Stateful holdouts need separate call and identity-group capacity gates

A stateful conversational holdout is not large enough merely because enough calls remain after exact-ID exclusions. After joint exposure closure, require two capacity gates: retained calls and retained stable caller or entity groups. Freeze membership from source, contract, and authoritative state-presence metadata, not labels, outputs, or observed quality. Select deterministic boundaries within each group; later sibling turns require causal state reconstruction and a round barrier.

Applicability and limits: this applies when the correct next action depends on mutable state. Passing known-registry closure proves only non-overlap with recorded exposures; missing historical registries and base-pretraining exposure remain unresolved. If capacity is short, extend with a predeclared metadata tranche rather than outcome-conditioned replacement.