Convert an existing DOM to Markdown through a small read-only interface. This is an independent implementation with no runtime dependencies, HTML parser, or intermediate DOM. moli-dom::native::NativeDom implements the interface directly.

let root = dom.body_node_id().unwrap_or(dom.document_node_id());
let markdown = moli_html2md::Converter::new(moli_html2md::Options {
    max_depth: 1000,
    default_code_language: Some("text".to_owned()),
    ..Default::default()
})
.convert(&dom, root);

DOM interface

Implement Dom with a copyable node ID and four borrowed queries:

node_kind: document/fragment, lowercase element tag, decoded text, or ignored node.
first_child and next_sibling: ordered traversal of a stable, acyclic tree.
attribute: decoded attribute value, borrowed from the DOM.

The converter does not need parent pointers, mutable access, serialization, or an allocation for each node. The caller chooses the root; its siblings are not visited. Other nodes and their subtrees are ignored. Unknown elements expose their children as ordinary content. Comments and doctypes produce no output.

State machine

A heap task stack tracks node entry, sibling continuation, and element exit. Traversal stores one continuation per level instead of collecting all children.
An inline writer tracks desired and emitted styles, pending whitespace, and block boundaries. It collapses HTML whitespace across node boundaries, keeps Unicode spaces, and coalesces adjacent identical emphasis without changing nodes.
Lists, quotes, and headings have output buffers finalized by exit tasks. Raw code text uses the same iterative traversal with formatting disabled.
List spacing follows block boundaries recorded during conversion. Nested lists keep their own spacing; list items need no preliminary DOM scan.
Ordered lists use start followed by sequential numbers, like Turndown core. reversed and individual li[value] attributes are not represented.
Code fences are chosen after collecting the code text. Language names retain punctuation and Unicode; a name containing backticks uses a tilde fence. Fallback language hints end at the first line ending.

Tables, sections, rows, and cells follow Turndown core's ordinary block behavior: their content is emitted in DOM order, separated by blank lines. Nested tables use the same rule. The converter does not classify layout tables or generate GFM table syntax; headers, roles, borders, and spans do not select another path.

Supported output includes headings, paragraphs, emphasis, strikethrough, links, images, lists, blockquotes, hard breaks, and fenced code. Inline HTML is used when Markdown delimiters cannot express an emphasis boundary. Script/style/head/noscript/template subtrees are omitted.

max_depth counts the supplied root as depth zero; nodes at or beyond the limit are omitted. All traversal paths, including raw code, use this limit.

preformatted_code preserves whitespace inside inline code when enabled. Its default is false, which collapses ordinary HTML whitespace and moves boundary spaces outside code delimiters. Fenced blocks always preserve nonempty code's spaces and blank lines. Empty blocks still separate surrounding text.

This is a structural content dump. It does not evaluate CSS, visibility, layout, or JavaScript, and cannot preserve all HTML presentation (for example, arbitrary ordered-list numbering or table spanning). DOM snapshots used by Moli's optional strip/base/frame transformations remain the responsibility of the caller.

Verification

cargo test -p moli-html2md covers an independent arena DOM, immutability, whitespace, escaping, code, tables, depth limits, and 20,000 nested nodes on a 64 KiB thread stack. The Turndown differential suite pins 147 upstream fixtures and 50 additional cases. It compares rendered meaning, checks DOM immutability, and explicitly asserts 12 documented differences that preserve Moli's handling of literal text, code, emphasis, and list boundaries. Targeted regressions also cover empty elements, links, attributes in headings and tables, code whitespace and language names, list numbering, and loose lists. Emphasis tests cover adjacent links that can use Markdown delimiters and intraword link boundaries that still require inline HTML.

The HTML parser, reference JSON reader, and pulldown-cmark renderer are all test-only dependencies. Tests use checked-in reference outputs and require neither Node nor network access. NativeDom integration and real HTML fixtures are tested in moli-renderer-v8.