up

src/Scanner/__Libraries/StellaOps.Scanner.Diff/ComponentDiffModels.cs

@@ -1,109 +1,109 @@
-using System;
-using System.Collections.Immutable;
-using System.Text.Json.Serialization;
-using StellaOps.Scanner.Core.Contracts;
-
-namespace StellaOps.Scanner.Diff;
-
-public enum ComponentChangeKind
-{
-    Added,
-    Removed,
-    VersionChanged,
-    MetadataChanged,
-}
-
-public sealed record ComponentDiffRequest
-{
-    public required ComponentGraph OldGraph { get; init; }
-
-    public required ComponentGraph NewGraph { get; init; }
-
-    public SbomView View { get; init; } = SbomView.Inventory;
-
-    public DateTimeOffset GeneratedAt { get; init; } = DateTimeOffset.UtcNow;
-
-    public string? OldImageDigest { get; init; }
-        = null;
-
-    public string? NewImageDigest { get; init; }
-        = null;
-}
-
-public sealed record ComponentChange
-{
-    [JsonPropertyName("kind")]
-    public ComponentChangeKind Kind { get; init; }
-
-    [JsonPropertyName("componentKey")]
-    public string ComponentKey { get; init; } = string.Empty;
-
-    [JsonPropertyName("introducingLayer")]
-    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
-    public string? IntroducingLayer { get; init; }
-        = null;
-
-    [JsonPropertyName("removingLayer")]
-    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
-    public string? RemovingLayer { get; init; }
-        = null;
-
-    [JsonPropertyName("oldComponent")]
-    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
-    public AggregatedComponent? OldComponent { get; init; }
-        = null;
-
-    [JsonPropertyName("newComponent")]
-    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
-    public AggregatedComponent? NewComponent { get; init; }
-        = null;
-}
-
-public sealed record LayerDiff
-{
-    [JsonPropertyName("layerDigest")]
-    public string LayerDigest { get; init; } = string.Empty;
-
-    [JsonPropertyName("changes")]
-    public ImmutableArray<ComponentChange> Changes { get; init; } = ImmutableArray<ComponentChange>.Empty;
-}
-
-public sealed record DiffSummary
-{
-    [JsonPropertyName("added")]
-    public int Added { get; init; }
-
-    [JsonPropertyName("removed")]
-    public int Removed { get; init; }
-
-    [JsonPropertyName("versionChanged")]
-    public int VersionChanged { get; init; }
-
-    [JsonPropertyName("metadataChanged")]
-    public int MetadataChanged { get; init; }
-}
-
-public sealed record ComponentDiffDocument
-{
-    [JsonPropertyName("generatedAt")]
-    public DateTimeOffset GeneratedAt { get; init; }
-
-    [JsonPropertyName("view")]
-    public SbomView View { get; init; }
-
-    [JsonPropertyName("oldImageDigest")]
-    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
-    public string? OldImageDigest { get; init; }
-        = null;
-
-    [JsonPropertyName("newImageDigest")]
-    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
-    public string? NewImageDigest { get; init; }
-        = null;
-
-    [JsonPropertyName("summary")]
-    public DiffSummary Summary { get; init; } = new();
-
-    [JsonPropertyName("layers")]
-    public ImmutableArray<LayerDiff> Layers { get; init; } = ImmutableArray<LayerDiff>.Empty;
-}
+using System;
+using System.Collections.Immutable;
+using System.Text.Json.Serialization;
+using StellaOps.Scanner.Core.Contracts;
+
+namespace StellaOps.Scanner.Diff;
+
+public enum ComponentChangeKind
+{
+    Added,
+    Removed,
+    VersionChanged,
+    MetadataChanged,
+}
+
+public sealed record ComponentDiffRequest
+{
+    public required ComponentGraph OldGraph { get; init; }
+
+    public required ComponentGraph NewGraph { get; init; }
+
+    public SbomView View { get; init; } = SbomView.Inventory;
+
+    public DateTimeOffset GeneratedAt { get; init; } = DateTimeOffset.UtcNow;
+
+    public string? OldImageDigest { get; init; }
+        = null;
+
+    public string? NewImageDigest { get; init; }
+        = null;
+}
+
+public sealed record ComponentChange
+{
+    [JsonPropertyName("kind")]
+    public ComponentChangeKind Kind { get; init; }
+
+    [JsonPropertyName("componentKey")]
+    public string ComponentKey { get; init; } = string.Empty;
+
