diff --git a/docs/development.md b/docs/development.md
index e7064ae..bb74b59 100644
--- a/docs/development.md
+++ b/docs/development.md
@@ -232,6 +232,7 @@ code changes. Use the component overview to find the corresponding implementatio
 | Effective configuration diff | [Engine comparison and masking tests](../internal/engine/diff_test.go), [engine operation tests](../internal/engine/diff_operation_test.go), [root facade tests](../facade_diff_test.go), and [consumer examples](../examples/consumers/diff_test.go) | `go test ./internal/engine -run 'Diff|Explain|History|Secret|Independent'`, `go test . -run 'Diff|FacadeInspection|PublicFacadeBoundary|DependencyImportBoundary'`, `go test ./examples/consumers`, and `go test . -run '^ExampleDiff$'` |
 | Consumer examples and migration fixtures | [Consumer tests](../examples/consumers/consumers_test.go), [native, layered, and ordinary relative-import examples](../examples/consumers/layered_test.go), [mounted collection examples](../examples/consumers/destinations_test.go), [API examples](../example_test.go) | `go test ./examples/consumers` and `go test . -run '^Example'` |
 | Assembly and layered scaling evidence | [Assembly benchmarks](../internal/engine/assembly_bench_test.go), [layered benchmarks](../internal/engine/underlay_bench_test.go) | `go test ./internal/engine -run '^$' -bench '^BenchmarkUnderlay' -benchmem`; repeat with `^BenchmarkCompose` and `^BenchmarkOverlay` |
+| Identified-sequence scaling evidence | [Mixed-upsert benchmark](../internal/engine/sequence_combine_bench_test.go) | `go test ./internal/engine -run '^$' -bench '^BenchmarkSequenceMixedUpsert$' -benchmem` |
 | Inheritance scaling evidence | [Expansion benchmarks](../internal/engine/inheritance_bench_test.go) | `go test ./internal/engine -run '^$' -bench '^BenchmarkInheritance' -benchmem` |
 | Documentation links and dependency isolation | [Link checks](../documentation_test.go), [import boundary](../import_boundary_test.go), [public boundary](../public_boundary_test.go) | `go test . -run 'TestLocalDocumentationLinks\|TestDependencyImportBoundary\|TestPublicFacadeBoundary'` |
 | Development check behavior | [Development checker test](../development_check_test.go) | `go test . -run '^TestDevelopmentCheckHandlesFilenamesAndStopsOnFailure$'` |
diff --git a/docs/roadmap/implementation.md b/docs/roadmap/implementation.md
index d8763f5..b91ce9a 100644
--- a/docs/roadmap/implementation.md
+++ b/docs/roadmap/implementation.md
@@ -1,6 +1,6 @@
 # Sequence Identity And Combination Implementation Plan
 
-Status: implementation in progress; Stages 1–29 complete.
+Status: all thirty stages complete.
 
 Audience: a Luna coding agent implementing one numbered stage per prompt, in
 order. This plan starts at commit
@@ -1031,6 +1031,37 @@ from Stages 28–29 if their covered content is unchanged. Record completed scop
 validation, benchmark commands/qualitative findings, and any real remaining
 issues accurately. No new timing thresholds or release gates are introduced.
 
