[endrix]

What

Edges that leave one port together run along one line until they split, and so do edges that reach one port. Each edge wrote its carried label at its own midpoint, and the midpoints of such a bundle all fall on the shared line. On an NDF ASL unit with 23 dependencies, that stacked 23 copies of depends-on on one trunk.

clientBehavior.edgeCaptions: 'once' writes the label once per bundle. An edge leaves its caption out when an earlier edge (in model order) that leaves the same port, or reaches the same port, already writes the same text. Edges with other captions keep theirs, and so does an edge alone on its ports. The decision is made once per model root and reused for every edge (edge-caption-sharing.ts).

An edge whose caption is not written, whether shared or because captions are off, now says what it carries in its hover tooltip, as the flag's documentation already promised. The label-or-width rule moves to carriedTextOf, which the edge view and the sharing decision both use. true (the default) and false behave as before; 'once' is opt-in.

Tests

• diagram-client/test/edge-caption-sharing.test.ts covers:
  • bundles leaving a port and bundles reaching one;
  • different captions and lone edges keeping theirs;
  • only captions actually written counting;
  • the label-or-width rule;
  • one decision per model root, made afresh for a new root;
  • the edge view's wiring.
• Typecheck (5/5), neutrality (5/5) and all workspace tests (1236) pass.

Checked visually with scripts/render-svg, through ndf-ide, on pto-spec's expansion.asl (18 incoming and 5 outgoing depends-on edges, now one caption on each trunk, with defined-in kept) and expdif.asl.

https://claude.ai/code/session_01E8WfqKknDNN6xpNVcJL5K8