While I understand the appeal of the idea , however i think It's a good idea to keep the cache directory project specific because this maintains a proper separation of concerns but also helps make debugging project specific issues,whose symptoms might surface in a compiled module in the cache directory like in this specific case: unslothai/unsloth#2179, much faster and much cleaner.

Interesting. But if patches don't conflict with other patches, maintaining a global cache is equivalent to maintaining a local cache (even from a debugging perspective)
So I sort of find local cache unnecessary... It creates lot of duplicate folders and hard to keep track of where is what...