Localize history selection to affected paths

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;