This stuff is all rather boring or frustrating when you just want to get your app finished

Handling 401s well is important for the user's experience. They won't happen often (though more often than I expected), but really do break everything if you're not careful. Getting a good authentication abstraction library for Vue or Ember or whatever you are using should help with a lot of the boring parts. You'll probably need to define some extra strategies/rules for this cookie session approach, but if it's anything like in ember-simple-auth they're so simple it feels like cheating, because the Rails app is doing all of the hard work and you just need the js part to spot a 401 and handle logging in and retrying whatever it was doing before.

Building an app with all the modern best practices — code-splitting, offline support, server-rendered views with client-side hydration — is fiendishly complicated. SvelteKit does all the boring stuff for you so that you can get on with the creative part.

we have a helpful little framework behind the page rendering that pulls code snippets from real tests out of the actual gems

Writing documentation for the new website has been fun. Yes, fun!

Keeping bootstrap-sass in sync with upstream changes from Bootstrap used to be an error prone and time consuming manual process. With Bootstrap 3 we have introduced a converter that automates this.

Because of those similarities, it's possible to automate some of the changes.

Use tools in preference to unskilled help to lighten a programming task, even if you have to detour to build the tools and expect to throw some of them out after you've finished using them.

that can be partially automated but still require human oversight and occasional intervention

Part of why most code -- and most software -- sucks so much is that making sweeping changes is hard.

As technology improves, humans keep integrating these extra abilities into our cyborg selves