[ixuz]

What and why

Studio's instance graph named a blank node by its label joined to its
document's address. A label may be as long as a term may be, so the
joined id could get too long to hash quickly, and building, labeling,
laying out and drawing the graph took time that grew with the square
of the number of such nodes.

Each blank node of a document now gets a short number as its id, looked
up by its document and its term as a path, never as one joined string.
The node keeps its term:

• the node pane shows a blank node's term, not its number;
• the layout orders blank nodes by document, then term, so where a
  cycle breaks still doesn't depend on unrelated nodes;
• the search finds a blank node by its term or its document's address;
• a kept layout is reused only for a graph with the same blank labels.

The Studio also counts the labels it tells apart by a path of file name
and label. docs/deck-library.md and docs/studio.md describe the new ids.
The node= route parameter of a blank node now holds its number, which
stays valid while the instance's data stays the same.

Refs: GHSA-6qgg-9wcf-9vqr