diff --git a/DesignPatterns.SourceGenerators/Generators/CompositePartGenerator.cs b/DesignPatterns.SourceGenerators/Generators/CompositePartGenerator.cs
index 5a0846a..1036688 100644
--- a/DesignPatterns.SourceGenerators/Generators/CompositePartGenerator.cs
+++ b/DesignPatterns.SourceGenerators/Generators/CompositePartGenerator.cs
@@ -142,7 +142,7 @@ private static Result<CompositeRegistration> Transform(GeneratorAttributeSyntaxC
                 ImplementsContract(implementation, contract),
                 HasPublicParameterlessConstructor(implementation),
                 ImplementsBuildable(implementation, contract),
-                context.TargetNode.GetLocation()));
+                new LocationInfo(context.TargetNode.GetLocation())));
         }
 
         return Result<CompositeRegistration>.Empty;
@@ -202,7 +202,7 @@ private static void ReportDuplicateKeys(SourceProductionContext context, List<Co
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DuplicateKeyDescriptor,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.Key,
                     contractName));
             }
@@ -220,7 +220,7 @@ private static void ReportUnknownParentKeys(SourceProductionContext context, Lis
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 UnknownParentKeyDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.ParentKey!,
                 contractName));
         }
@@ -235,7 +235,7 @@ private static void ReportCycles(SourceProductionContext context, List<Composite
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 CycleDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.Key,
                 contractName));
         }
@@ -247,7 +247,7 @@ private static void ReportContractMismatches(SourceProductionContext context, Li
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 ContractMismatchDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.ImplementationName,
                 registration.Contract.FullyQualifiedName));
         }
@@ -259,7 +259,7 @@ private static void ReportMissingConstructors(SourceProductionContext context, L
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 MissingParameterlessConstructorDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.ImplementationName));
         }
     }
@@ -273,7 +273,7 @@ private static void ReportMissingBuildable(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 MissingBuildableDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.ImplementationName,
                 contract.FullyQualifiedName));
         }
@@ -446,5 +446,5 @@ private sealed record CompositeRegistration(
         bool ImplementsContract,
         bool HasPublicParameterlessConstructor,
         bool ImplementsBuildable,
-        Location Location);
+        LocationInfo Location);
 }
diff --git a/DesignPatterns.SourceGenerators/Generators/DecoratorGenerator.cs b/DesignPatterns.SourceGenerators/Generators/DecoratorGenerator.cs
index 46b04dc..cf14f36 100644
--- a/DesignPatterns.SourceGenerators/Generators/DecoratorGenerator.cs
+++ b/DesignPatterns.SourceGenerators/Generators/DecoratorGenerator.cs
@@ -126,7 +126,7 @@ private static Result<DecoratorRegistration> Transform(GeneratorAttributeSyntaxC
                 ImplementsAsyncDecoratorInterface(decoratorType, serviceType),
                 HasValidAsyncSignature(decoratorType, serviceType),
                 HasPublicParameterlessConstructor(decoratorType),
-                context.TargetNode.GetLocation()));
+                new LocationInfo(context.TargetNode.GetLocation())));
         }
 
         return Result<DecoratorRegistration>.Empty;
@@ -186,7 +186,7 @@ private static void ReportValidationDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DuplicateOrderDescriptor,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.Order,
                     serviceName));
             }
@@ -196,7 +196,7 @@ private static void ReportValidationDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 ContractMismatchDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.DecoratorName,
                 registration.Service.FullyQualifiedName));
         }
@@ -205,7 +205,7 @@ private static void ReportValidationDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 MissingDecoratorInterfaceDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.DecoratorName,
                 registration.Service.FullyQualifiedName));
         }
@@ -214,7 +214,7 @@ private static void ReportValidationDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 AsyncSignatureMismatchDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.DecoratorName,
                 registration.Service.FullyQualifiedName));
         }
@@ -225,14 +225,14 @@ private static void ReportValidationDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DiNotResolvableDescriptor,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.DecoratorName));
             }
             else
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     MissingParameterlessConstructorDescriptor,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.DecoratorName));
             }
         }
@@ -398,5 +398,5 @@ private sealed record DecoratorRegistration(
         bool ImplementsAsyncDecoratorInterface,
         bool HasValidAsyncSignature,
         bool HasPublicParameterlessConstructor,
-        Location Location);
+        LocationInfo Location);
 }
diff --git a/DesignPatterns.SourceGenerators/Generators/GenerateSingletonGenerator.cs b/DesignPatterns.SourceGenerators/Generators/GenerateSingletonGenerator.cs
index 4b68138..a70ca88 100644
--- a/DesignPatterns.SourceGenerators/Generators/GenerateSingletonGenerator.cs
+++ b/DesignPatterns.SourceGenerators/Generators/GenerateSingletonGenerator.cs
@@ -63,7 +63,7 @@ private static Result<SingletonTargetInfo> GetTargetInfo(GeneratorAttributeSynta
             }
         }
 
