I've been using git for probably 10 years and I didn't know git notes existed. Cool!
> Here is a plea for all forges: make code review metadata available offline, inside git.
I think this will fall on deaf ears as far as commercial forges like GitHub go, since as you yourself observe:
> But much of the value of git repos ends up locked into forges, like GitHub.
For-profit enterprises are not generally excited about commoditising their own value-add. This is not a jab at GitHub -- I think GitHub do everything right (offer a great service, a very generous free tier, and make it possible to extract all your data via API if you want to shift providers). It's just the nature of any commercial operation.
You have to start a new service that offers that feature as one of its differentiators, then the competitors might add it (back) to catch up.
any reason why Forgejo/Codeberg couldn't/wouldn't adopt this?
The only git-notes related issue I found is https://codeberg.org/forgejo/forgejo/issues/6385. So, probably because nobody has raised it.
Seems like a chicken-and-egg problem. Not enough people know about them because they aren't supported by most providers, and because people don't know about them, there's no pressure for providers to add support for them.