Serialized users and groups now have two new fields: youCan and theyDid. These fields are arrays of strings and represents actions, that the current user can perform over the object (youCan) and actions, that the object performed over the current user (theyDid). The incomplete list of actions is: "post", "dm", "(un)subscribe", "(un)ban", "block", "(un)request_subscription" and so on.
Added
RFC and discussion: https://freefeed.net/ffdev/314b821d-1314-4989-9330-f3c811866cb8