1. A memory system for a node, the memory system comprising: a cache including: a cache directory; a data array; and a cache controller configured to: interrogate the cache directory to determine whether a shared cache line to be installed in the data array is associated with an invalid global state, 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, spawn a castout invalid global command for the shared cache line; install the received shared cache line in the data array; and update a coherence state for the shared cache line in the cache directory to indicate the shared cache line is shared.