A model has an owner (org, team or project). Quotas guarantee a scope GPUs, cores and memory and may limit it; what a scope holds is summed from its models' replicas and those beneath it. A replica within its owner's guarantee is not taken for another scope; what is held beyond a guarantee is borrowed and taken back for a scope within its own. A limit stops a model before it starts, and headroom stops there too. ctl quota and ctl model owner set them; metrics and a CapacityAtLimit alert report them. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>