The autoPrune flags passed '--volumes' WITH '--filter until=24h', which docker
rejects ('until filter not supported with --volumes') — so docker-prune.service
FAILED every day (system 'degraded') and never reclaimed anything (a cause of the
disk creeping to 96%). Worse, '--volumes' prunes volumes with no running
container — which would DELETE Phase-2w DATA-WARM canonical volumes (undeployed by
design). Removed '--volumes': now prunes images/containers/networks/build-cache
older than 24h only; warm volumes survive and are pruned deliberately by the warm
reconcilers (WC8).
Verified: nixos-rebuild switch -> docker-prune.service runs clean, system
'running' (0 failed units), warm keycloak still 200.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>