Tier Ceiling. The maximum risk tier an actor, role, connector, module, or delegated authority is allowed to attempt in a given execution mode and scope.
A tier ceiling turns authority into a bounded fact. It is not the action's risk; that is the risk tier. It is the upper limit the platform will allow for this actor right now. If the requested action exceeds the ceiling, the system must refuse, escalate, require a different approval mode, or route to a human-only decision before execution.