Consider using the GitHub Checks API about participate.whatwg.org HOT 2 OPEN

I might be missing something, but is this not a problem?

Note: The Checks API only looks for pushes in the repository where the check suite or check run were created. Pushes to a branch in a forked repository are not detected and return an empty pull_requests array.

Or does it no longer solely count as a branch on a forked repository once a pull request is made?

from participate.whatwg.org.

Interesting. I think "it no longer solely count as a branch on a forked repository once a pull request is made" is the case in a technical sense, but that's always felt like an undocumented side effect of the GitHub infrastructure, and not something to rely on. I wonder what happens in practice.

It does seem like the API would be pretty useless if it didn't detect updates to PRs made from forks, so I suspect it works. But that wording is strange.

from participate.whatwg.org.