-        var location = classDeclaration.GetLocation();
+        var location = new LocationInfo(classDeclaration.GetLocation());
         var className = symbol.Name;
         var isStatic = symbol.IsStatic;
         var typeKind = symbol.TypeKind;
@@ -110,7 +110,7 @@ private static void Execute(SourceProductionContext context, Result<SingletonTar
     }
 
     private sealed record SingletonTargetInfo(
-        Location Location,
+        LocationInfo Location,
         string ClassName,
         string? NamespaceName,
         bool ThreadSafe,
diff --git a/DesignPatterns.SourceGenerators/Generators/HandlerOrderGenerator.cs b/DesignPatterns.SourceGenerators/Generators/HandlerOrderGenerator.cs
index b677be1..6f66a2c 100644
--- a/DesignPatterns.SourceGenerators/Generators/HandlerOrderGenerator.cs
+++ b/DesignPatterns.SourceGenerators/Generators/HandlerOrderGenerator.cs
@@ -61,21 +61,21 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
                 source.Right));
     }
 
-    private static List<HandlerRegistration> Transform(GeneratorAttributeSyntaxContext context, bool isGenericAttribute)
+    private static EquatableArray<HandlerRegistration> Transform(GeneratorAttributeSyntaxContext context, bool isGenericAttribute)
     {
         var result = new List<HandlerRegistration>();
 
         if (context.TargetSymbol is not INamedTypeSymbol handlerType)
         {
-            return result;
+            return new EquatableArray<HandlerRegistration>(result.ToArray());
         }
 
         if (context.Attributes.IsDefaultOrEmpty)
         {
-            return result;
+            return new EquatableArray<HandlerRegistration>(result.ToArray());
         }
 
-        var location = context.TargetNode.GetLocation();
+        var location = new LocationInfo(context.TargetNode.GetLocation());
         var handlerName = handlerType.Name;
         var handlerFullyQualifiedDisplayString = handlerType.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat);
 
@@ -147,7 +147,7 @@ private static List<HandlerRegistration> Transform(GeneratorAttributeSyntaxConte
                 location));
         }
 
-        return result;
+        return new EquatableArray<HandlerRegistration>(result.ToArray());
     }
 
     private static void Execute(
@@ -218,7 +218,7 @@ private static void ReportValidationDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DuplicateOrderDescriptor,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.Order,
                     contextName));
             }
@@ -228,7 +228,7 @@ private static void ReportValidationDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 HandlerContractMismatchDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.HandlerName,
                 registration.Context.FullyQualifiedName));
         }
@@ -237,7 +237,7 @@ private static void ReportValidationDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 MissingParameterlessConstructorDescriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.HandlerName));
         }
 
@@ -262,7 +262,7 @@ private static void ReportGuardDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.HandlerOrderGuardMethodNotFound,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     guard.Name,
                     registration.HandlerName,
                     contextTypeDisplay));
@@ -273,7 +273,7 @@ private static void ReportGuardDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.HandlerOrderGuardMethodNotStatic,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     guard.Name,
                     registration.HandlerName));
                 continue;
@@ -283,7 +283,7 @@ private static void ReportGuardDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.HandlerOrderGuardMethodWrongSignature,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     guard.Name,
                     registration.HandlerName,
                     contextTypeDisplay));
@@ -346,5 +346,5 @@ private sealed record HandlerRegistration(
         bool ImplementsHandler,
         bool HasPublicParameterlessConstructor,
         GuardResolution Guard,
-        Location Location);
+        LocationInfo Location);
 }
diff --git a/DesignPatterns.SourceGenerators/Generators/LocationInfo.cs b/DesignPatterns.SourceGenerators/Generators/LocationInfo.cs
new file mode 100644
index 0000000..32180e4
--- /dev/null
+++ b/DesignPatterns.SourceGenerators/Generators/LocationInfo.cs
@@ -0,0 +1,74 @@
+using System;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Text;
+
+namespace DesignPatterns.SourceGenerators.Generators;
+
+/// <summary>
+/// A value-equatable representation of a <see cref="Location"/>. Used in
+/// incremental generator models to ensure correct caching by the Roslyn
+/// incremental pipeline — <see cref="Location"/> uses reference equality,
+/// which breaks model value equality when <see cref="Compilation.Clone"/>
+/// creates new <see cref="Location"/> objects.
+/// </summary>
+internal readonly struct LocationInfo : IEquatable<LocationInfo>
+{
+    public string? FilePath { get; }
+    public TextSpan TextSpan { get; }
+    public LinePositionSpan LineSpan { get; }
+
+    public LocationInfo(Location? location)
+    {
+        if (location is null)
+        {
+            FilePath = null;
+            TextSpan = default;
+            LineSpan = default;
+            return;
+        }
+
+        var lineSpan = location.GetLineSpan();
+        FilePath = location.SourceTree?.FilePath ?? lineSpan.Path;
+        TextSpan = location.SourceSpan;
+        LineSpan = lineSpan.Span;
+    }
+
+    /// <summary>
+    /// Reconstructs a <see cref="Location"/> suitable for diagnostic reporting.
+    /// The returned location is an <see cref="ExternalFileLocation"/> that does
+    /// not reference a <see cref="SyntaxTree"/>, which is sufficient for
+    /// <see cref="Diagnostic.Create(DiagnosticDescriptor, Location, object[])"/>.
+    /// </summary>
+    public Location? ToLocation()
+    {
+        if (FilePath is null)
+        {
+            return null;
+        }
+
+        return Location.Create(FilePath, TextSpan, LineSpan);
+    }
+
+    public bool Equals(LocationInfo other)
+    {
+        return string.Equals(FilePath, other.FilePath, StringComparison.Ordinal)
+            && TextSpan == other.TextSpan
+            && LineSpan == other.LineSpan;
+    }
+
+    public override bool Equals(object? obj) => obj is LocationInfo other && Equals(other);
+
+    public override int GetHashCode()
+    {
+        unchecked
+        {
+            return (StringComparer.Ordinal.GetHashCode(FilePath ?? string.Empty) * 397)
+                ^ TextSpan.GetHashCode()
+                ^ LineSpan.GetHashCode();
+        }
+    }
+
+    public static bool operator ==(LocationInfo left, LocationInfo right) => left.Equals(right);
+
+    public static bool operator !=(LocationInfo left, LocationInfo right) => !left.Equals(right);
+}
diff --git a/DesignPatterns.SourceGenerators/Generators/RegisterEventHandlerGenerator.cs b/DesignPatterns.SourceGenerators/Generators/RegisterEventHandlerGenerator.cs
index 1f81bee..b74501b 100644
--- a/DesignPatterns.SourceGenerators/Generators/RegisterEventHandlerGenerator.cs
+++ b/DesignPatterns.SourceGenerators/Generators/RegisterEventHandlerGenerator.cs
@@ -33,7 +33,7 @@ internal sealed record EventHandlerRegistration(
     string HandlerFullyQualifiedDisplayString,
     bool ImplementsHandlerInterface,
     bool HasPublicParameterlessConstructor,
-    Location Location);
+    LocationInfo Location);
 
