Share self-contained schema compilation

docs/roadmap/implementation.md

@@ -314,6 +314,10 @@ framing, containment, and freezing cases. External-reference successes become
 expected errors. Root compilation alone is intentionally not the completed
 self-containment remedy; Stage 12 checks otherwise unused schema declarations.
 
+Completion: host and filesystem validation share root-document compilation with
+a context-aware external-resource rejection loader. Focused validation tests
+pass on Go 1.27.3; checking unused declarations remains in the following unit.
+
 ## Stage 12: Check Declared Schema Locations Through The Compiler
 
 **Catalog:** 6, 21, resource-policy completion. **Scope:** schema-location traversal.