Reuse cached pointers when ordering resolution changes

docs/roadmap/remediation.md

@@ -14,12 +14,13 @@ was preserved; this review changes no production code or tests.
 The architecture now separates resolution comparison from the atomic comparator
 used by public diff. A private entry-to-final correspondence for registered
 collections feeds auditing, snapshots, metadata refresh, and shared history
-selection/replay. The main design is in place, but the following issues remain.
+selection/replay. All five findings below have now been addressed. Original
+audit observations are retained for context; completion notes describe the fixes.
 
 A follow-up integration and algorithm audit at `27be6ba`, including the same
 pre-existing working-tree changes, added Findings 4 and 5. It preserved the
-decided comparison, identity, ordering, and history policies. Findings 1–3 remain
-open; Finding 3 already covers the principal collection-size quadratic loop and
+decided comparison, identity, ordering, and history policies. Findings 1–3 were
+still open at that audit; Finding 3 covers the principal collection-size quadratic loop and
 is not duplicated below.
 
 ## Finding 1 — Metadata history rejects a valid matched historical field
@@ -225,7 +226,13 @@ adding timing thresholds or exact allocation assertions.
 
 ## Finding 5 — Delta sorting formats pointers inside every comparison
 
-**Priority:** P3. **Status:** Open; lower-priority efficiency improvement.
+**Priority:** P3. **Status:** Complete.
+
+Completion: both comparison operations share the existing decorated delta sort,
+which constructs one pointer per delta and preserves canonical pointer ordering
+and the kind tie-break. Existing comparison and diff coverage passed, along with
+`./scripts/check.sh` and the final `go test -race ./...` run. No performance
+thresholds, persistent cache, or new public contract were introduced.
 
 **Code:** [resolution comparison](../../internal/engine/resolution_compare.go),
 `compareResolutionValues` at lines 64–69; compare the existing decorated sort in
@@ -269,3 +276,15 @@ benchmark gate, or API change is needed.
   benchmarks were needed; prior successful checks apply to the unchanged
   production and test files. The amended document's links and whitespace were
   checked separately.
+
+## Remediation validation
+
+All five issues were addressed sequentially in separate nonempty commits, each
+with its completion note and relevant verification. Final validation passed
+`./scripts/check.sh` and `go test -race ./...` with Go 1.27.0 on Linux. The
+development check includes formatting, whitespace, tests, local documentation
+links, vet, and build checks. No benchmark thresholds or release gates were added.
+
+The directly related pending sensitivity regression was retained with Finding 3.
+Unrelated pre-existing documentation and public-comment changes were preserved
+outside the remediation commits.

internal/engine/document_compare.go

@@ -2,8 +2,9 @@ package engine
 
 import (
 	"cmp"
-	"go.maximumdirect.net/configkit/internal/document"
 	"slices"
+
+	"go.maximumdirect.net/configkit/internal/document"
 )
 
 type documentDeltaKind uint8
@@ -24,6 +25,10 @@ type documentDelta struct {
 func compareConfigurationValues(before, after *document.Node) []documentDelta {
 	var deltas []documentDelta
 	compareConfigurationValue(before, after, Path{}, &deltas)
+	return sortDocumentDeltas(deltas)
+}
+
+func sortDocumentDeltas(deltas []documentDelta) []documentDelta {
 	type orderedDelta struct {
 		delta   documentDelta
 		pointer string

internal/engine/resolution_compare.go

@@ -1,11 +1,6 @@
 package engine
 
-import (
-	"cmp"
-	"slices"
-
-	"go.maximumdirect.net/configkit/internal/document"
-)
+import "go.maximumdirect.net/configkit/internal/document"
 
 // compareResolutionValues reports field-level changes at stable list positions.
 func compareResolutionValues(before, after *document.Node, correspondence ...resolutionCorrespondence) []documentDelta {
@@ -61,11 +56,5 @@ func compareResolutionValues(before, after *document.Node, correspondence ...res
 		}
 	}
 	compare(before, after, Path{})
-	slices.SortFunc(deltas, func(a, b documentDelta) int {
-		if order := cmp.Compare(a.path.String(), b.path.String()); order != 0 {
-			return order
-		}
-		return int(a.kind) - int(b.kind)
-	})
-	return deltas
+	return sortDocumentDeltas(deltas)
 }