 /// <summary>
 /// Generates <c>{Event}EventHandlerRegistry</c> static classes for
@@ -122,7 +122,7 @@ private static List<EventHandlerRegistration> Transform(
                     : eventType.ContainingNamespace.ToDisplayString(),
                 eventType.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat));
 
-            var location = context.TargetNode.GetLocation();
+            var location = new LocationInfo(context.TargetNode.GetLocation());
             result.Add(new EventHandlerRegistration(
                 eventInfo,
                 handler.Name,
@@ -152,7 +152,7 @@ private static void Execute(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 DesignPatternsDiagnosticDescriptors.RegisterEventHandlerContractMismatch,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.HandlerName,
                 registration.Event.FullyQualifiedName));
         }
@@ -169,7 +169,7 @@ private static void Execute(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.RegisterEventHandlerDuplicateOnSameClass,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.HandlerName,
                     registration.Event.FullyQualifiedName));
             }
diff --git a/DesignPatterns.SourceGenerators/Generators/RegistrationGeneratorHelper.cs b/DesignPatterns.SourceGenerators/Generators/RegistrationGeneratorHelper.cs
index 86672d8..27ad369 100644
--- a/DesignPatterns.SourceGenerators/Generators/RegistrationGeneratorHelper.cs
+++ b/DesignPatterns.SourceGenerators/Generators/RegistrationGeneratorHelper.cs
@@ -33,11 +33,11 @@ internal sealed record KeyedRegistration(
     bool IsAsync,
     bool ImplementsAsyncFactory,
     int PoolSize,
-    Location Location);
+    LocationInfo Location);
 
 internal static class RegistrationGeneratorHelper
 {
-    internal static List<KeyedRegistration> Transform(
+    internal static EquatableArray<KeyedRegistration> Transform(
         GeneratorAttributeSyntaxContext context,
         bool isGenericAttribute)
     {
@@ -45,7 +45,7 @@ internal static List<KeyedRegistration> Transform(
 
         if (context.TargetSymbol is not INamedTypeSymbol implementation)
         {
-            return result;
+            return new EquatableArray<KeyedRegistration>(result.ToArray());
         }
 
         foreach (var attribute in context.Attributes)
@@ -85,7 +85,7 @@ internal static List<KeyedRegistration> Transform(
                     : contract.ContainingNamespace.ToDisplayString(),
                 contract.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat));
 
-            var location = context.TargetNode.GetLocation();
+            var location = new LocationInfo(context.TargetNode.GetLocation());
 
             // Resolve optional Guard property from the attribute.
             string? guardName = null;
@@ -134,7 +134,7 @@ internal static List<KeyedRegistration> Transform(
                 location));
         }
 
