Bring the CI you already have

A check is reported against a commit

Not against a pull request. The same report then serves every pull request whose head is that commit, and it stays meaningful when a branch moves.

The awkward cases decide whether this is useful

Any implementation handles green and red. What separates a useful checks system from an annoying one is everything in between.

• A retried check is judged on its latest run, so one failed attempt does not keep a commit red forever
• Neutral and skipped count as passing, because a path-filtered job that had nothing to say has not found a problem
• Cancelled and stale are neither pass nor fail, because something will report again
• A check nobody marked required never blocks a merge, however red it is

Never reported is not the same as still running

A required check that has never reported means the workflow is not wired up and never will report. A pending one resolves itself. The person waiting is told which of the two they are looking at, because the actions are completely different.

Stale runs do not carry over

When a branch is force pushed, checks that ran against the old head describe code nobody is merging. Leaving them green is how an unverified commit slips past a required check.