Validate source equivalence and layered scaling

2026-09-29 18:15:10 +00:00
parent 36362ee6af
commit 34e18c84c1
6 changed files with 423 additions and 13 deletions
--- a/docs/roadmap/implementation.md
+++ b/docs/roadmap/implementation.md
@@ -461,6 +461,28 @@ checker and full race suite.

 ## Stage 9: Validate cross-feature consistency and scaling

+**Completed 2026-09-29.** A compact public matrix now checks equivalent host,
+native, byte, reader, and mapping inputs; tier-local repetition versus cross-tier
+reuse; reader consumption; and safe diagnostics/effective/history output after
+secret replacement. Engine tests verify exact occurrence accounting across
+imports, shared glob/source limits, and the mixed-source CLI ceiling. Rendering
+now indexes source labels once per explanation instead of scanning all records
+for every location. Loading and passive context ownership were reviewed against
+ADR 0008; no handles or background work are retained by queries.
+
+On Linux amd64 with `-benchmem` and 100 ms samples, the 512-entry assembly-only
+composition measured about 3.5 ms/op (the earlier post-index baseline was about
+3.3 ms), and recursive overlay about 2.2 ms/op (about 12 ms at the first-stage
+handoff before subsequent provenance work). The 128-application owned assembly
+remained about 0.30 ms/op versus 6.35 ms/op for copy-preserving application.
+End-to-end layered measurements were about 7.15 ms/op for 512 broad catalog
+entries, 2.59 ms/op for 128 small tiers, 3.27 ms/op for 128 alternating subtree
+replacements, 1.86 ms/op for 64 imported native defaults, and 1.36 ms/op for
+64 retained-history applications. Allocations grew roughly with these fixture
+sizes. I/O, sorting, decoding, callbacks, and retained output contribute to
+full-path cost; these observations are not timing gates or an unconditional
+complexity guarantee. The everyday checker and full race suite passed.
+
 1. Consolidate a small semantic equivalence matrix across host, native, bytes,
   readers, and mappings, using equivalent logical inputs and contexts. Cover
   strict conflict versus intentional precedence and version-path preservation;
--- a/facade_equivalence_test.go
+++ b/facade_equivalence_test.go
@@ -0,0 +1,164 @@
+package configkit_test
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"testing"
+	"testing/fstest"
+
+	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+)
+
+type equivalentConfig struct {
+	Version  uint64   `yaml:"version"`
+	Name     string   `yaml:"name"`
+	Enabled  bool     `yaml:"enabled"`
+	Count    int      `yaml:"count"`
+	Items    []string `yaml:"items"`
+	Optional *string  `yaml:"optional"`
+}
+
+func TestEquivalentSourceFormsPreserveInputSemantics(t *testing.T) {
+	const yaml = "version: 1\nname: retained\nenabled: false\ncount: 0\nitems: []\noptional: null\n"
+	hostPath := filepath.Join(t.TempDir(), "main.yml")
+	if err := os.WriteFile(hostPath, []byte(yaml), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	namespace := configkit.NewFilesystem("bundle", fstest.MapFS{"main.yml": &fstest.MapFile{Data: []byte(yaml)}})
+	context := &configkit.FilesystemContext{Root: ".", BaseDir: ".", FS: &namespace}
+	for _, test := range []struct {
+		name    string
+		source  configkit.Source
+		context *configkit.FilesystemContext
+		kind    configkit.SourceKind
+	}{
+		{"host", configkit.File(hostPath), nil, configkit.SourceKindFile},
+		{"native", namespace.File("main.yml"), nil, configkit.SourceKindFilesystem},
+		{"bytes", configkit.Bytes("memory", []byte(yaml)), context, configkit.SourceKindBytes},
+		{"reader", configkit.Reader("stream", strings.NewReader(yaml)), context, configkit.SourceKindReader},