+    [JsonPropertyName("introducingLayer")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public string? IntroducingLayer { get; init; }
+        = null;
+
+    [JsonPropertyName("removingLayer")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public string? RemovingLayer { get; init; }
+        = null;
+
+    [JsonPropertyName("oldComponent")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public AggregatedComponent? OldComponent { get; init; }
+        = null;
+
+    [JsonPropertyName("newComponent")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public AggregatedComponent? NewComponent { get; init; }
+        = null;
+}
+
+public sealed record LayerDiff
+{
+    [JsonPropertyName("layerDigest")]
+    public string LayerDigest { get; init; } = string.Empty;
+
+    [JsonPropertyName("changes")]
+    public ImmutableArray<ComponentChange> Changes { get; init; } = ImmutableArray<ComponentChange>.Empty;
+}
+
+public sealed record DiffSummary
+{
+    [JsonPropertyName("added")]
+    public int Added { get; init; }
+
+    [JsonPropertyName("removed")]
+    public int Removed { get; init; }
+
+    [JsonPropertyName("versionChanged")]
+    public int VersionChanged { get; init; }
+
+    [JsonPropertyName("metadataChanged")]
+    public int MetadataChanged { get; init; }
+}
+
+public sealed record ComponentDiffDocument
+{
+    [JsonPropertyName("generatedAt")]
+    public DateTimeOffset GeneratedAt { get; init; }
+
+    [JsonPropertyName("view")]
+    public SbomView View { get; init; }
+
+    [JsonPropertyName("oldImageDigest")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public string? OldImageDigest { get; init; }
+        = null;
+
+    [JsonPropertyName("newImageDigest")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public string? NewImageDigest { get; init; }
+        = null;
+
+    [JsonPropertyName("summary")]
+    public DiffSummary Summary { get; init; } = new();
+
+    [JsonPropertyName("layers")]
+    public ImmutableArray<LayerDiff> Layers { get; init; } = ImmutableArray<LayerDiff>.Empty;
+}

src/Scanner/__Libraries/StellaOps.Scanner.Diff/ComponentDiffer.cs

@@ -1,204 +1,204 @@
-using System;
-using System.Collections.Generic;
-using System.Collections.Immutable;
-using System.Linq;
-using StellaOps.Scanner.Core.Contracts;
-using StellaOps.Scanner.Core.Utility;
-
-namespace StellaOps.Scanner.Diff;
-
-public sealed class ComponentDiffer
-{
-    private static readonly StringComparer Ordinal = StringComparer.Ordinal;
-    private const string UnknownLayerKey = "(unknown)";
-
-    public ComponentDiffDocument Compute(ComponentDiffRequest request)
-    {
-        ArgumentNullException.ThrowIfNull(request);
-
-        var generatedAt = ScannerTimestamps.Normalize(request.GeneratedAt);
-        var oldComponents = ToDictionary(FilterComponents(request.OldGraph, request.View));
-        var newComponents = ToDictionary(FilterComponents(request.NewGraph, request.View));
-        var layerOrder = BuildLayerOrder(request.OldGraph, request.NewGraph);
-
-        var changes = new List<ComponentChange>();
-        var counters = new DiffCounters();
-
-        foreach (var (key, newComponent) in newComponents)
-        {
-            if (!oldComponents.TryGetValue(key, out var oldComponent))
-            {
-                changes.Add(new ComponentChange
-                {
-                    Kind = ComponentChangeKind.Added,
-                    ComponentKey = key,
-                    IntroducingLayer = GetIntroducingLayer(newComponent),
-                    NewComponent = newComponent,
-                });
-                counters.Added++;
-                continue;
-            }
-
-            var change = CompareComponents(oldComponent, newComponent, key);
-            if (change is not null)
-            {
-                changes.Add(change);
-                counters.Register(change.Kind);
-            }
-
-            oldComponents.Remove(key);
-        }
-
-        foreach (var (key, oldComponent) in oldComponents)
-        {
-            changes.Add(new ComponentChange
-            {
-                Kind = ComponentChangeKind.Removed,
-                ComponentKey = key,
