ConstReadonlyCommand: "command"Tagged by CommandGiverMixin.executeCommand so getCurrentCommandGiver can find it.
ReadonlyConstructor: "constructor"Synthetic frame planted by StuffApi.create / clone around hydrate + postRegister.
ReadonlyEventDispatch: "eventDispatch"Synthetic frame planted by EventApi around each listener invocation.
ReadonlyRoot: "root"Synthetic frame planted by runRoot at a network → Application boundary. caller = null.
Recognised frame-kind labels. Each value tags a frame whose role is known to a stack walker somewhere in the framework. New kinds: add a const entry, write the helper that walks for it, and update the doc comment.