+		{"mapping", configkit.Mapping("programmatic", map[string]any{
+			"version": uint64(1), "name": "retained", "enabled": false, "count": 0,
+			"items": []any{}, "optional": nil,
+		}), context, configkit.SourceKindMapping},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			checks := 0
+			result, err := configkit.LoadLayered(configkit.Input{Source: test.source, Filesystem: test.context}, configkit.LayeredOptions[equivalentConfig]{
+				Definition: configkit.Definition[equivalentConfig]{Version: &configkit.VersionRule{
+					Path: configkit.Keys("version"), Check: func(version configkit.Version, validation *configkit.Validation) error {
+						checks++
+						if !version.Present || version.Text != "1" {
+							t.Errorf("version = %#v", version)
+						}
+						return nil
+					},
+				}},
+			})
+			if err != nil {
+				t.Fatal(err)
+			}
+			want := equivalentConfig{Version: 1, Name: "retained", Items: []string{}}
+			if !reflect.DeepEqual(result.Config, want) || checks != 1 {
+				t.Fatalf("config = %#v, checks %d", result.Config, checks)
+			}
+			for _, field := range []string{"version", "name", "enabled", "count", "items", "optional"} {
+				info, ok := result.Metadata().Lookup(configkit.Keys(field))
+				if !ok || !info.Explicit || info.Origin.Layer != configkit.LayerBase || info.Null != (field == "optional") {
+					t.Errorf("%s input info = %#v, %v", field, info, ok)
+				}
+			}
+			sources := result.Sources()
+			if len(sources) != 1 || sources[0].Kind != test.kind || sources[0].ID != "source-1" || sources[0].UnderlayIndex != 0 {
+				t.Fatalf("sources = %#v", sources)
+			}
+			resource, ok := result.SourceContext("source-1")
+			if !ok || resource.BaseDir != "." || resource.FS == nil {
+				t.Fatalf("source context = %#v, %v", resource, ok)
+			}
+		})
+	}
+}
+
+func TestRepeatedImportsAcrossTiersAndReaderConsumption(t *testing.T) {
+	namespace := configkit.NewFilesystem("bundle", fstest.MapFS{
+		"left.yml":   &fstest.MapFile{Data: []byte("configkit: {imports: [{path: shared.yml}]}\n")},
+		"right.yml":  &fstest.MapFile{Data: []byte("configkit: {imports: [{path: shared.yml}]}\n")},
+		"shared.yml": &fstest.MapFile{Data: []byte("name: retained\n")},
+	})
+	type config struct {
+		Name string `yaml:"name"`
+	}
+	left := configkit.Input{Source: namespace.File("left.yml"), Imports: true}
+	right := configkit.Input{Source: namespace.File("right.yml"), Imports: true}
+	_, err := configkit.LoadLayered(configkit.Input{Source: configkit.NoSource()}, configkit.LayeredOptions[config]{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{left, right}}},
+	})
+	if got := layeredErrorCode(t, err); got != configkit.CodeImportRepeated {
+		t.Fatalf("same-tier repeated import = %s", got)
+	}
+	result, err := configkit.LoadLayered(configkit.Input{Source: configkit.NoSource()}, configkit.LayeredOptions[config]{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{left}}, {Inputs: []configkit.Input{right}}},
+	})
+	if err != nil || result.Config.Name != "retained" || len(result.Sources()) != 4 {
+		t.Fatalf("cross-tier repeated import = %#v, %v", result, err)
+	}
+	reader := configkit.Reader("single-use", strings.NewReader("name: retained\n"))
+	_, err = configkit.LoadLayered(configkit.Input{Source: configkit.NoSource()}, configkit.LayeredOptions[config]{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{Source: reader}}}, {Inputs: []configkit.Input{{Source: reader}}}},
+	})
+	if got := layeredErrorCode(t, err); got != configkit.CodeSourceReaderUsed {
+		t.Fatalf("reader re-consumption = %s", got)
+	}
+}
+
+func TestReplacedSecretRemainsAbsentFromSafeOutput(t *testing.T) {
+	type config struct {
+		Secret string `yaml:"secret"`
+	}
