# yjs-html-core
**Internal core** of
[`lexical-yjs-html`](../lexical-html) and
[`prosemirror-yjs-html`](../prosemirror-html): the per-node render rules and
segmented HTML output they share.
Don't depend on this crate directly — the renderers re-export its entire
surface (`Rules`, `Segment`, `flatten`, ...), and this crate makes no API
stability promises of its own. It exists as a separate package only because
published crates can't share a path dependency.
Rules come in two tiers. Declarative rules (tag, attributes, text, content
slot) compile to `NodeRule`/`MarkRule` and render natively, inside the
document transaction. Callback rules defer to the caller: the renderer emits
`Segment::Deferred` entries carrying the node's type, attributes (as JSON),
and its already-rendered children, and the caller splices the result in after
the render returns — application code never runs while the document is
locked. Rules arrive as one JSON document (`Rules::parse`), so the same
format serves any binding.
## Building and testing
```bash
cargo build -p yjs-html-core
cargo test -p yjs-html-core
```
Extracted from (and maintained with) [yrby](https://github.com/jpcamara/yrby),
the Rails CRDT sync gem. MIT.