Record import graph completion

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Implementation Plan: Import Discovery and Dependency-Ready Ordering
 
-Status: Stages 1–3 complete; 16 implementation stages remain.
+Status: Stages 1–4 complete; 15 implementation stages remain.
 
 ## Authority, baseline, and execution
 
@@ -291,6 +291,13 @@ routes. Do not expand successful shared dependency support for imports.
 Acceptance: current ordinary/item import behavior tests pass, including a cycle
 through a nested item scope, repeated imports, source IDs, and handle closure.
 
+Completion: implemented in commit `fbe9ae6` (`Retain import inclusion graph
+during acquisition`). Verified with `go test ./internal/engine -count=1`,
+`./scripts/check.sh`, and `git diff --check`. Import acquisition retains stable
+source keys, roles, inclusion edges, and explicit scope ownership; item
+scopes are composed after discovery in the existing contribution order.
+Non-active repeats remain invalid. Stage 5 onward remains.
+
 ## Stage 5 — Schedule ordinary main-tier contributions
 
 Use the shared scheduler for ordinary mapping contributions in the main tier.