-                RemovingLayer = GetRemovingLayer(oldComponent),
-                OldComponent = oldComponent,
-            });
-            counters.Removed++;
-        }
-
-        var layerGroups = changes
-            .GroupBy(ResolveLayerKey, Ordinal)
-            .OrderBy(group => layerOrder.TryGetValue(group.Key, out var position) ? position : int.MaxValue)
-            .ThenBy(static group => group.Key, Ordinal)
-            .Select(group => new LayerDiff
-            {
-                LayerDigest = group.Key,
-                Changes = group
-                    .OrderBy(change => change.ComponentKey, Ordinal)
-                    .ThenBy(change => change.Kind)
-                    .ThenBy(change => change.NewComponent?.Identity.Version ?? change.OldComponent?.Identity.Version ?? string.Empty, Ordinal)
-                    .ToImmutableArray(),
-            })
-            .ToImmutableArray();
-
-        var document = new ComponentDiffDocument
-        {
-            GeneratedAt = generatedAt,
-            View = request.View,
-            OldImageDigest = request.OldImageDigest,
-            NewImageDigest = request.NewImageDigest,
-            Summary = counters.ToSummary(),
-            Layers = layerGroups,
-        };
-
-        return document;
-    }
-
-    private static ComponentChange? CompareComponents(AggregatedComponent oldComponent, AggregatedComponent newComponent, string key)
-    {
-        var versionChanged = !string.Equals(oldComponent.Identity.Version, newComponent.Identity.Version, StringComparison.Ordinal);
-        if (versionChanged)
-        {
-            return new ComponentChange
-            {
-                Kind = ComponentChangeKind.VersionChanged,
-                ComponentKey = key,
-                IntroducingLayer = GetIntroducingLayer(newComponent),
-                RemovingLayer = GetRemovingLayer(oldComponent),
-                OldComponent = oldComponent,
-                NewComponent = newComponent,
-            };
-        }
-
-        var metadataChanged = HasMetadataChanged(oldComponent, newComponent);
-        if (!metadataChanged)
-        {
-            return null;
-        }
-
-        return new ComponentChange
-        {
-            Kind = ComponentChangeKind.MetadataChanged,
-            ComponentKey = key,
-            IntroducingLayer = GetIntroducingLayer(newComponent),
-            RemovingLayer = GetRemovingLayer(oldComponent),
-            OldComponent = oldComponent,
-            NewComponent = newComponent,
-        };
-    }
-
-    private static bool HasMetadataChanged(AggregatedComponent oldComponent, AggregatedComponent newComponent)
-    {
-        if (!string.Equals(oldComponent.Identity.Name, newComponent.Identity.Name, StringComparison.Ordinal))
-        {
-            return true;
-        }
-
-        if (!string.Equals(oldComponent.Identity.ComponentType, newComponent.Identity.ComponentType, StringComparison.Ordinal))
-        {
-            return true;
-        }
-
-        if (!string.Equals(oldComponent.Identity.Group, newComponent.Identity.Group, StringComparison.Ordinal))
-        {
-            return true;
-        }
-
-        if (!string.Equals(oldComponent.Identity.Purl, newComponent.Identity.Purl, StringComparison.Ordinal))
-        {
-            return true;
-        }
-
-        if (!oldComponent.Dependencies.SequenceEqual(newComponent.Dependencies, Ordinal))
-        {
-            return true;
-        }
-
-        if (!oldComponent.LayerDigests.SequenceEqual(newComponent.LayerDigests, Ordinal))
-        {
-            return true;
-        }
-
-        if (!oldComponent.Evidence.SequenceEqual(newComponent.Evidence))
-        {
-            return true;
-        }
-
-        if (UsageChanged(oldComponent.Usage, newComponent.Usage))
-        {
-            return true;
-        }
-
-        if (!MetadataEquals(oldComponent.Metadata, newComponent.Metadata))
-        {
-            return true;
-        }
-
-        return false;
-    }
-
-    private static bool UsageChanged(ComponentUsage oldUsage, ComponentUsage newUsage)
-    {
-        if (oldUsage.UsedByEntrypoint != newUsage.UsedByEntrypoint)
-        {
-            return true;
-        }