+	result, err := configkit.LoadLayered(configkit.Input{Source: configkit.Bytes("main", []byte("secret: new-secret-canary\n"))}, configkit.LayeredOptions[config]{
+		Underlays:  []configkit.Underlay{{Inputs: []configkit.Input{{Source: configkit.Mapping("lower", map[string]any{"secret": "old-secret-canary"})}}}},
+		Definition: configkit.Definition[config]{Secret: func(path configkit.Path) bool { return path.String() == "/secret" }},
+	})
+	if err != nil || result.Config.Secret != "new-secret-canary" {
+		t.Fatalf("secret load = %#v, %v", result, err)
+	}
+	var effective, history bytes.Buffer
+	if err := result.WriteEffective(&effective); err != nil {
+		t.Fatal(err)
+	}
+	if err := result.WriteExplanation(&history, configkit.Keys("secret")); err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(effective.String()+history.String(), "old-secret-canary") || strings.Contains(effective.String()+history.String(), "new-secret-canary") {
+		t.Fatalf("secret output leaked: %q %q", effective.String(), history.String())
+	}
+	_, err = configkit.LoadLayered(configkit.Input{Source: configkit.Bytes("main", []byte("secret: new-secret-canary\n"))}, configkit.LayeredOptions[config]{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{Source: configkit.Mapping("lower", map[string]any{"secret": "old-secret-canary"})}}}},
+		Definition: configkit.Definition[config]{Validate: func(config *config, validation *configkit.Validation) {
+			validation.Error(configkit.Keys("secret"), "invalid secret")
+		}},
+	})
+	loadError, ok := err.(*configkit.LoadError)
+	if !ok {
+		t.Fatalf("validation error = %#v", err)
+	}
+	var diagnostics bytes.Buffer
+	if err := configkit.WriteDiagnostics(&diagnostics, loadError.Diagnostics()); err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(diagnostics.String(), "secret-canary") {
+		t.Fatalf("diagnostic leaked secret: %q", diagnostics.String())
+	}
+}
+
+func layeredErrorCode(t *testing.T, err error) configkit.Code {
+	t.Helper()
+	loadError, ok := err.(*configkit.LoadError)
+	if !ok || len(loadError.Diagnostics()) == 0 {
+		t.Fatalf("load error = %#v", err)
+	}
+	return loadError.Diagnostics()[0].Code
+}
--- a/internal/engine/explain_render.go
+++ b/internal/engine/explain_render.go
@@ -23,10 +23,14 @@ func (r *Inspection) WriteExplanation(output io.Writer, path Path) error {
 		return errExplanationUnknownPath
 	}
 	var rendered strings.Builder
+	labels := make(map[string]string, len(r.sources))
+	for _, source := range r.sources {
+		labels[source.ID] = source.Label
+	}
 	rendered.WriteString("path: ")
 	rendered.WriteString(strconv.Quote(explanation.Path.String()))
 	rendered.WriteByte('\n')
-	writeExplanationOrigin(&rendered, "effective source", explanation.Origin, r.sources)
+	writeExplanationOrigin(&rendered, "effective source", explanation.Origin, labels)
 	writeExplanationSnapshot(&rendered, "effective (canonical typed)", explanation.Effective, 0)
 	if explanation.SecretReference != nil {
 		rendered.WriteString("secret reference: ")
@@ -43,7 +47,7 @@ func (r *Inspection) WriteExplanation(output io.Writer, path Path) error {
 		} else {
 			rendered.WriteString("canonical typed\n")
 		}
-		writeExplanationOrigin(&rendered, "    source", change.Origin, r.sources)
+		writeExplanationOrigin(&rendered, "    source", change.Origin, labels)
 		writeExplanationSnapshot(&rendered, "    before", change.Before, 4)
 		writeExplanationSnapshot(&rendered, "    after", change.After, 4)
 		for _, reason := range change.Reasons {
@@ -65,7 +69,7 @@ func (r *Inspection) WriteExplanation(output io.Writer, path Path) error {
 	return err
 }

-func writeExplanationOrigin(output *strings.Builder, label string, origin Origin, sources []SourceInfo) {
