Preserve resource field presence in lists

docs/roadmap/implementation.md

@@ -271,6 +271,13 @@ Scope: backend/profile field capture, normalization, and defaulting in
 Validation: owning tests demonstrate explicit zeros/nulls, backend completion,
 and recorded normalization at the correct list entries. No new readiness rule.
 
+Completion: backend and profile presence capture and resolution now use list
+indexes and mutate the effective slice elements while retaining full-ID state
+keys. Converted focused normalization, null/default, profile-presence, and
+same-ID replacement fixtures. Their execution remains deferred: the package
+still does not compile until the subsequent indexing, validation, and prompt
+list migrations. Formatting and `git diff --check` passed.
+
 ## Stage 5: Validate Final Records And Build Execution Indexes
 
 Scope: `validateEffective`, `indexedBackends`, `indexedProfiles`, and