-
-        return !oldUsage.Entrypoints.SequenceEqual(newUsage.Entrypoints, Ordinal);
-    }
-
-    private static bool MetadataEquals(ComponentMetadata? left, ComponentMetadata? right)
-    {
-        if (left is null && right is null)
-        {
-            return true;
-        }
-
-        if (left is null || right is null)
-        {
-            return false;
-        }
-
-        if (!string.Equals(left.Scope, right.Scope, StringComparison.Ordinal))
-        {
-            return false;
-        }
-
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Linq;
+using StellaOps.Scanner.Core.Contracts;
+using StellaOps.Scanner.Core.Utility;
+
+namespace StellaOps.Scanner.Diff;
+
+public sealed class ComponentDiffer
+{
+    private static readonly StringComparer Ordinal = StringComparer.Ordinal;
+    private const string UnknownLayerKey = "(unknown)";
+
+    public ComponentDiffDocument Compute(ComponentDiffRequest request)
+    {
+        ArgumentNullException.ThrowIfNull(request);
+
+        var generatedAt = ScannerTimestamps.Normalize(request.GeneratedAt);
+        var oldComponents = ToDictionary(FilterComponents(request.OldGraph, request.View));
+        var newComponents = ToDictionary(FilterComponents(request.NewGraph, request.View));
+        var layerOrder = BuildLayerOrder(request.OldGraph, request.NewGraph);
+
+        var changes = new List<ComponentChange>();
+        var counters = new DiffCounters();
+
+        foreach (var (key, newComponent) in newComponents)
+        {
+            if (!oldComponents.TryGetValue(key, out var oldComponent))
+            {
+                changes.Add(new ComponentChange
+                {
+                    Kind = ComponentChangeKind.Added,
+                    ComponentKey = key,
+                    IntroducingLayer = GetIntroducingLayer(newComponent),
+                    NewComponent = newComponent,
+                });
+                counters.Added++;
+                continue;
+            }
+
+            var change = CompareComponents(oldComponent, newComponent, key);
+            if (change is not null)
+            {
+                changes.Add(change);
+                counters.Register(change.Kind);
+            }
+
+            oldComponents.Remove(key);
+        }
+
+        foreach (var (key, oldComponent) in oldComponents)
+        {
+            changes.Add(new ComponentChange
+            {
+                Kind = ComponentChangeKind.Removed,
+                ComponentKey = key,
+                RemovingLayer = GetRemovingLayer(oldComponent),
+                OldComponent = oldComponent,
+            });
+            counters.Removed++;
+        }
+
+        var layerGroups = changes
+            .GroupBy(ResolveLayerKey, Ordinal)
+            .OrderBy(group => layerOrder.TryGetValue(group.Key, out var position) ? position : int.MaxValue)
+            .ThenBy(static group => group.Key, Ordinal)
+            .Select(group => new LayerDiff
+            {
+                LayerDigest = group.Key,
+                Changes = group
+                    .OrderBy(change => change.ComponentKey, Ordinal)
+                    .ThenBy(change => change.Kind)
+                    .ThenBy(change => change.NewComponent?.Identity.Version ?? change.OldComponent?.Identity.Version ?? string.Empty, Ordinal)
+                    .ToImmutableArray(),
+            })
+            .ToImmutableArray();
+
+        var document = new ComponentDiffDocument
+        {
+            GeneratedAt = generatedAt,
+            View = request.View,
+            OldImageDigest = request.OldImageDigest,
+            NewImageDigest = request.NewImageDigest,
+            Summary = counters.ToSummary(),
+            Layers = layerGroups,
+        };
+
+        return document;
+    }
+
+    private static ComponentChange? CompareComponents(AggregatedComponent oldComponent, AggregatedComponent newComponent, string key)
+    {
+        var versionChanged = !string.Equals(oldComponent.Identity.Version, newComponent.Identity.Version, StringComparison.Ordinal);
+        if (versionChanged)
+        {
+            return new ComponentChange
+            {
+                Kind = ComponentChangeKind.VersionChanged,
