@dualmark/fastly

Fastly Compute edge adapter for the Dualmark Answer Engine Optimization (AEO) framework.

Installation

npm install @dualmark/fastly @dualmark/core

Usage

Create your Fastly Compute handler using createAEOFetchEventHandler.

import { createAEOFetchEventHandler } from "@dualmark/fastly";

const handler = createAEOFetchEventHandler({
  backend: "my_html_backend",
  markdownBackend: "my_markdown_backend", // Optional, defaults to backend
});

addEventListener("fetch", (event) => {
  event.respondWith(handler(event));
});

Fastly Backend Setup

Unlike other serverless environments where you provide an upstream handler function, Fastly routes requests to explicit Backends.

You must define your backends in your fastly.toml or via the Fastly dashboard:

[setup.backends.my_html_backend]
  address = "example.com"
  port = 443

Pass the name of this backend to the adapter via the backend option.

markdownBackend Explanation

By default, the adapter will look for .md files on the same backend defined in backend. However, you can separate your markdown serving (e.g., from an AWS S3 bucket) from your HTML serving (e.g., a dynamic application).

Provide markdownBackend: "your_s3_backend" to tell the adapter to fetch .md requests from a different origin.

Production Deployment

When deploying to Fastly Compute, ensure you've configured the correct backend addresses for production environments.

Use the Fastly CLI to deploy your service:

fastly compute publish

[!WARNING] Warning about backend loops: If you accidentally misconfigure your backend to point back to your Fastly service itself (rather than the origin serving the content), it can create an infinite fetch loop. Ensure the backend name corresponds to the external origin serving your HTML or Markdown.

AEO Spec Checklist

This adapter handles the following Dualmark AEO specifications:

• [x] AI bot UA detection
• [x] Accept: text/markdown negotiation
• [x] 406 Not Acceptable handling
• [x] .md asset passthrough
• [x] Internal & external redirects
• [x] Link: rel="alternate" header injection on HTML responses
• [x] Vary: Accept header injection
• [x] Trailing slash normalization