1. A method of operating a memory system for a node, comprising: interrogating, by a cache, an associated cache directory to determine whether a shared cache line to be installed in the cache is associated with an invalid global state in the cache, wherein the invalid global state specifies that a version of the shared cache line has been intervened off-node; in response to the shared cache line being in the invalid global state, spawning, by the cache, a castout invalid global command for the shared cache line; installing, by the cache, the shared cache line in the cache; and updating, by the cache, a coherence state for the shared cache line in the associated cache directory to indicate the shared cache line is shared.