+                ComponentKey = key,
+                IntroducingLayer = GetIntroducingLayer(newComponent),
+                RemovingLayer = GetRemovingLayer(oldComponent),
+                OldComponent = oldComponent,
+                NewComponent = newComponent,
+            };
+        }
+
+        var metadataChanged = HasMetadataChanged(oldComponent, newComponent);
+        if (!metadataChanged)
+        {
+            return null;
+        }
+
+        return new ComponentChange
+        {
+            Kind = ComponentChangeKind.MetadataChanged,
+            ComponentKey = key,
+            IntroducingLayer = GetIntroducingLayer(newComponent),
+            RemovingLayer = GetRemovingLayer(oldComponent),
+            OldComponent = oldComponent,
+            NewComponent = newComponent,
+        };
+    }
+
+    private static bool HasMetadataChanged(AggregatedComponent oldComponent, AggregatedComponent newComponent)
+    {
+        if (!string.Equals(oldComponent.Identity.Name, newComponent.Identity.Name, StringComparison.Ordinal))
+        {
+            return true;
+        }
+
+        if (!string.Equals(oldComponent.Identity.ComponentType, newComponent.Identity.ComponentType, StringComparison.Ordinal))
+        {
+            return true;
+        }
+
+        if (!string.Equals(oldComponent.Identity.Group, newComponent.Identity.Group, StringComparison.Ordinal))
+        {
+            return true;
+        }
+
+        if (!string.Equals(oldComponent.Identity.Purl, newComponent.Identity.Purl, StringComparison.Ordinal))
+        {
+            return true;
+        }
+
+        if (!oldComponent.Dependencies.SequenceEqual(newComponent.Dependencies, Ordinal))
+        {
+            return true;
+        }
+
+        if (!oldComponent.LayerDigests.SequenceEqual(newComponent.LayerDigests, Ordinal))
+        {
+            return true;
+        }
+
+        if (!oldComponent.Evidence.SequenceEqual(newComponent.Evidence))
+        {
+            return true;
+        }
+
+        if (UsageChanged(oldComponent.Usage, newComponent.Usage))
+        {
+            return true;
+        }
+
+        if (!MetadataEquals(oldComponent.Metadata, newComponent.Metadata))
+        {
+            return true;
+        }
+
+        return false;
+    }
+
+    private static bool UsageChanged(ComponentUsage oldUsage, ComponentUsage newUsage)
+    {
+        if (oldUsage.UsedByEntrypoint != newUsage.UsedByEntrypoint)
+        {
+            return true;
+        }
+
+        return !oldUsage.Entrypoints.SequenceEqual(newUsage.Entrypoints, Ordinal);
+    }
+
+    private static bool MetadataEquals(ComponentMetadata? left, ComponentMetadata? right)
+    {
+        if (left is null && right is null)
+        {
+            return true;
+        }
+
+        if (left is null || right is null)
+        {
+            return false;
+        }
+
+        if (!string.Equals(left.Scope, right.Scope, StringComparison.Ordinal))
+        {
+            return false;
+        }
+
         if (!SequenceEqual(left.Licenses, right.Licenses))
         {
             return false;
@@ -214,67 +214,67 @@ public sealed class ComponentDiffer
             return false;
         }
 
-        return true;
-    }
-
-    private static bool SequenceEqual(IReadOnlyList<string>? left, IReadOnlyList<string>? right)
-    {
-        if (left is null && right is null)
-        {
-            return true;
-        }
-
-        if (left is null || right is null)
-        {
-            return false;
-        }
-
-        if (left.Count != right.Count)
-        {
-            return false;
-        }
-
-        for (var i = 0; i < left.Count; i++)
-        {
-            if (!string.Equals(left[i], right[i], StringComparison.Ordinal))
-            {
-                return false;
-            }
-        }
-
-        return true;
-    }
-
-    private static bool DictionaryEqual(IReadOnlyDictionary<string, string>? left, IReadOnlyDictionary<string, string>? right)
-    {
-        if (left is null && right is null)
-        {
-            return true;
-        }
-
-        if (left is null || right is null)
-        {
-            return false;
