Normalize baseline and source history evidence

internal/engine/overlay.go

@@ -8,8 +8,9 @@ import (
 )
 
 type overlayRecord struct {
-	change    Change
-	displaced []displacedDefinition
+	change     Change
+	displaced  []displacedDefinition
+	introduced []historyPathOrigin
 }
 
 type displacedDefinition struct {
@@ -357,7 +358,8 @@ func mergeOverlayMappings(result *composedDocument, target, overlay *document.No
 						Path: path.clone(), Origin: incomingOrigin(incomingOrigins, path, incoming, layer),
 						Previous: previousOrigins(previous),
 					},
-					displaced: displaced,
+					displaced:  displaced,
+					introduced: overlayPathOrigins(incoming, incomingOrigins, path, layer),
 				})
 			}
 		},
@@ -395,7 +397,7 @@ func recordOverlayReplacement(
 				Path: path.clone(), Origin: incomingOrigin(incomingOrigins, path, incoming, layer),
 				Previous: previousOrigins(previous),
 			},
-			displaced: displaced,
+			displaced: displaced, introduced: overlayPathOrigins(incoming, incomingOrigins, path, layer),
 		})
 	}
 }
@@ -518,6 +520,17 @@ func collectOverlayOriginsFrom(origins, incomingOrigins map[string]Origin, node
 	collectOverlayOriginsAt(origins, incomingOrigins, node, path, path, layer)
 }
 
+func overlayPathOrigins(node *document.Node, incomingOrigins map[string]Origin, path Path, layer Layer) []historyPathOrigin {
+	var introduced []historyPathOrigin
+	walkDocument(node, path, func(affected Path, value *document.Node) {
+		introduced = append(introduced, historyPathOrigin{
+			path: affected.clone(), origin: incomingOrigin(incomingOrigins, affected, value, layer),
+			sensitive: value.Sensitive,
+		})
+	})
+	return introduced
+}
+
 func collectOverlayOriginsAt(origins, incomingOrigins map[string]Origin, node *document.Node, from, to Path, layer Layer) {
 	walkDocument(node, Path{}, func(relative Path, value *document.Node) {
 		source := appendDestination(from, relative)
@@ -633,6 +646,12 @@ func cloneOverlayRecords(records []overlayRecord) []overlayRecord {
 				path: displaced.path.clone(), origin: cloneOrigin(displaced.origin),
 			}
 		}
+		cloned[index].introduced = make([]historyPathOrigin, len(record.introduced))
+		for introducedIndex, introduced := range record.introduced {
+			cloned[index].introduced[introducedIndex] = historyPathOrigin{
+				path: introduced.path.clone(), origin: cloneOrigin(introduced.origin), sensitive: introduced.sensitive,
+			}
+		}
 	}
 	return cloned
 }