+func writeExplanationOrigin(output *strings.Builder, label string, origin Origin, labels map[string]string) {
 	output.WriteString(label)
 	output.WriteString(": layer=")
 	output.WriteString(strconv.Quote(string(origin.Layer)))
@@ -77,7 +81,7 @@ func writeExplanationOrigin(output *strings.Builder, label string, origin Origin
 	for _, location := range origin.Locations {
 		output.WriteString("      location: source=")
 		output.WriteString(strconv.Quote(location.SourceID))
-		if label := sourceLabel(sources, location.SourceID); label != "" {
+		if label := labels[location.SourceID]; label != "" {
 			output.WriteString(" label=")
 			output.WriteString(strconv.Quote(label))
 		}
@@ -89,15 +93,6 @@ func writeExplanationOrigin(output *strings.Builder, label string, origin Origin
 	}
 }

-func sourceLabel(sources []SourceInfo, sourceID string) string {
-	for _, source := range sources {
-		if source.ID == sourceID {
-			return source.Label
-		}
-	}
-	return ""
-}
-
 func writeExplanationSnapshot(output *strings.Builder, label string, snapshot ValueSnapshot, indent int) {
 	if !snapshot.Present {
 		output.WriteString(label)
--- a/internal/engine/load_request.go
+++ b/internal/engine/load_request.go
@@ -126,6 +126,7 @@ func assembleLayeredInput[T any](request loadRequest[T], input assembledInput, a
 }

 func acquireUnderlayGroup(group loadGroup, index int, rule *VersionRule, accounting *importAccounting) (*composedDocument, []SourceInfo, map[string]ResourceContext, []Diagnostic) {
+	initialBytes, initialNodes := accounting.bytes, accounting.nodes
 	visited := make(map[resourceIdentity]importRoute)
 	hostToken := &namespaceToken{}
 	var documents []*document.Node
@@ -168,6 +169,8 @@ func acquireUnderlayGroup(group loadGroup, index int, rule *VersionRule, account
 	if len(diagnostics) != 0 {
 		return nil, sources, contexts, diagnostics
 	}
+	composition.inputBytes = accounting.bytes - initialBytes
+	composition.inputNodes = accounting.nodes - initialNodes
 	for pointer, origin := range composition.origins {
 		origin.Layer = LayerUnderlay
 		composition.origins[pointer] = origin
--- a/internal/engine/load_request_test.go
+++ b/internal/engine/load_request_test.go
@@ -208,3 +208,73 @@ func groupedErrorCode(t *testing.T, err error) Code {
 	}
 	return loadError.Diagnostics()[0].Code
 }
+
+func TestGroupedAccountingChargesMixedOccurrencesOnce(t *testing.T) {
+	const (
+		one   = "configkit: {imports: [{path: child-one.yml}]}\nleft: first\n"
+		child = "extra: imported\n"
+		two   = "configkit: {imports: [{path: child-two.yml}]}\nright: second\n"
+	)
+	filesystem := NewFilesystem("bundle", fstest.MapFS{
+		"one.yml":       &fstest.MapFile{Data: []byte(one)},
+		"child-one.yml": &fstest.MapFile{Data: []byte(child)},
+		"two.yml":       &fstest.MapFile{Data: []byte(two)},
+		"child-two.yml": &fstest.MapFile{Data: []byte(child)},
+	})
+	accounting := &importAccounting{}
+	first, sources, _, diagnostics := acquireUnderlayGroup(loadGroup{inputs: []loadInput{{source: filesystem.File("one.yml"), imports: true}}}, 1, nil, accounting)
+	if len(diagnostics) != 0 || first == nil || len(sources) != 2 || accounting.sources != 2 || accounting.bytes != int64(len(one)+len(child)) {
+		t.Fatalf("first acquisition = %#v, %#v, %#v, accounting %#v", first, sources, diagnostics, accounting)
+	}
+	second, sources, _, diagnostics := acquireUnderlayGroup(loadGroup{inputs: []loadInput{{source: filesystem.File("two.yml"), imports: true}}}, 2, nil, accounting)
+	if len(diagnostics) != 0 || second == nil || len(sources) != 2 || sources[0].ID != "source-3" || sources[1].ID != "source-4" || accounting.sources != 4 || accounting.bytes != int64(len(one)+len(two)+2*len(child)) {
