed to exactly two tildes — a single tilde or a run of three or more is literal text — and block structure resolves before inline, so a ~~~ line opens a CommonMark tilde code fence.
• Bullet lists - ; ordered lists incrementing 1. 2. 3., the first number the node's order attribute. Continuation lines align with the first character after the marker (two spaces for - , three for 1. ); blank lines inside an item are empty lines, none between a nested list and a CommonMark block above it — one where the nested list's own marker cannot interrupt a paragraph (any ordered list, or a bullet list whose first item opens with an empty block), which the block above would otherwise swallow. Blank lines between items normalize away; ADF does not record tightness.
• Blockquotes prefix lines with > ; a blank line inside a blockquote is a bare >.
• ATX headings (# … ######); setext input normalizes to ATX.
• Code fences ``` with the node's language as info string, the fence lengthened past any backtick run in the content — the longest run anywhere plus one, at least three, counting mid-line runs no closing fence could match; indented-code input normalizes to fences.
• Code spans: a backtick string one longer than the longest backtick run in the text, the text padded with one space on each side where it begins or ends with a backtick, or begins and ends with a space without being all spaces. The content is literal — inline parsing does not see inside it, directive syntax and ~~ included.
• Thematic break ---.
• Hard break: backslash at end of line (survives editors that trim trailing spaces). Where CommonMark admits no spelling — the end of a block, inside an ATX heading — or where the node carries an attribute, it is the inline directive.
• An empty paragraph — real payloads carry them — is ::paragraph.
• Links [text](url); <…> around a destination containing spaces; title in double quotes. <url> autolink form only when the text equals the destination and the destination is a valid CommonMark autolink (absolute URI).
• Paragraphs on one line — no soft wrapping; a soft line break in input becomes a single space.
• Entity references in input decode to their characters; output backslash-escapes only where text would otherwise parse as syntax, scanning the assembled line rather than each text node: escape the leading delimiter of a construct that would otherwise open, re-scan from there, and repeat. An emphasis delimiter run in text escapes where CommonMark can open or close with it, so *not emphasis* is \*not emphasis\* — no delimiter the emitter did not write reaches the matching below, which is what lets the emitter decide its own pairings.
• Blocks separated by one blank line at document level, inside a blockquote and between CommonMark blocks; two directive blocks inside a container take none. No trailing whitespace outside a code block's content, single trailing newline; a document with no blocks is the empty string.

Directives

One grammar for everything CommonMark lacks. A directive name is [a-z][A-Za-z0-9]* — the ADF node and mark names the sections below spell as directives. Recognition is syntactic and name-set-independent: anything matching the forms below parses as a directive regardless of whether the name is known, and an unknown name is an error result naming it — so output an old emitter escaped stays escaped, and erroring input gaining meaning later is MINOR, never a reparse (§8). The name adf is reserved for the opaque carry, as both directive name and fence info string.

Inline: :name[content]{attrs}, on one line — an inline directive never spans lines. [content] is inline markdown; brackets inside balance as in CommonMark link text, \] for a literal bracket. Whitespace at either edge of [content], space or tab, is part of it and survives inline parsing. Each section below says whether content is required. : opens a directive only when the name is followed immediately by [ or {, and {attrs} must follow ] (or the name) with no gap — anything else (10:30, :smile:, a stray {…} in text) is literal text. An inline directive binds as a unit before bracket matching, the way a code span does: a ] or ( inside its {attrs} is the directive's, never the enclosing content's, and a ( after its closing ] opens no link.

Container block:

:::name arg {attrs}
block content
:::

The fence is three or more colons. arg is one optional bare token whose meaning each node defines (e.g. the panel type). The body is block markdown. The closing fence is a line of at least the opening's length, and a container's fence is longer than every directive fence line 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.

Leaf block: ::name arg {attrs} — a block-position node with no body, arg reading as above.

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 container is open, a named error otherwise. A claimed line also ends a lazy continuation: the blockquote or list item whose paragraph CommonMark would fold it into closes instead.

Attributes: {key=value key2="two words"}. {attrs} is optional in every form, and {} is valid — no attributes. A bare value matches [A-Za-z0-9_-]+; any other value is double-quoted with JSON string escaping (\" \\ \n \t \uXXXX, …) — total over Unicode, and raw newlines never appear inside quotes. A quoted value also escapes `, &, < and | as \u0060, \u0026, \u003c and \u007c; *, _, ~, [, ] and ( resolve after a directive binds and stay raw. The closing } is the first one outside quotes, since a quoted value holds } unescaped. All values are strings at the grammar level; each node's section assigns types. Canonical form orders keys alphabetically, spells values bare wherever allowed, escapes inside quotes in the shortest form each escape has, and omits empty {attrs} except where the { itself claims the directive (:hardBreak{}).

