Index mappings while assembling configuration reports

docs/roadmap/remediation.md

@@ -1,7 +1,7 @@
 # Configuration comparison review remediation
 
-Status: four open findings. This document records required follow-up work; it
-does not implement the fixes.
+Status: one finding complete; three open. This document tracks required
+follow-up work and its completion evidence.
 
 ## Review baseline and scope
 
@@ -39,7 +39,7 @@ caller-owned aliases/caches are deliberate choices and require no remediation.
 
 ## R-1: Avoid repeated full scans when assembling wide report mappings
 
-**Status:** Open. **Priority:** Medium. **Category:** Code quality / efficiency.
+**Status:** Complete. **Priority:** Medium. **Category:** Code quality / efficiency.
 
 **Evidence:** [diff_report.go](../../integrations/ckconfig/diff_report.go),
 `placeYAMLValue` and `mappingKeyIndex` (lines 59 and 98 at the review baseline).
@@ -62,6 +62,15 @@ the accumulated mapping. Existing semantic-path, YAML-type, ordering, and native
 safe-value behavior remains intact. Any additional measurement should be focused
 on this lookup cost; a numerical performance gate is not required.
 
+**Completed 2026-10-12:** A private, report-local `yamlValuePlacer` now indexes
+each encountered mapping once and updates that index as keys are appended.
+Subsequent placements reuse key positions while YAML content keeps insertion
+order. Root values, native regions, and incompatible-ancestor failures retain
+their handling. Existing helper tests use the same placer across placements.
+`go test ./...` passed in `integrations/ckconfig`, including the simple consumer;
+the diff and whitespace review passed. No public API, limits, global cache,
+benchmark, or performance gate was added.
+
 ## R-2: Scope CLI guarantees to the actual provider and delivery boundaries
 
 **Status:** Open. **Priority:** Medium. **Category:** Inadvertently strengthened