What if smart wallets had keys with different auth levels? 

1. A root key, which can do anything, which lives in your fav wallet
2. An FC key, which can only interact with FC contracts, which lives in Warpcast 

Is there a standard for something like this?

i think a Safe might do. could implement a Safe Guard where the Guard checks for a whitelist if the tx is being signed the FC key.

Technowatermelon. Elder Millenial. Building Farcaster. 

nf.td/varun

i think a Safe might do. could implement a Safe Guard where the Guard checks for a whitelist if the tx is being signed the FC key. 
https://docs.safe.global/advanced/smart-account-guards