The builder's import and export: the design's JSON form, in and out (spec/14 §18.12).

Export is Visualize.Chart.to_json/1 of the stacked design, and it therefore demands a design: the stack goes through Visualize.Chart.from_map/1 first, and a fragment that does not validate is its errors, listed by path exactly as the preview lists them. Import reads a pasted document through Visualize.Chart.from_json/1, and the design it yields becomes the builder's single layer, since a document is a whole design and not a layer of somebody else's stack (D-88).

Both are behind the optional Jason dependency: without it each reports {:missing_dependency, :jason} in the panel rather than raising, which is what an optional dependency means.

This module compiles only when Phoenix.Component is loaded (spec/10 §1.1, D-45, D-85).