[zaphirplane]

> assuming you know what the URL

This is the tricky bit thou and will come down to chicken and egg problem of adopting some convention

[01HNNWZ0MV43FF]

Actually it's super-easy, barely an inconvenience.

Dedicate a portion of your site to notifications. Allocate the URL there with a blank page that has a meta 404 tag or something.

When blog post is live, replace the meta 404 with a meta redirect to the real permalink.

You can do an all-manual URL shortener for QR codes the same way. That means you can also have a QR code for this kind of subscription, which is cool

[zaphirplane]

How does the user agent know this is 2 of 4 or 2 of 2

Anyways the convention isn’t too hard it’s the adoption by authors and software that will be tricky

[losvedir]

Ah yeah, simple manual methods are tight.

[dragonwriter]

> This is the tricky bit thou and will come down to chicken and egg problem of adopting some convention

Sure, there needs to be a standard for this, but it could be as simple as using a new rel value, say, “futurecontent”, and title (when used with <link>) or content (when used with <a>) giving the description of what will be found at the link when it is ready.