Enum Block 

pub enum Block {
    Heading {
        level: u8,
        children: Vec<Inline>,
        id: Option<String>,
    },
    Paragraph(Vec<Inline>),
    Callout {
        kind: CalloutKind,
        fold: Option<Fold>,
        title: Option<String>,
        children: Vec<Block>,
    },
    List {
        ordered: bool,
        start: Option<u64>,
        items: Vec<Vec<Block>>,
        item_source_lines: Vec<Option<usize>>,
    },
    CodeBlock {
        lang: Option<String>,
        value: String,
    },
    Table {
        header: Vec<Vec<Inline>>,
        rows: Vec<Vec<Vec<Inline>>>,
        alignments: Vec<ColumnAlignment>,
        header_source_line: Option<usize>,
        row_source_lines: Vec<Option<usize>>,
    },
    BlockQuote(Vec<Block>),
    Shortcode(Shortcode),
    ThematicBreak,
    Figure {
        image: Inline,
        caption: Option<Vec<Inline>>,
        width: Option<String>,
        align: Option<String>,
        class_names: Vec<String>,
        img_style: Option<String>,
    },
    LinkCard {
        url: Url,
        children: Vec<Block>,
    },
    FootnoteDefinition {
        label: String,
        children: Vec<Block>,
    },
    Other(String),
}

A block-level AST node.

Variants

Heading

# Heading (level 1) through ###### Heading (level 6).

Fields

level: u8

children: Vec<Inline>

id: Option<String>

Heading anchor id (slug). Computed by the parser via crate::heading::anchor::obsidian_heading_anchor.

Paragraph(Vec<Inline>)

A paragraph of inline content.

Callout

> [!type] body — typed callouts. The kind is canonicalized via CalloutKind::from_raw (Obsidian-dialect aliases collapse to the canonical 16-kind set). Foldable callouts (> [!type]+ open by default, > [!type]- closed) carry the Fold state; non-foldable callouts have fold: None.

Phase 4 PR4 extended the shape from kind: String to kind: CalloutKind + added fold: Option<Fold> and title: Option<String>. Title is the optional inline text following the marker (> [!note] My title → title: Some("My title")).

Fields

kind: CalloutKind

fold: Option<Fold>

title: Option<String>

children: Vec<Block>

List

- item / 1. item. Each item is a list of blocks (so list items can carry paragraphs, sub-lists, etc).

item_source_lines is a parallel-to-items vec of 1-based source line numbers, populated by the parser only when crate::ast::ParseConfig::emit_source_lines is true. When tracking is off (production publish builds, the ~40 in-crate parse() callers that use the default config), the vec is empty (vec![]) and the renderer treats every item as None — no data-source-line on the emitted <li>. When tracking is on, length matches items.len() exactly; individual entries may still be None for synthesized items that have no faithful source position (none today, but kept for symmetry with crate::ast::document::BlockMeta::source_line).

Phase 4 source-lines followup (2026-05-28): added because the preview’s scroll-sync (cm-scroll-sync via frontend/bridge/iframe-bridge.ts) interpolates editor positions proportionally between annotated DOM elements. A 30-item list spanning 50 source lines without per-<li> annotations forces interpolation between the outer <ul> and the next top-level block — potentially 100 lines away. Legacy transform_events (commit f91aca8fa, 2026-04-01) emitted on <li> and <tr> for this reason; the typed-AST renderer now matches.

Fields

ordered: bool

start: Option<u64>

Explicit ordered-list start number (pulldown-cmark’s Tag::List(Option<u64>) payload). Some(N) when the source is N. item and the renderer should emit <ol start="N">; None for unordered lists and for ordered lists where N is the implicit default 1. CommonMark only honors the FIRST item’s number as the list start; subsequent numbers are re-derived. Phase 4 followup B (2026-05-28): added because <ol> was previously emitted for any ordered list, silently dropping the explicit start number — 3. foo rendered as <ol><li>foo</li></ol> instead of <ol start="3"><li>foo</li></ol>.

items: Vec<Vec<Block>>

item_source_lines: Vec<Option<usize>>

CodeBlock

A fenced code block.

Fields

lang: Option<String>

value: String

Table

Markdown table.

header_source_line and row_source_lines are populated by the parser only when crate::ast::ParseConfig::emit_source_lines is true. When tracking is off, header_source_line is None and row_source_lines is empty (vec![]); the renderer emits no data-source-line attributes. When tracking is on, row_source_lines.len() == rows.len().

