Index inheritance history lookups

internal/engine/metadata.go

@@ -9,11 +9,12 @@ import (
 // Metadata provides detached effective presence/origin and chronological history
 // queries for a load. Its zero value contains no paths.
 type Metadata struct {
-	effectivePaths  map[string]Path
-	historicalPaths map[string][]Path
-	fields          map[string]FieldInfo
-	history         map[string][]Change
-	inheritance     []inheritanceOperation
+	effectivePaths   map[string]Path
+	historicalPaths  map[string][]Path
+	fields           map[string]FieldInfo
+	history          map[string][]Change
+	inheritance      []inheritanceOperation
+	inheritanceIndex *inheritanceHistoryIndex
 }
 
 // Lookup returns information for an effective path. Unknown and invalid paths
@@ -57,7 +58,11 @@ func (m Metadata) History(path Path) []Change {
 		return nil
 	}
 	history := m.history[path.String()]
-	return historyWithInheritance(path, history, m.inheritance)
+	operations := m.inheritance
+	if m.inheritanceIndex != nil {
+		operations = m.inheritanceIndex.matchingOperations(path, m.inheritance)
+	}
+	return historyWithInheritance(path, history, operations)
 }
 
 // HistoricalPaths returns the paths observed during loading, including effective
@@ -161,6 +166,7 @@ func finalizeMetadataPaths(m *Metadata, final *document.Node, applications []his
 			walkDocument(operation.effective, operation.transfer.to, add)
 		}
 	}
+	m.inheritanceIndex = newInheritanceHistoryIndex(m.inheritance)
 }
 
 // effectivePathIndex records document-derived paths with their contextual segment