Function render_entity_markdown 

pub fn render_entity_markdown(
    entity: &Entity,
    sections_filter: Option<&[String]>,
) -> String

Render a single entity as markdown with frontmatter metadata.

Projection-free by contract: this is the canonical form (anchor hashing, export, parser round-trips). Serving surfaces that present declared signals or the grounded labelling call render_entity_markdown_with_signals instead — computed values are a projection and must never enter the canonical bytes.