Engineering cost ownership, by team, by day.

The platform team had become accidentally responsible for cost optimisation. They’d optimise; teams would un-optimise; the cycle repeated. The teams didn’t have the data — they didn’t know what their workloads cost.

The CUR landed in S3 as Parquet, partitioned by date and team-tag. Athena queries assembled per-team rollups; QuickSight rendered team-specific dashboards embedded in Backstage. Each team’s dashboard surfaced its own top spenders, anomalies, and trend.

Per-team cost visibility went from "quarterly, on request" to "daily, on the wall." A cost-aware PR review culture emerged organically — engineers started flagging "this might be expensive" in reviews without being prompted. Inefficient workloads dropped 38% as teams self-optimised the obvious wins.