BEMJSON as the data model
Decision
Represent page content and layout as a typed BEMJSON tree. The nu engine applies templates to the tree and serializes the result as HTML.
Context
The intermediate representation determines how templates compose, how the compiler checks their inputs, and where escaping happens. nuckty needs the same block model for Markdown content and page layout.
Alternatives
String templates. Engines such as Nunjucks support escaping and template inheritance; Nunjucks enables autoescaping by default. They could render a static site, but a string-based result would need a separate structural representation for nu selectors and tree inspection.
JSX. JSX can describe typed components and does not itself require a browser runtime. Its component model is a viable alternative, but nuckty chooses selectors over named blocks, elements, and modifiers for template overriding.
HTML directly from Markdown. A Markdown-to-HTML compiler simplifies content rendering, but its output cannot be transformed with BEM selectors without first parsing HTML or retaining another tree.
Argument
BemNode describes a node's structure and template data. BEMTree is a recursive union of nodes, text, arrays, and empty positions. nu templates can replace or wrap a node before serialization, and the resolved tree can be obtained with render(tree, { templates, output: 'bemjson' }).
The same renderer processes Markdown content and document blocks. In the current HTML stage, content is rendered first and passed to the document handler as a raw node; this is a shared rendering model, not a guarantee that the entire page remains one tree until the final serialization.
The serializer centralizes text and attribute escaping and HTML minimization. Template authors still need to choose valid HTML structures and treat raw as trusted input.
Consequences
Templates operate on data rather than concatenated markup. Block declarations determine which templates and assets are loaded.
props is available to templates but is not serialized automatically. Templates may expose its values; see the data model guide. It may contain a Map, whose entries plain JSON.stringify does not preserve, so lossless tree serialization can require a custom conversion. raw is emitted without escaping or minimization. Two-pass rendering makes the resolved tree available independently of its HTML representation.