Maybe I'm misunderstanding something, but you can add filters to RSS feeds. What is proposed is pretty much just RSS, except for one specific item. Yes, it's more work on your side, but asking the creator to manage updates for whatever one thing any/every random person is interested in is pretty unrealistic, especially since the people asking for this are going to be explicitly not interested in everything else about the creator.

> There’s no AI to this. No magic. No problems to be solved.

Why would you not involve yourself in the new hotness? You _can_ put AI into this. Instead of using some expression to figure out whether a new article has links to the previous ones in the series / a matching title, you can have a local agent check your RSS feed and tell you if it's what you're looking for, or else delete the article. For certain creators this might even be a sensible choice, depending on how purple their prose is and their preferred website setup.

> Yes, it's more work on your side

How much work, and is Part 3 gonna be so mindblowing to be worth it?

> asking the creator to manage updates for whatever

Managing updates in this case is...posting Part 3? Something they were already gonna do? Except now there's also some machine-only endpoint that needs to start returning "Yes" instead of "No"? Doesn't sound like a ton of work.

> Why would you not involve yourself in the new hotness? You _can_ put AI into this.

Because just involving yourself with the new hotness just because it is the new hotness is pathetic. I can put AI into this, but why would I? Why would I add all the heft and complexity and stupid natural language bullshit talking to a computer when I could just press a button that will do this for me deterministically?