Index import dependencies for local scope scheduling

docs/internal/imports.md

@@ -72,6 +72,12 @@ tuple comparisons. On a stalled graph, deterministic DFS over the residual graph
 returns a closed cycle rotated to its smallest key; blocked dependents are not
 reported as cycle members.
 
+Import edge preparation builds an importer-to-target adjacency index once for
+an acquisition's outer and item-local scheduling, and once for grouped
+scheduling. Each scope gathers edges from its participating identities and
+retains only edges with both endpoints in its local slots. The retained
+inclusion graph still owns cycle diagnostics and source relationships.
+
 Import composition schedules a main tier or one underlay group as a single
 strict-scope graph. Applicable collection declarations are gathered for the
 scope before peer composition, including identity inherited from lower tiers.