Graph math lives in graph_traversal, not in the navigator tabs

Tree and Sankey share visit-based Adjust, display-set, and node-link payload helpers; unique-process (one box per process) is a Sankey concern. Those helpers live in bwutils/graph_traversal/ so the Qt pages stay widgets. The engine has no unique_activities flag — Sankey wraps the engine, then collapses to the highest-

path impact

visit per process.

Status

accepted

Considered Options

• Keep one Tree-named helper module for both tabs (rejected: name fights the glossary; unique-process looks like a contribution-tree flag).
• Put graph math on the Sankey navigator tab (rejected: ADR-0001; widgets must not own traversal).
• Four modules under graph_traversal: engine, tree, sankey, partition_plots (chosen).