Preserve child identity in inheritance history

internal/engine/inheritance_schedule.go

@@ -231,6 +231,12 @@ func applyInheritanceScopeTemplates(adapter inheritanceScopeAdapter, order []int
 				parentPolicyScope, replaced = lowerCollectionPoliciesForClaims(parentPolicyScope, claims.ordered, declarations, adapter.applicationPolicy())
 			}
 			merged := inheritanceParentPayload(parent, node.identityFields)
+			historyParent := parent
+			if len(node.identityFields) != 0 {
+				// The retained parent snapshot is the inherited payload, before
+				// child fields are applied, with parent identity excluded.
+				historyParent = document.Clone(merged)
+			}
 			mergedPolicyScope, policyDiagnostics := mergeInheritanceCollectionPolicies(
 				parentPolicyScope, childPolicyScope, node.path, parent, payload, adapter.applicationPolicy(), replaced,
 			)
@@ -316,12 +322,13 @@ func applyInheritanceScopeTemplates(adapter inheritanceScopeAdapter, order []int
 			resolvedPolicies[index] = inheritancePolicyScopeAtPath(mergedPolicyScope, node.path)
 			result.transfers = append(result.transfers, transfer)
 			result.operations = append(result.operations, inheritanceOperation{
-				transfer: &transfer, parent: parent, effective: merged,
+				transfer: &transfer, parent: historyParent, effective: merged,
 				parentOrigins: resolvedOrigins[node.parent], effectiveOrigins: mergedOrigins,
 				parentPolicies:    cloneInheritancePolicyTemplates(parentPolicies),
 				templatePolicies:  cloneCollectionPolicyScopeForInheritance(templatePolicies),
 				effectivePolicies: cloneInheritancePolicyTemplates(effectivePolicies),
 				sequences:         cloneSequenceHistoryContributions(sequenceContributions),
+				identityFields:    cloneStrings(node.identityFields),
 			})
 			resolvedPolicyTemplates[index] = effectivePolicies
 		} else {