Phase 4 source-lines followup (2026-05-28): see the corresponding doc comment on Block::List for the scroll-sync interpolation rationale.

Fields

header: Vec<Vec<Inline>>

rows: Vec<Vec<Vec<Inline>>>

alignments: Vec<ColumnAlignment>

Per-column GFM alignment, parallel to header. Empty (the common case) means the author declared no alignment on any column. skip_serializing_if keeps previously-serialized ASTs and snapshot fixtures byte-stable when there is no alignment to record.

header_source_line: Option<usize>

row_source_lines: Vec<Option<usize>>

BlockQuote(Vec<Block>)

> blockquote

Shortcode(Shortcode)

A typed shortcode block (:::name ...args\n body :::).

ThematicBreak

<hr> thematic break.

Figure

Image-only paragraph promoted to a typed figure.

Detected by the parser’s Tag::Paragraph arm (Phase 4 PR3, 2026-05-27): a paragraph that contains exactly one Inline::Image modulo whitespace text and line breaks. The renderer emits <figure class="moss-image">…<figcaption>…</figcaption></figure>, wrapping the image hook’s output and appending the caption when present.

image is constrained by the parser to be an Inline::Image; the renderer pattern-matches and falls back gracefully if the variant is anything else.

caption defaults to the image’s alt text at parse time. None means “figure wrap but no <figcaption>” — reserved for the empty-alt case (omit caption when there is nothing to read).

The figure-level display params (width, align, class_names, img_style) are populated only when a figure originates from a parameterized wikilink embed (![[photo.jpg|wide cover]]) — the image-embed synth-collapse routes such embeds through this typed node so width/fit/position/align survive (previously dropped by the markdown round-trip). The CommonMark ![](url) promotion path (try_promote_to_figure) leaves them at their defaults, so its rendered output is byte-identical to before the collapse.

Fields

image: Inline

caption: Option<Vec<Inline>>

width: Option<String>

Canonical width token (body | wide | page | screen) emitted as data-width="…" on the <figure>. None omits the attribute. String (not &'static str) so Block keeps its Deserialize derive; the value is always one of the canonical tokens.

align: Option<String>

Figure-level align class (moss-align-left / moss-align-right), appended to the <figure> class list. None omits it.

class_names: Vec<String>

Extra author-supplied class names appended to the <figure> class list (after moss-image and any align class). Empty = none.

img_style: Option<String>

Inline style= fragment for the INNER <img> (e.g. object-fit:cover;object-position:left from a |cover left embed). None omits it. Distinct from any figure-level attribute: fit/position style belongs on the image element, not the figure.

LinkCard

Compound-link grid cell: the entire cell is a single markdown link [inner](url) whose inner is parsed as block-level content (images, headings, paragraphs, emphasis). The SoCiviC Theatre pattern: [![[poster]] ### Title *date* description](/url).

Phase 4 PR4.5 (2026-05-28): added because CommonMark restricts Inline::Link.children to inline-level content; a markdown link wrapping ### Heading + paragraphs cannot round-trip through pulldown-cmark’s inline parser. The cell-string-level shape ([...](url) with multi-paragraph inner content) is detected by crate::ast::shortcode_extract::parse_grid BEFORE the cell flows through crate::ast::parser::parse; the matched cell yields a single-element vec![Block::LinkCard { url, children }] with the inner markdown parsed into typed blocks.

Render shape (matches today’s render_compound_link_cell byte shape):

• External URL (http(s)://...): <a href=URL class="moss-grid-card link-preview" target="_blank" rel="noopener">children</a>.
• Internal URL: <a href=URL class="moss-grid-card" data-kind="link">children</a>.

Fields

url: Url

children: Vec<Block>

FootnoteDefinition

[^label]: body — a GFM footnote definition, wherever the author wrote it (pulldown-cmark nests one written inside a blockquote or a list item under that container). The renderer hoists it out to the document’s endnote section; see ADR-035.

Fields

label: String

children: Vec<Block>

Other(String)

Raw HTML passthrough: a Tag::HtmlBlock the author wrote, or a payload moss synthesized itself (the shortcode sentinel pass in dispatch_wikilink_embeds). Emitted verbatim. NOT a fallback for unmodeled pulldown constructs — see the module doc.

Trait Implementations

impl Clone for Block

fn clone(&self) -> Block

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Block

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Block

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for Block

impl PartialEq for Block

fn eq(&self, other: &Block) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for Block

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Block