Gregory's Server
@evan whatever the mechanism i do think isActivity() needs to be specified within mainline AP. i know we have a primer page but having it in-spec would be really useful too.
something similar for allowing Actor to be declared on objects with ldp:inbox and as:outbox could also be useful if we *really* wanna avoid duck-typing. although i am not as opposed to duck-typing as you are…
the definition of as:Actor would specifically be “my ldp:inbox dereferences to a Collection of Activity or subtype”
@evan in other words if something is an Actor then it is expected that you can send Activity notifications to it as opposed to generic LDN, and crucially, ***it will handle those activities with side-effects defined in activitypub***
it therefore may also make sense to define Actor and isActor() at the spec level