Fix nested inheritance history and budget accounting

docs/roadmap/remediation.md

@@ -3,8 +3,31 @@
 Reviewed implementation commits `78d4b59` through `2ca1f80` against the
 [feature roadmap](named-inheritance.md), [implementation plan](implementation.md),
 and the user's agreed sibling lookup, enclosing-first expansion, presence, and
-provenance decisions. Both findings below require remediation. No implementation
-fixes are included in this review.
+provenance decisions. Both findings below are now resolved. The original review
+evidence is retained below; source line references identify the reviewed baseline.
+
+## Resolution — 2026-09-30
+
+- The destination walker now detaches each mapping/sequence container before
+  replacing its child pointers. Retained enclosing templates remain immutable;
+  untouched subtrees remain shared, with existing retained-history accounting.
+  Regressions check value introduction, inherited control arrival/consumption,
+  container explanations, a three-generation chain, and sequence-contained scopes.
+  The nested-history regression failed before the fix and passes afterward.
+- Budget accounting now maintains one logical document total and updates it from
+  old/new scope counts. Each scope receives the budget remaining after other
+  branches are reserved. Early expansion checks and final node/depth validation
+  remain in place. Boundary tests include independent scopes inside sequences,
+  unchanged sibling data, and consumed null directives.
+- The maintained `BenchmarkInheritanceIndependentScopes` covers 256, 512, and
+  1,024 independent scopes. Allocations measured approximately 8.95, 17.87, and
+  36.12 MB/op respectively: roughly proportional to scope count. This benchmark
+  has a larger per-scope payload than the original review probe, so absolute
+  values are not a before/after comparison. No timing threshold was introduced.
+- Validation after the fixes: `./scripts/check.sh`, `go test -race ./...`,
+  the new independent-scope benchmark, and the existing expansion/inspected-load
+  benchmarks passed on Linux. Existing redaction, ownership, and history-budget
+  tests remain passing; no public contract or limit was changed.
 
 ## 1. Preserve immutable enclosing snapshots during nested resolution