I guess there’s sort of a tradition for WordPress developers where they start out by forking code they don’t really understand and then release it upon the world while not fully grokking how it works or how to maintain it.
There’s probably not much of a better way to learn how this stuff works in the first place. (If you know of one, certainly let me know.)
When transitioning this site to use HTTPS recently on the front-end, there was a problem with existing legacy content not conforming to the new URI scheme. In an effort to solve this problem, I did what any self-respecting novice coder would do: I asked everyone I knew who is smarter than me for help.
I was led by my colleagues on the WordPress.com VIP to a code snippet that was written at Code for the People to handle exactly such a problem. It filters content to ensure that the URI scheme matches the scheme that’s set in a given site’s options. It’s been running on this site for some time now and I’m happy to say that it appears to work quite beautifully.
Assuming that others would be able to use this as well, I’m releasing the plugin on GitHub and with a reference page here, encouraging issues and pull requests as you might feel moved to create them. I can’t promise that I’ll know what to do with those requests, but I’ll do what I can to keep it properly maintained.
I hope you do indeed find it useful.