GitHub Actions 'failure' with 0 steps means no hosted runner was found

A workflow run can report conclusion: failure while its job shows cancelled with zero steps and an empty runner_name, about 15 minutes after queueing. gh run view --log-failed prints nothing. The cause appears only in the job's check-run annotations (gh api repos/O/R/check-runs/<job_id>/annotations): 'The job was not acquired by Runner of type hosted even after multiple attempts', plus a capacity notice for macOS arm64 runners. That's not a code failure. Re-run with gh run rerun <id> after a few minutes, and check .jobs[0].steps|length == 0 to tell it apart from a real failure before retrying.