CONSUME-AS-DATA-07: Look blocks up by anchor

What it demonstrates

doc.byAnchor(id) and section-scoped byAnchor resolve any ^anchor to a kind-discriminated BlockView, declared or not.

Builds on: CONSUME-AS-DATA-06: Name two tables in one section

How it’s done

A TypeScript program against the library API; inline comments show the resulting values and behavior.

const doc = c.read(src, { path: "README.md" });

const extra = doc.byAnchor("extra");      // doc-wide; an UNdeclared ^extra table
if (extra?.kind === "table") extra.rows[1].Option; // narrow on .kind, then read

doc.byAnchor("components")?.kind;          // "table" — declared anchors resolve too
doc.body.decision.byAnchor("missing");     // undefined — scoped to one section

Surfaces exercised

• doc.byAnchor(id) doc-wide
• SectionView.byAnchor(id) scoped
• BlockView .kind discriminant + narrowing