Replaces the three hardcoded dispatches in actionCable.onCacheInvalidate and
ReconnectService.revalidateCaches with a loop over cacheableModels. Adding a
new cached model no longer requires editing these two handlers — they pick
it up automatically from the registry.
Also guards against partial server payloads: dispatches are skipped for
models whose key is undefined, so a client running ahead of a server
deploy keeps working without spurious dispatches.
Shivam Mishra
1a61e8102e