Buildkite change history: Jobs not starting on hosted agents and agent-stack-k8s

Buildkite reported a major Agent API outage: jobs failed to start on hosted agents, agent-stack-k8s and other implementations using acquire job. The incident started at 2026-05-07 08:48 UTC and was resolved at 2026-05-07 09:37 UTC, lasting 49 minutes. Buildkite reverted a change that supplied stale environment variables to acquire job.