+**Completion:** Audited the shared indexed sequence-combination and identity
+validation paths, declaration gathering, numeric normalization, ownership and
+selector-path handling, adapters, dependencies, boundaries, and limits. Removed
+per-declaration temporary-slice allocation while retaining detached declaration
+ownership. Added a mixed-size identified-sequence upsert benchmark because the
+existing assembly benchmarks did not exercise this path. Its allocations grew
+roughly in proportion to record count from 128 to 2,048 records; elapsed times
+were similarly proportional in this short run and are descriptive only.
+
+Benchmark command:
+
+```sh
+go test ./internal/engine -run '^$' -bench '^(BenchmarkComposeWideMappings|BenchmarkUnderlay(BroadCatalog|ManySmallTiers)|BenchmarkOverlay(RecursiveMappings|ManyApplications)|BenchmarkInheritance(Expansion|IndependentScopes)|BenchmarkSequenceMixedUpsert)$' -benchmem -benchtime=100ms
+```
+
+The benchmark reported mixed-upsert results of 278,009 B and 2,337 allocations
+per operation at 128 records; 1,122,177 B and 9,253 allocations at 512; and
+4,521,839 B and 36,925 allocations at 2,048. No thresholds are implied. The
+code review found shared combination and identity algorithms, indexed matching
+and mapping access, declaration grouping by destination, coefficient/exponent
+numeric normalization without magnitude expansion, operation-local ownership
+and selector traversal, no remaining early-CLI adapter, and no newly introduced
+dependencies, public internal types, background work, release machinery, or
+sequence-specific resource limits. Obsolete registration names remain only in
+historical or roadmap text.
+
+Verified with `./scripts/check.sh`, `go test -race ./...`,
+`go test . -run 'TestLocalDocumentationLinks|TestDependencyImportBoundary|TestPublicFacadeBoundary' -count=1`,
+`git diff --check`, and the benchmark command above. No remaining implementation
+issues were found.
+
 Acceptance: all roadmap operations and lifecycle boundaries work through ordinary
 and layered loads; values and inspection agree; application constraints hold on
 successful final results; deferred behavior and YAML-only guarantees have not
diff --git a/internal/engine/imports.go b/internal/engine/imports.go
index eb0a4a3..a9eb140 100644
--- a/internal/engine/imports.go
+++ b/internal/engine/imports.go
@@ -812,11 +812,11 @@ func (s *importTraversal) composePendingItems(scope *acquisitionScope, policy se
 func acquiredSequenceDeclarations(scope acquisitionScope) []sequenceDeclarationSpec {
 	var declarations []sequenceDeclarationSpec
 	for _, contribution := range scope.contributions {
-		for _, declaration := range contribution.sequenceDeclarations {
-			projected := cloneSequenceDeclarations([]sequenceDeclarationSpec{declaration})[0]
-			projected.destination = appendDestination(contribution.relativeDestination, declaration.destination)
-			declarations = append(declarations, projected)
+		projected := cloneSequenceDeclarations(contribution.sequenceDeclarations)
+		for index := range projected {
+			projected[index].destination = appendDestination(contribution.relativeDestination, projected[index].destination)
 		}
+		declarations = append(declarations, projected...)
 	}
 	return declarations
 }
diff --git a/internal/engine/sequence_combine_bench_test.go b/internal/engine/sequence_combine_bench_test.go
new file mode 100644
index 0000000..f0cc8fa
--- /dev/null
+++ b/internal/engine/sequence_combine_bench_test.go
@@ -0,0 +1,42 @@
+package engine
+
+import (
+	"strconv"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/ConfigKit/internal/document"
+)
+
+func BenchmarkSequenceMixedUpsert(b *testing.B) {
+	for _, size := range []int{128, 512, 2048} {
+		b.Run(strconv.Itoa(size), func(b *testing.B) {
+			lower := benchmarkSequenceRecords(0, size, "lower")
+			higher := benchmarkSequenceRecords(size/2, size, "higher")
+			context := sequenceCombinationContext{destination: Keys("items")}
+			identityFields := []string{"id"}
+			b.ReportAllocs()
+			b.ResetTimer()
+			for range b.N {
+				if _, diagnostics := combineIdentifiedSequences(
+					lower, higher, sequenceModeUpsert, identityFields, context,
+				); len(diagnostics) != 0 {
+					b.Fatal(diagnostics)
+				}
+			}
+		})
+	}
+}
+
+func benchmarkSequenceRecords(start, count int, value string) *document.Node {
+	items := make([]*document.Node, count)
+	for index := range count {
+		items[index] = &document.Node{
+			Kind: document.Mapping,
+			Mapping: []document.Entry{
+				{Key: "id", Value: &document.Node{Kind: document.String, Text: "item-" + strconv.Itoa(start+index)}},
+				{Key: "value", Value: &document.Node{Kind: document.String, Text: value}},
+			},
+		}
+	}
+	return &document.Node{Kind: document.Sequence, Sequence: items}
+}