I need a local, persistent key/value store that works well with Go. 

Transaction support is not needed, I will just do simple atomic reads/writes to implement a local cache of data fetched from a farcaster hub (ex: fid->fname, castId->cast_data, etc)

It would be nice (not required) if it provided some pruning mechanism out of the box that lets me prune entries after a specific number of entries is reached.

I'm open to test something that fits the requirements but it's not 100% battle-tested, my app is not mission critical and can easily recover if things break once in a while.

Dad, geek, conversation liquidity provider. vrypan.net (home), /weatherxm (work), @l--o--l (fun). Also https://paragraph.xyz/@purplesubmarine

For your use case, BoltDB or Badger would be great options