Escaping: the emitter backslash-escapes whatever literal text would otherwise parse as directive syntax — the leading : of a would-be directive, ] inside content, a { right after a directive's closing ], which would otherwise be read as the attributes it has none of; outside code spans and code blocks, a backslash before : in input yields a literal colon.

Malformed directives are error results, named: an unclosed container at end of input, a body fence line of the container's length or longer, a bare colon-run line outside any container or shorter than the fence it would close, an inline [content] or {attrs} left unclosed at end of line, unparseable or duplicate-keyed attrs, invalid JSON in an opaque carry. Never a silent literal-text fallback — a typo that reparses as prose is the silent loss §2 refuses.

The opaque carry (AGENTS.md §3)

A node no section spells where it stands — an unknown type, or a known one whose spelling belongs to the other position — rides as its raw JSON and restores to a deep-equal node. Block and inline positions canonicalize differently, each fitting where it sits:

• Block position: a fenced code block with info string adf, body = the node's JSON — two-space indent, object keys sorted.
• Inline position: :adf{json="…"} — compact serialization (keys sorted, no whitespace), JSON-string-escaped into the attribute.

The info string adf is reserved: a genuine codeBlock whose language is exactly adf takes the attribute the section below keeps for a language no info string holds, so the reservation stays absolute. In block-directive positions (::adf, :::adf) the reserved name is a named error — the carry's block form is the fence.

Raw HTML in input

CommonMark input may contain raw HTML. markdownToAdf routes each construct through the foreign HTML element mapping (AGENTS.md §3; specified with the HTML dialect, todo.md milestone 6) — ADF has no raw-HTML node, so a construct without a mapping, comments and processing instructions included, is an error result naming it. The flavour never emits raw HTML.

Block nodes

The directive name is always the ADF node type. A container's body is the node's content; a leaf has none. Every directive parses in any position — markdownToAdf builds exactly what is written; validity against ADF's content models stays the author's business (AGENTS.md §14).

Each section lists attributes as name (type). A parenthesized value set documents what real payloads hold; the type stays string and any value round-trips verbatim. Values map to attrs by type: strings verbatim, numbers and booleans in canonical JSON spelling — quoted where not bare (width="33.33") — and json values as the inline carry's serialization (compact, keys sorted), quoted. markdownToAdf emits attrs, content and marks keys only when non-empty; editor-normal ADF reads an empty attrs object, marks array or content array as the absent key (AGENTS.md §2) — the grammar's empty-{attrs} omission already collapses the two spellings.

Marks on a block node ride the reserved attribute key marks — the node's marks array as a json value: ::::layoutSection {marks="[{\"attrs\":{\"mode\":\"wide\"},\"type\":\"breakout\"}]"}. A section saying its body is inline takes at most one paragraph, whose inline content becomes the node's content; any other body is a named error, and a node holding no content is the leaf.

A node the sections cannot spell rides the opaque carry: an attrs key its section does not list, a value that is not the section's type, or an arg-slot value that is no bare token. In markdown input the same mismatch is a named error.

The CommonMark blocks

CommonMark spells blockquote, bulletList, codeBlock, heading, listItem, orderedList, paragraph and rule, and keeps that spelling wherever it holds what the node carries. What it cannot — localId (string) on any of them, marks, and the values below — takes the directive form.

• blockquote, bulletList, listItem — containers, block body; no attributes beyond localId.
• codeBlock — container, body one fenced code block whose info string is the language and whose content is the node's. Attributes: hideLineNumbers (boolean), language (string), localId, uniqueId (string), wrap (boolean). A language no info string carries back — empty, the reserved adf, or holding a backtick, a backslash, a control character, edge whitespace or an entity reference — rides the language attribute instead and the fence carries no info string; writing both is a named error.
• heading — container, inline body. Attributes: level (number), localId. level is the # count, so a heading carrying none, or one that is no whole number from 1 to 6, has no CommonMark spelling.
• orderedList — container of listItem, block body. Attributes: localId, order (number). order is the first marker, so a list carrying none, one that is no whole number from 0, or one whose markers would run past 999999999, has no CommonMark spelling.
• paragraph — container, inline body; no attributes beyond localId.
• rule — leaf; no attributes beyond localId.

:::codeBlock {localId=01a03d5c-9b21-73f4-8e6a-0c47b1d9e2f8 wrap=true}
```rust
fn main() {}
```
:::

Panel

Container; the arg is panelType (custom error info note success tip warning). Attributes: localId (string), panelColor (string), panelIcon (string), panelIconId (string), panelIconText (string) — the editor writes the last four for custom panels.

