fix: assume remote users are following each other (#8734)

Misskey does not know if two remote users are following each other.
Because ActivityPub actions would otherwise fail on followers only
notes, we have to assume that two remote users are following each other
when an interaction about a remote note occurs.

packages/backend/src/models/repositories/note.ts

@@ -168,16 +168,22 @@ export const NoteRepository = db.getRepository(Note).extend({
 				return true;
 			} else {
 				// フォロワーかどうか
-				const following = await Followings.findOneBy({
+				const [following, user] = await Promise.all([
-					followeeId: note.userId,
+					Followings.findOneBy({
-					followerId: meId,
+						followeeId: note.userId,
-				});
+						followerId: meId,
+					}),
+					Users.findOneByOrFail({ id: meId }),
+				]);
 
-				if (following == null) {
+				/* If we know the following, everyhting is fine.
-					return false;
+
-				} else {
+				But if we do not know the following, it might be that both the
-					return true;
+				author of the note and the author of the like are remote users,
-				}
+				in which case we can never know the following. Instead we have
+				to assume that the users are following each other.
+				*/
+				return following != null || (note.userHost != null && user.host != null);
 			}
 		}