+		t.Fatalf("second acquisition = %#v, %#v, %#v, accounting %#v", second, sources, diagnostics, accounting)
+	}
+	var wantNodes int
+	for _, text := range []string{one, child, two, child} {
+		parsed, diagnostics := parseSource(Bytes("fixture", []byte(text)), "source-1", defaultParseLimits())
+		if len(diagnostics) != 0 {
+			t.Fatal(diagnostics)
+		}
+		wantNodes += countInputNodes(parsed.document)
+	}
+	if accounting.nodes != wantNodes {
+		t.Fatalf("charged nodes = %d, want %d", accounting.nodes, wantNodes)
+	}
+	if first.inputBytes != int64(len(one)+len(child)) || second.inputBytes != int64(len(two)+len(child)) {
+		t.Fatalf("composition costs = %d, %d, accounting %d", first.inputBytes, second.inputBytes, accounting.bytes)
+	}
+}
+
+func TestGroupedGlobEntryBudgetIsShared(t *testing.T) {
+	filesystem := NewFilesystem("bundle", fstest.MapFS{
+		"main.yml":    &fstest.MapFile{Data: []byte("configkit: {imports: [{glob: 'parts/*.yml'}]}\n")},
+		"parts/a.yml": &fstest.MapFile{Data: []byte("left: one\n")},
+		"parts/b.yml": &fstest.MapFile{Data: []byte("right: two\n")},
+	})
+	accounting := &importAccounting{entries: maxGlobEntries - 1}
+	_, _, _, diagnostics := acquireUnderlayGroup(loadGroup{inputs: []loadInput{{source: filesystem.File("main.yml"), imports: true}}}, 1, nil, accounting)
+	if len(diagnostics) == 0 || diagnostics[0].Code != CodeImportLimitExceeded || accounting.entries <= maxGlobEntries {
+		t.Fatalf("shared glob budget = %#v, accounting %#v", diagnostics, accounting)
+	}
+}
+
+func TestGroupedMixedSourcesShareCLIRecordLimit(t *testing.T) {
+	filesystem := NewFilesystem("bundle", fstest.MapFS{"main.yml": &fstest.MapFile{Data: []byte("value: base\n")}})
+	inputs := make([]Input, maxImportSources-1)
+	inputs[0] = Input{Source: Bytes("empty-bytes", []byte("{}\n"))}
+	for index := 1; index < len(inputs); index++ {
+		inputs[index] = Input{Source: Mapping("empty-map", map[string]any{})}
+	}
+	type config struct {
+		Value string `yaml:"value"`
+	}
+	_, err := LoadLayered(Input{Source: filesystem.File("main.yml")}, testSecretBinding(), LayeredOptions[config]{
+		Underlays: []Underlay{{Inputs: inputs}},
+		Overrides: []Override{{Path: Keys("value"), Value: "cli", Flag: "--value"}},
+	})
+	loadError, ok := err.(*LoadError)
+	if !ok || len(loadError.Diagnostics()) == 0 || loadError.Diagnostics()[0].Code != CodeOverrideLimitExceeded || len(loadError.Sources()) != maxImportSources {
+		t.Fatalf("mixed source/CLI limit = %#v", err)
+	}
+}
--- a/internal/engine/underlay_bench_test.go
+++ b/internal/engine/underlay_bench_test.go
@@ -0,0 +1,156 @@
+package engine
+
+import (
+	"io"
+	"strconv"
+	"testing"
+	"testing/fstest"
+)
+
+type benchmarkCatalogConfig struct {
+	Catalog map[string]string `yaml:"catalog"`
+}
+
+type benchmarkNodeConfig struct {
+	Node string `yaml:"node"`
+}
+
+func BenchmarkUnderlayBroadCatalog(b *testing.B) {
+	for _, width := range []int{128, 256, 512} {
+		b.Run(strconv.Itoa(width), func(b *testing.B) {
+			inputs := make([]Input, 2)
+			for half := range inputs {
+				catalog := make(map[string]any, width/2)
+				for index := range width / 2 {
+					catalog["item-"+strconv.Itoa(half*width/2+index)] = "value"
+				}
+				inputs[half] = Input{Source: Mapping("catalog-"+strconv.Itoa(half), map[string]any{"catalog": catalog})}
+			}
+			options := LayeredOptions[benchmarkCatalogConfig]{Underlays: []Underlay{{Inputs: inputs}}}
+			b.ReportAllocs()
+			b.ResetTimer()
+			for range b.N {
+				if _, err := LoadLayered(Input{Source: NoSource()}, testSecretBinding(), options); err != nil {
+					b.Fatal(err)
+				}
+			}
+		})
+	}
+}
+
+func BenchmarkUnderlayManySmallTiers(b *testing.B) {
+	for _, count := range []int{32, 64, 128} {
+		b.Run(strconv.Itoa(count), func(b *testing.B) {