-        return result;
+        return new EquatableArray<KeyedRegistration>(result.ToArray());
     }
 
     internal static void Execute(
@@ -210,7 +210,7 @@ private static void ReportDuplicateKeys(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     descriptor,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.Key,
                     contractName));
             }
@@ -226,7 +226,7 @@ private static void ReportContractMismatches(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 descriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.ImplementationName,
                 registration.Contract.FullyQualifiedName));
         }
@@ -241,7 +241,7 @@ private static void ReportMissingConstructors(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 descriptor,
-                registration.Location,
+                registration.Location.ToLocation(),
                 registration.ImplementationName));
         }
     }
@@ -264,7 +264,7 @@ private static void ReportGuardDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StrategyGuardMethodNotFound,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     guard.Name,
                     registration.ImplementationName,
                     keyTypeDisplay));
@@ -275,7 +275,7 @@ private static void ReportGuardDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StrategyGuardMethodNotStatic,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     guard.Name,
                     registration.ImplementationName));
                 continue;
@@ -285,7 +285,7 @@ private static void ReportGuardDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StrategyGuardMethodWrongSignature,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     guard.Name,
                     registration.ImplementationName,
                     keyTypeDisplay));
@@ -306,7 +306,7 @@ private static void ReportFactoryAsyncDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.FactoryAsyncSignatureMismatch,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.ImplementationName,
                     registration.Contract.FullyQualifiedName));
             }
@@ -316,7 +316,7 @@ private static void ReportFactoryAsyncDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.FactoryPoolSizeInvalid,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.ImplementationName,
                     registration.PoolSize));
             }
@@ -326,7 +326,7 @@ private static void ReportFactoryAsyncDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.FactoryPoolSizeTooLarge,
-                    registration.Location,
+                    registration.Location.ToLocation(),
                     registration.ImplementationName,
                     registration.PoolSize));
             }
diff --git a/DesignPatterns.SourceGenerators/Generators/Result.cs b/DesignPatterns.SourceGenerators/Generators/Result.cs
index 8ee7564..f164528 100644
--- a/DesignPatterns.SourceGenerators/Generators/Result.cs
+++ b/DesignPatterns.SourceGenerators/Generators/Result.cs
@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Runtime.CompilerServices;
 using Microsoft.CodeAnalysis;
 
 namespace DesignPatterns.SourceGenerators.Generators;
@@ -17,7 +16,7 @@ namespace DesignPatterns.SourceGenerators.Generators;
     public DiagnosticDescriptor Descriptor { get; }
 
     /// <summary>Location where the diagnostic should be reported (may be null).</summary>
-    public Location? Location { get; }
+    public LocationInfo? Location { get; }
 
     /// <summary>Message arguments passed to <c>Diagnostic.Create</c>.</summary>
     public object?[] MessageArgs { get; }
@@ -26,7 +25,7 @@ namespace DesignPatterns.SourceGenerators.Generators;
     /// Creates a <see cref="DiagnosticInfo"/> from a descriptor, optional
     /// location, and message arguments.
     /// </summary>
-    public DiagnosticInfo(DiagnosticDescriptor descriptor, Location? location, params object?[] messageArgs)
+    public DiagnosticInfo(DiagnosticDescriptor descriptor, LocationInfo? location, params object?[] messageArgs)
     {
         Descriptor = descriptor;
         Location = location;
@@ -34,12 +33,12 @@ public DiagnosticInfo(DiagnosticDescriptor descriptor, Location? location, param
     }
 
     /// <summary>Reconstructs the <see cref="Diagnostic"/> for reporting.</summary>
-    public Diagnostic ToDiagnostic() => Diagnostic.Create(Descriptor, Location, MessageArgs)!;
+    public Diagnostic ToDiagnostic() => Diagnostic.Create(Descriptor, Location?.ToLocation(), MessageArgs)!;
 
     /// <inheritdoc />
     public bool Equals(DiagnosticInfo other) =>
         string.Equals(Descriptor.Id, other.Descriptor.Id, StringComparison.Ordinal)
-        && ReferenceEquals(Location, other.Location)
+        && Location == other.Location
         && MessageArgsEqual(other.MessageArgs);
 
     /// <inheritdoc />
@@ -49,7 +48,7 @@ public bool Equals(DiagnosticInfo other) =>
     public override int GetHashCode()
     {
         var hash = Descriptor.Id?.GetHashCode() ?? 0;
-        hash = (hash * 31) + (Location is null ? 0 : RuntimeHelpers.GetHashCode(Location));
+        hash = (hash * 31) + (Location?.GetHashCode() ?? 0);
         foreach (var messageArg in MessageArgs ?? Array.Empty<object?>())
         {
             hash = (hash * 31) + EqualityComparer<object?>.Default.GetHashCode(messageArg);
diff --git a/DesignPatterns.SourceGenerators/Generators/StateTransition/StateTransitionModels.cs b/DesignPatterns.SourceGenerators/Generators/StateTransition/StateTransitionModels.cs
index 406368e..468823d 100644
--- a/DesignPatterns.SourceGenerators/Generators/StateTransition/StateTransitionModels.cs
+++ b/DesignPatterns.SourceGenerators/Generators/StateTransition/StateTransitionModels.cs
@@ -115,7 +115,7 @@ internal sealed record TransitionModel(
     TransitionArg From,
     TransitionArg Trigger,
     TransitionArg To,
-    Location Location,
+    LocationInfo Location,
     GuardResolution Guard,
     ActionResolution OnEnter,
     ActionResolution OnExit);
@@ -127,7 +127,7 @@ internal sealed record TransitionModel(
 internal sealed record StateParentModel(
     TransitionArg Child,
     TransitionArg Parent,
-    Location Location);
+    LocationInfo Location);
 
