Reference resolution as one rule (spec/14 §19.6, D-103): every library id at a reference site of a flat design is resolved through a store, so that what leaves Visualize.Chart.flatten/2 carries no ids and what the frame draws needs no store.

A {:style, n} at a style site — a mark's, an axis's, a label's style, alone or in a stack (§3.6) — becomes the entry's body inline, since a style site already takes a node. A {:scale, n} or {:source, n} at a single-valued site — an axis's scale, a mark's data, a mark's scales.x — is declared in the design's namespace for the kind under a synthesised key, :"scale:4", the word the DOM already uses for the id, and the site is rewritten to that key. A body that is itself a composite is flattened first.

An id the store no longer holds is a mask at the site (§19.2, D-100): a style entry becomes nothing, a single-valued site is removed so the kind's default or the validator's fault applies, and the id is reported. Rendering never fails on a stale reference and never draws less than it says.