feat: add SPA route rewrite CloudFront Function to StaticSiteConstruct

Directory.Build.props

@@ -1,6 +1,6 @@
 <Project>
     <PropertyGroup>
-        <VersionPrefix>2.3.0</VersionPrefix>
+        <VersionPrefix>2.4.0</VersionPrefix>
         <!-- SPDX license identifier for MIT -->
         <PackageLicenseExpression>MIT</PackageLicenseExpression>
 

Directory.Packages.props

@@ -7,7 +7,7 @@
     <PackageVersion Include="Microsoft.Testing.Extensions.CodeCoverage" Version="18.5.2" />
   </ItemGroup>
   <ItemGroup Label="AWS">
-    <PackageVersion Include="Amazon.CDK.Lib" Version="2.246.0" />
+    <PackageVersion Include="Amazon.CDK.Lib" Version="2.248.0" />
   </ItemGroup>
   <ItemGroup Label="Testing">
     <PackageVersion Include="AutoFixture" Version="4.18.1" />

src/LayeredCraft.Cdk.Constructs/CognitoUserPoolConstruct.cs

@@ -2,6 +2,8 @@
 using Amazon.CDK;
 using Amazon.CDK.AWS.CertificateManager;
 using Amazon.CDK.AWS.Cognito;
+using Amazon.CDK.AWS.IAM;
+using Amazon.CDK.AWS.Lambda;
 using Amazon.CDK.AWS.Route53;
 using Amazon.CDK.AWS.Route53.Targets;
 using Constructs;
@@ -63,6 +65,16 @@ public CognitoUserPoolConstruct(
             RemovalPolicy = props.RemovalPolicy,
         });
 
+        if (props.PostConfirmationTrigger is not null)
+        {
+            UserPool.AddTrigger(UserPoolOperation.POST_CONFIRMATION, props.PostConfirmationTrigger);
+            props.PostConfirmationTrigger.AddToRolePolicy(new PolicyStatement(new PolicyStatementProps
+            {
+                Actions = ["cognito-idp:AdminAddUserToGroup"],
+                Resources = ["*"],
+            }));
+        }
+
         var resourceServers = CreateResourceServers(props);
 
         ResourceServers = resourceServers;

src/LayeredCraft.Cdk.Constructs/Models/CognitoUserPoolConstructProps.cs

@@ -1,5 +1,6 @@
 using Amazon.CDK;
 using Amazon.CDK.AWS.Cognito;
+using Amazon.CDK.AWS.Lambda;
 
 namespace LayeredCraft.Cdk.Constructs.Models;
 
@@ -21,6 +22,7 @@ public interface ICognitoUserPoolConstructProps
     IReadOnlyList<ICognitoUserPoolAppClientProps> AppClients { get; }
     ICognitoUserPoolDomainProps? Domain { get; }
     IReadOnlyCollection<ICognitoUserPoolGroupProps>? Groups { get; }
+    IFunction? PostConfirmationTrigger { get; }
 }
 
 public sealed record CognitoUserPoolConstructProps : ICognitoUserPoolConstructProps
@@ -40,4 +42,5 @@ public sealed record CognitoUserPoolConstructProps : ICognitoUserPoolConstructPr
     public IReadOnlyList<ICognitoUserPoolAppClientProps> AppClients { get; init; } = [];
     public ICognitoUserPoolDomainProps? Domain { get; init; }
     public IReadOnlyCollection<ICognitoUserPoolGroupProps>? Groups { get; init; } = [];
+    public IFunction? PostConfirmationTrigger { get; init; } = null;
 }

src/LayeredCraft.Cdk.Constructs/StaticSiteConstruct.cs

@@ -72,6 +72,27 @@ public StaticSiteConstruct(Construct scope, string id, IStaticSiteConstructProps
             SubjectAlternativeNames = props.AlternateDomains,
         });
 
+        // CloudFront Function: rewrite SPA routes (no file extension) to /index.html
+        // so client-side routes are handled by the app rather than returning 404.
+        // Requests with a file extension pass through unchanged, preserving normal
+        // asset serving and ensuring API 404s (served via the /api/* behavior) are
+        // never affected — they never reach this default behavior.
+        var spaRewriteFunction = new Amazon.CDK.AWS.CloudFront.Function(this, $"{id}-spa-rewrite",
+            new Amazon.CDK.AWS.CloudFront.FunctionProps
+            {
+                Code = FunctionCode.FromInline("""
+                    function handler(event) {
+                        var uri = event.request.uri;
+                        if (!uri.match(/\.[a-zA-Z0-9]+$/)) {
+                            event.request.uri = '/index.html';
+                        }
+                        return event.request;
+                    }
+                    """),
+                Runtime = FunctionRuntime.JS_2_0,
+                Comment = "Rewrite SPA routes to /index.html for client-side routing"
+            });
+
         // Create CloudFront distribution for global content delivery
         var distribution = new Distribution(this, $"{id}-cdn", new DistributionProps
         {
@@ -83,7 +104,15 @@ public StaticSiteConstruct(Construct scope, string id, IStaticSiteConstructProps
                     ProtocolPolicy = OriginProtocolPolicy.HTTP_ONLY
                 }),
                 AllowedMethods = AllowedMethods.ALLOW_GET_HEAD,
-                Compress = true
+                Compress = true,
+                FunctionAssociations =
+                [
+                    new FunctionAssociation
+                    {
+                        Function = spaRewriteFunction,
+                        EventType = FunctionEventType.VIEWER_REQUEST
+                    }
+                ]
             },
             Certificate = certificate,
             ErrorResponses =