 /// <summary>
 /// The full state machine model extracted from a class marked with
@@ -141,7 +141,7 @@ internal sealed record StateMachineModel(
     EquatableArray<TransitionModel> Transitions,
     EquatableArray<StateParentModel> StateParents,
     bool IsHierarchical,
-    Location Location,
+    LocationInfo Location,
     bool IsValidHolder);
 
 /// <summary>
@@ -213,7 +213,7 @@ public ResolvedTransition(
         string fromMember,
         string triggerMember,
         string toMember,
-        Location location,
+        LocationInfo location,
         string fromExpression,
         string triggerExpression,
         string toExpression,
@@ -243,7 +243,7 @@ public ResolvedTransition(
 
     public string ToMember { get; }
 
-    public Location Location { get; }
+    public LocationInfo Location { get; }
 
     public string FromExpression { get; }
 
diff --git a/DesignPatterns.SourceGenerators/Generators/StateTransition/StateTransitionTransform.cs b/DesignPatterns.SourceGenerators/Generators/StateTransition/StateTransitionTransform.cs
index 9ff45aa..5fa0fa6 100644
--- a/DesignPatterns.SourceGenerators/Generators/StateTransition/StateTransitionTransform.cs
+++ b/DesignPatterns.SourceGenerators/Generators/StateTransition/StateTransitionTransform.cs
@@ -39,7 +39,7 @@ attribute.AttributeClass is not null &&
             return Result<StateMachineModel>.Empty;
         }
 
-        var location = context.TargetNode.GetLocation();
+        var location = new LocationInfo(context.TargetNode.GetLocation());
         var classDeclaration = (ClassDeclarationSyntax)context.TargetNode;
         var isValidHolder = classDeclaration.Modifiers.Any(SyntaxKind.StaticKeyword)
             && classDeclaration.Modifiers.Any(SyntaxKind.PartialKeyword);
@@ -105,7 +105,7 @@ attribute.AttributeClass is not null &&
             }
 
             var transitionLocation = attribute.ApplicationSyntaxReference is { } syntaxReference
-                ? syntaxReference.SyntaxTree!.GetLocation(syntaxReference.Span)
+                ? new LocationInfo(syntaxReference.SyntaxTree!.GetLocation(syntaxReference.Span))
                 : location;
 
             var from = ResolveTransitionArg(attribute.ConstructorArguments[0], stateType, stateTypeInfo);
@@ -167,7 +167,7 @@ attribute.AttributeClass is not null &&
                 }
 
                 var parentLocation = attribute.ApplicationSyntaxReference is { } syntaxRef
-                    ? syntaxRef.SyntaxTree!.GetLocation(syntaxRef.Span)
+                    ? new LocationInfo(syntaxRef.SyntaxTree!.GetLocation(syntaxRef.Span))
                     : location;
 
                 var child = ResolveTransitionArg(attribute.ConstructorArguments[0], stateType, stateTypeInfo);
diff --git a/DesignPatterns.SourceGenerators/Generators/StateTransition/StateTransitionValidator.cs b/DesignPatterns.SourceGenerators/Generators/StateTransition/StateTransitionValidator.cs
index e4fb43a..053df4e 100644
--- a/DesignPatterns.SourceGenerators/Generators/StateTransition/StateTransitionValidator.cs
+++ b/DesignPatterns.SourceGenerators/Generators/StateTransition/StateTransitionValidator.cs
@@ -30,7 +30,7 @@ internal static class StateTransitionValidator
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 DesignPatternsDiagnosticDescriptors.StateMachineHolderInvalid,
-                model.Location,
+                model.Location.ToLocation(),
                 model.Holder.Name));
             return null;
         }
@@ -47,7 +47,7 @@ internal static class StateTransitionValidator
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 DesignPatternsDiagnosticDescriptors.StateTransitionInvalidInitialState,
-                model.Location,
+                model.Location.ToLocation(),
                 model.Initial.DisplayValue,
                 stateType.FullyQualifiedName));
             return null;
@@ -116,7 +116,7 @@ private static List<ResolvedTransition> ResolveValidTransitions(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StateTransitionInvalidStateMember,
-                    transition.Location,
+                    transition.Location.ToLocation(),
                     transition.From.DisplayValue,
                     stateType.FullyQualifiedName));
                 continue;
@@ -126,7 +126,7 @@ private static List<ResolvedTransition> ResolveValidTransitions(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StateTransitionInvalidStateMember,
-                    transition.Location,
+                    transition.Location.ToLocation(),
                     transition.To.DisplayValue,
                     stateType.FullyQualifiedName));
                 continue;
@@ -136,7 +136,7 @@ private static List<ResolvedTransition> ResolveValidTransitions(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StateTransitionInvalidTriggerMember,
-                    transition.Location,
+                    transition.Location.ToLocation(),
                     transition.Trigger.DisplayValue,
                     triggerType.FullyQualifiedName));
                 continue;
@@ -204,7 +204,7 @@ private static void ReportDuplicateEdges(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StateTransitionDuplicateEdge,
-                    transition.Location,
+                    transition.Location.ToLocation(),
                     transition.FromMember,
                     transition.TriggerMember));
             }
@@ -216,7 +216,7 @@ private static void ReportIsolatedStates(
         EnumTypeInfo stateType,
         string initialMember,
         IReadOnlyCollection<ResolvedTransition> transitions,
-        Location location)
+        LocationInfo location)
     {
         var fromStates = new HashSet<string>(
             transitions.Select(static transition => transition.FromMember),
@@ -233,7 +233,7 @@ private static void ReportIsolatedStates(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StateTransitionIsolatedState,
-                    location,
+                    location.ToLocation(),
                     member.Name,
                     stateType.FullyQualifiedName));
             }
@@ -253,7 +253,7 @@ private static void ReportGuardDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 DesignPatternsDiagnosticDescriptors.StateTransitionGuardMethodNotFound,
-                transition.Location,
+                transition.Location.ToLocation(),
                 guard.Name,
                 holderName,
                 stateType.FullyQualifiedName,
@@ -265,7 +265,7 @@ private static void ReportGuardDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 DesignPatternsDiagnosticDescriptors.StateTransitionGuardMethodNotStatic,
-                transition.Location,
+                transition.Location.ToLocation(),
                 guard.Name,
                 holderName));
             return;
@@ -275,7 +275,7 @@ private static void ReportGuardDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 DesignPatternsDiagnosticDescriptors.StateTransitionGuardMethodWrongSignature,
-                transition.Location,
+                transition.Location.ToLocation(),
                 guard.Name,
                 holderName,
                 stateType.FullyQualifiedName,
@@ -285,7 +285,7 @@ private static void ReportGuardDiagnostics(
 
