feat: add SPA route rewrite CloudFront Function to StaticSiteConstruct

[ncipollina]

Summary

Adds a CloudFront Function (viewer request event) to the default S3 behavior in StaticSiteConstruct that rewrites requests with no file extension to /index.html. This enables correct client-side routing for Blazor WASM and other SPAs — specifically fixing cases where routes like /profile or /authentication/login-callback returned 404 instead of loading the app.

The previous workaround (distribution-level 404 → /index.html error response) couldn't be used because it would also swallow legitimate API 404 responses. The CloudFront Function approach is safe because API requests match the /api/* behavior (a separate Lambda origin) and never reach the default behavior where this function runs.

Changes

• StaticSiteConstruct.cs — creates a CloudFront.Function with a JS_2_0 viewer request handler and attaches it to DefaultBehavior.FunctionAssociations

Rewrite logic:

function handler(event) {
    var uri = event.request.uri;
    if (!uri.match(/\.[a-zA-Z0-9]+$/)) {
        event.request.uri = '/index.html';
    }
    return event.request;
}

Validation

• dotnet build passes with 0 warnings across net8.0 / net9.0 / net10.0 targets
• Extension matching covers all Blazor WASM asset types: .js, .wasm, .css, .json, .br, .gz, .ico, .png, .svg
• SPA routes (/profile, /authentication/login-callback, /) correctly rewrite to /index.html
• API paths (/api/*) use a separate CloudFront behavior and are never affected

Notes for Reviewers

The existing 403 → /index.html distribution-level error response is retained as a safety net for any S3 access-denied scenarios. The CloudFront Function handles the primary SPA routing case at the request level before S3 is ever reached.

This change applies to all consumers of StaticSiteConstruct — any static site using this construct is a SPA and benefits from this behavior unconditionally.

[chatgpt-codex-connector]

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.
To continue using code reviews, you can upgrade your account or add credits to your account and enable them for code reviews in your settings.

[Copilot]

Pull request overview

Adds CloudFront viewer-request rewriting to support SPA client-side routing in StaticSiteConstruct, plus an optional Cognito User Pool post-confirmation trigger hook, and bumps package/library versions.

Changes:

• Add a CloudFront Function to rewrite extensionless paths to /index.html on the default behavior (SPA routing fix).
• Add optional PostConfirmationTrigger support to CognitoUserPoolConstruct.
• Bump Amazon.CDK.Lib and the library VersionPrefix.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/LayeredCraft.Cdk.Constructs/StaticSiteConstruct.cs	Introduces a CloudFront Function and associates it with the default behavior to enable SPA route rewrites.
src/LayeredCraft.Cdk.Constructs/Models/CognitoUserPoolConstructProps.cs	Extends Cognito props with an optional post-confirmation Lambda trigger property.
src/LayeredCraft.Cdk.Constructs/CognitoUserPoolConstruct.cs	Wires the optional post-confirmation trigger into the created Cognito User Pool.
Directory.Packages.props	Updates Amazon.CDK.Lib dependency version.
Directory.Build.props	Bumps package version prefix.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.