diff --git a/docs/roadmap/remediation.md b/docs/roadmap/remediation.md
index 11489b6..2b1f2a7 100644
--- a/docs/roadmap/remediation.md
+++ b/docs/roadmap/remediation.md
@@ -266,7 +266,15 @@ coverage; do not add timing thresholds or implementation-specific scan counts.
 
 ## 5. Prefix Indexing Multiplies One Operation By All Its Descendants
 
-Priority: P2. Status: open.
+Priority: P2. Status: complete.
+
+Completion: indexes locate concrete affected paths rather than placing every
+descendant at the reported ancestor. Exact path buckets drive source-origin
+containment (with early success); enclosing queries visit only their affected
+subtree. Logical operations remain payload references, deduplicated once by the
+common selector. Thus a leaf no longer scans sibling facts of an ancestor
+replacement. The full ordinary suite and `git diff --check` passed, including
+parsed key/index sides, removed descendants, inheritance, and enclosing queries.
 
 Relevant code: `addObservation` in
 [history_model.go](../../internal/engine/history_model.go), lines 116–139;
diff --git a/internal/engine/history_model.go b/internal/engine/history_model.go
index 5a44b81..97540b8 100644
--- a/internal/engine/history_model.go
+++ b/internal/engine/history_model.go
@@ -69,7 +69,7 @@ type historyModel struct {
 	shapesByPointer       map[string][]Path
 	shapeOrder            []Path
 	observationsByPointer map[string][]int
-	reportedPathIndex     pathPrefixIndex
+	affectedPathIndex     pathPrefixIndex
 	documentLookup        *documentLookup
 
 	frozen bool
@@ -127,14 +127,14 @@ func (builder *historyBuilder) addObservation(observation historyObservation) in
 	builder.model.observations = append(builder.model.observations, observation)
 	builder.addShape(observation.path)
 	switch observation.role {
-	case historyRoleDefinition, historyRoleContribution, historyRoleCompositeDefinition, historyRoleCheckpoint:
+	case historyRoleDefinition, historyRoleContribution, historyRoleCompositeDefinition, historyRoleCheckpoint, historyRoleOperation, historyRoleControl:
 		pointer := observation.path.String()
 		builder.model.observationsByPointer[pointer] = append(builder.model.observationsByPointer[pointer], observationID)
-		if observation.role == historyRoleContribution {
-			builder.model.reportedPathIndex.insert(pointer, observationID)
+		if observation.role == historyRoleContribution || observation.role == historyRoleOperation || observation.role == historyRoleControl {
+			// Index the concrete affected path, not the common reported ancestor.
+			// A leaf query must not enumerate every sibling fact of one operation.
+			builder.model.affectedPathIndex.insert(pointer, observationID)
 		}
-	case historyRoleOperation, historyRoleControl:
-		builder.model.reportedPathIndex.insert(observation.reportedPath.String(), observationID)
 	}
 	return observationID
 }
diff --git a/internal/engine/history_select.go b/internal/engine/history_select.go
index 83646ba..7affcff 100644
--- a/internal/engine/history_select.go
+++ b/internal/engine/history_select.go
@@ -36,10 +36,10 @@ func (model *historyModel) selectHistory(path Path) []historySelection {
 	for _, observationID := range model.observationsByPointer[path.String()] {
 		candidateSet[observationID] = struct{}{}
 	}
-	model.reportedPathIndex.visitAncestors(path.String(), func(observationID int) {
-		candidateSet[observationID] = struct{}{}
-	})
-	model.reportedPathIndex.visitDescendants(path.String(), func(observationID int) {
+	// Producers register all affected before/after paths. Exact facts cover
+	// ancestor replacements; descendants cover operations within an enclosing
+	// query. Logical operations are still deduplicated by payload below.
+	model.affectedPathIndex.visitDescendants(path.String(), func(observationID int) {
 		candidateSet[observationID] = struct{}{}
 	})
 	candidates := make([]int, 0, len(candidateSet))
diff --git a/internal/engine/history_source.go b/internal/engine/history_source.go
index b0f7870..30f7c34 100644
--- a/internal/engine/history_source.go
+++ b/internal/engine/history_source.go
@@ -192,26 +192,25 @@ func sourceApplicationOrigin(application historyApplication, node *document.Node
 }
 
 func sourceOriginRepresentedByOperation(model *historyModel, path Path, origin Origin) bool {
-	represented := false
-	model.reportedPathIndex.visitAncestors(path.String(), func(observationID int) {
+	for _, observationID := range model.observationsByPointer[path.String()] {
 		observation := model.observations[observationID]
 		if observation.phase != historyPhaseSources || observation.role != historyRoleOperation {
-			return
+			continue
 		}
 		if !observation.afterPresent || !sameConcreteHistoryPath(path, observation.path) {
-			return
+			continue
 		}
 		operationOrigin, ok := model.resolveAttribution(observation.attributionRef)
 		if !ok {
-			return
+			continue
 		}
 		if originRepresentedByChange(path, origin, Change{
 			Path: observation.reportedPath, Origin: operationOrigin.origin,
 		}) {
-			represented = true
+			return true
 		}
-	})
-	return represented
+	}
+	return false
 }
 
 func originRepresentedByChange(path Path, origin Origin, change Change) bool {