     private static void ReportActionDiagnostics(
         SourceProductionContext context,
-        Location location,
+        LocationInfo location,
         ActionResolution action,
         string holderName,
         EnumTypeInfo stateType,
@@ -295,7 +295,7 @@ private static void ReportActionDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 DesignPatternsDiagnosticDescriptors.StateTransitionActionMethodNotFound,
-                location,
+                location.ToLocation(),
                 action.Name,
                 holderName,
                 stateType.FullyQualifiedName,
@@ -307,7 +307,7 @@ private static void ReportActionDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 DesignPatternsDiagnosticDescriptors.StateTransitionActionMethodNotStatic,
-                location,
+                location.ToLocation(),
                 action.Name,
                 holderName));
             return;
@@ -317,7 +317,7 @@ private static void ReportActionDiagnostics(
         {
             context.ReportDiagnostic(Diagnostic.Create(
                 DesignPatternsDiagnosticDescriptors.StateTransitionActionMethodWrongSignature,
-                location,
+                location.ToLocation(),
                 action.Name,
                 holderName,
                 stateType.FullyQualifiedName,
@@ -352,7 +352,7 @@ private static void ReportActionDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StateParentInvalidMember,
-                    sp.Location,
+                    sp.Location.ToLocation(),
                     sp.Child.DisplayValue,
                     stateType.FullyQualifiedName));
                 hasFatalError = true;
@@ -363,7 +363,7 @@ private static void ReportActionDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StateParentInvalidMember,
-                    sp.Location,
+                    sp.Location.ToLocation(),
                     sp.Parent.DisplayValue,
                     stateType.FullyQualifiedName));
                 hasFatalError = true;
@@ -378,7 +378,7 @@ private static void ReportActionDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StateParentSelfReference,
-                    sp.Location,
+                    sp.Location.ToLocation(),
                     childName));
                 hasFatalError = true;
                 continue;
@@ -390,7 +390,7 @@ private static void ReportActionDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StateParentInvalidMember,
-                    sp.Location,
+                    sp.Location.ToLocation(),
                     $"{childName} already has parent '{existingParent}'",
                     stateType.FullyQualifiedName));
                 hasFatalError = true;
@@ -408,7 +408,7 @@ private static void ReportActionDiagnostics(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StateHierarchyCycle,
-                    model.Location,
+                    model.Location.ToLocation(),
                     cycle));
                 hasFatalError = true;
             }
@@ -470,7 +470,7 @@ private static void ReportOrphanParents(
         EnumTypeInfo stateType,
         Dictionary<string, string> parentMap,
         IReadOnlyCollection<ResolvedTransition> transitions,
-        Location location)
+        LocationInfo location)
     {
         var parentStates = new HashSet<string>(
             parentMap.Values,
@@ -486,7 +486,7 @@ private static void ReportOrphanParents(
             {
                 context.ReportDiagnostic(Diagnostic.Create(
                     DesignPatternsDiagnosticDescriptors.StateParentOrphanParent,
-                    location,
+                    location.ToLocation(),
                     parentState));
             }
         }
diff --git a/tests/DesignPatterns.SourceGenerators.Tests/Generators/ActionChainComposerTests.cs b/tests/DesignPatterns.SourceGenerators.Tests/Generators/ActionChainComposerTests.cs
index aea576b..4f8411a 100644
--- a/tests/DesignPatterns.SourceGenerators.Tests/Generators/ActionChainComposerTests.cs
+++ b/tests/DesignPatterns.SourceGenerators.Tests/Generators/ActionChainComposerTests.cs
@@ -210,12 +210,12 @@ public void BuildStateActionMap_CollectsExitActionsFromFromState()
     {
         var transitions = new List<ResolvedTransition>
         {
-            new("Draft", "Submit", "Submitted", location: null!,
+            new("Draft", "Submit", "Submitted", location: default,
                 "S.Draft", "T.Submit", "S.Submitted",
                 guardMethodReference: null,
                 onEnterSyncReference: null, onExitSyncReference: "Holder.OnExitDraft",
                 onEnterAsyncReference: null, onExitAsyncReference: null),
-            new("Submitted", "Pay", "Paid", location: null!,
+            new("Submitted", "Pay", "Paid", location: default,
                 "S.Submitted", "T.Pay", "S.Paid",
                 guardMethodReference: null,
                 onEnterSyncReference: null, onExitSyncReference: "Holder.OnExitSubmitted",
@@ -233,7 +233,7 @@ public void BuildStateActionMap_CollectsEnterActionsFromToState()
     {
         var transitions = new List<ResolvedTransition>
         {
-            new("Draft", "Submit", "Submitted", location: null!,
+            new("Draft", "Submit", "Submitted", location: default,
                 "S.Draft", "T.Submit", "S.Submitted",
                 guardMethodReference: null,
                 onEnterSyncReference: "Holder.OnEnterSubmitted", onExitSyncReference: null,
@@ -250,12 +250,12 @@ public void BuildStateActionMap_FirstWins_WhenMultipleExitActionsForSameState()
     {
         var transitions = new List<ResolvedTransition>
         {
-            new("Draft", "Submit", "Submitted", location: null!,
+            new("Draft", "Submit", "Submitted", location: default,
                 "S.Draft", "T.Submit", "S.Submitted",
                 guardMethodReference: null,
                 onEnterSyncReference: null, onExitSyncReference: "Holder.OnExitDraft1",
                 onEnterAsyncReference: null, onExitAsyncReference: null),
-            new("Draft", "Cancel", "Cancelled", location: null!,
+            new("Draft", "Cancel", "Cancelled", location: default,
                 "S.Draft", "T.Cancel", "S.Cancelled",
                 guardMethodReference: null,
                 onEnterSyncReference: null, onExitSyncReference: "Holder.OnExitDraft2",
@@ -281,18 +281,18 @@ public void Compose_CreatesCompositeDelegate_WhenChainHasMultipleActions()
 
