There is no way to discover the actor ID from author's profile (/author/<username>). Many Fediverse platforms redirect to an actor document if Accept header specifies the ActivityPub media type, but not Ghost.
One can try to guess the actor ID using the https://<domain>/.ghost/activitypub/users/<username> template, but this is not reliable. It seems to work only when the username is index, in other cases an invalid actor document is returned. The username is not checked, by the way, and document is returned even if the user doesn't exist. Here's an example: https://activitypub.ghost.org/.ghost/activitypub/users/wowsuchactor
There is no way to discover the actor ID from author's profile (
/author/<username>). Many Fediverse platforms redirect to an actor document ifAcceptheader specifies the ActivityPub media type, but not Ghost.One can try to guess the actor ID using the
https://<domain>/.ghost/activitypub/users/<username>template, but this is not reliable. It seems to work only when the username isindex, in other cases an invalid actor document is returned. The username is not checked, by the way, and document is returned even if the user doesn't exist. Here's an example: https://activitypub.ghost.org/.ghost/activitypub/users/wowsuchactor