+			groups := make([]Underlay, count)
+			for index := range groups {
+				groups[index].Inputs = []Input{{Source: Mapping("item", map[string]any{
+					"catalog": map[string]any{"item-" + strconv.Itoa(index): "value"},
+				})}}
+			}
+			options := LayeredOptions[benchmarkCatalogConfig]{Underlays: groups}
+			b.ReportAllocs()
+			b.ResetTimer()
+			for range b.N {
+				if _, err := LoadLayered(Input{Source: NoSource()}, testSecretBinding(), options); err != nil {
+					b.Fatal(err)
+				}
+			}
+		})
+	}
+}
+
+func BenchmarkUnderlaySubtreeReplacement(b *testing.B) {
+	for _, count := range []int{32, 64, 128} {
+		b.Run(strconv.Itoa(count), func(b *testing.B) {
+			groups := make([]Underlay, count)
+			for index := range groups {
+				var node any = "temporary"
+				if index%2 == 0 {
+					node = map[string]any{"left": "one", "right": "two", "nested": map[string]any{"enabled": false}}
+				}
+				groups[index].Inputs = []Input{{Source: Mapping("replacement", map[string]any{"node": node})}}
+			}
+			options := LayeredOptions[benchmarkNodeConfig]{Underlays: groups}
+			main := Input{Source: Mapping("main", map[string]any{"node": "final"})}
+			b.ReportAllocs()
+			b.ResetTimer()
+			for range b.N {
+				if _, err := LoadLayered(main, testSecretBinding(), options); err != nil {
+					b.Fatal(err)
+				}
+			}
+		})
+	}
+}
+
+func BenchmarkUnderlayNativeImports(b *testing.B) {
+	for _, count := range []int{16, 32, 64} {
+		b.Run(strconv.Itoa(count), func(b *testing.B) {
+			files := fstest.MapFS{
+				"main.yml": &fstest.MapFile{Data: []byte("configkit: {imports: [{glob: 'defaults/*.yml'}]}\n")},
+			}
+			for index := range count {
+				name := "item-" + strconv.Itoa(index)
+				files["defaults/"+name+".yml"] = &fstest.MapFile{Data: []byte("catalog: {" + name + ": value}\n")}
+			}
+			filesystem := NewFilesystem("bundle", files)
+			main := Input{Source: filesystem.File("main.yml"), Imports: true}
+			b.ReportAllocs()
+			b.ResetTimer()
+			for range b.N {
+				if _, err := LoadLayered[benchmarkCatalogConfig](main, testSecretBinding()); err != nil {
+					b.Fatal(err)
+				}
+			}
+		})
+	}
+}
+
+func BenchmarkUnderlayRetainedHistory(b *testing.B) {
+	for _, count := range []int{16, 32, 64} {
+		b.Run(strconv.Itoa(count), func(b *testing.B) {
+			groups := make([]Underlay, count)
+			for index := range groups {
+				groups[index].Inputs = []Input{{Source: Mapping("value", map[string]any{
+					"catalog": map[string]any{"shared": strconv.Itoa(index)},
+				})}}
+			}
+			options := LayeredOptions[benchmarkCatalogConfig]{Underlays: groups}
+			b.ReportAllocs()
+			b.ResetTimer()
+			for range b.N {
+				result, err := LoadLayered(Input{Source: NoSource()}, testSecretBinding(), options)
+				if err != nil {
+					b.Fatal(err)
+				}
+				if _, ok := result.Inspection.Explain(Keys("catalog", "shared")); !ok {
+					b.Fatal("retained path was not explained")
+				}
+			}
+		})
+	}
+}
+
+func BenchmarkUnderlayRenderedHistory(b *testing.B) {
+	for _, count := range []int{32, 64, 128} {
+		b.Run(strconv.Itoa(count), func(b *testing.B) {
+			groups := make([]Underlay, count)
+			for index := range groups {
+				groups[index].Inputs = []Input{{Source: Mapping("value", map[string]any{
+					"catalog": map[string]any{"shared": strconv.Itoa(index)},
+				})}}
+			}
+			result, err := LoadLayered(Input{Source: NoSource()}, testSecretBinding(), LayeredOptions[benchmarkCatalogConfig]{Underlays: groups})
+			if err != nil {
+				b.Fatal(err)
+			}
+			b.ReportAllocs()
+			b.ResetTimer()
+			for range b.N {
+				if err := result.Inspection.WriteExplanation(io.Discard, Keys("catalog", "shared")); err != nil {
+					b.Fatal(err)
+				}
+			}
+		})
+	}
+}