         var transitions = new List<ResolvedTransition>
         {
-            new("Submitted", "Pay", "Paid", location: null!,
+            new("Submitted", "Pay", "Paid", location: default,
                 "S.Submitted", "T.Pay", "S.Paid",
                 guardMethodReference: null,
                 onEnterSyncReference: null, onExitSyncReference: "Holder.OnExitSubmitted",
                 onEnterAsyncReference: null, onExitAsyncReference: null),
-            new("Active", "Cancel", "Cancelled", location: null!,
+            new("Active", "Cancel", "Cancelled", location: default,
                 "S.Active", "T.Cancel", "S.Cancelled",
                 guardMethodReference: null,
                 onEnterSyncReference: null, onExitSyncReference: "Holder.OnExitActive",
                 onEnterAsyncReference: null, onExitAsyncReference: null),
             // Flattened inherited edge
-            new("Submitted", "Cancel", "Cancelled", location: null!,
+            new("Submitted", "Cancel", "Cancelled", location: default,
                 "S.Submitted", "T.Cancel", "S.Cancelled",
                 guardMethodReference: null,
                 onEnterSyncReference: null, onExitSyncReference: "Holder.OnExitActive",
@@ -327,7 +327,7 @@ public void Compose_NoOverride_WhenChainHasSingleAction()
 
         var transitions = new List<ResolvedTransition>
         {
-            new("Active", "Cancel", "Cancelled", location: null!,
+            new("Active", "Cancel", "Cancelled", location: default,
                 "S.Active", "T.Cancel", "S.Cancelled",
                 guardMethodReference: null,
                 onEnterSyncReference: null, onExitSyncReference: "Holder.OnExitActive",
@@ -352,7 +352,7 @@ public void Compose_NoOverride_WhenChainIsEmpty()
 
         var transitions = new List<ResolvedTransition>
         {
-            new("Draft", "Submit", "Submitted", location: null!,
+            new("Draft", "Submit", "Submitted", location: default,
                 "S.Draft", "T.Submit", "S.Submitted",
                 guardMethodReference: null,
                 onEnterSyncReference: null, onExitSyncReference: null,
diff --git a/tests/DesignPatterns.SourceGenerators.Tests/Generators/IncrementalCacheTests.cs b/tests/DesignPatterns.SourceGenerators.Tests/Generators/IncrementalCacheTests.cs
index 1a03b5e..9ce6d92 100644
--- a/tests/DesignPatterns.SourceGenerators.Tests/Generators/IncrementalCacheTests.cs
+++ b/tests/DesignPatterns.SourceGenerators.Tests/Generators/IncrementalCacheTests.cs
@@ -1,15 +1,89 @@
 using DesignPatterns.SourceGenerators.Generators;
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Text;
 
 namespace DesignPatterns.SourceGenerators.Tests.Generators;
 