-        }
-
-        if (left.Count != right.Count)
-        {
-            return false;
-        }
-
-        foreach (var (key, value) in left)
-        {
-            if (!right.TryGetValue(key, out var rightValue))
-            {
-                return false;
-            }
-
-            if (!string.Equals(value, rightValue, StringComparison.Ordinal))
-            {
-                return false;
-            }
-        }
-
+        return true;
+    }
+
+    private static bool SequenceEqual(IReadOnlyList<string>? left, IReadOnlyList<string>? right)
+    {
+        if (left is null && right is null)
+        {
+            return true;
+        }
+
+        if (left is null || right is null)
+        {
+            return false;
+        }
+
+        if (left.Count != right.Count)
+        {
+            return false;
+        }
+
+        for (var i = 0; i < left.Count; i++)
+        {
+            if (!string.Equals(left[i], right[i], StringComparison.Ordinal))
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    private static bool DictionaryEqual(IReadOnlyDictionary<string, string>? left, IReadOnlyDictionary<string, string>? right)
+    {
+        if (left is null && right is null)
+        {
+            return true;
+        }
+
+        if (left is null || right is null)
+        {
+            return false;
+        }
+
+        if (left.Count != right.Count)
+        {
+            return false;
+        }
+
+        foreach (var (key, value) in left)
+        {
+            if (!right.TryGetValue(key, out var rightValue))
+            {
+                return false;
+            }
+
+            if (!string.Equals(value, rightValue, StringComparison.Ordinal))
+            {
+                return false;
+            }
+        }
+
         return true;
     }
 
@@ -299,100 +299,100 @@ public sealed class ComponentDiffer
         var dictionary = new Dictionary<string, AggregatedComponent>(components.Length, Ordinal);
         foreach (var component in components)
         {
-            dictionary[component.Identity.Key] = component;
-        }
-
-        return dictionary;
-    }
-
-    private static ImmutableArray<AggregatedComponent> FilterComponents(ComponentGraph graph, SbomView view)
-    {
-        if (view == SbomView.Usage)
-        {
-            return graph.Components.Where(static component => component.Usage.UsedByEntrypoint).ToImmutableArray();
-        }
-
-        return graph.Components;
-    }
-
-    private static Dictionary<string, int> BuildLayerOrder(ComponentGraph oldGraph, ComponentGraph newGraph)
-    {
-        var order = new Dictionary<string, int>(Ordinal);
-        var index = 0;
-
-        foreach (var layer in newGraph.Layers)
-        {
-            AddLayer(order, layer.LayerDigest, ref index);
-        }
-
-        foreach (var layer in oldGraph.Layers)
-        {
-            AddLayer(order, layer.LayerDigest, ref index);
-        }
-
-        return order;
-    }
-
-    private static void AddLayer(IDictionary<string, int> order, string? layerDigest, ref int index)
-    {
-        var normalized = NormalizeLayer(layerDigest);
-        if (normalized is null || order.ContainsKey(normalized))
-        {
-            return;
-        }
-
-        order[normalized] = index++;
-    }
-
-    private static string ResolveLayerKey(ComponentChange change)
-        => NormalizeLayer(change.IntroducingLayer) ?? NormalizeLayer(change.RemovingLayer) ?? UnknownLayerKey;
-
-    private static string? GetIntroducingLayer(AggregatedComponent component)
-        => NormalizeLayer(component.FirstLayerDigest);
-
-    private static string? GetRemovingLayer(AggregatedComponent component)
-    {
-        var layer = component.LastLayerDigest ?? component.FirstLayerDigest;
-        return NormalizeLayer(layer);
-    }
-
-    private static string? NormalizeLayer(string? layer)
-    {
-        if (string.IsNullOrWhiteSpace(layer))
-        {
-            return null;
-        }
-
-        return layer;
-    }
-
-    private sealed class DiffCounters
-    {
-        public int Added;
-        public int Removed;
-        public int VersionChanged;
-        public int MetadataChanged;
