sw.js

const staticCacheName = 'static-e6350322ee01';
const expectedCaches = [
  staticCacheName
];

self.addEventListener('install', event => {
  self.skipWaiting();

  event.waitUntil(
    caches.open(staticCacheName)
      .then(cache => cache.addAll([
        "/shell-start.cbd594dfa81d.inc",
        "/shell-end.cbd594dfa81d.inc",
        "/offline.d989ddb2d13b.inc",
        "/error.ba6821d4f751.inc",
        "https://themes.googleusercontent.com/static/fonts/inconsolata/v6/BjAYBlHtW3CJxDcjzrnZCCwlidHJgAgmTjOEEzwu1L8.ttf",
        "https://themes.googleusercontent.com/static/fonts/ptserif/v5/EgBlzoNBIHxNPCMwXaAhYHYhjbSpvc47ee6xR_80Hnw.ttf",
        "/static/js/main.6e994df71e3d.js",
        "/static/css/all.9281a377cb2c.css"
      ]))
  );
});

// remove caches that aren't in expectedCaches
self.addEventListener('activate', event => {
  event.waitUntil(
    caches.keys().then(keys => Promise.all(
      keys.map(key => {
        if (!expectedCaches.includes(key)) return caches.delete(key);
      })
    ))
  );
});

function createPageStream(request) {
  const stream = new ReadableStream({
    start(controller) {
      // the body url is the request url plus 'include'
      const url = new URL(request.url);
      url.pathname += 'include';

      const startFetch = caches.match('/shell-start.cbd594dfa81d.inc');
      const endFetch = caches.match('/shell-end.cbd594dfa81d.inc');
      const middleFetch = fetch(url).then(response => {
        if (!response.ok && response.status != 404) {
          return caches.match('/error.ba6821d4f751.inc');
        }
        return response;
      }).catch(err => caches.match('/offline.d989ddb2d13b.inc'));

      function pushStream(stream) {
        const reader = stream.getReader();

        return reader.read().then(function process(result) {
          if (result.done) return;
          controller.enqueue(result.value);
          return reader.read().then(process);
        });
      }

      startFetch
        .then(response => pushStream(response.body))
        .then(() => middleFetch)
        .then(response => pushStream(response.body))
        .then(() => endFetch)
        .then(response => pushStream(response.body))
        .then(() => controller.close());
    }
  });

  return new Response(stream, {
    headers: {'Content-Type': 'text/html; charset=utf-8'}
  });
}

self.addEventListener('fetch', event => {
  const url = new URL(event.request.url);

  if (url.origin === location.origin) {
    // home or article pages
    if (url.pathname === '/' || /^\/20\d\d\/[a-z0-9-]+\/$/.test(url.pathname)) {
      event.respondWith(createPageStream(event.request));
      return;
    }
  }

  // cache-first for the rest
  event.respondWith(
    caches.match(event.request).then(r => r || fetch(event.request))
  );
});

This looks something great, I am going to try it out!