Class PostureApi

Find the (host, slot) pair the candidate currently occupies that is posture-bearing (i.e. its SlotSpec.postures is non-empty). Returns null if the candidate occupies no posture-bearing slot.

The substrate guarantees a single actor occupies at most one posture-bearing slot at a time — transferPosture enforces this by vacating before occupying. The first match wins.

Atomic posture transfer. Vacates any current posture-bearing slot, finds a slot on target accepting posture, occupies it, and sets the actor's Posed posture string.

verb is used only for the "no posture-accepting slot" failure surface ("you can't sit on …") — every other failure phrases itself naturally without the verb name.

Throws on type-shape violations (target not Postured, actor not Posed/Slottable) — those are validator-should-have-caught cases, not user-facing failures.

Vacate every posture-bearing slot the actor currently occupies. Returns the count of slots vacated. No-op if the actor isn't Slottable. Does NOT touch the actor's Posed posture string — callers (typically StandController) flip it to Postures.Stand separately so the value is explicit at the call site.