:::panel warning
Check the collation before importing.
:::

Expand

expand and nestedExpand: containers, no arg — same syntax, two node types, the name picks which. Attributes: localId (string), title (string).

:::expand {title="Full build log"}
…
:::

The media family

• media — leaf. Attributes: alt (string), collection (string), height (number), id (string), localId (string), occurrenceKey (string), type (external file link), url (string), width (number). file and link media carry collection + id; external media carry url.
• mediaSingle — container: one ::media, then optionally one :::caption. Attributes: layout (align-end align-start center full-width wide wrap-left wrap-right), localId (string), width (number), widthType (percentage pixel).
• caption — container, inline body. Attributes: localId (string).
• mediaGroup — container of ::media leaves, no attributes.

::::mediaSingle {layout=center width=50}
::media {collection=MediaServicesSample id=4478e39c-cf9b-41d1-ba92-68589487cd75 type=file}
:::caption
The moon, at night.
:::
::::

The CommonMark image. A paragraph whose entire inline content is one image ![alt](url) is a mediaSingle with attrs exactly {"layout":"center"} holding an external media — url from the destination, alt the description's plain-text content when non-empty. adfToMarkdown emits the image form for exactly that shape — those attrs and no others, no marks on either node, no caption, and a media carrying nothing beyond alt, type and url — and only where CommonMark spells the pair: a destination or a description the image form cannot hold, an empty alt included, takes the directive form instead. An image amid other text, or one carrying a title, is a named error: mediaInline carries a media collection + id, never a URL, and no media node carries a title.

Tables

One header row plus plain inline cells is a pipe table; anything richer is the directive form (AGENTS.md §4). Precisely: a table emits as a pipe table exactly when the table, every row and every cell carry no attrs and no marks, the first row is all tableHeader and the rest all tableCell, every row has the header's cell count, and every cell holds exactly one attr-less, mark-less paragraph — an empty cell holds one empty paragraph — with no | anywhere the inline layer spells as syntax: a code span, an autolink, a link destination or title. A | there takes the directive form instead. A pipe table parses back to exactly that shape.

| Part | Qty |
| --- | --- |
| Bolt M8 | 40 |

Claiming at block level, symmetric with directives: a line opening with an unescaped | is claimed and must parse as part of a pipe table, else it is a named error — escape the pipe (\|) to keep it literal text. A pipe table is a header row, a delimiter row whose cells are runs of one or more - (canonical ---), and body rows; rows follow code-fence indentation. Cells split on unescaped | before inline parsing — \| stays in the cell text, and the inline layer's ordinary CommonMark escaping yields the pipe; each cell is the inline content of one paragraph, trimmed; canonical form pads cells with single spaces and ends rows with | (optional in input). Named errors: a delimiter or body row whose cell count differs from the header's, and an alignment colon in the delimiter row — ADF holds no column alignment. In a pipe cell a hard break is :hardBreak{} and a literal | is \|; a | inside a quoted attribute value is already \u007c, so the split never reaches it.

The directive form nests cells as containers of block content inside tableRow containers:

:::::table {isNumberColumnEnabled=true width=760}
::::tableRow
:::tableHeader {colspan=2 colwidth="[340,420]"}
Assembly
:::
::::
::::tableRow
:::tableCell {background="#deebff"}
Bolt M8
:::
:::tableCell {valign=top}
40
:::
::::
:::::

Attributes — table: displayMode (default fixed), isNumberColumnEnabled (boolean), layout (align-end align-start center default full-width wide), localId (string), width (number, pixels). tableRow: localId (string). tableCell and tableHeader: background (string), colspan (number), colwidth (json, one pixel width per spanned column), localId (string), rowspan (number), valign (bottom middle top).

Task and decision lists

• taskList — container of taskItem, blockTaskItem and nested taskList directives. Attributes: localId (string).
• taskItem — container, inline body; the arg is the state (DONE TODO). Attributes: localId (string).
• blockTaskItem — container, block body; arg and attributes as taskItem.
• decisionList — container of decisionItem directives. Attributes: localId (string).
• decisionItem — container, inline body. Attributes: localId (string), state (string — free-form; the editor writes DECIDED).

::::taskList {localId=0198f3a2-7c41-7f2e-9b3a-4d8e2c1a6b90}
:::taskItem DONE {localId=0198f3a2-8d52-70b1-8c4f-5e9f3d2b7ca1}
Write the spec
:::
:::taskItem TODO {localId=0198f3a2-9e63-7d80-a15b-6fa04e3c8db2}
Ship it
:::
::::

Layout

layoutSection — container of layoutColumn containers; attributes: localId (string). layoutColumn — container, block body; attributes: localId (string), valign (bottom middle top), width (number — percent).