 /// <summary>
 /// Verifies that incremental generator pipeline stages return Cached or Unchanged
-/// on the second run when the input compilation is identical. This validates the
-/// P0 refactoring (value-equatable models) and P2 (WithTrackingName instrumentation).
+/// on the second run when the input compilation is cloned. This validates the
+/// P0 refactoring (value-equatable models) and P1-#5 (LocationInfo value equality).
 /// </summary>
 public sealed class IncrementalCacheTests
 {
+    [Fact]
+    public void LocationInfo_Equals_AfterClone()
+    {
+        var parseOptions = new CSharpParseOptions(LanguageVersion.Latest);
+        var tree = CSharpSyntaxTree.ParseText("class A {}", parseOptions);
+        var compilation = CSharpCompilation.Create(
+            "Test",
+            new[] { tree },
+            new[] { MetadataReference.CreateFromFile(typeof(object).Assembly.Location) });
+
+        var cloned = compilation.Clone();
+        var clonedTree = cloned.SyntaxTrees.First();
+
+        var origNode = tree.GetRoot().DescendantNodes().First();
+        var clonedNode = clonedTree.GetRoot().DescendantNodes().First();
+
+        var info1 = new LocationInfo(origNode.GetLocation());
+        var info2 = new LocationInfo(clonedNode.GetLocation());
+
+        Assert.Equal(info1, info2);
+        Assert.Equal(info1.GetHashCode(), info2.GetHashCode());
+    }
+
+    /// <summary>
+    /// Verifies that <see cref="LocationInfo.ToLocation"/> reconstructs a
+    /// <see cref="Location"/> with the correct file path, source span, and
+    /// line span. The reconstructed location is an ExternalFileLocation (not
+    /// syntax-tree-backed), which is sufficient for Diagnostic.Create.
+    /// </summary>
+    [Fact]
+    public void LocationInfo_ToLocation_RoundTripsCoordinates()
+    {
+        var parseOptions = new CSharpParseOptions(LanguageVersion.Latest);
+        // Use a multi-line source so the line span is non-trivial.
+        var tree = CSharpSyntaxTree.ParseText(
+            """
+            class A
+            {
+                void M() { }
+            }
+            """,
+            parseOptions,
+            path: "Test.cs");
+
+        var methodNode = tree.GetRoot().DescendantNodes().First(n => n is MethodDeclarationSyntax);
+        var originalLocation = methodNode.GetLocation();
+        var info = new LocationInfo(originalLocation);
+
+        var reconstructed = info.ToLocation();
+
+        Assert.NotNull(reconstructed);
+        Assert.Equal("Test.cs", reconstructed!.SourceTree?.FilePath ?? reconstructed.GetLineSpan().Path);
+        Assert.Equal(originalLocation.SourceSpan, reconstructed.SourceSpan);
+
+        var expectedLineSpan = originalLocation.GetLineSpan().Span;
+        var actualLineSpan = reconstructed.GetLineSpan().Span;
+        Assert.Equal(expectedLineSpan, actualLineSpan);
+    }
+
+    /// <summary>
+    /// Verifies that a null Location produces a default LocationInfo whose
+    /// ToLocation returns null (no crash).
+    /// </summary>
+    [Fact]
+    public void LocationInfo_NullLocation_ToLocationReturnsNull()
+    {
+        var info = new LocationInfo(null);
+        Assert.Null(info.ToLocation());
+        Assert.Null(info.FilePath);
+    }
+
     [Fact]
     public void GenerateSingletonCachesOnSecondRun()
     {
diff --git a/tests/DesignPatterns.SourceGenerators.Tests/SourceGeneratorTestContext.cs b/tests/DesignPatterns.SourceGenerators.Tests/SourceGeneratorTestContext.cs
index c6a433a..28a8296 100644
--- a/tests/DesignPatterns.SourceGenerators.Tests/SourceGeneratorTestContext.cs
+++ b/tests/DesignPatterns.SourceGenerators.Tests/SourceGeneratorTestContext.cs
@@ -250,14 +250,15 @@ internal static void AssertCacheHit<TGenerator>(params (string Path, string Sour
         // First run — populates the cache.
         driver = driver.RunGeneratorsAndUpdateCompilation(compilation, out _, out _);
 
-        // Second run — same compilation; our tagged stages should be cached.
-        // We use the same compilation (not Clone) because Location uses reference
-        // equality: Clone forces the transform to re-execute, producing new
-        // Location objects that break model value equality even though the
-        // semantic content is identical. Using the same compilation verifies
-        // that the transform outputs are cached when inputs are unchanged,
-        // which is the guarantee the P0 refactoring restored.
-        var secondResult = driver.RunGenerators(compilation).GetRunResult();
+        // Second run — cloned compilation; our tagged stages should be cached.
+        // We use Clone (not the same compilation) to verify that LocationInfo
+        // value equality holds across cloned compilations. Previously, Location
+        // used reference equality, so Clone forced the transform to re-execute
+        // and broke model value equality. With LocationInfo (value-equatable),
+        // the transform outputs are cached even when Clone creates new syntax
+        // trees and Location objects.
+        var clonedCompilation = compilation.Clone();
+        var secondResult = driver.RunGenerators(clonedCompilation).GetRunResult();
 
         // Collect all tracking names defined in TrackingNames so we only check
         // our own stages, not Roslyn-internal ones (Compilation, etc.).