Vanity URLs

// app_url = https://console.mycompany.com
// api_url = https://console.mycompany.com/gateway
const FRONTEND_ORIGIN = "your-app.apps.yourcompany.com";      // static frontend
const API_ORIGIN      = "your-app.api.apps.yourcompany.com";  // API + OAuth
const API_PREFIX      = "/gateway";                                 // the path in api_url

export default {
  async fetch(request) {
    const url = new URL(request.url);
    const underApi =
      url.pathname === API_PREFIX || url.pathname.startsWith(API_PREFIX + "/");

    // Pick the origin, and strip the /gateway prefix for API traffic so the app sees
    // its own paths (/api, /oauth, /auth, /.well-known, /mcp).
    const origin = new URL(url);
    origin.hostname = underApi ? API_ORIGIN : FRONTEND_ORIGIN;
    origin.pathname = underApi ? url.pathname.slice(API_PREFIX.length) || "/" : url.pathname;

    // Dropping the incoming Host lets the request go out with Host: <internal>,
    // so Synthetiq's edge routes it to the right app. redirect: "manual" lets
    // OAuth redirects flow back to the browser instead of being followed here.
    const headers = new Headers(request.headers);
    headers.delete("Host");
    return fetch(origin.toString(), {
      method: request.method,
      headers,
      body: request.body,
      redirect: "manual",
    });
  },
};