With cancel-in-progress: false, pending CI runs accumulate in the
ci-staging concurrency group. New pushes create queued runs, but
GitHub dispatches multiple runs for the same SHA instead of replacing
the pending one. All runs get stuck/cancelled before completing.
Reverting to cancel-in-progress: true restores CI operation — runs
that are superseded are cancelled, freeing the concurrency slot for
the new run to proceed.
Runner availability (ubuntu-latest dispatch stall) is a separate
infra issue tracked independently.
23be5083e4