How to grant writable permission to lithium via REST API?

fengka

You api call might be like this rest("/messages/id/[messageid]/kudos/give");

Change this to restadmin("/messages/id/[messageid]/kudos/give");

restadmin = it's an object to make a REST call with Administrator permissions on behalf of the user . This call essentially bypasses permission checks for the current user

I hope this helps you :)