-
-        public void Register(ComponentChangeKind kind)
-        {
-            switch (kind)
-            {
-                case ComponentChangeKind.VersionChanged:
-                    VersionChanged++;
-                    break;
-                case ComponentChangeKind.MetadataChanged:
-                    MetadataChanged++;
-                    break;
-            }
-        }
-
-        public DiffSummary ToSummary()
-            => new()
-            {
-                Added = Added,
-                Removed = Removed,
-                VersionChanged = VersionChanged,
-                MetadataChanged = MetadataChanged,
-            };
-    }
-}
+            dictionary[component.Identity.Key] = component;
+        }
+
+        return dictionary;
+    }
+
+    private static ImmutableArray<AggregatedComponent> FilterComponents(ComponentGraph graph, SbomView view)
+    {
+        if (view == SbomView.Usage)
+        {
+            return graph.Components.Where(static component => component.Usage.UsedByEntrypoint).ToImmutableArray();
+        }
+
+        return graph.Components;
+    }
+
+    private static Dictionary<string, int> BuildLayerOrder(ComponentGraph oldGraph, ComponentGraph newGraph)
+    {
+        var order = new Dictionary<string, int>(Ordinal);
+        var index = 0;
+
+        foreach (var layer in newGraph.Layers)
+        {
+            AddLayer(order, layer.LayerDigest, ref index);
+        }
+
+        foreach (var layer in oldGraph.Layers)
+        {
+            AddLayer(order, layer.LayerDigest, ref index);
+        }
+
+        return order;
+    }
+
+    private static void AddLayer(IDictionary<string, int> order, string? layerDigest, ref int index)
+    {
+        var normalized = NormalizeLayer(layerDigest);
+        if (normalized is null || order.ContainsKey(normalized))
+        {
+            return;
+        }
+
+        order[normalized] = index++;
+    }
+
+    private static string ResolveLayerKey(ComponentChange change)
+        => NormalizeLayer(change.IntroducingLayer) ?? NormalizeLayer(change.RemovingLayer) ?? UnknownLayerKey;
+
+    private static string? GetIntroducingLayer(AggregatedComponent component)
+        => NormalizeLayer(component.FirstLayerDigest);
+
+    private static string? GetRemovingLayer(AggregatedComponent component)
+    {
+        var layer = component.LastLayerDigest ?? component.FirstLayerDigest;
+        return NormalizeLayer(layer);
+    }
+
+    private static string? NormalizeLayer(string? layer)
+    {
+        if (string.IsNullOrWhiteSpace(layer))
+        {
+            return null;
+        }
+
+        return layer;
+    }
+
+    private sealed class DiffCounters
+    {
+        public int Added;
+        public int Removed;
+        public int VersionChanged;
+        public int MetadataChanged;
+
+        public void Register(ComponentChangeKind kind)
+        {
+            switch (kind)
+            {
+                case ComponentChangeKind.VersionChanged:
+                    VersionChanged++;
+                    break;
+                case ComponentChangeKind.MetadataChanged:
+                    MetadataChanged++;
+                    break;
+            }
+        }
+
+        public DiffSummary ToSummary()
+            => new()
+            {
+                Added = Added,
+                Removed = Removed,
+                VersionChanged = VersionChanged,
+                MetadataChanged = MetadataChanged,
+            };
+    }
+}

src/Scanner/__Libraries/StellaOps.Scanner.Diff/DiffJsonSerializer.cs

@@ -1,10 +1,10 @@
-using System.Text.Json;
-using StellaOps.Scanner.Core.Serialization;
-
-namespace StellaOps.Scanner.Diff;
-
-public static class DiffJsonSerializer
-{
-    public static string Serialize(ComponentDiffDocument document)
-        => JsonSerializer.Serialize(document, ScannerJsonOptions.Default);
-}
+using System.Text.Json;
+using StellaOps.Scanner.Core.Serialization;
+
+namespace StellaOps.Scanner.Diff;
+
+public static class DiffJsonSerializer
+{
+    public static string Serialize(ComponentDiffDocument document)
+        => JsonSerializer.Serialize(document, ScannerJsonOptions.Default);
+}