::::layoutSection
:::layoutColumn {width=50}
Left.
:::
:::layoutColumn {width=50}
Right.
:::
::::

Extensions

extension — leaf. bodiedExtension — container, block body. multiBodiedExtension — container of extensionFrame containers; extensionFrame — container, block body, no attributes. The other three share: extensionKey (string), extensionType (string), layout (default full-width wide), localId (string), parameters (json), text (string).

::extension {extensionKey=toc extensionType="com.atlassian.confluence.macro.core" parameters="{\"maxLevel\":2}"}

Sync blocks

syncBlock — leaf. bodiedSyncBlock — container, block body. Attributes: localId (string), resourceId (string).

::syncBlock {localId=0198f3a2-af74-7e91-b26c-70b15f4d9ec3 resourceId="ari:cloud:confluence:site/page/123"}

Inline nodes

Attributes and the carry fallback read as in the block sections, the carry in its inline form. Of the nodes below, emoji, mention and status spell their text attribute in the content slot as plain text: [] is the empty string, absent content is the absent attribute, non-empty content parsing to anything but one unmarked text node — adjacent identical-mark text nodes merged first — is a named error, and so is a text key in {attrs}. An enclosing mark spelling does not reach into the slot. The rest take no content, :text included; content on a node that takes none is a named error.

• date — localId (string), timestamp (string, epoch milliseconds).
• emoji — id (string), localId (string), shortName (string, :name:), text (string).
• hardBreak — localId (string), text (string).
• inlineCard — data (json), localId (string), url (string); real payloads carry one or the other.
• mediaInline — alt (string), collection (string), data (json), height (number), id (string), localId (string), occurrenceKey (string), type (file image link), width (number).
• mention — accessLevel (APPLICATION CONTAINER NONE SITE), id (string), localId (string), text (string), userType (APP DEFAULT SPECIAL).
• status — color (blue green neutral purple red yellow), localId (string), style (string), text (string).

:status[In review]{color=yellow} — :mention[@Mikael]{id=01a032c3-7a7c-775f-a730-2d79351338b4}

Shipped :emoji[🎉]{shortName=":tada:"} on :date{timestamp=1756080000000}.

Whitespace CommonMark cannot hold. A newline inside a text node, and a space or tab where CommonMark strips or refuses one — a block's inline content edges, either side of a line break, an em, strong or strike spelling's inner edges, a pipe cell's edges — is spelled :text{text="…"}, the reserved key carrying the node's text, escaped by the attribute grammar and never literal: pipe cells trim and pad. The emitter wraps the whitespace run alone and leaves the rest plain text; markdownToAdf merges adjacent text nodes carrying identical marks (AGENTS.md §2).

:text{text="  "}Two leading spaces held, and one text node split:text{text="\n"}over two lines.

Marks

An inline node's marks ride the spelling wrapped around them, never the block sections' reserved marks key. code, em, link, strike and strong keep their markdown spellings, which hold no attributes beyond link's href and title, and are not directive names: :em[x] is a named error. The other four are inline directives, content required non-empty:

• border — color (string, #rrggbb or #rrggbbaa), size (number, 1–3).
• subsup — type (sub sup).
• textColor — color (string, #rrggbb).
• underline — no attributes.

A spelling adds its mark to every inline node it wraps, and nesting is the marks array in order, outermost first: _:underline[x]_ gives marks [em, underline], :underline[_x_] the reverse. adfToMarkdown nests in the order the array holds rather than sorting it — §2's equality restores the array, not a set — and opens each spelling once over the longest run of adjacent inline nodes carrying an identical mark, attributes included, at that depth. A run breaks at every node the emitter carries, so no emitted carry sits inside a mark spelling.

An inline node whose marks no nesting spells — a mark type not listed here, an attrs key its spelling does not list, a value that is not the spelling's type, an attribute the spelling needs and the mark lacks, an order putting a code span outside another mark, code over anything but a text node or over text holding a newline, or a spelling CommonMark's flanking rules cannot open or close where the run sits (un**-real**istic), or one CommonMark's matching pairs elsewhere — the intra-word * runs together with a neighbouring **, and the multiple-of-3 rule can leave the merged run's pairing to another delimiter — rides the inline carry whole. A value the spelling holds but CommonMark cannot write — a link destination or title — is a named error instead. An opaque carry inside a mark spelling is a named error in input: the carry restores its node exactly, marks included (AGENTS.md §3).

:textColor[**Overdue**]{color="#ae2e24"}, H:subsup[2]{type=sub}O, :underline[signed].

:border[:mediaInline{collection=contentId-98237 id=01a032c3-7a90-70c9-88f6-c60f710eda07}]{color="#091e42" size=2}